golub

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Author name code: golub
ADS astronomy entries on 2022-09-14
author:"Golub, Leon"

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Title: Defining the Middle Corona
Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.;
Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski,
Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.;
Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee,
Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs,
Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason,
Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler,
Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina;
Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.;
Vourlidas, Angelos
2022arXiv220804485W Altcode:
The middle corona, the region roughly spanning heliocentric altitudes
from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential
physical transitions and processes that govern the behavior of
coronal outflow into the heliosphere. Eruptions that could disrupt
the near-Earth environment propagate through it. Importantly, it
modulates inflow from above that can drive dynamic changes at lower
heights in the inner corona. Consequently, this region is essential
for comprehensively connecting the corona to the heliosphere and for
developing corresponding global models. Nonetheless, because it is
challenging to observe, the middle corona has been poorly studied by
major solar remote sensing missions and instruments, extending back to
the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent
advances in instrumentation, observational processing techniques,
and a realization of the importance of the region, interest in the
middle corona has increased. Although the region cannot be intrinsically
separated from other regions of the solar atmosphere, there has emerged
a need to define the region in terms of its location and extension
in the solar atmosphere, its composition, the physical transitions
it covers, and the underlying physics believed to be encapsulated by
the region. This paper aims to define the middle corona and give an
overview of the processes that occur there.

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Title: The Airborne Infrared Spectrometer: Development,
Characterization, and the 2017 August 21 Eclipse Observation
Authors: Samra, Jenna E.; Marquez, Vanessa; Cheimets, Peter; DeLuca,
Edward E.; Golub, Leon; Hannigan, James W.; Madsen, Chad A.; Vira,
Alisha; Adams, Arn
2022AJ....164...39S Altcode: 2021arXiv210509419S
On 2017 August 21, the Airborne Infrared Spectrometer (AIR-Spec)
observed the total solar eclipse at an altitude of 14 km from aboard the
NSF/NCAR Gulfstream V research aircraft. The instrument successfully
observed the five coronal emission lines that it was designed to
measure: Si X 1.431 μm, S XI 1.921 μm, Fe IX 2.853 μm, Mg VIII
3.028 μm, and Si IX 3.935 μm. Characterizing these magnetically
sensitive emission lines is an important first step in designing
future instruments to monitor the coronal magnetic field, which
drives space weather events, as well as coronal heating, structure,
and dynamics. The AIR-Spec instrument includes an image stabilization
system, feed telescope, grating spectrometer, and slit-jaw imager. This
paper details the instrument design, optical alignment method, image
processing, and data calibration approach. The eclipse observations
are described and the available data are summarized.

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Title: Parallel Plasma Loops and the Energization of the Solar Corona
Authors: Peter, Hardi; Chitta, Lakshmi Pradeep; Chen, Feng; Pontin,
David I.; Winebarger, Amy R.; Golub, Leon; Savage, Sabrina L.;
Rachmeler, Laurel A.; Kobayashi, Ken; Brooks, David H.; Cirtain,
Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton, Richard J.;
Testa, Paola; Tiwari, Sanjiv K.; Walsh, Robert W.; Warren, Harry P.
2022ApJ...933..153P Altcode: 2022arXiv220515919P
The outer atmosphere of the Sun is composed of plasma heated to
temperatures well in excess of the visible surface. We investigate
short cool and warm (&lt;1 MK) loops seen in the core of an active
region to address the role of field-line braiding in energizing these
structures. We report observations from the High-resolution Coronal
imager (Hi-C) that have been acquired in a coordinated campaign with
the Interface Region Imaging Spectrograph (IRIS). In the core of the
active region, the 172 Å band of Hi-C and the 1400 Å channel of IRIS
show plasma loops at different temperatures that run in parallel. There
is a small but detectable spatial offset of less than 1″ between
the loops seen in the two bands. Most importantly, we do not see
observational signatures that these loops might be twisted around each
other. Considering the scenario of magnetic braiding, our observations
of parallel loops imply that the stresses put into the magnetic field
have to relax while the braiding is applied: the magnetic field never
reaches a highly braided state on these length scales comparable to
the separation of the loops. This supports recent numerical 3D models
of loop braiding in which the effective dissipation is sufficiently
large that it keeps the magnetic field from getting highly twisted
within a loop.

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Title: New Observations of the IR Emission Corona from the 2019 July
2 Eclipse Flight of the Airborne Infrared Spectrometer
Authors: Samra, Jenna E.; Madsen, Chad A.; Cheimets, Peter; DeLuca,
Edward E.; Golub, Leon; Marquez, Vanessa; Reyes, Naylynn Tañón
2022ApJ...933...82S Altcode: 2021arXiv210608760S
The Airborne Infrared Spectrometer (AIR-Spec) was commissioned during
the 2017 total solar eclipse, when it observed five infrared coronal
emission lines from a Gulfstream V research jet owned by the National
Science Foundation and operated by the National Center for Atmospheric
Research. The second AIR-Spec research flight took place during the
2019 July 2 total solar eclipse across the south Pacific. The 2019
eclipse flight resulted in seven minutes of observations, during
which the instrument measured all four of its target emission lines:
S XI 1.393 μm, Si X 1.431 μm, S XI 1.921 μm, and Fe IX 2.853
μm. The 1.393 μm S XI line was detected for the first time, and
probable first detections were made of Si XI 1.934 μm and Fe X 1.947
μm. The 2017 AIR-Spec detection of Fe IX was confirmed and the first
observations were made of the Fe IX line intensity as a function of
solar radius. Telluric absorption features were used to calibrate the
wavelength mapping, instrumental broadening, and throughput of the
instrument. AIR-Spec underwent significant upgrades in preparation for
the 2019 eclipse observation. The thermal background was reduced by a
factor of 30, providing a 5.5× improvement in signal-to-noise ratio,
and the postprocessed pointing stability was improved by a factor of 5
to &lt;10″ rms. In addition, two imaging artifacts were identified
and resolved, improving the spectral resolution and making the 2019
data easier to interpret.

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Title: Real-Time Solar Flare Predictions for Improved Flare
Observations
Authors: Vievering, J. T.; Athiray, P. S.; Buitrago-Casas, J. C.;
Chamberlin, P.; Glesener, L.; Golub, L.; Knoer, V.; Krucker, S.;
Machol, J.; Pantazides, A.; Peck, C.; Reeves, K.; Savage, S.; Schmit,
D.; Smith, B.; Vigil, G.; Winebarger, A.
2022heli.conf.4038V Altcode:
Improving near-term flare forecasts is important for observatories
targeting flare physics that are restricted in FOV and/or observing
time. We propose a tool that aggregates near-real-time signatures of
flare onset to provide early flare predictions.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
Solar Explorer (MUSE). II. Flares and Eruptions
Authors: Cheung, Mark C. M.; Martínez-Sykora, Juan; Testa, Paola;
De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito,
Vanessa; Kerr, Graham S.; Reeves, Katharine K.; Fletcher, Lyndsay; Jin,
Meng; Nóbrega-Siverio, Daniel; Danilovic, Sanja; Antolin, Patrick;
Allred, Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward;
Longcope, Dana; Takasao, Shinsuke; DeRosa, Marc L.; Boerner, Paul;
Jaeggli, Sarah; Nitta, Nariaki V.; Daw, Adrian; Carlsson, Mats; Golub,
Leon; The
2022ApJ...926...53C Altcode: 2021arXiv210615591C
Current state-of-the-art spectrographs cannot resolve the fundamental
spatial (subarcseconds) and temporal (less than a few tens of
seconds) scales of the coronal dynamics of solar flares and eruptive
phenomena. The highest-resolution coronal data to date are based on
imaging, which is blind to many of the processes that drive coronal
energetics and dynamics. As shown by the Interface Region Imaging
Spectrograph for the low solar atmosphere, we need high-resolution
spectroscopic measurements with simultaneous imaging to understand the
dominant processes. In this paper: (1) we introduce the Multi-slit Solar
Explorer (MUSE), a spaceborne observatory to fill this observational
gap by providing high-cadence (&lt;20 s), subarcsecond-resolution
spectroscopic rasters over an active region size of the solar transition
region and corona; (2) using advanced numerical models, we demonstrate
the unique diagnostic capabilities of MUSE for exploring solar coronal
dynamics and for constraining and discriminating models of solar flares
and eruptions; (3) we discuss the key contributions MUSE would make
in addressing the science objectives of the Next Generation Solar
Physics Mission (NGSPM), and how MUSE, the high-throughput Extreme
Ultraviolet Solar Telescope, and the Daniel K Inouye Solar Telescope
(and other ground-based observatories) can operate as a distributed
implementation of the NGSPM. This is a companion paper to De Pontieu
et al., which focuses on investigating coronal heating with MUSE.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
Solar Explorer (MUSE). I. Coronal Heating
Authors: De Pontieu, Bart; Testa, Paola; Martínez-Sykora, Juan;
Antolin, Patrick; Karampelas, Konstantinos; Hansteen, Viggo; Rempel,
Matthias; Cheung, Mark C. M.; Reale, Fabio; Danilovic, Sanja; Pagano,
Paolo; Polito, Vanessa; De Moortel, Ineke; Nóbrega-Siverio, Daniel;
Van Doorsselaere, Tom; Petralia, Antonino; Asgari-Targhi, Mahboubeh;
Boerner, Paul; Carlsson, Mats; Chintzoglou, Georgios; Daw, Adrian;
DeLuca, Edward; Golub, Leon; Matsumoto, Takuma; Ugarte-Urra, Ignacio;
McIntosh, Scott W.; the MUSE Team
2022ApJ...926...52D Altcode: 2021arXiv210615584D
The Multi-slit Solar Explorer (MUSE) is a proposed mission composed of
a multislit extreme ultraviolet (EUV) spectrograph (in three spectral
bands around 171 Å, 284 Å, and 108 Å) and an EUV context imager (in
two passbands around 195 Å and 304 Å). MUSE will provide unprecedented
spectral and imaging diagnostics of the solar corona at high spatial
(≤0.″5) and temporal resolution (down to ~0.5 s for sit-and-stare
observations), thanks to its innovative multislit design. By obtaining
spectra in four bright EUV lines (Fe IX 171 Å, Fe XV 284 Å, Fe XIX-Fe
XXI 108 Å) covering a wide range of transition regions and coronal
temperatures along 37 slits simultaneously, MUSE will, for the first
time, "freeze" (at a cadence as short as 10 s) with a spectroscopic
raster the evolution of the dynamic coronal plasma over a wide range of
scales: from the spatial scales on which energy is released (≤0.″5)
to the large-scale (~170″ × 170″) atmospheric response. We use
numerical modeling to showcase how MUSE will constrain the properties of
the solar atmosphere on spatiotemporal scales (≤0.″5, ≤20 s) and
the large field of view on which state-of-the-art models of the physical
processes that drive coronal heating, flares, and coronal mass ejections
(CMEs) make distinguishing and testable predictions. We describe the
synergy between MUSE, the single-slit, high-resolution Solar-C EUVST
spectrograph, and ground-based observatories (DKIST and others), and
the critical role MUSE plays because of the multiscale nature of the
physical processes involved. In this first paper, we focus on coronal
heating mechanisms. An accompanying paper focuses on flares and CMEs.

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Title: A Strategy for a Coherent and Comprehensive Basis for
Understanding the Middle Corona
Authors: West, M. J.; Seaton, D. B.; Alzate, N.; Caspi, A.; DeForest,
C. E.; Gilly, C. R.; Golub, L.; Higginson, A. K.; Kooi, J. E.; Mason,
J. P.; Rachmeler, L. A.; Reeves, K. K.; Reardon, K.; Rivera, Y. J.;
Savage, S.; Viall, N. M.; Wexler, D. B.
2022heli.conf.4060W Altcode:
We describe a strategy for coherent and comprehensive observations
needed to achieve a fundamental understanding of the middle solar
corona.

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Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Champey, P. R.; Winebarger, A. R.; Kobayashi, K.; Athiray,
P. S.; Hertz, E.; Savage, S.; Beabout, B.; Beabout, D.; Broadway, D.;
Bruccoleri, A. R.; Cheimets, P.; Davis, J.; Duffy, J.; Golub, L.;
Gregory, D. A.; Griffith, C.; Haight, H.; Heilmann, R. K.; Hogue,
B.; Hohl, J.; Hyde, D.; Kegley, J.; Kolodzieczjak, J.; Ramsey, B.;
Ranganathan, J.; Robertson, B.; Schattenburg, M. L.; Speegle, C. O.;
Vigil, G.; Walsh, R.; Weddenorf, B.; Wright, E.
2022JAI....1150010C Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is
a sounding rocket instrument that flew on July 30, 2021 from the
White Sands Missile Range, NM. The instrument was designed to address
specific science questions that require differential emission measures
of the solar soft X-ray spectrum from 6 - 25Å(0.5 - 2.1keV). MaGIXS
comprises a Wolter-I telescope, a slit-jaw imaging system, an identical
pair of grazing incidence paraboloid mirrors, a planar grating and
a CCD camera. While implementing this design, some limitations were
encountered in the production of the X-ray mirrors, which ended up as a
catalyst for the development of a deterministic polishing approach and
an improved meteorological technique that utilizes a computer-generated
hologram (CGH). The opto-mechanical design approach addressed the need
to have adjustable and highly repeatable interfaces to allow for the
complex alignment between the optical sub-assemblies. The alignment
techniques employed when mounting the mirrors and throughout instrument
integration and end-to-end testing are discussed. Also presented are
spatial resolution measurements of the end-to-end point-spread-function
that were obtained during testing in the X-ray Cryogenic Facility
(XRCF) at NASA Marshall Space Flight Center. Lastly, unresolved issues
and off-nominal performance are discussed.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
Solar Explorer (MUSE): II. Flares and Eruptions
Authors: Cheung, Chun Ming Mark; Martinez-Sykora, Juan; Testa, Paola;
De Pontieu, Bart; Chintzoglou, Georgios; Rempel, Matthias; Polito,
Vanessa; Kerr, Graham; Reeves, Katharine; Fletcher, Lyndsay; Jin,
Meng; Nobrega, Daniel; Danilovic, Sanja; Antolin, Patrick; Allred,
Joel; Hansteen, Viggo; Ugarte-Urra, Ignacio; DeLuca, Edward; Longcope,
Dana; Takasao, Shinsuke; DeRosa, Marc; Boerner, Paul; Jaeggli, Sarah;
Nitta, Nariaki; Daw, Adrian; Carlsson, Mats; Golub, Leon
2021AGUFMSH51A..08C Altcode:
Current state-of-the-art spectrographs cannot resolve the fundamental
spatial (sub-arcseconds) and temporal scales (less than a few tens
of seconds) of the coronal dynamics of solar flares and eruptive
phenomena. The highest resolution coronal data to date are based on
imaging, which is blind to many of the processes that drive coronal
energetics and dynamics. As shown by IRIS for the low solar atmosphere,
we need high-resolution spectroscopic measurements with simultaneous
imaging to understand the dominant processes. In this paper: (1)
we introduce the Multi-slit Solar Explorer (MUSE), a spaceborne
observatory to fill this observational gap by providing high-cadence
(&lt;20 s), sub-arcsecond resolution spectroscopic rasters over an
active region size of the solar transition region and corona; (2)
using advanced numerical models, we demonstrate the unique diagnostic
capabilities of MUSE for exploring solar coronal dynamics, and for
constraining and discriminating models of solar flares and eruptions;
(3) we discuss the key contributions MUSE would make in addressing the
science objectives of the Next Generation Solar Physics Mission (NGSPM),
and how MUSE, the high-throughput EUV Solar Telescope (EUVST) and the
Daniel K Inouye Solar Telescope (and other ground-based observatories)
can operate as a distributed implementation of the NGSPM. This is a
companion paper to De Pontieu et al. (2021, also submitted to SH-17),
which focuses on investigating coronal heating with MUSE.

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Title: The Multiview Observatory for Solar Terrestrial Science (MOST)
Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall,
Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe,
Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung,
Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward;
Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy;
DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen,
P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi,
Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal;
DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran;
Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei;
Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan
2021AGUFMSH12A..07G Altcode:
The Multiview Observatory for Solar Terrestrial Science (MOST) is a
comprehensive mission concept targeting the magnetic coupling between
the solar interior and the heliosphere. The wide-ranging imagery and
time series data from MOST will help understand the solar drivers and
the heliospheric responses as a system, discerning and tracking 3D
magnetic field structures, both transient and quiescent in the inner
heliosphere. MOST will have seven remote-sensing and three in-situ
instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate
surface and subsurface magnetism by exploiting the combination of
helioseismic and magnetic-field measurements in the photosphere; (2)
Inner Coronal Imager in EUV (ICIE) to study large-scale structures
such as active regions, coronal holes and eruptive structures by
capturing the magnetic connection between the photosphere and the
corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image
the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to
seamlessly study transient and quiescent large-scale coronal structures
extending from the ICIE field of view (FOV); (5) Faraday Effect
Tracker of Coronal and Heliospheric structures (FETCH), a novel radio
package to determine the magnetic field structure and plasma column
density, and their evolution within 0.5 au; (6) Heliospheric Imager
with Polarization (HIP) to track solar features beyond the WCOR FOV,
study their impact on Earth, and provide important context for FETCH;
(7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams
and shocks propagating into the heliosphere via passive radio emission;
(8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra
of electrons, and ions from H to Fe at multiple spatial locations
and use energetic particles as tracers of magnetic connectivity; (9)
Solar Wind Magnetometer (MAG) to characterize magnetic structures at
1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma
structures at 1 au. MOST will have two large spacecraft with identical
payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4
and behind L5 to carry additional FETCH elements. MOST will build upon
SOHO and STEREO achievements to expand the multiview observational
approach into the first half of the 21st Century.

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Title: Preliminary Results from the Marshall Grazing Incidence X-ray
Spectrometer (MaGIXS)
Authors: Winebarger, Amy; Savage, Sabrina; Kobayashi, Ken; Champey,
Patrick; Golub, Leon; Walsh, Robert; Athiray, P. S.; Bradshaw, Stephen;
Cheimets, Peter; Cirtain, Jonathan; DeLuca, Edward; Del Zanna, Giulio;
Mason, Helen; McKenzie, David; Ramsey, Brian; Reeves, Katharine;
Testa, Paola; Vigil, Genevieve; Warren, Harry
2021AGUFMSH51A..06W Altcode:
Coronal heating mechanisms are notoriously difficult to constrain with
current observations. We present new observations from an instrument
designed to measure a critical diagnostic of the frequency heating
events in active regions. The Marshall Grazing Incidence X-ray
Spectrometer (MaGIXS) is a sounding rocket mission that aims to
observe the soft x-ray solar spectrum (0.6 2.5 nm) with both spatial
and spectral resolution. This wavelength range has several high
temperature and abundance diagnostics that can be used to infer the
coronal heating frequency. MaGIXS will observe the Sun through a 12
x 33 slot, producing “overlappograms, where the spatial and spectral
information are overlapped and must be unfolded. In this presentation,
I will report on the MaGIXS launch and data collection and provide
preliminary analysis of MaGIXS observations.

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Title: Exploring the middle corona: new instrumentation to address
science questions critical to understanding the thermal structure
and dynamic evolution of the middle corona
Authors: DeLuca, Edward; Winebarger, Amy; Reeves, Katharine; Golub,
Leon; Samra, Jenna; Madsen, Chad; Rivera, Yeimy; Karna, Nishu;
Savage, Sabrina; Seaton, Daniel; West, Matthew; Downs, Cooper; Del
Zanna, Giulio
2021AGUFMSH25F2150D Altcode:
The global structure of the largely unexplored middle corona determines
the physical properties of the inner heliosphere, affects the formation
and acceleration of the solar wind, and controls the dynamics of
eruptive events. Tracing the short and long term global evolution
of the extended corona, identifying changes in corona/heliosphere
connectivity and following the dynamic evolution of eruptive events
in this unexplored region will provide observational data that will
clarify how the corona transitions from closed to open, illuminate the
genesis of coronal mass ejections, and provide input for the design
of the next generation of physics based space weather forecasts. This
poster outlines several critical science questions and identifies the
measurements that are required to make substantial progress towards
addressing the questions. We review and discuss the instrumentation
necessary to capture the observations needed for meaningful progress
in this area as well as the role of simulations in the interpretation
of the observations.

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Title: Calibration of the Marshall Grazing Incidence X-Ray
Spectrometer Experiment. II. Flight Instrument Calibration
Authors: Athiray, P. S.; Winebarger, Amy R.; Champey, Patrick;
Kobayashi, Ken; Savage, Sabrina; Beabout, Brent; Beabout, Dyana;
Broadway, David; Bruccoleri, Alexander R.; Cheimets, Peter;
Golub, Leon; Gullikson, Eric; Haight, Harlan; Heilmann, Ralf K.;
Hertz, Edward; Hogue, William; Johnson, Steven; Kegley, Jeffrey;
Kolodziejczak, Jeffery; Madsen, Chad; Schattenburg, Mark L.; Siler,
Richard; Vigil, Genevieve D.; Wright, Ernest
2021ApJ...922...65A Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a
sounding rocket experiment that observes the soft X-ray spectrum of
the Sun from 6.0-24 Å (0.5-2.0 keV), successfully launched on 2021
July 30. End-to-end alignment of the flight instrument and calibration
experiments are carried out using the X-ray and Cryogenic Facility
at NASA Marshall Space Flight Center. In this paper, we present the
calibration experiments of MaGIXS, which include wavelength calibration,
measurement of line spread function, and determination of effective
area. Finally, we use the measured instrument response function to
predict the expected count rates for MaGIXS flight observation looking
at a typical solar active region.

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Title: Calibration of the MaGIXS experiment II: Flight Instrument
Calibration
Authors: Athiray, P. S.; Winebarger, Amy R.; Champey, Patrick;
Kobayashi, Ken; Savage, Sabrina; Beabout, Brent; Beabout, Dyana;
Broadway, David; Bruccoleri, Alexander R.; Cheimets, Peter;
Golub, Leon; Gullikson, Eric; Haight, Harlan; Heilmann, Ralf K.;
Hertz, Edward; Hogue, William; Johnson, Steven; Kegley, Jeffrey;
Kolodziejczak, Jeffery; Madsen, Chad; Schattenburg, Mark L.; Siler,
Richard; Vigil, Genevieve D.; Wright, Ernest
2021arXiv210901720A Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a
sounding rocket experiment that observes the soft X-ray spectrum of
the Sun from 6.0 - 24 Angstrom (0.5 - 2.0 keV), successfully launched
on 30 July 2021. End-to-end alignment of the flight instrument
and calibration experiments are carried out using the X-ray and
Cryogenic Facility (XRCF) at NASA Marshall Space Flight Center. In
this paper, we present the calibration experiments of MaGIXS, which
include wavelength calibration, measurement of line spread function,
and determination of effective area. Finally, we use the measured
instrument response function to predict the expected count rates for
MaGIXS flight observation looking at a typical solar active region

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Title: The First Solar Flare Sounding Rocket Campaign and Its
Potential Impacts for High Energy Solar Instrumentation
Authors: Savage, S.; Winebarger, A.; Glesener, L.; Golub, L.;
Chamberlin, P.; Hi-C Flare Team; Foxsi-4 Team; Snifs Team
2021AAS...23831315S Altcode:
Solar flares are an essential driver of space weather as they account
for the rapid release of powerful amounts of energy (~1032
ergs) in a matter of seconds to hours. Observations from the past
several decades have yielded a wealth of understanding of these events
while at the same time presenting countless new questions. Key gaps
in our knowledge remain that cannot be satisfactorily answered with
available instrumentation, and we are now at the precipice of the value
of incremental improvements in technology versus the need for design
breakthroughs. The latter requires exceptional testing in order to
justify vast investments within Explorer-class mission programs. High
energy instrumentation often invokes the additional requirement of
testing above the absorption layer of the Earth's atmosphere. The NASA
sounding rocket program has been an invaluable pathway for developing
such cutting-edge technologies. However, these suborbital missions
have been severely limited for the development of flare-specific
instrumentation due to the current inability to remain in a holding
pattern until a flare occurs at the White Sands Missile Range (~1 hour)
compounded by the short duration of a flight (~5 minutes of science
observations) in which it is nearly impossible to capture a flare per
chance. In response to this deficiency, a pilot solar flare campaign
has been established to test the ability to launch multiple sounding
rockets (two nearly simultaneously) with instrumentation optimized to
observe flares from the Poker Flat Research Range in Alaska, taking
advantage of the site's ability to accommodate a long holding pattern
(~4 hours per day for several weeks). This capability has been utilized
extensively by the geospace communities. We present an overview of the
first three payloads participating in this pilot program, Hi-C Flare,
FOXSI 4, and SNIFS, and discuss how this new technology development
paradigm could enable the next wave of exploratory flare missions.

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Title: Marshall Grazing Incidence X-ray Spectrometer Slitjaw Imager
Implementation and Performance
Authors: Vigil, Genevieve D.; Winebarger, Amy R.; Kobayashi, Ken;
Cheimets, Peter N.; Champey, Patrick R.; Savage, Sabrina L.; Golub,
Leon; Watkinson, Benjamin; Beabout, Brent; Weddendorf, Bruce; Walsh,
Robert W.
2021SoPh..296...90V Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a slit
spectrograph designed to fly on a sounding-rocket and to observe
the Sun in soft X-rays (SXRs) to determine the frequency of coronal
heating events. The MaGIXS wavelength range (≈ 0.6 - 2.5 nm) has a
significant number of diagnostic lines formed at coronal temperatures,
but developing SXR instrumentation presents several challenges,
including how to efficiently perform context imaging. A slitjaw
image is required for pointing the instrument during flight and for
co-alignment with coordinated data sets after flight, but operating
in the SXR regime implies that a simple normal-incidence optical
system could not be employed to image the same wavelength range as
the spectrograph. Therefore, to avoid the complexity of additional
grazing-incidence optics, the MaGIXS slitjaw system is designed
to image in the extreme ultraviolet (EUV) between roughly 20 - 80
nm. The temperature sensitivity of this EUV bandpass will observe
complementary features visible to the MaGIXS instrument. The image
on the slitjaw is then converted, via a phosphor coating, to readily
detectable visible light. Presented here is the design, implementation,
and characterization of the MaGIXS slitjaw imaging system. The slitjaw
instrument is equipped with an entrance filter that passes EUV light,
along with X-rays, onto the slit, exciting a fluorescent coating and
causing it to emit in the visible. This visible light can then be imaged
by a simple implementation of commercial off-the-shelf (COTS) optics
and low-light camera. Such a design greatly reduces the complexity of
implementing and testing the slitjaw imager for an X-ray instrument
system and will accomplish the pointing and co-alignment requirements
for MaGIXS.

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Title: Physical Characteristics of Unstructured Coronal Clouds
Authors: Asgari-Targhi, M.; Golub, L.; Hahn, M.; Karna, N.; Savin,
D. W.
2021ApJ...910..113A Altcode:
Active regions in the inner solar corona, when observed in X-ray
emission, consist of bright, hot loops surrounded by unstructured
clouds. The emission from the clouds extends to a height of ≍4-5
× 104 km at temperatures of ≍2-3 MK. These "hot clouds"
are variable, but persist for many days and do not appear to connect
directly to the active region streamers or other large-scale structures
observed higher in the corona. We present an observational analysis of
these diffuse structures to establish basic plasma parameters such as
magnetic field strength, particle density, and temperature. The values
of β, the ratio of the plasma pressure to the magnetic field pressure,
were found to be generally less than unity, though often approaching
unity in the upper portions of the active region, where the hot clouds
are located. The magnetic field may therefore only partially confine
these regions and inhibit flare-like instabilities that could otherwise
be driven by gradients of plasma pressure and current density.

---------------------------------------------------------
Title: High resolution soft X-ray spectroscopy and the quest for
the hot (5-10 MK) plasma in solar active regions
Authors: Del Zanna, Giulio; Andretta, Vincenzo; Cargill, Peter J.;
Corso, Alain J.; Daw, Adrian N.; Golub, Leon; Klimchuk, James A.;
Mason, Helen E.
2021FrASS...8...33D Altcode: 2021arXiv210306156D
We discuss the diagnostics available to study the 5--10 MK plasma in
the solar corona, which is key to understanding the heating in the
cores of solar active regions. We present several simulated spectra,
and show that excellent diagnostics are available in the soft X-rays,
around 100 Angstroms, as six ionisation stages of Fe can simultaneously
be observed, and electron densities derived, within a narrow spectral
region. As this spectral range is almost unexplored, we present an
analysis of available and simulated spectra, to compare the hot emission
with the cooler component. We adopt recently designed multilayers to
present estimates of count rates in the hot lines, with a baseline
spectrometer design. Excellent count rates are found, opening up
the exciting opportunity to obtain high-resolution spectroscopy of
hot plasma.

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Title: Imaging Evidence for Solar Wind Outflows Originating from a
Coronal Mass Ejection Footpoint
Authors: Lörinčík, Juraj; Dudík, Jaroslav; Aulanier, Guillaume;
Schmieder, Brigitte; Golub, Leon
2021ApJ...906...62L Altcode: 2020arXiv201004250L
We report on Atmospheric Imaging Assembly observations of plasma
outflows originating in a coronal dimming during a 2015 April 28
filament eruption. After the filament started to erupt, two flare
ribbons formed, one of which had a well-visible hook enclosing a core
(twin) dimming region. Along multiple funnels located in this dimming,
a motion of plasma directed outward started to be visible in the
171 and 193 Å filter channels of the instrument. In time-distance
diagrams, this motion generated a strip-like pattern, which lasted
for more than 5 hr and whose characteristics did not change along
the funnel. We therefore suggest the motion is a signature of
outflows corresponding to velocities ranging between ≍70 and 140
km s-1. Interestingly, the pattern of the outflows and
their velocities were found to be similar to those we observed in a
neighboring ordinary coronal hole. Therefore, the outflows were most
likely a signature of a coronal mass ejection-induced solar wind flowing
along the open-field structures rooted in the dimming region. Further,
the evolution of the hook encircling the dimming region was examined
in the context of the latest predictions imposed for 3D magnetic
reconnection. The observations indicate that the filament's footpoints
were, during their transformation to the dimming region, reconnecting
with surrounding canopies. To our knowledge, our observations present
the first imaging evidence for outflows of plasma from a dimming region.

---------------------------------------------------------
Title: The First Solar Flare Sounding Rocket Campaign and Its
Potential Impacts for High Energy Solar Instrumentation
Authors: Savage, S. L.; Winebarger, A. R.; Glesener, L.; Reeves, K.;
Kobayashi, K.; Golub, L.
2020AGUFMSH056..02S Altcode:
Solar flares are an essential driver of space weather as they account
for the rapid release of powerful amounts of energy (~1032
ergs) in a matter of seconds to hours. Observations from the past
several decades have yielded a wealth of understanding of these events
while at the same time presenting countless new questions. Key gaps
in our knowledge remain that cannot be satisfactorily answered with
available instrumentation, and we are now at the precipice of the
value of incremental improvements in technology versus the need
for design breakthroughs. The latter requires exceptional testing
in order to justify vast investments within Explorer-class mission
programs. High energy instrumentation often invokes the additional
requirement of testing above the absorption layer of the Earth's
atmosphere. The NASA sounding rocket program has been an invaluable
pathway for developing such cutting-edge technologies. However, these
suborbital missions have been severely limited for the development of
flare-specific instrumentation due to the current inability to remain in
a holding pattern until a flare occurs at the White Sands Missile Range
(~1 hour) compounded by the short duration of a flight (~5 minutes of
science observations) in which it is nearly impossible to capture a
flare per chance. In response to this deficiency, a pilot solar flare
campaign has been established to test the ability to launch at least
two sounding rockets with instrumentation optimized to observe flares
from the Poker Flats Research Range in Alaska, taking advantage of the
site's ability to accommodate a long holding pattern (~4 hours per day
for several weeks). This capability has been utilized extensively by the
geospace communities. We will present the first two payloads selected
specifically for this solar pilot program, Hi-C FLARE and FOXSI 4,
and discuss how this new technology development paradigm could enable
the next wave of exploratory flare missions.

---------------------------------------------------------
Title: Updates on the Fundamentals of Impulsive Energy Release in
the Corona Explorer (FIERCE) mission concept
Authors: Shih, A. Y.; Glesener, L.; Krucker, S.; Guidoni, S. E.;
Christe, S.; Reeves, K.; Gburek, S.; Caspi, A.; Alaoui, M.; Allred,
J. C.; Battaglia, M.; Baumgartner, W.; Dennis, B. R.; Drake, J. F.;
Goetz, K.; Golub, L.; Hannah, I. G.; Hayes, L.; Holman, G.; Inglis,
A.; Ireland, J.; Kerr, G. S.; Klimchuk, J. A.; McKenzie, D. E.; Moore,
C. S.; Musset, S.; Reep, J. W.; Ryan, D.; Saint-Hilaire, P.; Savage,
S. L.; Schwartz, R.; Seaton, D. B.; Steslicki, M.; Woods, T. N.
2020AGUFMSH0480012S Altcode:
The Fundamentals of Impulsive Energy Release in the Corona Explorer
( FIERCE ) Medium-Class Explorer (MIDEX) mission concept addresses
the following science questions: What are the physical origins
of space-weather events? How are particles accelerated at the
Sun? How is impulsively released energy transported throughout
the solar atmosphere? How is the solar corona heated? FIERCE
achieves its science objectives through co-optimized X-ray and extreme
ultraviolet (EUV) observations by the following instruments: FOXSI,
a focusing hard X-ray spectroscopic imager that is able to capture the
full range of emission in flares and CMEs (e.g., faint coronal sources
near bright chromospheric sources) THADIS, a high-resolution,
fast-cadence EUV imager that will not saturate for even intense flares
to follow dynamic changes in the configuration of plasma structures
STC, a soft X-ray spectrometer that provides detailed thermal and
elemental composition diagnostics If selected, FIERCE will launch
in 2025, near the peak of the next solar cycle, which is also well timed
with perihelia of Parker Solar Probe and Solar Orbiter . We describe the
status and latest updates of the mission concept since it was proposed
to NASA last year. We also highlight the anticipated science return
from co-observations with other observatories/instruments such as the
Expanded Owens Valley Solar Array (EOVSA) or the STIX instrument on
Solar Orbiter .

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Title: Alignment of the Marshall Grazing Incidence X-ray Spectrometer
(MaGIXS) telescope mirror and spectrometer optics assemblies
Authors: Hertz, Edward; Cheimets, Peter; Hohl, Jacob; Samra, Jenna;
Marquez, Vanessa; Winebarger, Amy; Champey, Patrick; Kobayashi, Ken;
Savage, Sabrina; Golub, Leon; Bruccoleri, Alexander R.; Heilmann,
Ralf K.; Schattenburg, Mark L.; Ramsey, Brian
2020SPIE11444E..8AH Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a
NASA sounding rocket instrument designed and built to observe X-ray
emissions from the Sun's atmosphere in the 6-24Å (0.5-2.0keV) range
while achieving high spectral and spatial resolution along a 8-arcminute
long slit. We describe the alignment process and discuss the results
achieved for assembling the Telescope Mirror Assembly (TMA) and the
Spectrometer Optics Assembly (SOA) prior to final integration into the
MaGIXS instrument. The MaGIXS mirrors are full shell, electroformed
nickel replicated on highly polished mandrels at the Marshall Space
Flight Center (MSFC). The TMA carries a single shell, Wolter Type-1
mirror pair (primary and secondary) formed on a common mandrel. The
SOA includes a matched pair of identical parabolic mirrors and a
planar varied-line spacing (VLS) diffraction grating. We performed the
subassembly alignment and mounting at the Smithsonian Astrophysical
Observatory (SAO) using metrology and precision positioning systems
constructed around the Centroid Detector Assembly (CDA), originally
built for the alignment of the Chandra mirror shells. The MaGIXS
instrument launch has been postponed until 2021 due to the COVID-19
pandemic.

---------------------------------------------------------
Title: The LUCI instrument
Authors: West, M. J.; Kintziger, C.; Haberreiter, M.; Berghmans, D.;
Gissot, S.; Golub, L.; Shestov, S.; Davies, J. A.; Luntama, J. P.
2020AGUFMSH0300007W Altcode:
LUCI (Lagrange eUv Coronal Imager) is a solar imager in the Extreme
UltraViolet (EUV) that is being developed as part of the Lagrange
mission, a mission designed to be positioned at the L5 Lagrangian
point to monitor space weather from its source on the Sun, through the
heliosphere, to the Earth. LUCI will provide solar coronal images at
a 2-3 minute cadence in a pass-band centred on 19.5 nm. Observations
made through this pass-band allow for the detection and monitoring of
semi-static coronal structures such as coronal holes, prominences,
and active regions; as well as transient phenomena such as solar
flares, limb Coronal Mass Ejections (CMEs), EUV waves, and coronal
dimmings. In this presentation I will discuss LUCI's latest
design characteristics and the rationale behind several of the design
decisions. I will present the observational advantages for space-weather
monitoring from the L5 point, especially with an instrument such as
LUCI, which will have a novel off-axis 'wide' field-of-view, designed
to observe the solar disk extending out in to the middle corona, close
to the the Sun-Earth line. I will present proxy data highlighting
structures that can be seen in this region and the current roadmap
for the instrument development.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
solar sounding rocket campaign - Calibration and performance
Authors: Athiray, P. S.; Winebarger, A. R.; Champey, P. R.; Kobayashi,
K.; Savage, S. L.; Vigil, G. D.; Beabout, B.; Beabout, D.; Cheimets,
P.; Hertz, E.; Golub, L.
2020AGUFMSH0480008A Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a
sounding rocket experiment that is designed to observe, for the first
time, soft X-ray spectra of high-temperature, low-emission plasma
of coronal structures spatially resolved along a narrow slit. MaGIXS
observation involves a set of high temperature spectral lines in soft
X-rays from 0.5 - 2.0 keV from an active region core, which will
extend the DEM coverage from 3MK to 10MK constraining the slope of
the DEM fall-off. The novel instrument design includes a Wolter-I
type telescope and a 3-optic grazing-incidence spectrometer. The
spectrometer consists of a finite conjugate mirror pair and a blazed
planar, varied line spaced grating, which disperses the rays on to a
CCD and provides a high spatial and spectral resolution. Component level
instrument testing, integration of the instrument and end-to-end X-ray
calibration are carried out using the X-ray and Cryogenic Facility
(XRCF) at NASA Marshall Space Flight Center. MaGIXS is scheduled
for launch in 2021. We will present the results of X-ray calibration
tests for MaGIXS and discuss the expected inflight performance through
different solar observation scenarios.

---------------------------------------------------------
Title: Space Weather, Extreme Ultraviolet Instruments and the
Multithermal Corona
Authors: Golub, L.; DeLuca, E.; Reeves, K.
2020AGUFMSH0300004G Altcode:
Observation of the solar corona from Earth orbit or from other
locations such as L1 or L5 using suitably-chosen Extreme UltraViolet
(EUV) wavelengths offers the possibility of addressing two major goals
that will improve our ability to forecast and predict geoeffective space
weather events: 1.) improve our understanding of the coronal conditions
that control the opening and closing of the corona to the heliosphere
and consequent solar wind streams, and 2.) improve our understanding
of the physical processes that control the early evolution of CMEs
and the formation of shocks from the solar surface out to beyond the
nominal source surface. The time-varying solar corona is structured
not only in space and in time but also in temperature. A method
for efficiently observing multiple wavelengths, thereby recording
emission lines formed at different temperatures, simultaneously is
therefore desirable. These observations are especially necessary for CME
detection, as the departing magnetized plasma shows markedly different
structures at different temperatures and even the detectability of the
event varies dramatically at different EUV wavelengths. EUV measurements
can help to: i.) determine coronal structuring from its roots out
to beyond 2.5 R_s; ii.) measure the changes in coronal connectivity;
iii.) distinguish between and test solar wind models; iv.) establish
the impact of pre-existing coronal structures on CME evolution;
v.) confront theories of SEP acceleration and preconditioning; and
vi.) establish the extent of energy release behind CMEs.

---------------------------------------------------------
Title: LUCI onboard Lagrange, the next generation of EUV space
weather monitoring
Authors: West, Matthew J.; Kintziger, Christian; Haberreiter, Margit;
Gyo, Manfred; Berghmans, David; Gissot, Samuel; Büchel, Valeria;
Golub, Leon; Shestov, Sergei; Davies, Jackie A.
2020JSWSC..10...49W Altcode: 2020arXiv200904788W
Lagrange eUv Coronal Imager (LUCI) is a solar imager in the Extreme
UltraViolet (EUV) that is being developed as part of the Lagrange
mission, a mission designed to be positioned at the L5 Lagrangian
point to monitor space weather from its source on the Sun, through
the heliosphere, to the Earth. LUCI will use an off-axis two mirror
design equipped with an EUV enhanced active pixel sensor. This type
of detector has advantages that promise to be very beneficial for
monitoring the source of space weather in the EUV. LUCI will also
have a novel off-axis wide field-of-view, designed to observe the
solar disk, the lower corona, and the extended solar atmosphere close
to the Sun-Earth line. LUCI will provide solar coronal images at a
2-3 min cadence in a pass-band centred on 19.5. Observations made
through this pass-band allow for the detection and monitoring of
semi-static coronal structures such as coronal holes, prominences,
and active regions; as well as transient phenomena such as solar
flares, limb coronal mass ejections (CMEs), EUV waves, and coronal
dimmings. The LUCI data will complement EUV solar observations provided
by instruments located along the Sun-Earth line such as PROBA2-SWAP,
SUVI-GOES and SDO-AIA, as well as provide unique observations to improve
space weather forecasts. Together with a suite of other remote-sensing
and in-situ instruments onboard Lagrange, LUCI will provide science
quality operational observations for space weather monitoring.

---------------------------------------------------------
Title: EUV imaging and spectroscopy for improved space weather
forecasting
Authors: Golub, Leon; Cheimets, Peter; DeLuca, Edward E.; Madsen, Chad
A.; Reeves, Katharine K.; Samra, Jenna; Savage, Sabrina; Winebarger,
Amy; Bruccoleri, Alexander R.
2020JSWSC..10...37G Altcode:
Accurate predictions of harmful space weather effects are mandatory
for the protection of astronauts and other assets in space, whether in
Earth or lunar orbit, in transit between solar system objects, or on the
surface of other planetary bodies. Because the corona is multithermal
(i.e., structured not only in space but also in temperature),
wavelength-separated data provide crucial information that is not
available to imaging methods that integrate over temperature. The
extreme ultraviolet (EUV) wavelengths enable us to focus directly on
high temperature coronal plasma associated with solar flares, coronal
mass ejections (CMEs), and shocked material without being overwhelmed by
intensity from the solar disk. Both wide-field imaging and spectroscopic
observations of the solar corona taken from a variety of orbits (e.g.,
Earth, L1, or L5) using suitably-chosen EUV instrumentation offer
the possibility of addressing two major goals to enhance our space
weather prediction capability, namely: (1) Improve our understanding
of the coronal conditions that control the opening and closing of the
corona to the heliosphere and consequent solar wind streams, and (2)
Improve our understanding of the physical processes that control the
early evolution of CMEs and the formation of shocks, from the solar
surface out into the extended corona.

---------------------------------------------------------
Title: Observation and Modeling of High-temperature Solar Active
Region Emission during the High-resolution Coronal Imager Flight of
2018 May 29
Authors: Warren, Harry P.; Reep, Jeffrey W.; Crump, Nicholas A.;
Ugarte-Urra, Ignacio; Brooks, David H.; Winebarger, Amy R.; Savage,
Sabrina; De Pontieu, Bart; Peter, Hardi; Cirtain, Jonathan W.; Golub,
Leon; Kobayashi, Ken; McKenzie, David; Morton, Richard; Rachmeler,
Laurel; Testa, Paola; Tiwari, Sanjiv; Walsh, Robert
2020ApJ...896...51W Altcode:
Excellent coordinated observations of NOAA active region 12712 were
obtained during the flight of the High-resolution Coronal Imager (Hi-C)
sounding rocket on 2018 May 29. This region displayed a typical active
region core structure with relatively short, high-temperature loops
crossing the polarity inversion line and bright "moss" located at the
footpoints of these loops. The differential emission measure (DEM) in
the active region core is very sharply peaked at about 4 MK. Further,
there is little evidence for impulsive heating events in the moss, even
at the high spatial resolution and cadence of Hi-C. This suggests that
active region core heating is occurring at a high frequency and keeping
the loops close to equilibrium. To create a time-dependent simulation of
the active region core, we combine nonlinear force-free extrapolations
of the measured magnetic field with a heating rate that is dependent
on the field strength and loop length and has a Poisson waiting time
distribution. We use the approximate solutions to the hydrodynamic
loop equations to simulate the full ensemble of active region core
loops for a range of heating parameters. In all cases, we find that
high-frequency heating provides the best match to the observed DEM. For
selected field lines, we solve the full hydrodynamic loop equations,
including radiative transfer in the chromosphere, to simulate transition
region and chromospheric emission. We find that for heating scenarios
consistent with the DEM, classical signatures of energy release,
such as transition region brightenings and chromospheric evaporation,
are weak, suggesting that they would be difficult to detect.

---------------------------------------------------------
Title: A New Facility for Airborne Solar Astronomy: NASA's WB-57 at
the 2017 Total Solar Eclipse
Authors: Caspi, Amir; Seaton, Daniel B.; Tsang, Constantine C. C.;
DeForest, Craig E.; Bryans, Paul; DeLuca, Edward E.; Tomczyk,
Steven; Burkepile, Joan T.; Casey, Thomas "Tony"; Collier, John;
Darrow, Donald "DD"; Del Rosso, Dominic; Durda, Daniel D.; Gallagher,
Peter T.; Golub, Leon; Jacyna, Matthew; Johnson, David "DJ"; Judge,
Philip G.; Klemm, Cary "Diddle"; Laurent, Glenn T.; Lewis, Johanna;
Mallini, Charles J.; Parent, Thomas "Duster"; Propp, Timothy; Steffl,
Andrew J.; Warner, Jeff; West, Matthew J.; Wiseman, John; Yates,
Mallory; Zhukov, Andrei N.; NASA WB-57 2017 Eclipse Observing Team
2020ApJ...895..131C Altcode: 2020arXiv200409658C
NASA's WB-57 High Altitude Research Program provides a deployable,
mobile, and stratospheric platform for scientific research. Airborne
platforms are of particular value for making coronal observations
during total solar eclipses because of their ability both to follow the
Moon's shadow and to get above most of the atmospheric air mass that
can interfere with astronomical observations. We used the 2017 August
21 eclipse as a pathfinding mission for high-altitude airborne solar
astronomy, using the existing high-speed visible-light and near/midwave
infrared imaging suite mounted in the WB-57 nose cone. In this paper,
we describe the aircraft, the instrument, and the 2017 mission;
operations and data acquisition; and preliminary analysis of data
quality from the existing instrument suite. We describe benefits and
technical limitations of this platform for solar and other astronomical
observations. We present a preliminary analysis of the visible-light
data quality and discuss the limiting factors that must be overcome
with future instrumentation. We conclude with a discussion of lessons
learned from this pathfinding mission and prospects for future research
at upcoming eclipses, as well as an evaluation of the capabilities of
the WB-57 platform for future solar astronomy and general astronomical
observation.

---------------------------------------------------------
Title: The Drivers of Active Region Outflows into the Slow Solar Wind
Authors: Brooks, David H.; Winebarger, Amy R.; Savage, Sabrina; Warren,
Harry P.; De Pontieu, Bart; Peter, Hardi; Cirtain, Jonathan W.; Golub,
Leon; Kobayashi, Ken; McIntosh, Scott W.; McKenzie, David; Morton,
Richard; Rachmeler, Laurel; Testa, Paola; Tiwari, Sanjiv; Walsh, Robert
2020ApJ...894..144B Altcode: 2020arXiv200407461B
Plasma outflows from the edges of active regions have been suggested as
a possible source of the slow solar wind. Spectroscopic measurements
show that these outflows have an enhanced elemental composition,
which is a distinct signature of the slow wind. Current spectroscopic
observations, however, do not have sufficient spatial resolution to
distinguish what structures are being measured or determine the driver
of the outflows. The High-resolution Coronal Imager (Hi-C) flew on a
sounding rocket in 2018 May and observed areas of active region outflow
at the highest spatial resolution ever achieved (250 km). Here we use
the Hi-C data to disentangle the outflow composition signatures observed
with the Hinode satellite during the flight. We show that there are
two components to the outflow emission: a substantial contribution
from expanded plasma that appears to have been expelled from closed
loops in the active region core and a second contribution from dynamic
activity in active region plage, with a composition signature that
reflects solar photospheric abundances. The two competing drivers of the
outflows may explain the variable composition of the slow solar wind.

---------------------------------------------------------
Title: Improving Space Weather Forecasting with EUV Observations
Authors: Golub, L.
2020LPICo2241.5023G Altcode:
Accurate predictions of harmful space weather effects are mandatory for
the protection of astronauts at the Moon. Observation of the corona
at EUV wavelengths offers the possibility of improving our forecasts
of geo- and seleno-effective events.

---------------------------------------------------------
Title: Is the High-Resolution Coronal Imager Resolving Coronal
Strands? Results from AR 12712
Authors: Williams, Thomas; Walsh, Robert W.; Winebarger, Amy R.;
Brooks, David H.; Cirtain, Jonathan W.; De Pontieu, Bart; Golub,
Leon; Kobayashi, Ken; McKenzie, David E.; Morton, Richard J.; Peter,
Hardi; Rachmeler, Laurel A.; Savage, Sabrina L.; Testa, Paola; Tiwari,
Sanjiv K.; Warren, Harry P.; Watkinson, Benjamin J.
2020ApJ...892..134W Altcode: 2020arXiv200111254W
Following the success of the first mission, the High-Resolution
Coronal Imager (Hi-C) was launched for a third time (Hi-C 2.1)
on 2018 May 29 from the White Sands Missile Range, NM, USA. On this
occasion, 329 s of 17.2 nm data of target active region AR 12712 were
captured with a cadence of ≈4 s, and a plate scale of 0.129 arcsec
pixel-1. Using data captured by Hi-C 2.1 and co-aligned
observations from SDO/AIA 17.1 nm, we investigate the widths of 49
coronal strands. We search for evidence of substructure within the
strands that is not detected by AIA, and further consider whether these
strands are fully resolved by Hi-C 2.1. With the aid of multi-scale
Gaussian normalization, strands from a region of low emission that can
only be visualized against the contrast of the darker, underlying moss
are studied. A comparison is made between these low-emission strands
and those from regions of higher emission within the target active
region. It is found that Hi-C 2.1 can resolve individual strands as
small as ≈202 km, though the more typical strand widths seen are
≈513 km. For coronal strands within the region of low emission, the
most likely width is significantly narrower than the high-emission
strands at ≈388 km. This places the low-emission coronal strands
beneath the resolving capabilities of SDO/AIA, highlighting the need
for a permanent solar observatory with the resolving power of Hi-C.

---------------------------------------------------------
Title: Total solar eclipse 2017 in USA: deep coronal spectra
Authors: Koutchmy, S.; Baudin, F.; Abdi, Sh.; Golub, L.; Sèvre, F.
2019sf2a.conf..363K Altcode:
Total eclipses permit a deep analysis of both the inner and the
outer parts of the solar corona using the Thomson scattered (inverse
Compton effect on free electrons at millions degrees T^{\circ} )
continuum White- Light (W-L) radiations and the spectrum of forbidden
emission lines from hot highly ionized ions of iron, nickel, argon,
etc. Spectra are largely affected by the superposition of the solar
light scattered and diffracted by the interplanetary dust particles
orbiting the Sun at large distances but intercepted along the line
of sight (los)\citep{1973ApJ...186..671K}. Sometimes the parasitic
light due to multiple scattering from the ground and from the Earth
atmosphere should be removed using the light observed on the Moon image
background. After sufficiently dispersing the W-L corona, the Fraunhofer
(F) spectrum of the dust corona appears with its absorption (dark)
lines of known equivalent widths and the continuum Thomson radiation
can be extracted. The identified emission (bright) lines of ions with
different degrees of ionization are studied to permit an evaluation
of i/ relative abundances (compared to photospheric abundances), ii/
temperatures, iii/ non-thermal velocities and the resulting from the
analysis of the departures from a Gaussian profile of net Doppler shifts
after integration along the los. 60 spectra were obtained during the
totality using a specially designed slit spectroscopic experiment for
providing an accurate analysis of the most typical "broadly averaged"
parts of the quasi-minimum of activity type corona. With the scanning
+/- 3 solar radii long slit a .072 nm FWHM effective resolution
was obtained in the range of 510 to 590 nm. The background sky was
exceptionally clear during this US total eclipse of Aug. 21, 2017
as observed from our site in Idaho; spectra are without significant
parasitic light on the Moon disk. The K+F continuum corona is well
exposed up to at least 1 solar radius (Rs) from the limb and further
out with a lower S/N ratio, showing several forbidden coronal emission
lines. The F-corona can be measured even at the solar limb where its
intensity reached near 6\% of the K-corona intensity. Streamers, active
region enhancements and polar coronal holes (CHs) are well measured on
each 1 sec exposure time coronal spectra see Fig. \ref{author1:fig1};
the 2^{nd} contact showing the chromospheric and the most inner layers
emission lines was observed with a fast sequence and exposure time 10
times shorter. New weak emission lines were also discovered and/or
confirmed see Fig. \ref{author1:fig2} ; their identifications are
proposed. The rarely observed high FIP ArX \citep{2018ApJ...852...52D}
line is recorded almost everywhere and a new nearby FeX line is
well identified; the classical low FIP FeXIV and NiXIII lines are
well recorded everywhere without over-exposure. For the 1st time hot
lines are also measured at low levels inside the CH regions, at both
poles. The radial variations of the corrected non-thermal turbulent
velocities of the lines do not show a great departure from the average
values. No significantly large Doppler shifts are seen nowhere in
the inner and the middle corona although the whole corona is almost
covered.\citep{Koutchmy} The corona is confirmed to be made of a mixing
of hot and less hot components everywhere around the Sun, due to the
yet unidentified magnetic origin heating processes reflected in our
spectra and in the line profiles. Coronal density variations are well
reflected by the K-corona continuum intensity variations the azimuthal
and radial direction variations will permit the interpretation of the
emission measures to be compared with the simultaneously obtained AIA
images from the SDO space mission. The W-L images taken simultaneously
shows a much better spatial resolution with images of bright background
well known stars that permit to deduce an excellent absolute calibration
needed to deduce the electron densities and to check our F-corona model,
see \ref{author1:fig3}.

---------------------------------------------------------
Title: Improving Space Weather Forecasting With Wide-Field EUV
Observations
Authors: Golub, L.; Savage, S. L.
2019AGUFMSH13A..05G Altcode:
Observation of the solar corona from earth orbit or from other
locations such as L1 or L5 using suitably-chosen EUV wavelengths
offers the possibility of addressing two major goals that will
improve our ability to forecast and predict geoeffective space weather
events: 1.) improve our understanding of the coronal conditions that
control the opening and closing of the corona to the heliosphere,
and 2.) improve our understanding of the physical processes that
control the evolution of CMEs and the formation of shocks from the
solar surface out to beyond the nominal source surface. Forecasting
models such as EUHFORIA find that predictions at 1 au are extremely
sensitive to the initial conditions input to the model, and EUV
imaging plus spectroscopic imaging data, such as that proposed by the
COSIE investigation, can determine 8 of the 10 parameters used. This
combination of EUV measurements can help to: i.) determine coronal
structuring from its roots out to beyond 2.5 R_s; ii.) measure the
changes in coronal connectivity; iii.) distinguish between and test
solar wind models; iv.) establish the impact of pre-existing coronal
structures on CME evolution; v.) confront theories of SEP acceleration
and preconditioning; and vi.) establish the extent of energy release
behind CMEs.

---------------------------------------------------------
Title: Hi-C 2.1 Observations of Jetlet-like Events at Edges of Solar
Magnetic Network Lanes
Authors: Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.;
Winebarger, Amy R.; Tiwari, Sanjiv K.; Savage, Sabrina L.; Golub, Leon
E.; Rachmeler, Laurel A.; Kobayashi, Ken; Brooks, David H.; Cirtain,
Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton, Richard J.;
Peter, Hardi; Testa, Paola; Walsh, Robert W.; Warren, Harry P.
2019ApJ...887L...8P Altcode: 2019arXiv191102331P
We present high-resolution, high-cadence observations of six,
fine-scale, on-disk jet-like events observed by the High-resolution
Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We
combine the Hi-C 2.1 images with images from the Solar Dynamics
Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and the Interface
Region Imaging Spectrograph (IRIS), and investigate each event’s
magnetic setting with co-aligned line-of-sight magnetograms from the
SDO/Helioseismic and Magnetic Imager (HMI). We find that (i) all six
events are jetlet-like (having apparent properties of jetlets), (ii)
all six are rooted at edges of magnetic network lanes, (iii) four of
the jetlet-like events stem from sites of flux cancelation between
majority-polarity network flux and merging minority-polarity flux, and
(iv) four of the jetlet-like events show brightenings at their bases
reminiscent of the base brightenings in coronal jets. The average
spire length of the six jetlet-like events (9000 ± 3000 km) is three
times shorter than that for IRIS jetlets (27,000 ± 8000 km). While
not ruling out other generation mechanisms, the observations suggest
that at least four of these events may be miniature versions of both
larger-scale coronal jets that are driven by minifilament eruptions
and still-larger-scale solar eruptions that are driven by filament
eruptions. Therefore, we propose that our Hi-C events are driven by
the eruption of a tiny sheared-field flux rope, and that the flux rope
field is built and triggered to erupt by flux cancelation.

---------------------------------------------------------
Title: Young Solar Wind in the Grip of the Sun's Corona
Authors: Kasper, J. C.; Bale, S. D.; Belcher, J. W.; Berthomier, M.;
Case, A. W.; Chandran, B. D. G.; Curtis, D. W.; Gallagher, D. L.;
Gary, S. P.; Golub, L.; Halekas, J. S.; Ho, G. C.; Horbury, T. S.;
Hu, Q.; Huang, J.; Klein, K. G.; Korreck, K. E.; Larson, D. E.; Livi,
R.; Maruca, B.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Martinović,
M.; McGinnis, D.; Pogorelov, N. V.; Richardson, J. D.; Skoug, R. M.;
Steinberg, J. T.; Stevens, M. L.; Szabo, A.; Velli, M.; Whittlesey,
P. L.; Wright, K. H., Jr.; Zank, G. P.; MacDowall, R. J.; McComas,
D. J.; McNutt, R. L., Jr.; Pulupa, M.; Raouafi, N. E.; Schwadron, N.
2019AGUFMSH11A..02K Altcode:
The birthplace of the solar wind is the corona of our Sun, where
unidentified mechanisms heat the plasma to millions of Kelvin and
magnetic fields shape the flow of particles and waves. The plasma is
unstable, accelerating as it expands away from the Sun, exceeding
the speed of sound at a heliocentric distance of a few solar radii
(Rs) and the Alfvén speed at 36 Rs, beyond which the wind decouples
from the corona. Here, we show the first observations of the young,
low-Alfvén-mach-number wind obtained by the Solar Wind Electrons Alphas
and Protons (SWEAP) plasma instruments on Parker Solar Probe (PSP)
during its first two encounters with the Sun. Once PSP dropped below a
quarter of the distance from the Sun to the Earth, SWEAP began to detect
(for the first time) a persistent and growing rotational circulation
of the plasma around the Sun peaking at 40-50 km/s at perihelion as the
Alfvén mach number fell to 1.5. This finding may support theories for
enhanced stellar angular momentum loss due to rigid coronal rotation,
but the circulation is large, and angular momentum does not appear
to be conserved, suggesting that torques still act on the young wind
at these distances. PSP also measured numerous intense and organized
Alfvénic velocity spikes with strong propagating field reversals
and large jumps in speed. These field reversals and jets call for an
overhaul in our understanding of the turbulent fluctuations that may,
by energizing the solar wind, hold the key to its origin.

---------------------------------------------------------
Title: Combined Next-Generation X-ray and EUV Observations with the
FIERCE Mission Concept
Authors: Shih, A. Y.; Glesener, L.; Christe, S.; Reeves, K.; Gburek,
S.; Alaoui, M.; Allred, J. C.; Baumgartner, W.; Caspi, A.; Dennis,
B. R.; Drake, J. F.; Goetz, K.; Golub, L.; Guidoni, S. E.; Inglis,
A.; Hannah, I. G.; Holman, G.; Hayes, L.; Ireland, J.; Kerr, G. S.;
Klimchuk, J. A.; Krucker, S.; McKenzie, D. E.; Moore, C. S.; Musset,
S.; Reep, J. W.; Ryan, D.; Saint-Hilaire, P.; Savage, S. L.; Seaton,
D. B.; Steslicki, M.; Woods, T. N.
2019AGUFMSH33A..08S Altcode:
While there have been significant advances in our understanding
of impulsive energy release at the Sun through the combination
of RHESSI X-ray observations and SDO/AIA EUV observations, there
is a clear science need for significantly improved X-ray and EUV
observations. These new observations must capture the full range
of emission in flares and CMEs (e.g., faint coronal sources near
bright chromospheric sources), connect the intricate evolution of
energy release with dynamic changes in the configuration of plasma
structures, and identify the signatures of impulsive energy release in
even the quiescent Sun. The Fundamentals of Impulsive Energy Release
in the Corona Explorer ( FIERCE ) MIDEX mission concept makes these
observations by combining the two instruments previously proposed on the
FOXSI SMEX mission concept - a focusing hard X-ray spectroscopic imager
and a soft X-ray spectrometer - with a high-resolution EUV imager that
will not saturate for even intense flares. All instruments observe at
high cadence to capture the initiation of solar transient events and
the fine time structure within events. FIERCE would launch in mid-2025,
near the peak of the next solar cycle, which is also well timed with
perihelions of Parker Solar Probe and Solar Orbiter.

---------------------------------------------------------
Title: Alfvénic velocity spikes and rotational flows in the near-Sun
solar wind
Authors: Kasper, J. C.; Bale, S. D.; Belcher, J. W.; Berthomier,
M.; Case, A. W.; Chandran, B. D. G.; Curtis, D. W.; Gallagher, D.;
Gary, S. P.; Golub, L.; Halekas, J. S.; Ho, G. C.; Horbury, T. S.;
Hu, Q.; Huang, J.; Klein, K. G.; Korreck, K. E.; Larson, D. E.; Livi,
R.; Maruca, B.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Martinovic,
M.; McGinnis, D.; Pogorelov, N. V.; Richardson, J. D.; Skoug, R. M.;
Steinberg, J. T.; Stevens, M. L.; Szabo, A.; Velli, M.; Whittlesey,
P. L.; Wright, K. H.; Zank, G. P.; MacDowall, R. J.; McComas, D. J.;
McNutt, R. L.; Pulupa, M.; Raouafi, N. E.; Schwadron, N. A.
2019Natur.576..228K Altcode:
The prediction of a supersonic solar wind1 was first
confirmed by spacecraft near Earth2,3 and later
by spacecraft at heliocentric distances as small as 62 solar
radii4. These missions showed that plasma accelerates
as it emerges from the corona, aided by unidentified processes that
transport energy outwards from the Sun before depositing it in the
wind. Alfvénic fluctuations are a promising candidate for such a
process because they are seen in the corona and solar wind and contain
considerable energy5-7. Magnetic tension forces the corona
to co-rotate with the Sun, but any residual rotation far from the Sun
reported until now has been much smaller than the amplitude of waves
and deflections from interacting wind streams8. Here we
report observations of solar-wind plasma at heliocentric distances
of about 35 solar radii9-11, well within the distance
at which stream interactions become important. We find that Alfvén
waves organize into structured velocity spikes with duration of up to
minutes, which are associated with propagating S-like bends in the
magnetic-field lines. We detect an increasing rotational component
to the flow velocity of the solar wind around the Sun, peaking at
35 to 50 kilometres per second—considerably above the amplitude of
the waves. These flows exceed classical velocity predictions of a few
kilometres per second, challenging models of circulation in the corona
and calling into question our understanding of how stars lose angular
momentum and spin down as they age12-14.

---------------------------------------------------------
Title: Coronal Solar Magnetism Observatory Science Objectives
Authors: Gibson, S. E.; Tomczyk, S.; Burkepile, J.; Casini, R.;
DeLuca, E.; de Toma, G.; de Wijn, A.; Fan, Y.; Golub, L.; Judge,
P. G.; Landi, E.; McIntosh, S. W.; Reeves, K.; Seaton, D. B.; Zhang, J.
2019AGUFMSH11C3395G Altcode:
Space-weather forecast capability is held back by our current
lack of basic scientific understanding of CME magnetic evolution,
and the coronal magnetism that structures and drives the solar
wind. Comprehensive observations of the global magnetothermal
environment of the solar atmosphere are needed for progress. When fully
implemented, the COSMO suite of synoptic ground-based telescopes will
provide the community with comprehensive and simultaneous measurements
of magnetism, temperature, density and plasma flows and waves from the
photosphere through the chromosphere and out into the corona. We will
discuss how these observations will uniquely address a set of science
objectives that are central to the field of solar and space physics:
in particular, to understand the storage and release of magnetic energy,
to understand CME dynamics and consequences for shocks, to determine the
role of waves in solar atmospheric heating and solar wind acceleration,
to understand how the coronal magnetic field relates to the solar
dynamo, and to constrain and improve space-weather forecast models.

---------------------------------------------------------
Title: Fine-scale Explosive Energy Release at Sites of Prospective
Magnetic Flux Cancellation in the Core of the Solar Active Region
Observed by Hi-C 2.1, IRIS, and SDO
Authors: Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.;
De Pontieu, Bart; Winebarger, Amy R.; Golub, Leon; Savage, Sabrina L.;
Rachmeler, Laurel A.; Kobayashi, Ken; Testa, Paola; Warren, Harry P.;
Brooks, David H.; Cirtain, Jonathan W.; McKenzie, David E.; Morton,
Richard J.; Peter, Hardi; Walsh, Robert W.
2019ApJ...887...56T Altcode: 2019arXiv191101424T
The second Hi-C flight (Hi-C 2.1) provided unprecedentedly high spatial
and temporal resolution (∼250 km, 4.4 s) coronal EUV images of Fe IX/X
emission at 172 Å of AR 12712 on 2018 May 29, during 18:56:21-19:01:56
UT. Three morphologically different types (I: dot-like; II: loop-like;
III: surge/jet-like) of fine-scale sudden-brightening events (tiny
microflares) are seen within and at the ends of an arch filament system
in the core of the AR. Although type Is (not reported before) resemble
IRIS bombs (in size, and brightness with respect to surroundings),
our dot-like events are apparently much hotter and shorter in span
(70 s). We complement the 5 minute duration Hi-C 2.1 data with SDO/HMI
magnetograms, SDO/AIA EUV images, and IRIS UV spectra and slit-jaw
images to examine, at the sites of these events, brightenings and
flows in the transition region and corona and evolution of magnetic
flux in the photosphere. Most, if not all, of the events are seated
at sites of opposite-polarity magnetic flux convergence (sometimes
driven by adjacent flux emergence), implying likely flux cancellation
at the microflare’s polarity inversion line. In the IRIS spectra
and images, we find confirming evidence of field-aligned outflow from
brightenings at the ends of loops of the arch filament system. In types
I and II the explosion is confined, while in type III the explosion
is ejective and drives jet-like outflow. The light curves from Hi-C,
AIA, and IRIS peak nearly simultaneously for many of these events,
and none of the events display a systematic cooling sequence as seen in
typical coronal flares, suggesting that these tiny brightening events
have chromospheric/transition region origin.

---------------------------------------------------------
Title: The High-Resolution Coronal Imager, Flight 2.1
Authors: Rachmeler, Laurel A.; Winebarger, Amy R.; Savage, Sabrina L.;
Golub, Leon; Kobayashi, Ken; Vigil, Genevieve D.; Brooks, David H.;
Cirtain, Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton,
Richard J.; Peter, Hardi; Testa, Paola; Tiwari, Sanjiv K.; Walsh,
Robert W.; Warren, Harry P.; Alexander, Caroline; Ansell, Darren;
Beabout, Brent L.; Beabout, Dyana L.; Bethge, Christian W.; Champey,
Patrick R.; Cheimets, Peter N.; Cooper, Mark A.; Creel, Helen K.;
Gates, Richard; Gomez, Carlos; Guillory, Anthony; Haight, Harlan;
Hogue, William D.; Holloway, Todd; Hyde, David W.; Kenyon, Richard;
Marshall, Joseph N.; McCracken, Jeff E.; McCracken, Kenneth; Mitchell,
Karen O.; Ordway, Mark; Owen, Tim; Ranganathan, Jagan; Robertson,
Bryan A.; Payne, M. Janie; Podgorski, William; Pryor, Jonathan; Samra,
Jenna; Sloan, Mark D.; Soohoo, Howard A.; Steele, D. Brandon; Thompson,
Furman V.; Thornton, Gary S.; Watkinson, Benjamin; Windt, David
2019SoPh..294..174R Altcode: 2019arXiv190905942R
The third flight of the High-Resolution Coronal Imager (Hi-C 2.1)
occurred on May 29, 2018; the Sounding Rocket was launched from White
Sands Missile Range in New Mexico. The instrument has been modified
from its original configuration (Hi-C 1) to observe the solar corona
in a passband that peaks near 172 Å, and uses a new, custom-built
low-noise camera. The instrument targeted Active Region 12712, and
captured 78 images at a cadence of 4.4 s (18:56:22 - 19:01:57 UT; 5
min and 35 s observing time). The image spatial resolution varies due
to quasi-periodic motion blur from the rocket; sharp images contain
resolved features of at least 0.47 arcsec. There are coordinated
observations from multiple ground- and space-based telescopes providing
an unprecedented opportunity to observe the mass and energy coupling
between the chromosphere and the corona. Details of the instrument
and the data set are presented in this paper.

---------------------------------------------------------
Title: New deep coronal spectra from the 2017 total solar eclipse
Authors: Koutchmy, S.; Baudin, F.; Abdi, Sh.; Golub, L.; Sèvre, F.
2019A&A...632A..86K Altcode: 2019arXiv191001372K
Context. The origin of the high temperature of the solar corona, in
both the inner bright parts and the more outer parts showing flows
toward the solar wind, is not understood well yet. Total eclipses
permit a deep analysis of both the inner and the outer parts of the
corona using the continuum white-light (W-L) radiations from electrons
(K-corona), the superposed spectrum of forbidden emission lines from
ions (E-corona), and the dust component with F-lines (F-corona). 
Aims: By sufficiently dispersing the W-L spectrum, the Fraunhofer (F)
spectrum of the dust component of the corona appears and the continuum
Thomson radiation can be evaluated. The superposed emission lines
of ions with different degrees of ionization are studied to allow the
measurement of temperatures, non-thermal velocities, Doppler shifts, and
abundances to constrain the proposed heating mechanisms and understand
the origin of flows that lead to solar wind. Methods: We describe
a slit spectroscopic experiment of high spectral resolution to provide
an analysis of the most typical parts of the quasi-minimum type corona
observed during the total solar eclipse of Aug. 21, 2017 from Idaho,
USA. Streamers, active region enhancements, and polar coronal holes
(CHs) are measured well using deep spectra. Results: Sixty
spectra are obtained during the totality with a long slit, covering ±3
solar radii in the range of 510 nm to 590 nm. The K+F continuum corona
is exposed well up to two solar radii. The F-corona can be measured
even at the solar limb. New weak emission lines were discovered or
confirmed. The rarely observed Ar X line is detected almost everywhere;
the Fe XIV and Ni XIII lines are clearly detected everywhere. For
the first time hot lines are also measured inside the CH regions. The
radial variations of the non-thermal turbulent velocities of the lines
do not show a great departure from the average values. No significantly
large Doppler shifts are seen anywhere in the inner or the middle
corona. The wings of the Fe XIV line show some non-Gaussianity. Conclusions: Deep slit coronal spectra offered an opportunity for
diagnosing several aspects of coronal physics during a well observed
total eclipse without extended investments. The analysis of the ionic
emission line profiles offers several powerful diagnostics of the
coronal dynamics; the precise measurement of the F-continuum component
provides insight into the ubiquitous dust corona at the solar limb.

---------------------------------------------------------
Title: FIERCE Science: Expected Results From a High-Energy
Medium-Class Explorer
Authors: Glesener, L.; Shih, A. Y.; Christe, S.; Reeves, K.; Gburek,
S.; Alaoui, M.; Allred, J. C.; Baumgartner, W.; Caspi, A.; Dennis,
B. R.; Drake, J. F.; Golub, L.; Goetz, K.; Guidoni, S. E.; Hannah,
I. G.; Hayes, L.; Holman, G.; Inglis, A.; Ireland, J.; Kerr, G. S.;
Klimchuk, J. A.; Krucker, S.; McKenzie, D. E.; Moore, C. S.; Musset,
S.; Reep, J. W.; Ryan, D.; Saint-Hilaire, P.; Savage, S. L.; Seaton,
D. B.; Steslicki, M.; Woods, T. N.
2019AGUFMSH31C3313G Altcode:
A variety of individual X-ray and EUV instruments have probed
high-energy aspects of the Sun over the decades, each contributing
pieces to the puzzles of the energization, heating, and acceleration of
solar plasma and particles. But fundamental difficulties in sensitivity
and dynamic range impart big challenges in probing the details of
particle acceleration sites, understanding how eruptions and flares are
initiated, and tracking the intricacies of energy transfer as flares
evolve. The Fundamentals of Impulsive Energy Release in the Corona
Explorer ( FIERCE ) mission will make substantial leaps forward in
these scientific ventures by combining a variety of instruments into
one platform, each optimized to have high sensitivity and dynamic
range. FIERCE is a proposed NASA Heliophysics Medium-Class Explorer
that will investigate high-energy solar phenomena across a variety
of spectral and spatial dimensions. It combines hard X-ray imaging
spectroscopy (via focusing, for the first time for a solar-dedicated
spacecraft), spatially integrated soft X-ray spectroscopy, and fast,
high-resolution extreme ultraviolet imaging at coronal and flare
temperatures. FIERCE uses this array of instruments to make important
contributions toward probing the genesis of space weather events,
the acceleration of particles, the transport of flare energy, and the
heating of the corona. Here, we present some of the expected science
outcomes for the FIERCE observatory, concentrating on the ways in which
FIERCE can probe confined and eruptive events, particle acceleration
everywhere it may occur on the Sun, and the connections of solar
high-energy phenomena to the heliosphere.

---------------------------------------------------------
Title: High-Altitude Instrumentation for Infrared Observations of
the Solar Corona
Authors: Samra, J.; Cheimets, P.; DeLuca, E.; Golub, L.; Hannigan,
J. W.; Judge, P. G.; Madsen, C. A.; Marquez, V.; Tañón Reyes, N.;
Tomczyk, S.
2019AGUFMSH43B..07S Altcode:
High-altitude infrared remote sensing is a promising new method for
measuring coronal plasma and magnetic fields. We present new results
from a recent airborne eclipse mission and outline concepts for future
airborne and balloon-based instruments for coronal spectroscopy
and spectro-polarimetry. The airborne infrared spectrometer
(AIR-Spec) was commissioned during the 2017 total solar eclipse,
when it observed five infrared coronal emission lines from the NSF
Gulfstream V research jet. These magnetically sensitive emission lines
of highly ionized magnesium, silicon, sulfur, and iron are promising
candidates for future observations of the coronal magnetic field, and
their characterization is an important first step toward developing
the next generation of instrumentation for coronal magnetometry. The
second AIR-Spec research flight took place during the July 2, 2019
total solar eclipse across the south Pacific. Higher sensitivity and
reduced jitter enabled more precise measurements of emission line
properties and plasma density, temperature, and line-of-sight velocity
up to one solar radius from the solar limb. Atmospheric absorption
was significant, even at altitude, and atmospheric modeling was
required to extract accurate line intensities. AIR-Spec is a slit
spectrometer that measures light over a 1.55 solar radius field of view
in three spectral passbands between 1.4 and 3 microns. The successful
eclipse missions overcame a number of engineering challenges, centered
around maintaining adequate resolution and signal-to-noise ratio in
a compact and inexpensive package on a moving platform. AIR-Spec is a
pathfinder for future infrared spectrometers and spectro-polarimeters,
including a balloon-based coronagraph that will measure the global
coronal magnetic field and an airborne spectrometer that will survey
the infrared emission corona during a future eclipse.

---------------------------------------------------------
Title: Novel observations of the middle corona during the 2017 total
solar eclipse
Authors: Caspi, A.; Seaton, D. B.; Tsang, C.; DeForest, C.; Bryans,
P.; Samra, J.; DeLuca, E.; Tomczyk, S.; Burkepile, J.; Gallagher,
P.; Golub, L.; Judge, P. G.; Laurent, G. T.; West, M.; Zhukov, A.
2019AGUFMSH13A..10C Altcode:
Total solar eclipses offer rare opportunities to study the middle
corona. This intriguing region contains complex interfaces and
transitions between physical regimes, but has historically been
under-observed due to the challenges of observing its dim emission so
close to the bright inner corona and blinding solar disk. The unique
circumstances of a total solar eclipse coupled with a high-altitude
observing platform provide nearly space-quality observing conditions,
including for wavelengths inaccessible by ground-based observatories,
but with availability of ground-quality resources, including high-speed,
high-resolution, wide-field coronography typically inaccessible
from space. We used the 2017 August 21 "Great American" total solar
eclipse to observe the solar corona from ~1.02 to ~3 RSun
in both visible (533.9 ± 4.75 nm) and medium-wave infrared (3-5
μm) light using stabilized telescopes on two of NASA's WB-57F
high-altitude research aircraft. This pathfinding mission utilized
existing instrumentation to evaluate the platform performance, guide
instrumentation development, and explore new discovery space for
future studies of the middle corona. We present the high-speed
(30 Hz), high-resolution (3 arcsec/pixel) visible and IR observations
obtained during the eclipse, and analysis of these observations
in the context of coronal structure and dynamics. We discuss the
limitations of the prototype data and pathways forward for future
instrumentation and missions optimized for the range of observable
parameters in the middle corona. We also discuss the benefits of
such eclipse studies to an understanding of the corona as a single,
unified system, from its origins at the solar surface to its extension
into the heliosphere, particularly within the context of a developing
multi- and inter-disciplinary research collaboration, COHERENT (the
"Corona as a Holistic Environment" Research Network).

---------------------------------------------------------
Title: Unfolding Overlappogram Data: Preparing for the COOL-AID
instrument on Hi-C FLARE
Authors: Winebarger, A. R.; De Pontieu, B.; Cheung, C. M. M.;
Martinez-Sykora, J.; Hansteen, V. H.; Testa, P.; Golub, L.; Savage,
S. L.; Samra, J.; Reeves, K.
2019AGUFMSH33A..06W Altcode:
During a solar flare, energy released in the corona streams to the solar
chromosphere, where plasma is heated and then evaporated upward. The
magnitude of these velocities and their evolution as a function of time
can provide quantitative information on the magnitude of energy released
and the method by which it is transported in a solar flare. Measuring
these velocities, however, is quite challenging. Typically, they are
measured with single slit spectrometers, where light passing through
a long but narrow slit is dispersed and emission lines formed across
a range of temperatures are observed. The main issue with using
single slit spectrometers to make this measurement is that they are
rarely pointed at the right place at the right time. Additionally,
their fields of view are limited by narrow slit widths, and although
rastering can effectively expand the field of view, it does so at the
cost of time. This combination means that single slit spectrometers
cannot adequately capture the evolution of the flare velocities. On
the contrary, slitless spectrometers can make "overlappograms”,
which provide both imaging and spectral information over a large field
of view. However, spatial information from different spectral lines
can overlap in the dispersion direction, making the data difficult
to interpret. Furthermore, the spectral resolution of slitless
spectrometers are limited and typically worse than single-slit
spectrometers, since no line fitting (and hence sub-pixel sampling) is
possible. For the next generation of the High-resolution Coronal
Imager (Hi-C) Rocket Experiment, which we are proposing to launch during
a solar flare, we are including the COronal OverLapagram - Ancillary
Imaging Diagnostics (COOL-AID) instrument. COOL-AID is a slitless
spectrometer based on the COronal Spectrographic Imager in the EUV
(COSIE) design, but with a narrow passband coating around 12.9 nm (the
same passband as the primary Hi-C telescope), a spatial resolution of
~1"x2", and a velocity resolution of ~5 km/s. The goal of the COOL-AID
instrument is to determine the velocity associated with the Fe XXI
12.9 nm spectral line during a solar flare. In this talk, we will
demonstrate the unfolding method developed by Cheung et al (2019) to
determine the velocity information from a simulated COOL-AID data set.

---------------------------------------------------------
Title: Solar Eclipse Observations from the Ground and Air from 0.31
to 5.5 Microns
Authors: Judge, Philip; Berkey, Ben; Boll, Alyssa; Bryans, Paul;
Burkepile, Joan; Cheimets, Peter; DeLuca, Edward; de Toma, Giuliana;
Gibson, Keon; Golub, Leon; Hannigan, James; Madsen, Chad; Marquez,
Vanessa; Richards, Austin; Samra, Jenna; Sewell, Scott; Tomczyk,
Steven; Vera, Alysha
2019SoPh..294..166J Altcode:
We present spectra and broad-band polarized light data from a novel
suite of instruments deployed during the 21st August 2017 total solar
eclipse. Our goals were to survey solar spectra at thermal infrared
wavelengths during eclipse, and to test new technology for measuring
polarized coronal light. An infrared coronal imaging spectrometer,
flown at 14.3 km altitude above Kentucky, was supported on the ground
by observations from Madras, Oregon (elevation 683 m) and Camp Wyoba
on Casper Mountain, Wyoming (2402 m). In Wyoming we deployed a new
infrared Fourier Transform Spectrometer (FTS), three low-dispersion
spectrometers loaned to us by Avantes, a novel visible-light camera
PolarCam, sensitive to linear polarization, and one of two infrared
cameras from FLIR Systems, the other operated at Madras. Circumstances
of eclipse demanded that the observations spanned 17:19 to 18:26
UT. We analyze spectra of the limb photosphere, the chromosphere,
prominences, and coronal lines from 310 nm to 5.5 μm. We calibrated
data photometrically using the solar disk as a source. Between different
spectrometers, the calibrations were consistent to better than 13%. But
the sensitivities achieved were insufficient to detect coronal lines
from the ground. The PolarCam data are in remarkable agreement with
polarization data from the K-Cor synoptic instrument on Mauna Loa, and
with FLIR intensity data acquired in Madras. We discuss new results,
including a detection of the He I 1083 nm multiplet in emission during
the whole of totality. The combination of the FTS and AIR-Spec spectra
reveals for the first time the effects of the telluric extinction
on the infrared coronal emission lines, to be observed with upcoming
Daniel K. Inouye Solar Telescope.

---------------------------------------------------------
Title: Solar Active Region Heating Diagnostics from High-temperature
Emission Using the MaGIXS
Authors: Athiray, P. S.; Winebarger, Amy R.; Barnes, Will T.; Bradshaw,
Stephen J.; Savage, Sabrina; Warren, Harry P.; Kobayashi, Ken; Champey,
Patrick; Golub, Leon; Glesener, Lindsay
2019ApJ...884...24A Altcode: 2019arXiv190902541A
The relative amount of high-temperature plasma has been found to be
a useful diagnostic to determine the frequency of coronal heating on
sub-resolution structures. When the loops are infrequently heated,
a broad emission measure (EM) over a wider range of temperatures
is expected. A narrower EM is expected for high-frequency heating
where the loops are closer to equilibrium. The soft X-ray spectrum
contains many spectral lines that provide high-temperature diagnostics,
including lines from Fe XVII-XIX. This region of the solar spectrum
will be observed by the Marshall Grazing Incidence Spectrometer (MaGIXS)
in 2020. In this paper, we derive the expected spectral line intensity
in MaGIXS to varying amounts of high-temperature plasma to demonstrate
that a simple line ratio provides a powerful diagnostic to determine
the heating frequency. Similarly, we examine ratios of AIA channel
intensities, filter ratios from a XRT, and energy bands from the FOXSI
sounding rocket to determine their sensitivity to this parameter. We
find that both FOXSI and MaGIXS provide good diagnostic capabilities
for high-temperature plasma. We then compare the predicted line ratios
to the output of a numerical model and confirm that the MaGIXS ratios
provide an excellent diagnostic for heating frequency.

---------------------------------------------------------
Title: State of the Profession Considerations for Laboratory
Astrophysics
Authors: Savin, Daniel Wolf; Babb, James F.; Barklem, Paul; Bellan,
Paul M.; Betancourt-Martinez, Gabriele; Blum, Jürgen; Boersma,
Christiaan; Boryta, Mark D.; Brisset, Julie; Brogan, Crystal; Cami,
Jan; Caselli, Paola; Chutjian, Ara; Corrales, Lia; Crabtree, Kyle;
Dominguez, Gerardo; Federman, Steven R.; Fontes, Christopher J.;
Freedman, Richard; Gavilan-Marin, Lisseth; Gibson, Brad; Golub, Leon;
Gorczyca, Thomas W.; Hahn, Michael; Hartmann, Dieter; Hörst, Sarah M.;
Hudson, Reggie L.; Ji, Hantao; Kreckel, Holger; Kuhn, Jeffrey; Lawler,
James E.; Lee, Timothy J.; Leutenegger, Maurice A.; Mancini, Roberto;
Marler, Joan P.; Mashonkina, Lyudmila I.; McCarthy, Michael C.;
McCoustra, Martin; McGuire, Brett A.; Milam, Stefanie N.; Montgomery,
Mike; Murphy, Nicholas A.; Nave, Gillian; Nelson, Robert M.; Nollett,
Kenneth M.; Norton, Aimee A.; Novotný, Oldřich; Papol, Anthony;
Raymond, John C.; Salama, Farid; Sciamma-O'Brien, Ella M.; Smith,
Randall; Sosolik, Chad; Sousa-Silva, Clara; Spyrou, Artemis; Stancil,
Phillip C.; Sung, Keeyoon; Tennyson, Jonathan; Timmes, Frank; Trimble,
Virginia L.; Venot, Olivia; Wahlgren, Glenn; Wargelin, Bradford J.;
Winget, Don; Wood, Michael P.
2019BAAS...51g...7S Altcode: 2019astro2020U...7S
Astrophysics advances, in part, through laboratory astrophysics studies
of the underlying processes controlling the observed properties of
the Cosmos. These studies encompass both theoretical and experimental
research. Robust support for laboratory astrophysics is critically
needed to maximize the scientific return of astronomical observations.

---------------------------------------------------------
Title: Unfolding Overlapped Slitless Imaging Spectrometer Data for
Extended Sources
Authors: Winebarger, Amy R.; Weber, Mark; Bethge, Christian; Downs,
Cooper; Golub, Leon; DeLuca, Edward; Savage, Sabrina; del Zanna,
Giulio; Samra, Jenna; Madsen, Chad; Ashraf, Afra; Carter, Courtney
2019ApJ...882...12W Altcode: 2018arXiv181108329W
Slitless spectrometers can provide simultaneous imaging and spectral
data over an extended field of view, thereby allowing rapid data
acquisition for extended sources. In some instances, when the object
is greatly extended or the spectral dispersion is too small, there
may be locations in the focal plane where emission lines at different
wavelengths contribute. It is then desirable to unfold the overlapped
regions in order to isolate the contributions from the individual
wavelengths. In this paper, we describe a method for such an unfolding,
using an inversion technique developed for an extreme ultraviolet
imaging spectrometer and coronagraph named the COronal Spectroscopic
Imager in the EUV (COSIE). The COSIE spectrometer wavelength range
(18.6-20.5 nm) contains a number of strong coronal emission lines and
several density sensitive lines. We focus on optimizing the unfolding
process to retrieve emission measure maps at constant temperature,
maps of spectrally pure intensity in the Fe XII and Fe XIII lines,
and density maps based on both Fe XII and Fe XIII diagnostics.

---------------------------------------------------------
Title: Investigating Coronal Magnetism with COSMO: Science on
the Critical Path To Understanding The “Weather” of Stars and
Stellarspheres
Authors: McIntosh, Scott; Tomczyk, Steven; Gibson, Sarah E.; Burkepile,
Joan; de Wijn, Alfred; Fan, Yuhong; deToma, Giuliana; Casini, Roberto;
Landi, Enrico; Zhang, Jie; DeLuca, Edward E.; Reeves, Katharine K.;
Golub, Leon; Raymond, John; Seaton, Daniel B.; Lin, Haosheng
2019BAAS...51g.165M Altcode: 2019astro2020U.165M
The Coronal Solar Magnetism Observatory (COSMO) is a unique ground-based
facility designed to address the shortfall in our capability to measure
magnetic fields in the solar corona.

---------------------------------------------------------
Title: Signatures of the non-Maxwellian κ-distributions in optically
thin line spectra. II. Synthetic Fe XVII-XVIII X-ray coronal spectra
and predictions for the Marshall Grazing-Incidence X-ray Spectrometer
(MaGIXS)
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Del Zanna, Giulio;
Mason, Helen E.; Golub, Leon L.; Winebarger, Amy R.; Savage, Sabrina L.
2019A&A...626A..88D Altcode: 2019arXiv190510356D
 Aims: We investigated the possibility of diagnosing the degree of
departure from the Maxwellian distribution using the Fe XVII-Fe XVIII
spectra originating in plasmas in collisional ionization equilibrium,
such as in the cores of solar active regions or microflares. 
Methods: The original collision strengths for excitation are integrated
over the non-Maxwellian electron κ-distributions characterized by a
high-energy tail. Synthetic X-ray emission line spectra were calculated
for a range of temperatures and κ. We focus on the 6-24 Å spectral
range to be observed by the upcoming Marshall Grazing-Incidence X-ray
Spectrometer MaGIXS. Results: We find that many line intensity
ratios are sensitive to both T and κ. Best diagnostic options are
provided if a ratio involving both Fe XVII and Fe XVIII is combined
with another ratio involving lines formed within a single ion. The
sensitivity of such diagnostics to κ is typically a few tens of per
cent. Much larger sensitivity, of about a factor of two to three, can
be obtained if the Fe XVIII 93.93 Å line observed by SDO/AIA is used
in conjuction with the X-ray lines. Conclusions: We conclude
that the MaGIXS instrument is well-suited for detection of departures
from the Maxwellian distribution, especially in active region cores.

---------------------------------------------------------
Title: Astrophysical Science enabled by Laboratory Astrophysics
Studies in Atomic, Molecular, and Optical (AMO) Physics
Authors: Savin, Daniel Wolf; Babb, James F.; Bellan, Paul M.; Brogan,
Crystal; Cami, Jan; Caselli, Paola; Corrales, Lia; Dominguez, Gerardo;
Federman, Steven R.; Fontes, Chris J.; Freedman, Richard; Gibson,
Brad; Golub, Leon; Gorczyca, Thomas W.; Hahn, Michael; Hartmann,
Dieter; Hörst, Sarah M.; Hudson, Reggie L.; Kuhn, Jeffrey; Lawler,
James E.; Leutenegger, Maurice A.; Marler, Joan P.; McCarthy, Michael
C.; McGuire, Brett A.; Milam, Stefanie N.; Murphy, Nicholas A.; Nave,
Gillian; Norton, Aimee A.; Papol, Anthony; Raymond, John C.; Salama,
Farid; Sciamma-O'Brien, Ella M.; Smith, Randall; Sosolik, Chad;
Sousa-Silva, Clara; Stancil, Phillip C.; Timmes, Frank; Trimble,
Virginia L.; Wargelin, Bradford J.
2019BAAS...51c..96S Altcode: 2019astro2020T..96S
We highlight a few of the many astrophysical advances that will become
possible with advances in AMO laboratory astrophysics. This submission
supersedes the previous submission.

---------------------------------------------------------
Title: COSMO Science
Authors: Gibson, Sarah; Tomczyk, Steven; Burkepile, Joan; Casini,
Roberto; Deluca, Ed; de Toma, Giuliana; deWijn, Alfred; Fan, Yuhong;
Golub, Leon; Judge, Philip; Landi, Enrico; Lin, Haosheng; McIntosh,
Scott; Reeves, Kathy; Seaton, Dan; Zhang, Jie
2019shin.confE..32G Altcode:
Space-weather forecast capability is held back by our current
lack of basic scientific understanding of CME magnetic evolution,
and the coronal magnetism that structures and drives the solar
wind. Comprehensive observations of the global magnetothermal
environment of the solar atmosphere are needed for progress. When fully
implemented, the COSMO suite of synoptic ground-based telescopes will
provide the community with comprehensive and simultaneous measurements
of magnetism, temperature, density and plasma flows and waves from the
photosphere through the chromosphere and out into the corona. We will
discuss how these observations will uniquely address a set of science
objectives that are central to the field of solar and space physics:
in particular, to understand the storage and release of magnetic energy,
to understand CME dynamics and consequences for shocks, to determine the
role of waves in solar atmospheric heating and solar wind acceleration,
to understand how the coronal magnetic field relates to the solar
dynamo, and to constrain and improve space-weather forecast models.

---------------------------------------------------------
Title: Solar Coronal Structure: Loops, Clouds, or Both?
Authors: Golub, Leon; Asgari-Targhi, Mahboubeh; Coppi, Bruno; Basu,
Bamandas
2019RNAAS...3....4G Altcode: 2019RNAAS...3a...4G
No abstract at ADS

---------------------------------------------------------
Title: Perspectives on Astrophysics Based on Atomic, Molecular,
and Optical (AMO) Techniques
Authors: Savin, Daniel Wolf; Babb, James F.; Bellan, Paul M.; Brogan,
Crystal; Cami, Jan; Caselli, Paola; Corrales, Lia; Dominguez, Gerardo;
Federman, Steven R.; Fontes, Chris J.; Freedman, Richard; Gibson,
Brad; Golub, Leon; Gorczyca, Thomas W.; Hahn, Michael; Hörst, Sarah
M.; Hudson, Reggie L.; Kuhn, Jeffrey; Lawler, James E.; Leutenegger,
Maurice A.; Marler, Joan P.; McCarthy, Michael C.; McGuire, Brett A.;
Milam, Stefanie N.; Murphy, Nicholas A.; Nave, Gillian; Norton, Aimee
A.; Papol, Anthony; Raymond, John C.; Salama, Farid; Sciamma-O'Brien,
Ella M.; Smith, Randall; Sosolik, Chad; Sousa-Silva, Clara; Stancil,
Phillip C.; Timmes, Frank; Trimble, Virginia L.; Wargelin, Bradford J.
2018arXiv181106157S Altcode:
About two generations ago, a large part of AMO science was dominated by
experimental high energy collision studies and perturbative theoretical
methods. Since then, AMO science has undergone a transition and is now
dominated by quantum, ultracold, and ultrafast studies. But in the
process, the field has passed over the complexity that lies between
these two extremes. Most of the Universe resides in this intermediate
region. We put forward that the next frontier for AMO science is to
explore the AMO complexity that describes most of the Cosmos.

---------------------------------------------------------
Title: Book Review: The Sun
Authors: Golub, Leon; Pasachoff, Jay M.
2018JAHH...21..241C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Predicting the COSIE-C Signal from the Outer Corona up to 3
Solar Radii
Authors: Del Zanna, Giulio; Raymond, John; Andretta, Vincenzo; Telloni,
Daniele; Golub, Leon
2018ApJ...865..132D Altcode: 2018arXiv180807951D
We present estimates of the signal to be expected in quiescent solar
conditions, as would be obtained with the COronal Spectrographic
Imager in the EUV in its coronagraphic mode (COSIE-C). COSIE-C has been
proposed to routinely observe the relatively unexplored outer corona,
where we know that many fundamental processes affecting both the lower
corona and the solar wind are taking place. The COSIE-C spectral band,
186-205 Å, is well-known as it has been observed with Hinode EIS. We
present Hinode EIS observations that we obtained in 2007 out to 1.5 R
⊙, to show that this spectral band in quiescent streamers
is dominated by Fe XII and Fe XI and that the ionization temperature
is nearly constant. To estimate the COSIE-C signal in the 1.5-3.1
R ⊙ region we use a model based on CHIANTI atomic data
and SoHO UVCS observations in the Si XII and Mg X coronal lines of
two quiescent 1996 streamers. We reproduce the observed EUV radiances
with a simple density model, photospheric abundances, and a constant
temperature of 1.4 MK. We show that other theoretical or semi-empirical
models fail to reproduce the observations. We find that the coronal
COSIE-C signal at 3 R ⊙ should be about 5 counts/s per
3.″1 pixel in quiescent streamers. This is unprecedented and opens
up a significant discovery space. We also briefly discuss stray light
and the visibility of other solar features. In particular, we present
UVCS observations of an active region streamer, indicating increased
signal compared to the quiet Sun cases.

---------------------------------------------------------
Title: Polar Coronal Plumes as Tornado-like Jets
Authors: Tavabi, E.; Koutchmy, S.; Golub, L.
2018ApJ...866...35T Altcode: 2018arXiv180807322T
We examine the dynamical behavior of white-light polar-plume
structures in the inner corona that are observed from the ground
during total solar eclipses, based on their extreme ultraviolet (EUV)
hot and cool emission line counterparts observed from space. EUV
observations from Solar Dynamics Observatory/Atmospheric Imaging
Assembly (SDO/AIA) of a sequence of rapidly varying coronal hole
structures are analyzed. Evidence of events showing acceleration in
the 1.25 Mk line of Fe XII at 193 Å is given. The structures along
the plume show an outward velocity of about 140 km s-1
that can be interpreted as an upward propagating wave in the 304 Å
and 171 Å lines; higher speeds are seen in 193 Å (up to 1000 km
s-1). The ejection of the cold He II plasma is delayed
by about 4 minutes in the lowest layer and is delayed more than 12
minutes in the highest level compared to the hot 193 Å behavior. A
study of the dynamics using time-slice diagrams reveals that a large
amount of fast ejected material originates from below the plume, at
the footpoints. The release of plasma material appears to come from
a cylinder with quasi-parallel edge-enhanced walls. After the initial
phase of a longitudinal acceleration, the speed substantially reduces,
and the ejecta disperse into the environment. Finally, the detailed
temporal and spatial relationships between the cool and hot components
were studied with simultaneous multiwavelength observations, using
more AIA data. The outward-propagating perturbation of the presumably
magnetic walls of polar plumes supports the suggestion that Alfvén
waves propagate outwardly along these radially extended walls.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Kobayashi, Ken; Winebarger, Amy R.; Savage, Sabrina; Champey,
Patrick; Cheimets, Peter N.; Hertz, Edward; Bruccoleri, Alexander R.;
Scholvin, Jorg; Golub, Leon; Ramsey, Brian; Ranganathan, Jaganathan;
Marquez, Vanessa; Allured, Ryan; Parker, Theodore; Heilmann, Ralf K.;
Schattenburg, Mark L.
2018SPIE10699E..27K Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA
sounding rocket instrument designed to obtain spatially resolved
soft X-ray spectra of the solar atmosphere in the 6-24 Å (0.5-2.0
keV) range. The instrument consists of a single shell Wolter Type-I
telescope, a slit, and a spectrometer comprising a matched pair of
grazing incidence parabolic mirrors and a planar varied-line space
diffraction grating. The instrument is designed to achieve a 50
mÅ spectral resolution and 5 arcsecond spatial resolution along a
+/-4-arcminute long slit, and launch is planned for 2019. We report
on the status and our approaches for fabrication and alignment for
this novel optical system. The telescope and spectrometer mirrors are
replicated nickel shells, and are currently being fabricated at the
NASA Marshall Space Flight Center. The diffraction grating is currently
under development by the Massachusetts Institute of Technology (MIT);
because of the strong line spacing variation across the grating,
it will be fabricated through e-beam lithography.

---------------------------------------------------------
Title: Eclipse Science from 50,000 Feet: New Coronal Results from
NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total
Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; Seaton, Daniel B.; DeForest,
Craig; Bryans, Paul; DeLuca, Edward; Tomczyk, Steven; Burkepile,
Joan; Casey, Thomas Anthony; Collier, John; Darrow, Donald DD; Del
Rosso, Dominic; Durda, Daniel D.; Gallagher, Peter; Gascar, Jasmine;
Golub, Leon; Jacyna, Matthew; Johnson, David DJ; Judge, Philip G.;
Klemm, Cary; Laurent, Glenn Thomas; Lewis, Johanna; Mallini, Charles;
Parent, Thomas Duster; Propp, Timothy; Steffl, Andrew; Warner, Jeff;
West, Matthew John; Wiseman, John; Yates, Mallory; Zhukov, Andrei
2018tess.conf31302C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface. Studying the corona is critical to gaining
a better understanding of the dominant driver of space weather that
affects human assets on Earth and elsewhere. For example, it is still
poorly understood how the corona is heated to temperatures of 1-2 MK
globally and up to 5-10 MK above active regions, while the underlying
chromosphere is 100 times cooler. The stability of large-scale coronal
structures and the extent of their reach to the middle and outer corona
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations
during a total eclipse provide unique advantages. By flying in the
stratosphere at altitudes of 50 kft or higher, they avoid all weather,
the seeing quality is enormously improved, and additional wavelengths
such as near-IR also become available due to significantly reduced
water absorption. An airborne observatory can also follow the Moon's
shadow, increasing the total observing time by 50% or more. We
present current results of solar coronal measurements from airborne
observations of the 2017 Great American Total Solar Eclipse using two
of NASA's WB-57 high-altitude research aircraft, each equipped with
two 8.7-inch telescopes feeding high-sensitivity visible (green line
and nearby continuum) and medium-wave IR (3-5 μm) cameras operating
at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3
Rsun fields of view. The two aircraft flew along the eclipse
path, separated by ∼110 km, to observe a total of ∼7.5 minutes
of totality in both visible and MWIR. These observations enable
groundbreaking studies of high-speed coherent motion - including
possible Alfvén waves and nanojets - in the lower and middle corona
that could shed light on coronal heating processes and the formation
and stability of coronal structures. Our MWIR observations of a cool
prominence and hot coronal active region plasma will be combined with
spectra from the AIR-Spec instrument, flown concurrently on NCAR's
HIAPER GV. We review the WB-57 eclipse mission and the current results
of analysis on the visible and IR coronal measurements, along with an
outlook for future analysis and missions.

---------------------------------------------------------
Title: Using DSG to build the capability of space weather forecasting
in deep space.
Authors: DeLuca, Edward; Golub, Leon; Korreck, Kelly; Savage, Sabrina
L.; McKenzie, David E.; Rachmeler, Laurel; Winebarger, Amy R.; Martens,
Petrus C.
2018tess.conf22002D Altcode:
The prospect of astronaut missions to deep space and off the
sun-earth line raises new challenges for space weather awareness
and forecasting. Combined efforts of the science and human flight
communities are needed to identify the requirements and identify
pathways that will allow us to address the requirements for protecting
human life and equipment, on a timescale consistent with the deep space
exploration program. &lt;p class="p1" The Deep Space Gateway provides
a platform where we can develop, test and validate a combined space
weather instrumentation, analysis and forecasting system that can be
used when out of routine contact with near earth based assets. This
presentation will attempt to outline the bounds of the problem and start
the discussion about how to build an independent space weather program.

---------------------------------------------------------
Title: Editorial: Data: Insights and Challenges in a Time of Abundance
Authors: Timmes, Frank; Golub, Leon
2018ApJS..236....1T Altcode:
No abstract at ADS

---------------------------------------------------------
Title: CisLunar Interchangeable Observatory for Heliophysics (CLIOH):
A Deep Space Gateway Solar Viewing Platform for Technology Development
and Research Payloads
Authors: Savage, S.; DeLuca, E.; Cheimets, P.; Golub, L.; Kobayashi,
K.; McKenzie, D.; Rachmeler, L.; Winebarger, A.
2018LPICo2063.3061S Altcode:
The Deep Space Gateway offers an unparalleled opportunity to test
and operate solar instrumentation in a radiation hard environment,
which can be achieved via an external pointing platform designed to
accommodate multiple interchangeable payloads.

---------------------------------------------------------
Title: Using DSG to Build the Capability of Space Weather Forecasting
in Deep Space
Authors: DeLuca, E. E.; Golub, L.; Korreck, K.; Savage, S.; McKenzie,
D. D.; Rachmeler, L.; Winebarger, A.; Martens, P.
2018LPICo2063.3050D Altcode:
The prospect of astronaut missions to deep space and off the
Sun-Earth line raises new challenges for space weather awareness and
forecasting. We need to identify the requirements and pathways that
will allow us to protect human life and equipment.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Winebarger, A. R.; Savage, S. L.; Kobayashi, K.; Champey,
P. R.; McKenzie, D. E.; Golub, L.; Testa, P.; Reeves, K.; Cheimets,
P.; Cirtain, J. W.; Walsh, R. W.; Bradshaw, S. J.; Warren, H.; Mason,
H. E.; Del Zanna, G.
2017AGUFMSH44A..06W Altcode:
For over four decades, X-ray, EUV, and UV spectral observations have
been used to measure physical properties of the solar atmosphere. At
wavelengths below 10 nm, however, observations of the solar corona
with simultaneous spatial and spectral resolution are limited,
and not since the late 1970's have spatially resolved solar X-ray
spectra been measured. Because the soft X-ray regime is dominated
by emission lines formed at high temperatures, X-ray spectroscopic
techniques yield insights to fundamental physical processes that are
not accessible by any other means. Using a novel implementation of
corrective optics, the Marshall Grazing Incidence X-ray Spectrometer
(MaGIXS) will measure, for the first time, the solar spectrum from 0.6-
2.4 nm with a 6 arcsec resolution over an 8 arcmin slit. The MaGIXS
mission will address on of the fundamental problems of coronal physics:
the nature of coronal heating. There are several observables in the
MaGIXS wavelength range that will constrain the heating frequency and
hence discriminate between competing coronal heating theories. In this
presentation, we will present the MaGIXS scientific motivation and
provide an update on instrument development. MaGIXS will be launched
from White Sands Missile Range in the summer of 2019.

---------------------------------------------------------
Title: Chasing the Great American 2017 Total Solar Eclipse: Coronal
Results from NASA's WB-57F High-Altitude Research Aircraft
Authors: Caspi, A.; Tsang, C.; DeForest, C. E.; Seaton, D. B.; Bryans,
P.; Burkepile, J.; Casey, T. A.; Collier, J.; Darrow, D.; DeLuca,
E.; Durda, D. D.; Gallagher, P.; Golub, L.; Judge, P. G.; Laurent,
G. T.; Lewis, J.; Mallini, C.; Parent, T.; Propp, T.; Steffl, A.;
Tomczyk, S.; Warner, J.; West, M. J.; Wiseman, J.; Zhukov, A.
2017AGUFMSH24A..05C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such as
near- IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more. We present
results of solar coronal measurements from airborne observations of
the 2017 Great American Total Solar Eclipse using two of NASA's WB-57
high-altitude research aircraft, each equipped with two 8.7" telescopes
feeding high-sensitivity visible (green-line) and medium-wave IR (3-5
μm) cameras operating at high cadence (30 Hz) with 3 arcsec/pixel
platescale and ±3 R_sun fields of view. The aircraft flew along the
eclipse path, separated by 110 km, to observe a summed 7.5 minutes of
totality in both visible and NIR, enabling groundbreaking studies of
high-speed wave motions and nanojets in the lower corona, the structure
and extent of coronal fans, and constraints on a potential primordial
dust ring around the Sun. We review the mission, and the results of
analysis on the visible and IR coronal measurements.

---------------------------------------------------------
Title: ASPIRE - Airborne Spectro-Polarization InfraRed Experiment
Authors: DeLuca, E.; Cheimets, P.; Golub, L.; Madsen, C. A.; Marquez,
V.; Bryans, P.; Judge, P. G.; Lussier, L.; McIntosh, S. W.; Tomczyk, S.
2017AGUFMSH13B2480D Altcode:
Direct measurements of coronal magnetic fields are critical for
taking the next step in active region and solar wind modeling and
for building the next generation of physics-based space-weather
models. We are proposing a new airborne instrument to make these key
observations. Building on the successful Airborne InfraRed Spectrograph
(AIR-Spec) experiment for the 2017 eclipse, we will design and build a
spectro-polarimeter to measure coronal magnetic field during the 2019
South Pacific eclipse. The new instrument will use the AIR-Spec optical
bench and the proven pointing, tracking, and stabilization optics. A new
cryogenic spectro-polarimeter will be built focusing on the strongest
emission lines observed during the eclipse. The AIR-Spec IR camera,
slit jaw camera and data acquisition system will all be reused. The
poster will outline the optical design and the science goals for ASPIRE.

---------------------------------------------------------
Title: Endogenous Magnetic Reconnection in Solar Coronal Loops
Authors: Asgari-Targhi, M.; Coppi, B.; Basu, B.; Fletcher, A.;
Golub, L.
2017AGUFMSH11A2420A Altcode:
We propose that a magneto-thermal reconnection process occurring in
coronal loops be the source of the heating of the Solar Corona [1]. In
the adopted model, magnetic reconnection is associated with electron
temperature gradients, anisotropic electron temperature fluctuations
and plasma current density gradients [2]. The input parameters for our
theoretical model are derived from the most recent observations of
the Solar Corona. In addition, the relevant (endogenous) collective
modes can produce high energy particle populations. An endogenous
reconnection process is defined as being driven by factors internal
to the region where reconnection takes place. *Sponsored in part by
the U.S. D.O.E. and the Kavli Foundation* [1] Beafume, P., Coppi,
B. and Golub, L., (1992) Ap. J. 393, 396. [2] Coppi, B. and Basu,
B. (2017) MIT-LNS Report HEP 17/01.

---------------------------------------------------------
Title: Eclipse Science Results from the Airborne Infrared Spectrometer
(AIR-Spec)
Authors: Samra, J.; Cheimets, P.; DeLuca, E.; Golub, L.; Judge, P. G.;
Lussier, L.; Madsen, C. A.; Marquez, V.; Tomczyk, S.; Vira, A.
2017AGUFMSH24A..06S Altcode:
We present the first science results from the commissioning flight
of the Airborne Infrared Spectrometer (AIR-Spec), an innovative
solar spectrometer that will observe the 2017 solar eclipse from
the NSF/NCAR High-Performance Instrumented Airborne Platform for
Environmental Research (HIAPER). During the eclipse, AIR-Spec will
image five magnetically sensitive coronal emission lines between 1.4
and 4 microns to determine whether they may be useful probes of coronal
magnetism. The instrument will measure emission line intensity, FWHM,
and Doppler shift from an altitude of over 14 km, above local weather
and most of the absorbing water vapor. Instrumentation includes an image
stabilization system, feed telescope, grating spectrometer, infrared
camera, and visible slit-jaw imager. Results from the 2017 eclipse
are presented in the context of the mission's science goals. AIR-Spec
will identify line strengths as a function of position in the solar
corona and search for the high frequency waves that are candidates
for heating and acceleration of the solar wind. The instrument will
also identify large scale flows in the corona, particularly in polar
coronal holes. Three of the five lines are expected to be strong in
coronal hole plasmas because they are excited in part by scattered
photospheric light. Line profile analysis will probe the origins
of the fast and slow solar wind. Finally, the AIR-Spec measurements
will complement ground based eclipse observations to provide detailed
plasma diagnostics throughout the corona. AIR-Spec will measure infrared
emission of ions observed in the visible from the ground, giving insight
into plasma heating and acceleration at radial distances inaccessible
to existing or planned spectrometers.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer
Authors: Kobayashi, Ken; Winebarger, Amy R.; Savage, Sabrina; Champey,
Patrick; Cheimets, Peter N.; Hertz, Edward; Bruccoleri, Alexander R.;
Golub, Leon; Ramsey, Brian; Ranganathan, Jaganathan; Marquez, Vanessa;
Allured, Ryan; Parker, Theodore; Heilmann, Ralf K.; Schattenburg,
Mark L.
2017SPIE10397E..1IK Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA
sounding rocket instrument designed to obtain spatially resolved
soft X-ray spectra of the solar atmosphere in the 6-24 Å (0.5-2.0
keV) range. The instrument consists of a single shell Wolter Type-I
telescope, a slit, and a spectrometer comprising a matched pair of
grazing incidence parabolic mirrors and a planar varied-line space
diffraction grating. The instrument is designed to achieve a 50
mÅ spectral resolution and 5 arcsecond spatial resolution along a
+/-4-arcminute long slit, and launch is planned for 2019. We report
on the status and our approaches for fabrication and alignment for
this novel optical system. The telescope and spectrometer mirrors are
replicated nickel shells, and are currently being fabricated at the
NASA Marshall Space Flight Center. The diffraction grating is currently
under development by the Massachusetts Institute of Technology (MIT);
because of the strong line spacing variation across the grating,
it will be fabricated through e-beam lithography.

---------------------------------------------------------
Title: First results from the NASA WB-57 airborne observations of
the Great American 2017 Total Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; DeForest, Craig; Seaton,
Daniel B.; Bryans, Paul; Tomczyk, Steven; Burkepile, Joan; Judge,
Phil; DeLuca, Edward E.; Golub, Leon; Gallagher, Peter T.; Zhukov,
Andrei; West, Matthew; Durda, Daniel D.; Steffl, Andrew J.
2017SPD....4810701C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations.Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such
as near-IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more.We present
the first results from airborne observations of the 2017 Great American
Total Solar Eclipse using two of NASA's WB-57 research aircraft, each
equipped with two 8.7" telescopes feeding high-sensitivity visible
(green-line) and near-IR (3-5 µm) cameras operating at high cadence
(30 Hz) with ~3 arcsec/pixel platescale and ±3 R_sun fields of
view. The aircraft will fly along the eclipse path, separated by ~90
km, to observe a summed ~8 minutes of totality in both visible and
NIR, enabling groundbreaking studies of high-speed wave motions and
nanojets in the lower corona, the structure and extent of coronal fans,
and constraints on a potential primordial dust ring around the Sun.

---------------------------------------------------------
Title: Solving the Coronal Heating Problem using X-ray
Microcalorimeters
Authors: Christe, Steven; Bandler, Simon; DeLuca, Edward; Caspi,
Amir; Golub, Leon; Smith, Randall; Allred, Joel; Brosius, Jeffrey W.;
Dennis, Brian; Klimchuk, James
2017arXiv170100795C Altcode:
Even in the absence of resolved flares, the corona is heated to several
million degrees. However, despite its importance for the structure,
dynamics, and evolution of the solar atmosphere, the origin of this
heating remains poorly understood. Several observational and theoretical
considerations suggest that the heating is driven by small, impulsive
energy bursts which could be Parker-style "nanoflares" (Parker 1988)
that arise via reconnection within the tangled and twisted coronal
magnetic field. The classical "smoking gun" (Klimchuk 2009; Cargill et
al. 2013) for impulsive heating is the direct detection of widespread
hot plasma (T &gt; 6 MK) with a low emission measure. In recent years
there has been great progress in the development of Transition Edge
Sensor (TES) X-ray microcalorimeters that make them more ideal for
studying the Sun. When combined with grazing-incidence focusing optics,
they provide direct spectroscopic imaging over a broad energy band
(0.5 to 10 keV) combined with extremely impressive energy resolution
in small pixels, as low as 0.7 eV (FWHM) at 1.5 keV (Lee 2015),
and 1.56 eV (FWHM) at 6 keV (Smith 2012), two orders of magnitude
better than the current best traditional solid state photon-counting
spectrometers. Decisive observations of the hot plasma associated
with nanoflare models of coronal heating can be provided by new solar
microcalorimeters. These measurements will cover the most important part
of the coronal spectrum for searching for the nanoflare-related hot
plasma and will characterize how much nanoflares can heat the corona
both in active regions and the quiet Sun. Finally, microcalorimeters
will enable to study all of this as a function of time and space in
each pixel simultaneously a capability never before available.

---------------------------------------------------------
Title: MWA Observations of Solar Radio Bursts and the Quiet Sun
Authors: Cairns, I.; Oberoi, D.; Morgan, J.; Bastian, T.; Bhatnagar,
S.; Bisi, M.; Benkevitch, L.; Bowman, J.; Donea, A.; Giersch, O.;
Jackson, B.; Chat, G. L.; Golub, L.; Hariharan, K.; Herne, D.; Kasper,
J.; Kennewell, J.; Lonsdale, C.; Lobzin, V.; Matthews, L.; Mohan, A.;
Padmanabhan, J.; Pankratius, V.; Pick, M.; Subramanian, P.; Ramesh,
R.; Raymond, J.; Reeves, K.; Rogers, A.; Sharma, R.; Tingay, S.;
Tremblay, S.; Tripathi, D.; Webb, D.; White, S.; Abidin, Z. B. Z.
2017mwa..prop..A06C Altcode:
A hundred hours of observing time for solar observations is requested
during the 2017-A observing semester. These data will be used to address
science objectives for solar burst science (Goal A), studies of weak
non-thermal radiation (Goal B) and quiet sun science (Goal C). Goal
A will focus on detailed investigations of individual events seen in
the MWA data, using the unsurpassed spectroscopic imaging ability
of the MWA to address some key solar physics questions. Detailed
observations of type II bursts, of which MWA has observed two, will
be one focus, with MWA polarimetric imaging observations of type III
bursts another focus. Goal B will address studies of the numerous
short lived and narrow band emission features, significantly weaker
than those seen by most other instruments revealed by the MWA. These
emission features do not resemble any known types of solar bursts, but
are possible signatures of "nanoflares" which have long been suspected
to play a role in coronal heating. A large database of these events is
needed to be able to reliably estimate their contribution to coronal
heating. These observations will contribute to this database. Goal C
will focus on characterizing the Sun's background thermal emission,
their short and long term variability and looking for evidence of a
scattering disc around the Sun.

---------------------------------------------------------
Title: Development of the User Interface for AIR-Spec
Authors: Cervantes Alcala, E.; Guth, G.; Fedeler, S.; Samra, J.;
Cheimets, P.; DeLuca, E.; Golub, L.
2016AGUFMSM51A2458C Altcode:
The airborne infrared spectrometer (AIR-Spec) is an imaging
spectrometer that will observe the solar corona during the 2017 total
solar eclipse. This eclipse will provide a unique opportunity to
observe infrared emission lines in the corona. Five spectral lines
are of particular interest because they may eventually be used to
measure the coronal magnetic field. To avoid infrared absorption from
atmospheric water vapor, AIR-Spec will be placed on an NSF Gulfstream
aircraft flying above 14.9 km. AIR-Spec must be capable of taking
stable images while the plane moves. The instrument includes an image
stabilization system, which uses fiber-optic gyroscopes to determine
platform rotation, GPS to calculate the ephemeris of the sun, and
a voltage-driven mirror to correct the line of sight. An operator
monitors a white light image of the eclipse and manually corrects
for residual drift. The image stabilization calculation is performed
by a programmable automatic controller (PAC), which interfaces with
the gyroscopes and mirror controller. The operator interfaces with
a separate computer, which acquires images and computes the solar
ephemeris. To ensure image stabilization is successful, a human machine
interface (HMI) was developed to allow connection between the client
and PAC. In order to make control of the instruments user friendly
during the short eclipse observation, a graphical user interface
(GUI) was also created. The GUI's functionality includes turning
image stabilization on and off, allowing the user to input information
about the geometric setup, calculating the solar ephemeris, refining
estimates of the initial aircraft attitude, and storing data from
the PAC on the operator's computer. It also displays time, location,
attitude, ephemeris, gyro rates and mirror angles.

---------------------------------------------------------
Title: COSIE: A Wide-field EUV Imager and Spectrograph for the ISS
Authors: Golub, L.; Savage, S. L.
2016AGUFMSH31C..08G Altcode:
We propose a novel dual-use EUV imager designed to observe the dynamics
of the solar corona from the solar surface out to 3 R_sol. The COSIE
instrument is proposed as an MoO within the SMEX program, with the
objectives of: 1.) understanding the dynamics of the Transition Corona,
the region of the upper corona in which the plasma beta changes from
low to high and the atmosphere transitions from being dominated by
magnetically confined closed structures to high beta with generally
open radially-directed regions with outflowing solar wind streams;
2.) providing new tools for space weather forecasting via early
detection of coronal mass ejections (CMEs), determination of early
acceleration and path changes, and modelling of the CME magnetic
configuration at event initiation. The observing mode is switchable via
a mechanism that switches between ultra-high sensitivity direct imaging
and a spectroscopic imaging mode with the goal of understanding the
dynamics of the evolving CME structure and of high temperature plasma
above and around active regions. COSIE is intended to mount to the ISS,
tracking the Sun continuously during its daylight passes.

---------------------------------------------------------
Title: The importance of high-resolution observations of the solar
corona
Authors: Winebarger, A. R.; Cirtain, J. W.; Golub, L.; Walsh, R. W.;
De Pontieu, B.; Savage, S. L.; Rachmeler, L.; Kobayashi, K.; Testa,
P.; Brooks, D.; Warren, H.; Mcintosh, S. W.; Peter, H.; Morton, R. J.;
Alexander, C. E.; Tiwari, S. K.
2016AGUFMSH31B2577W Altcode:
The spatial and temporal resolutions of the available coronal
observatories are inadequate to resolve the signatures of coronal
heating. High-resolution and high-cadence observations available with
the Interface Region Imaging Spectrograph (IRIS) and the High-resolution
Coronal Imager (Hi-C) instrument hint that 0.3 arcsec resolution images
and &lt; 10 s cadence provide the necessary resolution to detect
heating events. Hi-C was launched from White Sands Missile Range on
July 11, 2012 (before the launch with IRIS) and obtained images of
a solar active region in the 19.3 nm passband. In this presentation,
I will discuss the potential of combining a flight in Hi-C with a 17.1
nm passband, in conjunction with IRIS. This combination will provide,
for the first time, a definitive method of tracing the energy flow
between the chromosphere and corona and vice versa.

---------------------------------------------------------
Title: An Airborne Infrared Spectrometer for Solar Eclipse
Observations
Authors: DeLuca, E.; Samra, J.; Golub, L.; Cheimets, P.
2016AGUFMSM51A2457D Altcode:
The airborne infrared spectrometer (AIR-Spec) is an innovative
solar spectrometer that will observe the 2017 solar eclipse from
the NSF/NCAR High-Performance Instrumented Airborne Platform for
Environmental Research (HIAPER). AIR-Spec will image five infrared
coronal emission lines to determine whether they may be useful probes
of coronal magnetism. AIR-Spec consists of an optical system (feed
telescope and a cooled grating spectrometer and infrared detector) and
an image stabilization system, which uses a fast steering mirror to
correct the line-of-sight for platform perturbations. To ensure that
the instrument meets its research goals, both systems are undergoing
extensive performance modeling and testing. We will present preliminary
results of November flight tests of the image stabilization systems,
a critical component of the program.

---------------------------------------------------------
Title: Solar Wind Electrons Alphas and Protons (SWEAP) Investigation:
Design of the Solar Wind and Coronal Plasma Instrument Suite for
Solar Probe Plus
Authors: Kasper, Justin C.; Abiad, Robert; Austin, Gerry;
Balat-Pichelin, Marianne; Bale, Stuart D.; Belcher, John W.; Berg,
Peter; Bergner, Henry; Berthomier, Matthieu; Bookbinder, Jay; Brodu,
Etienne; Caldwell, David; Case, Anthony W.; Chandran, Benjamin D. G.;
Cheimets, Peter; Cirtain, Jonathan W.; Cranmer, Steven R.; Curtis,
David W.; Daigneau, Peter; Dalton, Greg; Dasgupta, Brahmananda;
DeTomaso, David; Diaz-Aguado, Millan; Djordjevic, Blagoje; Donaskowski,
Bill; Effinger, Michael; Florinski, Vladimir; Fox, Nichola; Freeman,
Mark; Gallagher, Dennis; Gary, S. Peter; Gauron, Tom; Gates, Richard;
Goldstein, Melvin; Golub, Leon; Gordon, Dorothy A.; Gurnee, Reid; Guth,
Giora; Halekas, Jasper; Hatch, Ken; Heerikuisen, Jacob; Ho, George; Hu,
Qiang; Johnson, Greg; Jordan, Steven P.; Korreck, Kelly E.; Larson,
Davin; Lazarus, Alan J.; Li, Gang; Livi, Roberto; Ludlam, Michael;
Maksimovic, Milan; McFadden, James P.; Marchant, William; Maruca,
Bennet A.; McComas, David J.; Messina, Luciana; Mercer, Tony; Park,
Sang; Peddie, Andrew M.; Pogorelov, Nikolai; Reinhart, Matthew J.;
Richardson, John D.; Robinson, Miles; Rosen, Irene; Skoug, Ruth M.;
Slagle, Amanda; Steinberg, John T.; Stevens, Michael L.; Szabo, Adam;
Taylor, Ellen R.; Tiu, Chris; Turin, Paul; Velli, Marco; Webb, Gary;
Whittlesey, Phyllis; Wright, Ken; Wu, S. T.; Zank, Gary
2016SSRv..204..131K Altcode: 2015SSRv..tmp..119K
The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation
on Solar Probe Plus is a four sensor instrument suite that provides
complete measurements of the electrons and ionized helium and hydrogen
that constitute the bulk of solar wind and coronal plasma. SWEAP
consists of the Solar Probe Cup (SPC) and the Solar Probe Analyzers
(SPAN). SPC is a Faraday Cup that looks directly at the Sun and measures
ion and electron fluxes and flow angles as a function of energy. SPAN
consists of an ion and electron electrostatic analyzer (ESA) on
the ram side of SPP (SPAN-A) and an electron ESA on the anti-ram
side (SPAN-B). The SPAN-A ion ESA has a time of flight section that
enables it to sort particles by their mass/charge ratio, permitting
differentiation of ion species. SPAN-A and -B are rotated relative to
one another so their broad fields of view combine like the seams on a
baseball to view the entire sky except for the region obscured by the
heat shield and covered by SPC. Observations by SPC and SPAN produce
the combined field of view and measurement capabilities required to
fulfill the science objectives of SWEAP and Solar Probe Plus. SWEAP
measurements, in concert with magnetic and electric fields, energetic
particles, and white light contextual imaging will enable discovery
and understanding of solar wind acceleration and formation, coronal and
solar wind heating, and particle acceleration in the inner heliosphere
of the solar system. SPC and SPAN are managed by the SWEAP Electronics
Module (SWEM), which distributes power, formats onboard data products,
and serves as a single electrical interface to the spacecraft. SWEAP
data products include ion and electron velocity distribution functions
with high energy and angular resolution. Full resolution data are stored
within the SWEM, enabling high resolution observations of structures
such as shocks, reconnection events, and other transient structures
to be selected for download after the fact. This paper describes the
implementation of the SWEAP Investigation, the driving requirements
for the suite, expected performance of the instruments, and planned
data products, as of mission preliminary design review.

---------------------------------------------------------
Title: An airborne infrared spectrometer for solar eclipse
observations
Authors: Samra, Jenna; Cheimets, Peter; DeLuca, Edward; Galeros,
John; Gauron, Thomas; Golub, Leon; Guth, Giora; Hertz, Edward; Judge,
Philip; Koutchmy, Serge; Marquez, Vanessa
2016SPIE.9908E..5US Altcode:
This paper presents the design of an innovative solar spectrometer
that will y on the NSF/NCAR Gulfstream V High-Performance Instrumented
Airborne Platform for Environmental Research (GV HIAPER) during the
2017 solar eclipse. The airborne infrared spectrometer (AIR-Spec) is
groundbreaking in two aspects: it will image infrared coronal emission
lines that have never been measured, and it will bring high resolution
imaging to GV HIAPER. The instrument development faces the challenges
of achieving adequate resolution and signal-to-noise ratio in a compact
package mounted to a noisy moving platform. To ensure that AIR-Spec
meets its research goals, the instrument is undergoing pre-flight
modeling and testing. The results are presented with reference to the
instrument requirements.

---------------------------------------------------------
Title: An Airborne Infrared Spectrometer for Solar Eclipse
Observations
Authors: Samra, Jenna; DeLuca, Edward; Golub, Leon; Cheimets, Peter;
Judge, Philip
2016shin.confE.155S Altcode:
The airborne infrared spectrometer (AIR-Spec) is an innovative
solar spectrometer that will observe the 2017 solar eclipse from
the NSF/NCAR High-Performance Instrumented Airborne Platform for
Environmental Research (HIAPER). AIR-Spec will image five infrared
coronal emission lines to determine whether they may be useful probes
of coronal magnetism. The solar magnetic field provides the free
energy that controls coronal heating, structure, and dynamics. Energy
stored in coronal magnetic fields is released in flares and coronal mass
ejections and ultimately drives space weather. Therefore, direct coronal
field measurements have significant potential to enhance understanding
of coronal dynamics and improve solar forecasting models. Of particular
interest are observations of field lines in the transitional region
between closed and open flux systems, providing important information
on the origin of the slow solar wind. While current instruments
routinely observe only the photospheric and chromospheric magnetic
fields, AIR-Spec will take a step toward the direct observation of
coronal fields by measuring plasma emission in the infrared at high
spatial and spectral resolution. During the total solar eclipse of
2017, AIR-Spec will search for five magnetically sensitive coronal
emission lines between 1.4 and 4 μm from the HIAPER Gulfstream V at
an altitude above 14.9 km. The instrument will measure emission line
intensity, width, and Doppler shift, map the spatial distribution of
infrared emitting plasma, and search for waves in the emission line
velocities. AIR-Spec consists of an optical system (feed telescope,
grating spectrometer, and infrared detector) and an image stabilization
system, which uses a fast steering mirror to correct the line-of-sight
for platform perturbations. To ensure that the instrument meets its
research goals, both systems are undergoing extensive performance
modeling and testing. These results are shown with reference to the
science requirements.

---------------------------------------------------------
Title: On the alignment and focusing of the Marshall Grazing Incidence
X-ray Spectrometer (MaGIXS)
Authors: Champey, Patrick; Winebarger, Amy; Kobayashi, Ken; Savage,
Sabrina; Cirtain, Jonathan; Cheimets, Peter; Hertz, Edward; Golub,
Leon; Ramsey, Brian; McCracken, Jeff; Marquez, Vanessa; Allured,
Ryan; Heilmann, Ralf K.; Schattenburg, Mark; Bruccoleri, Alexander
2016SPIE.9905E..73C Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA
sounding rocket instrument that is designed to observe soft X-ray
emissions from 24 - 6.0 Å (0.5 - 2.0 keV energies) in the solar
atmosphere. For the first time, high-temperature, low-emission plasma
will be observed directly with 5 arcsecond spatial resolution and
22 mÅ spectral resolution. The unique optical design consists of a
Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The
spectrometer utilizes a finite conjugate mirror pair and a blazed
planar, varied line spaced grating, which is directly printed on
a silicon substrate using e-beam lithography. The grating design is
being finalized and the grating will be fabricated by the Massachusetts
Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight
Center (MSFC) is producing the nickel replicated telescope and
spectrometer mirrors using the same facilities and techniques as
those developed for the ART-XC and FOXSI mirrors. The Smithsonian
Astrophysical Observatory (SAO) will mount and align the optical
sub-assemblies based on previous experience with similar instruments,
such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer
assembly will be aligned in visible light through the implementation
of a theodolite and reference mirrors, in addition to the centroid
detector assembly (CDA) - a device designed to align the AXAF-I nested
mirrors. Focusing of the telescope and spectrometer will be achieved
using the X-ray source in the Stray Light Facility (SLF) at MSFC. We
present results from an alignment sensitivity analysis performed on
the on the system and we also discuss the method for aligning and
focusing MaGIXS.

---------------------------------------------------------
Title: An Airborne Infrared Spectrometer for Solar Eclipse
Observations
Authors: Samra, Jenna; DeLuca, Edward E.; Golub, Leon; Cheimets,
Peter; Philip, Judge
2016SPD....4730106S Altcode:
The airborne infrared spectrometer (AIR-Spec) is an innovative
solar spectrometer that will observe the 2017 solar eclipse from
the NSF/NCAR High-Performance Instrumented Airborne Platform for
Environmental Research (HIAPER). AIR-Spec will image five infrared
coronal emission lines to determine whether they may be useful probes
of coronal magnetism.The solar magnetic field provides the free energy
that controls coronal heating, structure, and dynamics. Energy stored in
coronal magnetic fields is released in flares and coronal mass ejections
and ultimately drives space weather. Therefore, direct coronal field
measurements have significant potential to enhance understanding of
coronal dynamics and improve solar forecasting models. Of particular
interest are observations of field lines in the transitional region
between closed and open flux systems, providing important information on
the origin of the slow solar wind.While current instruments routinely
observe only the photospheric and chromospheric magnetic fields,
AIR-Spec will take a step toward the direct observation of coronal
fields by measuring plasma emission in the infrared at high spatial and
spectral resolution. During the total solar eclipse of 2017, AIR-Spec
will observe five magnetically sensitive coronal emission lines between
1.4 and 4 µm from the HIAPER Gulfstream V at an altitude above 14.9
km. The instrument will measure emission line intensity, width, and
Doppler shift, map the spatial distribution of infrared emitting plasma,
and search for waves in the emission line velocities.AIR-Spec consists
of an optical system (feed telescope, grating spectrometer, and infrared
detector) and an image stabilization system, which uses a fast steering
mirror to correct the line-of-sight for platform perturbations. To
ensure that the instrument meets its research goals, both systems are
undergoing extensive performance modeling and testing. These results
are shown with reference to the science requirements.

---------------------------------------------------------
Title: A Wide-Field Coronal EUV Imager for the ISS
Authors: Golub, Leon; Savage, Sabrina
2016SPD....47.0805G Altcode:
We propose a novel dual-usage EUV imager designed to observe the solar
corona from the solar surface out to ~3 R_sol, with the objectives of:
1. determining the dynamics of the Transition Corona, the region in
which the corona changes from low-beta and dominated by magnetically
confined closed structures to high beta and having generally open
regions with outflowing solar wind streams and mostly radial streamer
structures; 2. providing new tools for space weather forecasting
via early detection of a coronal mass ejection (CME) eruption, early
acceleration and path detection, and modelling of the CME magnetic
structure and configuration at launch. The latter goal will be achieved
in combination with ground-based measurements. A mechanism switches the
observing mode to spectroscopic imaging with the goal of understanding
the dynamics of CMEs and of high-temperature plasma above and around
active regions. The instrument is intended to mount to the ISS, tracking
the Sun continuously during its daylight passes, and will be proposed
as a Mission of Opportunity within the SMEX program.

---------------------------------------------------------
Title: Is it Possible to Use the Green Coronal Line Instead of X rays
to Cancel an Effect of the Coronal Emissivity Deficit in Estimation of
the Prominence Total Mass from Decrease of the EUV-corona Intensities?
Authors: Schwartz, P.; Heinzel, P.; Jejčič, S.; Rybák, J.; Kotrč,
P.; Fárník, F.; Kupryakov, Yu. A.; Deluca, E. E.; Golub, L.; Jibben,
P. R.; Anzer, U.; Tlatov, A. G. .; Guseva, S. A.
2016ASPC..504...89S Altcode:
Total masses of six quiescent prominences observed from April through
June 2011 were estimated using multi-spectral observations (in EUV,
X-rays, Hα, and Ca &lt;small&gt;II&lt;/small&gt; H). The method for
the total mass estimation is based on the fact that the intensity
of the EUV solar corona at wavelengths below 912 Å is reduced at a
prominence by the absorption in resonance continua (photoionisation)
of hydrogen and possibly by helium and subsequently an amount of
absorbed radiation is proportional to the column density of hydrogen
and helium plasma. Moreover, the deficit of the coronal emissivity in
volume occupied by the cool prominence plasma also contributes to the
intensity decrease. The observations in X-rays which are not absorbed
by the prominence plasma, allow us to separate these two mechanisms
from each other. The X-ray observations of XRT onboard the Hinode
satellite made with the Al-mesh focal filter were used because the
X-ray coronal radiation formed in plasma of temperatures of the order
of 106 K was registered and EUV spectral lines occurring in
the 193, 211 and 335 Å channels of the Atmospheric Imaging Assembly
of the Solar Dynamics Observatory satellite are also formed at such
temperatures. Unfortunately, the Al-mesh filter has a secondary peak
of the transmittance at around 171 Å which causes a contribution
from the EUV corona to the measured data of up to 11 % in the quiet
corona. Thus, absorption in prominence plasma influences XRT X-ray
data when using the Al-mesh filter. On the other hand, other X-ray XRT
filters are more sensitive to plasma of much higher temperatures (log
T of the order of 7), thus observations using these filters cannot
be used together with the AIA observations in the method for mass
estimations. This problem could be solved using observations in the
green coronal line instead of X-rays. Absorption of the green coronal
line by a prominence plasma is negligible and this line is formed at
temperatures of the order of 106 K. We compare values of
the total mass of the prominence observed on 20 October 2012 on the
SE limb estimated when using XRT X-ray observations and observations
in the green coronal line obtained at Kislovodsk Mountain Astronomical
Station of the Pulkovo observatory (Russia).

---------------------------------------------------------
Title: Low-density laboratory spectra near the He II λ304 line
Authors: Träbert, Elmar; Beiersdorfer, Peter; Brickhouse, Nancy S.;
Golub, Leon
2016A&A...586A.115T Altcode:
 Aims: To interpret the EUV spectra of the solar corona, one
hopes for laboratory data of specific chemical elements obtained under
coronal conditions. Methods: EUV spectra of He, C, N, O, F,
Ne, S, Ar, Fe, and Ni in a 40 Å wide wavelength interval near λ304
were excited in an electron beam ion trap. Results: We observe
some two hundred lines about half of which are not yet identified and
included in spectral models. Conclusions: Our data provide a
check on the atomic data bases underlying the spectral models that are
used to interpret solar corona data. However, a multitude of mostly weak
additional lines taken together represent a flux that is comparable to
that of various primary lines. Research supported by the Solar
and Heliospherical Physics Program of the National Aeronautics and
Space Administration under award NNH10AN31I.

---------------------------------------------------------
Title: Simultaneous IRIS and Hinode/EIS Observations and Modelling
of the 2014 October 27 X2.0 Class Flare
Authors: Polito, V.; Reep, J. W.; Reeves, K. K.; Simões, P. J. A.;
Dudík, J.; Del Zanna, G.; Mason, H. E.; Golub, L.
2016ApJ...816...89P Altcode: 2015arXiv151206378P
We present a study of the X2-class flare which occurred on 2014 October
27 and was observed with the Interface Region Imaging Spectrograph
(IRIS) and the EUV Imaging Spectrometer (EIS) on board the Hinode
satellite. Thanks to the high cadence and spatial resolution of the IRIS
and EIS instruments, we are able to compare simultaneous observations
of the Fe xxi 1354.08 Å and Fe xxiii 263.77 Å high-temperature
emission (≳10 MK) in the flare ribbon during the chromospheric
evaporation phase. We find that IRIS observes completely blueshifted
Fe xxi line profiles, up to 200 km s-1 during the rise
phase of the flare, indicating that the site of the plasma upflows is
resolved by IRIS. In contrast, the Fe xxiii line is often asymmetric,
which we interpret as being due to the lower spatial resolution of
EIS. Temperature estimates from SDO/AIA and Hinode/XRT show that hot
emission (log(T[K]) &gt; 7.2) is first concentrated at the footpoints
before filling the loops. Density-sensitive lines from IRIS and
EIS give estimates of electron number density of ≳1012
cm-3 in the transition region lines and 1010
cm-3 in the coronal lines during the impulsive phase. In
order to compare the observational results against theoretical
predictions, we have run a simulation of a flare loop undergoing
heating using the HYDRAD 1D hydro code. We find that the simulated
plasma parameters are close to the observed values that are obtained
with IRIS, Hinode, and AIA. These results support an electron beam
heating model rather than a purely thermal conduction model as the
driving mechanism for this flare.

---------------------------------------------------------
Title: Airborne Infrared Spectrograph for Eclipse Observations
Authors: Golub, L.; Cheimets, P.; DeLuca, E. E.; Samra, J.; Judge,
P. G.
2015AGUFMSH51C2454G Altcode:
Direct measurements of the coronal magnetic field have significant
potential to enhance our understanding of coronal dynamics, and improve
forecasting models. Of particular interest are observations of coronal
field lines in the Transition Corona, the transitional region between
closed and open flux systems, providing important information on
eruptive instabilities and on the origin of the slow solar wind. While
current instruments routinely observe the photospheric and chromospheric
magnetic fields, the proposed airborne spectrometer will take a step
toward the direct observation of coronal fields by measuring plasma
emission in the infrared at high spatial and spectral resolution. The
targeted lines are five forbidden magnetic dipole transitions between
1.4 and 4 um. The airborne system will consist of a telescope,
grating spectrometer and pointing/stabilization system to be flown
on the NSF/NCAR High-performance Instrumented Airborne Platform for
Environmental Research (HIAPER) during the 21 August 2017 total solar
eclipse. We will discuss the scientific objectives of the 2017 flight,
describe details of the instrument design, and present the observing
program for the eclipse.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Champey, P. R.; Winebarger, A. R.; Kobayashi, K.; Savage,
S. L.; Cirtain, J. W.; Cheimets, P.; Hertz, E.; Golub, L.; Ramsey,
B.; McCracken, J.; Heilmann, R.; Schattenburg, M.; Bruccoleri, A.
2015AGUFMSH43B2458C Altcode:
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA
soundingrocket instrument designed to observe soft X-ray emissions at
0.5 - 2.0 keV energies in thesolar atmosphere. The primary science
goal is to differentiate steady, low-frequency heatingevents from
sporadic, high-frequency heating events in the active region core For
the first time, high-temperature, low-emission plasma will be observed
directly with 5 arcsec spatialand 22 mÅ spectral resolution. The
novel optical design consists of a Wolter I telescope anda 3-optic
grazing-incidence spectrograph. The X-ray spectrograph utilizes a finite
conjugatemirror pair and a planar, nanoprinted-silicon varied line
space grating, which is being devel-oped by the Massachusetts Institute
of Technology (MIT). The telescope and spectrographmirrors will be
nickel replicated and coated with iridium. Mandrel fabrication and
nickelreplication will be done at MSFC as part of its replicated X-ray
optics program. Mounting,alignment, and integration of the ight optics
will be performed at the Harvard-SmithsonianCenter for Astrophysics
(SAO). The MaGIXS science camera is being developed at MSFCand is based
on CLASP heritage, which obtained read noise performance of 5.5 e?-
RMS. Thecamera will include a e2v Technologies 2kx2k frame transfer
CCD with 4-channel readout(500 kpixel/s/channel). We will present an
overview of the MaGIXS optical system andfabrication of the telescope
and spectrograph mirrors.

---------------------------------------------------------
Title: Limb Event Brightenings and Fast Ejection Using IRIS Mission
Observations
Authors: Tavabi, E.; Koutchmy, S.; Golub, L.
2015SoPh..290.2871T Altcode: 2015SoPh..tmp..118T; 2015arXiv150706794T
The Interface Region Imaging Spectrograph (IRIS) of the recently
commissioned NASA small explorer mission provides significantly more
complete and higher resolution spectral coverage of the dynamical
conditions inside the chromosphere and transition region (TR) than has
been available ever before. High temporal, spatial (0.3″)
and spectral resolution observations from the ultraviolet IRIS spectra
near the solar limb reveal high-energy limb event brightenings (LEBs)
at low chromospheric heights at about 1 Mm above the limb. They can be
characterized as explosive events producing jets. We selected two events
showing spectra of a confined eruption just off or near the quiet-Sun
limb, the jet part showing obvious moving material with short-duration
large Doppler shifts in three directions that were identified as
macrospicules on slit-jaw (SJ) images in Si IV and He II 304 Å. The
events were analyzed from a sequence of very close rasters taken near
the central meridian and the South Pole limb. We analyzed the processed
SJ images and the simultaneously observed fast spectral sequences, which
have large Doppler shifts, with a pair of redshifted elements together
with a faster blueshifted element from almost the same position. Shifts
correspond to velocities of up to 100 kms−1 in projection
on the plane of the sky. Erupting spicules and macrospicules from these
regions are visible in images taken before and after the spectra. The
cool low first ionization potential (FIP) element simultaneous line
emissions of the Mg II h and k resonance lines do not clearly show a
similar signature because of optical thickness effects, but the Si IV
broadband SJ images do. The bidirectional plasma jets ejected from a
small reconnection site are interpreted to be the result of coronal
loop-loop interactions that lead to reconnection in nearby sites.

---------------------------------------------------------
Title: Book review: Nearest Star: The surprising science of our Sun
(Golub &amp; Pasachoff)
Authors: Smith, L.; Golub, L.; Pasachoff, J. M.
2015JBAA..125..183S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Joint High Temperature Observation of a Small C6.5 Solar
Flare With Iris/Eis/Aia
Authors: Polito, V.; Reeves, K. K.; Del Zanna, G.; Golub, L.; Mason,
H. E.
2015ApJ...803...84P Altcode:
We present the observation of a C6.5 class flare on 2014 February 3,
obtained with the Interface Region Imaging Spectrograph (IRIS) and
the EUV Imaging Spectrometer (EIS) on board HINODE. We follow the
details of the impulsive phase with IRIS and the gradual decay phase
with both IRIS and EIS. The IRIS Slit-Jaw Imager and Atmospheric
Imaging Assembly (AIA) are used to precisely co-align the two sets
of spectroscopic observations. Of particular interest is the Fe xxi
1354.08 Å spectral line, which is the highest temperature emission
(∼10 MK) observed in the IRIS wavelength range. We show the evolution
of the Fe xxi profiles during the impulsive phase of the flare at the
same ribbon location with a 75 s temporal cadence. Totally blueshifted
(∼82 km {{s}-1}) profiles are found at the very early
phase of the flare and gradually decrease in about 6 minutes. This
result is consistent with 1D model predictions during chromospheric
evaporation in flares. The blueshifted components also exhibit large
non-thermal broadening, which decreases simultaneously with the
blueshifted velocity. After the evaporation first occurs, the Fe xxi
intensity progressively moves from the footpoints to the top of the
hot flare loops seen in the AIA 131 Å images, where the emission is
observed to be at rest and thermal. Emission measure estimates from
IRIS/EIS/AIA observations during the gradual phase show isothermal loop
top structures cooling from about 13.5 to 12 MK with electron densities
of the order of ∼ 5-6× {{10}10} c{{m}-3}.

---------------------------------------------------------
Title: Internetwork Chromospheric Bright Grains Observed With IRIS
and SST
Authors: Martínez-Sykora, Juan; Rouppe van der Voort, Luc; Carlsson,
Mats; De Pontieu, Bart; Pereira, Tiago M. D.; Boerner, Paul; Hurlburt,
Neal; Kleint, Lucia; Lemen, James; Tarbell, Ted D.; Title, Alan;
Wuelser, Jean-Pierre; Hansteen, Viggo H.; Golub, Leon; McKillop, Sean;
Reeves, Kathy K.; Saar, Steven; Testa, Paola; Tian, Hui; Jaeggli,
Sarah; Kankelborg, Charles
2015ApJ...803...44M Altcode: 2015arXiv150203490M
The Interface Region Imaging Spectrograph (IRIS) reveals small-scale
rapid brightenings in the form of bright grains all over coronal holes
and the quiet Sun. These bright grains are seen with the IRIS 1330,
1400, and 2796 Å slit-jaw filters. We combine coordinated observations
with IRIS and from the ground with the Swedish 1 m Solar Telescope
(SST) which allows us to have chromospheric (Ca ii 8542 Å, Ca ii H
3968 Å, Hα, and Mg ii k 2796 Å) and transition region (C ii 1334 Å,
Si iv 1403 Å) spectral imaging, and single-wavelength Stokes maps
in Fe i 6302 Å at high spatial (0\buildrel{\prime\prime}\over{.}
33), temporal, and spectral resolution. We conclude that the IRIS
slit-jaw grains are the counterpart of so-called acoustic grains,
i.e., resulting from chromospheric acoustic waves in a non-magnetic
environment. We compare slit-jaw images (SJIs) with spectra from the
IRIS spectrograph. We conclude that the grain intensity in the 2796
Å slit-jaw filter comes from both the Mg ii k core and wings. The
signal in the C ii and Si iv lines is too weak to explain the presence
of grains in the 1300 and 1400 Å SJIs and we conclude that the grain
signal in these passbands comes mostly from the continuum. Although
weak, the characteristic shock signatures of acoustic grains can often
be detected in IRIS C ii spectra. For some grains, a spectral signature
can be found in IRIS Si iv. This suggests that upward propagating
acoustic waves sometimes reach all the way up to the transition region.

---------------------------------------------------------
Title: Homologous Helical Jets: Observations By IRIS, SDO, and Hinode
and Magnetic Modeling With Data-Driven Simulations
Authors: Cheung, Mark C. M.; De Pontieu, B.; Tarbell, T. D.; Fu, Y.;
Tian, H.; Testa, P.; Reeves, K. K.; Martínez-Sykora, J.; Boerner,
P.; Wülser, J. P.; Lemen, J.; Title, A. M.; Hurlburt, N.; Kleint,
L.; Kankelborg, C.; Jaeggli, S.; Golub, L.; McKillop, S.; Saar, S.;
Carlsson, M.; Hansteen, V.
2015ApJ...801...83C Altcode: 2015arXiv150101593C
We report on observations of recurrent jets by instruments on board
the Interface Region Imaging Spectrograph, Solar Dynamics Observatory
(SDO), and Hinode spacecraft. Over a 4 hr period on 2013 July 21,
recurrent coronal jets were observed to emanate from NOAA Active Region
11793. Far-ultraviolet spectra probing plasma at transition region
temperatures show evidence of oppositely directed flows with components
reaching Doppler velocities of ±100 km s-1. Raster Doppler
maps using a Si iv transition region line show all four jets to have
helical motion of the same sense. Simultaneous observations of the
region by SDO and Hinode show that the jets emanate from a source
region comprising a pore embedded in the interior of a supergranule. The
parasitic pore has opposite polarity flux compared to the surrounding
network field. This leads to a spine-fan magnetic topology in the
coronal field that is amenable to jet formation. Time-dependent
data-driven simulations are used to investigate the underlying drivers
for the jets. These numerical experiments show that the emergence of
current-carrying magnetic field in the vicinity of the pore supplies
the magnetic twist needed for recurrent helical jet formation.

---------------------------------------------------------
Title: Total mass of six quiescent prominences estimated from their
multi-spectral observations
Authors: Schwartz, P.; Heinzel, P.; Kotrč, P.; Fárník, F.;
Kupryakov, Yu. A.; DeLuca, E. E.; Golub, L.
2015A&A...574A..62S Altcode:
Context. Total masses of six solar prominences were estimated using
prominence multi-spectral observations (in EUV, X-rays, Hα, and Ca
ii H). The observations were made during the observing campaign from
April through June 2011. Aims: The aim of the work was to apply
a complex method for the prominence mass estimations that can be used
later for other prominences observed during the observing campaign. Methods: Our method is based on the fact that intensity of the EUV
solar corona at wavelengths below 912 Å is reduced by the absorption
in resonance continua of hydrogen and helium (photoionisation) and at
the same time also by a deficit of the coronal emissivity in volume
occupied by the cool prominence plasma. Both mechanisms contribute to
intensity decrease simultaneously. The observations in X-rays allow us
to separate these mechanisms from each other. Coronal emission behind a
prominence is not estimated by any temporal or spatial interpolation,
but by using a new method based on comparing the ratio of the optical
thickness at 193 Å and 211 Å determined from the observations
with the theoretical ratio. Results: Values of the total mass
estimated for six prominences are between 2.9 × 1011 and
1.7 × 1012 kg. The column density of hydrogen is of the
order of 1018-1019 cm-2. Our results
agree with results of other authors. Conclusions: The method
is now ready to be used for all 30 prominences observed during the
campaign. Then in the near future it will be possible to obtain a
statistics of the total mass of quiescent solar prominences.

---------------------------------------------------------
Title: Filling the Gap: Viewing the Corona from the Disk to the
Source Surface
Authors: Golub, L.
2014AGUFMSH52B..05G Altcode:
Only recently has it become clear that the solar corona viewed in
the EUV is detected out to far greater distances above the limb than
had been expected (Seaton etal 2013). The reasons for the visibility
of streamers out to &gt;2 R_sol are unclear (Goaryaev etal 2014),
but the fact that such structures can be seen is indisputable (Masson
etal 2014). The EUV imaging instruments that have been used for these
observations, such as TRACE, SWAP, STEREO and AIA, were not specifically
designed to detect the extended corona, and such detection typically
requires multiple exposures and mosaics. An instrument designed to
obtain views of the extended EUV corona out to the nominal source
surface with high efficiency is straightforward to build, and would
provide 100X to 1000X higher sensitivity than current instruments. The
main advantages of such EUV observations are: 1. the coronal dynamics
and eruptions (such as CMEs) and the locations and effects of nearby
streamers are visible from the start of the event on-disk; 2. the
initial conditions of an event, including initial acceleration,
changes of path due to interaction with nearby coronal structures, and
propagation of coronal waves from the eruption site, are all directly
seen; 3. the evolution of the eruption from the solar surface out to
the inner edge of a white-light coronagraph can be seen, thus filling
the gap in such WL images (Byrne etal 2014). We will present a class of
simple EUV wide-field imager designs for implementation on a low-cost
platform. Operation in the EUV implies that Sun-centered pointing
tolerances can be relaxed, dust and scattering are negligible issues,
and simple optics will fulfill all requirements. Implementation on a
Sun-pointed spinning spacecraft is possible without great difficulty.

---------------------------------------------------------
Title: Toward the Direct Measurement of Coronal Magnetic Fields:
An Airborne Infrared Spectrometer for Eclipse Observations
Authors: Samra, J.; DeLuca, E. E.; Golub, L.; Cheimets, P.
2014AGUFMSH53B4214S Altcode:
The solar magnetic field enables the heating of the corona and
provides its underlying structure. Energy stored in coronal magnetic
fields is released in flares and coronal mass ejections (CME) and
provides the ultimate source of energy for space weather. Therefore,
direct measurements of the coronal magnetic field have significant
potential to enhance understanding of coronal dynamics and improve
solar forecasting models. Of particular interest are observations
of coronal field lines in the transitional region between closed and
open flux systems, providing important information on the origin of
the slow solar wind. While current instruments routinely observe only
the photospheric and chromospheric magnetic fields, a proposed airborne
spectrometer will take a step toward the direct observation of coronal
fields by measuring plasma emission in the infrared at high spatial
and spectral resolution. The targeted lines are four forbidden magnetic
dipole transitions between 2 and 4 μm. The airborne system will consist
of a telescope, grating spectrometer, and pointing/stabilization
system to be flown on the NSF/NCAR High-performance Instrumented
Airborne Platform for Environmental Research (HIAPER) during the
August 2017 total solar eclipse. The project incorporates several
optical engineering challenges, centered around maintaining adequate
spectral and spatial resolution in a compact and inexpensive package
and on a moving platform. Design studies are currently underway to
examine the tradeoffs between various optical geometries and control
strategies for the pointing/stabilization system. The results will
be presented and interpreted in terms of the consequences for the
scientific questions. In addition, results from a laboratory prototype
and simulations of the final system will be presented.

---------------------------------------------------------
Title: The High-Resolution Coronal Imager (Hi-C)
Authors: Kobayashi, Ken; Cirtain, Jonathan; Winebarger, Amy R.;
Korreck, Kelly; Golub, Leon; Walsh, Robert W.; De Pontieu, Bart;
DeForest, Craig; Title, Alan; Kuzin, Sergey; Savage, Sabrina; Beabout,
Dyana; Beabout, Brent; Podgorski, William; Caldwell, David; McCracken,
Kenneth; Ordway, Mark; Bergner, Henry; Gates, Richard; McKillop,
Sean; Cheimets, Peter; Platt, Simon; Mitchell, Nick; Windt, David
2014SoPh..289.4393K Altcode: 2014SoPh..tmp..104K
The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding
rocket on 11 July 2012. The goal of the Hi-C mission was to obtain
high-resolution (≈ 0.3 - 0.4”), high-cadence (≈ 5 seconds)
images of a solar active region to investigate the dynamics of solar
coronal structures at small spatial scales. The instrument consists of
a normal-incidence telescope with the optics coated with multilayers
to reflect a narrow wavelength range around 19.3 nm (including the
Fe XII 19.5-nm spectral line) and a 4096×4096 camera with a plate
scale of 0.1” pixel−1. The target of the Hi-C rocket
flight was Active Region 11520. Hi-C obtained 37 full-frame images
and 86 partial-frame images during the rocket flight. Analysis of the
Hi-C data indicates the corona is structured on scales smaller than
currently resolved by existing satellite missions.

---------------------------------------------------------
Title: High-resolution Laboratory Spectra of the λ193 Channel of
the Atmospheric Imaging Assembly Instrument on Board Solar Dynamics
Observatory
Authors: Träbert, Elmar; Beiersdorfer, Peter; Brickhouse, Nancy S.;
Golub, Leon
2014ApJS..215....6T Altcode:
Extreme ultraviolet spectra of C, O, F, Ne, S, Ar, Fe, and Ni have
been excited in an electron beam ion trap and studied with much higher
resolution than available on the Solar Dynamics Observatory (SDO)
in order to ascertain the spectral composition of the SDO/Atmospheric
Imaging Assembly (AIA) observations. We present our findings in the
wavelength range 182-200 Å, which, overall, corroborate the working
models of how to interpret the SDO/AIA data. We find, however, that
the inclusion of a number of additional lines might improve the data
interpretation.

---------------------------------------------------------
Title: Hot explosions in the cool atmosphere of the Sun
Authors: Peter, H.; Tian, H.; Curdt, W.; Schmit, D.; Innes, D.;
De Pontieu, B.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt, N.;
Tarbell, T. D.; Wuelser, J. P.; Martínez-Sykora, Juan; Kleint,
L.; Golub, L.; McKillop, S.; Reeves, K. K.; Saar, S.; Testa, P.;
Kankelborg, C.; Jaeggli, S.; Carlsson, M.; Hansteen, V.
2014Sci...346C.315P Altcode: 2014arXiv1410.5842P
The solar atmosphere was traditionally represented with a simple
one-dimensional model. Over the past few decades, this paradigm shifted
for the chromosphere and corona that constitute the outer atmosphere,
which is now considered a dynamic structured envelope. Recent
observations by the Interface Region Imaging Spectrograph (IRIS) reveal
that it is difficult to determine what is up and down, even in the cool
6000-kelvin photosphere just above the solar surface: This region hosts
pockets of hot plasma transiently heated to almost 100,000 kelvin. The
energy to heat and accelerate the plasma requires a considerable
fraction of the energy from flares, the largest solar disruptions. These
IRIS observations not only confirm that the photosphere is more complex
than conventionally thought, but also provide insight into the energy
conversion in the process of magnetic reconnection.

---------------------------------------------------------
Title: The unresolved fine structure resolved: IRIS observations of
the solar transition region
Authors: Hansteen, V.; De Pontieu, B.; Carlsson, M.; Lemen, J.; Title,
A.; Boerner, P.; Hurlburt, N.; Tarbell, T. D.; Wuelser, J. P.; Pereira,
T. M. D.; De Luca, E. E.; Golub, L.; McKillop, S.; Reeves, K.; Saar,
S.; Testa, P.; Tian, H.; Kankelborg, C.; Jaeggli, S.; Kleint, L.;
Martínez-Sykora, J.
2014Sci...346E.315H Altcode: 2014arXiv1412.3611H
The heating of the outer solar atmospheric layers, i.e., the transition
region and corona, to high temperatures is a long-standing problem
in solar (and stellar) physics. Solutions have been hampered by an
incomplete understanding of the magnetically controlled structure of
these regions. The high spatial and temporal resolution observations
with the Interface Region Imaging Spectrograph (IRIS) at the solar
limb reveal a plethora of short, low-lying loops or loop segments
at transition-region temperatures that vary rapidly, on the time
scales of minutes. We argue that the existence of these loops solves
a long-standing observational mystery. At the same time, based on
comparison with numerical models, this detection sheds light on a
critical piece of the coronal heating puzzle.

---------------------------------------------------------
Title: Evidence of nonthermal particles in coronal loops heated
impulsively by nanoflares
Authors: Testa, P.; De Pontieu, B.; Allred, J.; Carlsson, M.; Reale,
F.; Daw, A.; Hansteen, V.; Martinez-Sykora, J.; Liu, W.; DeLuca, E. E.;
Golub, L.; McKillop, S.; Reeves, K.; Saar, S.; Tian, H.; Lemen, J.;
Title, A.; Boerner, P.; Hurlburt, N.; Tarbell, T. D.; Wuelser, J. P.;
Kleint, L.; Kankelborg, C.; Jaeggli, S.
2014Sci...346B.315T Altcode: 2014arXiv1410.6130T
The physical processes causing energy exchange between the Sun’s
hot corona and its cool lower atmosphere remain poorly understood. The
chromosphere and transition region (TR) form an interface region between
the surface and the corona that is highly sensitive to the coronal
heating mechanism. High-resolution observations with the Interface
Region Imaging Spectrograph (IRIS) reveal rapid variability (~20 to
60 seconds) of intensity and velocity on small spatial scales (≲500
kilometers) at the footpoints of hot and dynamic coronal loops. The
observations are consistent with numerical simulations of heating by
beams of nonthermal electrons, which are generated in small impulsive
(≲30 seconds) heating events called “coronal nanoflares.” The
accelerated electrons deposit a sizable fraction of their energy
(≲1025 erg) in the chromosphere and TR. Our analysis
provides tight constraints on the properties of such electron beams
and new diagnostics for their presence in the nonflaring corona.

---------------------------------------------------------
Title: Prevalence of small-scale jets from the networks of the solar
transition region and chromosphere
Authors: Tian, H.; DeLuca, E. E.; Cranmer, S. R.; De Pontieu, B.;
Peter, H.; Martínez-Sykora, J.; Golub, L.; McKillop, S.; Reeves,
K. K.; Miralles, M. P.; McCauley, P.; Saar, S.; Testa, P.; Weber,
M.; Murphy, N.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt, N.;
Tarbell, T. D.; Wuelser, J. P.; Kleint, L.; Kankelborg, C.; Jaeggli,
S.; Carlsson, M.; Hansteen, V.; McIntosh, S. W.
2014Sci...346A.315T Altcode: 2014arXiv1410.6143T
As the interface between the Sun’s photosphere and corona, the
chromosphere and transition region play a key role in the formation and
acceleration of the solar wind. Observations from the Interface Region
Imaging Spectrograph reveal the prevalence of intermittent small-scale
jets with speeds of 80 to 250 kilometers per second from the narrow
bright network lanes of this interface region. These jets have lifetimes
of 20 to 80 seconds and widths of ≤300 kilometers. They originate from
small-scale bright regions, often preceded by footpoint brightenings
and accompanied by transverse waves with amplitudes of ~20 kilometers
per second. Many jets reach temperatures of at least ~105
kelvin and constitute an important element of the transition region
structures. They are likely an intermittent but persistent source of
mass and energy for the solar wind.

---------------------------------------------------------
Title: On the prevalence of small-scale twist in the solar
chromosphere and transition region
Authors: De Pontieu, B.; Rouppe van der Voort, L.; McIntosh, S. W.;
Pereira, T. M. D.; Carlsson, M.; Hansteen, V.; Skogsrud, H.; Lemen,
J.; Title, A.; Boerner, P.; Hurlburt, N.; Tarbell, T. D.; Wuelser,
J. P.; De Luca, E. E.; Golub, L.; McKillop, S.; Reeves, K.; Saar,
S.; Testa, P.; Tian, H.; Kankelborg, C.; Jaeggli, S.; Kleint, L.;
Martinez-Sykora, J.
2014Sci...346D.315D Altcode: 2014arXiv1410.6862D
The solar chromosphere and transition region (TR) form an interface
between the Sun’s surface and its hot outer atmosphere. There,
most of the nonthermal energy that powers the solar atmosphere
is transformed into heat, although the detailed mechanism remains
elusive. High-resolution (0.33-arc second) observations with NASA’s
Interface Region Imaging Spectrograph (IRIS) reveal a chromosphere
and TR that are replete with twist or torsional motions on sub-arc
second scales, occurring in active regions, quiet Sun regions, and
coronal holes alike. We coordinated observations with the Swedish
1-meter Solar Telescope (SST) to quantify these twisting motions and
their association with rapid heating to at least TR temperatures. This
view of the interface region provides insight into what heats the low
solar atmosphere.

---------------------------------------------------------
Title: Open questions on prominences from coordinated observations
by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP
Authors: Schmieder, B.; Tian, H.; Kucera, T.; López Ariste, A.;
Mein, N.; Mein, P.; Dalmasse, K.; Golub, L.
2014A&A...569A..85S Altcode: 2014arXiv1407.3171S
Context. A large prominence was observed by multiple instruments on the
ground and in space during an international campaign on September 24,
2013, for three hours (12:12 UT -15:12 UT). Instruments used in the
campaign included the newly launched (June 2013) Interface Region
Imaging Spectrograph (IRIS), THEMIS (Tenerife), the Hinode Solar
Optical Telescope (SOT), the Solar Dynamic Observatory's Atmospheric
Imaging Assembly (SDO/AIA), and the Multichannel Subtractive Double
Pass spectrograph (MSDP) in the Meudon Solar Tower. The movies obtained
in 304 Å with the EUV imager SDO/AIA, and in Ca II line by SOT show
the dynamic nature of the prominence. Aims: The aim of this
work is to study the dynamics of the prominence fine structures in
multiple wavelengths to understand their formation. Methods:
The spectrographs IRIS and MSDP provided line profiles with a high
cadence in Mg II h (2803.5 Å) and k (2796.4 Å) lines along four
slit positions (IRIS), and in Hα in a 2D field of view (MSDP). The
spectropolarimetry of THEMIS (Tenerife) allowed us to derive the
magnetic field of the prominence using the He D3 line
depolarization (Hanle effect combined with the Zeeman effect). 
Results: The magnetic field is found to be globally horizontal with
a relatively weak field strength (8-15 Gauss). On the other hand,
the Ca II movie reveals turbulent-like motion that is not organized in
specific parts of the prominence. We tested the addition of a turbulent
magnetic component. This model is compatible with the polarimetric
observations at those places where the plasma turbulence peaks. On the
other hand, the Mg II line profiles show multiple peaks well separated
in wavelength. This is interpreted by the existence of small threads
along the line of sight with a large dispersion of discrete values of
Doppler shifts, from 5 km s-1 (a quasi-steady component) to
60-80 km s-1. Each peak corresponds to a Gaussian profile,
and not to a reversed profile as was expected by the present non-LTE
radiative transfer modeling. This is a very surprising behavior for
the Mg II line observed in prominences. Conclusions: Turbulent
fields on top of the macroscopic horizontal component of the magnetic
field supporting the prominence give rise to the complex dynamics of
the plasma. The plasma with the high velocities (70 km s-1 to
100 km s-1 if we take into account the transverse velocities)
may correspond to condensation of plasma along more or less horizontal
threads of the arch-shape structure visible in 304 Å. The steady
flows (5 km s-1) would correspond to a more quiescent plasma
(cool and prominence-corona transition region) of the prominence packed
into dips in horizontal magnetic field lines. The very weak secondary
peaks in the Mg II profiles may reflect the turbulent nature of parts
of the prominence. Movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423922/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: An Interface Region Imaging Spectrograph First View on Solar
Spicules
Authors: Pereira, T. M. D.; De Pontieu, B.; Carlsson, M.; Hansteen,
V.; Tarbell, T. D.; Lemen, J.; Title, A.; Boerner, P.; Hurlburt,
N.; Wülser, J. P.; Martínez-Sykora, J.; Kleint, L.; Golub, L.;
McKillop, S.; Reeves, K. K.; Saar, S.; Testa, P.; Tian, H.; Jaeggli,
S.; Kankelborg, C.
2014ApJ...792L..15P Altcode: 2014arXiv1407.6360P
Solar spicules have eluded modelers and observers for decades. Since
the discovery of the more energetic type II, spicules have become
a heated topic but their contribution to the energy balance of the
low solar atmosphere remains unknown. Here we give a first glimpse of
what quiet-Sun spicules look like when observed with NASA's recently
launched Interface Region Imaging Spectrograph (IRIS). Using IRIS
spectra and filtergrams that sample the chromosphere and transition
region, we compare the properties and evolution of spicules as
observed in a coordinated campaign with Hinode and the Atmospheric
Imaging Assembly. Our IRIS observations allow us to follow the thermal
evolution of type II spicules and finally confirm that the fading
of Ca II H spicules appears to be caused by rapid heating to higher
temperatures. The IRIS spicules do not fade but continue evolving,
reaching higher and falling back down after 500-800 s. Ca II H type
II spicules are thus the initial stages of violent and hotter events
that mostly remain invisible in Ca II H filtergrams. These events
have very different properties from type I spicules, which show lower
velocities and no fading from chromospheric passbands. The IRIS spectra
of spicules show the same signature as their proposed disk counterparts,
reinforcing earlier work. Spectroheliograms from spectral rasters also
confirm that quiet-Sun spicules originate in bushes from the magnetic
network. Our results suggest that type II spicules are indeed the
site of vigorous heating (to at least transition region temperatures)
along extensive parts of the upward moving spicular plasma.

---------------------------------------------------------
Title: Observations of Subarcsecond Bright Dots in the Transition
Region above Sunspots with the Interface Region Imaging Spectrograph
Authors: Tian, H.; Kleint, L.; Peter, H.; Weber, M.; Testa, P.;
DeLuca, E.; Golub, L.; Schanche, N.
2014ApJ...790L..29T Altcode: 2014arXiv1407.1060T
Observations with the Interface Region Imaging Spectrograph (IRIS)
have revealed numerous sub-arcsecond bright dots in the transition
region above sunspots. These bright dots are seen in the 1400 Å and
1330 Å slit-jaw images. They are clearly present in all sunspots we
investigated, mostly in the penumbrae, but also occasionally in some
umbrae and light bridges. The bright dots in the penumbrae typically
appear slightly elongated, with the two dimensions being 300-600 km and
250-450 km, respectively. The long sides of these dots are often nearly
parallel to the bright filamentary structures in the penumbrae but
sometimes clearly deviate from the radial direction. Their lifetimes
are mostly less than one minute, although some dots last for a few
minutes or even longer. Their intensities are often a few times stronger
than the intensities of the surrounding environment in the slit-jaw
images. About half of the bright dots show apparent movement with
speeds of ~10-40 km s-1 in the radial direction. Spectra of
a few bright dots were obtained and the Si IV 1402.77 Å line profiles
in these dots are significantly broadened. The line intensity can be
enhanced by one to two orders of magnitude. Some relatively bright
and long-lasting dots are also observed in several passbands of the
Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory,
and they appear to be located at the bases of loop-like structures. Many
of these bright dots are likely associated with small-scale energy
release events at the transition region footpoints of magnetic loops.

---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS)
Authors: De Pontieu, B.; Title, A. M.; Lemen, J. R.; Kushner, G. D.;
Akin, D. J.; Allard, B.; Berger, T.; Boerner, P.; Cheung, M.; Chou,
C.; Drake, J. F.; Duncan, D. W.; Freeland, S.; Heyman, G. F.; Hoffman,
C.; Hurlburt, N. E.; Lindgren, R. W.; Mathur, D.; Rehse, R.; Sabolish,
D.; Seguin, R.; Schrijver, C. J.; Tarbell, T. D.; Wülser, J. -P.;
Wolfson, C. J.; Yanari, C.; Mudge, J.; Nguyen-Phuc, N.; Timmons,
R.; van Bezooijen, R.; Weingrod, I.; Brookner, R.; Butcher, G.;
Dougherty, B.; Eder, J.; Knagenhjelm, V.; Larsen, S.; Mansir, D.;
Phan, L.; Boyle, P.; Cheimets, P. N.; DeLuca, E. E.; Golub, L.;
Gates, R.; Hertz, E.; McKillop, S.; Park, S.; Perry, T.; Podgorski,
W. A.; Reeves, K.; Saar, S.; Testa, P.; Tian, H.; Weber, M.; Dunn, C.;
Eccles, S.; Jaeggli, S. A.; Kankelborg, C. C.; Mashburn, K.; Pust, N.;
Springer, L.; Carvalho, R.; Kleint, L.; Marmie, J.; Mazmanian, E.;
Pereira, T. M. D.; Sawyer, S.; Strong, J.; Worden, S. P.; Carlsson,
M.; Hansteen, V. H.; Leenaarts, J.; Wiesmann, M.; Aloise, J.; Chu,
K. -C.; Bush, R. I.; Scherrer, P. H.; Brekke, P.; Martinez-Sykora,
J.; Lites, B. W.; McIntosh, S. W.; Uitenbroek, H.; Okamoto, T. J.;
Gummin, M. A.; Auker, G.; Jerram, P.; Pool, P.; Waltham, N.
2014SoPh..289.2733D Altcode: 2014arXiv1401.2491D; 2014SoPh..tmp...25D
The Interface Region Imaging Spectrograph (IRIS) small explorer
spacecraft provides simultaneous spectra and images of the photosphere,
chromosphere, transition region, and corona with 0.33 - 0.4 arcsec
spatial resolution, two-second temporal resolution, and 1 km
s−1 velocity resolution over a field-of-view of up to
175 arcsec × 175 arcsec. IRIS was launched into a Sun-synchronous
orbit on 27 June 2013 using a Pegasus-XL rocket and consists of a
19-cm UV telescope that feeds a slit-based dual-bandpass imaging
spectrograph. IRIS obtains spectra in passbands from 1332 - 1358 Å,
1389 - 1407 Å, and 2783 - 2834 Å, including bright spectral lines
formed in the chromosphere (Mg II h 2803 Å and Mg II k 2796 Å) and
transition region (C II 1334/1335 Å and Si IV 1394/1403 Å). Slit-jaw
images in four different passbands (C II 1330, Si IV 1400, Mg II k
2796, and Mg II wing 2830 Å) can be taken simultaneously with spectral
rasters that sample regions up to 130 arcsec × 175 arcsec at a variety
of spatial samplings (from 0.33 arcsec and up). IRIS is sensitive to
emission from plasma at temperatures between 5000 K and 10 MK and will
advance our understanding of the flow of mass and energy through an
interface region, formed by the chromosphere and transition region,
between the photosphere and corona. This highly structured and dynamic
region not only acts as the conduit of all mass and energy feeding
into the corona and solar wind, it also requires an order of magnitude
more energy to heat than the corona and solar wind combined. The
IRIS investigation includes a strong numerical modeling component
based on advanced radiative-MHD codes to facilitate interpretation of
observations of this complex region. Approximately eight Gbytes of data
(after compression) are acquired by IRIS each day and made available
for unrestricted use within a few days of the observation.

---------------------------------------------------------
Title: Detection of Supersonic Downflows and Associated Heating
Events in the Transition Region above Sunspots
Authors: Kleint, L.; Antolin, P.; Tian, H.; Judge, P.; Testa, P.;
De Pontieu, B.; Martínez-Sykora, J.; Reeves, K. K.; Wuelser, J. P.;
McKillop, S.; Saar, S.; Carlsson, M.; Boerner, P.; Hurlburt, N.; Lemen,
J.; Tarbell, T. D.; Title, A.; Golub, L.; Hansteen, V.; Jaeggli, S.;
Kankelborg, C.
2014ApJ...789L..42K Altcode: 2014arXiv1406.6816K
Interface Region Imaging Spectrograph data allow us to study the solar
transition region (TR) with an unprecedented spatial resolution of
0.”33. On 2013 August 30, we observed bursts of high Doppler shifts
suggesting strong supersonic downflows of up to 200 km s-1
and weaker, slightly slower upflows in the spectral lines Mg II h
and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated
with brightenings in the slitjaw images (SJIs). The bursty behavior
lasts throughout the 2 hr observation, with average burst durations
of about 20 s. The locations of these short-lived events appear to
be the umbral and penumbral footpoints of EUV loops. Fast apparent
downflows are observed along these loops in the SJIs and in the
Atmospheric Imaging Assembly, suggesting that the loops are thermally
unstable. We interpret the observations as cool material falling
from coronal heights, and especially coronal rain produced along the
thermally unstable loops, which leads to an increase of intensity
at the loop footpoints, probably indicating an increase of density
and temperature in the TR. The rain speeds are on the higher end of
previously reported speeds for this phenomenon, and possibly higher
than the free-fall velocity along the loops. On other observing days,
similar bright dots are sometimes aligned into ribbons, resembling
small flare ribbons. These observations provide a first insight into
small-scale heating events in sunspots in the TR.

---------------------------------------------------------
Title: Dynamics of the Transition Corona
Authors: Masson, Sophie; McCauley, Patrick; Golub, Leon; Reeves,
Katharine K.; DeLuca, Edward E.
2014ApJ...787..145M Altcode: 2013arXiv1301.0740M
Magnetic reconnection between the open and closed magnetic fields in
the corona is believed to play a crucial role in the corona/heliosphere
coupling. At large scale, the exchange of open/closed connectivity is
expected to occur in pseudo-streamer (PS) structures. However, there
is neither clear observational evidence of how such coupling occurs
in PSs, nor evidence for how the magnetic reconnection evolves. Using
a newly developed technique, we enhance the off-limb magnetic fine
structures observed with the Atmospheric Imaging Assembly and identify
a PS-like feature located close to the northern coronal hole. We first
identify that the magnetic topology associated with the observation is
a PS, null-point (NP) related topology bounded by the open field. By
comparing the magnetic field configuration with the EUV emission
regions, we determined that most of the magnetic flux associated with
plasma emission are small loops below the PS basic NP and open field
bounding the PS topology. In order to interpret the evolution of the
PS, we referred to a three-dimensional MHD interchange reconnection
modeling the exchange of connectivity between small closed loops and the
open field. The observed PS fine structures follow the dynamics of the
magnetic field before and after reconnecting at the NP obtained by the
interchange model. Moreover, the pattern of the EUV plasma emission is
the same as the shape of the expected plasma emission location derived
from the simulation. These morphological and dynamical similarities
between the PS observations and the results from the simulation
strongly suggest that the evolution of the PS, and in particular
the opening/closing of the field, occurs via interchange/slipping
reconnection at the basic NP of the PS. Besides identifying the
mechanism at work in the large-scale coupling between the open and
closed fields, our results highlight that interchange reconnection
in PSs is a gradual physical process that differs from the impulsive
reconnection of the solar-jet model.

---------------------------------------------------------
Title: The Substructure of the Solar Corona Observed in the Hi-C
Telescope
Authors: Winebarger, Amy R.; Cirtain, Jonathan W.; Golub, Leon;
DeLuca, Ed; Savage, Sabrina; Alexander, Caroline; Schuler, Timothy
2014AAS...22432320W Altcode:
In the summer of 2012, the High-resolution Coronal Imager (Hi-C)
flew aboard a NASA sounding rocket and collected the highest spatial
resolution images ever obtained of the solar corona. One of the
goals of the Hi-C flight was to characterize the substructure of the
solar corona. We therefore calculate how the intensity scales from a
low-resolution (AIA) pixels to high-resolution (Hi-C) pixels for both
the dynamic events and “background” emission (meaning, the steady
emission over the 5 minutes of data acquisition time). We find there
is no evidence of substructure in the background corona; the intensity
scales smoothly from low-resolution to high-resolution Hi-C pixels. In
transient events, however, the intensity observed with Hi-C is, on
average, 2.6 times larger than observed with AIA. This increase in
intensity suggests that AIA is not resolving these events. This result
suggests a finely structured dynamic corona embedded in a smoothly
varying background.

---------------------------------------------------------
Title: Visibility of Extended Coronal Structures and CMEs in the EUV
Authors: Schanche, Nicole; Golub, Leon
2014AAS...22432347S Altcode:
Extended coronal structures around active regions and coronal mass
ejections (CMEs) have often been seen in the extreme-ultraviolet (EUV)
channels to the full extent of the AIA and SWAP field of views 1.3 and
1.7 Rsun). Using off-pointed comet data in AIA we sum a large number
of frames to evaluate the off-limb distance to which streamers can be
detected. For CMEs, we compared the events classified as halo CMEs in
the white-light LASCO CACTus catalog from July-September 2013 to the
AIA and SWAP data collected around those events. We discovered that
roughly 80% of events could be seen in the EUV using both regular
and running difference movies, with the most effective channels being
the 193 and 304Å channels. By projecting out the signal strength of
several of these events, we conclude that these EUV events can in many
cases be detected to over 2.5 Rsun. A larger field-of-view telescope
would make it possible to track the development of these structures
and events from the disk out to several solar radii, complementing
the traditional white-light methods.

---------------------------------------------------------
Title: An Airborne Infrared Telescope and Spectrograph for Solar
Eclipse Observations
Authors: DeLuca, Edward E.; Cheimets, Peter; Golub, Leon
2014AAS...22412356D Altcode:
The solar infrared spectrum offers great possibilities for direct
spatially resolved measurements of the solar coronal magnetic fields,
via imaging of the plasma that is constrained to follow the magnetic
field direction and via spectro-polarimetry that permits measurement
of the field strength in the corona. Energy stored in coronal magnetic
fields is released in flares and coronal mass ejections (CME) and
provides the ultimate source of energy for space weather. The large
scale structure of the coronal field, and the opening up of the field
in a transition zone between the closed and open corona determines
the speed and structure of the solar wind, providing the background
environment through which CMEs propagate. At present our only direct
measurements of the solar magnetic fields are in the photosphere
and chromosphere. The ability to determine where and why the corona
transitions from closed to open, combined with measurements of the
field strength via infrared coronal spectro-polarimetry will give us
a powerful new tool in our quest to develop the next generation of
forecasting models.We describe a first step in achieving this goal:
a proposal for a new IR telescope, image stabilization system, and
spectrometer, for the NCAR HIPER GV aircraft. The telescope/spectrograph
will operate in the 2-6micron wavelength region, during solar eclipses,
starting with the trans-north American eclipse in August 2017. The
HIAPER aircraft flying at ~35,000 ft will provide an excellent platform
for IR observations. Our imaging and spectroscopy experiment will
show the distribution and intensity of IR forbidden lines in the
solar corona.

---------------------------------------------------------
Title: High-resolution Laboratory Measurements of Coronal Lines in
the 198-218 Å Region
Authors: Beiersdorfer, Peter; Träbert, Elmar; Lepson, Jaan K.;
Brickhouse, Nancy S.; Golub, Leon
2014ApJ...788...25B Altcode:
We present high-resolution laboratory measurements of the emission
from various ions of C, N, O, F, Ne, S, Ar, Fe, and Ni in the
extreme ultraviolet wavelength band centered around the λ211 Fe XIV
channel of the Atmospheric Imaging Assembly on the Solar Dynamics
Observatory. While all of the strong iron lines in this region
are well known, we note many weaker lines of iron that are not yet
identified. The high resolution of our measurements also allows us to
resolve several lines in Fe XI, Fe XII, and Fe XIII between 200 and 205
Å, whose identities were in question based on a disagreement between
different databases. The spectra of the elements other than iron are
much less known, and we find a multitude of lines that are not yet
in the databases. For example, the CHIANTI database clearly disagrees
with the NIST data listings on several of the argon lines we observe
and also it contains only about half of the observed sulfur lines.

---------------------------------------------------------
Title: Discovery of Finely Structured Dynamic Solar Corona Observed
in the Hi-C Telescope
Authors: Winebarger, Amy R.; Cirtain, Jonathan; Golub, Leon; DeLuca,
Edward; Savage, Sabrina; Alexander, Caroline; Schuler, Timothy
2014ApJ...787L..10W Altcode:
In the Summer of 2012, the High-resolution Coronal Imager (Hi-C)
flew on board a NASA sounding rocket and collected the highest
spatial resolution images ever obtained of the solar corona. One of
the goals of the Hi-C flight was to characterize the substructure of
the solar corona. We therefore examine how the intensity scales from
AIA resolution to Hi-C resolution. For each low-resolution pixel, we
calculate the standard deviation in the contributing high-resolution
pixel intensities and compare that to the expected standard deviation
calculated from the noise. If these numbers are approximately equal,
the corona can be assumed to be smoothly varying, i.e., have no evidence
of substructure in the Hi-C image to within Hi-C's ability to measure
it given its throughput and readout noise. A standard deviation much
larger than the noise value indicates the presence of substructure. We
calculate these values for each low-resolution pixel for each frame
of the Hi-C data. On average, 70% of the pixels in each Hi-C image
show no evidence of substructure. The locations where substructure is
prevalent is in the moss regions and in regions of sheared magnetic
field. We also find that the level of substructure varies significantly
over the roughly 160 s of the Hi-C data analyzed here. This result
indicates that the finely structured corona is concentrated in regions
of heating and is highly time dependent.

---------------------------------------------------------
Title: High-resolution Observations of the Shock Wave Behavior for
Sunspot Oscillations with the Interface Region Imaging Spectrograph
Authors: Tian, H.; DeLuca, E.; Reeves, K. K.; McKillop, S.; De Pontieu,
B.; Martínez-Sykora, J.; Carlsson, M.; Hansteen, V.; Kleint, L.;
Cheung, M.; Golub, L.; Saar, S.; Testa, P.; Weber, M.; Lemen, J.;
Title, A.; Boerner, P.; Hurlburt, N.; Tarbell, T. D.; Wuelser, J. P.;
Kankelborg, C.; Jaeggli, S.; McIntosh, S. W.
2014ApJ...786..137T Altcode: 2014arXiv1404.6291T
We present the first results of sunspot oscillations from observations
by the Interface Region Imaging Spectrograph. The strongly nonlinear
oscillation is identified in both the slit-jaw images and the
spectra of several emission lines formed in the transition region and
chromosphere. We first apply a single Gaussian fit to the profiles of
the Mg II 2796.35 Å, C II 1335.71 Å, and Si IV 1393.76 Å lines in the
sunspot. The intensity change is ~30%. The Doppler shift oscillation
reveals a sawtooth pattern with an amplitude of ~10 km s-1
in Si IV. The Si IV oscillation lags those of C II and Mg II by ~3 and
~12 s, respectively. The line width suddenly increases as the Doppler
shift changes from redshift to blueshift. However, we demonstrate
that this increase is caused by the superposition of two emission
components. We then perform detailed analysis of the line profiles at
a few selected locations on the slit. The temporal evolution of the
line core is dominated by the following behavior: a rapid excursion
to the blue side, accompanied by an intensity increase, followed by a
linear decrease of the velocity to the red side. The maximum intensity
slightly lags the maximum blueshift in Si IV, whereas the intensity
enhancement slightly precedes the maximum blueshift in Mg II. We find
a positive correlation between the maximum velocity and deceleration,
a result that is consistent with numerical simulations of upward
propagating magnetoacoustic shock waves.

---------------------------------------------------------
Title: Sparkling Extreme-ultraviolet Bright Dots Observed with Hi-C
Authors: Régnier, S.; Alexander, C. E.; Walsh, R. W.; Winebarger,
A. R.; Cirtain, J.; Golub, L.; Korreck, K. E.; Mitchell, N.; Platt,
S.; Weber, M.; De Pontieu, B.; Title, A.; Kobayashi, K.; Kuzin, S.;
DeForest, C. E.
2014ApJ...784..134R Altcode: 2014arXiv1402.2457R
Observing the Sun at high time and spatial scales is a step toward
understanding the finest and fundamental scales of heating events
in the solar corona. The high-resolution coronal (Hi-C) instrument
has provided the highest spatial and temporal resolution images of
the solar corona in the EUV wavelength range to date. Hi-C observed
an active region on 2012 July 11 that exhibits several interesting
features in the EUV line at 193 Å. One of them is the existence
of short, small brightenings "sparkling" at the edge of the active
region; we call these EUV bright dots (EBDs). Individual EBDs have a
characteristic duration of 25 s with a characteristic length of 680
km. These brightenings are not fully resolved by the SDO/AIA instrument
at the same wavelength; however, they can be identified with respect
to the Hi-C location of the EBDs. In addition, EBDs are seen in other
chromospheric/coronal channels of SDO/AIA, which suggests a temperature
between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time
series, we define four different categories of EBDs: single peak,
double peak, long duration, and bursty. Based on a potential field
extrapolation from an SDO/HMI magnetogram, the EBDs appear at the
footpoints of large-scale, trans-equatorial coronal loops. The Hi-C
observations provide the first evidence of small-scale EUV heating
events at the base of these coronal loops, which have a free magnetic
energy of the order of 1026 erg.

---------------------------------------------------------
Title: Nearest Star
Authors: Golub, Leon; Pasachoff, Jay M.
2014nest.book.....G Altcode:
Preface; Acknowledgments; 1. The Sun; 2. The once and future Sun;
3. What we see: the solar disk; 4. What we don't see; 5. Eclipses;
6. Space missions; 7. Between fire and ice; 8. Space weather;
Bibliography; Glossary; Index.

---------------------------------------------------------
Title: High-resolution Laboratory Spectra on the λ131 Channel of
the AIA Instrument On Board the Solar Dynamics Observatory
Authors: Träbert, Elmar; Beiersdorfer, Peter; Brickhouse, Nancy S.;
Golub, Leon
2014ApJS..211...14T Altcode:
Extreme ultraviolet spectra of C, O, F, Ne, Si, S, Ar, Ca, Fe, and
Ni have been excited in an electron beam ion trap and studied with
much higher resolution than available on Solar Dynamics Observatory
(SDO) in order to ascertain the spectral composition of the SDO
observations. We presently show our findings in the wavelength range
124-134 Å, which encompasses the λ131 observation channel of the
Atmospheric Imaging Assembly (AIA). While the general interpretation of
the spectral composition of the λ131 Fe channel is being corroborated,
a number of new lines have been observed that might help to improve
the diagnostic value of the SDO/AIA data.

---------------------------------------------------------
Title: Diagnostics for the O IV and Si IV lines observed by IRIS
Authors: Dudik, Jaroslav; Mason, Helen; Del Zanna, Giulio; Golub,
Leon; Dzifcakova, Elena
2014cosp...40E.754D Altcode:
We investigate the formation of the IRIS O IV and Si IV lines under
non-Maxwellian conditions characterized by kappa-distributions. It is
found that the Si IV lines are always formed at lower temperatures
than the O IV lines. However, as the departure from the Maxwellian
increases, the peak formation temperatures are shifted progressively to
lower and lower temperatures. Coupled with the slope of the differential
emission measure (DEM), it is possible for the Si IV lines to be formed
very close to the solar chromosphere, with the majority of the O IV
intensities coming from a different, higher part of the transition
region. The predicted spectra for kappa-distributions exhibit very low O
IV intensities compared to Si IV, analogously to what is observed by the
IRIS spacecraft. Potential density diagnostics are discussed, as well
as the contribution of photoexcitation to the formation of these lines.

---------------------------------------------------------
Title: Observation of nano-flares and transient coronal heating
Authors: Serge, Koutchmy; Golub, Leon; Bazin, Cyrille; Tavabi, Ehsan
2014cosp...40E2970S Altcode:
Nano-flares are the best candidate for heating the bulk of the corona
but their signature is still not clearly recognized in the data. The
Hinode XRT provided many high resolution partial frame sequences that
allowed study of intermittent flash events in quiet areas, suggesting a
definite signature of nano-flares. The Yohkoh so-called SXR transient
brightenings are now recorded by XRT with a wealth of detail. The
typical resolution and low noise of XRT permits detection at a much
lower intensity threshold and a much shorter duration. In order to
evaluate what is a nano-flare, we selected a well-observed solar disk
event seen at the beginning of the XRT mission, when the Sun was still
very quiet. This single flare event is recorded outside of any active
region and does not show any GOES or RHESSI signature, even at the
lowest level. This nano-flare shows structures suggestive of rather
horizontal low lying loops with a short intense flash phase. No jet
is observed. EUV brightening counterparts exist, including the 304Å
TR emission, detected by the SECCHI EUV imagers on the two STEREO
spacecrafts. Filtergrams taken simultaneously at a fast rate in Hα
are deeply processed to look at the resulting effects, seen as a faint
brightening and a cool transient very small scale feature. We argue in
favor of many similar SXR events permanently occurring at the TR levels,
not showing strong EUV brightenings but with horizontally stretched
structures similar to the recently described Hi-C reconnection events
called magnetic “braids” that include twists and possibly counter
flows.

---------------------------------------------------------
Title: Total mass loading of prominences estimated from their
multi-spectral observations
Authors: Schwartz, Pavol; Heinzel, Peter; Kotrč, Pavel; Fárník,
František; Kupryakov, Yurij A.; DeLuca, Edward E.; Golub, Leon
2014IAUS..300..458S Altcode:
The total mass of several quiescent prominences observed in EUV by
the AIA instrument on board SDO, in soft X-rays by XRT on Hinode and
in Hα and CaII H by the SLS and HSFA spectrographs of the Ondřejov
observatory, was estimated. Values of asymmetry of coronal emissivity
obtained during the mass computations are compared with those estimated
from 193 Å intensities measured at the disk edge and just above
the limb.

---------------------------------------------------------
Title: Solar Transition Region Lines Observed by the Interface Region
Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
Authors: Dudík, J.; Del Zanna, G.; Dzifčáková, E.; Mason, H. E.;
Golub, L.
2014ApJ...780L..12D Altcode: 2013arXiv1311.6978D
The formation of the transition region O IV and Si IV lines observable
by the Interface Region Imaging Spectrograph (IRIS) is investigated
for both Maxwellian and non-Maxwellian conditions characterized by
a κ-distribution exhibiting a high-energy tail. The Si IV lines
are formed at lower temperatures than the O IV lines for all κ. In
non-Maxwellian situations with lower κ, the contribution functions
are shifted to lower temperatures. Combined with the slope of the
differential emission measure, it is possible for the Si IV lines to be
formed at very different regions of the solar transition region than the
O IV lines; possibly close to the solar chromosphere. Such situations
might be discernible by IRIS. It is found that photoexcitation can be
important for the Si IV lines, but is negligible for the O IV lines. The
usefulness of the O IV ratios for density diagnostics independently of
κ is investigated and it is found that the O IV 1404.78 Å/1399.77
Å ratio provides a good density diagnostics except for very low T
combined with extreme non-Maxwellian situations.

---------------------------------------------------------
Title: Anti-parallel EUV Flows Observed along Active Region Filament
Threads with Hi-C
Authors: Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane;
Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi,
Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart;
DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey
2013ApJ...775L..32A Altcode: 2013arXiv1306.5194A
Plasma flows within prominences/filaments have been observed for
many years and hold valuable clues concerning the mass and energy
balance within these structures. Previous observations of these flows
primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g.,
304 Å) where estimates of the size of the prominence threads has been
limited by the resolution of the available instrumentation. Evidence of
"counter-steaming" flows has previously been inferred from these cool
plasma observations, but now, for the first time, these flows have been
directly imaged along fundamental filament threads within the million
degree corona (at 193 Å). In this work, we present observations
of an AR filament observed with the High-resolution Coronal Imager
(Hi-C) that exhibits anti-parallel flows along adjacent filament
threads. Complementary data from the Solar Dynamics Observatory
(SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic
Imager are presented. The ultra-high spatial and temporal resolution
of Hi-C allow the anti-parallel flow velocities to be measured (70-80
km s-1) and gives an indication of the resolvable thickness
of the individual strands (0.”8 ± 0.”1). The temperature of the
plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission
Measure loci analysis. We find that SDO/AIA cannot clearly observe these
anti-parallel flows or measure their velocity or thread width due to
its larger pixel size. We suggest that anti-parallel/counter-streaming
flows are likely commonplace within all filaments and are currently
not observed in EUV due to current instrument spatial resolution.

---------------------------------------------------------
Title: Structure of solar coronal loops: from miniature to large-scale
Authors: Peter, H.; Bingert, S.; Klimchuk, J. A.; de Forest, C.;
Cirtain, J. W.; Golub, L.; Winebarger, A. R.; Kobayashi, K.; Korreck,
K. E.
2013A&A...556A.104P Altcode: 2013arXiv1306.4685P
 Aims: We use new data from the High-resolution Coronal Imager
(Hi-C) with its unprecedented spatial resolution of the solar corona
to investigate the structure of coronal loops down to 0.2”. 
Methods: During a rocket flight, Hi-C provided images of the solar
corona in a wavelength band around 193 Å that is dominated by emission
from Fe xii showing plasma at temperatures around 1.5 MK. We analyze
part of the Hi-C field-of-view to study the smallest coronal loops
observed so far and search for the possible substructuring of larger
loops. Results: We find tiny 1.5 MK loop-like structures that
we interpret as miniature coronal loops. Their coronal segments above
the chromosphere have a length of only about 1 Mm and a thickness of
less than 200 km. They could be interpreted as the coronal signature
of small flux tubes breaking through the photosphere with a footpoint
distance corresponding to the diameter of a cell of granulation. We
find that loops that are longer than 50 Mm have diameters of about 2”
or 1.5 Mm, which is consistent with previous observations. However, Hi-C
really resolves these loops with some 20 pixels across the loop. Even
at this greatly improved spatial resolution, the large loops seem to
have no visible substructure. Instead they show a smooth variation in
cross-section. Conclusions: That the large coronal loops do not
show a substructure on the spatial scale of 0.1” per pixel implies that
either the densities and temperatures are smoothly varying across these
loops or it places an upper limit on the diameter of the strands the
loops might be composed of. We estimate that strands that compose the
2” thick loop would have to be thinner than 15 km. The miniature loops
we find for the first time pose a challenge to be properly understood
through modeling. Appendices are available in electronic form at
<A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Evidence for the release of magnetic free energy using Hi-C
observations
Authors: Cirtain, Jonathan W.; Winebarger, A. R.; Golub, L.; Korreck,
K. E.; Kobayashi, K.
2013SPD....4420001C Altcode:
The Hi-C sounding rocket data can be used to determine the rate and
approximate magnitude of free energy released by the active region
coronal magnetic field. We present the results from the analysis of
two regions within the Hi-C field-of-view. Hi-C data is also used
to determine the temperature and density of structures and we offer
conclusions on the spatial scale for these features.

---------------------------------------------------------
Title: Detecting Nanoflare Heating Events in Subarcsecond Inter-moss
Loops Using Hi-C
Authors: Winebarger, Amy R.; Walsh, Robert W.; Moore, Ronald;
De Pontieu, Bart; Hansteen, Viggo; Cirtain, Jonathan; Golub, Leon;
Kobayashi, Ken; Korreck, Kelly; DeForest, Craig; Weber, Mark; Title,
Alan; Kuzin, Sergey
2013ApJ...771...21W Altcode:
The High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding
rocket on 2012 July 11 and captured roughly 345 s of high-spatial and
temporal resolution images of the solar corona in a narrowband 193 Å
channel. In this paper, we analyze a set of rapidly evolving loops that
appear in an inter-moss region. We select six loops that both appear in
and fade out of the Hi-C images during the short flight. From the Hi-C
data, we determine the size and lifetimes of the loops and characterize
whether these loops appear simultaneously along their length or
first appear at one footpoint before appearing at the other. Using
co-aligned, co-temporal data from multiple channels of the Atmospheric
Imaging Assembly on the Solar Dynamics Observatory, we determine the
temperature and density of the loops. We find the loops consist of
cool (~105 K), dense (~1010 cm-3)
plasma. Their required thermal energy and their observed evolution
suggest they result from impulsive heating similar in magnitude to
nanoflares. Comparisons with advanced numerical simulations indicate
that such dense, cold and short-lived loops are a natural consequence
of impulsive magnetic energy release by reconnection of braided magnetic
field at low heights in the solar atmosphere.

---------------------------------------------------------
Title: Dynamics of the Transition Corona
Authors: Masson, Sophie; McCauley, P.; Golub, L.; Reeves, K.; DeLuca,
E. E.
2013SPD....44...27M Altcode:
Magnetic reconnection between open and closed magnetic field in the
corona is believed to play a crucial role in the corona / heliosphere
coupling. At large scale, the exchange of open /closed connectivity
is expected to occur in pseudo-streamer structures. However,
there is neither clear observational evidence of how such coupling
occurs in pseudo-streamers, nor evidence for how the magnetic
reconnection evolves. Using a newly-developed technique, we enhance
the off-limb magnetic fine structures observed with AIA and identify
a pseudo-streamer-like feature located close to the northern coronal
hole. We first identify that the magnetic topology associated with the
observation is a pseudo-streamer, null-point-related topology bounded
by open field. We then compare the evolution of the observed pseudo-
streamer fine structure in the location of strong currents, i.e. in
the region of energy dissipation, with the dynamics of the magnetic
field resulting from the interchange reconnection obtained in a fully
3D MHD simulation. The morphological and dynamical similarities between
the pseudo-streamer observations and the results from the simulation
strongly suggest that the evolution of the pseudo-streamer is caused
by interchange reconnection in a null-point topology that is embedded
in Quasi-Separatrix layers. Besides identifying the mechanism at work
in the large-scale coupling between open and closed field, our results
highlight that interchange reconnection in pseudo-streamers is a gradual
physical process that differs from the impulsive reconnection of the
solar-jet model.

---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS)
Authors: De Pontieu, Bart; Title, A. M.; Lemen, J.; Wuelser, J.;
Tarbell, T. D.; Schrijver, C. J.; Golub, L.; Kankelborg, C.; Carlsson,
M.; Hansteen, V. H.; Worden, S.; IRIS Team
2013SPD....44...03D Altcode:
The solar chromosphere and transition region (TR) form a highly
structured and dynamic interface region between the photosphere and
the corona. This region not only acts as the conduit of all mass and
energy feeding into the corona and solar wind, it also requires an
order of magnitude more energy to heat than the corona. Nevertheless,
the chromosphere remains poorly understood, because of the complexity
of the required observational and analytical tools: the interface
region is highly complex with transitions from optically thick to
optically thin radiation, from pressure to magnetic field domination,
and large density and temperature contrasts on small spatial scales. The
Interface Region Imaging Spectrograph (IRIS) was selected for a NASA
SMEX mission in 2009 and is scheduled to launch on 26-June-2013 (with
first light scheduled for mid July). IRIS addresses critical questions:
(1) Which types of non-thermal energy dominate in the chromosphere and
beyond? (2) How does the chromosphere regulate mass and energy supply
to the corona and heliosphere? (3) How do magnetic flux and matter
rise through the lower atmosphere, and what role does flux emergence
play in flares and mass ejections? These questions are addressed with
a high-resolution near and far UV imaging spectrometer sensitive to
emission from plasma at temperatures between 5,000 K and 10 MK. IRIS
has a field-of-view of 120 arcsec, a spatial resolution of 0.4 arcsec,
and velocity resolution of 0.5 km/s. The IRIS investigation includes
a strong numerical modeling component based on advanced radiative MHD
codes to facilitate interpretation of observations. We describe the
IRIS instrumentation and numerical modeling, and present the plans for
observations, calibration and data distribution. We will highlight some
of the issues that IRIS observations can help resolve. More information
can be found at http://iris.lmsal.com

---------------------------------------------------------
Title: Observing Coronal Nanoflares in Active Region Moss
Authors: Testa, Paola; De Pontieu, Bart; Martínez-Sykora, Juan;
DeLuca, Ed; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy;
Golub, Leon; Kobayashi, Ken; Korreck, Kelly; Kuzin, Sergey; Walsh,
Robert; DeForest, Craig; Title, Alan; Weber, Mark
2013ApJ...770L...1T Altcode: 2013arXiv1305.1687T
The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193Å
images of the upper transition region moss at an unprecedented spatial
(~0.”3-0.”4) and temporal (5.5 s) resolution. The Hi-C observations
show in some moss regions variability on timescales down to ~15 s,
significantly shorter than the minute-scale variability typically found
in previous observations of moss, therefore challenging the conclusion
of moss being heated in a mostly steady manner. These rapid variability
moss regions are located at the footpoints of bright hot coronal
loops observed by the Solar Dynamics Observatory/Atmospheric Imaging
Assembly in the 94 Å channel, and by the Hinode/X-Ray Telescope. The
configuration of these loops is highly dynamic, and suggestive of
slipping reconnection. We interpret these events as signatures of
heating events associated with reconnection occurring in the overlying
hot coronal loops, i.e., coronal nanoflares. We estimate the order
of magnitude of the energy in these events to be of at least a few
1023 erg, also supporting the nanoflare scenario. These
Hi-C observations suggest that future observations at comparable
high spatial and temporal resolution, with more extensive temperature
coverage, are required to determine the exact characteristics of the
heating mechanism(s).

---------------------------------------------------------
Title: Bright Points: Multithermal Analysis as a Test of Steady
Heating Models
Authors: Schmelz, J. T.; Winebarger, A. R.; Kimble, J. A.; Pathak,
S.; Golub, L.; Jenkins, B. S.; Worley, B. T.
2013ApJ...770..160S Altcode:
X-ray bright points are small, million-degree features in the solar
atmosphere composed of short coronal loops. They are magnetically
driven structures associated with photospheric magnetic bipoles. Their
relatively small size and simple structure suggest they are ideal
candidates for comparisons with coronal heating models. In this paper,
we present the analysis of 12 bright points using data from the EUV
Imaging Spectrometer on Hinode and the Michelson Doppler Imager on
Solar and Heliospheric Observatory. Using the spectroscopy data, we
construct differential emission measure (DEM) curves, calculate the
electron density, and find DEM-weighted temperatures. In addition,
we determine the most likely ionization balance. Using the magnetic
field observations, we complete potential field extrapolations of the
magnetograms and estimate the loop lengths. Using this information,
we construct models assuming the bright points are formed of hundreds
of strands, each heated steadily and uniformly. We formulate the models
so that the observed emission measure distribution is matched within a
few percent. We then compare the densities determined from the models,
(1.4-5.0) × 109, to those calculated from spectral data,
(0.6-2.0) × 109. We find the majority of bright points
do not agree with steady uniform heating models; instead they are
underdense relative to their expected density by a factor of 0.16-0.82.

---------------------------------------------------------
Title: SDO/AIA Prominence physical conditions
Authors: Schmieder, B.; Parenti, S.; Dudik, J.; Aulanier, G.; Heinzel,
P.; Zapior, M.; Golub, L.
2013enss.confE..27S Altcode:
SDO/AIA has carried out continuous observations of prominences in
multiple wavelengths, with high spatial and temporal resolution. These
data provide us an opportunity to understand the physical conditions
and dynamics of prominences. The surprising brightness of prominences
in some coronal lines has been well explained by the presence of
transition region lines in the bandpass of the filters (171 A, 131 A),
a result that leads us to revise our model of the transition region
of prominences and to consider a relatively dense transition region in
some prominence evolutionary phases or in some viewing orientation. An
additional aspect of prominence dynamics will be presented with a new
quasi-static MHD model proposed for bubbles and plumes. We propose
an alternative to the interpretation that thermal instabilities are
responsible for the formation of bubbles. The bubbles are found to
correspond to magnetic separatrices formed by emerging magnetic field
close to prominence footpoints.

---------------------------------------------------------
Title: Three 2012 Transits of Venus: From Earth, Jupiter, and Saturn
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
Edelman, E.; Reardon, K.; Widemann, T.; Tanga, P.; Dantowitz, R.;
Silverstone, M. D.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson,
P. D.; Willson, R. C.; Kopp, G. A.; Yurchyshyn, V. B.; Sterling,
A. C.; Scherrer, P. H.; Schou, J.; Golub, L.; McCauley, P.; Reeves, K.
2013AAS...22131506P Altcode:
We observed the 2012 June 6/5 transit seen from Earth (E/ToV),
simultaneously with Venus Express and several other spacecraft
not only to study the Cytherean atmosphere but also to provide an
exoplanet-transit analog. From Haleakala, the whole transit was visible
in coronal skies; among our instruments was one of the world-wide Venus
Twilight Experiment's nine coronagraphs. Venus's atmosphere became
visible before first contact. SacPeak/IBIS provided high-resolution
images at Hα/carbon-dioxide. Big Bear's NST also provided
high-resolution observations of the Cytherean atmosphere and black-drop
evolution. Our liaison with UH's Mees Solar Observatory scientists
provided magneto-optical imaging at calcium and potassium. Solar
Dynamics Observatory's AIA and HMI, and the Solar Optical Telescope
(SOT) and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance
measurements with ACRIMSAT and SORCE/TIM, were used to observe the
event as an exoplanet-transit analog. On September 20, we imaged
Jupiter for 14 Hubble Space Telescope orbits, centered on a 10-hour
ToV visible from Jupiter (J/ToV), as an exoplanet-transit analog in
our own solar system, using Jupiter as an integrating sphere. Imaging
was good, although much work remains to determine if we can detect
the expected 0.01% solar irradiance decrease at Jupiter and the even
slighter differential effect between our violet and near-infrared
filters caused by Venus's atmosphere. We also give a first report on our
currently planned December 21 Cassini UVIS observations of a transit of
Venus from Saturn (S/ToV). Our E/ToV expedition was sponsored by the
Committee for Research and Exploration/National Geographic Society;
supplemented: NASA/AAS's Small Research Grant Program. We thank Rob
Ratkowski, Stan Truitt, Rob Lucas, Aram Friedman, and Eric Pilger
'82 at Haleakala, and Joseph Gangestad '06 at Big Bear for assistance,
and Lockheed Martin Solar and Astrophysics Lab and Hinode science and
operations teams for support for coordinated observations with NASA
satellites. Our J/ToV observations were based on observations made
with HST, operated by AURA, Inc., under NASA contract NAS 5-26555;
these observations are associated with program #13067.

---------------------------------------------------------
Title: Energy release in the solar corona from spatially resolved
magnetic braids
Authors: Cirtain, J. W.; Golub, L.; Winebarger, A. R.; de Pontieu,
B.; Kobayashi, K.; Moore, R. L.; Walsh, R. W.; Korreck, K. E.; Weber,
M.; McCauley, P.; Title, A.; Kuzin, S.; Deforest, C. E.
2013Natur.493..501C Altcode:
It is now apparent that there are at least two heating mechanisms
in the Sun's outer atmosphere, or corona. Wave heating may be the
prevalent mechanism in quiet solar periods and may contribute to
heating the corona to 1,500,000 K (refs 1, 2, 3). The active corona
needs additional heating to reach 2,000,000-4,000,000 K this heat
has been theoretically proposed to come from the reconnection and
unravelling of magnetic `braids'. Evidence favouring that process has
been inferred, but has not been generally accepted because observations
are sparse and, in general, the braided magnetic strands that are
thought to have an angular width of about 0.2 arc seconds have not been
resolved. Fine-scale braiding has been seen in the chromosphere but not,
until now, in the corona. Here we report observations, at a resolution
of 0.2 arc seconds, of magnetic braids in a coronal active region that
are reconnecting, relaxing and dissipating sufficient energy to heat
the structures to about 4,000,000 K. Although our 5-minute observations
cannot unambiguously identify the field reconnection and subsequent
relaxation as the dominant heating mechanism throughout active regions,
the energy available from the observed field relaxation in our example
is ample for the observed heating.

---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS)
Authors: De Pontieu, B.; Title, A. M.; Lemen, J. R.; Wuelser, J.;
Tarbell, T. D.; Schrijver, C.; Golub, L.; Kankelborg, C. C.; Hansteen,
V. H.; Carlsson, M.
2012AGUFMSH33D2256D Altcode:
The solar chromosphere and transition region (TR) form a highly
structured and dynamic interface region between the photosphere and
the corona. This region not only acts as the conduit of all mass and
energy feeding into the corona and solar wind, it also requires an
order of magnitude more energy to heat than the corona. Nevertheless,
the chromosphere remains poorly understood, because of the complexity
of the required observational and analytical tools: the interface
region is highly complex with transitions from optically thick to
optically thin radiation, from pressure to magnetic field domination,
and large density and temperature contrasts on small spatial scales. The
Interface Region Imaging Spectrograph (IRIS) was selected for a NASA
SMEX mission in 2009 and is scheduled to launch in early 2013. IRIS
addresses critical questions: (1) Which types of non-thermal energy
dominate in the chromosphere and beyond? (2) How does the chromosphere
regulate mass and energy supply to the corona and heliosphere? (3)
How do magnetic flux and matter rise through the lower atmosphere, and
what role does flux emergence play in flares and mass ejections? These
questions are addressed with a high-resolution near and far UV imaging
spectrometer sensitive to emission from plasma at temperatures between
5,000 K and 10 MK. IRIS has a field-of-view of 120 arcsec, a spatial
resolution of 0.4 arcsec, and velocity resolution of 0.5 km/s. The
IRIS investigation includes a strong numerical modeling component
based on advanced radiative MHD codes to facilitate interpretation of
observations. We will describe the IRIS instrumentation and numerical
modeling, and present the status of the IRIS observatory development. We
will highlight some of the issues that IRIS observations can help
resolve.

---------------------------------------------------------
Title: Loop Evolution Observed with AIA and Hi-C
Authors: Mulu-Moore, F.; Winebarger, A. R.; Cirtain, J. W.; Kobayashi,
K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest,
C.; De Pontieu, B.; Title, A. M.; Weber, M.
2012AGUFMSH33A2225M Altcode:
In the past decade, the evolution of EUV loops has been used to infer
the loop substructure. With the recent launch of High Resolution Coronal
Imager (Hi-C), this inference can be validated. In this presentation we
discuss the first results of loop analysis comparing AIA and Hi-C data.

---------------------------------------------------------
Title: The Fundamental Structure of Coronal Loops
Authors: Winebarger, A. R.; Warren, H. P.; Cirtain, J. W.; Kobayashi,
K.; Korreck, K. E.; Golub, L.; Kuzin, S.; Walsh, R. W.; DeForest,
C.; De Pontieu, B.; Title, A. M.; Weber, M.
2012AGUFMSH31B..06W Altcode:
During the past ten years, solar physicists have attempted to infer the
coronal heating mechanism by comparing observations of coronal loops
with hydrodynamic model predictions. These comparisons often used
the addition of sub-resolution strands to explain the observed loop
properties. On July 11, 2012, the High Resolution Coronal Imager (Hi-C)
was launched on a sounding rocket. This instrument obtained images of
the solar corona was 0.2-0.3” resolution in a narrowband EUV filter
centered around 193 Angstroms. In this talk, we will compare these
high resolution images to simultaneous density measurements obtained
with the Extreme Ultraviolet Imaging Spectrograph (EIS) on Hinode to
determine whether the structures observed with Hi-C are resolved.

---------------------------------------------------------
Title: Science Enabled by Advances in UV/EUV Technologies
Authors: Golub, L.
2012AGUFMSA13D..01G Altcode:
The development of EUV multilayer coating technology has permitted
high-quality reflective optics to be constructed for operation at EUV
wavelengths, and the availability of low-cost rapid flight opportunities
has enabled the use of this technology to address major questions in
solar science. We present a brief overview of the way in which the
technology developed and was applied to solar studies and we discuss
some of the significant achievements that have resulted from the use of
this instrumentation in sounding rockets and satellites. We conclude
with a discussion of some new directions for this technology and some
indications of the directions that the work may take.

---------------------------------------------------------
Title: The 2012 Transit of Venus for Cytherean Atmospheric Studies
and as an Exoplanet Analog
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
Reardon, K. P.; Widemann, T.; Tanga, P.; Dantowitz, R.; Willson,
R.; Kopp, G.; Yurchyshyn, V.; Sterling, A.; Scherrer, P.; Schou, J.;
Golub, L.; Reeves, K.
2012DPS....4450806P Altcode:
We worked to assemble as complete a dataset as possible for the
Cytherean atmosphere in collaboration with Venus Express in situ
and to provide an analog of spectral and total irradiance exoplanet
measurements. From Haleakala, the whole transit was visible in
coronal skies; our B images showed the evolution of the visibility
of Venus's atmosphere and of the black-drop effect, as part of the
Venus Twilight Experiment's 9 coronagraphs distributed worldwide
with BVRI. We imaged the Cytherean atmosphere over two minutes before
first contact, with subarcsecond resolution, with the coronagraph and
a separate refractor. The IBIS imaging spectrometer at Sacramento
Peak Observatory at H-alpha and carbon-dioxide also provided us
high-resolution imaging. The NST of Big Bear Solar Observatory
also provided high-resolution vacuum observations of the Cytherean
atmosphere and black drop evolution. Our liaison with UH's Mees Solar
Observatory scientists provided magneto-optical imaging at calcium
and potassium. Spaceborne observations included the Solar Dynamics
Observatory's AIA and HMI, and the Solar Optical Telescope (SOT)
and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance
measurements with ACRIMSAT and SORCE/TIM, to characterize the
event as an exoplanet-transit analog. Our expedition was sponsored
by the Committee for Research and Exploration/National Geographic
Society. Some of the funds for the carbon-dioxide filter for IBIS were
provided by NASA through AAS's Small Research Grant Program. We thank
Rob Lucas, Aram Friedman, and Eric Pilger '82 for assistance with
Haleakala observing, Rob Ratkowski of Haleakala Amateur Astronomers
for assistance with equipment and with the site, Stan Truitt for the
loan of his Paramount ME, and Steve Bisque/Software Bisque for TheSky
X controller. We thank Joseph Gangestad '06 of Aerospace Corp., a
veteran of our 2004 expedition, for assistance at Big Bear. We thank
the Lockheed Martin Solar and Astrophysics Laboratory and Hinode
science and operations teams for planning and support.

---------------------------------------------------------
Title: Design, performance prediction, and measurements of the
interface region imaging spectrograph (IRIS) telescope
Authors: Podgorski, William A.; Cheimets, Peter N.; Golub, Leon;
Lemen, James R.; Title, Alan M.
2012SPIE.8443E..3DP Altcode:
This paper discusses the design of the IRIS Small Explorer
(SMEX) Cassegrain telescope, as well as its intended and measured
performance. Lockheed Martin, along with SAO, Montana State University,
and Stanford University are developing the IRIS instrument for a mission
to examine the solar spectra in two bands, one centered on 1369 Å,
and the other centered on 2810 Å. SAO led the design and construction
of the telescope feed, with assistance from Lockheed and Montana State
University. The telescope posed a number of implementation challenges,
which are discussed here, including the fact that no effective filters
exist to isolate the science spectra to the exclusion of the rest
of the solar flux, making it necessary to allow full sunlight into
the telescope.

---------------------------------------------------------
Title: In-band and out-of-band reflectance calibrations of the EUV
multilayer mirrors of the atmospheric imaging assembly instrument
aboard the Solar Dynamics Observatory
Authors: Soufli, Regina; Spiller, Eberhard; Windt, David L.;
Robinson, Jeff C.; Gullikson, Eric M.; Rodriguez-de Marcos, Luis;
Fernandez-Perea, Monica; Baker, Sherry L.; Aquila, Andrew L.; Dollar,
Franklin J.; Méndez, José Antonio; Larruquert, Juan I.; Golub,
Leon; Boerner, Paul
2012SPIE.8443E..3CS Altcode:
Experimental multilayer reflectance data on flight mirrors and witnesses
for three extreme ultraviolet (EUV) channels of the Atmospheric Imaging
Assembly (AIA) instrument aboard NASA’s Solar Dynamics Observatory
are presented and compared to theoretical models. The relevance of
these results to the performance of the AIA instrument is discussed.

---------------------------------------------------------
Title: The interface region imaging spectrograph for the IRIS Small
Explorer mission
Authors: Wülser, Jean-Pierre; Title, Alan M.; Lemen, James R.; De
Pontieu, Bart; Kankelborg, Charles C.; Tarbell, Theodore D.; Berger,
Thomas E.; Golub, Leon; Kushner, Gary D.; Chou, Catherine Y.; Weingrod,
Isaac; Holmes, Buck; Mudge, Jason; Podgorski, William A.
2012SPIE.8443E..08W Altcode:
The Interface Region Imaging Spectrograph (IRIS) is a NASA SMall
EXplorer mission scheduled for launch in January 2013. The primary goal
of IRIS is to understand how the solar atmosphere is energized. The
IRIS investigation combines advanced numerical modeling with a high
resolution UV imaging spectrograph. IRIS will obtain UV spectra
and images with high resolution in space (0.4 arcsec) and time (1s)
focused on the chromosphere and transition region of the Sun, a complex
interface region between the photosphere and corona. The IRIS instrument
uses a Cassegrain telescope to feed a dual spectrograph and slit-jaw
imager that operate in the 133-141 nm and 278-283 nm ranges. This paper
describes the instrument with emphasis on the imaging spectrograph,
and presents an initial performance assessment from ground test results.

---------------------------------------------------------
Title: Asymmetric Structure of Quiescent Filament Channels Observed
by Hinode/XRT and STEREO/EUVI
Authors: Su, Y.; van Ballegooijen, A.; Golub, L.
2012ASPC..454..113S Altcode: 2012arXiv1208.1529S
We present a study on the structure of quiescent filament channels
observed by Hinode/XRT and STEREO/EUVI from December 2006 to February
2009. For 10 channels identified on the solar disk, we find that the
emission on the two sides of the channel is asymmetric in both X-rays
and EUV: one side has curved bright features while the other side
has straight faint features. We interpret the results in terms of a
magnetic flux rope model. The asymmetry in the emission is due to the
variation in axial magnetic flux along the channel, which causes one
polarity to turn into the flux rope, while the field lines from the
other polarity are open or connected to very distant sources. For 70
channels identified by cavities at the limb, the asymmetry cannot be
clearly identified.

---------------------------------------------------------
Title: Cooler and Hotter X-ray Bright Points from Hinode/XRT
Observations
Authors: Kariyappa, R.; DeLuca, E. E.; Saar, S. H.; Golub, L.; Damé,
L.; Varghese, B. A.
2012ASPC..454..149K Altcode:
We use a 7-hour (17:00 UT - 24:00 UT) time sequence of soft X-ray images
observed almost simultaneously in two filters (Ti_poly and Al_mesh) on
April 14, 2007 with X-Ray Telescope (XRT) on-board the Hinode mission
to determine the temperature of X-ray bright points (XBPs). A sample
of 14 XBPs and 2 background coronal regions have been identified and
selected on both the images for detailed analysis. The temperature of
XBPs is determined by filter ratio method. We find that the XBPs show
temperature fluctuations and that the average temperature ranges from
1.1 MK to 3.4 MK which may correspond to different X-ray fluxes. These
results suggest the existence of cooler and hotter XBPs and that the
heating rate of XBPs is highly variable on short time scales.

---------------------------------------------------------
Title: Prominences observations with SDO/AIA
Authors: Parenti, Susanna; Schmieder, Brigitte; Golub, Leon; Heinzel,
Petr
2012cosp...39.1447P Altcode: 2012cosp.meet.1447P
The Prominence-Corona-Transition-Region (PCTR) plays a key role in
the thermal and pressure equilibrium of prominences. However, several
open issues limit our knowledge of this important interface. Among
them we find the thermal structure and the maximum temperature of
its emitting plasma. This work is a new step toward resolving these
issues. By noting that prominences may be observed in emission in
the 171 and 131 SDO/AIA images, while they are seen in absorption in
others (e.g. 193) we investigate the temperature content of these
channels. Using the CHIANTI atomic database and previously derived
prominence DEMs, we built synthetic spectra in these AIA channels to
establish the main contributors. We find that the Fe IX line always
dominates the 171 band, even in absence of a coronal plasma, while
the 131 channel is dominated by Fe VIII. Our conclusion is that the
PCTR reaches, at least, 4x 10^5 K.

---------------------------------------------------------
Title: On the Nature of Prominence Emission Observed by SDO/AIA
Authors: Parenti, S.; Schmieder, B.; Heinzel, P.; Golub, L.
2012ApJ...754...66P Altcode: 2012arXiv1205.5460P
The prominence-corona transition region (PCTR) plays a key role in the
thermal and pressure equilibrium of solar prominences. Our knowledge
of this interface is limited and several major issues remain open,
including the thermal structure and, in particular, the maximum
temperature of the detectable plasma. The high signal-to-noise
ratio of images obtained by the Atmospheric Imaging Assembly (AIA)
on NASA's Solar Dynamics Observatory clearly shows that prominences
are often seen in emission in the 171 and 131 bands. We investigate the
temperature sensitivity of these AIA bands for prominence observations,
in order to infer the temperature content in an effort to explain the
emission. Using the CHIANTI atomic database and previously determined
prominence differential emission measure distributions, we build
synthetic spectra to establish the main emission-line contributors
in the AIA bands. We find that the Fe IX line always dominates
the 171 band, even in the absence of plasma at &gt;106 K
temperatures, while the 131 band is dominated by Fe VIII. We conclude
that the PCTR has sufficient plasma emitting at &gt;4 × 105
K to be detected by AIA.

---------------------------------------------------------
Title: Plasmoid Ejection at a Solar Total Eclipse
Authors: Koutchmy, S.; Bazin, C.; Berghmans, D.; De Groof, A.;
Druckmüller, M.; Tavabi, E.; Engell, A.; Filippov, B.; Golub, L.;
Lamy, Ph.; Linker, J.; Mikic, Z.; Mouette, J.; Nitschelm, Ch.; Seaton,
D.; Slemzin, V.
2012EAS....55..223K Altcode:
The existence of coronal plasmoids has been postulated for many years
in order to supply material to streamers and possibly to the solar
wind (SW). The W-L SoHO C2 Lasco coronagraph observations were made
under the 2.2 solar radii (R0) occulting disk to look at the ultimate
sources of the SW; EUV imagers are preferably devoted to the analysis
of the corona on and very near the solar disk. Here, in addition to
eclipse white-light (W-L) snapshots, we used the new SWAP space-borne
imager designed for the systematic survey of coronal activity in the
EUV lines near 17.4 nm, over a field of view (FOV) up to 2 R0. Using
summed and co-aligned images, the corona can then be evaluated for the
1st time up to the limit of this FOV. At the time of the July 11, 2010,
solar total eclipse a 20h continuous run of observations was collected,
including images taken during eclipse totality from several ground
observing locations where W-L data were collected. A plasmoid-like
off-limb event was followed using the SWAP summed

---------------------------------------------------------
Title: On the Visibility of Solar Prominences in SDO/AIA Channels
Authors: Heinzel, P.; Schmieder, B.; Parenti, S.; Golub, L.
2012ASPC..456...75H Altcode:
Prominences in EUV lines are observed as dark structures over the
limb due absorption and emission blocking mechanisms. However, at 171
Å is observed emission in prominences with TRACE and SDO/AIA, and
it is believed to be due to the prominence-corona transition region
(PCTR) emitting in cool lines. To check this, we use the Differential
Emission Measure (DEM) recently obtained for quiescent prominences
using SOHO/SUMER spectra (Parenti and Vial 2007) and compute the
synthetic spectra in selected AIA channels. We then compare 171 Å and
195 Å channels and derive conclusions concerning the PCTR emissivity,
as well well as the absorption and blocking. The emission seen in the
171 Å channel can be used to better constrain prominence DEM curves.

---------------------------------------------------------
Title: Temperature Diagnostic of a Brightening Observed by Hinode/XRT
Authors: Dudík, J.; Reeves, K. K.; Schmieder, B.; Dzifčáková,
E.; Golub, L.
2012ASPC..456..137D Altcode:
We analyze the temperature distribution of the active region brightening
observed by HINODE/XRT. The temperature structure is derived using
various filter-ratio techniques and DEM analysis. The results are
compared and it is found that the filter-ratio techniques are accurate
only for relatively narrow DEMs.

---------------------------------------------------------
Title: Hot Plasma Detected in Active Regions by HINODE/XRT and SDO/AIA
Authors: Reale, F.; Testa, P.; Guarrasi, M.; DeLuca, E.; Peres, G.;
Golub, L.
2012ASPC..456..129R Altcode:
Multiple ratios of Hinode/XRT filters showed evidence of a minor
very hot emission measure component in active regions. Recently also
SDO/AIA detected hot plasma in the core of an active region. Here
we provide estimates showing that the amount of emission measure of
the hot component detected with SDO is consistent with that detected
with Hinode/XRT.

---------------------------------------------------------
Title: The Fifth Hinode Science Meeting
Authors: Golub, L.; De Moortel, I.; Shimizu, T.
2012ASPC..456.....G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Differential Emission Measure Analysis for AIA and XRT
Observations of Comet Lovejoy (C/2011 W3)
Authors: McCauley, Patrick; Saar, S. H.; Raymond, J.; Golub, L. E.
2012AAS...22020115M Altcode:
We present observations of Comet Lovejoy (C/2011 W3) recorded by
the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics
Observatory (SDO) and the X-Ray Telescope (XRT) aboard the Hinode
satellite. Lovejoy, a member of the Kreutz family of sungrazing comets,
came to within 1.2 solar radii during its perihelion approach and
escaped, despite expectations to the contrary, on December 6, 2011. The
most significant sungrazer since the launch of SDO, Lovejoy provides an
unprecedented opportunity to examine the effects of a comet traversing
the solar corona. Both the ingress and egress were detected in seven
AIA passbands (131, 171, 193, 211, 304, 335, and 1600 Angstroms),
with XRT successfully imaging the outbound trip using its Al-mesh
filter. We estimate the temperature structure of the emitting plasma
using a differential emission measure analysis and explore interactions
with the solar magnetic field. In several cases, secondary lines in a
given channel appear to be the dominant comet-related emitters. Use of
a radial filter for improved contrast of the faint cometary emission
is also discussed.

---------------------------------------------------------
Title: Defining the "Blind Spot" of Hinode EIS and XRT Temperature
Measurements
Authors: Winebarger, Amy R.; Warren, Harry P.; Schmelz, Joan T.;
Cirtain, Jonathan; Mulu-Moore, Fana; Golub, Leon; Kobayashi, Ken
2012ApJ...746L..17W Altcode:
Observing high-temperature, low emission measure plasma is key to
unlocking the coronal heating problem. With current instrumentation,
a combination of EUV spectral data from Hinode Extreme-ultraviolet
Imaging Spectrometer (EIS; sensitive to temperatures up to 4 MK)
and broadband filter data from Hinode X-ray Telescope (XRT; sensitive
to higher temperatures) is typically used to diagnose the temperature
structure of the observed plasma. In this Letter, we demonstrate that a
"blind spot" exists in temperature-emission measure space for combined
Hinode EIS and XRT observations. For a typical active region core with
significant emission at 3-4 MK, Hinode EIS and XRT are insensitive
to plasma with temperatures greater than ~6 MK and emission measures
less than ~1027 cm-5. We then demonstrate that
the temperature and emission measure limits of this blind spot depend
upon the temperature distribution of the plasma along the line of sight
by considering a hypothetical emission measure distribution sharply
peaked at 1 MK. For this emission measure distribution, we find that
EIS and XRT are insensitive to plasma with emission measures less
than ~1026 cm-5. We suggest that a spatially and
spectrally resolved 6-24 Å spectrum would improve the sensitivity to
these high-temperature, low emission measure plasma.

---------------------------------------------------------
Title: The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics
Observatory (SDO)
Authors: Lemen, James R.; Title, Alan M.; Akin, David J.; Boerner,
Paul F.; Chou, Catherine; Drake, Jerry F.; Duncan, Dexter W.; Edwards,
Christopher G.; Friedlaender, Frank M.; Heyman, Gary F.; Hurlburt, Neal
E.; Katz, Noah L.; Kushner, Gary D.; Levay, Michael; Lindgren, Russell
W.; Mathur, Dnyanesh P.; McFeaters, Edward L.; Mitchell, Sarah; Rehse,
Roger A.; Schrijver, Carolus J.; Springer, Larry A.; Stern, Robert A.;
Tarbell, Theodore D.; Wuelser, Jean-Pierre; Wolfson, C. Jacob; Yanari,
Carl; Bookbinder, Jay A.; Cheimets, Peter N.; Caldwell, David; Deluca,
Edward E.; Gates, Richard; Golub, Leon; Park, Sang; Podgorski, William
A.; Bush, Rock I.; Scherrer, Philip H.; Gummin, Mark A.; Smith, Peter;
Auker, Gary; Jerram, Paul; Pool, Peter; Soufli, Regina; Windt, David
L.; Beardsley, Sarah; Clapp, Matthew; Lang, James; Waltham, Nicholas
2012SoPh..275...17L Altcode: 2011SoPh..tmp..106L; 2011SoPh..tmp..172L; 2011SoPh..tmp..241L;
2011SoPh..tmp..115L
The Atmospheric Imaging Assembly (AIA) provides multiple simultaneous
high-resolution full-disk images of the corona and transition region
up to 0.5 R⊙ above the solar limb with 1.5-arcsec spatial
resolution and 12-second temporal resolution. The AIA consists of four
telescopes that employ normal-incidence, multilayer-coated optics to
provide narrow-band imaging of seven extreme ultraviolet (EUV) band
passes centered on specific lines: Fe XVIII (94 Å), Fe XVII, XXI
(131 Å), Fe IX (171 Å), Fe XII, XXIV (193 Å), Fe XIV (211 Å),
He II (304 Å), and Fe XVI (335 Å). One telescope observes C IV
(near 1600 Å) and the nearby continuum (1700 Å) and has a filter
that observes in the visible to enable coalignment with images from
other telescopes. The temperature diagnostics of the EUV emissions
cover the range from 6×104 K to 2×107 K. The
AIA was launched as a part of NASA's Solar Dynamics Observatory (SDO)
mission on 11 February 2010. AIA will advance our understanding of the
mechanisms of solar variability and of how the Sun's energy is stored
and released into the heliosphere and geospace.

---------------------------------------------------------
Title: Initial Calibration of the Atmospheric Imaging Assembly (AIA)
on the Solar Dynamics Observatory (SDO)
Authors: Boerner, Paul; Edwards, Christopher; Lemen, James; Rausch,
Adam; Schrijver, Carolus; Shine, Richard; Shing, Lawrence; Stern,
Robert; Tarbell, Theodore; Title, Alan; Wolfson, C. Jacob; Soufli,
Regina; Spiller, Eberhard; Gullikson, Eric; McKenzie, David; Windt,
David; Golub, Leon; Podgorski, William; Testa, Paola; Weber, Mark
2012SoPh..275...41B Altcode:
The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar
Dynamics Observatory (SDO) is an array of four normal-incidence
reflecting telescopes that image the Sun in ten EUV and UV wavelength
channels. We present the initial photometric calibration of AIA,
based on preflight measurements of the response of the telescope
components. The estimated accuracy is of order 25%, which is consistent
with the results of comparisons with full-disk irradiance measurements
and spectral models. We also describe the characterization of the
instrument performance, including image resolution, alignment,
camera-system gain, flat-fielding, and data compression.

---------------------------------------------------------
Title: Observations and Interpretation of a Low Coronal Shock Wave
Observed in the EUV by the SDO/AIA
Authors: Ma, Suli; Raymond, John C.; Golub, Leon; Lin, Jun; Chen,
Huadong; Grigis, Paolo; Testa, Paola; Long, David
2011ApJ...738..160M Altcode: 2011arXiv1106.6056M
Taking advantage of both the high temporal and spatial resolutions
of the Atmospheric Imaging Assembly on board the Solar Dynamics
Observatory, we studied a limb coronal shock wave and its associated
extreme ultraviolet (EUV) wave that occurred on 2010 June 13. Our main
findings are: (1) the shock wave appeared clearly only in the channels
centered at 193 Å and 211 Å as a dome-like enhancement propagating
ahead of its associated semi-spherical coronal mass ejection (CME)
bubble; (2) the density compression of the shock is 1.56 according
to radio data and the temperature of the shock is around 2.8 MK
(3) the shock wave first appeared at 05:38 UT, 2 minutes after the
associated flare has started and 1 minute after its associated CME
bubble appeared; (4) the top of the dome-like shock wave set out
from about 1.23 R sun and the thickness of the shocked
layer is ~2 × 104 km (5) the speed of the shock wave is
consistent with a slight decrease from about 600 km s-1
to 550 km s-1 and (6) the lateral expansion of the shock
wave suggests a constant speed around 400 km s-1, which
varies at different heights and directions. Our findings support the
view that the coronal shock wave is driven by the CME bubble, and the
on-limb EUV wave is consistent with a fast wave or at least includes
the fast wave component.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS)
Authors: Kobayashi, Ken; Cirtain, Jonathan; Golub, Leon; Winebarger,
Amy; Hertz, Edward; Cheimets, Peter; Caldwell, David; Korreck, Kelly;
Robinson, Brian; Reardon, Patrick; Kester, Thomas; Griffith, Charles;
Young, Mark
2011SPIE.8147E..1MK Altcode: 2011SPIE.8147E..54K
The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) is a proposed
sounding rocket experiment designed to observe spatially resolved soft
X-ray spectra of the solar corona for the first time. The instrument is
a purely grazing-incidence design, consisting of aWolter Type-1 sector
telescope and a slit spectrograph. The telescope mirror is a monolithic
Zerodur mirror with both the parabolic and hyperbolic surfaces. The
spectrograph comprises a pair of paraboloid mirrors acting as a
collimator and reimaging mirror, and a planar varied-line-space grating,
with reflective surfaces operate at a graze angle of 2 degrees. This
produces a flat spectrum on a detector covering a wavelength range of
6-24Å (0.5-1.2 keV). The design achieves 20 mÅ spectral resolution
(10 mÅ /pixel) and 5 arcsec spatial resolution (2.5 arcsec / pixel)
over an 8-arcminute long slit. The spectrograph is currently being
fabricated as a laboratory prototype. A flight candidate telescope
mirror is also under development.

---------------------------------------------------------
Title: Solar Dynamics Observatory Discovers Thin High Temperature
Strands in Coronal Active Regions
Authors: Reale, Fabio; Guarrasi, Massimiliano; Testa, Paola; DeLuca,
Edward E.; Peres, Giovanni; Golub, Leon
2011ApJ...736L..16R Altcode: 2011arXiv1106.1591R
One scenario proposed to explain the million degree solar corona
is a finely stranded corona where each strand is heated by a rapid
pulse. However, such fine structure has neither been resolved through
direct imaging observations nor conclusively shown through indirect
observations of extended superhot plasma. Recently, it has been shown
that the observed difference in the appearance of cool and warm coronal
loops (~1 MK and ~2-3 MK, respectively)—warm loops appearing "fuzzier"
than cool loops—can be explained by models of loops composed of
subarcsecond strands, which are impulsively heated up to ~10 MK. That
work predicts that images of hot coronal loops (gsim 6 MK) should
again show fine structure. Here we show that the predicted effect is
indeed widely observed in an active region with the Solar Dynamics
Observatory, thus supporting a scenario where impulsive heating of
fine loop strands plays an important role in powering the active corona.

---------------------------------------------------------
Title: Structure and Dynamics of the 2010 July 11 Eclipse White-light
Corona
Authors: Pasachoff, J. M.; Rušin, V.; Druckmüllerová, H.; Saniga,
M.; Lu, M.; Malamut, C.; Seaton, D. B.; Golub, L.; Engell, A. J.;
Hill, S. W.; Lucas, R.
2011ApJ...734..114P Altcode:
The white-light corona (WLC) during the total solar eclipse on 2010
July 11 was observed by several teams in the Moon's shadow stretching
across the Pacific Ocean and a number of isolated islands. We present
a comparison of the WLC as observed by eclipse teams located on the
Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes
later, combined with near-simultaneous space observations. The eclipse
was observed at the beginning of the solar cycle, not long after solar
minimum. Nevertheless, the solar corona shows a plethora of different
features (coronal holes, helmet streamers, polar rays, very faint
loops and radial-oriented thin streamers, a coronal mass ejection,
and a puzzling "curtain-like" object above the north pole). Comparing
the observations from the two sites enables us to detect some dynamic
phenomena. The eclipse observations are further compared with a
hairy-ball model of the magnetic field and near-simultaneous images from
the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory,
the Extreme Ultraviolet Imager on NASA's Solar Terrestrial Relations
Observatory, the Sun Watcher, using Active Pixel System Detector and
Image Processing on ESA's PRoject for Onboard Autonomy, and the Naval
Research Laboratory's Large Angle and Spectrometric Coronagraph on
ESA's Solar and Heliospheric Observatory. The Ludendorff flattening
coefficient is 0.156, matching the expected ellipticity of coronal
isophotes at 2 R sun, for this rising phase of the
solar-activity cycle.

---------------------------------------------------------
Title: Observations and Magnetic Field Modeling of the Flare/coronal
Mass Ejection Event on 2010 April 8
Authors: Su, Yingna; Surges, Vincent; van Ballegooijen, Adriaan;
DeLuca, Edward; Golub, Leon
2011ApJ...734...53S Altcode:
We present a study of the flare/coronal mass ejection event that
occurred in Active Region 11060 on 2010 April 8. This event also
involves a filament eruption, EIT wave, and coronal dimming. Prior to
the flare onset and filament eruption, both SDO/AIA and STEREO/EUVI
observe a nearly horizontal filament ejection along the internal
polarity inversion line, where flux cancellations frequently occur as
observed by SDO/HMI. Using the flux-rope insertion method developed
by van Ballegooijen, we construct a grid of magnetic field models
using two magneto-frictional relaxation methods. We find that the
poloidal flux is significantly reduced during the relaxation process,
though one relaxation method preserves the poloidal flux better
than the other. The best-fit pre-flare NLFFF model is constrained by
matching the coronal loops observed by SDO/AIA and Hinode/XRT. We find
that the axial flux in this model is very close to the threshold of
instability. For the model that becomes unstable due to an increase of
the axial flux, the reconnected field lines below the X-point closely
match the observed highly sheared flare loops at the event onset. The
footpoints of the erupting flux rope are located around the coronal
dimming regions. Both observational and modeling results support
the premise that this event may be initiated by catastrophic loss of
equilibrium caused by an increase of the axial flux in the flux rope,
which is driven by flux cancellations.

---------------------------------------------------------
Title: High-resolution EUV imaging of the solar corona in the
ARKA project
Authors: Shestov, S.; Bogachev, S.; Kuzin, S.; Golub, L.
2011simi.conf...39S Altcode:
ARKA – is a new space-borne mission, being developed in cooperation
by Lavochkin Science and Production Association (Russia), Lebedev
Physical Institute (Russia) and Smithsonian Astrophysical Laboratory
(USA), to be launched in 2018. The main goal of the ARKA project – EUV
observation of the solar corona with unprecedented spatial resolution
of 0.15 arc.sec./pixel. Such a high resolution will be achieved by
using Richey-Chr tien optical schema with F=15 m and large-area 4k x 4k
CCD detectors. The instrument promises as significant improvement in
resolution over AIA and TRACE as that achieved in going from SOHO/EIT
instrument to the TRACE telescope, with consequent likelihood of
dramatic advances in our understanding of coronal dynamics. The
key scientific goals of these hi-res observations are the following:
observations of small-scale magnetic filed in the corona and its role in
the heating of coronal plasma, diagnostics of coronal and chromospheric
plasma using MHD seismology, observations of when and how 3D magnetic
reconnection occurs in flaring active regions, characterization
the triggering and initial development of the CMEs. The ARKA
instrumentation is planned to be launched on a KARAT statellite,
on the 5th satellite of the Russian small-satellite program. The
instrumentation will include 2 high-resolution F=15 m telescopes,
one developed by SAO for 193 and one by LPI for 304 spectral range, a
full-Sun context imager for 171 and high-energy full-Sun telescope for
the 5-100 keV. The two latter instruments will considerably supplement
hi-resolution EUV telescopes, allowing full-Sun monitoring of flares
and CMEs.

---------------------------------------------------------
Title: Dynamics of Coronal Mass Ejection Origins
Authors: Ma, Suli; Lin, J.; Golub, L.
2011SPD....42.1304M Altcode: 2011BAAS..43S.1304M
Coronal mass ejections (CMEs) are massive eruptions of magnetised plasma
that is believed to be originated from the solar corona. CMEs are known
to play a significant role in driving disastrous space weather. This
thesis focuses on understanding the dynamics of CMEs source regions
with the observations made by STEREO, the Solar Terrestrial Relations
Observatory. The successful launch of STEREO provides us with
the first-ever stereoscopic measurements to study the 3D structures
of CMEs. With the data from Extreme Ultra-Violet Imager (EUVI) and
coronagraphs COR1 and COR2 onboard both STEREO Ahead (A) and STEREO
Behind (B) and the data from other instruments, we studied of the
initiation of a CME and its associated phenomena. The CME occurs on
2007 December 7, during which the separation angle of STEREO A with
B is about 42.4°. This offers us a good opportunity to study the
initiation of the CME stereoscopically. Using the data from both
STEREO A and B, we made a detailed comparison for the morphologies
and kinematics of its associated "EIT wave". The results indicate
that the nascent CME seems to affect the morphology of the EIT wave,
vise verse, i.e., the morphology of EIT wave reflects the morphology of
the CME. Taking the advantage of the two viewpoints of the STEREO
spacecrafts from January 1 to August 31, 2009, we identified 34 CMEs
that originated from almost one quarter of the Sun which faces the
Earth. It is found that about 33% of them had no distinct low coronal
signature (such as coronal dimming, coronal wave, filament eruption,
post-eruptive arcade). It might be a new challenge for our present
models of CME origination.

---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS) NASA SMEX
Authors: Lemen, James; Title, A.; De Pontieu, B.; Schrijver, C.;
Tarbell, T.; Wuelser, J.; Golub, L.; Kankelborg, C.
2011SPD....42.1512L Altcode: 2011BAAS..43S.1512L
The solar chromosphere and transition region (TR) is highly structured,
dynamic, and intimately connected to the corona. It requires more
than ten times the energy required to heat the corona, and yet it
has received far less interest because of the complexity of the
required observational and analytical tools. In the TR the density
drops by six orders of magnitude and the temperature increases by
three orders of magnitude. Hinode observations reveal the importance
the magnetic field has on this region of the solar atmosphere that
acts as the interface between the photosphere and the corona. The
Interface Region Imaging Spectrograph (IRIS) was selected for a NASA
SMEX mission in 2009 and is scheduled to launch in December 2012. IRIS
addresses critical questions in order to understand the flow of energy
and mass through the chromosphere and TR, namely: (1) Which types of
non-thermal energy dominate in the chromosphere and beyond? (2) How
does the chromosphere regulate mass and energy supply to the corona
and heliosphere? (3) How do magnetic flux and matter rise through the
lower atmosphere, and what roles dos flux emergence play in flares and
mass ejections? These questions are addressed with a high-resolution
imaging spectrometer that observes Near- and Far-VU emissions that
are formed at temperatures between 5,000K and 1.5 x 106
K. IRIS has a field-of-view of 120 arcsec, a spatial resolution
of 0.4 arcsec, and velocity resolution of 0.5 km/s. Members of the
IRIS investigation team are developing advanced radiative MHD codes
to facilitate comparison with and interpretation of observations. We
present the status of the IRIS observatory development, which completed
its Critical Design Review in December 2010.

---------------------------------------------------------
Title: The Solar Corona and a CME at the 2010 Total Eclipse
Authors: Pasachoff, Jay M.; Rusin, V.; Druckmüllerová, H.; Saniga,
M.; Lu, M.; Malamut, C.; Seaton, D. B.; Golub, L.; Engell, A. J.;
Hill, S. W.; Lucas, R.
2011SPD....42.1813P Altcode: 2011BAAS..43S.1813P
The 11 July 2010 total solar eclipse was observed on the ground
from French Polynesia and, 83 minutes later, from Easter Island, and
near-simultaneous images were made with spacecraft instruments including
AIA/SDO, HMI/SDO, EUVI/STEREO, SWAP/PROBA2, EIT/SOHO, and LASCO/SOHO. We
report on changes in the corona detectable with high-resolution image
processing of the ground-based eclipse coronal imaging, including
two CME's that were seen to evolve. We compare with the spacecraft
images to give a complete depiction of coronal structure at the time
of the eclipse, which corresponded to a low but rising phase of the
solar-activity cycle. We acknowledge the support of NASA's MSFC
NNX10AK47A, NSF REU AST-1005024 with DoD ASSURE, VEGA 2/0098/10 of the
Slovak Acad. Sci, 205/09/1469 of the Czech Science Foundation, PRODEX
C90345 of ESA/BELSPO, FP7/2007-2013/218816 SOTERIA, Lockheed Martin;
for equipment: Nikon Professional Services, ASTELCO Systems GmbH
(Germany), and National Geographic Society's Photographic Division;
and colleagues Y.-M. Wang (NRL), S. Habbal (U. Hawaii), H. Lanteires
(Tatakoto), and J. Kern (Carnegie Obs.).

---------------------------------------------------------
Title: Comparison Of Simulated And Observed Loop-top Emission In
Flares Using The AIA Telescopes On SDO
Authors: Reeves, Kathy; Engell, A.; Ji, L.; Smith, R.; Golub, L.
2011SPD....42.2122R Altcode: 2011BAAS..43S.2122R
We investigate the temporal behavior of loop-top emission in
flaring loops observed by AIA's six EUV passbands for several
flares of different sizes. These flares are chosen because they
exhibit extended periods of loop-top emission in the 193 A channel,
thought to be hot emission from Fe XXIV. The flare light curves from
this loop-top emission clearly show the progression of flare cooling
through the various ionization states of iron that dominate the AIA
bands. We use the model of Reeves, Warren &amp; Forbes (2007), which
predicts extended periods of loop-top flare emission, to model the
flare loop energization, and explore the effects of different energy
release rates and durations on the simulated flare light curves. We
also explore the conditions under which non-equilibrium ionization
effects may be important in these events.

---------------------------------------------------------
Title: Coronal-Temperature-Diagnostic Capability of the Hinode/
X-Ray Telescope Based on Self-Consistent Calibration
Authors: Narukage, N.; Sakao, T.; Kano, R.; Hara, H.; Shimojo, M.;
Bando, T.; Urayama, F.; DeLuca, E.; Golub, L.; Weber, M.; Grigis,
P.; Cirtain, J.; Tsuneta, S.
2011SoPh..269..169N Altcode: 2010arXiv1011.2867N; 2011SoPh..tmp....1N
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray
imager that observes the solar corona with unprecedentedly high angular
resolution (consistent with its 1″ pixel size). XRT has nine X-ray
analysis filters with different temperature responses. One of the most
significant scientific features of this telescope is its capability
of diagnosing coronal temperatures from less than 1 MK to more than
10 MK, which has never been accomplished before. To make full use
of this capability, accurate calibration of the coronal temperature
response of XRT is indispensable and is presented in this article. The
effect of on-orbit contamination is also taken into account in the
calibration. On the basis of our calibration results, we review the
coronal-temperature-diagnostic capability of XRT.

---------------------------------------------------------
Title: Temperature variability in X-ray bright points observed
with Hinode/XRT
Authors: Kariyappa, R.; Deluca, E. E.; Saar, S. H.; Golub, L.; Damé,
L.; Pevtsov, A. A.; Varghese, B. A.
2011A&A...526A..78K Altcode:
 Aims: We investigate the variability in temperature as
a function of time among a sample of coronal X-ray bright points
(XBPs). Methods: We analysed a 7-h (17:00-24:00 UT) long time
sequence of soft X-ray images observed almost simultaneously in two
filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope
(XRT) onboard the Hinode mission. We identified and selected 14 XBPs
for a detailed analysis. The light curves of XBPs were derived using
the SolarSoft library in IDL. The temperature of XBPs was determined
using the calibrated temperature response curves of the two filters
by means of the intensity ratio method. Results: We find that
the XBPs show a high variability in their temperature and that the
average temperature ranges from 1.1 MK to 3.4 MK. The variations
in temperature are often correlated with changes in average X-ray
emission. It is evident from the results of time series that the XBP
heating rate can be highly variable on short timescales, suggesting
that it has a reconnection origin.

---------------------------------------------------------
Title: Atmospheric Imaging Assembly Observations of Hot Flare Plasma
Authors: Reeves, Katharine K.; Golub, Leon
2011ApJ...727L..52R Altcode:
We present observations of hot plasma from solar eruptions recorded
by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics
Observatory. AIA is the first narrowband instrument capable of taking
images of hot plasma in the 5-15 MK range. We find that there are
hot structures above flare loops, and that they are typically more
diffuse and nebulous than the well-defined flare loops. Because of the
narrowband response, high sensitivity, and high spatial resolution of
AIA, these supra-arcade structures are visible in exquisite detail,
particularly in the 131 Å and 94 Å channels. In one event, a C4.9
flare observed on 2010 November 3, hot plasma is seen to outline an
erupting plasmoid and possibly a current sheet. We compare hot plasma
observed with AIA to structures observed with the X-Ray Telescope on
the Hinode mission and find that the plasma imaged in AIA contains
more fine detail. These new AIA observations show that supra-arcade
flare structures and coronal mass ejections are highly structured
not only in space and time, but also in temperature. This thermal
structuring is expected, based on modeling efforts, but has now been
imaged directly for the first time over a large range of temperatures.

---------------------------------------------------------
Title: Flares and Their Underlying Magnetic Complexity
Authors: Engell, Alexander J.; Siarkowski, Marek; Gryciuk, Magda;
Sylwester, Janusz; Sylwester, Barbara; Golub, Leon; Korreck, Kelly;
Cirtain, Jonathan
2011ApJ...726...12E Altcode:
SphinX (Solar PHotometer IN X-rays), a full-disk-integrated
spectrometer, observed 137 flare-like/transient events with active
region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope
(XRT) and Solar Optical Telescope observe 67 of these events and
identified their location from 12:00 UT on July 3 through 24:00 UT 2009
July 7. We find that the predominant mechanisms for flares observed
by XRT are (1) flux cancellation and (2) the shearing of underlying
magnetic elements. Point- and cusp-like flare morphologies seen by XRT
all occur in a magnetic environment where one polarity is impeded by
the opposite polarity and vice versa, forcing the flux cancellation
process. The shearing is either caused by flux emergence at the
center of the AR and separation of polarities along a neutral line
or by individual magnetic elements having a rotational motion. Both
mechanisms are observed to contribute to single- and multiple-loop
flares. We observe that most loop flares occur along a large portion
of a polarity inversion line. Point- and cusp-like flares become
more infrequent as the AR becomes organized with separation of the
positive and negative polarities. SphinX, which allows us to identify
when these flares occur, provides us with a statistically significant
temperature and emission scaling law for A and B class flares: EM =
6.1 × 1033 T 1.9±0.1.

---------------------------------------------------------
Title: Comparison of simulated and observed loop-top emission in
flares using the AIA telescopes on SDO
Authors: Engell, A.; Reeves, K. K.; Ji, L.; Deluca, E. E.; Smith,
R.; Golub, L.
2010AGUFMSH11A1596E Altcode:
We investigate the spatial and temporal behavior of emission in
flaring loops observed by AIA's 193 (Fe XXIV/XII), 131(Fe XX), 094
(Fe XVIII), 335 (Fe XVI), 211 (Fe XIV), and 171 (Fe IX) channels for
two C class flares and one M class flare. Plotting light curves from
loop-top areas in the six channels reveals the temporal distributions
as a function of the ionization stages, with the same characteristic
behavior identifiable in all three flares. The order of appearance
is from the highest ionization state (FeXXIV) to the lowest (Fe XVI),
and the observations are compared with the Reeves, Warren &amp; Forbes
(2007) model of flare loop energization, calculated for the various
AIA channels. We also model the effects of non-equilibrium ionization
on the simulated light curves.

---------------------------------------------------------
Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Golub, L.; Cirtain, J. W.; Kobayashi, K.; Winebarger, A. R.;
Korreck, K. E.; Testa, P.
2010AGUFMSH11B1631G Altcode:
We present a novel design for a stigmatic grazing incidence X-ray
spectrograph for flight on a NASA sounding rocket. MaGIXS is comprised
of a Wolter I telescope, a slit, a pair of parabolic mirrors, a plano
variable line-spaced grating and a CCD detector. This design and layout
have been optimized to produce an optical system with peak effective
area of 5 mm^2, a wavelength range of 0.6-2.4 nm, spectral resolution of
2.0 pm, and spatial pixels of 2.5 arcsec along a 5 arcminute slit. The
resulting instrument will resolve the solar spectrum for features in
the solar corona with a two orders of magnitude increase over previous
soft x-ray spectrographs in spatial and spectral resolution.

---------------------------------------------------------
Title: Multi-stranded and Multi-thermal Solar Coronal Loops: Evidence
from Hinode X-ray Telescope and EUV Imaging Spectrometer Data
Authors: Schmelz, J. T.; Saar, S. H.; Nasraoui, K.; Kashyap, V. L.;
Weber, M. A.; DeLuca, E. E.; Golub, L.
2010ApJ...723.1180S Altcode:
Data from the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer
(EIS) on the Japanese/USA/UK Hinode spacecraft were used to investigate
the spatial and thermal properties of an isolated quiescent coronal
loop. We constructed differential emission measure (DEM) curves
using Monte Carlo based, iterative forward fitting algorithms. We
studied the loop as a whole, in segments, in transverse cuts, and
point-by-point, always with some form of background subtraction, and
find that the loop DEM is neither isothermal nor extremely broad, with
approximately 96% of the EM between 6.2 &lt;=log T&lt;= 6.7, and an
EM-weighted temperature of log T = 6.48 ± 0.16. We find evidence for
a gradual change in temperature along the loop, with log T increasing
only by ≈0.1 from the footpoints to the peak. The combine XRT-EIS
data set does a good job of constraining the temperature distribution
for coronal loop plasma. Our studies show that the strong constraints
at high and low temperatures provided by the combined data set are
crucial for obtaining reasonable solutions. These results confirm
that the observations of at least some loops are not consistent with
isothermal plasma, and therefore cannot be modeled with a single flux
tube and must be multi-stranded.

---------------------------------------------------------
Title: The Role of Magnetic Topology in the Heating of Active Region
Coronal Loops
Authors: Lee, J. -Y.; Barnes, Graham; Leka, K. D.; Reeves, Katharine
K.; Korreck, K. E.; Golub, L.; DeLuca, E. E.
2010ApJ...723.1493L Altcode: 2010arXiv1009.2070L
We investigate the evolution of coronal loop emission in the context
of the coronal magnetic field topology. New modeling techniques allow
us to investigate the magnetic field structure and energy release
in active regions (ARs). Using these models and high-resolution
multi-wavelength coronal observations from the Transition Region and
Coronal Explorer and the X-ray Telescope on Hinode, we are able to
establish a relationship between the light curves of coronal loops
and their associated magnetic topologies for NOAA AR 10963. We examine
loops that show both transient and steady emission, and we find that
loops that show many transient brightenings are located in domains
associated with a high number of separators. This topology provides
an environment for continual impulsive heating events through magnetic
reconnection at the separators. A loop with relatively constant X-ray
and EUV emission, on the other hand, is located in domains that are
not associated with separators. This result implies that larger-scale
magnetic field reconnections are not involved in heating plasma in
these regions, and the heating in these loops must come from another
mechanism, such as small-scale reconnections (i.e., nanoflares) or
wave heating. Additionally, we find that loops that undergo repeated
transient brightenings are associated with separators that have enhanced
free energy. In contrast, we find one case of an isolated transient
brightening that seems to be associated with separators with a smaller
free energy.

---------------------------------------------------------
Title: Statistical Study of Coronal Mass Ejections With and Without
Distinct Low Coronal Signatures
Authors: Ma, S.; Attrill, G. D. R.; Golub, L.; Lin, J.
2010ApJ...722..289M Altcode:
Taking advantage of the two viewpoints of the STEREO spacecraft,
we present a statistical study of coronal mass ejections (CMEs) with
and without distinct low coronal signatures (LCSs) from 2009 January
1 to August 31. During this period, the lines of sight from STEREO
A and B are almost perpendicular and nearly a quarter of the Sun was
observed by both. We identified 34 CMEs that originated from around
this area and find that (1) about 1 out of 3 CMEs that were studied
during 8 months of solar minimum activity are stealth CMEs; a CME is
stealth if no distinct LCS (such as coronal dimming, coronal wave,
filament eruption, flare, post-eruptive arcade) can be found on the
disk. (2) The speeds of the stealth CMEs without LCSs are typically
below 300 km s-1. Comparing with the slow CMEs with LCSs, the
stealth CMEs did not show any clear differences in their velocity and
acceleration evolution. (3) The source regions of the stealth CMEs are
usually located in the quiet Sun rather than active regions. Detailed
study indicates that more than half of the stealth CMEs in this paper
showed some faint change of the coronal structures (likely parts of
flux ropes) when they could be observed over the solar limb before or
during the CME evolution. Finally, we note that space weather detection
systems based on LCSs totally independent of coronagraph data may fail
to detect a significant proportion of CMEs.

---------------------------------------------------------
Title: Structure and Dynamics of Quiescent Filament Channels Observed
by Hinode/XRT and STEREO/EUVI
Authors: Su, Yingna; van Ballegooijen, Adriaan; Golub, Leon
2010ApJ...721..901S Altcode:
We present a study of the structure and dynamics of quiescent filament
channels observed by Hinode/XRT and STEREO/EUVI at the solar minimum
23/24 from 2006 November to 2008 December. For 12 channels identified on
the solar disk (Group I channels), we find that the morphology of the
structure on the two sides of the channel is asymmetric in both X-rays
and EUV: the eastern side has curved features while the western side has
straight features. We interpret the results in terms of a magnetic flux
rope model. The asymmetry in the morphology is due to the variation in
axial flux of the flux rope along the channel, which causes the field
lines from one polarity to turn into the flux rope (curved feature),
while the field lines from the other polarity are connected to very
distant sources (straight). For most of the 68 channels identified by
cavities at the east and west limbs (Group II channels), the asymmetry
cannot be clearly identified, which is likely due to the fact that the
axial flux may be relatively constant along such channels. Corresponding
cavities are identified only for 5 of the 12 Group I channels, while
Group II channels are identified for all of the 68 cavity pairs. The
studied filament channels are often observed as dark channels in
X-rays and EUV. Sheared loops within Group I channels are often seen
in X-rays, but are rarely seen in Group II channels as shown in the
X-ray Telescope daily synoptic observations. A survey of the dynamics
of studied filament channels shows that filament eruptions occur at an
average rate of 1.4 filament eruptions per channel per solar rotation.

---------------------------------------------------------
Title: Structure and Dynamics of Quiescent Filament Channels Observed
by Hinode/XRT and STEREO/EUVI
Authors: Su, Yingna; van Ballegooijen, Adriaan; Golub, Leon
2010shin.confE..83S Altcode:
We present a study on the structure and dynamics of quiescent filament
channels observed by Hinode/XRT and STEREO/EUVI at the solar minimum
23/24 from December 2006 to December 2008. For 12 channels identified
on the solar disk (Group I channels), we find that the emission on
the two sides of the channel is asymmetric in both X-rays and EUV:
eastern side has curved features while the western side has straight
features. We interpret the results in terms of a magnetic flux rope
model. The asymmetry in the emission is due to the variation in axial
magnetic flux along the channel, which causes the field lines from one
polarity to turn into the flux rope, while the field lines from the
other polarity are connected to very distant sources. For 67 channels
identified by cavities at the east and west limbs (Group II channels),
the asymmetry cannot be clearly identified, which is likely due to the
fact that these channels are nearly parallel to the equator and the
axial flux may be relatively constant along such channels. Corresponding
cavities are identified only for 5 of the 12 Group I channels, while
Group II channels are identified for all of the 68 cavity pairs. The
studied filament channels are often observed as dark channels in
X-rays and EUV. Sheared loops within Group I channels are often seen
in X-rays, but are rarely seen in Group II channels as shown in the
XRT daily synoptic observations. A survey on the dynamics of studied
filament channels shows that filament eruptions occur at an average
rate of 1.4 filament eruptions per channel per solar rotation.

---------------------------------------------------------
Title: Flare Energy Build-Up in a Decaying Active Region Near a
Coronal Hole
Authors: Su, Yingna; van Ballegooijen, Adriaan; Schmieder, Brigitte;
Berlicki, Arkadiusz; Guo, Yang; Golub, Leon; Huang, Guangli
2010shin.confE.131S Altcode:
A B1.7 two-ribbon flare occurred in a highly non-potential decaying
active region near a coronal hole at 10:00 UT on May 17, 2008. This
flare is large in the sense that it involves the entire region, and
it is associated with both a filament eruption and a CME. We present
multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays
(Hinode/XRT), and H-alpha (THEMIS, BBSO) prior to, during and after
the flare. Prior to the flare, the region contained two filaments. The
long J-shaped sheared loops corresponding to the southern filament
were evolved from two short loop systems, which happened around 22:00
UT after a filament eruption on May 16. Formation of highly sheared
loops in the south eastern part of the region was observed by STEREO
8 hours before the flare. We also perform non-linear force free field
(NLFFF) modeling for the region at two times prior to the flare, using
the flux rope insertion method. The models include the non-force-free
effect of magnetic buoyancy in the photosphere. The best-fit NLFFF
models show good fit to observations both in the corona (X-ray and EUV
loops) and chromosphere (H-alpha filament). We find that the horizontal
fields in the photosphere are relatively insensitive to the present of
flux ropes in the corona. The axial flux of the flux rope in the NLFFF
model on May 17 is twice that on May 16, and the model on May 17 is only
marginally stable. We also find that the quasi-circular flare ribbons
are associated with the separatrix between open and closed fields. This
observation and NLFFF modeling suggest that this flare may be triggered
by the reconnection at the null point on the separatrix surface.

---------------------------------------------------------
Title: Stigmatic grazing-incidence x-ray spectrograph for solar
coronal observations
Authors: Kobayashi, Ken; Cirtain, Jonathan; Golub, Leon; Korreck,
Kelly; Cheimets, Peter; Hertz, Edward; Caldwell, David
2010SPIE.7732E..33K Altcode: 2010SPIE.7732E..98K
We present the design for a stigmatic grazing incidence X-ray
spectrograph designed for solar coronal observations. The
spectrograph is composed of a slit, a pair of paraboloid mirrors
and a plano varied-line-space grating. All reflective surfaces of
the spectrograph operate at an angle of incidence of 88 degrees, and
covers a wavelength range of 0.6 to 2.4nm (0.5 to 2.0keV). The design
achieves 1.5pm spectral resolution and 15 μm spatial resolution over
a 2.5mmlong slit. The current spectrograph design is intended for a
sounding rocket experiment, and designed to fit inside a NASA sounding
rocket payload behind a 1.1m focal length Wolter Type-1 telescope. This
combination will have a 2.5arcsec spatial resolution and a 8 arcminute
slit length. We are currently fabricating a laboratory prototype of
the spectrograph to demonstrate the performance and establish the
alignment procedures for a flight model.

---------------------------------------------------------
Title: Coronal Loop Evolution and Inferred Coronal Magnetic Energy
in a Quiet Active Region
Authors: Lee, Jin-Yi; Barnes, G.; Leka, K.; Reeves, K. K.; Korreck,
K. E.; Golub, L.
2010AAS...21640514L Altcode: 2010BAAS...41R.891L
We investigate changes in the properties of the coronal magnetic field
in the context of different emission of coronal loops. Observations by
the Transition Region and Coronal Explorer (TRACE), the Hinode/X-ray
Telescope (XRT), and the SOHO/Michelson Doppler Imager (MDI), the
X-ray and EUV light curves as well as the photospheric magnetic flux
of NOAA active region 10963 are utilized to compare the coronal and
photospheric magnetic fields. A Magnetic Charge Topology (MCT) model
is used to establish potential magnetic field connectivity of the
surface magnetic flux distribution. A Minimum Current Corona (MCC)
model is applied to determine the coronal currents and quantify the
energy build-up. The results of the MCC analysis are compared to the
evolution of the coronal loop brightness, comparing areas of steady
emission, transient emission, and temporal patterns of emission which
imply coronal cooling.

---------------------------------------------------------
Title: Asymmetric Structure of Quiescent Filament Channels Observed
by Hinode/XRT and STEREO/EUVI
Authors: Su, Yingna; van Ballegooijen, A.; Golub, L.
2010AAS...21640513S Altcode: 2010BAAS...41..891S
We present a study on the structure of quiescent filament channels
observed by Hinode/XRT and STEREO/EUVI from December 2006 to February
2009. For 10 channels identified on the solar disk, we find that the
emission on the two sides of the channel is asymmetric in both X-rays
and EUV: one side has curved bright features while the other side
has straight faint features. We interpret the results in terms of a
magnetic flux rope model. The asymmetry in the emission is due to the
variation in axial magnetic flux along the channel, which causes one
polarity to turn into the flux rope, while the field lines from the
other polarity are open or connected to very distant sources. For 70
channels identified by cavities at the limb, the asymmetry cannot be
clearly identified. US members of the XRT team are supported by NASA
contract NNM07AB07C to Smithsonian Astrophysical Observatory.

---------------------------------------------------------
Title: Statistical Study of CMEs with and without Distinct Low
Coronal Signatures
Authors: Ma, Suli; Attrill, G. D. R.; Golub, L.; Lin, J.; Wills-Davey,
M. J.
2010AAS...21640804M Altcode: 2010BAAS...41R.816M
Taking advantage of the two viewpoints of the STEREO spacecraft,
we present a statistical study of CMEs with and without distinct
low coronal signatures from January 1st to August 31st, 2009. During
this period, the line of sight of STEREO A and that of STEREO B are
almost perpendicular and nearly a quarter of the Sun was observed by
both. We identified 35 front-side (as viewed from Earth) CMEs, around
half of which had no distinct low coronal signature (such as dimming,
coronal wave, filament eruption, post-eruptive arcade). Study of the CME
kinematics showed that in the COR2 field of view there is no obvious
difference between CMEs with and without low coronal signatures. The
data from COR1 and EUVI suggest that both kinds of CMEs originate
from below 1.4Rsun. We conclude that the region between
1.1-1.4Rsun is very important for understanding the nascent
development of CMEs. Detailed study indicates that although there may
be no major low coronal signatures for half of the CMEs, there still
exist some subtle changes in the low corona before or during the CME
appearance. Finally, this work acknowledges that automatic space weather
detection systems based on low coronal signatures totally independent of
coronagraph data, may fail to detect a significant proportion of CMEs.

---------------------------------------------------------
Title: Coronal Fine Linear Rays: Are They Fast Streams From Active
Regions?
Authors: Koutchmy, Serge; Lamy, Philippe; Viladrich, Christian;
Filippov, Boris; Nikoghossian, Arthur; Golub, Leon
2010AIPC.1216..339K Altcode:
Eclipse observations of the W-L corona show linear rays above active
regions at times of solar maximum. We show that these linear rays are
also observed in the field-of-view of the C2-LASCO coronagraph, in
perfect correspondence with the eclipse results. A selected prominent
case taken from the 2001 eclipse observation in Angola is analysed
with several different methods, including the use of a synoptic map
constructed using SoHO/LASCO C2 images. A clear signature of time
variations near the eclipse observation is detected, suggesting that
at least some parts of the beam are collimated. These observations
strongly suggest high speed streams that apparently ignore the potential
large scale coronal magnetic field rooted rather low in the corona. A
possible origin is the neutral magnetic points located above the
active region. Several mechanisms exist to explain how the plasma is
accelerated in these regions to large quasi-relativistic velocities,
possibly related to the occurrence of type III radio bursts. We point
out a curious analogy with phenomena occurring inside coronal holes.

---------------------------------------------------------
Title: Is there a flare-like precursor of EUV waves and CMEs ?
Authors: Filippov, Boris; Podladhikova, Olena; Golub, Leon; Koutchmy,
Serge
2010cosp...38.2889F Altcode: 2010cosp.meet.2889F
Filament eruptions with a flux rope are usually considered the cause
of CMEs. It is however not clear why after reaching some critical
height, the filament suddenly erupts and whether or not we always have
a one to one correspondence. Additional factors can be considered,
starting with the ubiquitous chromospheric (in H) and/or coronal
running disturbances or waves seen with EUV and SXR filtergrams
collected by different missions, including the newly operated SWAP
of Proba-2, the GOES 14 SXR patrol instrument and the high resolution
XRT of Hinode. The eruptions seem to be induced by a well focused but
large explosive event originating from an unresolved region presumably
situated rather low in the atmosphere, near the chromosphere-corona
interface. A similar picture can be drawn from a new type of coronal
flare observed with the XRT of Hinode outside of any active region
and without any precursor. Both the quasi-thermal coronal flare and
the large dynamical phenomenon originate or start from a very small
unresolved region. We discuss the difference in mass, momentum and
amount of energy involved for 2 selected events (25 Dec 2006 with
XRT and 5 Feb 2010 with SWAP and other instruments) that are well
documented. We want to examine at what height in the atmosphere these
events are triggered and what is the relevance to the CME phenomenon,
without speculating on the unresolved magnetic field context. The
events were observed at solar activity minimum without any complication
resulting from numerous active regions being present on the disk.

---------------------------------------------------------
Title: Modeling Twisted Coronal Loops: AR 10938
Authors: Golub, L.; Engell, A. J.; van Ballegooijen, A. A.; Korreck,
K. E.; Reeves, K. K.
2009ASPC..415..268G Altcode:
When modeling coronal loops by calculating the potential field
from magnetograms it is often found that field lines highlighted
of the potential field do not match the coronal loops observed in
the data. To rectify this situation, we construct a non-potential
field in which helical “twisted” currents with prescribed radii
are inserted along certain potential field lines. We then relax
the magnetic field to a non-linear force-free field (NLFFF) using
magneto-frictional relaxation. In doing so, we find that we are able
to approach a geometrical match between the field lines and the coronal
loops observed in AR 10938 on January 18, 2007.

---------------------------------------------------------
Title: Jet phenomena above null points of the coronal magnetic field
Authors: Filippov, B.; Koutchmy, S.; Golub, L.
2009Ge&Ae..49.1109F Altcode:
Short-lived plasma jets of various scales, from giant X-ray jets more
than 300 Mm in extent to numerous small jets with sizes typical of
macrospicules, are the phenomena observed in the solar corona in extreme
ultraviolet and X-ray emission. Small jets are particularly prominent
in polar coronal holes. They are close neighbors of tiny bright loops
and coincide in time with their sudden brightening and increase in
size. The geometric shape of the jets and their location suggest
that they arise near singular null points of the coronal magnetic
field. These points appear in coronal holes due to the emergence
of small bipolar or unipolar magnetic structures within large-scale
unipolar cells. Polar jets show a distinct vertical plasma motion in
a coronal hole that introduces significant momentum and mass into the
solar wind flow. Investigating the dynamics of polar jets can elucidate
certain details in the problem of fast solar wind acceleration.

---------------------------------------------------------
Title: EUV Solar Instrument Development at the Marshall Space
Flight Center
Authors: Kobayashi, K.; Cirtain, J. W.; Davis, J. M.; West, E.; Golub,
L.; Korreck, K. E.; Tsuneta, S.; Bando, T.
2009AGUFMSH33B1500K Altcode:
The three sounding rocket instrument programs currently underway at
the NASA Marshall Space Flight Center represent major advances in solar
observations, made possible by improvements in EUV optics and detector
technology. The Solar Ultraviolet Magnetograph Instrument (SUMI) is an
EUV spectropolarimeter designed to measure the Zeeman splitting of two
chromospheric EUV lines, the 280 nm MgII and 155 nm CIV lines. SUMI
directly observes the magnetic field in the low-beta region where
most energetic phenomena are though to originate. In conjunction with
visible-light magnetographs, this observation allows us to track the
evolution of the magnetic field as it evolves from the photosphere to
the upper chromosphere. SUMI incorporates a normal incidence Cassegrain
telescope, a MgF2 double-Wollaston polarizing beam splitter and two TVLS
(toroidal varied line space) gratings, and is capable of observing two
orthogonal polarizations in two wavelength bands simultaneously. SUMI
has been fully assembled and tested, and currently scheduled for
launch in summer of 2010. The High-resolution Coronal Imager is a
normal-incidence EUV imaging telescope designed to achieve 0.2 arcsecond
resolution, with a pixel size of 0.1 arcsecond. This is a factor of
25 improvement in aerial resolution over the Transition Region And
Coronal Explorer (TRACE). Images obtained by TRACE indicate presence of
unresolved structures; higher resolution images will reveal the scale
and topology of structures that make up the corona. The telescope
mirrors are currently being fabricated, and the instrument has been
funded for flight. In addition, a Lyman alpha spectropolarimeter is
under development in collaboration with the National Astronomical
Observatory of Japan. This aims to detect the linear polarization in
the chromosphere caused by the Hanle effect. Horizontal magnetic fields
in the chromosphere are expected to be detectable as polarization near
disk center, and off-limb observations will reveal the magnetic field
structure of filaments and prominences. Laboratory tests of candidate
optical components are currently underway.

---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS) Small Explorer
Authors: de Pontieu, B.; Title, A. M.; Schryver, C. J.; Lemen, J. R.;
Golub, L.; Kankelborg, C. C.; Carlsson, M.
2009AGUFMSH33B1499D Altcode:
The Interface Region Imaging Spectrograph (IRIS) was recently selected
as a small explorer mission by NASA. The primary goal of IRIS is to
understand how the solar atmosphere is energized. The IRIS investigation
combines advanced numerical modeling with a high resolution 20 cm UV
imaging spectrograph that will obtain spectra covering temperatures
from 4,500 to 10 MK in three wavelength ranges (1332-1358 Angstrom,
1390-1406 Angstrom and 2785-2835 Angstrom) and simultaneous images
covering temperatures from 4,500 K to 65,000 K. IRIS will obtain UV
spectra and images with high resolution in space (1/3 arcsec) and time
(1s) focused on the chromosphere and transition region of the Sun, a
complex dynamic interface region between the photosphere and corona. In
this region, all but a few percent of the non-radiative energy leaving
the Sun is converted into heat and radiation. IRIS fills a crucial gap
in our ability to advance Sun-Earth connection studies by tracing the
flow of energy and plasma through this foundation of the corona and
heliosphere. The IRIS investigation is led by PI Alan Title (LMSAL)
with major participation by the Harvard Smithsonian Astrophysical
Observatory, Montana State University, NASA Ames Research Center,
Stanford University and the University of Oslo (Norway). IRIS is
scheduled for launch in late 2012, and will have a nominal two year
mission lifetime.

---------------------------------------------------------
Title: A New View of Coronal Waves from STEREO
Authors: Ma, S.; Wills-Davey, M. J.; Lin, J.; Chen, P. F.; Attrill,
G. D. R.; Chen, H.; Zhao, S.; Li, Q.; Golub, L.
2009ApJ...707..503M Altcode:
On 2007 December 7, there was an eruption from AR 10977, which also
hosted a sigmoid. An EUV Imaging Telescope (EIT) wave associated with
this eruption was observed by EUVI on board the Solar Terrestrial
Relations Observatory (STEREO). Using EUVI images in the 171 Å and the
195 Å passbands from both STEREO A and B, we study the morphology and
kinematics of this EIT wave. In the early stages, images of the EIT wave
from the two STEREO spacecrafts differ markedly. We determine that the
EUV fronts observed at the very beginning of the eruption likely include
some intensity contribution from the associated coronal mass ejection
(CME). Additionally, our velocity measurements suggest that the EIT
wave front may propagate at nearly constant velocity. Both results
offer constraints on current models and understanding of EIT waves.

---------------------------------------------------------
Title: Evolution of Magnetic Properties for Two Active Regions
Observed by Hinode/XRT and TRACE
Authors: Lee, J. -Y.; Leka, K. D.; Barnes, G.; Reeves, K. K.; Korreck,
K. E.; Golub, L.
2009ASPC..415..279L Altcode:
We investigate two active regions observed by the Hinode X-ray Telescope
(XRT) and the Transition Region and Coronal Explorer (TRACE). One active
region shows constant brightness in both XRT and TRACE observations. The
other active region shows a brightening in the TRACE observation
just after a decrease in X-ray brightness indicating the cooling of a
coronal loop. The coronal magnetic topology is derived using a magnetic
charge topology (MCT) model for these two active regions applied to
magnetograms from the Michelson Doppler Imager (MDI) on board the Solar
and Heliospheric Observatory (SOHO). We discuss the results of the MCT
analysis with respect to the light curves for these two active regions.

---------------------------------------------------------
Title: Magnetic energy build-up and coronal brightness evolution
Authors: Lee, J.; Barnes, G.; Leka, K. D.; Reeves, K. K.; Korreck,
K. E.; Golub, L.
2009AGUFMSH41B1664L Altcode:
We have investigated changes in the properties of the coronal magnetic
field in the context of different emission behaviors of coronal
loops. Using observations by the Transition Region and Coronal Explorer
(TRACE), the Hinode/X-ray Telescope (XRT), and the SoHO/Michelson
Doppler Imager (MDI), NOAA active region 10963 has been analyzed
in depth as to how different coronal signatures compare to inferred
coronal energy build-up. A Magnetic Charge Topology (MCT) model was
used to establish potential magnetic field connectivity of the surface
magnetic flux distribution, and a Minimum Current Corona (MCC) model was
applied to quantify the energy build-up along separator field lines. The
results of the MCC analysis are compared to the evolution of the coronal
brightness, comparing areas of steady emission, very transient emission,
and temporal patterns of emission which imply coronal cooling.

---------------------------------------------------------
Title: Coronal Loop Temperatures Obtained with Hinode XRT: A
Toothpaste-Tube Analogy
Authors: Schmelz, J. T.; Saar, S. H.; Weber, M. A.; Deluca, E. E.;
Golub, L.
2009ASPC..415..299S Altcode:
Multi-filter data observed by the Hinode X-Ray Telescope on 10 and
2007 July 13 were used to investigate the thermal properties of
coronal loops. At several positions along the loops, differential
emission measure analysis revealed a strong peak at log T = 6.1 (which
would predict the presence of a TRACE loop) and a much weaker hot
component (which we speculated might be a nanoflare signature). TRACE
observations, however, did not reveal the predicted loop, so we were
forced to re-examine our assumptions. Good differential emission measure
results require high- and low-temperature constraints, but our data sets
did not contain images from the thinnest and thickest filters, which
would be most likely to provide these constraints. Since differential
emission measure programs aim to match observed intensities and get
low values of χ2, they may place emission measure in high-
and low-temperature bins where it does not belong. We draw an analogy to
squeezing the toothpaste tube in the middle. Our analysis was repeated
for a loop observed on 2007 May 13 when the instrument acquired data
in 11 filters and filter combinations, including both the thinnest and
thickest filters. These results show that the loop is multi-thermal,
with significant emission measure in the range 6.0 &lt; log T &lt; 6.5.

---------------------------------------------------------
Title: A Vigorous Explorer Program
Authors: Elvis, Martin; Beasley, Matthew; Brissenden, Roger;
Chakrabarti, Supriya; Cherry, Michael; Devlin, Mark; Edelstein, Jerry;
Eisenhardt, Peter; Feldman, Paul; Ford, Holland; Gehrels, Neil; Golub,
Leon; Marshall, Herman; Martin, Christopher; Mather, John; McCandliss,
Stephan; McConnell, Mark; McDowell, Jonathan; Meier, David; Millan,
Robyn; Mitchell, John; Moos, Warren; Murray, Steven S.; Nousek, John;
Oegerle, William; Ramsey, Brian; Green, James; Grindlay, Jonathan;
Kaaret, Philip; Kaiser, Mary Elizabeth; Kaltenegger, Lisa; Kasper,
Justin; Krolik, Julian; Kruk, Jeffrey W.; Latham, David; MacKenty,
John; Mainzer, Amanda; Ricker, George; Rinehart, Stephen; Romaine,
Suzanne; Scowen, Paul; Silver, Eric; Sonneborn, George; Stern, Daniel;
Swain, Mark; Swank, Jean; Traub, Wesley; Weisskopf, Martin; Werner,
Michael; Wright, Edward
2009arXiv0911.3383E Altcode:
Explorers have made breakthroughs in many fields of astrophysics. The
science from both these missions contributed to three Nobel Prizes -
Giacconi (2002), Mather, and Smoot (2006). Explorers have: marked the
definitive beginning of precision cosmology, discovered that short
gamma-ray bursts are caused by compact star mergers and have measured
metalicity to redshifts z&gt;6. NASA Explorers do cutting-edge science
that cannot be done by facility-class instruments. The Explorer program
provides a rapid response to changing science and technology, to enable
cutting-edge science at moderate cost. Explorers also enable innovation,
and engage &amp; train scientists, managers and engineers, adding human
capital to NASA and the nation. The astrophysics Explorer launch rate
now being achieved is 1 per 3 years, and budget projections are in the
$150M/year range for the next five years. A newly Vigorous Explorer
Program should be created to: 1. Reach the long-stated goal of annual
astrophysics launches; 2. Find additional launch options for Explorers
and actively encourage cost savings in launchers and spacecraft, such
as new commercial vehicles and innovative partnerships. 3. Mitigate
risk via stronger technical development and sub-orbital programs, and
through longer, more thorough, Phase A programs, potentially reducing
the need for a 30% contingency; 4. Strive to protect the funding for
missions that have reached Phase B, to prevent significant launch
slips and cancellations, with a goal of 4 to 5 years from Phase B to
launch; 5. Review the project management procedures and requirements
to seek cost reductions, including the risk management strategy and
the review and reporting process; 6. Review and possibly modify the
cost caps for all Explorer classes to optimize scientific returns per
dollar. [ABRIDGED]

---------------------------------------------------------
Title: Flare Energy Build-up in a Decaying Active Region Near a
Coronal Hole
Authors: Su, Yingna; van Ballegooijen, Adriaan; Schmieder, Brigitte;
Berlicki, Arkadiusz; Guo, Yang; Golub, Leon; Huang, Guangli
2009ApJ...704..341S Altcode:
A B1.7 two-ribbon flare occurred in a highly non-potential decaying
active region near a coronal hole at 10:00 UT on 2008 May 17. This
flare is "large" in the sense that it involves the entire region,
and it is associated with both a filament eruption and a coronal mass
ejection. We present multi-wavelength observations from EUV (TRACE,
STEREO/EUVI), X-rays (Hinode/XRT), and Hα (THEMIS, BBSO) prior to,
during and after the flare. Prior to the flare, the region contained
two filaments. The long J-shaped sheared loops corresponding to the
southern filament were evolved from two short loop systems, which
happened around 22:00 UT after a filament eruption on May 16. Formation
of highly sheared loops in the southeastern part of the region was
observed by STEREO 8 hr before the flare. We also perform nonlinear
force-free field (NLFFF) modeling for the region at two times prior
to the flare, using the flux rope insertion method. The models include
the non-force-free effect of magnetic buoyancy in the photosphere. The
best-fit NLFFF models show good fit to observations both in the corona
(X-ray and EUV loops) and chromosphere (Hα filament). We find that
the horizontal fields in the photosphere are relatively insensitive
to the present of flux ropes in the corona. The axial flux of the
flux rope in the NLFFF model on May 17 is twice that on May 16,
and the model on May 17 is only marginally stable. We also find that
the quasi-circular flare ribbons are associated with the separatrix
between open and closed fields. This observation and NLFFF modeling
suggest that this flare may be triggered by the reconnection at the
null point on the separatrix surface.

---------------------------------------------------------
Title: Some Like It Hot: Coronal Heating Observations from Hinode
X-ray Telescope and RHESSI
Authors: Schmelz, J. T.; Kashyap, V. L.; Saar, S. H.; Dennis, B. R.;
Grigis, P. C.; Lin, L.; De Luca, E. E.; Holman, G. D.; Golub, L.;
Weber, M. A.
2009ApJ...704..863S Altcode:
We have used Hinode X-Ray Telescope observations and RHESSI upper
limits together to characterize the differential emission measure
(DEM) from a quiescent active region. We find a relatively smooth DEM
curve with the expected active region peak at log T = 6.4. We also
find a high-temperature component with significant emission measure
at log T gsim 7. This curve is consistent with previous observations
of quiescent active regions in that it does not produce observable Fe
XIX lines. It is different from that generated with X-Ray Telescope
(XRT) data alone—RHESSI rules out the possibility of a separate
high-temperature component with a peak of approximately log T = 7.4. The
strength and position of the high-temperature peak in this XRT-only
analysis was, however, poorly determined; adding RHESSI flux upper
limits in the 4-13 keV energy range provide a strong high-temperature
constraint which greatly improves the multi-thermal findings. The
results of the present work as well as those from a growing number
of papers on this subject imply that our previous understanding of
the temperature distribution in active regions has been limited. Hot
plasma (log T ≈ 7) appears to be prevalent, although in relatively
small quantities as predicted by nanoflare models. Other models may
need to be adjusted or updated to account for these new results.

---------------------------------------------------------
Title: Fan-Spine Topology Formation Through Two-Step Reconnection
Driven by Twisted Flux Emergence
Authors: Török, T.; Aulanier, G.; Schmieder, B.; Reeves, K. K.;
Golub, L.
2009ApJ...704..485T Altcode: 2009arXiv0909.2235T
We address the formation of three-dimensional nullpoint topologies
in the solar corona by combining Hinode/X-ray Telescope (XRT)
observations of a small dynamic limb event, which occurred beside
a non-erupting prominence cavity, with a three-dimensional (3D)
zero-β magnetohydrodynamics (MHD) simulation. To this end, we model
the boundary-driven "kinematic" emergence of a compact, intense,
and uniformly twisted flux tube into a potential field arcade that
overlies a weakly twisted coronal flux rope. The expansion of the
emerging flux in the corona gives rise to the formation of a nullpoint
at the interface of the emerging and the pre-existing fields. We unveil
a two-step reconnection process at the nullpoint that eventually yields
the formation of a broad 3D fan-spine configuration above the emerging
bipole. The first reconnection involves emerging fields and a set of
large-scale arcade field lines. It results in the launch of a torsional
MHD wave that propagates along the arcades, and in the formation of
a sheared loop system on one side of the emerging flux. The second
reconnection occurs between these newly formed loops and remote arcade
fields, and yields the formation of a second loop system on the opposite
side of the emerging flux. The two loop systems collectively display
an anenome pattern that is located below the fan surface. The flux that
surrounds the inner spine field line of the nullpoint retains a fraction
of the emerged twist, while the remaining twist is evacuated along
the reconnected arcades. The nature and timing of the features which
occur in the simulation do qualititatively reproduce those observed
by XRT in the particular event studied in this paper. Moreover, the
two-step reconnection process suggests a new consistent and generic
model for the formation of anemone regions in the solar corona.

---------------------------------------------------------
Title: The Solar Corona
Authors: Golub, Leon; Pasachoff, Jay M.
2009soco.book.....G Altcode:
1. Introduction; 2. Brief history of coronal studies; 3. The
coronal spectrum; 4. The solar cycle; 5. Ground-based observations;
6. Observations from space: I. The first 4 decades; 7. Activity of
the inner corona; 8. Observations from space: II. Recent missions;
9. The solar wind; 10. Solar flares and coronal mass ejections; Notes;
References; Index.

---------------------------------------------------------
Title: Does a Polar Coronal Hole's Flux Emergence Follow a Hale-Like
Law?
Authors: Savcheva, A.; Cirtain, J. W.; DeLuca, E. E.; Golub, L.
2009ApJ...702L..32S Altcode:
Recent increases in spatial and temporal resolution for solar telescopes
sensitive to EUV and X-ray radiation have revealed the prevalence of
transient jet events in polar coronal holes. Using data collected by the
X-Ray Telescope on Hinode, Savcheva et al. confirmed the observation,
made first by the Soft X-ray Telescope on Yohkoh, that some jets exhibit
a motion transverse to the jet outflow direction. The velocity of this
transverse motion is, on average, 10 km s-1. The direction
of the transverse motion, in combination with the standard reconnection
model for jet production (e.g., Shibata et al.), reflects the magnetic
polarity orientation of the ephemeral active region at the base of
the jet. From this signature, we find that during the present minimum
phase of the solar cycle the jet-base ephemeral active regions in the
polar coronal holes had a preferred east-west direction, and that this
direction reversed during the cycle's progression through minimum. In
late 2006 and early 2007, the preferred direction was that of the active
regions of the coming sunspot cycle (cycle 24), but in late 2008 and
early 2009 the preferred direction has been that of the active regions
of sunspot cycle 25. These findings are consistent with the observations
of Wilson et al. suggesting that each cycle of solar activity begins
at polar latitudes soon after the onset of the previous cycle.

---------------------------------------------------------
Title: Magnetic Nonpotentiality Accumulation Prior to a "Large"
B1.7 Two-Ribbon Flare
Authors: Su, Yingna; van Ballegooijen, A.; Schmieder, B.; Berlicki,
A.; Guo, Y.; Golub, L.
2009SPD....40.2002S Altcode:
A B1.7 two-ribbon flare occurred in a highly non-potential decaying
active region near a coronal hole at 10:00 UT on May 17, 2008. This
flare is "large" in the sense that it involves the entire region, and
it is associated with both a filament eruption and a CME. We present
multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays
(Hinode/XRT), and H-alpha (THEMIS, BBSO) prior to, during and after
the flare. Prior to the flare, the observed coronal loops are mainly
two sets of highly sheared loops surrounding two filaments. The sheared
loops in the southern part of the region appeared in TRACE around 22:00
UT after a filament ejection on May 16. We also performed non-linear
force free field (NLFFF) modeling for the region prior to the flare,
using the flux rope insertion method. The model at 11:42 UT on May 16 is
based on THEMIS (vector) and MDI magnetograms, and the model at 08:03 UT
on May 17 is based only on MDI magnetogram. The best-fit NLFFF models
show good fit to observations both in the corona (X-ray and EUV loops)
and chromosphere (H-alpha filament). In the photosphere, the vectors
in the best-fit NLFFF model are similar to those in the potential
model. However, in the chromosphere, the vectors in the best-fit NLFFF
model present strong non-potentiality, especially at the end of the
inserted flux rope. We also found that the axial flux of the flux rope
in the NLFFF model on May 17 is much higher than that on May 16.

---------------------------------------------------------
Title: The Off-Axis Properties of the Hinode X-Ray Telescope (XRT):
I. Vignetting Effect
Authors: Shin, Junho; Martens, P. C. H.; Golub, L.; Deluca, E. E.
2009SPD....40.1804S Altcode:
The X-Ray Telescope (XRT) aboard Hinode has observed a variety
of coronal structures in the range of 34x34 arc min field-of-view
(FOV) covering the full solar disk. In general, most astronomical
telescopes are designed such that the best-focused image of an object
can be achieved at or close to the on-axis position, and the optical
performance varies systematically across the FOV. The Sun is, however,
a large object whose size is about 30 arc min and coronal structures
are observed not only at the disc center but also near the limb. For
this reason, the optical structure of solar telescopes should be
designed with care for improving the uniformity of the angular
resolution over the full FOV. Since there is no unique solution for
successfully implementing this kind of off-axis variation, the optical
properties of the XRT have been examined using the data from the ground
experiments as well as from in-flight observations for the calibration
of systematic variations in the FOV. The vignetting effect is an
important optical characteristic for describing the performance of
the telescope, which reflects the ability to collect incoming light
at different locations and different photon energies. Especially,
the determination of this vignetting effect is one of the essential
calibration steps that should be performed before the observed images
are used for any scientific purposes. Because a component of the
XRT vignetting effect shows a wavelength dependence, special care
should be taken when, for example, performing temperature analyses
with thin and thick filters of flares occurring near the solar
limb. In this presentation, we introduce the results of analysis of
pre-launch calibration data obtained from MSFC/XRCF experiments. The
two-dimensional off-axis variation of the XRT point spread function
(PSF) and its energy dependence will be discussed in detail.

---------------------------------------------------------
Title: Observations Of Filament Channels By Hinode/XRT And STEREO/EUVI
Authors: Su, Yingna; van Ballegooijen, A.; Golub, L.
2009SPD....40.1013S Altcode:
We will present preliminary results of an investigation on filament
channels observed by Hinode/XRT and STEREO/EUVI. We selected 8 filament
channels that are located in active region remnants. Filament channels
1, 2 and 3 appear to be the same channel observed at different solar
rotations, and channels 5, 6, 7 and 8 are also the same channel at
different solar rotations. We study the X-ray and EUV structures as
well as the evolution of these channels observed by Hinode/XRT and
STEREO/EUV. The corresponding H-alpha filament information is provided
by KSO and MLSO. In order to understand the magnetic configuration of
filament channels, we will also explore non-linear force-free field
modeling of two selected filament channels. The modeling is based
on flux rope insertion method, and the magnetic field information is
provided by SOLIS.

---------------------------------------------------------
Title: Magnetic Topology and Coronal Brightness Evolution: A Case
Study
Authors: Lee, Jin-Yi; Barnes, G.; Leka, K.; Reeves, K. K.; Korreck,
K. E.; Golub, L.
2009SPD....40.1209L Altcode:
We have applied a Magnetic Charge Topology model to investigate
what changes in the properties of the magnetic field are responsible
for different coronal emission behavior of the coronal loops in two
different active regions. Observations from the X-ray Telescope (XRT)
on board Hinode and the Transition Region and Coronal Expolorer (TRACE)
were used, along with time-series of magnetograms for 24 hours from
the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric
Observatory (SOHO). The magnetic connectivity and separator field
lines were established by potential field extrapolation of the observed
surface magnetic flux distribution. We present the evolution for the
two active regions in terms of the changes in both the connections and
in the separator flux, the latter indicative of locations of possible
energy deposit or release.

---------------------------------------------------------
Title: Hinode X-Ray Telescope Detection of Hot Emission from Quiescent
Active Regions: A Nanoflare Signature?
Authors: Schmelz, J. T.; Saar, S. H.; DeLuca, E. E.; Golub, L.;
Kashyap, V. L.; Weber, M. A.; Klimchuk, J. A.
2009ApJ...693L.131S Altcode: 2009arXiv0901.3122S
The X-Ray Telescope (XRT) on the Japanese/USA/UK Hinode (Solar-B)
spacecraft has detected emission from a quiescent active region
core that is consistent with nanoflare heating. The fluxes from 10
broadband X-ray filters and filter combinations were used to construct
differential emission measure (DEM) curves. In addition to the expected
active region peak at log T = 6.3-6.5, we find a high-temperature
component with significant emission measure at log T &gt; 7.0. This
emission measure is weak compared to the main peak—the DEM is down
by almost three orders of magnitude—which accounts of the fact
that it has not been observed with earlier instruments. It is also
consistent with spectra of quiescent active regions: no Fe XIX lines
are observed in a CHIANTI synthetic spectrum generated using the XRT
DEM distribution. The DEM result is successfully reproduced with a
simple two-component nanoflare model.

---------------------------------------------------------
Title: X-Ray Jet Dynamics in a Polar Coronal Hole Region
Authors: Filippov, Boris; Golub, Leon; Koutchmy, Serge
2009SoPh..254..259F Altcode: 2007arXiv0711.4320F
New X-ray observations of the north polar region taken from the X-ray
Telescope (XRT) of the Hinode spacecraft are used to analyze several
time sequences showing small loop brightenings with a long ray above. We
focus on the formation of the jet and discuss scenarios to explain
the main features of the events: the relationship with the expected
surface magnetism, the rapid and sudden radial motion, and possibly the
heating, based on the assumption that the jet occurs above a null point
of the coronal magnetic field. We conclude that 2-D reconnection models
should be complemented in order to explain the observational details
of these events and suggest that alternative scenarios may exist.

---------------------------------------------------------
Title: On the Structure and Evolution of Complexity in Sigmoids:
A Flux Emergence Model
Authors: Archontis, V.; Hood, A. W.; Savcheva, A.; Golub, L.;
Deluca, E.
2009ApJ...691.1276A Altcode:
Sigmoids are structures with a forward or inverse S-shape, generally
observed in the solar corona in soft X-ray emission. It is believed that
the appearance of a sigmoid in an active region is an important factor
in eruptive activity. The association of sigmoids with dynamic phenomena
such as flares and coronal mass ejections (CMEs) make the study of
sigmoids important. Recent observations of a coronal sigmoid, obtained
with the X-Ray Telescope (XRT) on board Hinode, showed the formation
and eruption phase with high spatial resolution. These observations
revealed that the topological structure of the sigmoid is complex:
it consists of many differently oriented loops that all together
form two opposite J-like bundles or an overall S-shaped structure. A
series of theoretical and numerical models have been proposed, over
the past years, to explain the nature of sigmoids but there is no
explanation on how the aforementioned complexity in sigmoids is built
up. In this paper, we present a flux emergence model that leads to the
formation of a sigmoid, whose structure and evolution of complexity
are in good qualitative agreement with the recent observations. For
the initial state of the experiment a twisted flux tube is placed
below the photosphere. A density deficit along the axis of the tube
makes the system buoyant in the middle and it adopts an Ω-shape as it
rises toward the outer atmosphere. During the evolution of the system,
expanding field lines that touch the photosphere at bald-patches (BPs)
form two seperatrix surfaces where dissipation is enhanced and current
sheets are formed. Originally, each of the BP seperatrix surfaces
has a J-like shape. Each one of the J's consist of reconnected field
lines with different shapes and different relative orientation. The
further dynamical evolution of the emerging flux tube results in the
occurrence of many sites that resemble rotational discontinuities. Thus,
additional current layers are formed inside the rising magnetized volume
increasing the complexity of the system. The reconnected field lines
along these layers form an overall S-shaped structure. The reconnection
process continues to occur leading to the formation of another current
concentration in the middle of the sigmoid where a flaring episode
occurs. This central brightening is accompanied by the eruption of a
flux rope from the central area of the sigmoid and the appearance of
"post-flare" loops underneath the current structure.

---------------------------------------------------------
Title: Observations and Nonlinear Force-Free Field Modeling of Active
Region 10953
Authors: Su, Yingna; van Ballegooijen, Adriaan; Lites, Bruce W.;
Deluca, Edward E.; Golub, Leon; Grigis, Paolo C.; Huang, Guangli;
Ji, Haisheng
2009ApJ...691..105S Altcode:
We present multiwavelength observations of a simple bipolar active
region (NOAA 10953), which produced several small flares (mostly B class
and one C8.5 class) and filament activations from April 30 to May 3 in
2007. We also explore nonlinear force-free field (NLFFF) modeling of
this region prior to the C8.5 flare on May 2, using magnetograph data
from SOHO/MDI and Hinode/SOT. A series of NLFFF models are constructed
using the flux-rope insertion method. By comparing the modeled field
lines with multiple X-ray loops observed by Hinode/XRT, we find that
the axial flux of the flux rope in the best-fit models is (7± 2)×
1020 Mx, while the poloidal flux has a wider range of
(0.1-10)× 1010 Mx cm-1. The axial flux in the
best-fit model is well below the upper limit (~15× 1020
Mx) for stable force-free configurations, which is consistent with the
fact that no successful full filament eruption occurred in this active
region. From multiwavelength observations of the C8.5 flare, we find
that the X-ray brightenings (in both RHESSI and XRT) appeared about 20
minutes earlier than the EUV brightenings seen in TRACE 171 Å images
and filament activations seen in MLSO Hα images. This is interpreted as
an indication that the X-ray emission may be caused by direct coronal
heating due to reconnection, and the energy transported down to the
chromosphere may be too low to produce EUV brightenings. This flare
started from nearly unsheared flare loop, unlike most two-ribbon flares
that begin with highly sheared footpoint brightenings. By comparing
with our NLFFF model, we find that the early flare loop is located
above the flux rope that has a sharp boundary. We suggest that this
flare started near the outer edge of the flux rope, not at the inner
side or at the bottom as in the standard two-ribbon flare model.

---------------------------------------------------------
Title: Observations and analysis of the April 9, 2008 CME using
STEREO, Hinode TRACE and SoHO data
Authors: Reeves, K. K.; Patsourakos, S.; Stenborg, G.; Miralles, M.;
Deluca, E.; Forbes, T.; Golub, L.; Kasper, J.; Landi, E.; McKenzie,
D.; Narukage, N.; Raymond, J.; Savage, S.; Su, Y.; van Ballegooijen,
A.; Vourlidas, A.; Webb, D.
2008AGUFMSH12A..04R Altcode:
On April 9, 2008 a CME originating from an active region behind the limb
was well-observed by STEREO, Hinode, TRACE and SoHO. Several interesting
features connected to this eruption were observed. (1) The interaction
of the CME with open field lines from a nearby coronal hole appeared
to cause an abrupt change in the direction of the CME ejecta. (2) The
prominence material was heated, as evidenced by a change from absorption
to emission in the EUV wavelengths. (3) Because the active region was
behind the limb, the X-Ray Telescope on Hinode was able to take long
enough exposure times to observe a faint current- sheet like structure,
and it was able to monitor the dynamics of the plasma surrounding this
structure. This event is also being studied in the context of activity
that occurred during the Whole Heliosphere Interval (WHI).

---------------------------------------------------------
Title: Hinode, TRACE, SOHO, and Ground-based Observations of a
Quiescent Prominence
Authors: Heinzel, P.; Schmieder, B.; Fárník, F.; Schwartz, P.;
Labrosse, N.; Kotrč, P.; Anzer, U.; Molodij, G.; Berlicki, A.;
DeLuca, E. E.; Golub, L.; Watanabe, T.; Berger, T.
2008ApJ...686.1383H Altcode:
A quiescent prominence was observed by several instruments on
2007 April 25. The temporal evolution was recorded in Hα by the
Hinode SOT, in X-rays by the Hinode XRT, and in the 195 Å channel by
TRACE. Moreover, ground-based observatories (GBOs) provided calibrated
Hα intensities. Simultaneous extreme-UV (EUV) data were also taken by
the Hinode EIS and SOHO SUMER and CDS instruments. Here we have selected
the SOT Hα image taken at 13:19 UT, which nicely shows the prominence
fine structure. We compare this image with cotemporaneous ones taken
by the XRT and TRACE and show the intensity variations along several
cuts parallel to the solar limb. EIS spectra were obtained about half
an hour later. Dark prominence structure clearly seen in the TRACE and
EIS 195 Å images is due to the prominence absorption in H I, He I,
and He II resonance continua plus the coronal emissivity blocking due
to the prominence void (cavity). The void clearly visible in the XRT
images is entirely due to X-ray emissivity blocking. We use TRACE, EIS,
and XRT data to estimate the amount of absorption and blocking. The
Hα integrated intensities independently provide us with an estimate of
the Hα opacity, which is related to the opacity of resonance continua
as follows from the non-LTE radiative-transfer modeling. However,
spatial averaging of the Hα and EUV data have quite different natures,
which must be taken into account when evaluating the true opacities. We
demonstrate this important effect here for the first time. Finally,
based on this multiwavelength analysis, we discuss the determination
of the column densities and the ionization degree of hydrogen in
the prominence.

---------------------------------------------------------
Title: Small-scale Coronal Jets
Authors: Koutchmy, S.; Filippov, B.; Golub, L.
2008ESPM...12.2.93K Altcode:
Jet-like events are observed on different scales in the solar corona
in EUV and X-rays. They range from gigantic coronal X-ray jets greater
than 300 Mm in length to small but numerous jetlets. Polar coronal holes
show a significant activity manifested in small loop brightenings and
jetlet formation. Geometrical shape of the jetlets and their position
indicate that they appear near the singular points of the magnetic
field, namely, null points or X-points. These nulls arise due to the
interaction between new emerging small dipoles and large-scale magnetic
field of the coronal hole. The jetlets reveal some real observable
vertical mass motion inside the coronal hole. It is difficult to measure
the radial velocity of plasma within the jetlets but it seems large
enough to significantly contribute as a large momentum into the solar
wind. Finally jetlets could serve as injectors to the process of the
solar fast wind acceleration. We believe that similar but even smaller
processes could very often happen at smaller scale in the chromosphere
near emerging magnetic ephemeral regions forming numerous jetlets of
the upper chromosphere. They form the upper chromosphere and follow
the direction of the surrounding magnetic field. At the epoch of low
activity, the difference in the large-scale structure of the polar
magnetic field and that of the low latitude quiet region magnetic
field results in a prolateness of the chromosphere.

---------------------------------------------------------
Title: Hinode/XRT Diagnostics of Loop Thermal Structure
Authors: Reale, F.; Parenti, S.; Reeves, K. K.; Weber, M.; Bobra,
M. G.; Barbera, M.; Kano, R.; Narukage, N.; Shimojo, M.; Sakao, T.;
Peres, G.; Golub, L.
2008ASPC..397...50R Altcode:
We investigate possible diagnostics of the thermal structure of coronal
loops from Hinode/XRT observations made with several filters. We
consider the observation of an active region with five filters. We
study various possible combinations of filter data to optimize for
sensitivity to thermal structure and for signal enhancement.

---------------------------------------------------------
Title: Vertical Temperature Structures of the Solar Corona Derived
with the Hinode X-Ray Telescope
Authors: Kano, Ryouhei; Sakao, Taro; Narukage, Noriyuki; Tsuneta,
Saku; Kotoku, Jun'ichi; Bando, Takamasa; Deluca, Edward; Lundquist,
Loraine; Golub, Leon; Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo,
Masumi; Shibasaki, Kiyoto; Shimizu, Toshifumi; Nakatani, Ichiro
2008PASJ...60..827K Altcode:
We obtained temperature structures in faint coronal features
above and near the solar limb with the X-Ray Telescope aboard the
Hinode satellite by accurately correcting the scattered X-rays
from surrounding bright regions with occulted images during
the solar eclipses. Our analysis yields a polar coronal hole
temperature of about 1.0MK and an emission measure in the range of
1025.5-1026.0cm-5. In addition,
our methods allow us to measure the temperature and emission
measure of two distinct quiet-Sun structures: radial (plume-like)
structures near the boundary of the coronal-hole and diffuse quiet
Sun regions at mid-latitudes. The radial structures appear to have
increasing temperature with height during the first 100Mm, and
constant temperatures above 100Mm. For the diffuse quiet-Sun region
the temperatures are the highest just above the limb, and appear
to decrease with height. These differences may be due to different
magnetic configurations.

---------------------------------------------------------
Title: The Hinode X-Ray Telescope (XRT): Camera Design, Performance
and Operations
Authors: Kano, R.; Sakao, T.; Hara, H.; Tsuneta, S.; Matsuzaki, K.;
Kumagai, K.; Shimojo, M.; Minesugi, K.; Shibasaki, K.; DeLuca, E. E.;
Golub, L.; Bookbinder, J.; Caldwell, D.; Cheimets, P.; Cirtain, J.;
Dennis, E.; Kent, T.; Weber, M.
2008SoPh..249..263K Altcode:
The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing
incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has
1 arcsec pixels with a wide field of view of 34×34 arcmin. It is
sensitive to plasmas with a wide temperature range from &lt; 1 to 30
MK, allowing us to obtain TRACE-like low-temperature images as well as
Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data
Processor (MDP) controls the XRT through sequence tables with versatile
autonomous functions such as exposure control, region-of-interest
tracking, flare detection, and flare location identification. Data are
compressed either with DPCM or JPEG, depending on the purpose. This
results in higher cadence and/or wider field of view for a given
telemetry bandwidth. With a focus adjust mechanism, a higher resolution
of Gaussian focus may be available on-axis. This paper follows the
first instrument paper for the XRT (Golub et al., Solar Phys.243, 63,
2007) and discusses the design and measured performance of the X-ray
CCD camera for the XRT and its control system with the MDP.

---------------------------------------------------------
Title: Analysis and interpretation of a fast limb CME with eruptive
prominence, C-flare, and EUV dimming
Authors: Koutchmy, S.; Slemzin, V.; Filippov, B.; Noens, J. -C.;
Romeuf, D.; Golub, L.
2008A&A...483..599K Altcode: 2008arXiv0801.2746K
Aims: Coronal mass ejections or CMEs are large dynamical solar-corona
events. The mass balance and kinematics of a fast limb CME, including
its prominence progenitor and the associated flare, will be compared
with computed magnetic structures to look for their origin and
effect. Methods: Multi-wavelength ground-based and spaceborne
observations are used to study a fast W-limb CME event of December
2, 2003, taking into account both on and off disk observations. Its
erupting prominence is measured at high cadence with the Pic du Midi
full Hα line-flux imaging coronagraph. EUV images from SOHO/EIT and
CORONAS-F/SPIRIT space instruments are processed including difference
imaging. SOHO/LASCO images are used to study the mass excess and
motions. Computed coronal structures from extrapolated surface
magnetic fields are compared to observations. Results: A fast
bright expanding coronal loop is identified in the region recorded
slightly later by GOES as a C7.2 flare, followed by a brightening and
an acceleration phase of the erupting material with both cool and hot
components. The total coronal radiative flux dropped by ~7% in the
19.5 nm channel and by 4% in the 17.5 nm channel, revealing a large
dimming effect at and above the limb over a 2 h interval. The typical
3-part structure observed 1 h later by the Lasco C2 and C3 coronagraphs
shows a core shaped similarly to the eruptive filament/prominence. The
total measured mass of the escaping CME (~1.5×1016 g from
C2 LASCO observations) definitely exceeds the estimated mass of the
escaping cool prominence material although assumptions made to analyze
the Hα erupting prominence, as well as the corresponding EUV darkening
of the filament observed several days before, made this evaluation
uncertain by a factor of 2. This mass budget suggests that the event
is not confined to the eruption region alone. From the current free
extrapolation we discuss the shape of the magnetic neutral surface
and a possible scenario leading to an instability, including the small
scale dynamics inside and around the filament.

---------------------------------------------------------
Title: Observations and NLFFF Modeling of Active Region 10953
Authors: Su, Y.; van Ballegooijen, A.; Golub, L.; Deluca, E.
2008AGUSMSP43C..07S Altcode:
We explored the non-linear force free field (NLFFF) modeling of a
simple bipolar active region (NOAA 10953), which produced several small
flares (mostly B class and one C8.5 class) and filament activations
from April 30 to May 3 in 2007. These events appear to be associated
with the frequent flux cancellations (SOHO/MDI) that occurred in the
region close to the polarity inversion line. Some preliminary results
of multi-wavelength observations of a C8.5 flare that occurred on May
2 will be presented. We constructed a series of NLFFF models for this
active region at three times, using the flux-rope insertion method. The
models are constructed based on MDI magnetograms, and constrained by
Hα filaments and highly sheared loops observed by XRT aboard Hinode. We
find good NLFFF models that fit the observations before the C8.5 flare,
but not for the case after the flare. The flux rope contains highly
sheared but weakly twisted magnetic fields. Before the C8.5 flare,
this active region is close to an eruptiveon state: the axial flux in
the flux rope is close to the upper limit for instability.

---------------------------------------------------------
Title: Magnetic Causes of the Eruption of a Quiescent Filament
Authors: Schmieder, B.; Bommier, V.; Kitai, R.; Matsumoto, T.; Ishii,
T. T.; Hagino, M.; Li, H.; Golub, L.
2008SoPh..247..321S Altcode: 2007SoPh..tmp..213S
During the JOP178 campaign in August 2006, we observed the
disappearance of our target, a large quiescent filament located at
S25°, after an observation time of three days (24 August to 26
August). Multi-wavelength instruments were operating: THEMIS/MTR
("MulTi-Raies") vector magnetograph, TRACE ("Transition Region and
Coronal Explorer") at 171 Å and 1600 Å and Hida Domeless Solar
telescope. Counter-streaming flows (+/−10 km s−1) in the
filament were detected more than 24 hours before its eruption. A slow
rise of the global structure started during this time period with a
velocity estimated to be of the order of 1 km s−1. During
the hour before the eruption (26 August around 09:00 UT) the velocity
reached 5 km s−1. The filament eruption is suspected to
be responsible for a slow CME observed by LASCO around 21:00 UT on 26
August. No brightening in Hα or in coronal lines, no new emerging
polarities in the filament channel, even with the high polarimetry
sensitivity of THEMIS, were detected. We measured a relatively large
decrease of the photospheric magnetic field strength of the network
(from 400 G to 100 G), whose downward magnetic tension provides
stability to the underlying stressed filament magnetic fields. According
to some MHD models based on turbulent photospheric diffusion, this
gentle decrease of magnetic strength (the tension) could act as the
destabilizing mechanism which first leads to the slow filament rise
and its fast eruption.

---------------------------------------------------------
Title: Coronal soft X-ray activity in the quiet Sun
Authors: Grigis, Paolo; Golub, Leon; Deluca, Edward
2008cosp...37.1077G Altcode: 2008cosp.meet.1077G
Small scale coronal activity in the quiet Sun is continuous, ubiquitous
and driven by magnetic fields. Typical manifestations of this activity
are seen in the form of brightenings in X-ray bright points, network
flares, nanoflares. We present high-cadence Hinode/XRT soft X-ray
observations of the quiet Sun corona and a statistical analysis of
its variability on short timescales (minutes to hours). We explore
the connection between this coronal activity (as mapped from the soft
X-ray image sequences) and the underlying magnetic field structures.

---------------------------------------------------------
Title: Observations and NLFFF modeling of active region 10953
Authors: Su, Yingna; van Ballegooijen, Adriaan; Golub, Leon; Deluca,
Edward
2008cosp...37.3075S Altcode: 2008cosp.meet.3075S
We explore the non-linear force free field (NLFFF) modeling of a simple
bipolar active region (NOAA 10953), which produced several small
flares (mostly B class and one C8.5 class) and filament activations
from April 30 to May 3 in 2007. These events appear to be associated
with the frequent flux cancellations (SOHO/MDI) that occurred in the
region close to the polarity inversion line. Some preliminary results
of multi-wavelength observations of a C8.5 flare that occurred on May
2 will be presented. We constructed a series of NLFFF models for this
active region at three times, using the flux-rope insertion method. The
models are constructed based on MDI magnetograms, and constrained by
Hα filaments and highly sheared loops observed by XRT aboard Hinode. We
find good NLFFF models that fit the observations before the C8.5 flare,
but not for the case after the flare. The flux rope contains highly
sheared but weakly twisted magnetic fields. Before the C8.5 flare,
this active region is close to an eruptive state: the axial flux in
the flux rope is close to the upper limit for instability.

---------------------------------------------------------
Title: The Differential Emission Measure and Analysis of X-Ray Bright
Points using Hinode's X-Ray Telescope (XRT)
Authors: Farid, S. I.; Saar, S.; Deluca, E.; Golub, L.; Weber, M.
2007AGUFMSH22A0841F Altcode:
The X-Ray telescope aboard Hinode utilizes up to thirteen filter
combinations with one arc second resolution to provide unprecedented
temperature coverage. In this study, we have used eleven X-Ray filters
to examine the statistical properties of X-ray bright points including
temperature, emission, and size distributions. We have analyzed what
appears to be a population of XRBs that are hotter than the main group
in order to identify any distinguishing properties.We discuss the
results of our analysis and their implications on XBP classification.

---------------------------------------------------------
Title: Slipping Magnetic Reconnection in Coronal Loops
Authors: Aulanier, Guillaume; Golub, Leon; DeLuca, Edward E.; Cirtain,
Jonathan W.; Kano, Ryouhei; Lundquist, Loraine L.; Narukage, Noriyuki;
Sakao, Taro; Weber, Mark A.
2007Sci...318.1588A Altcode:
Magnetic reconnection of solar coronal loops is the main process that
causes solar flares and possibly coronal heating. In the standard
model, magnetic field lines break and reconnect instantaneously at
places where the field mapping is discontinuous. However, another mode
may operate where the magnetic field mapping is continuous but shows
steep gradients: The field lines may slip across each other. Soft
x-ray observations of fast bidirectional motions of coronal loops,
observed by the Hinode spacecraft, support the existence of this
slipping magnetic reconnection regime in the Sun’s corona. This
basic process should be considered when interpreting reconnection,
both on the Sun and in laboratory-based plasma experiments.

---------------------------------------------------------
Title: Evidence for Alfvén Waves in Solar X-ray Jets
Authors: Cirtain, J. W.; Golub, L.; Lundquist, L.; van Ballegooijen,
A.; Savcheva, A.; Shimojo, M.; DeLuca, E.; Tsuneta, S.; Sakao, T.;
Reeves, K.; Weber, M.; Kano, R.; Narukage, N.; Shibasaki, K.
2007Sci...318.1580C Altcode:
Coronal magnetic fields are dynamic, and field lines may misalign,
reassemble, and release energy by means of magnetic reconnection. Giant
releases may generate solar flares and coronal mass ejections and,
on a smaller scale, produce x-ray jets. Hinode observations of polar
coronal holes reveal that x-ray jets have two distinct velocities:
one near the Alfvén speed (~800 kilometers per second) and another
near the sound speed (200 kilometers per second). Many more jets were
seen than have been reported previously; we detected an average of
10 events per hour up to these speeds, whereas previous observations
documented only a handful per day with lower average speeds of 200
kilometers per second. The x-ray jets are about 2 × 103 to
2 × 104 kilometers wide and 1 × 105 kilometers
long and last from 100 to 2500 seconds. The large number of events,
coupled with the high velocities of the apparent outflows, indicates
that the jets may contribute to the high-speed solar wind.

---------------------------------------------------------
Title: Continuous Plasma Outflows from the Edge of a Solar Active
Region as a Possible Source of Solar Wind
Authors: Sakao, Taro; Kano, Ryouhei; Narukage, Noriyuki; Kotoku,
Jun'ichi; Bando, Takamasa; DeLuca, Edward E.; Lundquist, Loraine L.;
Tsuneta, Saku; Harra, Louise K.; Katsukawa, Yukio; Kubo, Masahito;
Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo, Masumi; Bookbinder, Jay
A.; Golub, Leon; Korreck, Kelly E.; Su, Yingna; Shibasaki, Kiyoto;
Shimizu, Toshifumi; Nakatani, Ichiro
2007Sci...318.1585S Altcode:
The Sun continuously expels a huge amount of ionized material into
interplanetary space as the solar wind. Despite its influence on the
heliospheric environment, the origin of the solar wind has yet to
be well identified. In this paper, we report Hinode X-ray Telescope
observations of a solar active region. At the edge of the active region,
located adjacent to a coronal hole, a pattern of continuous outflow of
soft-x-ray emitting plasmas was identified emanating along apparently
open magnetic field lines and into the upper corona. Estimates of
temperature and density for the outflowing plasmas suggest a mass
loss rate that amounts to ~1/4 of the total mass loss rate of the
solar wind. These outflows may be indicative of one of the solar wind
sources at the Sun.

---------------------------------------------------------
Title: Fine Thermal Structure of a Coronal Active Region
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryouhei; Narukage,
Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
2007Sci...318.1582R Altcode:
The determination of the fine thermal structure of the solar corona is
fundamental to constraining the coronal heating mechanisms. The Hinode
X-ray Telescope collected images of the solar corona in different
passbands, thus providing temperature diagnostics through energy
ratios. By combining different filters to optimize the signal-to-noise
ratio, we observed a coronal active region in five filters, revealing
a highly thermally structured corona: very fine structures in the
core of the region and on a larger scale further away. We observed
continuous thermal distribution along the coronal loops, as well as
entangled structures, and variations of thermal structuring along the
line of sight.

---------------------------------------------------------
Title: Magnetic Feature and Morphological Study of X-Ray Bright
Points with Hinode
Authors: Kotoku, Jun'ichi; Kano, Ryouhei; Tsuneta, Saku; Katsukawa,
Yukio; Shimizu, Toshifumi; Sakao, Taro; Shibazaki, Kiyoto; Deluca,
Edward E.; Korreck, Kelly E.; Golub, Leon; Bobra, Monica
2007PASJ...59S.735K Altcode:
We observed X-ray bright points (XBPs) in a quiet region of the Sun
with the X-Ray Telescope (XRT) aboard the Hinode satellite on 2006
December 19. XRT's high-resolution X-ray images revealed many XBPs with
complicated structure and evolving dramatically with time. Almost all
of the dynamic eruptions in the quiet region were composed of XBPs,
and they had either loop or multiloop shapes, as is observed in larger
flares. Brightening XBPs had strong magnetic fields with opposite
polarities near their footpoints. While we have found a possible
example of associated magnetic cancellation, other XBPs brighten and
fade without any associated movement of the photospheric magnetic field.

---------------------------------------------------------
Title: A Study of Polar Jet Parameters Based on Hinode XRT
Observations
Authors: Savcheva, Antonia; Cirtain, Jonathan; Deluca, Edward E.;
Lundquist, Loraine L.; Golub, Leon; Weber, Mark; Shimojo, Masumi;
Shibasaki, Kiyoto; Sakao, Taro; Narukage, Noriyuki; Tsuneta, Saku;
Kano, Ryouhei
2007PASJ...59S.771S Altcode:
Hinode/SOHO campaign 7197 is the most extensive study of polar jet
formation and evolution from within both the north and south polar
coronal holes so far. For the first time, this study showed that the
appearance of X-ray jets in the solar coronal holes occurs at very high
frequency - about 60 jets d-1 on average. Using observations
collected by the X-Ray Telescope on Hinode, a number of physical
parameters from a large sample of jets were statistically studied. We
measured the apparent outward velocity, the height, the width and
the lifetime of the jets. In our sample, all of these parameters show
peaked distributions with maxima at 160kms-1 for the outward
velocity, 5 × 104 km for the height, 8 × 103
km for the width, and about 10min for the lifetime of the jets. We
also present the first statistical study of jet transverse motions,
which obtained transverse velocities of 0-35kms-1. These
values were obtained on the basis of a larger (in terms of frequency)
and better sampled set of events than what was previously statistically
studied (Shimojo et al. 1996, PASJ, 48, 123). The results were made
possible by the unique characteristics of XRT. We describe the methods
used to determine the characteristics and set some future goals. We
also show that despite some possible selection effects, jets preferably
occur inside the polar coronal holes.

---------------------------------------------------------
Title: Evolution of the Sheared Magnetic Fields of Two X-Class Flares
Observed by Hinode/XRT
Authors: Su, Yingna; Golub, Leon; van Ballegooijen, Adriaan; Deluca,
Edward E.; Reeves, Kathy K.; Sakao, Taro; Kano, Ryouhei; Narukage,
Noriyuki; Shibasaki Kiyoto
2007PASJ...59S.785S Altcode:
We present multi-wavelength observations of the evolution of the sheared
magnetic fields in NOAA Active Region 10930, where two X-class flares
occurred on 2006 December 13 and December 14, respectively. Observations
made with the X-ray Telescope (XRT) and the Solar Optical Telescope
(SOT) aboard Hinode suggest that the gradual formation of the sheared
magnetic fields in this active region is caused by the rotation and
west-to-east motion of an emerging sunspot. In the pre-flare phase
of the two flares, XRT shows several highly sheared X-ray loops in
the core field region, corresponding to a filament seen in the TRACE
EUV observations. XRT observations also show that part of the sheared
core field erupted, and another part of the sheared core field stayed
behind during the flares, which may explain why a large part of the
filament is still seen by TRACE after the flare. About 2-3 hours after
the peak of each flare, the core field becomes visible in XRT again,
and shows a highly sheared inner and less-sheared outer structure. We
also find that the post-flare core field is clearly less sheared than
the pre-flare core field, which is consistent with the idea that the
energy released during the flares is stored in the highly sheared
fields prior to the flare.

---------------------------------------------------------
Title: An On-Orbit Determination of the On-Axis Point Spread Function
of the Hinode X-Ray Telescope
Authors: Weber, Mark; Deluca, Edward E.; Golub, Leon; Cirtain,
Jonathan; Kano, Ryouhei; Sakao, Taro; Shibasaki, Kiyoto; Narukage,
Noriyuki
2007PASJ...59S.853W Altcode:
The Hinode X-ray Telescope provides unprecedented observations of
the solar corona in X-rays, due in part to its fine resolution. The
X-ray point spread function (PSF) was measured before launch at the
NASA X-ray Calibration Facility to have a FWHM of 0.8”. This paper
describes the work to verify the PSF measurements using on-orbit
observations of planetary transits and solar eclipses. Analysis of a
Mercury transit gives a PSF FWHM = 1.0" ± 0.12".

---------------------------------------------------------
Title: What Determines the Intensity of Solar Flare/CME Events?
Authors: Su, Yingna; Van Ballegooijen, Adriaan; McCaughey, James;
Deluca, Edward; Reeves, Katharine K.; Golub, Leon
2007ApJ...665.1448S Altcode:
We present a comprehensive statistical study addressing the question of
what determines the intensity of a solar flare and associated coronal
mass ejection (CME). For a sample of 18 two-ribbon flares associated
with CMEs, we have examined the correlations between the GOES soft X-ray
peak flare flux (PFF), the CME speed (VCME) obtained from
SOHO LASCO observations, and six magnetic parameters of the flaring
active region. These six parameters measured from both TRACE and SOHO
MDI observations are: the average background magnetic field strength
(B), the area of the region where B is counted (S), the magnetic
flux of this region (Φ), the initial shear angle (θ1,
measured at the flare onset), the final shear angle (θ2,
measured at the time when the shear change stops), and the change of
shear angle (θ12=θ1-θ2) of the
footpoints. We have found no correlation between θ1
and the intensity of flare/CME events, while the other five
parameters are either positively or negatively correlated with
both log10(PFF) and VCME. Among these five parameters,
Φ and θ12 show the most significant correlations with
log10(PFF) and VCME. The fact that both log10(PFF) and
VCME are highly correlated with θ12 rather
than with θ1 indicates that the intensity of flare/CME
events may depend on the released magnetic free energy rather than
the total free energy stored prior to the flare. We have also found
that a linear combination of a subset of these six parameters shows
a much better correlation with the intensity of flare/CME events than
each parameter itself, and the combination of log10Φ, θ1,
and θ12 is the top-ranked combination.

---------------------------------------------------------
Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
2007SoPh..243....3K Altcode:
The Hinode satellite (formerly Solar-B) of the Japan Aerospace
Exploration Agency's Institute of Space and Astronautical Science
(ISAS/JAXA) was successfully launched in September 2006. As the
successor to the Yohkoh mission, it aims to understand how magnetic
energy gets transferred from the photosphere to the upper atmosphere
and results in explosive energy releases. Hinode is an observatory
style mission, with all the instruments being designed and built to
work together to address the science aims. There are three instruments
onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
(EIS), and the X-Ray Telescope (XRT). This paper provides an overview
of the mission, detailing the satellite, the scientific payload, and
operations. It will conclude with discussions on how the international
science community can participate in the analysis of the mission data.

---------------------------------------------------------
Title: The X-Ray Telescope (XRT) for the Hinode Mission
Authors: Golub, L.; DeLuca, E.; Austin, G.; Bookbinder, J.; Caldwell,
D.; Cheimets, P.; Cirtain, J.; Cosmo, M.; Reid, P.; Sette, A.; Weber,
M.; Sakao, T.; Kano, R.; Shibasaki, K.; Hara, H.; Tsuneta, S.; Kumagai,
K.; Tamura, T.; Shimojo, M.; McCracken, J.; Carpenter, J.; Haight,
H.; Siler, R.; Wright, E.; Tucker, J.; Rutledge, H.; Barbera, M.;
Peres, G.; Varisco, S.
2007SoPh..243...63G Altcode:
The X-ray Telescope (XRT) of the Hinode mission provides an
unprecedented combination of spatial and temporal resolution in solar
coronal studies. The high sensitivity and broad dynamic range of XRT,
coupled with the spacecraft's onboard memory capacity and the planned
downlink capability will permit a broad range of coronal studies over
an extended period of time, for targets ranging from quiet Sun to
X-flares. This paper discusses in detail the design, calibration, and
measured performance of the XRT instrument up to the focal plane. The
CCD camera and data handling are discussed separately in a companion
paper.

---------------------------------------------------------
Title: Atomic force microscopy characterization of Zerodur mirror
substrates for the extreme ultraviolet telescopes aboard NASA's
Solar Dynamics Observatory
Authors: Soufli, Regina; Baker, Sherry L.; Windt, David L.; Gullikson,
Eric M.; Robinson, Jeff C.; Podgorski, William A.; Golub, Leon
2007ApOpt..46.3156S Altcode:
The high-spatial frequency roughness of a mirror operating at extreme
ultraviolet (EUV) wavelengths is crucial for the reflective performance
and is subject to very stringent specifications. To understand
and predict mirror performance, precision metrology is required for
measuring the surface roughness. Zerodur mirror substrates made by two
different polishing vendors for a suite of EUV telescopes for solar
physics were characterized by atomic force microscopy (AFM). The AFM
measurements revealed features in the topography of each substrate
that are associated with specific polishing techniques. Theoretical
predictions of the mirror performance based on the AFM-measured
high-spatial-frequency roughness are in good agreement with EUV
reflectance measurements of the mirrors after multilayer coating.

---------------------------------------------------------
Title: The Dynamics Of Fine Structures In Solar X-ray Jets
Authors: Shimojo, Masumi; Narukage, N.; Kano, R.; Sakao, T.; Tsuneta,
T.; Cirtain, J. W.; Lundquist, L. L.; Deluca, E. E.; Golub, L.
2007AAS...210.9422S Altcode: 2007BAAS...39Q.221S
The X-ray telescope(XRT) aboard HINODE satellite has the great
spatial/time resolution in X-ray range. And, the observations using
XRT have revealed the fine structures of solar corona. From the
observations, we found the fine thread structures in the X-ray jets
and the structures move dynamically like wave. We also found that some
X-ray jets start just after small loop expansion in the footpoint
brightening. The observation results suggest that the reconnection
process X-ray jets is very similar to that in large flares.

---------------------------------------------------------
Title: Coronal Temperature Diagnostics With Hinode X-ray Telescope
Authors: Narukage, Noriyuki; Sakao, T.; Kano, R.; Shimojo, M.; Tsuneta,
S.; Kosugi, T.; Deluca, E. E.; Golub, L.; Weber, M.; Cirtain, J.;
Japan-US X-Ray Telescope Team
2007AAS...210.6304N Altcode: 2007BAAS...39..172N
An X-ray telescope (XRT) on board HINODE satellite observes the Sun
in X-rays with high special resolution (1arcsec 730km on solar the
disk). This telescope has 9 X-ray filters with different temperature
responses. Using these filters, the XRT can detect the coronal
plasma with a wide temperature range from less than 1MK to more
than 10MK. Moreover, based on observations with more than 2 filters,
we can estimate the coronal temperature. In this paper, we use the
filter ratio method for coronal temperature diagnostics. Using this
method, we can easily estimate the averaged temperature of the coronal
plasma along the line-of-sight. This method has been used frequently
in the past, but the high quality XRT data give us temperature maps
with unprecedented accuracy and resolution. The XRT usually takes
the full Sun images with 2 kinds of filters 4 times a day. Using this
data and filter ratio method, we can obtain full Sun temperature maps
with high special resolution. In our analysis, we can derive reliable
temperatures not only in active regions but also in quiet regions and
coronal holes. This map can be created with the data set of one synoptic
observation. This means that we can obtain 4 maps a day. The result is
a full Sun temperature movie that gives us an unprecedented view of the
time evolution of solar temperature. In this meeting, we will show the
full Sun temperature movie and our coronal temperature analysis results.

---------------------------------------------------------
Title: Slip running reconnection in the Sun's atmosphere observed
by RHESSI, SOHO, TRACE and Hinode
Authors: Schmieder, B.; Aulanier, G.; Démoulin, P.; Pariat, E.;
Golub, L.
2007AGUSMSH22A..01S Altcode:
Solar double ribbon flares are commonly explained by magnetic field
reconnections in the high corona. The bright ribbons, typically
observed in Halpha, in EUV with SoHO, TRACE correspond to the ends
of the reconnected loops. In most studied cases, the reconnection
site is an X-point, where two magnetic separatrices intersect. In
this presentation, we show a generalization of this model to 3D
complex magnetic topologies where there are no null points, but
quasi-separatrices layers instead. In that case, while the ribbons
spread away during reconnection, we show that magnetic field lines
can quickly slip along them. We propose that this new phenomenon
could explain also fast moving HXR footpoints as observed by RHESSI,
and that it may be observed in soft X rays with XRT.

---------------------------------------------------------
Title: Magnetic Shear in Two-ribbon Solar Flares
Authors: Su, Yingna; Golub, L.; Van Ballegooijen, A.; McCaughey, J.;
Deluca, E. E.; Reeves, K.; Gros, M.
2007AAS...210.3702S Altcode: 2007BAAS...39Q.151S
To study shear motion of the footpoints in solar flares, we selected
50 X- and M- class two-ribbon flares observed by TRACE (in 1998-2005)
as our data sample. We found that: 1) 86% (43 out of 50) of these
flares show both strong-to-weak shear change of footpoints and ribbon
separation. Shear motion of footpoints is thus a common feature
in two-ribbon flares; 2) the initial and final shear angles of the
footpoints in this type of flare are mainly in the range from 50° to
80° and 15° to 55°, respectively; 3) in 10 out of the 14 events with
both measured shear angle and corresponding hard X-ray observations,
the cessation of shear change is 0-2 minutes earlier than the end of
the impulsive phase. This may suggest that the change from impulsive to
gradual phase is related to magnetic shear change. We then selected 20
flares with measured shear angles and corresponding CMEs from our data
sample. For these flares, we found that the magnetic flux and change
of shear angle show comparably strong correlations with the peak flare
flux and CME speed, while the intial shear angle does not. This result
indicates that the intensity of flare/CME events may depend mainly on
the released magnetic free energy rather than the total magnetic free
energy stored prior to the eruption. After a successful launch last
September, Hinode (Solar-B) caught two X-class solar flares, which
occurred in AR 10930 on Dec 13 and 14, 2006. Using these new datasets
(Hinode/XRT, Hinode/SOT, TRACE, and SOHO/MDI), we carried out a study of
the evolution of the sheared magnetic fields involved in these flares,
and some preliminary results will also be presented. The TRACE analysis
was supported at Smithsonian Astrophysical Observatory by a contract
from Lockheed Martin.

---------------------------------------------------------
Title: Intercalibration of the X-ray Telescope and the EUV Imaging
Spectrometer on Hinode
Authors: Golub, Leon; Cirtain, J.; DeLuca, E. E.; Hara, H.; Warren,
H.; Weber, M.
2007AAS...210.9418G Altcode: 2007BAAS...39..220G
The X-Ray Telescope and the Extreme-Ultra Violet Imaging Spectrometer
on Hinode are designed to measure the emission of excited ions formed
at temperatures ranging from 104-108 K. The
temperature overlap of these two telescope is from 0.7 to 20 MK, and
an on-orbit calibration of the sensitivity of the two instruments
to solar features will provide a basis for future observational
comparisons. Using calibrated samples of data from each instrument,
and relying to a great extent on the CHIANTI spectral code, we have
derived an estimate of the inter-calibration of the two telescope
for a variety of different solar features and conditions. This is a
major step in enhancing our ability to use the instruments together
for providing quantitative diagnostics of the solar plasma.

---------------------------------------------------------
Title: Continuous Upflow of Plasmas at the Edge of an Active Region
as Revealed by the X-ray Telescope (XRT) aboard Hinode
Authors: Sakao, Taro; Kano, R.; Narukage, N.; Kotoku, J.; Bando, T.;
DeLuca, E. E.; Lundquist, L. L.; Golub, L.; Kubo, M.; Katsukawa, Y.;
Tsuneta, S.; Hara, H.; Matsuzaki, K.; Shimojo, M.; Shibasaki, K.;
Shimizu, T.; Nakatani, I.
2007AAS...210.7205S Altcode: 2007BAAS...39Q.179S
We present X-ray imaging observations with Hinode X-Ray Telescope (XRT)
of an active region NOAA AR 10942 made in the period of 20-22 February
2007. A prominent feature that drew our particular attention is that
there revealed continuous upflow of soft-X-ray-emitting plasmas along
apparently-open field lines towards the outer corona emanating from the
edge of the active region. The field lines are originated from
an ensamble of small spots of following polarity, and are located at
a border between the active region and an adjacent equatorial coronal
hole(s) located to the east. The upflow was observed to be continuous
throughout the three days of observation intervals with projected
velocity of 140 km/s, accompanied with undulating motion of the field
lines. We assert that these upflowing plasmas would be a possible
source of slow solar wind material, which supports a foresighted
notion which grew out of interplanetary scintillation observations
that slow solar wind most likely has its origin in the vicinity of
active regions with large flux expansion (Kojima et al. 1999). A
preliminaty analysis indicates that the temperature of the upflowing
material near the base of the field lines is 1.3 MK with number density
of 2 × 109 /cm3. Assuming that all the material
is to escape to the interplanetary space, this leads to a mass loss
rate of 2 × 1011 g/s which amounts to a good fraction of
the total mass loss rate for solar wind. It is noteworthy that, even
apart from this unique upflow, we see continuous (up)flows of plasmas
anywhere around (surrounding) the active region. Details of the
upflow will be presented and their possible implication to slow solar
wind discussed.

---------------------------------------------------------
Title: On-orbit Measurement Of The Hinode/XRT Point Spread Function
Authors: Weber, Mark A.; Cirtain, J.; Golub, L.; DeLuca, E. E.;
Martens, P.; XRT Team
2007AAS...210.9416W Altcode: 2007BAAS...39..220W
The Hinode X-Ray Telescope provides unprecedented observations of
the solar corona in x-rays, due in part to its fine resolution. The
optical point spread function (PSF) was measured before launch at the
NASA X-Ray Calibration Facility to have a FWHM of 0.92 arc-seconds. In
this poster we describe our work to verify the PSF measurements using
on-orbit data. The US XRT team is supported by a contract from NASA to
SAO. Hinode is an international project supported by JAXA, NASA, PPARC,
and ESA. We are grateful to the Hinode team for all their efforts in
the design, development, and operation of the mission.

---------------------------------------------------------
Title: Temperature Structures Above Coronal Hole and Quiet Sun
Authors: Kano, Ryouhei; Sakao, T.; Narukage, N.; Kotoku, J.; Bando,
T.; DeLuca, E. E.; Lundquist, L.; Golub, L.; Tsuneta, S.; Hara, H.;
Shibasaki, K.; Shimojo, M.
2007AAS...210.9436K Altcode: 2007BAAS...39..223K
The X-ray Telescope (XRT) on board Hinode satelite has the capability
to derive the temperature structure in the solar corona. We present
the hieght dependence of the temperature above the limb. Because X-ray
intensity above the limb is so faint, it is important to estimate the
scattered light from disk corona. The eclipses happened on February 17
and March 19 in 2007 at Hinode orbit. On February 17, we took X-ray
images above the south polar coronal hole, while Moon passed it. On
March 19, we took the data for quiet Sun in the same way. We
can estimated the scattered light from the eclipse data, and derived
the scatter-free X-ray images above the solar limb. In this meeting,
we will present the temperatures above coronal hole and quiet Sun,
based on the eclipse data.

---------------------------------------------------------
Title: A Statistical Study of Shear Motion of the Footpoints in
Two-Ribbon Flares
Authors: Su, Yingna; Golub, Leon; Van Ballegooijen, Adriaan A.
2007ApJ...655..606S Altcode:
We present a statistical investigation of shear motion of the
ultraviolet (UV) or extreme-ultraviolet (EUV) footpoints in two-ribbon
flares, using the high spatial resolution data obtained in 1998-2005
by TRACE. To do this study, we have selected 50 well-observed X and
M class two-ribbon flares as our sample. All 50 of these flares are
classified into three types based on the motions of the footpoints
with respect to the magnetic field (SOHO MDI). The relation between our
classification scheme and the traditional classification scheme (i.e.,
“ejective” and “confined” flares) is discussed. We have found that
86% (43 out of 50) of these flares show both strong-to-weak shear
change of footpoints and ribbon separation (type I flares), and 14%
of the flares show no measurable shear change of conjugate footpoints,
including two flares with very small ribbon separation (type II flares)
and five flares having no ribbon separation at all through the entire
flare process (type III flares). Shear motion of footpoints is thus a
common feature in two-ribbon flares. A detailed analysis of the type
I flares shows (1) for a subset of 20 flares, the initial and final
shear angles of the footpoints are mainly in the range 50°-80° and
15°-55°, respectively; and (2) in 10 of the 14 flares having both
measured shear angle and corresponding hard X-ray observations, the
cessation of shear change is 0-2 minutes earlier than the end of the
impulsive phase, which may suggest that the change from impulsive to
gradual phase is related to magnetic shear change.

---------------------------------------------------------
Title: Magnetic activity and the solar corona: first results from
the Hinode satellite .
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryohei; Narukage,
Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
2007MmSAI..78..591R Altcode:
The structure, dynamics and evolution of the solar corona are governed
by the magnetic field. In spite of significant progresses in our insight
of the physics of the solar corona, several problems are still under
debate, e.g. the role of impulsive events and waves in coronal heating,
and the origin of eruptions, flares and CMEs. The Hinode mission has
started on 22 september 2006 and aims at giving new answers to these
questions. The satellite contains three main instruments, two high
resolution telescopes, one in the optical and one in the X-ray band,
and an EUV imaging spectrometer. On the Italian side, INAF/Osservatorio
Astronomico di Palermo has contributed with the ground-calibration
of the filters of the X-ray telescope. We present some preliminary
mission results, with particular attention to the X-ray telescope data.

---------------------------------------------------------
Title: Coronal Dynamics and the AIA on SDO
Authors: Golub, L.
2007sdeh.book...23G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: First Results From The Solar-B Mission, Part I
Authors: Golub, L.; International Members, S.
2006AGUFMSH23A0337G Altcode:
The Solar-B Observatory is a highly capable satellite equipped with
three advanced solar telescopes. Its solar optical telescope (SOT) has
an unprecedented 0.2 arcsec resolution for observation of the solar
atmosphere from space in multiple optical passbands. It will also,
for the first time, measure the vector magnetic fields from space. The
X-ray telescope (XRT) has broad temperature coverage and a spatial
a resolution three times as high as Yohkoh. The image cadence will
be significantly higher than Yohkoh's and a flare buffer will provide
exceptional capability for observing rapid changes at flare onset. The
EUV imaging spectrometer (EIS) has sensitivity ten times as high as the
ESA SOHO instrument and covers a broad range of transition region and
coronal temperatures. Flexible operating modes permit slit, slot and
raster options in a selectable number of spectral lines. Both XRT and
EIS have 2 arcsec spatial resolution (1 arcsec pixels). Solar-B is the
follow-up mission to the very successful Japan/UK/US Yohkoh mission. We
present a status report from the initial operation of the observatory,
showing some of the first observations obtained. Following a short
commissioning phase, science planning and regular operations are due to
begin January 2007. All mission data will be open and freely available
to researchers shortly after receipt at the DARTS data archive hosted
in Japan.

---------------------------------------------------------
Title: Analysis of Magnetic Shear in An X17 Solar Flare on October
28, 2003
Authors: Su, Y. N.; Golub, L.; Van Ballegooijen, A. A.; Gros, M.
2006SoPh..236..325S Altcode:
An X17 class (GOES soft X-ray) two-ribbon solar flare on October 28,
2003 is analyzed in order to determine the relationship between the
timing of the impulsive phase of the flare and the magnetic shear change
in the flaring region. EUV observations made by the Transition Region
and Coronal Explorer (TRACE) show a clear decrease in the shear of
the flare footpoints during the flare. The shear change stopped in the
middle of the impulsive phase. The observations are interpreted in terms
of the splitting of the sheared envelope field of the greatly sheared
core rope during the early phase of the flare. We have also investigated
the temporal correlation between the EUV emission from the brightenings
observed by TRACE and the hard X-ray (HXR) emission (E &gt; 150 keV)
observed by the anticoincidence system (ACS) of the spectrometer SPI
on board the ESA INTEGRAL satellite. The correlation between these
two emissions is very good, and the HXR sources (RHESSI) late in the
flare are located within the two EUV ribbons. These observations are
favorable to the explanation that the EUV brightenings mainly result
from direct bombardment of the atmosphere by the energetic particles
accelerated at the reconnection site, as does the HXR emission. However,
if there is a high temperature (T &gt; 20 MK) HXR source close to the
loop top, a contribution of thermal conduction to the EUV brightenings
cannot be ruled out.

---------------------------------------------------------
Title: The Atmospheric Imaging Assembly (AIA) for the Solar Dynamics
Observatory
Authors: Smith, Peter L.; Golub, L.; Bookbinder, J. A.; Reid, P. B.;
Deluca, E. E.; Cheimets, P. N.; Podgorski, W. A.; Title, A. M.; Lemen,
J. R.; Boerner, P. F.; SAO, Science, and LMSAL Engineering Teams
2006SPD....37.0119S Altcode: 2006BAAS...38Q.218S
The Atmospheric Imaging Assembly (AIA) is being developed for the
Solar Dynamics Observatory (SDO), which is designed to study the
Sun as part of NASA's Living With a Star program. AIA comprises
four normal-incidence telescopes with multilayer-coated optics;
entrance-aperture and focal-plane filters limit the bandpasses. Solar
radiation from the upper solar atmosphere at six wavelengths
corresponding to temperatures between 6.3×105 and
1.5×107 K [Fe IX (171 Å) Fe XII, XXIV (193 Å) Fe XIV
(211 Å) Fe XVI (335 Å) Fe XVIII (94 Å) and Fe XX, XXIII (131 Å)]
will be recorded with high spatial resolution (0.6 arcsec pixels). Other
channels enable observations of the chromosphere (He II 304 Å C IV
1550 Å) and the photosphere. Each telescope contains a 4096 x 4096
CCD camera system and has a 41 arcmin field of view. AIA will return 8
full-solar-disk images every 10 s. The 5-year SDO mission is scheduled
to launch in late 2008. The imaging performance of the telescopes,
which are being provided by the Smithsonian Astrophysical Observatory,
and performance of the multilayer coatings, which are responsible for
the large effective area of AIA, will be discussed in the context of
AIA science goals.

---------------------------------------------------------
Title: The Hi-C Sounding Rocket Experiment
Authors: Golub, Leon; Cirtain, J.; DeLuca, E.; Nystrom, G.; Kankelborg,
C.; Klumpar, D.; Longcope, D.; Martens, P.
2006SPD....37.0605G Altcode: 2006BAAS...38R.226G
The High-resolution Coronal Imager, Hi-C, is a pathfinder
mission designed to place significant new limits on theories of
coronal heating and dynamics by measuring the structures at size
scales relevant to reconnection physics. The Hi-C instrument uses
normal-incidence EUV multilayer technology, as developed in the
NIXT and TRACE programs. A dual-channel long focal-length telescope
and large format back-illuminated CCD camera provide spectroscopic
imaging of the corona at 0.1 arcsec resolution.The main objective of
the Hi-C investigation is to determine the geometric configuration and
topology of the structures making up the inner corona. The secondary
objective is to examine the dynamics of those structures, within the
constraints of the 300-seconds of observing time available from a
sounding rocket. The mission is designed to study the mechanisms for
growth, diffusion and reconnection of magnetic fields, and to help
understand the coupling of small-scale dynamic and eruptive processes
to large-scale dynamics.Hi-C will benefit from a unique coordinated
observation opportunity with investigations such as AIA on SDO, XRT on
Solar-B, and STEREO. Hi-C will address basic plasma physics science
goals of the SSSC by observing the small-scale processes that are
ubiquitous in hot magnetized coronal plasma. The scientific objectives
of Hi-C are central to the SSSC goal of understanding the Sun's activity
and its effects on the terrestrial environment, by providing unique
and unprecedented views of the dynamic activity in the solar atmosphere.

---------------------------------------------------------
Title: Magnetic Shear Change in Solar Flares
Authors: Su, Yingna; Golub, L.; Van Ballegooijen, A.
2006SPD....37.0827S Altcode: 2006BAAS...38..235S; 2006SPD....37.0827Y
It is well known that during a two-ribbon flare the two footpoint
ribbons, residing in opposite magnetic polarities, expand outward and
away from each other. However, the shear motion of the footpoints
along the direction parallel to the magnetic inversion line has
only been examined by several authors in some individual two-ribbon
flares. This motion, also described as shear change of the footpoints,
is interpreted by a magnetic field model with a highly sheared inner and
less sheared outer magnetic field configuration during the pre-flare
phase, and the cessation of the shear change during the impulsive
phase is interpreted as a splitting of the envelope of the highly
sheared core field. We have made a statistical investigation of the
EUV footpoint shear motion along the direction parallel to the magnetic
inversion line in two-ribbon flares, using the high spatial resolution
data obtained in 1998-2005 by Transition Region and Coronal Explorer
(TRACE). For this study we identified 52 well-observed X- and M- class
two-ribbon flares which fit our criteria: (1) most portions of the
two ribbons are inside the field of view (FOV); (2) TRACE obtained
several images during the rise and impulsive phase, from which we
can see the two ribbons and their evolution clearly; (3) limb flares,
which make the two ribbons and their evolution unable to be seen are
not considered. Our preliminary results are: a) 87% (45 out of 52
of these flares (Type I flare) show shear change of footpoints and
ribbon separation; b) in most Type I flares, the cessation of shear
change is 1-2 minutes earlier than the end of the impulsive phase; c)
there is no obvious ribbon separation in those 7 flares (Type II flare)
which have no shear change of the conjugate footpoints.

---------------------------------------------------------
Title: Coronal Dynamics and the AIA on SDO
Authors: Golub, L.
2006SSRv..124...23G Altcode: 2007SSRv..tmp...48G
We provide a brief overview of present-day studies of inner corona
dynamics, with examples of mass ejections (CME), flares and active
region dynamics. While the names of the topics have not changed in
several decades, the internal details and the language used to express
the nature of the problem have changed considerably. We conclude with
a short discussion of the contribution to studies of coronal dynamics
to be expected from the Atmospheric Imager Assembly (AIA) on the Solar
Dynamics Observatory.

---------------------------------------------------------
Title: A statistical study of shear motion of EUV footpoints in
two-ribbon flares
Authors: Su, Y. N.; Golub, L.; van Ballegooijen, A. A.; Huang, G. L.
2006IAUS..233..409S Altcode:
We present a statistical investigation of shear motion of the EUV
footpoints in two-ribbon solar flares, using the high spatial resolution
data obtained in 1998-2005 by the Transition Region and Coronal
Explorer (TRACE). In this study we have selected 50 well-observed X-
and M- class two-ribbon flares. Our preliminary results are: a) 86%
(43 out of 50) of these flares show shear change of footpoints and
ribbon separation; b) there is no obvious ribbon separation in those
7 flares which have no shear change of the conjugate footpoints; c)
in most events, the cessation of shear change is 0-2 minutes earlier
than the end of the impulsive phase.

---------------------------------------------------------
Title: The Reconnection and Microscale (RAM) Mission in the LWS
Context
Authors: Golub, L.; Deluca, E.
2005AGUFMSH54A..02G Altcode:
Hot magnetized plasmas are ubiquitous throughout the universe. The
physics governing the dynamics of such plasmas takes place on remarkably
small spatial and temporal scales, while both the cause of and the
response to this activity occur on large spatial scales. Understanding
the dynamics, energetics, and coupling between magnetic fields and
plasmas are key focal points of research in astro-, space, and solar
physics. Studying the Sun provides unique opportunities to examine these
processes with unprecedented detail and scope unattainable for more
remote objects. Few problems have proved as resistant to solution as the
production of high-energy particles in hot magnetized plasmas. Theory
and observations indicate that both magnetic reconnection and shocks
can accelerate particles to high energies, involving small-scale
structures that ultimately affect a much larger volume. Reconnection
has been invoked to explain a wide range of explosive solar activity,
from surges to coronal mass ejections, requiring the creation and
dissipation of fine-scale currents. The Reconnection and Microscale
(RAM) Mission is focused on understanding these key processes on
the Sun, with particular emphasis on the production of high-energy
particles and radiation. RAM obtains imaging and spectroscopic
data with unprecedented resolution, and distinguishes among proposed
energy-release and particle-acceleration mechanisms by determining the
fine-scale structure of heated and cooling threads, and by observing
the detailed evolution of multithermal plasmas using high-cadence
spectroscopic imaging with broad temperature coverage. Lessons learned
will also be applicable to both laboratory and non-solar magnetoplasmas,
from the magnetosphere to active galaxies.

---------------------------------------------------------
Title: Analysis of EUV Brightenings of Solar Flares
Authors: Su, Y.; Golub, L.; van Ballegooijen, A.; Gros, M.
2005AGUFMSH13A0272S Altcode:
An X17 class (GOES soft X-ray) two-ribbon solar flare occurred on
2003 October 28. EUV observations made by the Transition Region and
Coronal Explorer (TRACE) show us that the two flare ribbons are
initially composed of several discrete bright kernels. High time
resolution hard X-ray (HXR) (E &gt;150 KeV) data were obtained by the
anticoincidence system (ACS) of the spectrometer SPI on board the ESA
INTEGRAL satellite, and 8 spikes can be seen during the impulsive
phase of the solar flare. The comparison of the evolution of EUV
bright kernels and HXR light curves shows us that individual peaks in
the HXR bursts are associated with peaks in the EUV light curves of
individual bright kernels, which suggests that the EUV kernels result
from direct energy deposition of the energetic particles accelerated
in the flare. EUV bright kernels within the flare ribbons are tracked
and identified as conjugate footpoints using a manual method. The
co-alignment of TRACE/EUV and Hα images from Big Bear Solar Observatory
(BBSO) using EIT and MDI data from SOHO allows us to obtain information
about the ribbon's underlying magnetic inversion line. We find that
the EUV conjugate footpoints start (3 minutes before the hard X-ray
onset) at a position close to, but with a large separation along,
the magnetic inversion line and evolve into straight across and far
from the inversion line during the impulsive phase. We also made a
statistical investigation of the two-ribbon flares observed by TRACE. We
find that this progressive decrease in shear of footpoints is a common
feature, which appears to indicate that the pre-flare magnetic field
configuration of this kind of flare is highly sheared close to, and
less sheared far from the magnetic inversion line.

---------------------------------------------------------
Title: The Reconnection and Microscale (RAM) probe
Authors: Golub, Leon; Bookbinder, Jay A.; DeLuca, Edward E.; Karpen,
Judith T.
2005SPIE.5901..281G Altcode:
Hot magnetized plasmas - typified by the solar corona - are
ubiquitous throughout the universe. The physics governing the
dynamics of such plasmas takes place on remarkably small spatial
and temporal scales, while both the cause activity and the response
occur on large spatial scales. Thus both high resolution and large
fields of view are needed. Observations from SMM, Yohkoh, EIT and
TRACE show that typical solar active region structures range in
temperature from 0.5 to 10 MK, and up to 40MK in flares, implying
the need for broad temperature coverage. The RAM S-T Probe consists
of a set of imaging and spectroscopic instruments that will enable
definitive studies of fundamental physical processes that govern
not only the solar atmosphere but much of the plasma universe. Few
problems in astrophysics have proved as resistant to solution as the
microphysics that results in the production of high-energy particles
in hot magnetized plasmas. Theoretical models have focused in recent
years on the various ways in which energy may be transported to the
corona, and there dissipated, through the reconnection of magnetic
fields. Theory implies that the actual dissipation of energy in the
corona occurs in spatially highly localized regions, and there is
observational support for unresolved structures with filling factors
0.01 - 0.001 in dynamic coronal events.

---------------------------------------------------------
Title: Calibration of the Solar-B x-ray optics
Authors: Cosmo, Mario L.; DeLuca, Edward E.; Golub, Leon; Austin,
Gerald K.; Chappell, Jon H.; Barbera, Marco; Bookbinder, Jay A.;
Cheimets, Peter N.; Cirtain, Jonathan; Podgorski, William A.; Davis,
William; Varisco, Salvatore; Weber, Mark A.
2005SPIE.5900...99C Altcode:
The Solar-B X-ray telescope (XRT) is a grazing-incidence modified Wolter
I X-ray telescope, of 35 cm inner diameter and 2.7 m focal length. XRT,
designed for full sun imaging over the wavelength 6-60 Angstroms, will
be the highest resolution solar X-Ray telescope ever flown. Images
will be recorded by a 2048 X 2048 back-illuminated CCD with 13.5 μm
pixels (1 arc-sec/pixel ) with full sun field of view. XRT will have
a wide temperature sensitivity in order to observe and discriminate
both the high (5-10 MK) and low temperature (1-5 MK) phenomena in
the coronal plasma. This paper presents preliminary results of the
XRT mirror calibration performed at the X-ray Calibration Facility,
NASA-MSFC, Huntsville, Alabama during January and February 2005. We
discuss the methods and the most significant results of the XRT mirror
performance, namely: characteristics of the point response function
(PSF), the encircled energy and the effective area. The mirror FWHM
is 0.8" when corrected for 1-g, finite source distance, and CCD
pixelization. With the above corrections the encircled energy at 27
μm and 1keV is 52%. The effective area is greater than 2cm2
at 0.5keV and greater than 1.7cm2 at 1.0keV.

---------------------------------------------------------
Title: Development and testing of EUV multilayer coatings for the
atmospheric imaging assembly instrument aboard the Solar Dynamics
Observatory
Authors: Soufli, Regina; Windt, David L.; Robinson, Jeff C.; Baker,
Sherry L.; Spiller, Eberhard; Dollar, Franklin J.; Aquila, Andrew L.;
Gullikson, Eric M.; Kjornrattanawanich, Benjawan; Seely, John F.;
Golub, Leon
2005SPIE.5901..173S Altcode:
We present experimental results on the development and testing of the
extreme ultraviolet (EUV) reflective multilayer coatings that will be
used in the Atmospheric Imaging Assembly (AIA) instrument. The AIA,
comprising four normal incidence telescopes, is one of three instruments
aboard the Solar Dynamics Observatory mission, part of NASA's Living
with a Star program, currently scheduled for launch in 2008. Seven
different multilayer coatings will be used, covering the wavelength
region from 93.9 to 335.4 Å.

---------------------------------------------------------
Title: Spicules, mass transfer, oscillations, and the heating of
the corona
Authors: Pasachoff, J. M.; Kozarev, K. A.; Butts, D. L.; Gangestad,
J. W.; Seaton, D. B.; de Pontieu, B.; Golub, L.; Deluca, E.; Wilhelm,
K.; Dammasch, I.
2005AGUSMSH13C..02P Altcode:
The mass moving in chromospheric spicules is enough to replace the
corona in a brief time, so understanding the dynamics of spicules
is important for understanding the support and heating of the
solar corona. We have undertaken a program involving simultaneous
high-resolution observations in various chromospheric visible lines
(H-alpha, Ca II H, and G-band, as well as Dopplergrams) using the
Swedish Solar Telescope on La Palma, ultraviolet chromospheric,
transition-region, and coronal lines (Fe IX/X 171 A, Lyman-alpha
1216 A, and continuum/C I/C IV 1600 A) using NASA's TRACE, and
ultraviolet chromospheric and transition-region lines (Si II 1533,
C IV 1548, and Ne VIII 770) using SUMER on SOHO. Our first coordinated
observing run, in May 2004, yielded a variety of images that are under
study, especially for the morphological statistics and dynamics of
spicules. The energy transfer through the chromosphere is relevant to
the overlapping investigation of coronal heating through rapid (1Hz
range) oscillations of coronal loops as observed at total eclipses
by Williams College expeditions. This research is supported by NASA
grant number NNG04GK44G to Williams College. TRACE analysis at SAO
is supported by a contract from Lockheed Martin. SOHO is a project of
international cooperation between ESA and NASA.

---------------------------------------------------------
Title: The Atmospheric Imaging Assembly (AIA) investigation for the
NASA SDO mission
Authors: Lemen, J. R.; Title, A. M.; Golub, L.
2005AGUSMSH43A..17L Altcode:
The Atmospheric Imaging Assembly (AIA) is one of three science
investigations selected for the NASA Solar Dynamics Observatory, the
first mission in NASA's Living With a Star program that is designed to
study the Sun's influence on the Earth and the nearby environment. AIA
consists of four normal incidence telescopes with multilayer coated
optics. It records solar EUV emission with high spatial resolution
(0.6 arcsec pixels) at six wavelengths from iron ions in the solar
atmosphere at temperatures between 6.3 × 105 K and 15 × 106 K:
Fe IX (171Å); Fe XII,XXIV (193Å); Fe XIV (211 Å); Fe XVI (335Å);
Fe XVIII (94Å); and Fe XX,XXIII (131Å). Other wavelength channels
enable observations of the chromosphere (He II, 304Å; C IV) and the
photosphere. Each telescope contains a 16-Mpixel CCD/camera system and
has a 41 arcmin field of view. AIA will return 8 full solar-disk images
every 10 s, producing 2.2 Tbytes/day of data. The AIA investigation is
led by PI Alan Title (LMSAL) with major participation by the Harvard
Smithsonian Astrophysical Observatory, Montana State University, and
Stanford University. The SDO mission is scheduled for launch in 2008
and will have a nominal five year mission lifetime, but will carry
resources for at least ten years of mission operations.

---------------------------------------------------------
Title: The Calibration of the Solar-B X-ray Telescope (XRT)
Authors: Golub, L.; Barbera, M.; Bookbinder, J.; Cheimets, P.; Cirtain,
J.; Cosmo, M.; Deluca, E.; Podgorski, W.; Sette, A.; Varisco, S.;
Weber, M.
2005AGUSMSP43A..01G Altcode:
The Solar-B X-ray telescope (XRT) is designed to have a wide temperature
sensitivity in order to observe and analyze both the high (5-10 MK)
and low temperature (1-5 MK) phenomena in the coronal plasma. It will
be the telescope with the highest resolution ever flown for solar
coronal studies. The telescope is designed for full Sun imaging over
the wavelength range 6-60 Angstroms. The XRT is a grazing-incidence
modified Wolter I X-ray telescope, of 35 cm inner diameter and 2.7
m focal length. The 2048 X 2048 back illuminated CCD has 13.5 Âµm
pixels, corresponding to 1 arcsecond. The filter set used in the XRT,
mounted at the telescope entrance and near the focal plane, will perform
three functions: (1) to reduce the heat load inside the telescope,
(2) to reduce the incoming visible light and (3) to provide spectral
diagnostics to determine coronal plasma temperatures. This paper
will present the results of the XRT calibration performed at the X-ray
Calibration Facility, NASA-MSFC, Huntsville, Alabama in January 2005. We
will discuss the methods and the most significant results of the XRT
performance, namely: imaging properties, encircled energy, the point
response function and the effective area in the 0.2-2 keV energy range.

---------------------------------------------------------
Title: EUV Observations of Active Region Dynamics
Authors: Deluca, E. E.; Cirtain, J. W.; del Zanna, G.; Mason, H. E.;
Martens, P. C.; Schmelz, J.; Golub, L.
2005AGUSMSP33A..03D Altcode:
Data collected during SoHO JOP 146, in collaboration with TRACE, is
used to investigate the physical characteristics of coronal active
region loops as a function of time and position along and across
loop structures. These data include TRACE images in all three EUV
passbands, and simultaneous CDS spectroscopic observations. Preliminary
measurements of the loop temperature both along the loop half-length
and loop cross-section are presented as a function of time. We will
show the temperature and density profiles of several structures as a
function of position, show changes in temperature and density with time
and characterize the coronal background emission. Questions raised
by these results will be greatly advanced with the high resolution
spectra available from the EIS on Solar-B.

---------------------------------------------------------
Title: The black-drop effect explained
Authors: Pasachoff, Jay M.; Schneider, Glenn; Golub, Leon
2005tvnv.conf..242P Altcode: 2005IAUCo.196..242P
The black-drop effect bedeviled attempts to determine the Astronomical
Unit from the time of the transit of Venus of 1761, until dynamical
determinations of the AU obviated the need for transit measurements. By
studying the 1999 transit of Mercury, using observations taken from
space with NASA's Transition Region and Coronal Explorer (TRACE), we
have fully explained Mercury's black-drop effect, with contributions
from not only the telescope's point-spread function but also the solar
limb darkening. Since Mercury has no atmosphere, we have thus verified
the previous understanding, often overlooked, that the black-drop effect
does not necessarily correspond to the detection of an atmosphere. We
continued our studies with observations of the 2004 transit of Venus
with the TRACE spacecraft in orbit and with ground-based imagery from
Thessaloniki, Greece. We report on preliminary reduction of those
data; see http://www.transitofvenus.info for updated results. Such
studies are expected to contribute to the understanding of transits
of exoplanets. Though the determination of the Astronomical Unit from
studies of transit of Venus has been undertaken only rarely, it was
for centuries expected to be the best method. The recent 8 June 2004
transit of Venus provided an exceptionally rare opportunity to study
such a transit and to determine how modern studies can explain the
limitations of the historical observations.

---------------------------------------------------------
Title: Space Studies of the Black-Drop Effect at a Mercury Transit
Authors: Schneider, Glenn; Pasachoff, Jay M.; Golub, Leon
2005HiA....13...70S Altcode:
The accuracy with which the Astronomical Unit was known has been
historically limited by the ""black drop"" effect observed during
Venus's rare transits. It is often mistakenly attributed to Venus's
atmosphere. We report on observations taken outside the Earth's
atmosphere of the 1999 and 2003 transits of Mercury with the NASA
solar satellite known as the Transition Region and Coronal Explorer
(TRACE). Though there was no contribution from the atmosphere of Mercury
or the Earth nevertheless a faint black-drop effect was detected. We
discuss and model the images showing the sources of the black-drop
effect. The techniques we discuss are applicable to ground-based and
space-based observations of the 8 June 2004 and 5-6 June 2012 transits
of Venus.

---------------------------------------------------------
Title: Science of the X-ray Sun: The X-ray telescope on Solar-B
Authors: DeLuca, E. E.; Weber, M. A.; Sette, A. L.; Golub, L.;
Shibasaki, K.; Sakao, T.; Kano, R.
2005AdSpR..36.1489D Altcode:
The X-Ray Telescope (XRT) on Solar-B is designed to provide high
resolution, high cadence observations of the X-ray corona through
a wide range of filters. The XRT science team has identified four
general problems in coronal physics as the primary science goals for our
instrument. Each of these goals will require collaborative observations
from the other Solar-B instruments: EUV Imaging Spectrograph (EIS)
and Solar Optical Telescope Focal Plane Package (SOT). We will discuss
the science goals and observations needed to address those goals.

---------------------------------------------------------
Title: Differential Emission Measure Reconstruction with the SolarB
X-Ray Telescope
Authors: Golub, L.; Deluca, E. E.; Sette, A.; Weber, M.
2004ASPC..325..217G Altcode:
Two of the main considerations in the design of the SolarB X-Ray
Telescope are temperature coverage and discrimination. We describe how
these factors enter into the design of XRT, as well as the methods
we have developed for producing estimates of emission measures. We
analyze model DEMs to evaluate our ability to reconstruct DEMs.

---------------------------------------------------------
Title: SolarB X-Ray Telescope (XRT)
Authors: Kano, R.; Hara, H.; Shimojo, M.; Tsuneta, S.; Sakao, T.;
Matsuzaki, K.; Kosugi, T.; Golub, L.; Deluca, E. E.; Bookbinder,
J. A.; Cheimets, P.; Owens, J. K.; Hill, L. D.
2004ASPC..325...15K Altcode:
The Soft X-ray Telescope (XRT) aboard SolarB is a grazing incidence
X-ray telescope equipped with 2k × 2k CCD. XRT has 1 arcsec resolution
with wide field-of-view of 34 × 34 arcmin. It is sensitive to
&lt;1 MK to 30 MK, allowing us to obtain TRACE-like low temperature
images as well. Co-alignment with SOT and EIS is realized through
the XRT visible light telescope and with temperature overlap with
EIS. Spacecraft mission data processor (MDP) controls XRT through
the sequence tables with versatile autonomous functions such as
exposure control, region-of-interest tracking, flare detection and
flare location identification. Data are compressed either with DPCM or
JPEG, depending on the purpose. This results in higher cadence and/or
wider field-of-view for given telemetry bandwidth. With focus adjust
mechanism, higher resolution of Gaussian focus may be available on-axis.

---------------------------------------------------------
Title: Focal plane CCD camera for the X-Ray Telescope (XRT) aboard
SOLAR-B
Authors: Sakao, Taro; Kano, Ryouhei; Hara, Hirohisa; Matsuzaki,
Keiichi; Shimojo, Masumi; Tsuneta, Saku; Kosugi, Takeo; Shibasaki,
Kiyoto; Kumagai, Kazuyoshi; Sawa, Masaki; Tamura, Tomonori; Iwamura,
Satoru; Nakano, Mitsuhiko; Du, Zhangong; Hiyoshi, Kenji; Horii,
Michihiro; Golub, Leon; Bookbinder, Jay A.; Cheimets, Peter C.; Hill,
Lawrence D.; Owens, Jerry K.
2004SPIE.5487.1189S Altcode:
We present scientific as well as engineering overview of the X-Ray
Telescope (XRT) aboard the Japanese Solar-B mission to be launched in
2006, with emphasis on the focal plane CCD camera that employs a 2k
x 2k back-thinned CCD. Characterization activities for the flight CCD
camera made at the National Astronomical Observatory of Japan (NAOJ)
are discussed in detail with some of the results presented.

---------------------------------------------------------
Title: Calibration of the XRT-SOLARB flight filters at the XACT
facility of INAF-OAPA
Authors: Barbera, Marco; Artale, Maria Antonella; Candia, Roberto;
Collura, Alfonso; Lullo, Giuseppe; Peres, Giovanni; Perinati, Emanuele;
Varisco, Salvatore; Bookbinder, J. A.; Cheimets, Peter N.; Cosmo,
Mario L.; DeLuca, Edward E.; Golub, Leon; Weber, Mark A.
2004SPIE.5488..423B Altcode:
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite
SOLAR-B (launch in 2006) aimed at providing full Sun field of view at ~
1.5" angular resolution, will be equipped with two wheels of focal-plane
filters to select spectral features of X-ray emission from the Solar
corona, and a front-end filter to significantly reduce the visible
light contamination. We present the results of the X-ray calibrations
of the XRT flight filters performed at the X-ray Astronomy Calibration
and Testing (XACT) facility of INAF-OAPA. We describe the instrumental
set-up, the adopted measurement technique, and present the transmission
vs. energy and position measurements.

---------------------------------------------------------
Title: Calibration of the XRT-SOLARB flat mirror samples at the XACT
Facility of INAF-OAPA
Authors: Artale, Maria Antonella; Barbera, Marco; Collura, Alfonso;
Di Cicca, Gaspare; Peres, Giovanni; Varisco, Salvatore; Bookbinder,
J. A.; Cheimets, Peter N.; Cosmo, Mario L.; DeLuca, Edward E.; Golub,
Leon; Weber, Mark A.
2004SPIE.5488..440A Altcode:
The X-Ray Telescope (XRT) experiment on-board the Japanese satellite
SOLAR-B (launch in 2006) is equipped with a modified Wolter I grazing
incidence X-ray telescope (focal length 2700 mm) to image the full Sun
at ~ 1.5" angular resolution onto a 2048 x 2048 back illuminated CCD
focal plane detector. The X-ray telescope consisting of one single
reflecting shell is coated with ion beam sputtered Iridium over a
binding layer of Chromium to provide nearly 5 square centimetres
effective area at 60 Å. We present preliminary results of X-ray
calibrations of the XRT flat mirror samples performed at the X-ray
Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. We
describe the instrumental set-up, the adopted measurement technique,
and present the measured reflectivity vs. angle of incidence at few
energies.

---------------------------------------------------------
Title: The August 11th, 1999 CME
Authors: Koutchmy, S.; Baudin, F.; Bocchialini, K.; Daniel, J. -Y.;
Delaboudinière, J. -P.; Golub, L.; Lamy, P.; Adjabshirizadeh, A.
2004A&A...420..709K Altcode:
We present here a set of observations, space borne and ground based,
at different wavelengths, of the solar corona at and after the time of
the total solar eclipse of August 11{th}. It is used to consider some
unusual features of the coronal dynamics related to a limb Coronal Mass
Ejection (CME) observed after the total eclipse. The complementary
aspect of simultaneous ground-based and space-borne observations
of the corona is used to produce an accurate composite image of the
White Light (W-L) corona before the CME. A high arch system (possibly
a dome-like structure, with large cavities inside but without a cusp
further out) which appeared on the eclipse W-L images, is suggested to
be a large-scale precursor of the CME, well preceding the eruption of
the top part of the brightest prominence recorded in W-L. This bright
prominence is shown as a filament in absorption using the Transition
Region And Corona Explorer (TRACE) images taken in different coronal
lines. The analysis of the images of the Large Angle and Spectrometric
Coronograph (LASCO) on board the Solar and Heliospheric Observatory
(SoHO), showing the progression of the CME, is discussed in an attempt
to make a connection with the surface event. A SoHO-EIT (Extreme
UV Imager Telescope) image sequence details the prominence eruption
and shows the sudden heating processes of the ejected parts. We found
that there is no reason to assume that the huge cavity is significantly
destabilised well before the eruption of the upper part of the low-lying
bright twisted filament which coincides with the position of one of
the legs of the high arch. Observations are still compatible with the
assumption of both the break-out model and of the flux rope erupting
model as a result of a shear or of an increasing poloıdal magnetic
flux from below. We stress the possible role of buoyancy of the giant
cavity as a destabilizing factor leading to the CME, noticing that some
motion of coronal material back toward the surface can be seen during at
least the first phase of the CME, from both EIT and LASCO observations.

---------------------------------------------------------
Title: Pre-Conditioning Optmization Methods and Display for Mega-Pixel
DEM Reconstructions
Authors: Sette, A. L.; DeLuca, E. E.; Weber, M. A.; Golub, L.
2004AAS...204.6904S Altcode: 2004BAAS...36R.794S
The Atmospheric Imaging Assembly (AIA) for the Solar Dynamics
Observatory will provide an unprecedented rate of mega-pixel solar
corona data. This hastens the need for faster differential emission
measure (DEM) reconstruction methods, as well as scientifically
useful ways of displaying this information for mega-pixel datasets. We
investigate pre-conditioning methods, which optimize DEM reconstruction
by making an informed initial DEM guess that takes advantage of the
sharing of DEM information among the pixels in an image. In addition,
we evaluate the effectiveness of different DEM image display options,
including single temperature emission maps and time-progression DEM
movies. This work is supported under contract SP02D4301R to the
Lockheed Martin Corp.

---------------------------------------------------------
Title: The Atmospheric Imaging Assembly and Temperature Diagnostics
Authors: Weber, M. A.; Caldwell, D.; Deluca, E. E.; Golub, L.; Sette,
A. L.
2004AAS...204.6906W Altcode: 2004BAAS...36..795W
The Atmospheric Imaging Assembly (AIA) will be one of the instruments
on the Solar Dynamics Observatory (SDO). It will image the solar
transition region and corona in multiple EUV and UV wavelengths
simultaneously, using four aligned telescopes. Hence, AIA will be
capable of high-cadence, spatially resolved temperature discrimination
of solar plasmas. We discuss the design of AIA, with focus on its
ability for temperature diagnostics. We consider different methods for
reconstruction of differential emission measures, since this will be
one of the more important data products. This work is supported
under contract SP02D4301R to the Lockheed Martin Corp.

---------------------------------------------------------
Title: Science with the Solar-B X-Ray Telescope
Authors: Deluca, E. E.; Weber, M. A.; Golub, L.
2004AAS...204.6905D Altcode: 2004BAAS...36Q.795D
The Solar-B mission will launch in 2006 with three telescopes:
a high resolution visible light telescope feeding filtergraph and
spectropolarimeter focal plane instruments, a grazing incidence X-Ray
telescope and an EUV spectrograph. This combination of instruments
will provide detailed information on Active Region evolution, heating,
connectivity and dynamics. The X-Ray telescope on Solar-B will be
sensitive to emission from 1-50MK. Focal plane filters will allow us
to follow the evolution of the bulk of the coronal plasma. This poster
will describe the core science that will be done by XRT together with
EIS and SOT. Joint observing programs will also be discussed.

---------------------------------------------------------
Title: TRACE observations of the 15 November 1999 transit of Mercury
and the Black Drop effect: considerations for the 2004 transit
of Venus
Authors: Schneider, Glenn; Pasachoff, Jay M.; Golub, Leon
2004Icar..168..249S Altcode:
Historically, the visual manifestation of the "Black Drop effect," the
appearance of a band linking the solar limb to the disk of a transiting
planet near the point of internal tangency, had limited the accuracy of
the determination of the Astronomical Unit and the scale of the Solar
System in the 18th and 19th centuries. This problem was misunderstood
in the case of Venus during its rare transits due to the presence of
its atmosphere. We report on observations of the 15 November 1999
transit of Mercury obtained, without the degrading effects of the
Earth's atmosphere, with the Transition Region and Coronal Explorer
spacecraft. In spite of the telescope's location beyond the Earth's
atmosphere, and the absence of a significant mercurian atmosphere, a
faint Black Drop effect was detected. After calibration and removal of,
or compensation for, both internal and external systematic effects,
the only radially directed brightness anisotropies found resulted
from the convolution of the instrumental point-spread function with
the solar limb-darkened, back-lit, illumination function. We discuss
these effects in light of earlier ground-based observations of transits
of Mercury and of Venus (also including the effects of atmospheric
"seeing") to explain the historical basis for the Black Drop effect. The
methodologies we outline here for improving upon transit imagery are
applicable to ground-based (adaptive optics augmented) and space-based
observations of the 8 June 2004 and 5-6 June 2012 transits of Venus,
providing a path to achieving high-precision measurements at and near
the instants of internal limb tangencies.

---------------------------------------------------------
Title: EUV multilayers for solar physics
Authors: Windt, David L.; Donguy, S.; Seely, John F.;
Kjornrattanawanich, Benjawan; Gullikson, Eric M.; Walton, C. C.;
Golub, L.; DeLuca, E.
2004SPIE.5168....1W Altcode:
We present an overview of currently available EUV multilayer coatings
that can be used for the construction of solar physics instrumentation
utilizing normal-incidence optics. We describe the performance of
a variety of Si-based multilayers, including Si/B4C and
new Si/SiC films that provide improved performance in the wavelength
range from 25 n 35 nm, as well as traditional Si/Mo multilayers,
including broad-band coatings recently developed for the Solar-B/EIS
instrument. We also outline prospects for operation at both longer and
shorter EUV wavelengths, and also the potential of ultra-short-period
multilayers that work near normal incidence in the soft X-ray region.

---------------------------------------------------------
Title: New dimensions in coronal studies from the XRT on Solar-B
Authors: Golub, L.
2004cosp...35.4419G Altcode: 2004cosp.meet.4419G
The X-ray Telescope (XRT) on Solar-B will be the highest resolution
telescope ever flown in space for solar coronal observations. It
will have full Sun coverage with 1.0 arcsec pixel resolution, and
extended low and high temperature coverage. The onboard data storage
and high telemetry rate will provide excellent image cadence and also
the ability to observe in flare mode, so that high cadence pre-flare
data can be retained when a flare occurs. The full range of coronal
targets, from coronal holes and bright points, to active regions and
flares up to X-level in brightness can be observed. The polar orbit
will permit long periods of continuous coverage for the first time in
a soft x-ray imaging instrument.

---------------------------------------------------------
Title: Temperature diagnostics with multichannel imaging telescopes
Authors: Weber, M. A.; Deluca, E. E.; Golub, L.; Sette, A. L.
2004IAUS..223..321W Altcode: 2005IAUS..223..321W
Modern solar telescope design in the EUV to x-ray range is now capable
of producing large images in multiple channels at rapid cadences, with
high spatial and temperature resolution. We discuss reconstruction
of differential emission measures for solar coronal plasma using two
state-of-the-art instruments: the X-Ray Telescope on Solar-B, and the
Atmospheric Imaging Assembly on the Solar Dynamics Observatory. We
discuss the relative merits of iteration and direct inversion methods
for determining DEM(T). We also consider strategies for automating and
visualizing DEM maps, given the high data rates that these instruments
will produce. We touch on the scientific potential of high-cadence,
spatially resolved DEM data products.

---------------------------------------------------------
Title: Explanation of the Black-Drop Effect at Transits of Mercury
and the Forthcoming Transit of Venus
Authors: Pasachoff, J. M.; Schneider, G.; Golub, L.
2003AAS...203.0104P Altcode: 2003BAAS...35.1202P
We used the observations of the transits of Mercury of 1999 and 2003
taken with NASA's Transition Region and Coronal Explorer (TRACE) solar
spacecraft. For the 1999 Mercury transit, for which data were acquired
with the highest digital fidelity available for TRACE, we detected a
black-drop effect, in spite of the facts that we were observing from
outside the Earth's atmosphere and that Mercury has no significant
atmosphere. We were able to show that the Mercury black-drop effect
comes from a convolution of the instrument's point-spread function and
the solar limb darkening. By implication, we should be able to explain
Venus's black-drop effect in a similar way. It has long been known that
Venus's black-drop effect is too large to come from Venus's atmosphere.

---------------------------------------------------------
Title: Solar observation from space
Authors: Golub, Leon
2003RScI...74.4583G Altcode:
Solar observations are carried out in space when necessary for technical
reasons, such as detection of wavelengths that do not reach the ground,
or to provide observing conditions that are difficult or impossible to
achieve on the ground. Examples in the first category are observations
at far ultraviolet or soft x-ray wavelengths and direct detection
of solar wind particles; in the latter are precise measurements of
variations in the solar luminosity and stereo observations of coronal
mass ejections. This article samples the wide variety of techniques
presently being used to study the Sun. We begin with an overview of
the observational problem presented by the particular scientific
questions involved in improving our understanding of the Sun, and
of solar activity in particular. We then discuss the need for and
advantages of observations from space, and give examples of scientific
objectives which can only be met by such observations. We then describe
in detail some representative examples of space missions and specific
space-based experiments for solar studies.

---------------------------------------------------------
Title: Book review: The century of space science / Johan
A. M. Bleeker, Johannes Geiss, Martin C. E. Huber (eds.), Kluwer
Academic Publ., Dordrecht, The Netherlands, XIV + 1846 pp., 2001,
ISBN 0-7923-7196-8.
Authors: Golub, Leon
2003JHA....34..461G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical Morphologies of Flares Associated with the Two
Types of Solar Coronal Mass Ejections
Authors: Zhang, Mei; Golub, Leon
2003ApJ...595.1251Z Altcode:
In this paper we study the high-cadence TRACE observations of a sample
of 28 X- and M-class flares, with particular focus on the relation
between flare morphology and the two types (fast and slow) of solar
coronal mass ejections (CMEs). Among the 28 flares studied, 10 are
associated with fast CMEs, 10 are associated with slow CMEs, and 8 are
loosely associated with a CME. We find that flares associated with fast
and slow CMEs show different morphologies as groups. While all flares
associated with fast CMEs show clear footpoint-separating, two-ribbon
brightenings during the flare, this feature is less often seen in
flares associated with slow CMEs or flares without CMEs. Meanwhile,
while flares associated with slow CMEs sometimes show tubular emission
structures during the flare, this feature is not found in our sample
of flares associated with fast CMEs. This observational result suggests
that the morphologies of flares, and hence possibly the magnetic field
topologies, are different for events associated with fast and with
slow CMEs.

---------------------------------------------------------
Title: Space Studies of the Black-Drop Effect at a Mercury Transit
Authors: Schneider, G.; Pasachoff, J. M.; Golub, L.
2003astro.ph.10379S Altcode:
Transits of Mercury and Venus across the face of the Sun are rare. The
20th century had 15 transits of Mercury and the 21st century will have
14, the two most recent occuring on 15 November 1999 and 7 May 2003. We
report on our observations and analyses of a black-drop effect at the
1999 and 2003 transits of Mercury seen in high spatial resolution
optical imaging with NASA's Transition Region and Coronal Explorer
(TRACE) spacecraft. We have separated the primary contributors to this
effect, solar limb darkening and broadening due to the instrumental
point spread function, for the 1999 event. The observations are
important for understanding historical observations of transits
of Venus, which in the 18th and 19th centuries were basic for the
determination of the scale of the solar system. Our observations
are in preparation for the 8 June 2004 transit of Venus, the first
to occur since 1882. Only five transits of Venus have ever been seen
-- in 1639, 1761, 1769, 1874, and 1882. These events occur in pairs,
whose members are separated by 8 years, with an interval between pairs
of 105 or 122 years. Nobody alive has ever seen a transit of Venus.

---------------------------------------------------------
Title: Constraints on Active Region Coronal Heating
Authors: Antiochos, S. K.; Karpen, J. T.; DeLuca, E. E.; Golub, L.;
Hamilton, P.
2003ApJ...590..547A Altcode:
We derive constraints on the time variability of coronal heating from
observations of the so-called active region moss by the Transition
Region and Coronal Explorer (TRACE). The moss is believed to be due to
million-degree emission from the transition regions at the footpoints
of coronal loops whose maximum temperatures are several million
degrees. The two key results from the TRACE observations discussed in
this paper are that in the moss regions one generally sees only moss,
not million-degree loops, and that the moss emission exhibits only weak
intensity variations, ~10% over periods of hours. TRACE movies showing
these results are presented. We demonstrate, using both analytic and
numerical calculations, that the lack of observable million-degree
loops in the moss regions places severe constraints on the possible
time variability of coronal heating in the loops overlying the moss. In
particular, the heating in the hot moss loops cannot be truly flarelike
with a sharp cutoff, but instead must be quasi-steady to an excellent
approximation. Furthermore, the lack of significant variations in
the moss intensity implies that the heating magnitude is only weakly
varying. The implications of these conclusions for coronal heating
models will be discussed.

---------------------------------------------------------
Title: Propagating EUV disturbances in the Solar corona:
Two-wavelength observations
Authors: King, D. B.; Nakariakov, V. M.; Deluca, E. E.; Golub, L.;
McClements, K. G.
2003A&A...404L...1K Altcode:
Quasi-periodic EUV disturbances simultaneously observed in 171 Å and
195 Å TRACE bandpasses propagating outwardly in a fan-like magnetic
structure of a coronal active region are analysed. Time series of
disturbances observed in the different bandpasses have a relatively
high correlation coefficient (up to about 0.7). The correlation has
a tendency to decrease with distance along the structure: this is
consistent with an interpretation of the disturbances in terms of
parallel-propagating slow magnetoacoustic waves. The wavelet analysis
does not show a significant difference between waves observed in
different bandpasses. Periodic patterns of two distinct periods: 2-3 min
and 5-8 min are detected in both bandpasses, existing simultaneously
and at the same distance along the loop, suggesting the nonlinear
generation of the second harmonics.

---------------------------------------------------------
Title: The High Resolution Imager on the Reconnection and Microscale
(RAM) Mission
Authors: Bookbinder, J. A.; DeLuca, E. E.; Golub, L.; Weber, M.;
Karpen, J. T.
2003SPD....34.2404B Altcode: 2003BAAS...35..853B
Hot, magnetized plasmas such as the solar corona have the property that
much of the physics governing its activity takes place on remarkably
small spatial and temporal scales, while the response to this activity
occurs on large scales. Future progress on the challenging solar
physics issues of eruptive flares, coronal heating and the initial of
the solar wind requires observations on spatial and temporal scales
relevant to the observable signatures of the underlying physical
processes. These spatial and temporal domains - in the relevant
temperature regimes - have been heretofore inaccessible to direct
observations from Earth, with the result that theoretical efforts have
relied heavily on extrapolations from more accessible regimes. The
RAM Solar-Terrestrial Probe consists of a set of carefully selected
imaging and spectroscopic instruments that enable definitive studies of
the dynamics and energetics of the solar corona. We present an overview
of the synergism inherent in the RAM instrument suite, with emphasis
on the rationale for, and the capability of, its high-resolution imager.

---------------------------------------------------------
Title: The Reconnection And Microscale (RAM) Solar-Terrestrial Probe
Authors: Bookbinder, Jay A.; DeLuca, Edward; Cheimets, Peter; Golub,
Leon; Hassler, Donald M.; Korendyke, Clarence M.; Glenn, Paul E.;
Silver, Eric H.
2003SPIE.4853..436B Altcode:
A hot, magnetized plasma such as the solar corona has the property that
much of the physics governing its activity takes place on remarkably
small spatial and temporal scales, while the response to this activity
occurs on large scales. Observations from SMM, TRACE, SOHO and Yohkoh
have shown that typical solar active regions have loops ranging in
temperature from 0.5 to 10 MK, and flares up to 40MK. The spatial
and temporal domains involved have been heretofore inaccessible to
direct observations from Earth, so that theory has relied heavily on
extrapolations from more accessible regimes, and on speculation. The
RAM Solar-Terrestrial Probe consists of a set of carefully selected
imaging and spectroscopic instruments that enable definitive studies
of the dynamics and energetics of the solar corona.

---------------------------------------------------------
Title: Space Studies of the Black Drop Effect at a Mercury Transit
Authors: Pasachoff, Jay M.; Schneider, Glenn; Golub, Leon
2003IAUJD...2E...5P Altcode:
The accuracy with which the Astronomical Unit was known has been
historically limited by the ""black drop"" effect observed during
Venus's rare transits. It is often mistakenly attributed to Venus's
atmosphere. We report on observations taken outside the Earth's
atmosphere of the 1999 and 2003 transits of Mercury with the NASA
solar satellite known as the Transition Region and Coronal Explorer
(TRACE). Though there was no contribution from the atmosphere of Mercury
or the Earth nevertheless a faint black-drop effect was detected. We
discuss and model the images showing the sources of the black-drop
effect. The techniques we discuss are applicable to ground-based and
space-based observations of the 8 June 2004 and 5-6 June 2012 transits
of Venus.

---------------------------------------------------------
Title: The Timing of Flares Associated with the Two Dynamical Types
of Solar Coronal Mass Ejections
Authors: Zhang, M.; Golub, L.; DeLuca, E.; Burkepile, J.
2002ApJ...574L..97Z Altcode:
In this Letter, we consider a sample of Transition Region and Coronal
Explorer flare-associated solar coronal mass ejections (CMEs) and study
the timing behavior of the flares associated with fast or slow CMEs. We
find that flares associated with fast CMEs tend to happen within half
an hour of the CME onsets, while the timing of flares associated with
slow CMEs is only loosely related to the CME onsets. This suggests that
the occurrence of flares may be integral to the early development of
fast CMEs but is not crucial for slow CMEs. This observational result
supports a recent qualitative theory of the initiation and expulsion
mechanism of the two dynamical types of CMEs.

---------------------------------------------------------
Title: Active Region Loop Heating
Authors: Antiochos, S. K.; Karpen, J. T.; DeLuca, E. E.; Golub, L.;
Hamilton, P.
2002AAS...200.1606A Altcode: 2002BAAS...34..668A
A long-standing unresolved question in solar physics is whether the
heating in coronal loops is steady or impulsive. X-ray observations
of high-temperature loops (T &gt; 2 x 106 K) tend to
show quasi-steady structures, (evolution slow compared to cooling
time scales), whereas theoretical models strongly favor impulsive
heating. We present simulations of impulsively heated loops using
our adaptive-mesh-refinement code ARGOS, and compare the results with
TRACE observations of the transition regions of high-temperature active
region loops. From this comparison, we deduce that the heating in the
core of active regions is quasi-steady rather than impulsive. These
results pose a formidable challenge to developing theoretical models
for the heating. This work was supported in part by NASA and ONR.

---------------------------------------------------------
Title: The Reconnection and Microscale (RAM) Mission
Authors: Bookbinder, J. A.; DeLuca, E. E.; Golub, L.
2002AAS...200.5609B Altcode: 2002BAAS...34Q.736B
Hot magnetized plasmas - typified by the solar corona - are ubiquitous
throughout the universe. The physics governing the dynamics of
such plasmas takes place on remarkably small spatial and temporal
scales, while both the cause activity and the response occur on large
spatial scales. Thus both high resolution and large fields of view are
needed. Observations show that typical solar active region structures
range in temperature from 0.5 to 10 MK, and up to 40 MK in flares,
implying the need for broad temperature coverage. The RAM mission is
designed to meet the observational requirements of the next generation
Solar observatory; we present an overview of the proposed ST-Probe
class mission concept, instrument complement, and technology status. We
emphasize the capabilities and status of the instrument suite that
is proposed: a set of imaging and spectroscopic instruments that will
enable definitive studies of fundamental physical processes that govern
not only the solar atmosphere but much of the plasma universe. The
imaging instruments on RAM combine extremely high spatial resolution
in the corona ( ~10 km) with intermediate scale ( ~70 km) large FOV
observations at several complementary passbands/temperatures. The
spectroscopic instruments offer high resolution ( ~70 km spatial,
~5 km/s velocity) imaging EUV spectroscopy and a photon counting
imaging X-ray micro-calorimeter array offers ( ~700 km, 2 eV energy,
~10 msec time) over a bandpass from 0.2 to &gt;40 keV.

---------------------------------------------------------
Title: Science Objectives of the Reconnection and Micrcoscale (RAM)
Solar-Terrestrial Probe
Authors: DeLuca, E. E.; Bookbinder, J.; Golub, L.
2002AAS...200.8801D Altcode: 2002BAAS...34..789D
The RAM mission is designed to address fundamental questions related
to the origin and dynamics of hot magnetized plasmas throughout
the universe. Observations of the solar corona demonstrate that
the important physical processes take place on small spatial
and temporal scales, while the energy driving these processes is
stored on large scales, and the response can affect the global
structure of the corona. In this talk we discuss the theoretical
and observational evidence for the existence of small-scale coronal
structures, and outline the observational requirements to answer the
following fundamental questions that apply to all coronal plasmas:
(1) What are the conditions that lead to magnetic reconnection? (2)
What micro-scale instabilities lead to global effects? (3) Where are
the regions of particle acceleration? (4) Where are the reconnection
regions and what is their topology? A companion poster will present the
baseline instrument complement that will achieve these observational
requirements.

---------------------------------------------------------
Title: A photometric imaging solar telescope, tunable in the extreme
ultraviolet, utilizing multilayer x-ray optics
Authors: Golub, L.; Deluca, E.; Hamilton, P.; Nystrom, G.; Windt,
D. L.; Schmidt, W. K. H.; Dannenberg, A.
2002RScI...73.1908G Altcode:
We present a new instrument for space-based observational solar physics,
recently flown successfully on a sounding rocket, designed to provide
high spatial resolution, time-resolved images of the solar corona at
specific wavelengths in the extreme ultraviolet (XUV). The primary
instrument employs multilayer x-ray mirrors in a novel geometry that
affords quasi-monochromatic imaging at wavelengths tunable continuously
over the spectral range from 17.1 to 21.1 nm. The secondary instrument
also uses multilayer x-ray mirrors to provide high-resolution imaging
at three fixed XUV wavelength bands. Both instruments use charge
coupled device detectors and thin A1 filters for rejection of unwanted
wavelengths. We describe the design, construction, and performance of
the instrument and discuss prospects for the future.

---------------------------------------------------------
Title: A New View of the Solar Corona from TRACE
Authors: Golub, Leon
2002smra.progE...5G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Steady Flows Detected in Extreme-Ultraviolet Loops
Authors: Winebarger, Amy R.; Warren, Harry; van Ballegooijen, Adriaan;
DeLuca, Edward E.; Golub, Leon
2002ApJ...567L..89W Altcode:
Recent Transition Region and Coronal Explorer (TRACE) observations have
detected a class of active region loops whose physical properties are
inconsistent with previous hydrostatic loop models. In this Letter we
present the first co-aligned TRACE and the Solar Ultraviolet Measurement
of Emitted Radiation (SUMER) observations of these loops. Although these
loops appear static in the TRACE images, SUMER detects line-of-sight
flows along the loops of up to 40 km s-1. The presence
of flows could imply an asymmetric heating function; such a heating
function would be expected for heating that is proportional to
(often asymmetric) footpoint field strength. We compare a steady flow
solution resulting from an asymmetric heating function to a static
solution resulting from a uniform heating function in a hypothetical
coronal loop. We find that the characteristics associated with the
asymmetrically heated loop better compare with the characteristics of
the loops observed in the TRACE data.

---------------------------------------------------------
Title: Nearest star: The surprising science of our Sun
Authors: Golub, Leon; Pasachoff, Jay M.; O'Connell, James
2002PhTea..40..127G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Imaging solar coronal structures with TRACE
Authors: Golub, L.
2002cosp...34E.131G Altcode: 2002cosp.meetE.131G
The Transition Region and Coronal Explorer (TRACE) is revealing
previously unknown structure and dynamics in the solar outer
atmosphere. Extremely fine threads of emission are ubiquitous, and they
are mostly inconsistent with the density and temperature structure
predicted by standard hydrostatic models of closed loops. Unequal
heating at the footpoints induces flows in the corona which in turn
accounts for the observed properties of these structures. Detailed
comparison of the footpoints with high resolution surface magnetic field
observations indicates that the hot coronal plasma is not confined by
the coronal magnetic field, although it is constrained by the field.

---------------------------------------------------------
Title: Magnetic structure and reconnection of x-ray bright points
in the solar corona
Authors: Brown, D. S.; Parnell, C. E.; DeLuca, E. E.; McMullen, R. A.;
Golub, L.; Priest, E. R.
2002AdSpR..29.1093B Altcode:
The three-dimensional magnetic topology of the solar corona is
incredibly complex and its effect on the nature of 3D reconnection is
profound. We study the supposedly simple topology of a small scale X-ray
bright point observed by TRACE and SOHO/MDI, and how it is driven by
reconnection when it forms and during the early stages of its lifetime.

---------------------------------------------------------
Title: High resolution coronal imaging with multilayers
Authors: Golub, L.; Hassler, D. M.
2002AdSpR..29.1999G Altcode:
Since the 1960s, when on-disk coronal imaging became possible, progress
in the field has consisted largely in improving the spectral spatial
and temporal resolution of the observations. With the development of
normal-incidence, soft X-ray and XUV multilayer optics in the 1980s,
a dramatic improvement in the first two of these occurred, and with
the development of better detectors the temporal resolution (along
with the sensitivity) also improved. In this paper we discuss recent
results from The Transition Region and Coronal Explorer ( TRACE),
which is providing observations of the solar outer atmosphere with
unprecedented spatial and temporal resolution. The new views of coronal
structure and dynamics being obtained indicate that: (i) the corona
is filled with flows of both hot and cool material, (ii) instead of
"loops," the basic coronal structures are threads, and (iii) threads
of hot plasma appear to form as parallel bundles on surfaces, which may
correspond to dissipation at quasi-separatrix layers. We conclude with a
discussion of the possible next generation of high resolution missions.

---------------------------------------------------------
Title: On the Time Variability of Coronal Heating
Authors: Antiochos, S. K.; Karpen, J. T.; DeLuca, E. E.; Golub, L.;
Hamilton, P.
2001AGUFMSH11A0690A Altcode:
We derive constraints on the time variability of coronal heating from
observations of the so-called active-region moss by the Transition
and Coronal Explorer (TRACE). The moss is believed to be due to
million-degree emission from the transition regions at the footpoints
of coronal loops whose maximum temperatures are several million
degrees. The key point of the TRACE observations is that in the
moss regions one generally sees only moss, and not million degree
loops. TRACE movies showing this result will be presented. We will
demonstrate using both analytic and numerical calculations, that the
lack of observable million-degree loops in the moss regions places
severe constraints on the possible time variability of coronal heating
in the loops overlying the moss. In particular, the heating in the hot
moss loops cannot be truly flare-like with a sharp cutoff, but instead,
must be quasi-steady to an excellent approximation. The implications
of this result for coronal heating models will be discussed. This work
was supported in part by NASA and ONR

---------------------------------------------------------
Title: Impulsive Events and Coronal Loop Cooling Observed with TRACE
Authors: Seaton, D. B.; DeLuca, E. E.; Golub, L.; Reeves, K. K.;
Winebarger, A. R.; Gallagher, P. T.
2001AGUFMSH11A0705S Altcode:
Nearly every active region imaged by TRACE contains sporadic
brightenings in coronal loops. Many of these ubiquitous, short-lived
events appear nearly simultaneously in the Fe IX/X (log T
e≈ 6.0) and the C IV channel (log T≈ 5.0); hence, we interpret
them as the rapid cooling of a multifilament loops. A particularly good
example of such an event was observed on 21, June 2001, as part of an
hour long active region observation; a total of 52 of the TRACE 171
Å and 68 TRACE 1600 Å images have been analyzed from that sequence,
as well as 35 images provided by the MDI aboard SOHO. In this poster,
we will discuss the analysis of the events and the implications of
our cooling model.

---------------------------------------------------------
Title: Active Region Transient Events Observed with TRACE
Authors: Seaton, Daniel B.; Winebarger, Amy R.; DeLuca, Edward E.;
Golub, Leon; Reeves, Katharine K.; Gallagher, Peter T.
2001ApJ...563L.173S Altcode:
Nearly all active region observations made by the Transition Region
and Coronal Explorer (TRACE) contain seemingly spontaneous, short-lived
brightenings in small-scale loops. In this paper, we present an analysis
of these brightenings using high-cadence TRACE observations of Active
Region 9506 on 2001 June 21 from 15:17:00 to 15:46:00 UT. During this
time frame, several brightenings were observed over a neutral line in
a region of emerging flux that had intensity signatures in both the
171 Å (logTe~6.0) and 1600 Å (logTe~4.0-5.0)
channels. The events had a cross-sectional diameter of approximately
2" and a length of 25". We interpret these as reconnection events
associated with flux emergence, possible EUV counterparts to active
region transient brightenings.

---------------------------------------------------------
Title: TRACE Observations of the 15 November 1999 Transit of Mercury
Authors: Schneider, G.; Pasachoff, J. M.; Golub, L.
2001DPS....33.1002S Altcode: 2001BAAS...33.1037S
We present time-resolved (38s) high-resolution (500mas) imagery of
the ingress phase of the 15 November 1999 transit of Mercury observed
with the Transition Region Coronal Explorer (TRACE) spacecraft in its
"white light" (1600 - 6000 Angstrom) channel. As part of our photometric
and astrometic analyses of this data set we examined the images in and
around the point of internal tangency for evidence of the historical
"black drop effect". After calibration (including careful removal of
image/instrumental artifacts and flat-fielding) the only radially
directed brightness anisotropes found were due to the interacting
effects the back-light solar limb-darkening, diffraction of photospheric
light around the Mercurian disk, and the instrument's Point Spread
Function. We discuss, and model, these effects as they would have
applied to earlier ground-based observations of Mercurian transits
(also including the effects of atmospheric "seeing") to explain the
historical basis for the black drop effect.

---------------------------------------------------------
Title: Nearest Star: The Surprising Science of Our Sun
Authors: Golub, Leon; Pasachoff, Jay M.; Lopez, Ramon E.
2001PhT....54k..59G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Magnetic Structure of a Coronal X-Ray Bright Point
Authors: Brown, D. S.; Parnell, C. E.; Deluca, E. E.; Golub, L.;
McMullen, R. A.
2001SoPh..201..305B Altcode:
X-ray bright points are small dynamic loop structures that are observed
all over the solar corona. The high spatial and temporal resolution of
the TRACE instrument allows bright points to be studied in much greater
detail than previously possible. This paper focuses on a specific
bright point which occurred for about 20 hours on 13-14 June 1998 and
examines its dynamic structure in detail. This example suggests that
the mechanisms that cause bright points to form and evolve are more
complex than previously thought. In this case, reconnection probably
plays a major part during the formation and brightening of the loop
structure. However, later on the foot points rotate injecting twist
into the bright point which may cause an instability to occur with
dynamic results.

---------------------------------------------------------
Title: Science Objectives of the Solar B X-Ray Telescope
Authors: DeLuca, E. E.; Golub, L.; Bookbinder, J.
2001AGUSM..SH31D04D Altcode:
The X-Ray Telescope (XRT) on the Solar B Mission will set a new
standard for high resolution full disk imaging of hot solar coronal
plasma. The optimized grazing incidence optic will have more than twice
the resolution of Yohkoh's SXT, a wider temperature response and much
less scatter. We will present the expected instrument performance,
describe the science objectives, and review sample observing plans
for the XRT.

---------------------------------------------------------
Title: Apparent Flows above an Active Region Observed with the
Transition Region and Coronal Explorer
Authors: Winebarger, Amy R.; DeLuca, Edward E.; Golub, Leon
2001ApJ...553L..81W Altcode:
The Transition Region and Coronal Explorer (TRACE) observed Active
Region 8395 on 1998 December 1 from 1:30:00 to 3:00:00 UT at high
cadence in the Fe IX/Fe X channel (logTe~6.0). Throughout
the observing time, brightness variations along a dense bundle of
coronal field lines in the southwest corner of the active region
were observed. Movies made of this region give the impression of
continuous intermittent outflow in this bundle of coronal loops; such
apparent outflow is often seen in the TRACE data. In this Letter,
we present an analysis of four separate flow events occurring in
three different loops. These events are used as tracers of the flow
in order to characterize its physical properties, such as apparent
velocity. The projected velocities of the intensity fronts of these
flows (and hence lower limits of true velocities) are between 5 and
20 km s-1. Comparisons of the observed intensities with
those predicted by a quasi-static model suggest that the events can be
explained only by a mass flow from the chromosphere into the corona. The
persistence of the flows, and their ubiquity in the TRACE observations,
indicates that hydrostatic loops models are not applicable to this
class of coronal structures.

---------------------------------------------------------
Title: Recent Results from TRACE (CD-ROM Directory: contribs/golub)
Authors: Golub, L.
2001ASPC..223..325G Altcode: 2001csss...11..325G
No abstract at ADS

---------------------------------------------------------
Title: Nearest star : the surprising science of our sun
Authors: Golub, Leon; Pasachoff, Jay M.
2001nsss.book.....G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: High-resolution grazing incidence telescope for the Solar-B
observatory
Authors: Golub, Leon; DeLuca, Edward E.; Bookbinder, Jay A.; Cheimets,
Peter; Shibasaki, Kiyoto; Sakao, Taro; Kano, Ryouhei
2000SPIE.4139..313G Altcode:
The X-ray observations from the Yohkoh SXT provided the greatest
step forward in our understanding of the solar corona in nearly two
decades. We believe that the scientific objectives of the Solar-B
mission can best be achieved with an X-ray telescope (XRT) similar to
the SXT, but with significant improvements in spatial resolution and
in temperature response that take into account the knowledge gained
from Yohkoh. We present the scientific justification for this view,
discuss the instrumental requirements that flow from the scientific
objectives, and describe the instrumentation that will meet these
requirements. XRT is a grazing-incidence (GI) modified Wolter I X-ray
telescope, of 35 cm inner diameter and 2.7 m focal length. The 2048 X
2048 back-illuminated CCD has 13.5 (mu) pixels, corresponding to 1.0
arcsec and giving full Sun field of view. This will be the highest
resolution GI X-ray telescope ever flown for Solar coronal studies,
and it has been designed specifically to observe both the high and
low temperature coronal plasma.

---------------------------------------------------------
Title: Solar Spectroscopy and Diagnostics: X-ray Emission
Authors: Golub, L.
2000eaa..bookE2234G Altcode:
X-ray emission from the Sun arises primarily from the solar outer
atmosphere, particularly the hot corona. During transient events, such
as flares and coronal mass ejections, there is also enhanced emission
of both soft and hard x-rays from plasma above ten million kelvins
(see SOLAR FLARES: RELATION TO CORONAL MASS EJECTIONS). Outside of
flares, the bulk of the coronal plasma is at temperatures ...

---------------------------------------------------------
Title: Determination of Flare Heating and Cooling Using the Transition
Region and Coronal Explorer
Authors: Antiochos, S. K.; DeLuca, E. E.; Golub, L.; McMullen, R. A.
2000ApJ...542L.151A Altcode:
We describe how the Transition Region and Coronal Explorer 171 Å
observations can be used to determine the properties of flare-loop
heating. The key point is that the evolution of a loop transition region
(TR) is much easier to measure quantitatively than the bulk flare plasma
because the TR emission originates from an unobscured source with simple
geometry. We derive general analytic expressions for the evolution
of a flare-loop TR that, in principle, permit a determination of the
heating function from the observations. These results are compared with
observations of the 1998 September 20 flare. We find that the observed
evolution of the flare ribbons is in good agreement with our model for
the evaporative cooling of flare loops and that the heating in these
loops is incompatible with the assumption of spatial uniformity.

---------------------------------------------------------
Title: The Topology and Evolution of the Bastille Day Flare
Authors: Aulanier, G.; DeLuca, E. E.; Antiochos, S. K.; McMullen,
R. A.; Golub, L.
2000ApJ...540.1126A Altcode:
On 1998 July 14, a class M3 flare occurred at 12:55 UT in AR 8270
near disk center. Kitt Peak line-of-sight magnetograms show that the
flare occurred in a δ spot. Mees vector magnetograms show a strong
shear localized near a portion of the closed neutral line around the
parasitic polarity of the δ spot. Observations of the flare in 171,
195, and 1600 Å have been obtained by TRACE, with ~=40 s temporal
and 0.5" spatial resolutions. They reveal that small-scale preflare
loops above the sheared region expanded and disappeared for more than
1 hr before flare maximum. During the flare, bright loops anchored in
bright ribbons form and grow. This occurs while large-scale dimmings,
associated with large expanding loops, develop on both sides of
the active region. This suggests that the flare was eruptive and
was accompanied by a coronal mass ejection (CME). Magnetic field
extrapolations reveal the presence of a null point in the corona, with
its associated “spine” field line, and its “fan” surface surrounding
the parasitic polarity. We show that while the whole event occurs,
the intersections of the “fan” and the “spine” with the photosphere
brighten and move continuously. The interpretation of the event shows
that the magnetic evolution of the eruptive flare is strongly coupled
with its surrounding complex topology. We discuss evidence supporting a
“magnetic breakout” process for triggering this eruptive flare. We
finally conclude that multipolar fields cannot be neglected in the
study and modeling of the origin of CMEs in the corona.

---------------------------------------------------------
Title: Emergence of sheared magnetic flux tubes in an active region
observed with the SVST and TRACE
Authors: Deng, Y. Y.; Schmieder, B.; Engvold, O.; DeLuca, E.; Golub, L.
2000SoPh..195..347D Altcode:
The active region NOAA AR 8331 was a target of an international
ground-based observational campaign in the Canaries and coordinated
with space instruments (TRACE and Yohkoh). We focus our study on
observations obtained with the SVST at LaPalma, and with TRACE. On 10
September 1998, arch-filament systems were observed with high spatial
and temporal resolution, from the lower to the upper atmosphere of
the Sun, during five hours. Flux tubes emerged with increasing shear,
which apparently led to energy release and heating in the overlying
corona. A model for filament formation by the emergence of U-shaped
loops from the subphotosphere, as proposed by Rust and Kumar (1994),
is supported by the present observations. The coronal response to these
events is visualized by rising, medium-scale loop brightenings. The
low-lying X-ray loops show short-lived, bright knots which are thought
to result from interaction between different loop systems.

---------------------------------------------------------
Title: A Brightening Coronal Loop Observed by TRACE. I. Morphology
and Evolution
Authors: Reale, F.; Peres, G.; Serio, S.; DeLuca, E. E.; Golub, L.
2000ApJ...535..412R Altcode:
We analyze the transient brightening of a solar coronal loop observed,
at high time cadence (30 s) and spatial resolution (0.5" pixel size),
with the Transition Region and Coronal Explorer (TRACE) in the 171 Å
band on 1998 June 26. The loop, located in AR 8253, is ~1010
cm long and inclined with respect to the vertical to the solar
surface. Its geometry and shape do not change significantly during the
brightening, which lasts for ~2 hr and is preceded by highly dynamic
events in nearby and perhaps interacting loops. The loop footpoints
brighten first; after ~10 minutes, moving brightness fronts rise
initially from the northern footpoint, and after another ~7 minutes
from the southern one, at an apparent speed ~100 km s-1, the
whole loop becoming clearly visible afterward. During the rising phase
the loop evolves coherently as a single magnetic tube. The brightness
profile is asymmetric with respect to the loop apex at all times; the
brightness contrast between the footpoints and the apex decreases with
time from a ratio of ~10 to ~3. After the loop has become all visible,
the several parallel filaments which form it follow an independent
evolution. Assuming a plasma temperature of ~1 MK, we infer a plasma
density of ~6×108 cm -3 and a pressure of ~0.2
dyn cm-2 close to the loop apex at the luminosity maximum. A
companion paper is devoted to modeling the rising phase of this event.

---------------------------------------------------------
Title: A Brightening Coronal Loop Observed by TRACE. II. Loop Modeling
and Constraints on Heating
Authors: Reale, F.; Peres, G.; Serio, S.; Betta, R. M.; DeLuca, E. E.;
Golub, L.
2000ApJ...535..423R Altcode:
This is the second of two papers dedicated to the brightening of a
coronal loop observed by the Transition Region and Coronal Explorer
(TRACE) on 1998 June 26; it aims at hydrodynamic modeling of the
brightening. Since the loop geometry is practically unchanged during
the brightening, the evolution of the plasma confined in the loop is
described with a one-dimensional hydrodynamic time-dependent numerical
model, and from the results the emission along the loop in the TRACE
171 Å band is synthesized. The information from Paper I is used
to derive the geometry and the initial configuration of the loop as
well as for comparison with the results of the model. The modeling is
focused to determine the amount, spatial distribution, and evolution
of the heating deposited in the loop to make the modeled evolution
close to that observed with TRACE. We find that, in order to match the
observed evolution and distribution of the brightness along the loop,
the heating has to be nonsymmetrical in the loop, in particular,
deposited between the apex and one footpoint (3×109 cm
from the southern footpoint). A reasonable match with observations
is obtained by assuming that the heating is switched on abruptly and
then kept constant for the whole rising phase. An even better match
is obtained with the heating high and constant for 100 s and then
decaying exponentially with an e-folding time of 300 s. We discuss
the resulting physical scenario; a bright irregular structure close
to the loop in the TRACE images may be a tracer of the heating release.

---------------------------------------------------------
Title: The X-ray telescope on Solar B.
Authors: Deluca, E. E.; Golub, L.; Bookbinder, J.; Cheimets, P.;
Shibasaki, K.; Sakao, T.; Kano, R.
2000BAAS...32..827D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The X-Ray Telescope on Solar B
Authors: DeLuca, E. E.; Golub, L.; Bookbinder, J.; Cheimets, P.;
Shibasaki, K.; Sakao, T.; Kano, R.
2000SPD....31Q0293D Altcode:
The X-ray observations from the Yohkoh SXT provided the greatest
step forward in our understanding of the solar corona in nearly two
decades. We believe that the scientific objectives of the Solar-B
mission can best be achieved with an X-ray telescope (XRT) similar to
the SXT, but with significant improvements in spatial resolution and in
temperature response that take into account the knowledge gained from
Yohkoh. We present the scientific justification for this view, discuss
the instrumental requirements that flow from the scientific objectives,
and describe the instrumentation to meet these requirements. XRT is
a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35cm
inner diameter and 2.7m focal length. The 2048x2048 back-illuminated
CCD has 13.5&amp;mu pixels, corresponding to 1.0 arcsec and giving
full Sun field of view. This will be the highest resolution GI X-ray
telescope ever flown for Solar coronal studies, and it has been designed
specifically to observe both the high and low temperature coronal
plasma. A small optical telescope provide visibles light images for
coalignment with the Solar-B optical and EUV instruments. The US XRT
team is support by a NASA Contract from MSFC.

---------------------------------------------------------
Title: The Topology and Evolution of the Bastille Day Flare Observed
by TRACE
Authors: Aulanier, G.; Antiochos, S. K.; DeLuca, E. E.; McMullen,
R. A.; Golub, L.
2000SPD....31.1402A Altcode: 2000BAAS...32..846A
On July 14, 1998, a class M3 flare occurred at 12:55 UT in AR 8270
near disc center. Kitt Peak line-of-sight magnetograms show that the
flare occurred in a δ -spot. Mees vector magnetograms show a strong
shear localized near a portion of the closed neutral line around the
parasitic polarity of the δ -spot. Observations of the flare in 171
Angstroms, 195 Angstroms and 1600 Angstroms have been obtained by TRACE,
with ~= 40 s temporal and 0.5 arcsec spatial resolutions. They reveal
that small-scale pre-flare loops above the sheared region expanded and
disappeared for more than one hour before flare maximum. During the
flare, bright loops anchored in bright ribbons form and grow. This
occurs while large-scale dimmings, associated with large expanding
loops, develop on both sides of the AR. This suggests that the
flare was eruptive, and was accompanied by a coronal mass ejection
(CME). Magnetic field extrapolations reveal the presence of a null
point in the corona, with its associated “spine” field line, and
its “fan” surface surrounding the parasitic polarity. We show that
while the whole event occurs, the intersections of the “fan” and the
“spine” with the photosphere brighten and move continuously. The
interpretation of the event shows that the magnetic evolution of
the eruptive flare is strongly coupled with its surrounding complex
topology. We discuss evidence supporting a “magnetic breakout”
process for triggering this eruptive flare. We finally conclude that
multipolar fields cannot be neglected in the study and modeling of
the origin of CMEs in the corona. This work is supported, at SAO by
a NASA contract to Lockheed-Martin, and at NRL by NASA and ONR.

---------------------------------------------------------
Title: TRACE and Yohkoh Observations of High-Temperature Plasma in
a Two-Ribbon Limb Flare
Authors: Warren, H. P.; Bookbinder, J. A.; Forbes, T. G.; Golub, L.;
Hudson, H. S.; Reeves, K.; Warshall, A.
1999ApJ...527L.121W Altcode:
The ability of the Transition Region and Coronal Explorer
(TRACE) to image solar plasma over a wide range of temperatures
(Te~104-107 K) at high spatial
resolution (0.5" pixels) makes it a unique instrument for observing
solar flares. We present TRACE and Yohkoh observations of an M2.4
two-ribbon flare that began on 1999 July 25 at about 13:08 UT. We
observe impulsive footpoint brightenings that are followed by the
formation of high-temperature plasma (Te&gt;~10 MK)
in the corona. After an interval of about 1300 s, cooler loops
(Te&lt;2 MK) form below the hot plasma. Thus, the
evolution of the event supports the qualitative aspects of the standard
reconnection model of solar flares. The TRACE and Yohkoh data show that
the bulk of the flare emission is at or below 10 MK. The TRACE data
are also consistent with the Yohkoh observations of hotter plasma
(Te~15-20 MK) existing at the top of the arcade. The
cooling time inferred from these observations is consistent with a
hybrid cooling time based on thermal conduction and radiative cooling.

---------------------------------------------------------
Title: Long-lived Coronal Loop Profiles from TRACE
Authors: Lenz, Dawn D.; DeLuca, Edward E.; Golub, Leon; Rosner, Robert;
Bookbinder, Jay A.; Litwin, Christof; Reale, Fabio; Peres, Giovanni
1999SoPh..190..131L Altcode:
An initial study of long-lived loops observed with TRACE (Lenz et al.,
1999) shows that they have no significant temperature stratification
and that they are denser than the classic loop model predicts. Models
that agree better with the observations include a loop consisting of a
bundle of filaments at different temperatures and a loop with momentum
input by MHD waves. Some implications for coronal heating models and
mechanisms are discussed.

---------------------------------------------------------
Title: An Eruptive Flare Observed by TRACE as a Test for the Magnetic
Authors: Aulaneir, G.; Deluca, E. E.; Golub, L.; Artzner, Guy; Sabine
Coquillart; Hochedez, Jean-Francois; Delaboudinier, Jean-Pierre
1999ESASP.446..131A Altcode: 1999soho....8..131A
No abstract at ADS

---------------------------------------------------------
Title: Solar-B X-ray Telescope (XRT) Concept Study Report
Authors: Golub, Leon
1999STIN...9913119G Altcode:
The X-ray observations from the Yohkoh SXT provided the greatest
step forward in our understanding of the solar corona in nearly two
decades. Expanding on the accomplishments of Yohkoh, we believe that
the scientific objectives of the Solar-B mission are achieved with a
significantly improved X-ray telescope (XRT) similar to the SXT. The
Solar-B XRT will have twice the spatial resolution and a broader
temperature response, while building on the knowledge gained from the
successful Yohkoh mission. We present the scientific justification
for this view, discuss the instrumental requirements that flow from
the scientific objectives, and describe the instrumentation to meet
these requirements. We then provide a detailed discussion of the
design activities carried out during Phase A, noting the conclusions
that were reached in terms of their implications for the detailed
design activities which are now commencing. Details of the instrument
that have changed as a result of the Phase A studied are specifically
noted, and areas of concern going into Phase B are highlighted. XRT
is a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35cm
inner diameter and 2.7m focal length. The 2048x2048 back-illuminated CCD
(now an ISAS responsibility) has 13.5 micron pixels, corresponding to
1.0 arcsec and giving full Sun field of view. This will be the highest
resolution GI X-ray telescope ever flown for Solar coronal studies,
and it has been designed specifically to observe both the high and
low temperature coronal plasma. A small optical telescope provides
visible light images for co-alignment with the Solar-B optical and
EUV instruments. The XRT science team is working in close cooperation
with our Japanese colleagues in the design and construction of this
instrument. All of the expertise and resources of the High Energy and
Solar/Stellar Divisions of the Center for Astrophysics are being made
available to this program, and our team will carry its full share of
responsibility for mission operations, data reduction and education and
public outreach. All aspects of the XRT design were reviewed during
Phase A. The study focussed particularly on those aspects that have
the greatest affect on instrument performance and extended lifetime,
on the image quality error budget, and on the camera (mechanical and
electrical) interface and the instrument mounting interfaces. The
present instrument design differs in some details from that originally
proposed. Selection of the XRT for Phase A study was contingent upon the
removal of the camera and its associated electronics, and the acceptance
of a stringent cost cap. The removal of the electronics left the XRT
without control electronics for the instrument mechanisms. A mechanism
controller was therefore added. The removal of the camera resulted
in major complications to the integration and test plan. After many
discussions, it was decided that the system would be less expensive,
and the risk of unacceptable performance lower, if we include a
focus mechanism. The remainder of the XRT design baseline matches the
proposed configuration. Data requirements for the XRT are driven by
the science plans, which are based on the physical processes in the
solar outer atmosphere. Discussions to date of the XRT observing plan,
both alone and in conjunction with the other Solar-B instruments,
shows that the XRT needs 2 Gbits of on-board storage, at least one
circulating buffer of 640 Mbits, and twelve 10- minute downlinks per
day in order to carry out its required programs.

---------------------------------------------------------
Title: An Eruptive Flare Observed by TRACE as a Test for the Magnetic
Authors: Aulaneir, G.; Deluca, E. E.; Golub, L.; McMullen, R. A.;
Karpen, J. T.; Antiochos, S. K.
1999ESASP.446..135A Altcode: 1999soho....8..135A
No abstract at ADS

---------------------------------------------------------
Title: Observed Magnetic Structure of X-Ray Bright Points from TRACE
and MDI
Authors: Brown, D. S.; Parnell, C.; Deluca, E.; McMullen, R.; Golub, L.
1999ASPC..184...81B Altcode:
From 13th-17th June 1998, TRACE and MDI simultaneously observed the
same quiet region of the Sun. From these observations the fascinating
and complex structure of x-ray bright points, intense small scale
brightenings that occur throughout the solar corona, can be seen in
great detail. For the first time, it has been possible to study bright
points for their entire lifetime with a cadence of 2 minutes and a
temporal resolution of 0.5 arcsecs. One particular bright point which
lasted two days exhibited dynamic structural behaviour which became
increasingly complex and lead to its sudden eruptive demise. With the
use of MDI magnetograms, it is possible to extrapolate the magnetic
structure using an analytical constant α force-free approximation. This
has been used to help us to explain the topology and behaviour of the
bright point. By comparing two of TRACE's Fe lines (FeIX and FeXII) the
spatial and temporal temperature and density structure of the bright
point has been investigated. This analysis indicates that this bright
point is made up of a complex system of dense loops. By understanding
the magnetic, temperature and density structure of the bright point,
it is hoped that the mechanism by which it is heated can be gained.

---------------------------------------------------------
Title: A new view of the solar outer atmosphere by the Transition
Region and Coronal Explorer
Authors: Schrijver, C. J.; Title, A. M.; Berger, T. E.; Fletcher, L.;
Hurlburt, N. E.; Nightingale, R. W.; Shine, R. A.; Tarbell, T. D.;
Wolfson, J.; Golub, L.; Bookbinder, J. A.; DeLuca, E. E.; McMullen,
R. A.; Warren, H. P.; Kankelborg, C. C.; Handy, B. N.; De Pontieu, B.
1999SoPh..187..261S Altcode:
The Transition Region and Coronal Explorer (TRACE) - described in the
companion paper by Handy et al. (1999) - provides an unprecedented
view of the solar outer atmosphere. In this overview, we discuss the
initial impressions gained from, and interpretations of, the first
million images taken with TRACE. We address, among other topics,
the fine structure of the corona, the larger-scale thermal trends,
the evolution of the corona over quiet and active regions, the high
incidence of chromospheric material dynamically embedded in the coronal
environment, the dynamics and structure of the conductively dominated
transition region between chromosphere and corona, loop oscillations
and flows, and sunspot coronal loops. With TRACE we observe a corona
that is extremely dynamic and full of flows and wave phenomena, in
which loops evolve rapidly in temperature, with associated changes in
density. This dynamic nature points to a high degree of spatio-temporal
variability even under conditions that traditionally have been referred
to as quiescent. This variability requires that coronal heating can
turn on and off on a time scale of minutes or less along field-line
bundles with cross sections at or below the instrumental resolution
of 700 km. Loops seen at 171 Å (∼1 MK) appear to meander through
the coronal volume, but it is unclear whether this is caused by the
evolution of the field or by the weaving of the heating through the
coronal volume, shifting around for periods of up to a few tens of
minutes and lighting up subsequent field lines. We discuss evidence
that the heating occurs predominantly within the first 10 to 20 Mm
from the loop footpoints. This causes the inner parts of active-region
coronae to have a higher average temperature than the outer domains.

---------------------------------------------------------
Title: The transition region and coronal explorer
Authors: Handy, B. N.; Acton, L. W.; Kankelborg, C. C.; Wolfson, C. J.;
Akin, D. J.; Bruner, M. E.; Caravalho, R.; Catura, R. C.; Chevalier,
R.; Duncan, D. W.; Edwards, C. G.; Feinstein, C. N.; Freeland, S. L.;
Friedlaender, F. M.; Hoffmann, C. H.; Hurlburt, N. E.; Jurcevich,
B. K.; Katz, N. L.; Kelly, G. A.; Lemen, J. R.; Levay, M.; Lindgren,
R. W.; Mathur, D. P.; Meyer, S. B.; Morrison, S. J.; Morrison, M. D.;
Nightingale, R. W.; Pope, T. P.; Rehse, R. A.; Schrijver, C. J.;
Shine, R. A.; Shing, L.; Strong, K. T.; Tarbell, T. D.; Title, A. M.;
Torgerson, D. D.; Golub, L.; Bookbinder, J. A.; Caldwell, D.; Cheimets,
P. N.; Davis, W. N.; Deluca, E. E.; McMullen, R. A.; Warren, H. P.;
Amato, D.; Fisher, R.; Maldonado, H.; Parkinson, C.
1999SoPh..187..229H Altcode:
The Transition Region and Coronal Explorer (TRACE) satellite, launched
2 April 1998, is a NASA Small Explorer (SMEX) that images the solar
photosphere, transition region and corona with unprecedented spatial
resolution and temporal continuity. To provide continuous coverage
of solar phenomena, TRACE is located in a sun-synchronous polar
orbit. The ∼700 Mbytes of data which are collected daily are made
available for unrestricted use within a few days of observation. The
instrument features a 30-cm Cassegrain telescope with a field of view
of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec
pixels). TRACE contains multilayer optics and a lumogen-coated CCD
detector to record three EUV wavelengths and several UV wavelengths. It
observes plasmas at selected temperatures from 6000 K to 10 MK with
a typical temporal resolution of less than 1 min.

---------------------------------------------------------
Title: Temperature and Emission-Measure Profiles along Long-lived
Solar Coronal Loops Observed with the Transition Region and Coronal
Explorer
Authors: Lenz, Dawn D.; DeLuca, Edward E.; Golub, Leon; Rosner,
Robert; Bookbinder, Jay A.
1999ApJ...517L.155L Altcode: 1999astro.ph..3491L
We report an initial study of temperature and emission-measure
distributions along four steady loops observed with the Transition
Region and Coronal Explorer at the limb of the Sun. The temperature
diagnostic is the filter ratio of the extreme-ultraviolet 171 and 195
Å passbands. The emission-measure diagnostic is the count rate in the
171 Å passband. We find essentially no temperature variation along
the loops. We compare the observed loop structure with theoretical
isothermal and nonisothermal static loop structure.

---------------------------------------------------------
Title: A new view of the solar corona from the transition region
and coronal explorer (TRACE)
Authors: Golub, L.; Bookbinder, J.; Deluca, E.; Karovska, M.; Warren,
H.; Schrijver, C. J.; Shine, R.; Tarbell, T.; Title, A.; Wolfson,
J.; Handy, B.; Kankelborg, C.
1999PhPl....6.2205G Altcode:
The TRACE Observatory is the first solar-observing satellite in the
National Aeronautics and Space Administration's (NASA) Small Explorer
series. Launched April 2, 1998, it is providing views of the solar
transition region and low corona with unprecedented spatial and
temporal resolution. The corona is now seen to be highly filamented,
and filled with flows and other dynamic processes. Structure is seen
down to the resolution limit of the instrument, while variability and
motions are observed at all spatial locations in the solar atmosphere,
and on very short time scales. Flares and shock waves are observed,
and the formation of long-lived coronal structures, with consequent
implications for coronal heating models, has been seen. This overview
describes the instrument and presents some preliminary results from
the first six months of operation.

---------------------------------------------------------
Title: The Advanced Solar Coronal Explorer Mission (ASCE)
Authors: Kohl, J.; Cranmer, S.; Gardner, L.; Golub, L.; Raymond, J.;
Smith, P. L.; Strachan, L.; Howard, R.; Moses, D.; Socker, D.; Wang,
D.; Fisher, R. R.; Davila, J.; St. Cyr, C.; Noci, G.; Tondello, G.
1999AAS...194.6506K Altcode: 1999BAAS...31Q.928K
The Advanced Solar Coronal Explorer (ASCE) mission was selected
for a Phase A Concept Study in the current round of proposed MIDEX
missions. It addresses three fundamental problems: 1) What physical
processes heat coronal holes and drive the fast solar wind? 2) What
physical processes heat streamers and drive the slow solar wind? and 3)
How are coronal mass ejections (CMEs) heated and accelerated, and what
role to they play in the evolution of the solar magnetic field. ASCE
has two instruments, the Spectroscopic and Polarimetric Coronagraph
(SPC) and the Extreme Ultraviolet Imager (EUVI). A deployable boom
supports a distant external occulter that allows large aperture optics
for the SPC coronagraphic channels. SPC's EUV channels will provide
spectroscopy of the extended solar corona with 30 - 200 times the
sensitivity of UVCS/SOHO and the first He II 30.4 nm spectroscopy of
the extended corona. SPC's Large Aperture Spectroscopic Coronagraph
channel will provide two orders of magnitude improvement in stray
light suppression for wide field visible spectroscopy and 2 arcsec
resolution elements for imaging and polarimetry. EUVI provides full
disk imaging with 0.9 arcsec resolution elements and extremely high
cadence. ASCE is designed to determine the thermal, kinetic, and
wave energy densities in coronal structures, determine the rates of
transformation among these forms of energy, their flow in space, and
their loss to radiation, and determine the composition and ionization
state of the corona in static and transient conditions.

---------------------------------------------------------
Title: Future EUV/Soft X-ray Observations
Authors: Golub, L.
1999AAS...194.6504G Altcode: 1999BAAS...31..927G
The SEC Roadmap identifies Quests and Science Themes which form
the organizational structure for the present and planned missions
within the Office of Space Science at NASA. In order to carry out
the scientific program defined by the Roadmap, a crucial component
involves understanding of the causes of solar phenomena, such as the
solar wind, the high-temperature corona, solar flares and coronal
mass ejections. Furthering our understanding often involves direct
observation of the million-degree coronal plasma, which is best seen
at X-ray wavelengths. We will review the present status of such
observations, and discuss what appear at this time to be the most
promising directions for future observations. These include currently
planned missions, such as HESSI, Solar-B and STEREO, as well as the
exciting new possibilities opened up by recent advances in theory and
in instrumental techniques.

---------------------------------------------------------
Title: The Solar Corona
Authors: Golub, Leon; Pasachoff, Jay M.; Smartt, Raymond N.
1999AmJPh..67..263G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Analysis and comparison of loop structures imaged with NIXT
and Yohkoh/SXT
Authors: Di Matteo, V.; Reale, F.; Peres, G.; Golub, L.
1999A&A...342..563D Altcode:
We analyze and compare five coronal regions simultaneously observed
by NIXT and Yohkoh/SXT on April 12, 1993. The compact loop structures
(length ~ 10(9) cm) imaged in three regions with NIXT and with SXT
have a good general morphological correspondence. A large scale (~
1.7 x 10(10) cm) and an intermediate scale (~ 5 x 10(9) cm) structure
observed in the NIXT image have no obvious counterpart in the SXT
image. The pressure of the loop plasma detected by NIXT is derived
from the brightness profile along the loops by applying a method based
on loop models. The pressure of the loop plasma in the SXT band has
also been derived from loop models on the basis of the temperature
obtained from the standard Yohkoh data analysis. NIXT pressures are
systematically lower than those found with SXT. By comparing the
measured total loop luminosity to that expected on the basis of loop
models, we constrain quantitatively the volume filling factor of the
plasma emitting respectively in the NIXT and SXT bands. The filling
factors obtained in the NIXT band for the compact and intermediate
loops are very low (10(-3) - 10(-2) ), but they are of the order of
unity for the large structure. The low filling factors suggest a strong
loop filamentation. The filling factors for the compact structures are
instead of the order of unity in the SXT band. We discuss our results
and propose a scenario for their interpretation.

---------------------------------------------------------
Title: On the Ability of an Extreme-Ultraviolet Multilayer
Normal-Incidence Telescope to Provide Temperature Information for
Solar Plasmas
Authors: Feldman, U.; Laming, J. M.; Doschek, G. A.; Warren, H. P.;
Golub, L.
1999ApJ...511L..61F Altcode:
In recent years, multilayer-coated optics have been used in solar-soft
X-ray and extreme-ultraviolet telescopes to record high-resolution,
full Sun images. The multilayer coatings reflect efficiently over rather
narrow wavelength bands that are selected to contain spectral emission
lines considered to have plasma diagnostic importance for determining
approximate electron temperatures. The purpose of this Letter is to
discuss the effect of continuum emission on the response of multilayer
passbands and the effect of this response on temperature determinations
in the 4×106-2×107 K range. Significant effects
are largely confined to continuum emission from flare plasma. The
flare free-free continuum in the EUV range is nearly temperature and
wavelength insensitive and dominates the emission in passbands that
are centered on quiet- to active-Sun coronal lines emitted by ions
such as Fe IX-Fe XV.

---------------------------------------------------------
Title: Observations of High-Temperature Flare Plasma with Transition
Region and Coronal Explorer (TRACE)
Authors: Reeves, K. K.; Golub, L.; Warren, H. P.
1999agu..meet..234R Altcode:
The so-called standard model of solar flares makes specific
predictions concerning the amount, location, and timing of both hot
(Te&gt;10 MK) and cool (Te&lt;2 MK) plasma in
solar flares. The ability of the Transition Region and Coronal Explorer
(TRACE) to image solar plasma over a wide range of temperatures
(Te~104-107 K) at high spatial
resolution (0.5″ pixels) make it a unique instrument for observing
solar flares and testing the model predictions. We present TRACE and
Yohkoh observations of an M2.4 two-ribbon flare that began on 1999
July 25 at about 13:08 UT. These observations are in qualitative
agreement with the essential elements of the reconnection model. We
observe impulsive footpoint brightenings that are quickly followed
by the formation of high-temperature plasma in the corona. After an
interval of about 1300 s cooler loops form below the hot plasma. The
cooling time inferred from the observations suggests large densities
(ne~1011 cm-3) for the high temperature
plasma so that radiative losses dominate the cooling process. The
TRACE data are consistent with the Yohkoh observations of a “hot”
(Te~15-20 MK) plasma existing at the top of the arcade.

---------------------------------------------------------
Title: The TRACE Mission: Initial Scientific Results
Authors: Title, A. M.; Tarbell, T. D.; Wolfson, J.; Schrijver, K.;
Fisher, R. R.; Gang, Th.; Golub, L.; McMullen, R. A.; Kankelborg,
C.; TRACE Collaboration
1998AAS...19310008T Altcode: 1998BAAS...30R1398T
TRACE (Transition Region and Coronal Explorer) is a Small Explorer
Mission (SMEX) devoted to studying the evolution and propagation
of fine-scale magnetic fields and plasma structures throughout the
solar atmosphere. The instrument consists of a telescope with a 30 cm
primary mirror, normal incidence coatings for three EUV bands (171,
195 and 284 Angstroms), and interference filters for UV bands (1216
to 1700 Angstroms) as well as white light (allowing the selection of
temperature ranges from ~ 6 000 to ~ 2 500 000 degrees K). The 1024
x 1024 CCD camera has a field of view of 8.5 arcmin with a spatial
resolution of 1 arcsec and exposure times of 0.002 to 260 sec with
a cadence as short as two seconds. The spacecraft was launched on
April 1, 1998, and first light for the telescope occurred on April
20. Observations have been collected nearly 24 hours per day since
then, with no significant problems in any segment of the spacecraft,
instrument, or mission operations. TRACE transmits about 3--4 GB of
data per week which gets automatically reformatted and becomes available
for the scientific community within approx. 24 hours. It is accessible
without restrictions (only guidelines) together with other informations
(technical details, educational material, movies, images,...) at:
http://vestige.lmsal.com/TRACE. The images reveal activity in the
solar atmosphere in stunning detail and include the first detailed
observations of a magnetic energy release. This magnetic reconnection
was observed on May 8, 1998, in a region of the solar atmosphere where
two sets of perpendicular magnetic loops expanded into each other (see
NASA Press Release 98-92). The TRACE mission has been developed and
operated by NASA's Goddard Space Flight Center, Lockheed Martin Solar
&amp; Astrophysics Laboratory, Smithsonian Astrophysical Observatory,
and Montana State University.

---------------------------------------------------------
Title: Book Review: The solar corona / Cambridge U Press, 1997
Authors: Golub, L.; Pasachoff, J. M.
1998SoPh..183..227G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: HIREX: results of the mission concept study
Authors: Bookbinder, Jay A.; Cheimets, Peter; Davis, William R.;
Caldwell, David; Golub, Leon; Deluca, Edward
1998SPIE.3442...22B Altcode:
HIREX is a suite of three complementary solar-pointed instruments
that is being proposed to NASA under the NASA MIDEX announcement
of opportunity. The main instrument is a 0.6m clear aperture, 240m
effective focal length normal incidence XUV telescope operated at 171
angstrom, with a spatial resolution of 0.01 inch. This main telescope
is complemented by two other instruments: 1) a 0.3 m context telescope
that images in a wavelength range that covers the UV and XUV spectral
regime, based on the TRACE design. This context telescope places the
high magnification, limited field of view images created by the high
resolution telescope in both spatial and temperature context. 2)
A spectrometer covering the spectral range from 170-220 angstrom,
based on the SERTS design.

---------------------------------------------------------
Title: A New View of the Solar Corona from TRACE.
Authors: Golub, Leon
1998APS..DPPH4I204G Altcode:
The TRACE Observatory is a small solar satellite in NASA's Small
Explorer series. Launched April 2, 1998, it is providing views of the
solar transition region and low corona with unprecedented spatial and
temporal resolution. The corona is now seen to be highly filamented,
and filled with flows and with dynamic processes. Structure is seen
down to the resolution limit of the instruments, while variability and
motions are observed at all spatial locations in the solar atmosphere,
and on very short timescales. Falres and shock waves are observed,
and the formation of long-lived coronal structures, with consequent
implications for coronal heating models, has been seen. In this
overview, we will describe the satellite and show some preliminary
results from the first six months of operation.

---------------------------------------------------------
Title: Super-X: a soft x-ray telescope for Solar-B
Authors: Acton, Loren W.; Bookbinder, Jay A.; Bruner, Marilyn E.;
Golub, Leon; Lemen, James R.
1998SPIE.3442..140A Altcode:
This paper describes the conceptual design of a soft x-ray
telescope, super-x, which we will propose for the Japan/US/UK Solar-B
mission. Super-X will break new ground in both angular resolution
and solar coronal temperature discrimination. The telescope design
is based upon the successful transition region and coronal explorer
instrument. It features four XUV spectral channels spanning the 0.3 to
20 MK temperature range with an angular resolution of approximately 0.27
seconds of arc. We will describe considerations affecting spectral line
selection and some details of the characteristics of the instrument.

---------------------------------------------------------
Title: Novel mirror mount design: TRACE primary mirror
Authors: Cheimets, Peter; Bookbinder, Jay A.; Davis, William R.;
Golub, Leon
1998SPIE.3445...28C Altcode:
Orbiting x-ray and XUV observatories are pushing the achievable
image resolution and with it, the requirements on mounted mirror
performance. The transitional region and coronal explorer (TRACE)
observatory uses a center mounted primary mirror that must maintain
its orientation in roll as well as pitch and way. A conformable bedding
was used to support the mirror against the expected launch loads in a
re-assembled mount, without inducing unacceptable mirror distortion. The
novel mirror mount design is discussed, and its resulting performance
described. This paper outlines the TRACE primary mirror assembly
design. The evolution of the design from the Space Weather and
Terrestrial Hazards assembly to the TRACE baseline design is presented.

---------------------------------------------------------
Title: Large-area thin aluminum filter design, handling, and testing
Authors: Cheimets, Peter; Bookbinder, Jay A.; Deluca, Edward; Caldwell,
David; Davis, William R.; Golub, Leon
1998SPIE.3445...96C Altcode:
The process of observing the Sun in the x-ray and extreme UV (XUV),
as we are now doing with the TRACE telescope, requires blocking
the tremendous amount of visible and RI light that dominates the
flux from the sun. If it is not blocked, the energy will swamp the
desired spectrum and cause thermal problems inside the telescope. The
most effective approach removing the energy is by filtering the
incoming light. One of the best materials for eliminating the
undesirable wavelengths is aluminum, which is semi- transparent
to x-ray and XUV, but blocks most light with wavelength redward of
850 angstrom. Unfortunately the aluminum must be extremely must be
extremely thin, &lt; 1600 angstrom thick, to provide the necessary
XUV transparency. To overcome the structural problem of supporting
large areas of extremely thin aluminum, the aluminum film is bonded
on a nickel mesh.

---------------------------------------------------------
Title: Structure and Dynamics of Coronal Plasma
Authors: Golub, Leon
1998STIN...9917617G Altcode:
Brief summaries of the four published papers produced within the present
performance period of NASA Grant NAGW-4081 are presented. The full
text of the papers are appended to the report. The first paper titled
"Coronal Structures Observed in X-rays and H-alpa Structures" was
published in the Kofu Symposium proceedings. The study analyzes cool
and hot behavior of two x-ray events, a small flare and a surge. It
was found that a large H-alpha surge appears in x-rays as a very weak
event, while a weak H-alpha feature corresponds to the brightest x-ray
emission on the disk at the time of the observation. Calculations of the
heating necessary to produce these signatures, and implications for the
driving and heating mechanisms of flares vs. surges are presented. The
second paper "Differential Magnetic Field Shear in an Active Region"
has been published in The Astrophysical Journal. The study compared the
three dimensional extrapolation of magnetic fields with the observed
coronal structure in an active region. Based on the fit between
observed coronal structure throughout the volume of the region and
the calculated magnetic field configurations, the authors propose a
differential magnetic field shear model for this active region. The
decreasing field shear in the outer portions of the AR may indicate
a continual relaxation of the magnetic field with time, corresponding
to a net transport of helicity outward. The third paper "Difficulties
in Observing Coronal Structure" has been published in the journal
Solar Physics. This paper discusses the evidence that the temperature
and density structure of the corona are far more complicated than had
previously been thought. The discussion is based on five studies carried
out by the group on coronal plasma properties, showing that any one
x-ray instrument does see all of the plasma present in the corona, that
hot and cool material may appear to be co-spatial at a given location
in the corona, and that simple magnetic field extrapolations provide
only a poor fit to the observed structure. The fourth paper "Analysis
and Comparison of Loop Structures Imaged with NIXT and Yohkoh/SXT" has
been published in Astronomy and Astrophysics. This paper analyzes and
compares a variety of coronal loops, deriving loop pressure and emission
measure from loop models. They are able to determine the volume filling
factor in the corona, which is found to be in the range 0.001 to 0.01
for compact loops, and of order 1 for large structures. The small values
suggest highly filamented structures, especially at lower temperatures.

---------------------------------------------------------
Title: First Results from the TRACE Mission
Authors: Title, A.; Tarbell, T.; Schrijver, C.; Wolfson, J.; Shine,
R.; Hurlburt, N.; Golub, L.; Deluca, E.; Bookbinder, J.; Handy, B.;
Acton, L.; Harrison, R.; Delaboudinere, J. -P.
1998AAS...192.1507T Altcode: 1998BAAS...30..841T
The TRACE spacecraft was launched on 1 April and all systems are
functioning as designed. The initial outgassing period will conclude
on 20 April and the science program will then begin. TRACE is a UV-EUV
imager with one arc second spatial resolution and is capable of taking
images with a cadence as high as two seconds. We will present images
and image sequences. We hope to present initial comparisons of magnetic
evolution and transition region and coronal brightenings.

---------------------------------------------------------
Title: Dynamic Responses to Magnetic Reconnection in Solar Arcades
Authors: Karpen, Judith T.; Antiochos, Spiro K.; Richard DeVore, C.;
Golub, Leon
1998ApJ...495..491K Altcode:
We present a numerical simulation of the interaction between two line
dipoles through magnetic reconnection in the lower solar atmosphere,
a process believed to be the origin of many manifestations of solar
activity. This work differs from previous studies in that the field
is sheared asymmetrically and that the dipoles have markedly unequal
field strengths. This calculation already yielded one key discovery,
denoted reconnection driven current filamentation, as described in a
previous Astrophysical Journal letter. In this paper we focus on the
chromospheric and coronal dynamics resulting from the shear-driven
reconnection of unequal dipoles, discuss the important implications for
chromospheric eruptions, compare our calculation with high-resolution
Normal Incidence X-Ray Telescope observations of a surge, and contrast
our results with the predictions of “fast reconnection” models.

---------------------------------------------------------
Title: The Global Coronal Structure Investigation
Authors: Golub, Leon
1998sao..reptS....G Altcode:
During the past year we have completed the changeover from the NIXT
program to the new TXI sounding rocket program. The NIXT effort, aimed
at evaluating the viability of the remaining portions of the NIXT
hardware and design, has been finished and the portions of the NIXT
which are viable and flightworthy, such as filters, mirror mounting
hardware, electronics and telemetry interface systems, are now part
of the new rocket payload. The backup NIXT multilayer-coated x-ray
telescope and its mounting hardware have been completely fabricated
and are being stored for possible future use in the TXI rocket. The
H-alpha camera design is being utilized in the TXI program for
real-time pointing verification and control via telemetry. A new
H-alpha camera has been built, with a high-resolution RS170 CCD camera
output. Two papers, summarizing scientific results from the NIXT
rocket program, have been written and published this year: 1. "The
Solar X-ray Corona," by L. Golub, Astrophysics and Space Science, 237,
33 (1996). 2. "Difficulties in Observing Coronal Structure," Keynote
Paper, Proceedings STEPWG1 Workshop on Measurements and Analyses of
the Solar 3D Magnetic Field, Solar Physics, 174, 99 (1997).

---------------------------------------------------------
Title: A Multiwavelength Study of Coronal Structure: A Simultaneous
Observation from NIXT and YOHKOH
Authors: Golub, Leon
1998sao..reptR....G Altcode:
Solar soft X-ray images taken simultaneously by the Yohkoh and the
Normal Incidence X-ray Telescope (NIXT) reveal significantly different
coronal structures. Coronal loops are more clearly seen in the Yohkoh
images, and the isolated island-like structures seen in the NIXT
image have been found to correspond to the footpoints of the Yohkoh
loops. The difference is due to the difference in the temperature
response of the telescopes: NIXT is sensitive to temperatures ranging
from 0.9 to 3 MK, while Yohkoh is more sensitive to temperatures above
2.5 MK. The morphological differences reflect the multi-temperature
(1-5 MK) nature of the solar coronal plasmas.

---------------------------------------------------------
Title: The HIREX Mission
Authors: Golub, L.
1998ESASP.417..157G Altcode: 1998cesh.conf..157G
No abstract at ADS

---------------------------------------------------------
Title: The Solar Corona
Authors: Golub, Leon; Pasachoff, Jay M.
1997soco.book.....G Altcode:
Observations from the ground and space have advanced our knowledge
of the solar corona dramatically over the past three decades. This
timely volume presents a lucid and synthesized review of the latest
observations of the solar corona and discusses how these observations
have advanced and shaped our understanding of coronal physics. In
the process, the authors introduce a wide variety of exciting
physics, including dynamo theory and radiative transfer. They also
demonstrate how the transient effects of the solar cycle effect "space
weather." This book provides a much-needed introduction to coronal
physics for advanced students and researchers.

---------------------------------------------------------
Title: Difficulties in Observing Coronal Structure
Authors: Golub, L.
1997SoPh..174...99G Altcode:
There has developed in recent years a substantial body of evidence to
indicate that the temperature and density structure of the corona are
far more complicated than had previously been thought. We review some
of the evidence and discuss some specific examples: observations of a
limb flare, showing that the cool Hα material is cospatial with the hot
X-ray emitting material; simultaneous NIXT and Yohkoh SXT observations
of an active region, showing that loops seen in one instrument are
not seen in the other, and that the effect works in both directions;
comparisons of extrapolated magnetic field measurements to the observed
coronal structure, indicating that neither potential nor constant-α
force-free fits are adequate. We conclude with a description of two
new instruments, the TRACE and the TXI, which will help to resolve
some of these difficulties.

---------------------------------------------------------
Title: The Solar-B Mission
Authors: Antiochos, Spiro; Acton, Loren; Canfield, Richard; Davila,
Joseph; Davis, John; Dere, Kenneth; Doschek, George; Golub, Leon;
Harvey, John; Hathaway, David; Hudson, Hugh; Moore, Ronald; Lites,
Bruce; Rust, David; Strong, Keith; Title, Alan
1997STIN...9721329A Altcode:
Solar-B, the next ISAS mission (with major NASA participation), is
designed to address the fundamental question of how magnetic fields
interact with plasma to produce solar variability. The mission has
a number of unique capabilities that will enable it to answer the
outstanding questions of solar magnetism. First, by escaping atmospheric
seeing, it will deliver continuous observations of the solar surface
with unprecedented spatial resolution. Second, Solar-B will deliver the
first accurate measurements of all three components of the photospheric
magnetic field. Solar-B will measure both the magnetic energy driving
the photosphere and simultaneously its effects in the corona. Solar-B
offers unique programmatic opportunities to NASA. It will continue an
effective collaboration with our most reliable international partner. It
will deliver images and data that will have strong public outreach
potential. Finally, the science of Solar-B is clearly related to the
themes of origins and plasma astrophysics, and contributes directly
to the national space weather and global change programs.

---------------------------------------------------------
Title: Detecting Siphon Flows in Coronal Loops
Authors: McMullen, Rebecca A.; Deluca, Edward E.; Golub, Leon
1997SPD....28.0148M Altcode: 1997BAAS...29..888M
While siphon flows are thought to be common in coronal loops,
detection in coronal emission has remained elusive. The Tuneable
X-Ray Imager (TXI) sounding rocket will produce images of the corona
in 4 Angstroms \ passbands around prominent emission lines between
170-200 Angstroms. This new instrument can also produce velocity
maps from difference images taken on either side of an emission
line. We present a study of the response of the TXI to siphon flows
in coronal loop models. The models show that loops with flows are
significantly fainter than the equivalent static loops. In addition,
contamination from nearby lines tends to mask the Doppler shift, even
with an instrument of excellent imaging capacity. We will outline more
detailed analysis methods that may reveal the siphon flows more clearly.

---------------------------------------------------------
Title: Difficulties in Observing Coronal Structure
Authors: Golub, Leon
1997nixt.reptR....G Altcode:
There has developed in recent years a substantial body of evidence to
indicate that the temperature and density structure of the corona are
far more complicated than had previously been thought. We review some
of the evidence and discuss some specific examples: observations of
a limb flare, showing that the cool H alphas material is cospatial
with the hot x-ray emitting material; simultaneous NIXT and Yohkoh
SXT observations of an active region, showing that loops seen in one
instrument are not seen in the other and that the effect works in both
directions; comparisons of extrapolated magnetic field measurements
to the observed coronal structure, indicating that neither potential
nor constant-alpha force-free fits are adequate. We conclude with a
description of two new instruments, the TRACE and the TXI, which will
help to resolve some of these difficulties.

---------------------------------------------------------
Title: Study of a Solar X-Ray Telescope
Authors: Golub, Leon
1997sao..rept.....G Altcode:
The highly structured nature of the outer solar atmosphere seems
to be intimately linked to the presence, at the solar surface, of
magnetic fields that have been generated inside the Sun and have
emerged to the surface. The corona is brightest (and also hottest)
at just those locations where the magnetic field has emerged from
inside the Sun. Dynamo theory predicts that strong magnetic fields
will be generated deep in the solar interior and that bundles or
'ropes' of magnetic flux will float to the surface. When this happens,
a magnetically bipolar region will become visible, extending above the
surface in a three-dimensional structure. The field lines penetrate
through the surface, showing two magnetic poles, and also exhibit
a three-dimensional structure above the surface. The structure
created by the field emergence is rooted in the (relatively) cool
photosphere and extends through the chromosphere and transition
region to the corona. Thus, the magnetic field creates a region,
called an active region, which contains portions at temperatures
from less than 104 K to greater than 106 K,
and is therefore visible at wavelengths from the infrared through
x-rays. The locations where the magnetic field leaves and reenters the
visible surface are called the 'footpoints' of the coronal structures
associated with the magnetic field. The magnetic fields themselves are
not directly visible. However, the hot coronal plasma is, for the most
part, constrained to follow the direction of the magnetic field lines
in the atmosphere. Now, 100 years after the discovery of x-rays by
Wilhelm Roentgen in 1896, we can routinely make observations of the
solar corona from outside the Earth's atmosphere in this region of
the electromagnetic spectrum. As shown by comparing x-ray images with
magnetograms, the bright corona over these bipolar magnetic regions
consists of closed structures that seem to follow the orientation of
the magnetic field. Although we can see down to the photosphere at
x-ray wavelengths when observing the disk of the Sun, this part of the
solar atmosphere emits so little that far from the peak of its Planck
curve it appears dark in x-ray images. This impression of hot plasma
following the magnetic field direction is further strengthened by
quantitative studies that calculate coronal magnetic field strength
and direction based on photospheric measurements and compare them
with the observed brightness and location of the x-ray emitting
structures. Such comparisons make it clear that, for the most part,
the hot plasma conforms to the geometry of the magnetic field and
that the coronal brightness is strongly linked to the strength of
the magnetic fields which have erupted to the solar surface from the
interior. It is also the case that the larger-scale, fainter corona,
as well as coronal holes, are strongly influenced by the large-scale
solar magnetic field. We may get a small hint of the reason that the
coronal plasma outlines the direction of B by examining the thermal
conductivity of a hot plasma in the presence of a magnetic field. This
quantity has enormously different values in the directions parallel and
perpendicular to the field for a coronal temperature of 106
K, a particle density of 109/cu cm and a magnetic field
strength of 100 G, the conductivity along the field is approximately 13
orders of magnitude greater than that perpendicular to the field. It
is therefore not surprising that a parcel of plasma which is locally
heated would conduct that heat preferentially in the direction of
the field. We also note that the thermal conductivity parallel to the
magnetic field increases with temperature T, while the perpendicular
conductivity decreases. To the extent that the loop aspect ratio,
i.e., the ratio of loop length to loop width, is determined by the
thermal conductivity, we would expect that higher temperature loops are
longer and thinner than cooler ones. However, if the loop width becomes
smaller than the spatial resolution of the observing instrument, this
effect will not be directly observable. For organizational purposes,
we provide a listing of some scientific objectives for a Solar-B x-ray
telescope, arranged in terms of identifiable features in the corona.

---------------------------------------------------------
Title: The TRACE Mission
Authors: Wolfson, J.; Bruner, M.; Jurcevich, B.; Lemen, J.; Schrijver,
K.; Shine, R.; Strong, K.; Tarbell, T.; Title, A.; Golub, L.;
Bookbinder, J.; Deluca, E.; Acton, L.; Handy, B.; Kankelborg, C.;
Fisher, R.
1997SPD....28.0143W Altcode: 1997BAAS...29..887W
The TRACE (Transition Region and Coronal Explorer) mission will explore
the connections between fine-scale magnetic fields and plasma structures
in the coronal, transition zone and temperature minimum regions of the
sun. TRACE will collect images of solar plasmas at temperatures from
10(4) to 10(7) K, with one arc second spatial resolution and excellent
temporal resolution and continuity. With a scheduled launch date of 15
December 1997, the mission will emphasize collaborative observations
with SoHO, enabling simultaneous observations of high-resolution images,
spectra, and magnetograms. The 30 cm aperture TRACE telescope uses four
normal-incidence coatings for the EUV and UV on quadrants of the primary
and secondary mirrors. Interference filters further isolate 5 different
UV bands. The images are co-aligned and internally stabilized against
spacecraft jitter. A 1024 x 1024 lumigen-coated CCD detector collects
images over an 8.5 x 8.5 arc minute field-of-view. LMATC, SAO, and GSFC
built the TRACE instrument, which was integrated with the GSFC-produced
SMEX spacecraft on 28 February (just over two years from the start
of its development). It will be put into a Sun-synchronous orbit and
operated in coordination with the SoHO Experiment Operations Facility at
GSFC. We are committed to maintaining a publicly accessible data base
for TRACE data. Browsing and data set requesting capabilities will be
provided at Web site www.space.lockheed.com/TRACE/TRACElinks.html. This
site already contains a large volume of information on the mission
including preliminary scientific observing programs and directions
as to how to participate in the mission now and in the future. This
project is supported by NASA contract NAS5-38099.

---------------------------------------------------------
Title: Structure and Dynamics of Coronal Plasmas
Authors: Golub, Leon
1997stcp.conf.....G Altcode:
During the past year this grant has funded research in the interaction
between magnetic fields and the hot plasma in the solar outer
atmosphere. The following is a brief summary of the published papers,
abstracts and talks which have been supported. The paper 'Coronal
Structures Observed in X-rays and H-alpha Structures' was published
in the Kofu Symposium proceedings. The study analyzes cool and hot
behavior of two x-ray events, a small flare and a surge. We find that
a large H-alpha surge appears in x-rays as a very weak event, while
a weak H-alpha feature corresponds to the brightest x-ray emission on
the disk at the time of the observation. Calculations of the heating
necessary to produce these signatures, and implications for the
driving and heating mechanisms of flares vs. surges are presented. A
copy of the paper is appended to this report. The paper 'Differential
Magnetic Field Shear in an Active Region' has been published in The
Astrophysical Journal. We have compared the 3D extrapolation of magnetic
fields with the observed coronal structure in an active region. Based
on the fit between observed coronal structure throughout the volume
of the region and the calculated magnetic field configurations, we
propose a differential magnetic field shear model for this active
region. The decreasing field shear in the outer portions of the AR
may indicate a continual relaxation of the magnetic field with time,
corresponding to a net transport of helicity outward. The paper
'Difficulties in Observing Coronal Structure' has been accepted for
publication in the journal Solar Physics. In this paper we discuss the
evidence that the temperature and density structure of the corona are
far more complicated than had previously been thought. The discussion
is based on five studies carried out by our group on coronal plasma
properties, showing that any one x-ray instrument does see all of the
plasma present in the corona, that hot and cool material may appear
to be co-spatial at a given location in the corona, and that simple
magnetic field extrapolations provide only a poor fit to the observed
structure. A copy of the paper is appended to this report.

---------------------------------------------------------
Title: Heliospheric Links Explorer (HELIX)
Authors: Rust, David M.; Crooker, N. U.; Golub, Leon; Hundhausen,
A. J.; Lanzerotti, L. J.; Lazarus, Alan J.; Seehafer, Norbert; Zanetti,
Lawrence J.; Zwickl, Ron W.
1996SPIE.2804...39R Altcode:
The proposed HELIX mission consists of two spacecraft that will
enable stereoscopic imaging of solar mass ejections, starting with
their origins on the Sun and continuing to 1 AU and beyond. With a
complement of telescopes and plasma detectors, the HELIX spacecraft
will test magnetic helicity conservation and other approaches to
understanding the physics of solar mass ejections. The mission will
help explain how and why solar ejections occur and how they evolve in
interplanetary space. 3D images and velocity maps and in-situ space
plasma and magnetic field measurements will allow identification and
tracking of ejected plasma. Detection of eruptions aimed at Earth will
be an immediate practical benefit of the mission. The HELIX mission
should lead to the development of a reliable storm prediction capability
that will be of significant value to communications systems operators,
electric power networks, NASA operators and others.

---------------------------------------------------------
Title: Differential Magnetic Field Shear in an Active Region
Authors: Schmieder, B.; Demoulin, P.; Aulanier, G.; Golub, L.
1996ApJ...467..881S Altcode:
The three-dimensional extrapolation of magnetic field lines from a
magneto gram obtained at Kitt Peak allows us to understand the global
structure of the NOAA active region 6718, as observed in X-rays with the
Normal Incidence X-ray Telescope (NIXT) and in Hα with the Multichannel
Subtractive Double Pass spectrograph (MSDP) in Meudon on 1991 July
11. This active region was in a quiet stage. Bright X-ray loops connect
plages having field strengths of ∼300 G, while Hα fibriles connect
penumbrae having strong spot fields to the surrounding network. Small,
intense X-ray features in the moat region around a large spot, which
could be called X-ray-bright points, are due mainly to the emergence of
magnetic flux and merging of these fields with surrounding ones. A set
of large-scale, sheared X-ray loops is observed in the central part
of the active region. Based on the fit between the observed coronal
structure and the field configurations (and assuming a linear force-free
field), we propose a differential magnetic field shear model for this
active region. The decreasing shear in outer portions of the active
region may indicate a continual relaxation of the magnetic field to
a lower energy state in the progressively older portions of the AR.

---------------------------------------------------------
Title: Structure and dynamics of coronal plasmas
Authors: Golub, Leon
1996sao..reptQ....G Altcode:
Progress for the period July 1995 - June 1996 included work on the
differential magnetic field shear in an active region; observations
and modeling of the solar chromosphere seen in soft X-ray absorption
by NIXT; and modeling magnetic flux emergence. These were the subjects
of three papers. The plans for the current year include projects on
a converging flux model for point-like brightenings around sunspots,
and difficulties in observing coronal structure.

---------------------------------------------------------
Title: TRACE: the Transition Region and Coronal Explorer
Authors: Schrijver, C.; Title, A.; Acton, L.; Bruner, M.; Fischer,
R.; Golub, L.; Harrison, R.; Lemen, J.; Rosner, R.; Scharmer, G.;
Scherrer, P.; Strong, K.; Tarbell, T.; Wolfson, J.
1996AAS...188.6704S Altcode: 1996BAAS...28..934S
The TRACE mission is designed to obtain images of the solar
transition region and corona of unprecedented quality. With these
images we will be able to explore quantitatively the connections
between the photospheric magnetic field and the associated hot and
tenuous structures in the outer atmosphere. The TRACE telescope has
an aperture of 30 cm, and will observe an 8.5 x 8.5 arcminute field of
view with a resolution of one arcsecond. Finely tuned coatings on four
quadrants on the primary and secondary normal--incidence mirrors will
allow observations in narrow EUV and UV spectral bands. The passbands
are set to Fe IX, XII, and XV lines in the EUV band, while filters
allow observations in C IV, Ly alpha , and the UV continuum using
the UV mirror quadrant. The data thus cover temperatures from 10(4)
K up to 10(7) K. The Sun--synchronous orbit allows long intervals of
uninterrupted viewing. Observations at different wavelengths can be
made in rapid succession with an alignment of 0.1 arcsec. Coordinated
observing with TRACE, SoHO and YOHKOH will give us the first opportunity
to observe all temperature regimes in the solar atmosphere, including
magnetograms, simultaneously from space. TRACE is currently scheduled
to be launched in October 1997. More information can be found on the
web at “http://pore1.space.lockheed.com/TRACE/welcome.html”.

---------------------------------------------------------
Title: The Solar X-Ray Corona
Authors: Golub, L.
1996Ap&SS.237...33G Altcode:
The solar corona, and the coronae of solar-type stars, consist of a
low-density magnetized plasma at temperatures exceeding 106
K. The primary coronal emission is therefore in the UV and soft x-ray
range. The observed close connection between solar magnetic fields and
the physical parameters of the corona implies a fundamental role for
the magnetic field in coronal structuring and dynamics. Variability of
the corona occurs on all temporal and spatial scales—at one extreme,
as the result of plasma instabilities, and at the other extreme driven
by the global magnetic flux emergence patterns of the solar cycle.

---------------------------------------------------------
Title: White-Light Reflecting Corona graph for the SWATH Mission
Authors: Smartt, Raymond N.; Dunn, Richard B.; Carmichael, Roger
B.; Gregory, B. Scott; Plum, Douglas W.; Neidig, Donald F.; Golub,
Leon; Bookbinder, Jay A.; Koutchmy, George U.; Nystrom, Serge L.;
Zimmermann, Jean-Paul
1996ASPC...95..531S Altcode: 1996sdit.conf..531S
No abstract at ADS

---------------------------------------------------------
Title: Observations of a Quiescent Prominence Straddling the Solar
Limb during the Total Eclipse of 11 July 1991
Authors: Gaizauskas, V.; Deluca, E.; Golub, L.; Jones, H. P.;
November, L.
1996mpsa.conf..491G Altcode: 1996IAUCo.153..491G
No abstract at ADS

---------------------------------------------------------
Title: Comparison of High Resolution Optical and Soft X-ray Images
of Solar Corona
Authors: Takeda, A.; Kurokawa, H.; Kitai, R.; Ishiura, K.; Golub, L.
1996mpsa.conf..483T Altcode: 1996IAUCo.153..483T
No abstract at ADS

---------------------------------------------------------
Title: The TRACE Mission
Authors: Title, A.; Bruner, M.; Jurcevich, B.; Lemen, J.; Strong,
K.; Tarbell, T.; Wolfson, J.; Golub, L.; Fisher, R.
1995AAS...18710107T Altcode: 1995BAAS...27.1427T
We have seen significant progress in the flight preparation of the
TRACE (Transition Region and Coronal Explorer) instrument during
the last few months. TRACE, approved for 1997 launch, will collect
images of solar plasmas at temperatures from 10(4) to 10(7) K, with
one arc second spatial resolution and excellent temporal resolution
and continuity. TRACE will explore the connections between fine-scale
magnetic fields and plasma structures in the coronal, transition
zone and temperature minimum regions of the sun. The 1997 launch
opportunity allows for collaborative observations from Earth orbit
with the SoHO instruments stationed at L1. Simultaneous observations
including high-resolution images, spectra, and magnetograms are
possible. The 30 cm aperture TRACE telescope uses four normal-incidence
coatings for the EUV and UV on quadrants of the primary and secondary
mirrors. Interference filters further isolate 5 different UV bands. The
images are coaligned and internally stabilized against spacecraft
jitter. A 1024 x 1024 CCD detector collects images over an 8.5 x 8.5
arc minute field-of-view. TRACE is launched on a GSFC SMEX spacecraft
into a Sun-synchronous orbit. It will operate in coordination with
the SoHO Experiment Operations Facility at GSFC. We are committed to
maintaining an publicly accessible data base for TRACE data. Browsing
and data set requesting capabilities will be included at our World
Wide Web site (see http://www.space.lockheed.com/TRACE/welcome.html).

---------------------------------------------------------
Title: Observations and Interpretation of Soft X-Ray Limb Absorption
Seen by the Normal Incidence X-Ray Telescope
Authors: Daw, A.; Deluca, E. E.; Golub, L.
1995ApJ...453..929D Altcode:
The Normal Incidence X-Ray Telescope (NIXT) obtained a unique set of
high-resolution full-disk solar images which were exposed simultaneously
by X-rays in a passband at 63.5 Å and by visible light. The perfect
alignment of a photospheric visible-light image with a coronal
X-ray image enables us to present observations of X-ray intensity
as a function of an accurately determined height above the visible
limb. The height at which the observed X-ray intensity peaks varies
from 4000 km in active regions to 9000 km in quiet regions of the
Sun. The interpretation of the observations stems from the previously
established fact that, for the coronal loops, emission in the NIXT
bandpass peaks sharply just above the footpoints. Because there is
not a sharp peak in the observed X-ray intensity as a function of
off-limb height, we conclude that the loop footpoints, when viewed at
the limb, are obscured by absorption in chromospheric material along
the line of sight. We calculate the X-ray intensity as a function of
height predicted by a number of different idealizations of the solar
atmosphere, and we compare these calculations with the observed X-ray
intensity as a function of height. The calculations use existing coronal
and chromospheric models. In order for the calculations to reproduce
the observed off-limb X-ray intensities, we are forced to assume an
atmosphere in which the footpoints of coronal loops are interspersed
along the line of sight with cooler chromospheric material extending to
heights well above the loop footpoints. We argue that the absorption
coefficient for NIXT X-rays by chromospheric material is roughly
proportional to the neutral hydrogen density, and we estimate an
average neutral hydrogen density and scale height implied by the data.

---------------------------------------------------------
Title: Structure and dynamics of coronal plasmas
Authors: Golub, Leon
1995sao..reptQ....G Altcode:
The Normal Incidence X-ray Telescope (NIXT) obtained a unique set of
high resolution full disk solar images which were exposed simultaneously
by X-rays in a passband at 63.5 A and by visible light. The perfect
alignment of a photospheric visible light image with a coronal X-ray
image enables us to present observations of X-ray intensity vs an
accurately determined height above the visible limb. The height at
which the observed X-ray intensity peak varies from 4000 km in active
regions to 9000 km in quiet regions of the sun. The interpretation
of the observations stems from the previously established fact that,
for the coronal loops, emission in the NIXT bandpass peaks sharply
just above the footpoints. Because there is not a sharp peak in the
observed X-ray intensity vs off limb height, we conclude that the loop
footpoints, when viewed at the limb, are obscured by absorption in
chromospheric material along the line of sight. We calculate the X-ray
intensity vs height predicted by a number of different idealizations
of the solar atmosphere, and we compare these calculations with the
observed X-ray intensity vs height. The calculations use existing
coronal and chromospheric models. In order for the calculations to
reproduce the observed off limb X-ray intensities, we are forced
to assume an atmosphere in which the footpoints of coronal loops are
interspersed along the line of sight with cooler chromospheric material
extending to heights well above the loop footpoints. We argue that the
absorption coefficient for NIXT X-rays by chromospheric material is
roughly proportional to the neutral hydrogen density, and we estimate an
average neutral hydrogen density and scale height implied by the data.

---------------------------------------------------------
Title: The Transition Region and Coronal Explorer (trace)
Authors: Title, A.; Bruner, M.; Jurcevich, B.; Lemen, J.; Strong,
K.; Tarbell, T.; Wolfson, J.; Golub, L.; Bookbinder, J.; Fisher, R.
1995ESASP.376b.505T Altcode: 1995help.confP.505T; 1995soho....2..505T
No abstract at ADS

---------------------------------------------------------
Title: Normal incidence optics for solar coronal imaging
Authors: Spiller, Eberhard; Wilczynski, Janusz S.; Golub, Leon;
Nystrom, George U.; Gullikson, Eric M.; Tarrio, Charles
1995SPIE.2515..136S Altcode:
We have produced two new normal incidence soft x-ray telescope mirrors
coated for lambda equals 63.5 angstrom wavelength: the first with
a focal length f equals 1.5 m and a diameter of 25 cm for the Space
Weather and Terrestrial Hazards (SWATH) satellite and the second (f
equals 2 m, diameter 27.5 cm) for launch by sounding rocket (NIXT). We
describe figuring and polishing of the mirror surfaces and deposition
and testing of the multilayer coatings. Optimization of the mirror
fabrication included grazing incidence x-ray reflectivity for quality
control during polishing. In addition, the substrate and each metal
layer of the Co-C multilayer coating were polished by an ion beam
with in-situ roughness estimation. We explored the possibilities and
limitations of telescopes for shorter wavelengths by coating several
small mirrors covering the lambda equals 45 to 60 angstrom region at
normal incidence and report on their performance.

---------------------------------------------------------
Title: Temperature Structure of the Solar Corona: Comparison of the
NIXT and YOHKOH X-Ray Images
Authors: Yoshida, Tsuyoshi; Tsuneta, Saku; Golub, Leon; Strong, Keith;
Ogawara, Yoshiaki
1995PASJ...47L..15Y Altcode:
Solar soft X-ray images taken simultaneously by the Yohkoh and the
Normal Incidence X-ray Telescope (NIXT) reveal significantly different
coronal structures. Coronal loops are more clearly seen in the Yohkoh
images, and the isolated island-like structures seen in the NIXT image
have been found to correspond to the footpoints of the Yohkoh loops. The
difference is due to the difference in the temperature response of the
telescopes: NIXT is sensitive to temperatures ranging from 0.9 to 3
MK, while Yohkoh is more sensitive to temperatures above 2.5 MK. The
morphological differences reflect the multi-temperature (1--5 MK)
nature of the solar coronal plasmas.

---------------------------------------------------------
Title: NIXT X-ray Bright Point Survey: Building a Better Bright Point
Authors: Wills, M. J.; Hartl, M. D.; Deluca, E. E.; Golub, L.
1995SPD....26..707W Altcode: 1995BAAS...27..966W
No abstract at ADS

---------------------------------------------------------
Title: Recovering the fine structures in solar images
Authors: Karovska, M.; Habbal, S. R.; Golub, L.; DeLuca, E.; Hudson, H.
1994ESASP.373..183K Altcode: 1994soho....3..183K
No abstract at ADS

---------------------------------------------------------
Title: Bright Rims Adjacent to a Quiescent Hα Filament
Authors: Gaizauskas, V.; de Luca, E.; Golub, L.; Jones, H. P.
1994AAS...18512304G Altcode: 1994BAAS...26.1522G
Recent models of filament-formation invoke reconnection between
small-scale magnetic elements adjacent to the polarity inversion line
separating large areas of unipolar magnetic fields. In an attempt to
confirm this process, we examine joint observations of a quiescent
filament straddling the SW limb of the Sun during the total solar
eclipse of 1991 July 11. We test a hypothesis that a signature of the
reconnection process might be carried by the prominent bright rims
beside or enclosed between curved feet, or 'barbs', which connect
the body of the Hα filament to structures near the base of the
atmosphere. We spatially register digitized Hα (ORSO) images of the
filament with coronal (NIXT) images and with photospheric magnetograms
(NSO/KP) to a precision of +/- 2". Our findings relate to five rims,
elongated bright patches in Hα with a maximum length of 20". We find
a better spatial association of the rims with bipolar magnetic elements
(4/5) than with small patches of weakly enhanced soft X-rays (2/4). We
point out that projection effects at these extreme limb positions could
alter these associations. We conclude from these limited 'snapshot'
observations that we are not yet able to decide whether or not bright
rims on quiescent prominences are locations of magnetic reconnection
on a small scale. Because reconnection is highly dynamic, compelling
evidence for or against this process will have to await prolonged
observations at multiple wavelengths in X-rays of a single filament
at high spatial and temporal resolution, such as those envisaged for
the Transition Region and Coronal Explorer (TRACE).

---------------------------------------------------------
Title: Simultaneous High Resolution Coronal and Photospheric
Observations From NIXT and BBSO
Authors: Winebarger, A.; Deluca, E. E.; Golub, L.
1994AAS...185.8605W Altcode: 1994BAAS...26.1464W
High resolution coronal images from the 11 September 1989 flight of the
NIXT (Normal Incidence X-ray Telescope) and a series of simultaneous
high resolution Big Bear Magnetograms are discussed as part of an on
going investigation of X-ray bright points. The NIXT and BBSO images
are aligned and the evolution of the magnetic fields associated with
coronal features were monitored over the experimental time frame. An
analysis of the relationship between the X-ray bright points and
the time resolved BBSO magnetograms is presented. Bright points are
associated with both converging and diverging magnetic bi-poles.

---------------------------------------------------------
Title: The Roots of Coronal Structure in the Sun's Surface
Authors: Golub, Leon; Zirin, Harold; Wang, Haimin
1994SoPh..153..179G Altcode:
We have compared the structures seen on X-ray images obtained by a
flight of the NIXT sounding rocket payload on July 11, 1991 with
near-simultaneous photospheric and chromospheric structures and
magnetic fields observed at Big Bear. The X-ray images reflect
emission of both MgX and FeXVI, formed at 1 × 106 K
and 3 × 106 K, respectively. The brightest Hα sources
correspond to a dying sub-flare and other active region components,
all of which reveal coronal enhancements situated spatially well
above the Hα emission. The largest set of X-ray arches connected
plages of opposite polarity in a large bipolar active region. The
arches appear to lie in a small range of angle in the meridian plane
connecting their footpoints. Sunspots are dark on the surface and in
the corona. For the first time we see an emerging flux region in X-rays
and find the emission extends twice as high as the Hα arches. Many
features which we believe to correspond to `X-ray bright points'
(XBPs) were observed. Whether by resolution or spectral band, the
number detected greatly exceeds that from previous work. All of the
brighter XBPs correspond to bipolar Hα features, while unipolar Hα
bright points are the base of more diffuse comet-like coronal arches,
generally vertical. These diverge from individual features by less than
30°, and give a good measure of what the `canopies' must do. The Hα
data shows that all the Hα features were present the entire day, so
they are not clearly disappearing or reappearing. We find a new class
of XBPs which we call `satellite points', elements of opposite polarity
linked to nearby umbrae by invisible field lines. The satellite points
change rapidly in X-ray brightness during the flight. An M1.9 flare
occurred four hours after the flight; examination of the pre-flare
structures reveals nothing unusual.

---------------------------------------------------------
Title: Coronal Structures Observed in X-rays (NIXT) and H_alpha Surges
Authors: Schmieder, B.; Mouradian, Z.; Golub, L.; Antiochos, S.
1994kofu.symp..317S Altcode:
Ground-based coordinated observations with the Multichannel subtractive
double pass spectrograph (MSDP) and the heliograph in Meudon allowed
us to portray the chromospheric intensity and velocity fields below
coronal structures observed with the Normal Incidence X-ray Telescope
(NIXT). On July 11, 1991 (eclipse day) we have identified in AR 6713
(N38 W 42) the X-ray signatures of the network, subflares, filaments
and surges. The largest H_alpha surge has only weak emission in
X-ray, while a weak H_alpha feature corresponds to a very bright x-ray
subflare. We calculate the emission measures of these events and give
some constraints on the triggering mechanisms of surges.

---------------------------------------------------------
Title: The Three-Dimensional Structures of X-Ray Bright Points
Authors: Parnell, C. E.; Priest, E. R.; Golub, L.
1994SoPh..151...57P Altcode:
Recently, the Converging Flux Model has been proposed for X-ray bright
points and cancelling magnetic features. The aim of this peice of
work is to try and model theoretically specific X-ray bright points
in the framework of the Converging Flux Model. The observational
data used includes a magnetogram showing the normal component of the
magnetic field at the photosphere and a high-resolution soft X-ray
image from NIXT showing the brightenings in the lower solar corona. By
approximating the flux concentrations in the magnetograms with poles
of the appropriate sign and sense, the overlying three-dimensional
potential field structure is calculated. Deduction of plausible motions
of the flux sources are made which produce brightenings of the observed
shape due to reconnection between neighbouring flux regions. Also the
three-dimensional separarix and separator structure and the way the
magnetic field lines reconnect in three dimensions is deduced.

---------------------------------------------------------
Title: Comparison between Cool and Hot Plasma Behaviors of Surges
Authors: Schmieder, B.; Golub, L.; Antiochos, S. K.
1994ApJ...425..326S Altcode:
Ground-based coordinated observations with the Multichannel Subtractive
Double Pass spectrograph (MSDP) allowed us to obtain chromospheric
intensity and velocity field maps below coronal structures during the
launch of the NIXT payload on 1991 July 11 (eclipse day). A large
H-alpha ejection in AR 6713 (N38 W40) was detected during the NIXT
flight. However, only a low level of X-ray emission was associated
with this event. In contrast, bright X-ray emission associated with a
subflare was observed in a nearby active region, but with only a weak
associated ejection in H-alpha. A discussion of both of these events
gives strong constraints on the triggering mechanisms of surges.

---------------------------------------------------------
Title: Loop Models of Low Coronal Structures Observed by the Normal
Incidence X-Ray Telescope (NIXT)
Authors: Peres, G.; Reale, F.; Golub, L.
1994ApJ...422..412P Altcode:
The X-ray pictures obtained with the Normal Incidence X-Ray Telescope
(NIXT), apart from the ubiquitous coronal loops well known from
previous X-ray observations, show a new and peculiar morphology: in
many active regions there are wide and apparently low-lying areas of
intense emission which resemble H alpha plages. By means of hydrostatic
models of coronal arches, we analyze the distribution of temperature,
density, emission measure, and plasma emissivity in the spectral band to
which NIXT is sensitive, and we show that the above morphology can be
explained by the characteristics of high pressure loops having a thin
region of high surface brightness at the base. We therefore propose
that this finding might help to identify high-pressure X-ray emitting
coronal regions in NIXT images, and it is in principle applicable to
any imaging instrument which has high sensitivity to 104 -
106 K plasma within a narrow coronal-temperature passband. As
a more general result of this study, we propose that the comparison
of NIXT observations with models of stationary loops might provide
a new diagnostic: the determination of the loop plasma pressure from
measurements of brightness distribution along the loop.

---------------------------------------------------------
Title: Results from the recent flights of the IBM/SAO x-ray telescopes
Authors: Spiller, Eberhard; Barbee, Troy W.; Golub, Leon; Kalata,
Kenneth; Nystrom, George U.; Viola, A.
1994SPIE.2011..391S Altcode:
The instruments on board our Normal Incidence X-ray Telescopes payload
and the results obtained during the most recent flights will be
described. The payload was launched three times during the 1991 - 1993
period, the last time on April 12, 1993. It contained a main telescope
with an 11 inch diameter multilayer coated mirror for (lambda) equals
63.5 angstroms and photographic film as detector. Smaller telescopes for
either (lambda) equals 304 angstroms or (lambda) equals 193 angstroms
used electronic detection and direct transmission of analog or digital
data to the ground station. The flight on the day of the solar eclipse
in July 1991 gave us an opportunity to perform a soft-ray knife edge
test with the limb of the moon. From the experiment we derive upper
limits for the figure errors of the telescope mirror, and we conclude
that large mirrors with diffraction limited resolution better than
0.01 arcsec can now be fabricated.

---------------------------------------------------------
Title: The NIXT and SWATH Experiments
Authors: Golub, Leon
1994ASPC...68..329G Altcode: 1994sare.conf..329G
No abstract at ADS

---------------------------------------------------------
Title: Investigation relative to the Roentgen Satellite (ROSAT)
Authors: Elvis, Martin S.; Primini, Francis A.; Fabbiano, Guiseppina;
Harris, Daniel E.; Jones-Forman, Christine; Trinchieri, Ginevra;
Golub, Leon; Bookbinder, Jay; Seward, Frederick D.; Zombeck, Martin V.
1994sao..rept.....E Altcode:
Reports include: High Resolution Observations of the Central Region of
M31; The X-ray Emission of Low-X-ray-Luminosity Early-Type Galaxies:
Gas Versus Compact Sources; Interaction Between Cluster Gas and Radio
Features of Cygnus A; Hot Gas and Dark Halos in Early-Type Galaxies;
A Gravitational Lens in X-rays - 0957+461; How Massive are Early-Type
Galaxies?; Three Crab-Like SNR in the Large Magellanic Cloud; and Soft
X-ray Emission from Boundary Layers in Cataclysmic Variables. Papers
submitted to the Astrophysical Journal are attached.

---------------------------------------------------------
Title: Pressure diagnostics of coronal loops observed by NIXT
Authors: Peres, G.; Reale, F.; Golub, L.
1994LNP...432..179P Altcode: 1994LNPM...11..179P
The Normal Incidence X-ray Telescope (NIXT sounding rocket payload —
a set of multilayer telescopes of novel design — provides images of
the corona at sub-arcsec angular resolution in narrow X-ray spectral
bands centered at the wavelengths of particular coronal emission
lines. The NIXT 63.5 angstrom coronal images show the well-known
and ubiquitous coronal loops but also, mostly in active regions,
shallow and bright areas of intense emission not resembling loops. We
have explained such areas within the traditional physics of coronal
loop models as intense emission in the NIXT band coming from a narrow
region at the base of high pressure loops; the particular nature of the
NIXT temperature sensitivity, with its bimodal temperature response,
is the key to detecting such a feature. We discuss the implications
of this finding and, in particular, we show the possibility of new
diagnostics of plasma pressure independent of the traditional one based
on the determination of emission measure. In addition, we show that
there is very little dependence of the spatial distribution of the
X-ray emissivity in the NIXT passband on the details of the spatial
distribution of the heating function.

---------------------------------------------------------
Title: Coronal Structures Observed in X-Rays (NIXT) and Hα Surges
Authors: Schmieder, B.; Mouradian, Z.; Golub, L.; Antiochos, S.
1994emsp.conf..159S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The SWATH Satellite Program
Authors: Bookbinder, J.; Golub, L.; Deluca, E.; Smartt, R.
1993AAS...183.0810B Altcode: 1993BAAS...25R1302B
No abstract at ADS

---------------------------------------------------------
Title: The Coronal Structure above Sunspots and Pores
Authors: Harmon, R.; Rosner, R.; Zirin, H.; Spiller, E.; Golub, L.
1993ApJ...417L..83H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Magnetic Field in the Corona above Sunspots at the Eclipse
of 1991 July 11
Authors: Gary, D. E.; Leblanc, Y.; Dulk, G. A.; Golub, L.
1993ApJ...412..421G Altcode:
A partial solar eclipse and an X-ray image are used to study the
magnetic field as a function of height in the corona above an active
region during the solar eclipse of July 11, 1991. The dominant features
of AR 6718 are two leading spots of positive polarity followed by two
spots of negative polarity about 3 arcmin to the east. Bright radio
emission coincides with the positions of the sunspots, attributable to
a gyroresonance radiation from ambient electrons above the spots. A
simplified model of the source as a function of frequency based on
the interferometer fringe amplitudes is used to obtain brightness
temperature spectra for the emission associated with the sunspots. It
is deduced that the magnetic field strength at the base of the corona
above the leading spots was 1200 G, and about 1100 G above the following
spots. The soft X-ray brightness above the sunspots was very low, about
30 times lower than that of the adjacent plage-associated emission.

---------------------------------------------------------
Title: Heating the Sun's million degree corona.
Authors: Golub, L.
1993Ast....21....4G Altcode:
For decades astronomers have struggled to explain why the Sun's corona
is so much hotter than its surface. Now X-ray observations reveal new
clues about what heats the corona.

---------------------------------------------------------
Title: Normal Incidence X-Ray Telescope Power Spectra of X-Ray
Emission from Solar Active Regions. I. Observations
Authors: Gomez, Daniel O.; Martens, Petrus C. H.; Golub, Leon
1993ApJ...405..767G Altcode:
Fourier analysis is applied to very high resolution image of coronal
active regions obtained by the Normal Incidence X-Ray Telescope is
used to find a broad isotropic power-law spectrum of the spatial
distribution of soft X-ray intensities. Magnetic structures of all
sizes are present down to the resolution limit of the instrument. Power
spectra for the X-ray intensities of a sample of topologically different
active regions are found which fall off with increasing wavenumber
as 1/k-cubed. A model is presented that relates the basic features
of coronal magnetic fluctuations to the subphotospheric hydrodynamic
turbulence that generates them. The model is used to find a theoretical
power spectrum for the X-ray intensity which falls off with increasing
wavenumber as 1/k-cubed. The implications of a turbulent regime in
active regions are discussed.

---------------------------------------------------------
Title: Normal Incidence X-Ray Telescope Power Spectra of X-Ray
Emission from Solar Active Regions. II. Theory
Authors: Gomez, Daniel O.; Martens, Petrus C. H.; Golub, Leon
1993ApJ...405..773G Altcode:
In a previous paper, we used the very high resolution images of coronal
active regions obtained by the Normal Incidence X-Ray Telescope to
study the size distribution of X-ray-emitting structures. A Fourier
analysis of these images showed a broad-band, isotropic, power-law
spectrum for the spatial distribution of soft X-ray intensities. The
presence of a broad-band spectrum indicates that magnetic structures
of all sizes are 3" present, at least down to the resolution limit
of the instrument, which is about ¾". In the present paper, we
present a model that relates the basic features of coronal magnetic
fluctuations to the subphotospheric hydrodynamic turbulence that
generates them. The main result of this paper is that from this
model we obtain a theoretical power spectrum for the X-ray intensity,
which falls off with increasing wavenumber as k-3, fitting
remarkably well the observed spectra that we obtained from a sample
of topologically different active regions. We speculate that the
nonlinear interactions of these externally driven fluctuations will
contribute to establish a magnetohydrodynamic turbulent regime in the
corona. We suggest that the bulk of the energy delivered to the corona
from footpoint motions directly cascades down to very microscopic length
scales, where it efficiently dissipates and heats the plasma. However,
since the wavenumber range associated with the cascade and dissipation
regions are still beyond present-day spatial resolution limits, the
presence of a turbulent regime cannot be observationally confirmed.

---------------------------------------------------------
Title: NIXT High Resolution Observations
Authors: Golub, L.
1993ASSL..183...71G Altcode: 1993pssc.symp...71G
No abstract at ADS

---------------------------------------------------------
Title: X-Ray Observations of Sunspot Penumbral Structure
Authors: Sams, B. J., III; Golub, L.; Weiss, N. O.
1992ApJ...399..313S Altcode:
High-resolution coronal observations with the Normal Incidence X-ray
Telescope (NIXT) reveal previously unobserved structure in the magnetic
fields above a sunspot. The X-ray images are precisely aligned with
a continuum photospheric image taken at the same time. The X-ray
brightness traces magnetic field lines and shows: (1) that none of
the bright loops originate in the spot umbra and (2) that some field
lines emerging from the inner penumbra connect to regions far away
from the spot. Such large-scale structures must remain distinct from
the shallowly inclined fields in the outer penumbra. In particular,
they cannot be involved in any interchange between the bright and dark
filaments. This imposes constraints on models of penumbral convection.

---------------------------------------------------------
Title: Underneath coronal loops: MSDP observations coordinated with
SERTS 4 and NIXT flights.
Authors: Schmieder, B.; Mein, N.; Golub, L.; Davila, J. M.; Thomas,
R.; Brosius, J.
1992ESASP.348..257S Altcode: 1992cscl.work..257S
Ground-based coordinated observations with the multichannel subtractive
double pass spectrograph (MSDP) allowed to portray the chromospheric
intensity and velocity fields below coronal structures during recent
launchs of sounding rockets. During SERTS 4 observations (May 7,
1991), two different active regions presenting flare and filament have
been coaligned with UV structures. In July 11, 1991 (eclipse day)
large Hα ejection material in AR 6713 was detected during the NIXT
flight. Preliminary results are displayed.

---------------------------------------------------------
Title: Imaging performance of multilayer x-ray mirrors
Authors: Spiller, Eberhard; Wilczynski, Janusz; Stearns, Daniel;
Golub, Leon; Nystrom, George
1992ApPhL..61.1481S Altcode:
We analyze soft X-ray images of the solar corona, obtained on the day
of the solar eclipse in July 1991, and find that the deviations of
our telescope mirror from the perfect surface are less than 1 A for
spatial periods between 1 micron and 1 mm. Our thin film deposition
technique allows us to reduce errors over larger periods to the 1
A level. Thus, we are able to produce larger (diameter over 20 cm)
X-ray mirrors with diffraction limited resolution below 0.01 arcsec.

---------------------------------------------------------
Title: Coronal Loops: Current-based Heating Processes
Authors: Beaufume, P.; Coppi, B.; Golub, L.
1992ApJ...393..396B Altcode:
Based on new observations, a theoretical model of magnetic-field
related heating processes in the solar corona is given. In this model,
field-aligned currents are induced along coronal loops in thin current
sheaths. Excitation of instabilities involving magnetic reconnection
converts the energy associated with the current-related magnetic field
directly into particle energy, where the heating process proceeds
via short bursts corresponding to an intermittent disruption of the
current sheath configuration. Because of the relatively low transverse
thermal conduction, only a small fraction of the loop volume is heated
to a much higher temperature than the average value. This is consistent
with experimental observations of low filling factors of hot plasmas in
coronal loops. Thus the model involves a repeated sequence of dynamic
events taking into account the observed loop topology, the differential
emission measure distribution in the 10 exp 6 - 10 exp 7 K range,
the energy balance requirements in the loop, and the probable duty
cycles involved in the heating processes.

---------------------------------------------------------
Title: How Coronal Loops Brighten: Observational Results from the
Normal Incidence X-Ray Telescope Sounding Rocket Experiment
Authors: Golub, L.; Harmon, R.; Rashid, R.; Spiller, E.
1992AAS...180.4008G Altcode: 1992BAAS...24..793G
No abstract at ADS

---------------------------------------------------------
Title: Obtaining high resolution XUV coronal images.
Authors: Golub, L.; Spiller, E.
1992ESASP.344..221G Altcode: 1992spai.rept..221G
Photos obtained during three flights of our 11-inch diameter normal
incident soft X-ray telescope are analyzed and the data are compared
to the results expected from tests of the mirror surfaces. Multilayer
coated X-ray telescopes have the potential for 0.01 arcsec resolution
and the authors are optimistic that such high quality mirrors can be
built. Some of the factors which enter into the performance actually
achieved in practice are: quality of the mirror substrate, quality of
the multilayer coating and number of photons collected. The authors'
measurements of multilayer mirrors show that the actual performance
achieved in the solar x-ray images demonstrates a reduction in the
scattering compared to that calculated from the topography of the top
surface of the multilayer.

---------------------------------------------------------
Title: Structure of the Solar X-ray Corona (Invited Review)
Authors: Golub, L.
1992ASPC...26..193G Altcode: 1992csss....7..193G
No abstract at ADS

---------------------------------------------------------
Title: The X-ray ultraviolet imager for the orbiting solar laboratory
Authors: Antonucci, Ester; Malvezzi, Marco; Ciminiera, Luigi; Angrilli,
Francesco; Bruner, Marilyn E.; Perona, Giovanni; Adele Dodero, Maria;
Evans, Brian L.; Golub, Leon; Landini, Massimo; Noci, Giancarlo;
McWhirter, Peter; Fossi, Brunella Monsignori; Poletto, Giannina;
Neidig, Donald F.; Schmidt, Wolfgang K. H.; Thomas, Roger J.;
Tondello, Giuseppe
1992AIPC..267..126A Altcode: 1992ecsa.work..126A
A normal incidence multimirror telescope, the X-ray Ultraviolet
Imager, for high resolution imaging of the solar atmosphere in the
soft X-ray/XUV region, is being developed as part of the scientific
payload of the NASA Orbiting Solar Laboratory. The X-ray Ultraviolet
Imager is formed by two units: a high resolution telescope (0.25
arcsec pixel size and 8×8 arcmin2 field of view) and a wide field one
(2.3 arcsec pixel size and 5×5 solar radii2 field of view). The two
systems complement each other and allow a full coverage of solar
features from the small scale (200 km on the sun) to the global
phenomena. Each system consists of 8 channels with multilayer mirrors,
imaging at different wavelengths. In each channel the mirror coating
is optimized to select a narrow spectroscopic window corresponding to
an intense line in the region 40-400 A˚. In order to provide imaging
and temperature diagnostics from the chromosphere to the upper corona,
8 wavelengths are chosen to cover the broad temperature range from 105
to 107 K. Four images, two high resolution and two full disk ones,
are simultaneously obtained by the X-ray Ultraviolet Imager, at a
cadence which in flares can be of 0.4-1 s.

---------------------------------------------------------
Title: Hydrostatic models of X-ray coronal loops observed by NIXT
Authors: Peres, G.; Reale, F.; Golub, Leon
1992AIPC..267..136P Altcode: 1992ecsa.work..136P
Observations made with the Normal Incidence X-ray Telescope (NIXT)
have shown that some X-ray emitting structures observed with NIXT
resemble very closely the corresponding Hα plages. We have used
hydrostatic models of coronal loops to explain such observations as
strong emission from the lower section of high-presssure coronal arches.

---------------------------------------------------------
Title: Normal incidence soft x-ray lambda=63.5 A telescope of 1991
Authors: Spiller, Eberhard; Wilczynski, Janusz S.; Golub, Leon;
Nystrom, George U.
1992SPIE.1546..168S Altcode: 1992SPIE.2011..168S
Modifications to our multilayer coated normal incidence telescope
for (lambda) equals 63.5 angstrom since its last flight in 1989 are
described. The purpose of the changes was to increase the photon
flux of the detector by increasing the mirror reflectivity, area,
and uniformity and by the use of light blocking filters with higher
x-ray transmission. First results from the 1991 launch of the telescope
are described.

---------------------------------------------------------
Title: High resolution observations of the solar corona
Authors: Gomez, D.; Golub, L.
1992HiA.....9..659G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: High resolution observations of the solar corona
Authors: Gomez, D.; Golub, L.
1992MmSAI..63..591G Altcode:
The Normal Incidence X-ray Telescope has recently obtained
sub-arcsecond images of the solar corona in a series of successful
rocket flights. Coronal loops are found to present a highly
fibrilated internal structure, down to the spatial resolution of the
instrument. The footpoints of coronal loops lie in areas of enhanced
chromospheric emission, like network, plage or sunspot penumbrae. No
hot loops have been found terminating in sunspot umbrae. Several
flare events have also been detected during these flights, all of
them showing a highly tangled topological structure at small scales. A
Fourier analysis performed on a number of coronal active region images
yields a broadband power spectrum for the spatial distribution of
soft X-ray intensity, which can be interpreted by the presence of a
turbulent regime inside coronal loops.

---------------------------------------------------------
Title: Flares Observed by the Normal Incidence X-Ray Telescope on
1989 September 11
Authors: Herant, M.; Pardo, F.; Spiller, E.; Golub, L.
1991ApJ...376..797H Altcode:
Two solar flare events have been observed in soft X-rays during a
sounding-rocket flight of the Normal-Incidence X-ray Telescope payload
on September 11, 1989. The flare in X-rays involves a single bright loop
crossing the neutral line, and having its footpoints at the southern
ends of the ribbons; this loop accounts for more than 66 percent
of the emission. Within the remainder of each of the flare ribbons,
a complex coronal structure is also observed to be interacting with
the main flare loop. A second event, in an active region at the limb,
has a strong correlation with H-alpha images obtained at the same
time. This indicates the coexistence, and indeed the close proximity,
of coronal and chromospheric temperature material. Interpretations of
this phenomenon are discussed.

---------------------------------------------------------
Title: Normal-incidence soft X-ray telescopes.
Authors: Spiller, Eberhard; McCorkle, R. A.; Wilczynski, J. S.; Golub,
Leon; Nystrom, G.; Takacs, P. Z.; Welch, C.
1991OptEn..30.1109S Altcode:
Photos obtained during 5 min of observation time from the flight of
a 25 cm-diam normal-incidence soft X-ray (λ = 63.5Å) telescope are
analyzed and the data are compared to the results expected from tests of
the mirror surfaces. These tests cover a range of spatial periods from
25 cm to 1Å. The photos demonstrate a resolution close to the photon
shot noise limit and a reduction in the scattering of the multilayer
mirror compared to a single surface for scattering angles above 1',
corresponding to surface irregularities with spatial periods below 10
μm. The results are used to predict the possible performance of future
telescopes. The authors conclude that sounding rocket observations
might be able to reach a resolution around 0.1″

---------------------------------------------------------
Title: A Dynamical Model for Heating of Coronal Loops
Authors: Beaufumê, P.; Coppi, B.; Golub, L.
1991BAAS...23.1059B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Imaging performance and tests of soft x-ray telescopes
Authors: Spiller, Eberhard; McCorkle, R.; Wilczynski, Janusz S.;
Golub, Leon; Nystrom, George U.; Takacs, Peter Z.; Welch, Charles W.
1991SPIE.1343..134S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spectra of MHD Turbulence in Coronal Active Regions (With
3 Figures)
Authors: Gomez, D.; Martens, P.; Herant, M.; Pardo, F.; Golub, L.
1991mcch.conf..124G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray Observations of Global Solar Activity
Authors: Golub, L.
1991LNP...387..271G Altcode: 1991fpsa.conf..271G
High resolution observations of the Solar corona, mainly from the Skylab
missions in 1973-74, have shown that the x-ray corona is variable on
all observable temporal and spatial scales. Variability which has
been observed ranges from x-ray bright point flares, with sizes of
a few arcseconds and rise times of tens of seconds, to large scale
structure evolution on time scales of months to years and size scales
of a Solar radius. In this paper we present a sampling of the data,
up to and including the most recent high resolution results from the
NIXT rocket, in order to discuss the important new contributions which
will be made by the Solar-A instruments.

---------------------------------------------------------
Title: Very High Resolution Solar X-ray Imaging (With 6 Figures)
Authors: Golub, L.
1991mcch.conf..115G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: SXT Observations of MHD Turbulance in Active Regions
Authors: Martens, P. C. H.; Gómez, D. O.; Slater, G.; Golub, L.
1991LNP...387..291M Altcode: 1991fpsa.conf..291M
The recent discovery from NIXT images that the Fourier transform of
the X-ray intensity in active regions is a power-law, is consistent
with 2D MHD turbulence theory. We briefly discuss this theory and its
application to the heating of the solar corona. Then we demonstrate that
SXT will be capable of observing similar spectra, even in compressed
data-transfer mode between flare observations. Finally we discuss
observing plans for verification of the hypothesis of coronal heating
through turbulent MHD cascades.

---------------------------------------------------------
Title: Long- and short-timescale variability of magnetic activity
on the BY Dra star BD + 26°730
Authors: Saar, S. H.; Golub, L.; Bopp, B.; Herbst, W.; Huovelin, J.
1990ESASP.310..431S Altcode: 1990eaia.conf..431S
No abstract at ADS

---------------------------------------------------------
Title: Filters for soft X-ray solar telescopes.
Authors: Spiller, Eberhard; Grebe, Kurt; Golub, Leon
1990OptEn..29..625S Altcode:
Soft X-ray telescopes require filters that block visible and infrared
light and have good soft X-ray transmission. The optical properties
of possible materials are discussed, and the fabrication and testing
methods for the filters used in a 10-inch normal incidence telescope
for λ = 63 Å are described. The best performances in the λ= 44 -
114 Å wavelength range are obtained with foils of carbon and rhodium.

---------------------------------------------------------
Title: Filters for soft x-ray solar telescopes
Authors: Golub, Leon
1990OptEn..29..625G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The XUV imager for the OSL.
Authors: Landini, M.; Noci, G.; Antonucci, E.; Bruner, M. E.; Evans,
B. L.; Golub, L.; Malvezzi, M.; McWhirter, R. W.; Monsignori Fossi,
B. C.; Poletto, G.; Neidig, D.; Perona, G.; Thomas, R.; Tondello, G.
1990BAAS...22.1148L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sub-arcsecond observations of the solar X-ray corona
Authors: Golub, L.; Herant, M.; Kalata, K.; Lovas, I.; Nystrom, G.;
Pardo, F.; Spiller, E.; Wilczynski, J.
1990Natur.344..842G Altcode:
SOFT X-ray observations are recognized as the best way to study the
solar corona, as they are largely free of contaminating emission from
other temperature regimes. They provide the only available method
for seeing the corona on the disk, thereby avoiding the line-of-sight
integration effects which are troublesome in limb observations. Here we
present results from a high-resolution multilayer-coated X-ray imaging
telescope, part of the Normal Incidence X-ray Telescope sounding rocket
payload. From a flight at 16:35 UT on 11 September 1989 we obtained
40 images of the solar X-ray corona, with spatial resolution up to
0.75 arcsec. Images of the peak of a two-ribbon flare showed detailed
structure within each ribbon, as well as the expected bright arches of
emission connecting the ribbons. Active regions showed structure at a
scale of 0.75 arcsec that was not visible in our 2-arcsec images taken
during the same flight. The number of X-ray bright points1
is small, consistent with predictions based on the previous solar
cycle2. The topology of the magnetic structure is complex
and highly tangled, implying that the magnetic complexity of the
photosphere is paralleled in the corona.

---------------------------------------------------------
Title: Observational Evidence for Heating through MHD Turbulence in
Coronal Active Regions
Authors: Gomez, D.; Martens, P. C. H.; Herant, M.; Golub, L.
1990BAAS...22Q.796G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: NIXT Observations of the June 23 1988 Flare and their
Theoretical Interpretation
Authors: Martens, P. C. H.; Golub, L.; Herant, M.
1990ppsa.conf..153M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sub-Arcsecond Observations of the Solar X-ray Corona
Authors: Golub, L.; Spiller, E.
1989BAAS...21Q1150G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comments on the Observability of Coronal Variations
Authors: Golub, L.; Hartquist, T. W.; Quillen, A. C.
1989SoPh..122..245G Altcode:
We discuss the observable variability of spectral lines in the soft
X-ray and XUV region. Rapid variability of coronal emission, both in
flaring and non-flaring structures has been reported and is particularly
prominent when high spatial resolution is available. Examination
of the ionization and recombination time-scales for the formation
and removal of ions with prominent solar emission lines shows that,
even though ionization equilibrium generally prevails, the observable
variability time-scales are often limited by these atomic processes,
independent of the physical process which is causing the change in
the solar atmosphere. Rapid heating can lead to an initial freezing-in
of abundances of some ions; observations of at least one low- and one
high-excitation line from such an ion would permit studies of the time
evolution of the emission measure and temperature. In a very limited
number of cases, rapid cooling leads to freezing-in of the abundance
of an ion and observations of a low-excitation line of this ion will
not yield accurate information about the thermal evolution. Thus,
future observations of Mgx 609 Å should be augmented by simultaneous
observation at another wavelength, such as 63 Å. In addition, with
the ability to produce images in isolated spectral lines it becomes
possible to select those for which rapid variability is observable,
such asOVII, rather than lines which were selected on the basis of
previous hardware constraints, such asOVII.

---------------------------------------------------------
Title: X-ray bright points and He i λ 10830 dark points
Authors: Golub, L.; Harvey, K. L.; Herant, M.; Webb, D. F.
1989SoPh..124..211G Altcode:
Using near-simultaneous full disk solar X-ray images and HeI λ10830
spectroheliograms from three rocket flights, we compare dark points
identified on the HeI maps with X-ray bright points identified on the
X-ray images. We find that for the largest and most obvious features
there is a strong correlation: most HeI dark points correspond to
X-ray bright points. However, about two-thirds of the X-ray bright
points were not identified on the basis of the helium data alone. Once
an X-ray feature is identified it is almost always possible to find
an underlying dark patch of enhanced HeI absorption which, however,
would not a priori have been selected as a dark point. Therefore, the
HeI dark points, using current selection criteria, cannot be used as
a one-to-one proxy for the X-ray data. HeI dark points do, however,
identify the locations of the stronger X-ray bright points.

---------------------------------------------------------
Title: A Study of Dissipative Structures in the Solar Corona with
High-Resolution NIXT Images
Authors: Gomez, D.; Martens, P. C. H.; Golub, L.
1989BAAS...21R1150G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray bright points and He I lambda 10830 dark points
Authors: Golub, L.; Harvey, K. L.; Herant, M.; Webb, D. F.
1989sxsr.rept.....G Altcode:
Using near-simultaneous full disk Solar X-ray images and He I 10830
lambda, spectroheliograms from three recent rocket flights, dark
points identified on the He I maps were compared with X-ray bright
points identified on the X-ray images. It was found that for the
largest and most obvious features there is a strong correlation:
most He I dark points correspond to X-ray bright points. However,
about 2/3 of the X-ray bright points were not identified on the basis
of the helium data alone. Once an X-ray feature is identified it is
almost always possible to find an underlying dark patch of enhanced He
I absorption which, however, would not a priori have been selected as
a dark point. Therefore, the He I dark points, using current selection
criteria, cannot be used as a one-to-one proxy for the X-ray data. He I
dark points do, however, identify the locations of the stronger X-ray
bright points.

---------------------------------------------------------
Title: Fabrication and testing of large area multilayer coated
x-ray optics
Authors: Spiller, Eberhard; Golub, Leon
1989ApOpt..28.2969S Altcode:
The procedures developed for the production and testing of multilayer
X-ray mirrors on large figured optical surfaces are discussed. Methods
which are generally useful for characterizing the performance of such
optics are presented, as well as specific results from the production
of a 25-cm-diameter Ritchey-Chretien telescope for a wavelength of
63.5 A. The latter is a two-mirror system, which places additional
stringent requirements upon the accuracy and quality of the coatings.

---------------------------------------------------------
Title: Analysis of the 23 June 1988 flare using normal incidence
x-ray telescope multilayer x-ray images
Authors: Golub, Leon; Herant, Marc
1989SPIE.1160..629G Altcode: 1989xeoa.conf..629G
Results obtained during the June 23, 1988 flight of the normal incidence
X-ray telescope (NIXT) sounding rocket payload are reported. The
telescope primary is 25 cm in diameter, in a 750 cm e.f.l. (f/30)
Ritchey-Chretien configuration, with multilayer coatings on the optics
designed to image the Fe XVI and Mg X coronal emission lines near
63.5 A. Images of the onset phase of a large (M8) Solar flare were
recorded during the flight on a modified T-max 400 film manufactured
by Kodak. Some of the results obtained by comparison of the NIXT data
with ground-based observations of the sun obtained simultaneously to
the flight are also reported.

---------------------------------------------------------
Title: Double crystal multilayer x-ray monochromator
Authors: Golub, Leon; Quillen, Alice C.; Spiller, Eberhard
1989SPIE.1160..176G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Filters for soft X-ray solar telescopes.
Authors: Spiller, E.; Grebe, K.; Golub, L.
1989SPIE.1160...66S Altcode: 1989xeoa.conf...66S
Soft X-ray telescopes require filters that block visible and infrared
light and have good soft X-ray transmission. The optical properties
of possible materials are discussed and the fabrication and testing
methods for the filters used in a 10 inch normal incidence telescope
for λ = 63 Å are described. The best performances in the λ = 44 -
114 Å wavelengths range is obtained with foils of carbon and rhodium.

---------------------------------------------------------
Title: A Normal Incidence X-ray Telescope (NIXT) sounding rocket
payload
Authors: Golub, Leon
1989sao..reptQ....G Altcode:
Work on the High Resolution X-ray (HRX) Detector Program is
described. In the laboratory and flight programs, multiple copies of
a general purpose set of electronics which control the camera, signal
processing and data acquisition, were constructed. A typical system
consists of a phosphor convertor, image intensifier, a fiber optics
coupler, a charge coupled device (CCD) readout, and a set of camera,
signal processing and memory electronics. An initial rocket detector
prototype camera was tested in flight and performed perfectly. An
advanced prototype detector system was incorporated on another rocket
flight, in which a high resolution heterojunction vidicon tube was
used as the readout device for the H(alpha) telescope. The camera
electronics for this tube were built in-house and included in the
flight electronics. Performance of this detector system was 100 percent
satisfactory. The laboratory X-ray system for operation on the ground
is also described.

---------------------------------------------------------
Title: Solar and stellar coronal plasmas
Authors: Golub, Leon
1989sao..reptR....G Altcode:
Progress in observational, theoretical, and radio studies of coronal
plasmas is summarized. Specifically work completed in the area of solar
and stellar magnetic fields, related photospheric phenomena and the
relationships between magnetism, rotation, coronal and chromospheric
emission in solar-like stars is described. Also outlined are theoretical
studies carried out in the following areas, among others: (1) neutral
beams as the dominant energy transport mechanism in two ribbon-flares;
(2) magneto hydrodynamic and circuit models for filament eruptions; and
(3) studies of radio emission mechanisms in transient events. Finally,
radio observations designed for coronal activity studies of the sun
and of solar-type coronae are described. A bibliography of publications
and talks is provided along with reprints of selected articles.

---------------------------------------------------------
Title: High-resolution imaging of the solar corona.
Authors: Golub, L.
1989BAAS...21..848G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The M8.1 Flare of 1988JUN23 - Part One
Authors: Herant, M.; Golub, L.; Neidig, D. F.
1989SoPh..124..145H Altcode:
Hα observations of two-ribbon flares often show secondary brightenings
which are not directly spatially connected with the main center of
activity but which are correlated in time with the primary impulsive
flare. We present here a mechanism which explains these secondary
brightenings via the reconnection of magnetic loops which are tied to
only one of the two ribbons, in contrast with the loops responsible for
the main flare which are tied to both ribbons. The distant footpoint is
then interpreted as the site of the secondary brightening. We apply our
model to the two-ribbon flare of 17:52 UT, 23 June, 1988, which started
during the rocket flight of the Normal Incidence X-ray Telescope.

---------------------------------------------------------
Title: High-Resolution Imaging of the Solar Corona
Authors: Golub, L.
1989BAAS...21R.848G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An Intensified CCD EUV Camera for the SOHO/CDS Experiment
Authors: Golub, L.; Kalata, K.; Poland, A. I.; Thomas, R. J.
1988BAAS...20..980G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Multi-Wavelength Observations of the 23 June 1745UT M8 Flare
Authors: Herant, M.; Golub, L.; Mickey, D.; Neidig, D.; Slater, G.
1988BAAS...20R.977H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A high resolution phosphor screen for XUV detectors
Authors: Sams, B. J., III; Golub, L.; Kalata, K.
1988JPhE...21..302S Altcode:
The paper presents an XUV detector with a spatial resolution of about 6
microns designed to fly on the normal incidence X-ray telescope (NIXT)
rocket package. The telescope is a 254 mm diameter Ritchey-Chretien
system which relies on unusually high accuracy multilayer coatings
to image active regions on the sun. The coatings are reflective in a
narrow band centered on a wavelength near 6.3 nm; thus the detector's
job is to convert the XUV image into an electronic format which can
be stored on tape or relayed to the ground via telemetry. This paper
is primarily concerned with how the X-rays are converted into a very
high resolution visible light image which can be sensed and read out
by the image processing electronics.

---------------------------------------------------------
Title: Conference on X-Ray Instrumentation in Astronomy,
II. Proceedings of the Meeting, San Diego, CA, Aug. 15-17, 1988.
Authors: Golub, Leon
1988SPIE..982.....G Altcode:
Various papers on X-ray instrumentation in astronomy are
presented. Individual topics addressed include: concentrating
hard X-ray collector, advanced X-ray Astrophysics Facility high
resolution camera, Fano-noise-limited CCDs, linear CCD with enhanced
X-ray quantum efficiency, advances in microchannel plate detectors,
X-ray imaging spectroscopy with EEV CCDs, large aperture imaging gas
scintillation proportional counter, all-sky monitor for the X-ray
Timing Explorer, and miniature satellite technology capabilities for
space astronomy. Also discussed are: high-resolution X-ray spectroscopy
using microcalorimeters, high-throughput X-ray astrophysics cornerstone,
gas mixtures for X-ray proportional counters, transmission grating
spectrometer for SPEKTROSAT, efficiency of X-ray reflection gratings,
soft X-ray spectrographs for solar observations, observability of
coronal variations, Berkeley extreme-UV calibration facility, SURF-II
radiometric instrumentation calibration facility, and evaluation of
toroidal gratings in the EUV.

---------------------------------------------------------
Title: Comments on the observability of coronal variations.
Authors: Golub, Leon; Quillen, Alice C.; Hartquist, Thomas W.
1988SPIE..982..311G Altcode: 1988xia..conf..311G
The authors discuss the possibilities opened up by the newly-available
soft X-ray and XUV multilayer coated optics for observations of
the solar outer atmosphere and corona. Presently available material
combinations and the achievable quality of coatings provide basic
limitations to the possible spectral bands which can be observed. The
spectral regions within which solar emission lines are formed are
compared with the available multilayer passbands in a discussion of
the types of instruments which one can consider building. In addition,
the authors discuss briefly the possible spectral lines which are of
interest for studying the various temperature regimes and variability
time constants which are known to be present in the solar atmosphere.

---------------------------------------------------------
Title: Design considerations for soft X-ray television imaging
detectors.
Authors: Kalata, Kenneth; Golub, Leon
1988SPIE..982...64K Altcode: 1988xia..conf...64K
Television sensors such as CCD's and vidicons can be coupled to
convertors and (typically) image intensifiers to obtain active areas,
high flux capabilities, quantum efficiency, high time resolution,
or ease of construction, and operation that may not be obtained with
a directly illuminated sensor in the X-ray and XUV range. A general
purpose system which makes use of these capabilities for a number of
applications is described. Some of the capabilities and properties of
this type of system are discussed, as are some of the considerations
that should be kept in mind when configuring a system of this type.

---------------------------------------------------------
Title: Rapid, Low-Level X-Ray Variability in Active Late-Type Dwarfs
Authors: Ambruster, Carol W.; Sciortino, Salvatore; Golub, L.
1987ApJS...65..273A Altcode:
The authors report the detection of rapid (a few hundred to &gt;1000 s)
quiescent variability, at ≥99% significance, in 24 of 34 Einstein IPC
observations of 19 active K and M dwarfs. The IPC light curve and a plot
of the variability analysis (using a new, statistically rigorous form of
χ2 analysis) are given for each observation. The quiescent
fluctuations appear not to fall on an extension of the N(S) curve for
stellar X-ray flares. The authors discuss solar analogs and the recent
suggestions that low-level flaring heats quiescent X-ray coronae.

---------------------------------------------------------
Title: High Resolution Imaging X-ray Detector
Authors: Golub, L.; Kalata, K.
1987BAAS...19.1136G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comparison of Predicted vs. Measured Stellar Magnetic Fields
Authors: Quillen, A.; Golub, L.; Harnden, F. R., Jr.; Saar, S.
1987BAAS...19.1027Q Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A normal incidence high resolution X-ray telescope for solar
coronal observations
Authors: Golub, Leon
1987sao..reptS....G Altcode:
The preflight preparation of the multilayer mirror fabrication
and testing, integration and testing, and WSMR activities are
described. Post-flight analysis shows that all payload systems and
subsystems performed well within acceptable limits, with the sole
exception of the light-blocking prefilters. Suggested corrective
actions were discussed. Refurbishment and reflight are then described.

---------------------------------------------------------
Title: Einstein Observatory Survey of X-Ray Emission from Solar-Type
Stars: The Late F and G Dwarf Stars
Authors: Maggio, A.; Sciortino, S.; Vaiana, G. S.; Majer, P.;
Bookbinder, J.; Golub, L.; Harnden, F. R., Jr.; Rosner, R.
1987ApJ...315..687M Altcode:
Results of a volume-limited X-ray survey of stars of luminosity classes
IV and V in the spectral range F7-G9 observed with the Einstein
Observatory are presented. Using survival analysis techniques, the
stellar X-ray luminosity function in the 0.15-4.0 keV energy band for
both single and multiple sources. It is shown that the difference in
X-ray luminosity between these two classes of sources is consistent
with the superposition of individual components in multiple-component
systems, whose X-ray properties are similar to those of the
single-component sources. The X-ray emission of the stars in our sample
is well correlated with their chromospheric CA II H-K line emission
and with their projected equatorial rotational velocity. Comparison
of the X-ray luminosity function constructed for the sample of the dG
stars of the local population with the corresponding functions derived
elsewhere for the Hyades, the Pleiades, and the Orion Ic open cluster
confirms that the level of X-ray emission decreases with stellar age.

---------------------------------------------------------
Title: High resolution imaging detector for use with a soft X-ray
telescope.
Authors: Golub, Leon; Kalata, Kenneth
1987SPIE..733..533G Altcode:
An advanced extremely high-resolution telescope utilizing multilayer
coated optics for imaging in the soft X-ray regime is being developed
as well as a high-efficiency electronic detector system capable of
meeting all of the stringent requirements of coronal studies. The
construction of a 2048 x 2048 system with a pixel size of 5 microns,
capable of handling count rates up to a few x 100,000 cts/s in the
photon counting mode, and substantially higher rates in the A/D mode is
discussed. The current status of the development program is discussed
and results are presented.

---------------------------------------------------------
Title: A normal incidence X-ray telescope
Authors: Golub, Leon
1987sao..reptR....G Altcode:
The postflight performance evaluation of the X-ray telescope was
summarized. All payload systems and subsystems performed well within
acceptable limits, with the sole exception of the light-blocking
prefilters. Launch, flight and recovery were performed in a fully
satisfactory manner. The payload was recovered in a timely manner and in
excellent condition. The prefilter performance analysis showed that no
X-ray images were detected on the processed flight film. Recommendations
for improved performance are listed.

---------------------------------------------------------
Title: Magnetogram and soft X-ray comparisons of XBP and ER.
Authors: Golub, Leon; Harvey, Karen L.; Webb, David F.
1986NASCP2442..365G Altcode: 1986copp.nasa..365G
The potential importance of the smallest emerging flux regions on the
sun was discussed in numerous publications. The association between the
objects seen in ground-based data, such as high resolution magnetrons
or H alpha and soft X-ray data has produced results which are often
contradictory. In the hope of resolving the present impasse, as much
simultaneous soft X-ray and magnetogram data as possible were assembled
in order to clarify the situation. It was found that separation of
magnetic features into chance encounters and emerging flux makes some
difference in overlapp with X-ray bright points (XBPs), although the
effect is not overwhelming. The difference in solar cycle dependence
between XBP and ephemeral regions is not explainable in terms of
the results.

---------------------------------------------------------
Title: Rapid X-ray Variability of Quiescent Late-Type Dwarfs:
Implications for Coronal Heating
Authors: Ambruster, C. W.; Sciortino, S.; Golub, L.
1986BAAS...18..985A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Rapid X-Ray Variability in Einstein Observations of K and
M Dwarfs
Authors: Ambruster, C.; Sciortino, S.; Golub, L.
1986LNP...254..219A Altcode: 1986csss....4..219A
No abstract at ADS

---------------------------------------------------------
Title: X-Ray Spectra and the Rotation-Activity Connection of RS
Canum Venaticorum Binaries
Authors: Majer, P.; Schmitt, J. H. M. M.; Golub, L.; Harnden, F. R.,
Jr.; Rosner, R.
1986ApJ...300..360M Altcode:
Results are presented from a survey of RS CVn binaries which were
observed with the imaging proportional counter (IPC) on board the
Einstein Observatory. Spectral analyses of the IPC pulse height spectra
show that the coronae of RS CVn binaries always contain hot gas with
temperatures in excess of 10 to the 7th K, similar to active late-type
main-sequence stars, and that at least two temperature components
are necessary to account for the higher quality IPC spectra (when
absorption is unimportant). It is argued that these bimodal temperature
distributions found by the IPC are indicative of true distributions
of emission measure versus temperature that are continuous (just as
is the case of magnetically confined coronal plasma loops observed
on the sun). It is further shown that none of the derivable X-ray
characteristics of RS CVn binaries depend on rotation period, implying
that previous claims of period-activity relationships in RS CVn binaries
were unfounded.

---------------------------------------------------------
Title: Highlights of the Einstein Survey of Cool Stars
Authors: Bookbinder, J.; Golub, L.; Rosner, R.
1986LNP...254...97B Altcode: 1986csss....4...97B
No abstract at ADS

---------------------------------------------------------
Title: A normal incidence X-ray telescope sounding rocket payload
Authors: Golub, L.
1985sao..reptT....G Altcode:
Progress is reported on the following major activities on the X-ray
telescope: (1) complete design of the entire telescope assembly and
fabrication of all front-end components was completed; (2) all rocket
skin sections, including bulkheads, feedthroughs and access door,
were specified; (3) fabrication, curing and delivery of the large
graphite-epoxy telescope tube were completed; (4) an engineering
analysis of the primary mirror vibration test was completed and a
decision made to redesign the mirror attachment system to a kinematic
three-point mount; (5) detail design of the camera control, payload
and housekeeping electronics were completed; and (6) multilayer mirror
plates with 2d spacings of 50 A and 60 A were produced.

---------------------------------------------------------
Title: X-ray spectra and the rotation-activity connection of RS
CVn binaries.
Authors: Majer, P.; Schmitt, J. H. M. M.; Golub, L.; Harnden, F. R.;
Rosner, R.
1985ESASP.239..141M Altcode: 1985cxrs.work..141M
Results from a survey of RS CVn binaries which were observed with the
Imaging Proportional Counter (IPC) on board the Einstein Observatory are
presented. Spectral analyses of the IPC pulse height spectra show that
the coronae of RS CVn binaries always contain hot gas with temperatures
10 million K, similar to active late-type main sequence stars, and
that at least 2 temperature components are necessary to account for
the higher quality IPC spectra (when absorption is unimportant). It
is argued that these bimodal temperature distributions indicate true
distributions of emission measure vs temperature that are continuous
(just as is the case for magnetically-confined coronal plasma loops
observed on the Sun). It is shown that none of the derivable X-ray
characteristics of RS CVn binaries depend on rotation period, implying
that claims of period-activity relationships in RS CVn binaries are
unfounded.

---------------------------------------------------------
Title: Implications of the 1400 MHz Flare Emission from AD Leo for
the Emission Mechanism and Flare Environment
Authors: Holman, G. D.; Bookbinder, J.; Golub, L.
1985ASSL..116...35H Altcode: 1985rst..conf...35H
High brightness temperature spikes have been observed during a radio
flare on the M-dwarf flare star AD Leo (Lang et al., 1983). Their high
brightness temperature (greater than 10 to the 13th K) and circular
polarization indicate that a coherent radiation mechanism must be
responsible for the spike emission. The underlying flare emission,
which is identified with a low polarization, gradual component, was
found not to be spiky to within the 200 ms time resolution of the
observations. This note is concerned primarily with this nonspiky
emission.

---------------------------------------------------------
Title: Einstein X-ray survey of the Pleiades : the dependence of
X-ray emission on stellar age.
Authors: Micela, G.; Sciortino, S.; Serio, S.; Vaiana, G. S.;
Bookbinder, J.; Golub, L.; Harnden, F. R., Jr.; Rosner, R.
1985ApJ...292..172M Altcode:
The data obtained with two pointed observations of 1 deg by 1 deg
fields of the Pleiades region have been analyzed, and the results are
presented. The maximum-likelihood X-ray luminosity functions for the
Pleiades G and K stars in the cluster are derived, and it is shown that,
for the G stars, the Pleiades X-ray luminosity function is significantly
brighter than the corresponding function for Hyades G dwarf stars. This
finding indicates a dependence of X-ray luminosity on stellar age,
which is confirmed by comparison of the same data with median X-ray
luminosities of pre-main sequence and local disk population dwarf G
stars. It is suggested that the significantly larger number of bright
X-ray sources associated with G stars than with K stars, the lack
of detection of M stars, and the relatively rapid rotation of the
Pleiades K stars can be explained in terms of the onset of internal
differential rotation near the convective envelope-radidative core
interface after the spin-up phase during evolution to the main sequence.

---------------------------------------------------------
Title: Solar and stellar coronal plasmas
Authors: Golub, L.
1985sao..reptR....G Altcode:
Progress made in describing and interpreting coronal plasma
processes and the relationship between the solar corona and its
stellar counterparts is reported. Topics covered include: stellar
X-ray emission, HEAO 2 X-ray survey of the Pleiades, closed coronal
structures, X-ray survey of main-sequence stars with shallow convection
zones, implications of the 1400 MHz flare emission, and magnetic
field stochasticity.

---------------------------------------------------------
Title: A normal incidence, high resolution X-ray telescope for solar
coronal observations
Authors: Golub, L.
1985sao..reptQ....G Altcode:
The following major activities were advanced or completed: complete
design of the entire telescope assembly and fabrication of all
front-end components; specification of all rocket skin sections
including bulkheads, feedthroughs and access door; fabrication,
curing, and delivery of the large graphite-epoxy telescope tube;
engineering analysis of the primary mirror vibration test was completed
and a decision made to redesign the mirror attachment to a kinematic
three-point mount; detail design of the camera control, payload and
housekeeping electronics; and multilayer mirror flats with 2d spacings
of 50 A and 60 A.

---------------------------------------------------------
Title: X-Ray Variability in K and M Dwarfs Observed by Einstein
Authors: Ambruster, C.; Sciortino, S.; Golub, L.
1985BAAS...17..598A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An Einstein Observatory X-ray survey of main-sequence stars
with shallow convection zones.
Authors: Schmitt, J. H. M. M.; Golub, L.; Harnden, F. R., Jr.; Maxson,
C. W.; Rosner, R.; Vaiana, G. S.
1985ApJ...290..307S Altcode:
The results of an X-ray survey of bright late A and early F stars
on the main B-V sequence between 0.1 and 0.5 are presented. All the
stars were observed with the Einstein Observatory for a period of at
least 500 seconds. The survey results show significantly larger X-ray
luminosities for the sample binaries than for the single stars. It
is suggested that the difference is due to the presence of multiple
X-ray sources in binaries. It is shown that the X-ray luminosities
for single stars increase rapidly with increasing color, and that
the relation Lx/Lbol is equal to about 10 to the -7th does not hold
for A stars. No correlation was found between X-ray luminosity and
projected equatorial rotation velocity. It is argued on the basis of
the observations that X-ray emission in the sample stars originated
from coronae. The available observational evidence supporting this
view is discussed.

---------------------------------------------------------
Title: Closed coronal structures. VI. Far-ultraviolet and X-ray
emission from active late-type stars and the applicability of coronal
loop models.
Authors: Giampapa, M. S.; Golub, L.; Peres, G.; Serio, S.; Vaiana,
G. S.
1985ApJ...289..203G Altcode:
We present far-ultraviolet line fluxes of prominent transition region
emission lines, as obtained with the International Ultraviolet
Explorer satellite, for a sample of solar-type stars. We combine
the ultraviolet observations with existing soft X-ray measurements
obtained by the Einstein Observatory (HEAO 2). We utilize the resulting
data set and a new coronal loop model numerical code developed at the
Harvard-Smithsonian Center for Astrophysics to perform a preliminary
investigation of the applicability of coronal loop models to solar-type
stars. In a few cases, reasonable agreement between the predictions of
single-component, coronal loop model atmospheres and the observational
data is achieved for a relatively well-defined, plausible range
of values in the pressure-filling factor (p, f) plane. In general,
however, we find that the addition of non- simultaneous ultraviolet
observations to a previously acquired soft X-ray data set does
not provide a sufficient constraint on the range of possible loop
filling factors and pressures for loop model atmospheres that may
be producing the observed X-ray and transition region emissions. We
discuss the origins of the discrepancies between the model results
and the observations within the context of (1) stellar variability,
(2) multiple coronal components, and (3) the presence of relatively
low temperature loops that give rise to far-ultraviolet emission
but not to coronal X-ray emission. We suggest on the basis of the
results presented in this investigation that in order to verify the
applicability of coronal loop models to solar-type stars, simultaneous
far-ultraviolet and moderate spectral resolution X-ray observations
will eventually have to be obtained.

---------------------------------------------------------
Title: On stellar X-ray emission.
Authors: Rosner, R.; Golub, L.; Vaiana, G. S.
1985ARA&A..23..413R Altcode:
Stellar X-ray astronomy represents an entirely new astronomical
discipline which has emerged during the past five years. It lies
at the crossroads of solar physics, stellar physics, and general
astrophysics. The present review is concerned with the main physical
problems which arise in connection with a study of the stellar X-ray
data. A central issue is the extent to which the extrapolation from
solar physics is justified and the definition (if possible) of the
limits to such extrapolation. The observational properties of X-ray
emission from stars are considered along with the solar analogy and the
modeling of X-ray emission from late-type stars, the modeling of X-ray
emission from early-type stars, the physics of stellar X-ray emission,
stellar X-ray emission in the more general astrophysical context,
and future prospects.

---------------------------------------------------------
Title: X-ray emission from solar-type stars: X-ray luminosity function
of late F and G stars.
Authors: Maggio, A.; Bookbinder, J.; Harnden, F. R., Jr.; Golub, L.;
Majer, P.; Rosner, R.; Vaiana, G. S.
1985xra..conf...39M Altcode: 1984xra..conf...39M
The authors present preliminary results from a volume-limited survey
of X-ray emission from late F and G dwarf stars. They have obtained
count rates or upper limits at the locations of catalogued stars
within 25 parsecs for which an observation of the Einstein Imaging
Proportional Counter was available. They have constructed X-ray
luminosity functions for the whole sample and for selected subsamples
of binary and non-binary sources.

---------------------------------------------------------
Title: Theory tested by means of the stars.
Authors: Golub, L.
1985NASCP2358..106G Altcode: 1985onhm.rept..106G
Recent X-ray observations of M dwarfs and Pleiades stars are used to
discuss the relation between surface magnetic fields and the heating
of stellar coronae. The viability of the α-ω dynamo model for stellar
magnetic fields is then examined.

---------------------------------------------------------
Title: Construction of a multilayered X-ray telescope for solar
coronal studies from space.
Authors: Golub, L.; Nystrom, G.; Spiller, E.; Wilczynski, J.
1985SPIE..563..266G Altcode:
The construction and testing of soft x-ray Ritchey-Chretien aplanatic
telescope which is to be flown on a NASA sounding rocket in 1986 for
very high resolution studies of the solar corona are discussed. Goals
include figuring, polishing and measuring the mirror surfaces to
tolerances exceding the 5000 A wavelength diffraction limit while
achieving a superpolished surface finish, and the development of a
structural design to withstand the rigors of the launch. Multilayer
coatings are used to achieve usable reflectivity in the soft X-ray
regime, and the design goal is for spatial resolution of 1/4 sec. Future
applications are discussed.

---------------------------------------------------------
Title: Active late-type stars and the applicability of coronal
loop models.
Authors: Giampapa, M. S.; Golub, L.; Peres, G.; Serio, S.; Vaiana,
G. S.
1984NASCP2349..454G Altcode: 1984fiue.rept..454G; 1984IUE84......454G
Far ultraviolet IUE observations of a sample of solar type stars
were combined with existing soft X-ray measurements obtained by HEAO
B. The resulting data set was utilized and a new coronal loop model
numerical code was developed to perform a preliminary investigation of
the applicability of coronal loop models to solar-type stars. Reasonable
agreement was found to exist between the predictions of single-component
coronal loop model atmospheres. It was demonstrated that semi-empirical,
coronal loop models can be applied to account for observed stellar
transition region and coronal emission. This result is corroborative
evidence for the presence of magnetic field structures analogous to
solar coronal loops on the surfaces of solar-type stars. It is suggested
that stellar transition region emission arises predominantly from the
base of quiescent coronal loop configurations.

---------------------------------------------------------
Title: A normal incidence, high resolution X-ray telescope for solar
coronal observations
Authors: Golub, L.
1984sao..reptT....G Altcode:
Efforts directed toward the completion of an X-ray telescope assembly
design, the procurement of major components, and the coordination of
optical fabrication and X-ray multilayer testing are reported.

---------------------------------------------------------
Title: An X-ray Survey of Solar-Type Stars
Authors: Bookbinder, J. A.; Majer, P.; Golub, L.; Rosner, R.
1984BAAS...16Q.940B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Stellar chromospheres and coronae in the Ursa Major cluster
stars.
Authors: Walter, F. M.; Linsky, J. L.; Simon, T.; Golub, L.; Vaiana,
G. S.
1984ApJ...281..815W Altcode:
IUE spectra of 18 proposed members of the Ursa Major Cluster and
Einstein X-ray images of 11 of these stars are discussed. Thirteen
stars, six in the nucleus and seven in the extended comoving stream,
are probably true members of the UMa Cluster in that their bright
ultraviolet and X-ray surface fluxes indicate youth. Four stars, one in
the nucleus and three in the stream, exhibit weak ultraviolet and/or
X-ray emission suggesting that they are old field stars that have
the same space motion as the UMa Cluster. The X-ray surface fluxes of
the UMa Cluster stars appear to be brighter than those of the Hyades
Cluster stars, consistent with their relative ages. It is argued that
chromospheres and transition regions could be present in dwarf stars
hotter than B-V of about 0.30, but are unobservable in IUE spectra
due to the rapid increase in photospheric flux in hotter stars.

---------------------------------------------------------
Title: A normal incidence, high resolution X-ray telescope for solar
coronal observations
Authors: Golub, L.
1984sao..reptQ....G Altcode:
A Normal Incidence high resolution X-ray Telescope is reported. The
design of a telescope assembly which, after fabrication, will be
integrated with the mirror fabrication process is described. The
assembly is engineered to fit into the Black Brant rocket skin to
survive sounding rocket launch conditions. A flight ready camera is
modified and tested.

---------------------------------------------------------
Title: Erratum - Einstein Observations of X-Ray Emission from A-Stars
Authors: Golub, L.; Harnden, F. R.; Maxson, C. W.; Rosner, R.; Vaiana,
G. S.; Cash, W., Jr.; Snow, T. P., Jr.
1984ApJ...278..456G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray Spectra of RS CVn Binaries
Authors: Majer, P.; Schmitt, J. H. M.; Golub, L.; Harnden, F. R.,
Jr.; Rosner, R.
1984BAAS...16..514M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An X-ray Survey of Late-Type Dwarf Stars
Authors: Bookbinder, J. A.; Schmitt, J. H. M.; Golub, L.; Rosner, R.
1984BAAS...16..515B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Measurements of Rotational Velocities of F and G Stars
Authors: Noci, Giancarlo; Ortolani, Sergio; Rossi, Pierluigi;
Golub, Leon
1984LNP...193..105N Altcode: 1984csss....3..105N
No abstract at ADS

---------------------------------------------------------
Title: Evolution of solar magnetic flux.
Authors: Boris, J. P.; DeVore, C. R.; Golub, L.; Howard, R. F.; Low,
B. C.; Sheeley, N. R., Jr.; Simon, G. W.; Tsinganos, K. C.
1984NASRP1120....3B Altcode:
Contents: Introduction. Appearance of magnetic flux: models for flux
emergence, unexplained observations. Dynamics of surface magnetic
flux: magnetic flux transport, magnetic flux structure. Disappearance
of magnetic flux: theoretical considerations, observations of flux
disappearance. Summary.

---------------------------------------------------------
Title: X-Ray Survey of the Pleiades - Dependence of X-Ray Luminosity
on Stellar Age
Authors: Micela, G.; Sciortino, S.; Serio, S.; Vaiana, G. S.; Golub,
L.; Harnden, F. R.; Rosner, R.
1984IAUS..105..101M Altcode:
The authors report preliminary results from an Einstein X-ray survey
of the Pleiades. They have analysed a 1°×1° exposure centered over
one of the more luminous stars of the cluster (20 Tau, [B7 III]). This
field contains ≡62 cluster members out of a total of ≡270 stars with
magnitude lower than 14m. (Hertzsprung, 1947). The authors
have detected 17 distinct X-ray sources; 16 sources are identified
with cluster stars within a distance less than 1arcmin.

---------------------------------------------------------
Title: Solar coronal studies using normal-incidence X-ray optics
Authors: Golub, L.
1984AdSpR...4h..75G Altcode: 1984AdSpR...4...75G
We describe the progress which has been made in constructing a new type
of X-ray telescope, which operates at normal incidence in the soft X-ray
region by the use of multilayer coatings. The principles involved in
state-of-the-art multilayer technology and some recent high-resolution
imaging results are discussed. A rocket payload incorporating a
multilayer X-ray mirror is presently being constructed. It is of
Ritchey-Chretien design and the expected spatial resolution is 1/4
arcsec. The scientific program for solar coronal studies and future
instrumental developments are also discussed.

---------------------------------------------------------
Title: X-Ray Variable Stars in the Pleiades
Authors: Sciortino, S.; Micela, G.; Serio, S.; Vaiana, G. S.; Golub,
L.; Harnden, F. R., Jr.; Rosner, R.
1983IBVS.2449....1S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray observations of the solar corona.
Authors: Golub, L.
1983NASCP2280...45G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray Emission from A and F Stars - What Do We Learn About
Convection and Dynamos?
Authors: Schmitt, J. H. M.; Golub, L.; Harnden, F. R., Jr.; Maxson,
C. W.; Rosner, R.
1983BAAS...15Q.948S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Bright, rapid, highly circularly polarized radio spikes from
the M dwarf AD Leonis.
Authors: Lang, K. R.; Bookbinder, J.; Golub, L.; Davis, M. M.
1983ApJ...272L..15L Altcode:
A rapid sequence of highly polarized spikes was observed during the
gradual rise of a longer lasting event in an Arecibo Observatory
study of a radio burst at 1400 MHz from the main sequence radio star
AD Leo. The maximum flux density of the spikes was 130 mJy, and they
had rise times of less than about 200 msec. The rise times provide an
upper limit to the linear size of the emitter of 6 billion cm, and an
area of less than 0.03 of the star's surface area is inferred, for a
spike brightness temperature of more than about 10 to the 13th K. The
high brightness temperatures and high degrees of circular polarization
are explained in terms of electron-cyclotron maser emission at the
second harmonic of the gyrofrequency, in longitudinal magnetic fields
of about 250 G.

---------------------------------------------------------
Title: Einstein observations of X-ray emission from A stars.
Authors: Golub, L.; Harnden, F. R., Jr.; Maxson, C. W.; Rosner, R.;
Vaiana, G. S.; Cash, W., Jr.; Snow, T. P., Jr.
1983ApJ...271..264G Altcode:
Results are reported from the combined CfA Stellar Survey of selected
bright A stars and an Einstein Guest Observer program for Ap and Am
stars. In an initial report of results from the CfA Stellar Surveys
by Vaiana et al. (1981) it was noted that the spread in observed X-ray
luminosities among the few A stars observed was quite large. The reasons
for this large spread was studied by Pallavicini et al. (1981). It was
found that the X-ray emission from normal stars is related very strongly
to bolometric luminosity for early-type stars and to rotation rate
for late-type stars. However, an exception to this rule has been the
apparently anomalous behavior of A star X-ray emission, for which the
large spread in luminosity showed no apparent correlation with either
bolometric luminosity or stellar rotation rate. In the present study,
it is shown that the level of emission from normal A stars agrees with
the correlation observed for O and B stars.

---------------------------------------------------------
Title: The magnetic field on the RS Canum Venaticorum star lambda
Andromeda.
Authors: Giampapa, M. S.; Golub, L.; Worden, S. P.
1983ApJ...268L.121G Altcode:
A program to detect and measure magnetic flux on the surfaces of
late-type stars is discussed. A technique is adopted to deconvolve
magnetically insensitive lines from similar, magnetically sensitive
lines to infer the degree of Zeeman splitting in the latter lines. These
measurements yield values for the magnetic field strength and filling
factor (flux). To illustrate the approach, observations of the RS
CVn star Lambda And are presented. At the epoch of observation, 1981
April 26, a field strength of 1290 + or - 320 gauss covering 48 + or -
7 percent of this star's surface is found. This measurement compares
with an estimate of coronal magnetic flux in the cooler component of
the stellar corona of 1110 gauss with a coronal volume filling factor
of 75 percent, based on X-ray data for Lambda And.

---------------------------------------------------------
Title: Bright, rapid, highly polarized radio spikes from the M dwarf
AD Leo
Authors: Lang, K. R.; Bookbinder, J.; Golub, L.
1983tuft.reptS....L Altcode:
We have observed a radio burst from the main sequence (dM4.5e) star AD
Leo at 1400 MHz from 0536 to 0556 UT on 1983 February 1 at the Arecibo
Observatory. A rapid sequence of highly polarized spikes was observed
during the gradual rise of a longer lasting, unpolarized event. The
maximum flux density of the spikes was S(max) = 130 mJy, and they had
rise times less than or approx. 200 ms. The spikes were all 100% left
hand circularly polarized with an instrumental uncertainty of 5%. The
rise times provide an upper limit to the linear size L less than or
approx. 6 x 10 to the 9th power cm for the emitter. Provided that the
source is symmetric, it has an area that is less than three hundredths
of the star's surface area. In this case, the lower limit to the
brightness temperature of the spikes is TB greater than or approx. 10 to
the 13th power K. The high brightness temperatures and high degrees of
circular polarization are explained in terms of electron-cyclotron maser
emission at the second harmonic of the gyrofrequency in longitudinal
magnetic fields of strength Hl approx. 250 gauss. The unpolarized
gradual component did not exhibit any rapid fluctuations, and it was
entirely analogous to the thermal emission of solar bursts.

---------------------------------------------------------
Title: Coordinated Einstein and IUE observations of a disparitions
brusques type flare event and quiescent emission from Proxima
Centauri.
Authors: Haisch, B. M.; Linsky, J. L.; Bornmann, P. L.; Stencel,
R. E.; Antiochos, S. K.; Golub, L.; Vaiana, G. S.
1983ApJ...267..280H Altcode:
The Einstein Imaging Particle Counter observed a major X-ray flare
in its entirety during a 5-hr period of simultaneous observations,
with the IUE, of the dM5e flare star Proxima Centauri in August,
1980. The detailed X-ray light curve, temperature determinations
during various intervals, and UV line fluxes obtained before, during,
and after the flare indirectly indicate a 'two-ribbon flare' prominence
eruption. The calculated ratio of coronal to bolometric luminosity for
the event is about 100 times the solar ratio. The Proxima Cen corona
is analyzed in the context of static loop models, in light of which
it is concluded that less than 6% of the stellar surface seems to be
covered by X-ray emitting active regions.

---------------------------------------------------------
Title: An X-ray Survey of Main Sequence Stars with Shallow Convection
Zones
Authors: Schmitt, J. H. M.; Golub, L.; Harnden, F. R., Jr.; Maxson,
C. W.; Vaiana, G. S.
1983BAAS...15..673S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-rays from stars.
Authors: Golub, L.
1983Ast....11...66G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Quiescent coronae of active chromosphere stars
Authors: Golub, L.
1983ASSL..102...83G Altcode: 1983ards.proc...83G; 1983IAUCo..71...83G
Quiescient X-ray emission from M dwarfs and the changes in quiescent
levels on time scales from hours to about one year are discussed based
on Einstein Observatory data. The coronal temperatures for many of
these stars are determined; they are generally hotter than the solar
corona and some of the more active dM stars have coronal temperatures of
about 10 million K. Arguments in support of the hypothesis that M-dwarf
coronae are magnetically dominated are presented. The usefulness of
loop model atmosphere calculations in elucidating the coronal heating
mechanism and the ways in which observations may be used to test
competing theories are examined. The X-ray measuremnts can be used
to predict magnetic field strengths on these stars, with testable
implications.

---------------------------------------------------------
Title: Empirical scaling laws for coronal heating
Authors: Golub, L.
1983IAUS..102..345G Altcode:
The origins and uses of scaling laws in studies of stellar outer
atmospheres are reviewed with particular emphasis on the properties
of coronal loops. Some evidence is presented for a fundamental
structuring of the solar corona and the thermodynamics of scaling
laws are discussed. It is found that magnetic field-related scaling
laws can be obtained by relating coronal pressure, temperature, and
magnetic field strength. Available data validate this method. Some
parameters of the theory, however, must be treated as adjustable,
and it is considered necessary to examine data from other stars in
order to determine the validity of the parameters. Using detailed
observational data, the applicability of single loop models is examined.

---------------------------------------------------------
Title: The Temperature-Luminosity Dependence of Stellar X-ray Sources
Authors: Vaiana, G. S.; Serio, S.; Sciortino, S.; Golub, L.; Maxson,
C.; Rosner, R.
1982BAAS...14..945V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray Sources in the Pleiades
Authors: Micela, G.; Serio, S.; Vaiana, G. S.; Golub, L.
1982BAAS...14..891M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A Normal Incidence X-ray Telescope for Solar Studies
Authors: Golub, L.; Rosner, R.; Vaiana, G. S.; Zombeck, M. V.; Spiller,
E.; Wilczynski, J.
1982BAAS...14..976G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-ray Variability of Late-type Stars
Authors: Maggio, A.; Serio, S.; Vaiana, G. S.; Golub, L.
1982BAAS...14R.945M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Active region coronal evolution
Authors: Golub, L.; Noci, G.; Poletto, G.; Vaiana, G. S.
1982ApJ...259..359G Altcode:
Scaling relations between coronal base pressure and longitudinal
photospheric magnetic field strength are tested for the case of a
single active region observed for five solar rotations from Skylab. The
evolution of measureable quantities, such as coronal thermal energy
content, total longitudinal photospheric magnetic flux, region scale
size, and peak energy density, is traced throughout the five rotations
observed. The theoretically derived scaling law of Golub et al. (1980)
is found to provide an acceptable fit to the data throughout the entire
evolutionary history of the region from an age of about 3 days to
the fully evolved state in which the mature active region merges into
the general large-scale structure of the quiet corona. An alternative
scaling law obtained by including the results of Galeev et al. (1981),
however, is found to provide a somewhat better fit to the data. The
study is seen as providing additional justification for the belief
that magnetic field-related heating is the operative mechanism in the
solar corona.

---------------------------------------------------------
Title: A magnitude limited stellar X-ray survey and the F star X-ray
luminosity function.
Authors: Topka, K.; Golub, L.; Gorenstein, P.; Harnden, F. R., Jr.;
Vaiana, G. S.; Avni, Y.; Rosner, R.
1982ApJ...259..677T Altcode:
An X-ray survey has been conducted of stars brighter than visual
magnitude 8.5 that have serendipitously fallen into the fields of view
of the Imaging Proportional Counter of the Einstein Observatory. The
survey includes 227 separate 1 x 1 deg fields, containing 274 stars
with a visual magnitude of no more than 8.5 and covering a wide range
of spectral types and luminosity classes. X-ray emission was detected
from 33 stars, and upper limits have been determined for the remainder
of the sample. F type stars dominate the detected sample, and most of
these are shown to be dwarfs. An X-ray luminosity function for dF stars
has been deduced, and reveals that the average 0.2-4.0 keV luminosity
of these stars is around 10 to the 29th erg/sec. Constraints have been
placed on the high luminosity tails and medians of the X-ray luminosity
functions for other types of stars.

---------------------------------------------------------
Title: STCOEX: The stellar X-ray coronal Explorer.
Authors: Vaiana, G. S.; Golub, L.; Maxson, C. W.; Rosner, R.; Zombeck,
M. V.
1982SAOSR.392B.253V Altcode: 1982csss....2..253V
No abstract at ADS

---------------------------------------------------------
Title: A heating mechanism for the chromospheres of M dwarf stars.
Authors: Giampapa, M. S.; Golub, L.; Rosner, R.; Vaiana, G. S.;
Linsky, J. L.; Worden, S. P.
1982SAOSR.392A..73G Altcode: 1982csss....2...73G
The atmospheric structure of the dwarf M-stars which is especially
important to the general field of stellar chromospheres and coronae
was investigated. The M-dwarf stars constitute a class of objects
for which the discrepancy between the predictions of the acoustic
wave chromospheric/coronal heating hypothesis and the observations is
most vivid. It is assumed that they represent a class of stars where
alternative atmospheric heating mechanisms, presumably magnetically
related, are most clearly manifested. Ascertainment of the validity
of a hypothesis to account for the origin of the chromospheric and
transition region line emission in M-dwarf stars is proposed.

---------------------------------------------------------
Title: Second Cambridge workshop on cool stars, stellar systems,
and the sun. Vol. 1. Proceedings of a workshop held at the
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, October
21 - 23, 1981.
Authors: Giampapa, M. S.; Golub, L.
1982SAOSR.392A....G Altcode: 1982csss....2A....G
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric emission, stellar rotation and X-ray coronae.
Authors: Pallavicini, R.; Golub, L.; Rosner, R.; Vaiana, G.
1982SAOSR.392B..77P Altcode: 1982csss....2...77P
No abstract at ADS

---------------------------------------------------------
Title: Einstein detection of X-rays from the alf CEN system.
Authors: Golub, L.; Harnden, F. R., Jr.; Pallavicini, R.; Rosner,
R.; Vaiana, G. S.
1982ApJ...253..242G Altcode:
Detection of quiescent X-ray emission from the stellar components
of the Alpha Cen system: Alpha Cen A (G2 V) and Alpha Cen B (K1 V)
is reported. Contrary to previous theoretical expectations, both
stars are found to be X-ray emitters and at about the same level:
Lx = 1.2 x 10 to the 27th and 2.8 x 10 to the 27th ergs/s
for A and B, respectively; the sum of these values is in agreement
with the emission level previously reported for Alpha Cen by Nugent and
Garmire (1978). Comparison with previous chromospheric and transition
region measurements suggests that Alpha Cen A and B may have changed
in relative strength in recent years. The coronal temperature of the
combined Cen AB source, which is dominated (approximately 2/3 of the
total) by the K star is (2.1 + or - 0.4) x 10 to the 6th K, similar to
that of the average solar corona; it is noted that this value is not
consistent with the estimate of 5 x 10 to the 5th K quoted by Nugent
and Garmire.

---------------------------------------------------------
Title: Preface
Authors: Giampapa, Mark; Golub, Leon
1982SAOSR.392D...9G Altcode: 1982csss....2D...9G
No abstract at ADS

---------------------------------------------------------
Title: Solar activity - the sun as an X-ray star.
Authors: Golub, L.
1982SAOSR.392A..39G Altcode: 1982csss....2...39G
The existence and constant activity of the Sun's outer atmosphere are
thought to be due to the continual emergence of magnetic fields from
the Solar interior and the stressing of these fields at or near the
surface layers of the Sun. The structure and activity of the corona are
thus symptomatic of the underlying magnetic dynamo and the existence of
an outer turbulent convective zone on the Sun. A sufficient condition
for the existence of coronal activity on other stars would be the
existence of a magnetic dynamo and an outer convective zone. The
theoretical relationship between magnetic fields and coronal activity
can be tested by Solar observations, for which the individual loop
structures can be resolved. A number of parameters however, which
enter into the alternative theoretical formulations remain fixed in all
Solar observations. To determine whether these are truly parameters of
the theory observations need to be extended to nearby stars on which
suitable conditions may occur.

---------------------------------------------------------
Title: Stellar contribution to the diffuse soft X-ray background.
Authors: Bookbinder, J.; Avni, Y.; Golub, L.; Rosner, R.; Vaiana, G.
1982SAOSR.392A.201B Altcode: 1982csss....2..201B
One of the results of the EINSTEIN/C.f.A. X-ray stellar survey was
a determination of the contribution of the disk stellar population
to the galactic component of the diffuse soft (0.28 - 1.0 keV)
X-ray background. This analysis employed both binned and unbinned
nonparametric statistical methods that have been developed by Avni, et
al. (1980). These methods permitted the use of the information contained
in both the 22 detections and 4 upper bounds on the luminosities of
26 dM stars in order to derive their luminosity function. Luminosity
functions for earlier stellar types are not yet developed. For these
earlier stellar types, the median luminosities as determined by Vaiana,
et al., are used (1981), which underestimates their contribution to
the background. We find that it is the M dwarfs that dominate the disk
population stellar contribution to this background. To calculate the
contribution of the stellar sources to the background, simple models
both for the spatial distribution of the stars and for the properties
of the intervening interstellar medium are used. A model is chosen
in which all stellar classes have the same functional form for their
spatial distribution: an exponentially decreasing distribution above
the galactic equatorial plane, and a uniform distribution within the
galactic plane for a region of several kiloparsecs centered on the Sun.

---------------------------------------------------------
Title: Coordinated X-ray, optical and radio observations of flaring
activityon YZ Canis Minoris.
Authors: Kahler, S.; Golub, L.; Harnden, F. R.; Liller, W.; Seward,
F.; Vaiana, G.; Lovell, B.; Davis, R. J.; Spencer, R. E.; Whitehouse,
D. R.; Feldman, P. A.; Viner, M. R.; Leslie, B.; Kahn, S. M.; Mason,
K. O.; Davis, M. M.; Crannell, C. J.; Hobbs, R. W.; Schneeberger,
T. J.; Worden, S. P.; Schommer, R. A.; Vogt, S. S.; Pettersen, B. R.;
Coleman, G. D.; Karpen, J. T.; Giampapa, M. S.; Hege, E. K.; Pazzani,
V.; Rodono, M.; Romeo, G.; Chugainov, P. F.
1982ApJ...252..239K Altcode:
The YZ Canis Minoris (Gliese 285), a late-type dwarf star with
Balmer emission (dM4.5e), is a member of the UV Ceti class of flare
stars. Obtaining good X-ray observations of a dMe star flare is
important not only for understanding the physics of flares but also for
testing current ideas regarding the similarity between stellar and solar
flares. The Einstein X-ray Observatory has made it possible to conduct
X-ray observations of dMe stars with unprecedented sensitivity. A
description is presented of the results of a program of ground-based
optical and radio observations of YZ CMi coordinated with those of
the Einstein Observatory. The observations were carried out as part
of a coordinated program on October 25, 26, and 27, 1979, when YZ CMi
was on the dawn side of the earth. Comprehensive observational data
were obtained of an event detected in all three wavelength regions on
October 25, 1979.

---------------------------------------------------------
Title: What heats the solar corona?
Authors: Golub, L.
1982Ast....10i..74G Altcode:
No abstract at ADS

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Title: Solar and late-type dwarfs
Authors: Golub, L.
1982AdSpR...2i.215G Altcode: 1982AdSpR...2..215G
The Einstein Observatory and the IUE satellite have provided
the observational basis for a major restructuring in theories of
coronal formation for late-type stars. For the first time, coronal
and transition region emission from a large sample of low mass
(1 Mo) dwarf stars has been directly observed, with
the unexpected result that essentially all such stars are x-ray
emitters. The Sun, which was previously assumed to be typical, is
now known to be at the low end of the x-ray luminosity function for
solar-type stars. K- and M-dwarfs are observed to have nearly the
same luminosity distributions as G-dwarfs and all of these spectral
types have a large spread in x-ray luminosity. Observationally,
there is a strong correlation between the strength of coronal emission
in stars with outer convective zones and the rotation rates of these
stars. At the present time we have only the beginnings of a satisfactory
theoretical explanation for this correlation; although we are beginning
to understand the connection between coronal emission strength and
the magnetic field, we do not yet understand the stellar dynamo which
generates the magnetic field. Studies of the coronal emission of stars
may lead to a better understanding of stellar dynamos.

---------------------------------------------------------
Title: Solar corona at high resolution
Authors: Golub, L.; Rosner, R.; Zombeck, M. V. Z.; Vaiana, G. S.
1982SPIE..316..149G Altcode:
The earth's surface is shielded from solar X rays almost completely by
the atmosphere. It is, therefore, necessary to place X-ray detectors
on rockets or orbiting satellites. Solar rays were detected for the
first time in the late 1940's, using V-2 rockets. In 1960, the first
true X-ray images of the sun were obtained with the aid of a simple
pinhole camera. The spatial resolution of the X-ray images could be
considerably improved by making use of reflective optics, operating at
grazing incidence. Aspects of X-ray mirror developments are discussed
along with the results obtained in coronal studies utilizing the new
devices for the observation of solar X-ray emission. It is pointed
out that the major achievements of the Skylab missions were due
primarily to the unique opportunity to obtain data over an extended
period of time. Attention is given to normal incidence X-ray optics,
achievements possible by making use of high spatial resolution optics,
and details of improved mirror design.

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Title: The cool Half of the H-R diagram in soft X-rays.
Authors: Ayres, T. R.; Linsky, J. L.; Vaiana, G. S.; Golub, L.;
Rosner, R.
1981ApJ...250..293A Altcode:
The results of an Einstein Observatory program to map the occurrence
of hot coronae (T greater than 1 million K) in the cool half of the
Hertzsprung-Russell diagram are reported. F-M dwarfs, and late F
through early K star giants characterized by 10,000 K chromospheric
and 20,000-200,000 K FUV emission lines were studied in one region,
while a second region study included red giants later than K2 III and
supergiants later than G5 Ib with weaker chromospheric emission and
no high temperature species. Program goals comprised determination of
the C IV division as seen in soft X-rays, and identification of stellar
parameters which distinguish strong from weak coronal X-ray sources. A
summary of target stars, X-ray fluxes, and UV emission profiles
is provided, and coronal emissions, comparisons of C IV and wind
boundaries, hybrid-spectrum supergiants, the energy balance of stellar
outer atmospheres, stellar rotation and coronae, and evolutionary
considerations are discussed, along with lines of future research.

---------------------------------------------------------
Title: The stellar contribution to the galactic soft X-ray background
Authors: Rosner, R.; Avni, Y.; Bookbinder, J.; Giacconi, R.; Golub,
L.; Harnden, F. R., Jr.; Maxson, C. W.; Topka, K.; Vaiana, G. S.
1981ApJ...249L...5R Altcode:
Log N-log S relations for stars are constructed based on median
X-ray luminosities for dF, dG, and dK stars previously reported for
the Einstein Observatory/Center for Astrophysics stellar survey and
on a detailed X-ray luminosity function derived here for dM stars,
and the stellar contribution to the diffuse soft X-ray background is
investigated. The principal results are that stars provide approximately
20% of the soft X-ray background in the 0.28-1.0 keV passband and
therefore contribute significantly to the soft X-ray background in this
energy range (with dM stars constituting the dominant contributing
class), and that the stellar contribution to the diffuse X-ray
background in the 0.15-0.28 keV passband is less than approximately 3%.

---------------------------------------------------------
Title: Relations among stellar X-ray emission observed from Einstein,
stellar rotation and bolometric luminosity.
Authors: Pallavicini, R.; Golub, L.; Rosner, R.; Vaiana, G. S.; Ayres,
T.; Linsky, J. L.
1981ApJ...248..279P Altcode:
The correlation between observed stellar X-ray luminosities, bolometric
luminosities, and projected rotational velocities for stars of various
spectral types and luminosity classes are determined. Early type
stars (O3 to A5) have X-ray luminosities independent of rotational
velocities, and correlating with bolometric luminosities. Late type
stars of spectral type G to M have luminosities well correlated to
equatorial rotational velocities, and are independent of luminosity
class. The dependence of late type stars is found to be equivalent
to a relation between the X-ray surface flux and the stellar angular
velocity. F stars are intermediate with X-ray luminosities higher
than would be predicted on the basis of the early type star relation,
although lower than expected from the late type velocity dependence. The
location of RS CVn stars as a class is also discussed, and it is found
that the heating of late type stellar coronas does not result from
direct conversion of ratational energy.

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Title: Closed coronal structures. III - Comparison of static models
with X-ray, EUV, and radio observations
Authors: Pallavicini, R.; Peres, G.; Serio, S.; Vaiana, G. S.; Golub,
L.; Rosner, R.
1981ApJ...247..692P Altcode:
Numerical models of static coronal loops in energy balance are compared
with high spatial resolution observations of extreme ultraviolet lines,
broad-band X-ray emission, and interferometric observations at 2.8 cm
of a solar active region. Difficulties of using scaling laws to test
static models of coronal loops are reviewed. The theoretical model
used for the comparison is summarized; the detailed X-ray, EUV, and
microwave observations of the selected active region are presented;
and the comparison of the model with the observations is performed. It
is shown that simple static models with conductive flux vanishing at the
loop base reproduce satisfactorily the observed properties in the upper
portion of loop structures from compact, high-pressure loops in the
core of the region to more extended, fainter loops and to large-scale
loops interconnecting different active regions. Effects of changing
loop parameters are investigated, and it is argued, that in contrast
to the present approach, scaling laws cannot be used to discriminate
between different static energy balance models. Some discrepancy is
found between model predictions and observations for the lower sections
of loop structures. Possible causes of the discrepancy are discussed.

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Title: Results from an extensive Einstein stellar survey.
Authors: Vaiana, G. S.; Cassinelli, J. P.; Fabbiano, G.; Giacconi,
R.; Golub, L.; Gorenstein, P.; Haisch, B. M.; Harnden, F. R., Jr.;
Johnson, H. M.; Linsky, J. L.; Maxson, C. W.; Mewe, R.; Rosner, R.;
Seward, F.; Topka, K.; Zwaan, C.
1981ApJ...245..163V Altcode:
The preliminary results of the Einstein Observatory stellar X-ray survey
are presented. To date, 143 soft X-ray sources have been identified with
stellar counterparts, leaving no doubt that stars in general constitute
a pervasive class of low-luminosity galactic X-ray sources. Stars along
the entire main sequence, of all luminosity classes, pre-main sequence
stars as well as very evolved stars have been detected. Early type
OB stars have X-ray luminosities in the range 10 to the 31st to 10 to
the 34th ergs/s; late type stars show a somewhat lower range of X-ray
emission levels, from 10 to the 26th to 10 to the 31st ergs/s. Late type
main-sequence stars show little dependence of X-ray emission levels upon
stellar effective temperature; similarly, the observations suggest weak,
if any, dependence of X-ray luminosity upon effective gravity. Instead,
the data show a broad range of emission levels (about three orders of
magnitude) throughout the main sequence later than F0.

---------------------------------------------------------
Title: Solar corona at high resolution.
Authors: Golub, L.; Rosner, R.; Vaiana, G. S.; Zombeck, M. V.
1981SPIE..316..149G Altcode:
No abstract at ADS

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Title: Solar magnetic fields - The generation of emerging flux
Authors: Golub, L.; Rosner, R.; Vaiana, G. S.; Weiss, N. O.
1981ApJ...243..309G Altcode:
X-ray observations have provided information about magnetic fields on
the sun, and the implications of these observations are discussed. The
pattern of small-scale flux emergence is quite different from that of
active regions. It is inferred that the small-scale fields originate
fairly high in the convective zone, while the fields in active regions
have a deeper origin. The small-scale turbulent fields are only loosely
related to the fields that define the normal solar cycle. The way in
which dynamo models must be modified in the light of these results
is indicated.

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Title: Closed coronal structures. II - Generalized hydrostatic model
Authors: Serio, S.; Peres, G.; Vaiana, G. S.; Golub, L.; Rosner, R.
1981ApJ...243..288S Altcode:
Numerical computations of stationary solar coronal loop atmospheres
are used to extend earlier analytical work. Two classes of loops are
examined, namely symmetric loops with a temperature maximum at the
top but now having a length greater than the pressure scale height and
loops which have a local temperature minimum at the top. For the first
class, new scaling laws are found which relate the base pressure and
loop length to the base heating, the heating deposition scale height,
and the pressure scale height. It is found that loops for which the
length is greater than about two to three times the pressure scale
height do not have stable solutions unless they have a temperature
minimum at the top. Computed models with a temperature inversion at the
top are permitted in a wider range of heating deposition scale height
values than are loops with a temperature maximum at the top. These
results are discussed in relation to observations showing a dependence
of prominence formation and stability on the state of evolution of
magnetic structures, and a general scenario is suggested for the
understanding of loop evolution from emergence in active regions
through the large-scale structure phase to opening in coronal holes.

---------------------------------------------------------
Title: Solar magnetism: a new look.
Authors: Golub, L.
1981Ast.....9c..66G Altcode:
No abstract at ADS

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Title: The Cool Half of the HR Diagram in Soft X-Rays
Authors: Ayres, T. R.; Linsky, J. L.; Vaiana, G. S.; Golub, L.;
Rosner, R.
1980BAAS...12..870A Altcode:
No abstract at ADS

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Title: Hα Activity in X-Ray Bright Points and the Origin of Spicules
Authors: Moore, R. L.; Golub, L.
1980BAAS...12..817M Altcode:
No abstract at ADS

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Title: Einstein Observations of A-Stars
Authors: Golub, L.; Vaiana, G. S.; Snow, T. P.; Cash, W. C.
1980BAAS...12..872G Altcode:
No abstract at ADS

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Title: Transition Region and Corona in Solar Active Regions:
Observations and Numerical Modeling
Authors: Golub, L.; Pallavicini, R.; Peres, G.; Rosner, R.; Serio,
S.; Vaiana, G. S.
1980BAAS...12..908G Altcode:
No abstract at ADS

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Title: X-ray Bright Points and the Solar Cycle
Authors: Golub, L.
1980RSPTA.297..595G Altcode: 1980RSLPT.297..595G
Soft X-ray filtergrams show the presence on the Sun of large numbers
of small, closed regions of coronal emission. These features, called
'X-ray bright points' correspond to small, short-lived regions of
emerging magnetic flux. As a function of size or lifetime they form
a broad spectrum of activity which is continuous with the active
regions. The shape of the Sun's activity spectrum is such that most of
all magnetic flux emerging at the surface comes in the form of bright
points. From this viewpoint, active regions may be viewed as the long
lifetime tail end of the bright point spectrum. Examination of soft
X-ray data obtained from 1970 to 1978 shows that the number of bright
points appears to be anticorrelated with traditional activity indices
such as sunspot number; the anticorrelation persists after corrections
are made for obscuration by active regions. Comparison of X-ray data
with KPNO magnetograms shows that to within a factor of 2, the average
total amount of magnetic flux emerging over the full Sun is constant
through the entire period of observation. The solar cycle therefore
appears to be more an oscillation in the wavenumber distribution of
emerging flux than of the total quantity of magnetic flux produced.

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Title: Magnetic fields and coronal heating
Authors: Golub, L.; Maxson, C.; Rosner, R.; Vaiana, G. S.; Serio, S.
1980ApJ...238..343G Altcode:
General considerations concerning the scaling properties of
magnetic-field-related coronal heating mechanisms are used to build
a two-parameter model for the heating of closed coronal regions. The
model predicts the way in which coronal temperature and electron density
are related to photospheric magnetic field strength and the size of the
region, using the additional constraint provided by the scaling law of
Rosner, Tucker, and Vaiana. The model duplicates the observed scaling
of total thermal energy content with total longitudinal flux; it also
predicts a relation between the coronal energy density (or pressure)
and the longitudinal field strength modified by the region scale size.

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Title: Coordinated X-Ray, Optical, and Radio Observations of Flares
from the dMe Star YZ Canis Minoris
Authors: Kahler, S. W.; Golub, L.; Harnden, F. R.; Seward, F. D.;
Vaiana, G. S.
1980BAAS...12..526K Altcode:
No abstract at ADS

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Title: Association of flaring X-ray bright points with type III bursts
Authors: Kundu, M. R.; Gergely, T. E.; Golub, L.
1980ApJ...236L..87K Altcode:
Using the swept-frequency radio observations obtained at the Clark
Lake Radio Observatory and the X-ray photographs taken by the S-054
experiment aboard Skylab, a search has been made for type III bursts
associated with X-ray bright point (XBP) flares. Using temporal as
well as spatial criteria for the association, four such events are
found over a period of 43 days. The time period was selected in such
a way that the level of flare and radio activity was low in order to
minimize the chance coincidences. The detection of type III bursts from
the flaring XBPs is of great interest, since it identifies them with the
flare process, of which XBP flares are thought to be the simplest form.

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Title: X-Ray Bright Points and the Solar Cycle
Authors: Golub, L.; Vaiana, G. S.
1980NASCP2098...75G Altcode: 1980sscs.nasa...75G
The shape of the Sun's activity spectrum is such that the majority of
all magnetic flux emerging at the surface comes in the form of bright
points, i.e., regions living less than two days. Examination of soft
X-ray data obtained from 1970 to 1978 shows that the number of bright
points appears to be anticorrelated with traditional activity indices,
such as sunspot number; the anticorrelation persists after corrections
are made for obscuration by active regions. Comparison of X-ray data
with KPNO magnetograms shows that to within a factor of two, the average
total amount of magnetic flux emerging over the full Sun is constant
through the entire period of observation. The Solar cycle therefore
appears to be more an oscillation in the wavenumber distribution of
emerging flux than of the total quantity of magnetic flux produced.

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Title: Rotational Variations in the Nonflaring Optical and X-Ray
Fluxes of Yz-Canis
Authors: Pettersen, B. R.; Kahler, S.; Golub, L.; Vaiana, G. S.
1980SAOSR.389..113P Altcode: 1980csss....1..113P
No abstract at ADS

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Title: Evidence for globally coherent variability in solar magnetic
flux emergence
Authors: Golub, L.; Vaiana, G. S.
1980ApJ...235L.119G Altcode:
We examine the large-scale spatial and temporal variations in the
emergence of X-ray bright points on the sun, in order to study the
global properties of magnetic flux emergence. Major variations in the
rate of flux emergence are observed at all solar latitudes, on a time
scale of 3-5 months. The most economical explanation of the observations
is that the full sun participated in a single large eruptive event
during the available 8 month observing period from Skylab in 1973. The
peak of this global event corresponds in time to the eruption of a
major complex of activity. Moreover, it appears that the only portion
of the solar surface which deviates from the above pattern of behavior
is the low latitude region in the vicinity of the AR complex; this area
shows a temporary depletion immediately following the AR outburst. The
high-latitude regions in both hemispheres show the same variation and
appear to lead the low-latitude emergence by approximately 1 month.

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Title: Decametric radio bursts associated with coronal loop structures
Authors: Gergely, T. E.; Kundu, M. R.; Golub, L.; Webb, D.
1980IAUS...86..435G Altcode:
The association of X-ray loop structures with type III bursts
is examined using soft X-ray (2-54 A) pictures which were obtained
from the Skylab S-054 experiment. The properties of meter-decameter
wavelength radio bursts (type III) appear to be associated with two
different kinds of loop structures: (1) short lived small scale loops,
which are found to link magnetic fields of opposite polarity, called
X-ray bright points (XBP); and (2) long lasting loop systems which
connect opposite magnetic polarities of an active region as well as
active region complexes. It is judged that the presence of active region
loop complexes on the disk is a necessary yet insufficient condition for
the occurrence of a decametric storm and that conditions concerning the
geometry of the magnetic field must also be important in the process.

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Title: X-ray Observations of the α Cen System from EINSTEIN.
Authors: Golub, L.; Harnden, F. R., Jr.; Rosner, R.; Topka, K.;
Vaiana, G. S.
1979BAAS...11..775G Altcode:
No abstract at ADS

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Title: X-ray Observations of Very Late-Type Dwarf Stars from the
EINSTEIN Observatory.
Authors: Rosner, R.; Giacconi, R.; Golub, L.; Harnden, F. R., Jr.;
Topka, K.; Vaiana, G. S.
1979BAAS...11..776R Altcode:
No abstract at ADS

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Title: On Stars and OB Associations Observed from EINSTEIN.
Authors: Harnden, F. R., Jr.; Golub, L.; Rosner, R.; Seward, F.;
Topka, K.; Vaiana, G. S.
1979BAAS...11..775H Altcode:
No abstract at ADS

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Title: A Magnitude Limited Stellar Survey with EINSTEIN.
Authors: Topka, K.; Golub, L.; Harnden, F. R., Jr.; Gorenstein, P.;
Rosner, R.; Vaiana, G. S.
1979BAAS...11..781T Altcode:
No abstract at ADS

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Title: Rapid changes in the fine structure of a coronal "Bright point"
and a small coronal "active region".
Authors: Sheeley, N. R., Jr.; Golub, L.
1979SoPh...63..119S Altcode:
A coronal `bright point' is resolved into a pattern of emission which,
at any given time, consists of 2 or 3 miniature loops (each ∼2500
km in diameter and ∼12 000 km long). During the half-day lifetime
of the `bright point' individual loops evolved on a time scale ∼6
min. A small `ctive region' seemed to evolve in this way, but the
occasional blurring together of several loops made it difficult to
follow individual changes.

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Title: Anticorrelation of X-ray bright points with sunspot number,
1970 - 1978.
Authors: Golub, L.; Davis, J. M.; Krieger, A. S.
1979ApJ...229L.145G Altcode:
Soft X-ray observations of the solar corona over the period 1970-1978
show that the number of small short-lived bipolar magnetic features
(X-ray bright points) varies inversely with the sunspot index. During
the entire period from 1973 to 1978 most of the magnetic flux emerging
at the solar surface appeared in the form of bright points. In 1970,
near the peak of solar cycle 20, the contributions from bright points
and from active regions appear to be approximately equal. These
observations strongly support an earlier suggestion that the solar
cycle may be characterized as an oscillator in wave-number space with
relatively little variation in the average total rate of flux emergence.

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Title: Observational Tests of Magnetic Field-Related Coronal Heating
Theories
Authors: Golub, L.; Maxson, C.; Rosner, R.; Serio, S.; Vaiana, G. S.
1979BAAS...11R.408G Altcode:
No abstract at ADS

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Title: The relationship between solar activity and coronal hole
evolution.
Authors: Nolte, J. T.; Davis, J. M.; Gerassimenko, M.; Krieger, A. S.;
Solodyna, C. V.; Golub, L.
1978SoPh...60..143N Altcode:
We examine the relationship between coronal hole evolution and solar
active regions during the Skylab period. We find a tendency for holes
to grow or remain stable when the activity nearby, seen as calcium
plages and bright regions in X-rays, is predominantly large, long-lived
regions. This is consistent with results of previous studies, using
somewhat different methods. We also find that there is a significantly
higher number of small, short-lived active regions, as indicated by
X-ray bright points, in the vicinity of decaying holes than there
is near other holes. We interpret this to mean that holes disappear
at least in part because they become filled with many small scale,
magnetically closed, X-ray emitting features. This interpretation,
together with the previously reported observation that the number of
X-ray bright points was much larger near solar minimum than it was
during the Skylab period, provides a possible explanation for the
disappearance of the large, near-equatorial coronal holes at the time
of solar minimum.

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Title: Heating of coronal plasma by anomalous current dissipation.
Authors: Rosner, R.; Golub, L.; Coppi, B.; Vaiana, G. S.
1978ApJ...222..317R Altcode:
It is shown that there exist heating mechanisms which connect the
observed radiative properties of the inner corona in a simple way to
the underlying solar magnetic field. The mechanisms considered involve
the generation and consequent dissipation of coronal currents. It
is argued that the spatially and temporally inhomogeneous nature
of the erupting solar magnetic field is an essential element of
coronal heating. Unlike heating theories conceived in the context
of the 'homogeneous' corona, this class of current heating models
incorporates the observed stochastic coronal structuring at the onset,
and does not view it as a complication of an otherwise straightforward
model. Attention is given to the generation of coronal currents, the
flux-tube emergence, the gradual growth and decay of active regions,
the energetics of current dissipation, current sheath geometry and
heat transport, and anomalous current dissipation.

---------------------------------------------------------
Title: Coronal Heating and Its Relation to Magnetic Field Evolution.
Authors: Golub, L.; Rosner, R.; Vaiana, G. S.
1978BAAS...10..440G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Differential rotation rates for short-lived regions of emerging
magnetic flux.
Authors: Golub, L.; Vaiana, G. S.
1978ApJ...219L..55G Altcode:
We have measured the synodic rotation rates of a sample of compact
X-ray emission features lasting from 1 day to 7 days, thus bridging
the transition between X-ray bright points and active regions. The
rotation rate is found to be a function of the lifetime, or size, of
the feature; shorter-lived smaller features rotate more slowly than
long-lived ones. The rotation rate for features lasting 2 days or less
is consistent with that of the photospheric gas. The longest-lived
features rotate at a rate about 5% higher, consistent with the sunspot
rotation rate.

---------------------------------------------------------
Title: Halpha macrospicules: identification with EUV macrospicules
and with flares in X-ray bright points.
Authors: Moore, R. L.; Tang, F.; Bohlin, J. D.; Golub, L.
1977ApJ...218..286M Altcode:
The paper presents observational evidence that two newly observed
transient solar phenomena, EUV macrospicules and X-ray bright-point
flares, are closely related. Time-lapse H-alpha filtergram observations
of the limb in quiet regions show small surgelike eruptions called
H-alpha macrospicules. From the similarity of H-alpha macrospicules
and EUV macrospicules, and from comparison of simultaneous H-alpha and
He II 304 A observations, we conclude that H-alpha macrospicules are
EUV macrospicules viewed in H-alpha, although most EUV macrospicules
are too faint in H-alpha to appear on H-alpha filtergrams of normal
exposure. From comparison of simultaneous X-ray and H-alpha observations
of flares in X-ray bright points situated on the limb, we show that
flares in X-ray bright points often produce H-alpha macrospicules.

---------------------------------------------------------
Title: Magnetic properties of X-ray bright points.
Authors: Golub, L.; Krieger, A. S.; Harvey, J. W.; Vaiana, G. S.
1977SoPh...53..111G Altcode:
Using high resolution KPNO magnetograms and sequences of simultaneous
S-054 soft X-ray solar images we have compared the properties of X-ray
bright points (XBP) and ephemeral active regions (ER). All XBP appear on
the magnetograms as bipolar features, except for very newly emerged or
old and decayed XBP. We find that the separation of the magnetic bipoles
increases with the age of the XBP, with an average emergence growth
rate of 2.2 ± 0.4 km s−1. The total magnetic flux in a
typical XBP living about 8 hr is found to be ≈ 2 x 1019
Mx. A proportionality is found between XBP lifetime and total magnetic
flux, equivalent to ≈ 1020 Mx per day of lifetime.

---------------------------------------------------------
Title: Solar cycle variation of magnetic flux emergence.
Authors: Davis, J. M.; Golub, L.; Krieger, A. S.
1977ApJ...214L.141D Altcode:
The number of X-ray bright points (XBP) has been measured from
solar X-ray images obtained during two rocket flights in 1976. When
compared with the data obtained during the Skylab mission (1973),
the number is found to be higher by a factor of 2. As the probability
of obtaining the result by chance is less than 1 in 5 million, it
is concluded that the number of XBP has increased in the three year
interval. As all other indicators of activity have decreased between
1973 and 1976, the cyclical variation of the short-lifetime end of
the magnetic-flux-emergence spectrum is out of phase with the solar
cycle as defined by active regions or sunspots. Since XBP in 1973
contributed more to the emerging magnetic flux than did active regions,
the possibility exists that the total amount of emerging magnetic flux
may be maximized at a sunspot minimum.

---------------------------------------------------------
Title: Heating of Coronal Plasma by Anomalous Current Dissipation.
Authors: Rosner, R.; Golub, L.; Vaiana, G. S.; Coppi, B.
1977BAAS....9..370R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observation of spatial and temporal variations in X-ray bright
point emergence patterns
Authors: Golub, L.; Krieger, A. S.; Vaiana, G. S.
1976SoPh...50..311G Altcode:
Observations of X-ray bright points (XBP) over a six-month interval
in 1973 show significant variations in both the number density of XBP
as a function of heliographic longitude and in the full Sun average
number of XBP from one rotation to the next. The observed increases
in XBP emergence are estimated to be quivalent to several large active
regions emerging per day for several months. The number of XBP emerging
at high latitudes also varies, in phase with the low latitude variation
and reaches a maximum approximately simultaneous with a major outbreak
of active regions. The quantity of magnetic flux emerging in the form
of XBP at high latitudes alone is estimated to be as large as the
contribution from all active regions.

---------------------------------------------------------
Title: Distribution of lifetimes for coronal soft X-ray broght points.
Authors: Golub, L.; Krieger, A. S.; Vaiana, G. S.
1976SoPh...49...79G Altcode:
We have measured the lifetimes of all compact emission features
visible on three sets of high time resolution soft X-ray images. The
spectrum of lifetimes is found to be heavily weighted toward short
lifetimes. The number of features present on the disk which live 2-48
hours is at least ten times as great as the number living more than 48
hours. The distribution of lifetimes can be fit in all three cases by
a four-parameter function N(t) = Ns exp(-t/τs)
+ NL exp(-t/τL), with τs = 8.7±0.2,
τL = 35±4 and Ns ≈ 10NL. Features
living two days or less have a very broad latitude distribution
(Golub et al., 1974, 1975) whereas nearly all longer-lived features
are found within 30° of the equator. The growth rates of long-lived vs
short-lived points are the same to within ≈ 20%, the major difference
being that long-lived points continue to grow and generally reach
larger sizes.

---------------------------------------------------------
Title: Emergence of Small-Scale Magnetic Fields on the Sun
Authors: Golub, L.; Krieger, A. S.; Vaiana, G. S.
1976BAAS....8..333G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Evolutionary Trends in the Development of Coronal Holes and
Their Relationship to the Sub Photospheric Magnetic Field
Authors: Davis, J. M.; Golub, L.
1976BAAS....8..326D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Identification of Hα Macrospicules with EUV Macrospicules
and with Flares in X-Ray Bright Points
Authors: Moore, R. L.; Tang, F.; Bohlin, J. D.; Golub, L.
1976BAAS....8..333M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comment on lifetime determination of solar features.
Authors: Golub, L.
1976SoPh...46..115G Altcode:
We propose a modification to a commonly used technique for
lifetime determination of solar features. Suggestions for practical
implementation of the method are presented. In addition, a serious
source of bias in lifetime determination from time-ordered data is
discussed.

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Title: Coronal Bright Points
Authors: Golub, L.; Krieger, A. S.; Vaiana, G. S.
1976IAUS...71..145G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observation of a Non-Uniform Component in the Distribution
of Coronal Bright Points
Authors: Golub, L.; Krieger, A. S.; Vaiana, G. S.
1975SoPh...42..131G Altcode:
The longitude distribution of X-ray bright points shows very strong
variations when plotted in a heliocentric (Carrington) coordinate
system. In addition, the latitude distribution can be interpreted as
having two components : a uniformly distributed component and one
having a distribution similar to that of active regions, occurring
mostly within ±30° of the equator.

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Title: Temperature and Density Measurements of Coronal Loops
Authors: Chase, R. C.; Golub, L.; Krieger, A.; Silk, J. K.; Vaiana,
G. S.; Zombeck, M.; Timothy, A. F.
1975BAAS....7..346C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Temporal and Spatial Properties of Coronal Bright Points
Authors: Golub, L.; Krieger, A.; Simon, R.; Vaiana, G.; Timothy, A. F.
1975BAAS....7Q.350G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The long term development of the large scale corona and the
evolution of coronal holes
Authors: Timothy, A. F.; Gerassimenko, M.; Golub, L.; Krieger, A. S.;
Petrasso, R.; Vaiana, G. S.
1975xtcg.work...93T Altcode:
The evolution of coronal holes and the typical coronal configurations
that result in the formation of a hole are investigated using
results obtained by the X-ray telescope experiment on the Apollo
Telescope Mount. The evolution of one particular hole is traced,
the magnetic-field configuration associated with it is examined,
and its rotational characteristics between 20 deg S and 50 deg N are
analyzed. It is found that coronal holes form in bands of unipolar
magnetic field bounded by areas of opposite polarity when patterns of
emerging active-region flux produce the appropriate large-scale field
pattern. The holes are shown to have lifetime in excess of five solar
rotations and to die when the large-scale field pattern is distorted. It
is suggested that the observed rigid rotation of a hole, which is in
contrast to the differential rotation of the field associated with it,
may be explained by the fact that the hole is a source of a recurrent
high-velocity solar-wind stream.

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Title: Time Variations of Solar X-Ray Bright Points
Authors: Golub, L.; Kriegher, A. S.; Silk, J. K.; Timothy, A. F.;
Vaiana, G. S.
1975IAUS...68...23G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Skylab and the ASE X-ray telescope experiment - A new view
of the X-ray corona
Authors: Vaiana, G. S.; Chase, R.; Davis, J.; Gerassimenko, M.; Golub,
L.; Kahler, S.; Krieger, A. S.; Petrasso, R.; Silk, J. K.; Simon, R.
1975xtcg.work....3V Altcode:
A broad description of the Skylab X-ray telescope experiment is
given. The design and development of the S-054 X-ray telescope and
the X-ray imaging system are reviewed, and the primary telescope is
described along with its spectral characteristics, imaging optics,
camera, and film. The technique for determining the temperature and
emission integral of the coronal plasma from X-ray photographs is
outlined. Data are presented on the long-term variation of large-scale
coronal structures, the evolution of active regions, and observations
of coronal holes and bright points. It is shown that active regions
undergo short-term changes related to changes in the photospheric
magnetic fields as well as long-term changes in large-scale structure,
that the decay of active regions probably contributes to the formation
of coronal holes, and that bright points are a distinct class of flaring
active regions which seem to be distributed uniformly over the sun.

---------------------------------------------------------
Title: Skylab and the ASE X-ray telescope experiment: a new view of
the X-ray corona.
Authors: Vaiana, G. S.; Chase, R.; Davis, J.; Gerassimenko, M.;
Golub, L.; Kahler, S.; Krieger, A. S.; Petrasso, R.; Silk, J. K.;
Simon, R.; Timothy, A. F.; Zombeck, M.; Webb, D.
1975MmArc.104....3V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The long term development of the large scale corona and the
evolution of coronal holes.
Authors: Timothy, A. F.; Gerassimenko, M.; Golub, L.; Krieger, A. S.;
Petrasso, R.; Vaiana, G. S.
1975MmArc.104...93T Altcode:
No abstract at ADS

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Title: Soft X-ray imaging on photographic film.
Authors: Haggerty, R.; Simon, R.; Golub, L.; Silk, J. K.; Timothy,
A. F.; Krieger, A. S.; Vaiana, G. S.
1975AASPB..10....8H Altcode:
No abstract at ADS

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Title: Solar X-Ray Bright Points
Authors: Golub, L.; Krieger, A. S.; Silk, J. K.; Timothy, A. F.;
Vaiana, G. S.
1974ApJ...189L..93G Altcode:
Preliminary analysis of photographs from the 8-054 X-ray telescope
aboard Skylab has shown that bright points have a statistical
distribution of lifetimes with a mean of eight hours. The lifetime
of a bright point is approximately proportional to its maximum area,
which is typically 2 X 108 km2. A small bright core generally develops
during the middle part of the bright-point lifetime with area 10
km2. A small fraction of bright points are seen to increase their
surface brightness by several orders of magnitude on a time scale of
minutes. These "flares" occur at all latitudes from the equator to the
poles. To first order, bright points are uniformly distributed across
the solar surface. An estimated 1500 X-ray bright points emerge per
day, possibly bringing more new magnetic flux to the surface than is
contributed by the major active regions. Sukiect headings: X-rays, solar

---------------------------------------------------------
Title: Radon Emanation from the Moon, Spatial and Temporal Variability
Authors: Gorenstein, Paul; Golub, Leon; Bjorkholm, Paul
1974Moon....9..129G Altcode:
Observations of the lunar surface with the orbiting Apollo Alpha
Particle Spectrometer during the Apollo 15 and Apollo 16 missions
have shown spatial and temporal variations in radon emission. There
are a number of well localized features in the spatial distribution of
lunar222Rn and her daughter210Po which apparently
correlate with sites of reported transient visual events. There are
sources at Aristarchus, Grimaldi and possibly Tsiolkovsky. Activity
of210Po shows enhancement at most maria edges at rates far in
excess of222Rn activity. This demonstrates unequivocally the
presence of time varying radon activity at the maria edges, taking place
at the present time. The increased radon emission is probably caused
by sporadic internal activity. In analogy to terrestial processes,
radon may be merely a trace component accompanying the release of
larger quantities of more common gases to the lunar surface.

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Title: Temporal Behavior of the Coronal Structure of Active Regions
Authors: Krieger, A.; Golub, L.; Silk, J. K.; Timothy, A.; Vaiana,
G.; Webb, D.
1974BAAS....6..290K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Coronal Bright Points
Authors: Golub, L.; Chase, R.; Krieger, A.; Silk, J. K.; Timothy,
A.; Vaiana, G.
1974BAAS....6R.287G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar X-ray bright points.
Authors: Timothy, A.; Golub, L.; Krieger, A.; Silk, J. K.; Vaiana, G.
1974BAAS....6..265T Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Detection of Radon Emission at the Edges of Lunar Maria with
the Apollo Alpha-Particle Spectrometer
Authors: Gorenstein, Paul; Golub, Leon; Bjorkholm, Paul
1974Sci...183..411G Altcode:
The distribution of radioactive polonium-210, a decay product
of radon-222, shows enhanced concentrations at the edges of lunar
maria. Enhancements are seen at the edges of Mare Fecunditatis, Mare
Crisium, Mare Smythii, Mare Tranquillitatis, Mare Nubium, Mare Cognitum,
and Oceanus Procellarum. The observation is indicative of the transient
emission of radon gas from the perimeters of lunar maria.

---------------------------------------------------------
Title: Radon emanation from the moon: spatial and temporal
variability.
Authors: Gorenstein, P.; Golub, L.; Bjorkholm, P.
1974spre.conf..653G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dynamic Events in the X-Ray Corona (a Progress Report from
the AS&amp;E X-Ray Telescope on Skylab)
Authors: Gerassimenko, M.; Golub, L.; Kahler, S.; Petrasso, R.
1974IAUS...57..501G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dynamic events in the X-ray corona. (A progress report from
the AS&amp;E X-ray telescope on Skylab).
Authors: Vaiana, G. S.; Krieger, A. S.; Silk, J. K.; Timothy, A. F.;
Chase, R. C.; Davis, J.; Gerassimenko, M.; Golub, L.; Kahler, S.;
Petrasso, R.
1974IAUS...57..501V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Long Term Development of the Large Scale Corona and the
Evolution of Coronal Holes
Authors: Timothy, A. F.; Gerassimenko, M.; Golub, L.; Krieger, A. S.;
Petrasso, R.; Vaiana, G. S.
1974OMOAA.104...93T Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Detection of a Nonuniform Distribution of Polonium-210 on
the Moon with the Apollo 16 Alpha Particle Spectrometer
Authors: Bjorkholm, Paul; Golub, Leon; Gorenstein, Paul
1973Sci...180..957B Altcode:
The polonium-210 activity of the lunar surface is significantly larger
than the activity of its progenitor radon-222. This result establishes
unequivocally that radon emanation from the present-day moon varies
considerably within the 21-year half-life of lead-210, the parent
nuclide of polonium-210. There are large variations and well-localized
enhancements in polonium-210 activity over much of the moon's surface.

---------------------------------------------------------
Title: Spatial Non-Homogeneity and Temporal Variability in the
Emanation of Radon from the Lunar Surface: Interpretation
Authors: Gorenstein, P.; Golub, L.; Bjorkholm, P.
1973LPI.....4..307G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Distribution of 210PO Across the Apollo 16 Groundtrack and
Correlation with Lunar Surface Features
Authors: Golub, L.; Bjorkholm, P. J.; Gorenstein, P.
1973LPI.....4..302G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Detection of Radon Emanation from the Lunar Regolith during
Apollo 15 and 16
Authors: Bjorkholm, P.; Golub, L.; Gorenstein, P.
1973LPI.....4...78B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Distribution of 222Rn and 210Po on the
lunar surface as observed by the alpha particle spectrometer
Authors: Bjorkholm, P. J.; Golub, L.; Gorenstein, P.
1973LPSC....4.2793B Altcode: 1973GeCAS...4.2793B
No abstract at ADS

---------------------------------------------------------
Title: Spatial features and temporal variability in the emission
of radon from the moon: An interpretation of results from the alpha
particle spectrometer
Authors: Gorenstein, P.; Golub, L.; Bjorkholm, P. J.
1973LPSC....4.2803G Altcode: 1973GeCAS...4.2803G
No abstract at ADS

---------------------------------------------------------
Title: X-Ray Fluorescence Experiment
Authors: Adler, I.; Trombka, J.; Gerard, J.; Lowman, P.; Schmadebeck,
R.; Blodget, H.; Eller, E.; Yin, L.; Lamothe, R.; Osswald, G.;
Gorenstein, P.; Bjorkholm, P.; Gursky, H.; Harris, B.; Golub, L.;
Harnden, F. R., Jr.
1972NASSP.315..191A Altcode:
No abstract at ADS