explanation blue bibcodes open ADS page with paths to full text
Author name code: tomczyk
ADS astronomy entries on 2022-09-14
author:"Tomczyk, Steven"
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Title: Magnetoseismology for the solar corona: from 10 Gauss to
coronal magnetograms
Authors: Yang, Zihao; Gibson, Sarah; He, Jiansen; Del Zanna, Giulio;
Tomczyk, Steven; Morton, Richard; McIntosh, Scott; Wang, Linghua;
Karak, Bidya Binay; Samanta, Tanmoy; Tian, Hui; Chen, Yajie; Bethge,
Christian; Bai, Xianyong
2022cosp...44.2490Y Altcode:
Magnetoseismology, a technique of magnetic field diagnostics based
on observations of magnetohydrodynamic (MHD) waves, has been widely
used to estimate the field strengths of oscillating structures in
the solar corona. However, previously magnetoseismology was mostly
applied to occasionally occurring oscillation events, providing
an estimate of only the average field strength or one-dimensional
distribution of field strength along an oscillating structure. This
restriction could be eliminated if we apply magnetoseismology to the
pervasive propagating transverse MHD waves discovered with the Coronal
Multi-channel Polarimeter (CoMP). Using several CoMP observations of
the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
the plasma density and wave phase speed in the corona, which allow us
to map both the strength and direction of the coronal magnetic field
in the plane of sky. We also examined distributions of the electron
density and magnetic field strength, and compared their variations
with height in the quiet Sun and active regions. Such measurements
could provide critical information to advance our understanding of the
Sun's magnetism and the magnetic coupling of the whole solar atmosphere.
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Title: Magnetic Field Measurements in the Large Scale Solar Corona
Authors: Tomczyk, S.; Gibson, S. E.; Cosmo Team
2022heli.conf.4031T Altcode:
Daily measurements of the magnetic structure of the global solar
corona are needed to advance our understanding of critical physical
processes. The COSMO 1.5-m Large Coronagraph will enable coronal
magnetic field observations.
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Title: First Images from the Upgraded Coronal Multi-channel
Polarimeter (UCoMP)
Authors: Tomczyk, Steven; Landi, Enrico; Berkey, Ben; Burkepile,
Joan; Cotter, Marc; Gallaher, Dennis; Galloy, Michael D.; Graves,
Rob; Oakley, Philip; Perez-Gonzalez, Lisa; Sewell, Scott; de Toma,
Giuliana; Zmarzly, Patrick
2021AGUFMSH15G2089T Altcode:
The Upgraded Coronal Multi-channel Polarimeter (UCoMP) is a coronal
polarimeter with a narrow-band tunable birefringent filter capable
of imaging the intensity, full Stokes polarization, and Doppler shift
across the coronal emission lines of FeXIV 530.3 nm, FeX 637.4 nm, ArXI
691.8, FeXV 706.2 nm, FeXI 789.4, FeXIII 1074.7 and 1079.8 nm and the
chromospheric emission lines of HI 656.3 and HeI 1083 nm. The UCoMP is
an upgrade of the CoMP instrument. It has a broader wavelength range
(530 - 1083 nm) than CoMP (1074 - 1083 nm) increasing the number of
available emission lines in order to observe the corona over a wide
range of temperatures, a larger field-of-view (+/- 2 Rsun) compared
to CoMP (+/- 1.3 Rsun), and higher spatial resolution (6 arcseconds)
compared to CoMP (9 arcseconds). The UCoMP demonstrates the technology
of a large aperture (50 mm) tunable birefringent filter based on Lithium
Niobate crystals and is a pathfinder instrument for the Coronal Solar
Magnetism Observatory. The instrument was shipped to Mauna Loa Solar
Observatory in December of 2020, installed in the Spring of 2021, and
started taking data May 26, 2021, followed by four months of instrument
commissioning. This talk will describe the instrument and present the
first images taken with the UCoMP.
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Title: Magnetoseismology for the solar corona: from 10 Gauss to
coronal magnetograms
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
Morton, Richard; Del Zanna, Giulio; McIntosh, Scott; Karak, Bidya
Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie; Bai,
Xianyong; Wang, Linghua
2021AGUFMSH12C..07Y Altcode:
Magnetoseismology, a technique of magnetic field diagnostics based
on observations of magnetohydrodynamic (MHD) waves, has been widely
used to estimate the field strengths of oscillating structures in
the solar corona. However, previously magnetoseismology was mostly
applied to occasionally occurring oscillation events, providing
an estimate of only the average field strength or one-dimensional
distribution of field strength along an oscillating structure. This
restriction could be eliminated if we apply magnetoseismology to the
pervasive propagating transverse MHD waves discovered with the Coronal
Multi-channel Polarimeter (CoMP). Using several CoMP observations of
the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
the plasma density and wave phase speed in the corona, which allow us
to map both the strength and direction of the coronal magnetic field
in the plane of sky. We also examined distributions of the electron
density and magnetic field strength, and compared their variations
with height in the quiet Sun and active regions. Such measurements
could provide critical information to advance our understanding of the
Sun's magnetism and the magnetic coupling of the whole solar atmosphere.
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Title: The COMPLETE mission concept for the Heliophysics Decadal
Survey
Authors: Seaton, Daniel; Caspi, Amir; Casini, Roberto; Downs, Cooper;
Gibson, Sarah; Gilbert, Holly; Glesener, Lindsay; Guidoni, Silvina;
Hughes, Marcus; Reeves, Katharine; Shih, Albert; Tomczyk, Steven;
West, Matthew
2021AGUFMSH52A..08S Altcode:
We present the COMPLETE mission concept, currently under study for
the upcoming Heliophysics Decadal Survey. COMPLETE would provide the
first comprehensive measurements of the 3D low-coronal magnetic field
and simultaneous 3D energy release diagnostics from large eruptions
(flares and CMEs) down to small-scale processes (coronal heating and
solar wind outflows). COMPLETE's measurements will finally allow closure
on the long-standing question of exactly how energy is stored, released,
and transported in impulsive events at all scales. COMPLETE comprises
an instrument suite with hard and soft X-ray spectral imagers, gamma-ray
and energetic neutral atom spectral imagers, high-resolution wide-field
EUV filtergram imagers, photospheric Doppler vector magnetographs,
and Hanle-effect UV (Ly-a) coronal magnetographs. Distributed across
three spacecraft at the L1, L4, and L5 Earth-Sun Lagrange points, the
suite on each spacecraft is optimized for the measurements from that
vantage point and for the mission as a whole. Data from all instruments
will be processed to enable systems-level analysis from the entire
observatory. COMPLETE instrument suite is deliberately complementary
across its individual spacecraft, with overlapping fields of view and
optimized capabilities to provide a zone of ideal coverage near the
west limb as viewed from Earth. Within this region COMPLETE provides
comprehensive observations of 3D structures, photospheric and coronal
magnetic fields, and signatures of impulsive energy release within
integrated data products. The COMPLETE mission concept, and the science
and data analysis techniques it espouses, represent a strategic shift
from the nearly ubiquitous current practices of siloed study in isolated
subdisciplines to a comprehensive, unified systems approach to solar,
coronal, and heliophysics.
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Title: Calibration of a Visible-Light Prototype for the CORSAIR
Polarimeter
Authors: Bruce, Sarah; Samra, Jenna; Cheimets, Peter; Tomczyk, Steven;
Kramar, Maxim
2021AGUFMSH55B1838B Altcode:
The coronal magnetic field creates the structure of the corona and is
the source of heat and energy for CMEs & solar flares. Studying the
polarized light emitted by the corona allows for a better understanding
of the coronal magnetic field, which produces measurable signals in
the linear & circular polarization through the saturated Hanle
effect and the Zeeman effect. These signals are difficult to measure
because they are 10 to 10,000 times weaker than the intensity. The
Coronal Spectropolarimeter for Airborne Infrared Research (CORSAIR)
is a coronagraph, polarimeter, and grating spectrometer that provides
two-dimensional spectropolarimetric imaging up to one solar radius from
the limb. It is designed to measure the solar coronas full polarization
state integrated along the line of sight. The CORSAIR polarimeter
comprises a rotating wave plate followed by a fixed linear polarizer
(analyzer). The multi-order wave plate provides high polarimetric
efficiency across five lines with wavelengths from 1-4 microns. In
order to establish a calibration scheme for the CORSAIR polarimeter and
explore the issues related to using a multi-order wave plate, we have
prototyped the polarimeter in visible light. The prototype operates
at 532 nm and 670 nm with a wave plate retardance of just over 17
waves and 13 waves, similar to the retardance of the IR wave plate at
1074.7 nm (Fe XIII) and 1430.5 nm (Si X). The prototyped calibration
unit consists of a linear polarizer and a rotating quarter wave plate
(QWP) at each wavelength. The polarimeter is calibrated by rotating the
QWP 180 degrees for each rotation angle of the polarimeter wave plate,
producing a set of modulation and demodulation matrices and associated
efficiencies. Due to manufacturing imperfections and other real-world
effects, we see small differences between the calibrated and modeled
modulation matrices, which have the potential to completely change
the resulting linear and circular polarization. We use a model of the
full coronal polarization state to explore the effect of polarimeter
calibration on the measured linear and circular polarization and define
the required calibration accuracy for the IR polarimeter. This work is
supported by the NSF-REU Solar Physics program at SAO, grant number
AGS-1850750, & the CORSAIR contract, grant number 80NSSC21K0809
from NASA to SAO.
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Title: Understanding the coronal origins of global heliospheric
phenomena through 3D measurements with COMPLETE
Authors: Caspi, Amir; Seaton, Daniel; Casini, Roberto; Downs, Cooper;
Gibson, Sarah; Gilbert, Holly; Glesener, Lindsay; Guidoni, Silvina;
Hughes, Marcus; Reeves, Katharine; Shih, Albert; Tomczyk, Steven;
West, Matthew
2021AGUFMSH25F2151C Altcode:
Impulsive solar eruptions (flares, coronal mass ejections) and more
gradual energetic processes (coronal heating in active regions, solar
wind outflows) are powered and governed by the Sun's complex coronal
magnetic field. The evolution of these events in the low and middle
corona has direct impact on global scales throughout the corona and
heliosphere, including as drivers of space weather that affect human
and technological assets, but a coherent understanding of globally
connected behavior necessarily requires understanding its origins at
the Sun. Despite many decades of research, it is still poorly understood
exactly how magnetic energy is stored and impulsively released to power
plasma heating, particle acceleration, and bulk flows. Breakthroughs
have been hindered by two critical limitations: lack of knowledge of
the 3D coronal magnetic field and its evolution, and a similar lack
of insight into how localized energy release manifests and propagates
within 3D coronal structures. Transformative progress to close these
gaps requires systematic observations from multiple viewpoints, in a
variety of wavelengths, and including coronal magnetometry. Recent and
ongoing technological advancements allow us to realize these goals
within a decadal timescale. To that end, we present the COMPLETE
mission concept, currently under study for the upcoming Heliophysics
Decadal Survey. COMPLETEs highly co-optimized and complementary
instrument suite include spectroscopic imagers for X-rays, gamma-rays,
and energetic neutral atoms; high-resolution wide-field EUV filtergram
imagers; photospheric Doppler vector mangetographs; and Hanle-effect UV
(Lyman-alpha) coronal magnetographs. Distributed across three spacecraft
at the L1, L4, and L5 Earth-Sun Lagrange points, COMPLETE would provide
the first comprehensive measurements of the 3D low- and middle-coronal
magnetic field and simultaneous 3D energy-release diagnostics from
large eruptions down to small-scale processes. COMPLETE represents
a strategic shift towards a comprehensive, unified systems approach
to solar, coronal, and heliospheric physics, to enable us to finally
close decades-old questions of how the Suns magnetic field and impulsive
energy release are interrelated, from local to global scales.
---------------------------------------------------------
Title: Mapping the global magnetic field in the solar corona through
magnetoseismology
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
Morton, Richard; Del Zanna, Giulio; McIntosh, Scott; Karak, Bidya
Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie;
Wang, Linghua; Bai, Xianyong
2021EGUGA..23..642Y Altcode:
Magnetoseismology, a technique of magnetic field diagnostics based
on observations of magnetohydrodynamic (MHD) waves, has been widely
used to estimate the field strengths of oscillating structures in
the solar corona. However, previously magnetoseismology was mostly
applied to occasionally occurring oscillation events, providing
an estimate of only the average field strength or one-dimensional
distribution of field strength along an oscillating structure. This
restriction could be eliminated if we apply magnetoseismology to the
pervasive propagating transverse MHD waves discovered with the Coronal
Multi-channel Polarimeter (CoMP). Using several CoMP observations of
the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
the plasma density and wave phase speed in the corona, which allow us
to map both the strength and direction of the coronal magnetic field
in the plane of sky. We also examined distributions of the electron
density and magnetic field strength, and compared their variations
with height in the quiet Sun and active regions. Such measurements
could provide critical information to advance our understanding of the
Sun's magnetism and the magnetic coupling of the whole solar atmosphere.
---------------------------------------------------------
Title: Electron Densities in the Solar Corona Measured Simultaneously
in the Extreme Ultraviolet and Infrared
Authors: Dudík, Jaroslav; Del Zanna, Giulio; Rybák, Ján;
Lörinčík, Juraj; Dzifčáková, Elena; Mason, Helen E.; Tomczyk,
Steven; Galloy, Michael
2021ApJ...906..118D Altcode: 2020arXiv201109175D
Accurate measurements of electron density are critical for
determination of the plasma properties in the solar corona. We compare
the electron densities diagnosed from Fe XIII lines observed by the
Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode
mission with the near-infrared (NIR) measurements provided by the
ground-based Coronal Multichannel Polarimeter (CoMP). To do that, the
emissivity-ratio method based on all available observed lines of Fe
XIII is used for both EIS and CoMP. The EIS diagnostics is further
supplemented by the results from Fe XII lines. We find excellent
agreement, within 10%, between the electron densities measured from both
extreme-ultraviolet and NIR lines. In the five regions selected for
detailed analysis, we obtain electron densities of log(N<SUB>e</SUB>
[cm<SUP>-3</SUP>]) = 8.2-8.6. Where available, the background
subtraction has a significant impact on the diagnostics, especially on
the NIR lines, where the loop contributes less than a quarter of the
intensity measured along the line of sight. For the NIR lines, we find
that the line center intensities are not affected by stray light within
the instrument, and recommend using these for density diagnostics. The
measurements of the Fe XIII NIR lines represent a viable method for
density diagnostics using ground-based instrumentation.
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Title: Coronagraphy from the Ground: Current and Future Observations
Authors: Burkepile, J.; Tomczyk, S.; Zmarzly, P.; de Wijn, A.; Gibson,
S. E.; de Toma, G.; Galloy, M. D.
2020AGUFMSH031..03B Altcode:
Ground-based coronagraphs provided the first observations of the
ethereal corona outside of a total solar eclipse in 1931. Invented by
Bernard Lyot, coronagraphs enabled long time-series images and movies
of the emission line corona. Advances in technology have led to more
sophisticated coronagraphs capable of observing polarized light from
spectral lines and the coronal continuum. These observations, coupled
with advances in our understanding of resonance scattering-induced
polarization, have greatly facilitated our knowledge of coronal physics
and explosive events such as Coronal Mass Ejections (CMEs). While
space-based coronagraphs provide spectacular observations of the
extended corona, ground-based coronagraphs continue to contribute
important, unique and complementary inner coronal observations at
a fraction of the cost of a space-based mission. We discuss current
ground-based solar coronagraphs, observations and data products and
highlight future instruments and network capabilities and benefits.
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Title: Untangling the global coronal magnetic field with
multiwavelength observations
Authors: Gibson, S. E.; Malanushenko, A.; de Toma, G.; Tomczyk, S.;
Reeves, K.; Tian, H.; Yang, Z.; Chen, B.; Fleishman, G.; Gary, D.;
Nita, G.; Pillet, V. M.; White, S.; Bąk-Stęślicka, U.; Dalmasse,
K.; Kucera, T.; Rachmeler, L. A.; Raouafi, N. E.; Zhao, J.
2020arXiv201209992G Altcode:
Magnetism defines the complex and dynamic solar corona. Coronal
mass ejections (CMEs) are thought to be caused by stresses, twists,
and tangles in coronal magnetic fields that build up energy and
ultimately erupt, hurling plasma into interplanetary space. Even the
ever-present solar wind possesses a three-dimensional morphology shaped
by the global coronal magnetic field, forming geoeffective corotating
interaction regions. CME evolution and the structure of the solar
wind depend intimately on the coronal magnetic field, so comprehensive
observations of the global magnetothermal atmosphere are crucial both
for scientific progress and space weather predictions. Although some
advances have been made in measuring coronal magnetic fields locally,
synoptic measurements of the global coronal magnetic field are not yet
available. We conclude that a key goal for 2050 should be comprehensive,
ongoing 3D synoptic maps of the global coronal magnetic field. This will
require the construction of new telescopes, ground and space-based,
to obtain complementary, multiwavelength observations sensitive
to the coronal magnetic field. It will also require development of
inversion frameworks capable of incorporating multi-wavelength data,
and forward analysis tools and simulation testbeds to prioritize and
establish observational requirements on the proposed telescopes.
---------------------------------------------------------
Title: Mapping the magnetic field in the solar corona through
magnetoseismology
Authors: Yang, ZiHao; Tian, Hui; Tomczyk, Steven; Morton, Richard;
Bai, XianYong; Samanta, Tanmoy; Chen, YaJie
2020ScChE..63.2357Y Altcode: 2020arXiv200803146Y
Magnetoseismology, a technique of magnetic field diagnostics based
on observations of magnetohydrodynamic (MHD) waves, has been widely
used to estimate the field strengths of oscillating structures in
the solar corona. However, previously magnetoseismology was mostly
applied to occasionally occurring oscillation events, providing
an estimate of only the average field strength or one-dimensional
distribution of field strength along an oscillating structure. This
restriction could be eliminated if we apply magnetoseismology to the
pervasive propagating transverse MHD waves discovered with the Coronal
Multi-channel Polarimeter (CoMP). Using several CoMP observations of
the Fe xiii 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
the plasma density and wave phase speed in the corona, which allow us
to map both the strength and direction of the coronal magnetic field
in the plane of sky. We also examined distributions of the electron
density and magnetic field strength, and compared their variations
with height in the quiet Sun and active regions. Such measurements
could provide critical information to advance our understanding of the
Sun's magnetism and the magnetic coupling of the whole solar atmosphere.
---------------------------------------------------------
Title: Global maps of the magnetic field in the solar corona
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
Morton, Richard; Del Zanna, Giulio; McIntosh, Scott W.; Karak, Bidya
Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie;
Wang, Linghua
2020Sci...369..694Y Altcode: 2020arXiv200803136Y
Understanding many physical processes in the solar atmosphere requires
determination of the magnetic field in each atmospheric layer. However,
direct measurements of the magnetic field in the Sun’s corona are
difficult to obtain. Using observations with the Coronal Multi-channel
Polarimeter, we have determined the spatial distribution of the
plasma density in the corona and the phase speed of the prevailing
transverse magnetohydrodynamic waves within the plasma. We combined
these measurements to map the plane-of-sky component of the global
coronal magnetic field. The derived field strengths in the corona,
from 1.05 to 1.35 solar radii, are mostly 1 to 4 gauss. Our results
demonstrate the capability of imaging spectroscopy in coronal magnetic
field diagnostics.
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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.
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Title: Tomographic Measurements of Magnetic Free Energy in CME
Source Regions
Authors: Lin, H.; Kramar, M.; Tomczyk, S.
2019AGUFMSH53B3378L Altcode:
Magnetic free energies (MFEs) contained in highly non-potential coronal
magnetic field in active regions are believed to be the primary source
of energy of solar eruptions. Recent progresses in observational
capabilities and tomographic inversion techniques have allowed us
to directly determine the 3D structures of the temperature, density
and magnetic fields of the solar corona (Kramar et al., 2016) using
space EUV coronal emission line (CEL) data and ground-based synoptic
IR CELs polarization observations. The magnetic free energy of the
solar corona can now be directly derived from these observationally
determined coronal models. We will present measurements of the MFEs at
the source regions of coronal mass ejections (CMEs) and comparisons of
the MFEs with direct measurements of kinetic energies of the CMEs. These
studies will help us understand the energetics of the solar eruptions.
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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: 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. <P />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. <P />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.
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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 R<SUB>Sun</SUB>
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. <P />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).
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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: 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: Upgraded Coronal Multi-channel Polarimeter (UCoMP)
Authors: Tomczyk, Steven; Landi, Enrico
2019shin.confE.131T Altcode:
The Coronal Multi-channel Polarimeter (CoMP) is a coronal polarimeter
with a narrow-band tunable Lyot filter capable of imaging the intensity,
polarization and Doppler shift in the coronal emission lines of FeXIII
1074.7 and 1079.8 nm and HeI 1083 nm. We are currently in the process
of upgrading the CoMP instrument to 1) broaden the wavelength range
to 530 - 1083 nm to increase of emission lines that can be observed
to 9 in order to enhance the plasma diagnostic capabilities of the
CoMP, 2) increase the field-of-view to 1 degree, and 3) increase the
spatial resolution. This poster will describe the upgrade and focus
on the enhanced scientific capabilities of the UCoMP. The UCoMP will
be deployed in September of 2019.
---------------------------------------------------------
Title: High-cadence Visible and Infrared Spectra of the Sun during
Eclipse
Authors: Judge, P.; Tomczyk, S.; Hannigan, J.; Sewell, S.
2019ApJ...877...10J Altcode:
We study novel spectra from 310 nm to 5.5 μm obtained during the
2017 August 21 eclipse. Four spectrometers were deployed at Camp
Wyoba (altitude 2402 m) on Casper Mountain, WY. Three low-resolution
({ \mathcal R } ≲ 1000) Avantes spectrometers obtained useful
spectra from 310 nm to 2.3 μm, at cadences from 8 to 500 ms. To
maximize photometric precision, these instruments were fed with
optical fibers placed in the pupil planes of two small (D = 5 cm)
telescopes, thereby integrating all light from the field of view. We
also acquired higher-resolution ({ \mathcal R } ≈ 30000) spectra with
a new infrared Fourier Transform Spectrometer, fed by a Sun-tracking
heliostat, at a 2.5 s cadence. We calibrate the fluxes using counts
obtained during partial eclipse, with known limb-darkened photospheric
intensities. Fluxes of chromospheric lines, including Ca II H, K, and
Hα, obtained near third contact, were measured every 20 ms, a sampling
in height above the limb of 5.6 km. The behavior found corresponds to
that found in traditional (image-plane) flash spectra. Two unknown
chromospheric emission lines are noted. Based upon our measurements
and earlier calculations, we propose new eclipse experiments to uncover
clues to the origin and structure of spicules.
---------------------------------------------------------
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: Investigating Coronal Magnetism with COSMO: Science on
the Critical Path To Understanding The "Weather" of Stars and
Stellarspheres
Authors: McIntosh, Scott; Tomczyk, Steven
2019BAAS...51c.407M Altcode: 2019astro2020T.407M
The white paper discusses the measurement of coronal magnetism as
a gateway to improving our understanding of the heliosphere, drive
improvements in space weather and ultimately understanding stellar
coronae and stellar weather.
---------------------------------------------------------
Title: Experimental Testing of Scattering Polarization Models
Authors: Li, W.; Casini, R.; Tomczyk, S.; Landi Degl'Innocenti, E.;
Marsell, B.
2018ApJ...867L..22L Altcode: 2018arXiv181107090L
We realized a laboratory experiment to study the scattering polarization
of the Na I D-doublet at 589.0 and 589.6 nm in the presence of a
magnetic field. This work was stimulated by solar observations of
that doublet, which have proven particularly challenging to explain
through available models of polarized line formation, even to the
point of casting doubts on our very understanding of the underlying
physics. The purpose of the experiment was to test a quantum theory
for the polarized scattering of spectrally flat incident radiation, on
which much of the current magnetic diagnostics of stellar atmospheres
is based. The experiment has confirmed the predictions of that theory,
and its adequacy for the modeling of scattering polarization under
flat-spectrum illumination.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory
Authors: Thompson, Michael J.; Tomczyk, Steven; Gibson, Sarah E.;
McIntosh, Scott W.; Landi, Enrico
2018IAUS..335..359T Altcode:
The Coronal Solar Magnetism Observatory (CoSMO) is a proposed new
facility led by the High Altitude Observatory and a consortium of
partners to measure magnetic field and plasma properties in a large
(one degree) field of view extending down to the inner parts of the
solar corona. CoSMO is intended as a research facility that will
advance the understanding and prediction of space weather. The
instrumentation elements of CoSMO are: a white-light coronagraph
(KCor), already operational at the Mauna Loa Solar Observatory
(MLSO); the Chromosphere and Prominence Magnetometer (ChroMag), due
for deployment to MLSO next year; and the CoSMO Large Coronagraph (LC)
which has completed Preliminary Design Review.
---------------------------------------------------------
Title: The eruption of a prominence carrying coronal flux rope:
forward synthesis of the magnetic field strength measurement by the
COronal Solar Magnetism Observatory Large Coronagraph
Authors: Fan, Yuhong; Gibson, Sarah; Tomczyk, Steven
2018cosp...42E1038F Altcode:
From a magnetohydrodynamic (MHD) simulation of the eruption of
prominence hosting coronal flux rope, we carry out forward synthesis
of the circular polarization signal V/I produced by the MHD model as
measured by the proposed COronal Solar Magnetism Observatory (COSMO)
Large Coronagraph (LC) and infer the line-of-sight magnetic field
BLOS above the limb. With an aperture of 150 cm, integration time of
300 sec, and an observation pixel of 12 arcsec, the LC can measure
a significant BLOS with sufficient signal to noise level, from the
simulated flux rope with a peak azimuthal field strength of about
10 G. The measured BLOS is found to relate well with the axial field
strength of the flux rope within the height range of the prominence,
and can discern the increase with height of the magnetic field strength
along the prominence that is a definitive signature of the concave
upturning dipped field supporting the prominence. The measurement
can also detect above the noise the outward rise of the BLOS due to
the slow rise of the flux rope as it develops the kink instability,
during the phase when its rise speed is still below 15 km/s and up to a
height of about 1.25 solar radius. These results suggest that the COSMO
LC has great potential in providing quantitative information about
the magnetic field structure of CME precursors (such as prominences)
and their early evolution for the onset of eruption.
---------------------------------------------------------
Title: The coronal magnetic field derived by vector tomography from
IR and UV measurements
Authors: Kramar, Maxim; Tomczyk, Steven; Lin, Haosheng
2018cosp...42E1830K Altcode:
One of the major problems in solar physics is to measure the
coronal magnetic fields before and during the coronal transients
events. Spectropolarimetric coronal observations of magnetically
sensitive spectral lines provide an information about the magnetic
field. However, inversion of the magnetic field from such types of
measurements is not straightforward due to the nature of the line
formation mechanisms and the fact that the coronal is optically
thin. Because of the latter it is generally not possible to spatially
resolve the coronal field over the line of sight (LOS). Tomography,
i.e. observations form multiple LOSe, is required. We applied the vector
tomography technique to measurements of the Fe XIII 10747 A Hanle effect
linear polarization obtained by the Coronal Multichannel Polarimeter
(CoMP). The photospheric observations and divergenceless of the field
were used as additional constraints in the tomographic inversion. The
inversion method also requires to know the 3D distribution of the
coronal electron density and temperature which have been reconstructed
by scalar field tomography based on STEREO/EUVI data. The obtained 3D
coronal magnetic field has been validated by relating its structures
(streamers, pseudostreamers, coronal holes) to the STEREO/EUVI images
and to the global 3D coronal electron density obtained by tomography
based on STEREO/COR1 data. Also, we explore how the inclusion of
circular polarization IR measurements of the coronal Zeeman effect
(together with the linear polarization measurements of the Hanle
effect) into the inversion will affect the quality of the magnetic
field reconstruction.
---------------------------------------------------------
Title: New Coronal Science from NASA WB-57F High-Altitude Aircraft
Observations of the 2017 Total Solar Eclipse
Authors: Caspi, Amir; DeLuca, . Edward; Tomczyk, Steven; DeForest,
Craig; Bryans, Paul; Seaton, Daniel; Tsang, Constantine
2018cosp...42E.526C 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 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" telescopes feeding high-sensitivity visible
(green line and nearby continuum) and medium-wave IR (3-5 {μ}m) 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 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: Turbulence and Heating in the Flank and Wake Regions of a
Coronal Mass Ejection
Authors: He, Jiansen; Song, Hong-Qiang; Tomczyk, Steven; Wang, Linghua;
Tian, Hui; Fan, Siteng; Zhang, Lei; Yan, Limei
2018cosp...42E1404H Altcode:
As a coronal mass ejection (CME) passes, the flank and wake regions are
typically strongly disturbed. Various instruments, including the Large
Angle and Spectroscopic Coronagraph (LASCO), the Atmospheric Imaging
Assembly (AIA), and the Coronal Multi-channel Polarimeter (CoMP),
observed a CME close to the east limb on 26 October 2013.A hot (∼10
MK) rising blob was detected on the east limb, with an initial ejection
flow speed of ∼330 km/s. The magnetic structures on both sides and
in the wake of the CME were strongly distorted, showing initiation
of turbulent motions with Doppler-shift oscillations enhanced from
∼ ±3 km/s to ∼ ±15 km/s and effective thermal velocities from
∼30 km/s to ∼60 km/s, according to the CoMP observations at the
Fe XIII line. The CoMP Doppler-shift maps suggest that the turbulence
behaved differently at various heights; it showed clear wave-like
torsional oscillations at lower altitudes, which are interpreted as the
anti-phase oscillation of an alternating red/blue Doppler shift across
the strands at the flank. The turbulence seems to appear differently in
the channels of different temperatures. Its turnover time was ∼1000
seconds for the Fe 171 Å channel, while it was ∼500 seconds for the
Fe 193 Å channel. Mainly horizontal swaying rotations were observed in
the Fe 171 Å channel, while more vertical vortices were seen in the
Fe 193 Å channel. The differential-emission-measure profiles in the
flank and wake regions have two components that evolve differently:
the cool component decreased over time, evidently indicating a
drop-out of cool materials due to ejection, while the hot component
increased dramatically,probably because of the heating process, which
is suspected to be a result of magnetic reconnection and turbulence
dissipation. These results suggest a new turbulence-heating scenario
of the solar corona and solar wind.
---------------------------------------------------------
Title: A Space Coronal Magnetometry Mission
Authors: Lin, Haosheng; Gibson, Sarah; Savage, Sabrina; Tomczyk,
Steven; Downs, Cooper; Rachmeler, Laurel; Kramar, Maxim; Habbal, Shadia
2018cosp...42E2020L Altcode:
Direct measurement of the polarized spectra of forbidden coronal
emission lines (CELs) is the most powerful tool for the study of
the solar coronal magnetic fields. Due to its low optical density,
simultaneous multi-sight-lines observations of the corona from space
are needed for tomographic inversion to disentangle the 3D structure of
the solar corona. This presentation will describe the mission concept
and instrument design of a future space coronal magnetometry mission,
consists of many clusters of small spacecraft in near-sun heliocentric
orbits to observe the sun to enable tomographic determination of
the 3D magnetic and thermodynamic structures of the corona. The
spacecraft will be equipped with a wide field, super achromatic lens
coronagraph equipped with two 100-slit, 4-channel spectropolarimeters
optimized for measurement of the polarized CEL spectra from space. This
instrument is tentatively named 'mxCSM'- the massively-multiplexed
Coronal SpectroMagnetometer. A prototype mxCSM is currently under
construction with funding from a 2017 National Science Foundation
Major Research Instrument program grant. This space coronal space
magnetometry mission will advance our knowledge of the corona and the
physics of energetic coronal eruptions, and ultimately enable accurate
space weather forecast.
---------------------------------------------------------
Title: Experimental testing of scattering polarization models
Authors: Li, Wenxian; Casini, Roberto; Tomczyk, Steven; Landi
Degl'Innocenti, Egidio; Marsell, Brandan
2018AAS...23212305L Altcode:
We realized a laboratory experiment to study the polarization of the Na
I doublet at 589.3 nm, in the presence of a magnetic field. The purpose
of the experiment is to test the theory of scattering polarization for
illumination conditions typical of astrophysical plasmas. This work
was stimulated by solar observations of the Na I doublet that have
proven particularly challenging to reproduce with current models of
polarized line formation, even casting doubts on our very understanding
of the physics of scattering polarization on the Sun. The experiment
has confirmed the fundamental correctness of the current theory, and
demonstrated that the "enigmatic” polarization of those observations
is exclusively of solar origin.
---------------------------------------------------------
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. <P />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. <P />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
R<SUB>sun</SUB> 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: Turbulence and Heating in the Flank and Wake Regions of a
Coronal Mass Ejection
Authors: Fan, Siteng; He, Jiansen; Yan, Limei; Tomczyk, Steven; Tian,
Hui; Song, Hongqiang; Wang, Linghua; Zhang, Lei
2018SoPh..293....6F Altcode:
As a coronal mass ejection (CME) passes, the flank and wake regions are
typically strongly disturbed. Various instruments, including the Large
Angle and Spectroscopic Coronagraph (LASCO), the Atmospheric Imaging
Assembly (AIA), and the Coronal Multi-channel Polarimeter (CoMP),
observed a CME close to the east limb on 26 October 2013. A hot (≈10
MK) rising blob was detected on the east limb, with an initial ejection
flow speed of ≈330 kms−<SUP>1</SUP>. The magnetic structures
on both sides and in the wake of the CME were strongly distorted,
showing initiation of turbulent motions with Doppler-shift oscillations
enhanced from ≈±3 kms−<SUP>1</SUP> to ≈±15 kms−<SUP>1</SUP>
and effective thermal velocities from ≈30 kms−<SUP>1</SUP> to ≈60
kms−<SUP>1</SUP>, according to the CoMP observations at the Fe XIII
line. The CoMP Doppler-shift maps suggest that the turbulence behaved
differently at various heights; it showed clear wave-like torsional
oscillations at lower altitudes, which are interpreted as the antiphase
oscillation of an alternating red/blue Doppler shift across the strands
at the flank. The turbulence seems to appear differently in the channels
of different temperatures. Its turnover time was ≈1000 seconds for
the Fe 171 Å channel, while it was ≈500 seconds for the Fe 193 Å
channel. Mainly horizontal swaying rotations were observed in the Fe
171 Å channel, while more vertical vortices were seen in the Fe 193
Å channel. The differential-emission-measure profiles in the flank
and wake regions have two components that evolve differently: the
cool component decreased over time, evidently indicating a drop-out
of cool materials due to ejection, while the hot component increased
dramatically, probably because of the heating process, which is
suspected to be a result of magnetic reconnection and turbulence
dissipation. These results suggest a new turbulence-heating scenario
of the solar corona and solar wind.
---------------------------------------------------------
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: Multi-wavelength observations of the solar atmosphere from
the August 21, 2017 total solar eclipse
Authors: Tomczyk, S.; Boll, A.; Bryans, P.; Burkepile, J.; Casini,
R.; DeLuca, E.; Gibson, K. L.; Judge, P. G.; McIntosh, S. W.; Samra,
J.; Sewell, S. D.
2017AGUFMSH24A..04T Altcode:
We will conduct three experiments at the August 21, 2017 total
solar eclipse that we call the Rosetta Stone experiments. First,
we will obtain narrow-bandpass images at infrared wavelengths of the
magnetically sensitive coronal emission lines of Fe IX 2855 nm, Mg VIII
3028 nm and Si IX 3935 nm with a FLIR thermal imager. Information on the
brightness of these lines is important for identifying the optimal lines
for coronal magnetometry. These images will also serve as context images
for the airborne AirSpec IR coronal spectroscopy experiment (Samra et
al). Second, we will obtain linear polarization images of the visible
emission lines of Fe X 637 nm and Fe XI 789 nm as well as the continuum
polarization near 735 nm. These will be obtained with a novel detector
with an integral array of linear micro-polarizers oriented at four
different angles that enable polarization images without the need for
liquid crystals or rotating elements. These measurements will provide
information on the orientation of magnetic fields in the corona and
serve to demonstrate the new detector technology. Lastly, we will obtain
high cadence spectra as the moon covers and uncovers the chromosphere
immediately after 2nd contact and before third contact. This so-called
flash spectrum will be used to obtain information about chromospheric
structure at a spatial resolution higher than is possible by other
means. In this talk, we will describe the instrumentation used in these
experiments and present initial results obtained with them. This work
is supported by a grant from NASA, through NSF base funding of HAO/NCAR
and by generous loans of equipment from our corporate partners, FLIR,
4D Technologies and Avantes.
---------------------------------------------------------
Title: Polarization Observations of the Total Solar Eclipse of August
21, 2017
Authors: Burkepile, J.; Boll, A.; Casini, R.; de Toma, G.; Elmore,
D. F.; Gibson, K. L.; Judge, P. G.; Mitchell, A. M.; Penn, M.; Sewell,
S. D.; Tomczyk, S.; Yanamandra-Fisher, P. A.
2017AGUFMSH13B2477B Altcode:
A total solar eclipse offers ideal sky conditions for viewing the
solar corona. Light from the corona is composed of three components:
the E-corona, made up of spectral emission lines produced by ionized
elements in the corona; the K-corona, produced by photospheric light
that is Thomson scattered by coronal electrons; and the F-corona,
produced by sunlight scattered from dust particles in the near
Sun environment and in interplanetary space. Polarized white light
observations of the corona provide a way of isolating the K-corona to
determine its structure, brightness, and density. This work focuses
on broadband white light polarization observations of the corona
during the upcoming solar eclipse from three different instruments. We
compare coronal polarization brightness observations of the August 21,
2017 total solar eclipse from the NCAR/High Altitude Observatory (HAO)
Rosetta Stone experiment using the 4-D Technology PolarCam camera with
the two Citizen PACA_CATE17Pol telescopes that will acquire linear
polarization observations of the eclipse and the NCAR/HAO K-Cor white
light coronagraph observations from the Mauna Loa Solar Observatory in
Hawaii. This comparison includes a discussion of the cross-calibration
of the different instruments and reports the results of the coronal
polarization brightness and electron density of the corona. These
observations will be compared with results from previous coronal
measurements taken at different phases of the solar cycle. In addition,
we report on the performance of the three different polarimeters. The
4-D PolarCam uses a linear polarizer array, PACA_CATE17Pol uses
a nematic liquid crystal retarder in a single beam configuration
and K-Cor uses a pair of ferroelectric liquid crystal retarders in
a dual-beam configuration. The use of the 4-D PolarCam camera in the
Rosetta Stone experiment is to demonstrate the technology for acquiring
high cadence polarization measurements. The Rosetta Stone experiment
is funded through the NASA award NNH16ZDA001N-ISE. The Citizen Science
approach to measuring the polarized solar corona during the eclipse
is funded through NASA award NNX17AH76G. The NCAR Mauna Loa Solar
Observatory is funded by the National Science Foundation.
---------------------------------------------------------
Title: Measuring Solar Coronal Magnetism during the Total Solar
Eclipse of 2017
Authors: Gibson, K. L.; Tomczyk, S.
2017AGUFMSH13B2478G Altcode:
The total solar eclipse on August 21, 2017 provided a notable
opportunity to measure the solar corona at specific emission wavelengths
to gain information about coronal magnetic fields. Solar magnetic
fields are intimately related to the generation of space weather and
its effects on the earth, and the infrared imaging and polarization
information collected on coronal emission lines here will enhance
the scientific value of several other ongoing experiments, as well
as benefit the astrophysics and upper atmosphere communities. Coronal
measurements were collected during the 2 minute and 24 second totality
period from Casper Mountain, WY. Computer-controlled telescopes
automatically inserted four different narrow band pass filters to
capture images in the visible range on a 4D PolCam, and in the infrared
range on the FLIR 8501c camera. Each band pass filter selects a specific
wavelength range that corresponds to a known coronal emission line
possessing magnetic sensitivity. The 4D PolCam incorporated a novel
grid of linear polarizers precisely aligned with the micron scale
pixels. This allowed for direct measurement of the degree of linear
polarization in a very small instrument with no external moving parts
as is typically required. The FLIR offers short exposure times to
freeze motion and output accurate thermal measurements. This allowed
a new observation of the sun's corona using thermo infrared technology.
---------------------------------------------------------
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: 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.
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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: Magnetic Nulls and Super-radial Expansion in the Solar Corona
Authors: Gibson, Sarah E.; Dalmasse, Kevin; Rachmeler, Laurel A.;
De Rosa, Marc L.; Tomczyk, Steven; de Toma, Giuliana; Burkepile,
Joan; Galloy, Michael
2017ApJ...840L..13G Altcode: 2017arXiv170407470G
Magnetic fields in the Sun’s outer atmosphere—the corona—control
both solar-wind acceleration and the dynamics of solar eruptions. We
present the first clear observational evidence of coronal magnetic
nulls in off-limb linearly polarized observations of pseudostreamers,
taken by the Coronal Multichannel Polarimeter (CoMP) telescope. These
nulls represent regions where magnetic reconnection is likely to act
as a catalyst for solar activity. CoMP linear-polarization observations
also provide an independent, coronal proxy for magnetic expansion into
the solar wind, a quantity often used to parameterize and predict the
solar wind speed at Earth. We introduce a new method for explicitly
calculating expansion factors from CoMP coronal linear-polarization
observations, which does not require photospheric extrapolations. We
conclude that linearly polarized light is a powerful new diagnostic
of critical coronal magnetic topologies and the expanding magnetic
flux tubes that channel the solar wind.
---------------------------------------------------------
Title: 3D Global Coronal Density, Temperature, and Vector Magnetic
Field Derived from Coronal Observation.
Authors: Kramar, M.; Lin, H.; Airapetian, V.; Tomczyk, S.
2016AGUFMSH43A2558K Altcode:
Solar coronal magnetic fields play a key role in the energetics and
dynamics of coronal heating, solar flares, coronal mass ejections (CME),
filament eruptions, and determine space weather processes. Therefore,
one of the central problems of solar physics is to measure the
magnetic fields in the solar corona.The main techniques that are
currently used to deduce the global magnetic structure of the solar
corona include potential field, nonlinear force-free field (NLFFF),
and magnetohydrodynamic (MHD) models. These methods are based on
boundary conditions of the solar photospheric magnetic field that
are derived directly from photospheric magnetograms. All of these
methods are essentially extrapolation methods based on inner boundary
conditions taken at the photosphere. However, the magnetic field at the
photosphere and lower chromosphere is far from potential or force-free,
because of the dominance of the plasma pressure there.We will present
3D reconstruction of the global coronal electron density, temperature
during periods of minimum and maximum of solar activity cycle and
derived from coronal STEREO/COR1 and EUVI observations. We find that
the magnetic field configuration during maximum of solar activity
(CR 2131) has a tendency to become radially open at heliocentric
distances below 2.5 Rsun while during the solar minimum (CR 2066) they
tend to open at higher distances.Moreover, the obtained 3D density and
temperature has been used as additional input for recently developed
vector tomography method to reconstruct the coronal vector magnetic
field based on polarimetric observation of magnetically sensitive Fe
XIII ion emission by Coronal Magnetic Polarimeter (CoMP). We validated
the vector tomography inverted coronal magnetic fields with those
constructed by MHD simulation based on observed photospheric magnetic
fields as well as with the STEREO/EUVI 195 image and with the global
3D coronal electron density structure obtained by tomography based on
STEREO/COR1 data.
---------------------------------------------------------
Title: Exploring Coronal Dynamics: A Next Generation Solar Physics
Mission white paper
Authors: Morton, R. J.; Scullion, E.; Bloomfield, D. S.; McLaughlin,
J. A.; Regnier, S.; McIntosh, S. W.; Tomczyk, S.; Young, P.
2016arXiv161106149M Altcode:
Determining the mechanisms responsible for the heating of the
coronal plasma and maintaining and accelerating the solar wind
are long standing goals in solar physics. There is a clear need to
constrain the energy, mass and momentum flux through the solar corona
and advance our knowledge of the physical process contributing to
these fluxes. Furthermore, the accurate forecasting of Space Weather
conditions at the near-Earth environment and, more generally, the
plasma conditions of the solar wind throughout the heliosphere, require
detailed knowledge of these fluxes in the near-Sun corona. Here we
present a short case for a space-based imaging-spectrometer coronagraph,
which will have the ability to provide synoptic information on the
coronal environment and provide strict constraints on the mass, energy,
and momentum flux through the corona. The instrument would ideally
achieve cadences of $\sim10$~s, spatial resolution of 1" and observe the
corona out to 2~$R_{\sun}$. Such an instrument will enable significant
progress in our understanding of MHD waves throughout complex plasmas,
as well as potentially providing routine data products to aid Space
Weather forecasting.
---------------------------------------------------------
Title: A Global View of Velocity Fluctuations in the Corona below
1.3 R <SUB>⊙</SUB> with CoMP
Authors: Morton, R. J.; Tomczyk, S.; Pinto, R. F.
2016ApJ...828...89M Altcode: 2016arXiv160801831M
The Coronal Multi-channel Polarimeter (CoMP) has previously demonstrated
the presence of Doppler velocity fluctuations in the solar corona. The
observed fluctuations are thought to be transverse waves, I.e., highly
incompressible motions whose restoring force is dominated by the
magnetic tension, some of which demonstrate clear periodicity. We aim
to exploit CoMP’s ability to provide high cadence observations of the
off-limb corona to investigate the properties of velocity fluctuations
in a range of coronal features, providing insight into how (whether)
the properties of the waves are influenced by the varying magnetic
topology in active regions, quiet Sun and open field regions. An
analysis of Doppler velocity time-series of the solar corona from
the 10747 Å Iron xiii line is performed, determining the velocity
power spectrum and using it as a tool to probe wave behavior. Further,
the average phase speed and density for each region are estimated and
used to compute the spectra for energy density and energy flux. In
addition, we assess the noise levels associated with the CoMP data,
deriving analytic formulae for the uncertainty on Doppler velocity
measurements and providing a comparison by estimating the noise
from the data. It is found that the entire corona is replete with
transverse wave behavior. The corresponding power spectra indicate
that the observed velocity fluctuations are predominately generated
by stochastic processes, with the spectral slope of the power varying
between the different magnetic regions. Most strikingly, all power
spectra reveal the presence of enhanced power occurring at ∼3 mHz,
potentially implying that the excitation of coronal transverse waves
by p-modes is a global phenomenon.
---------------------------------------------------------
Title: Coronal plasma diagnostics from ground-based observations
Authors: Landi, E.; Habbal, S. R.; Tomczyk, S.
2016JGRA..121.8237L Altcode:
In this paper we discuss the potential of ground-based visible
observations of the solar corona to address the key open problems in
the physics of the solar atmosphere and of solar activity. We first
compare the diagnostic potential of visible observations with those of
high-resolution spectrometers and narrowband imagers working in the
EUV and X-ray wavelength ranges. We then review the main diagnostic
techniques (and introduce a few new ones) that can be applied to
line and continuum emission in the solar atmosphere, and the physical
problems that they enable us to address. Finally, we briefly review the
main features of ground-based coronographic instrumentation currently
being developed and planned.
---------------------------------------------------------
Title: Scientific objectives and capabilities of the Coronal Solar
Magnetism Observatory
Authors: Tomczyk, S.; Landi, E.; Burkepile, J. T.; Casini, R.; DeLuca,
E. E.; Fan, Y.; Gibson, S. E.; Lin, H.; McIntosh, S. W.; Solomon,
S. C.; Toma, G.; Wijn, A. G.; Zhang, J.
2016JGRA..121.7470T Altcode:
Magnetic influences increase in importance in the solar atmosphere
from the photosphere out into the corona, yet our ability to routinely
measure magnetic fields in the outer solar atmosphere is lacking. We
describe the scientific objectives and capabilities of the COronal Solar
Magnetism Observatory (COSMO), a proposed synoptic facility designed
to measure magnetic fields and plasma properties in the large-scale
solar atmosphere. COSMO comprises a suite of three instruments chosen
to enable the study of the solar atmosphere as a coupled system: (1)
a coronagraph with a 1.5 m aperture to measure the magnetic field,
temperature, density, and dynamics of the corona; (2) an instrument
for diagnostics of chromospheric and prominence magnetic fields and
plasma properties; and (3) a white light K-coronagraph to measure
the density structure and dynamics of the corona and coronal mass
ejections. COSMO will provide a unique combination of magnetic field,
density, temperature, and velocity observations in the corona and
chromosphere that have the potential to transform our understanding
of fundamental physical processes in the solar atmosphere and their
role in the origins of solar variability and space weather.
---------------------------------------------------------
Title: Systems engineering overview and concept of operations of
the COronal Solar Magnetism Observatory (COSMO)
Authors: Oakley, P. H. H.; Tomczyk, S.; Sewell, S.; Gallagher, D.;
Larson, B.
2016SPIE.9911E..2IO Altcode:
The COronal Solar Magnetism Observatory (COSMO) is a proposed facility
with unique capabilities for magnetic field measurements in the solar
atmosphere and corona to increase our understanding of solar physics and
space weather. The observatory underwent a preliminary design review
(PDR) in 2015. This paper summarizes the systems engineering plan
for this facility as well as a preliminary overview of the concept of
operations. In particular we detail the flow of science requirements
to engineering requirements, and discuss an overview of requirements
management, documentation management, interface control and overall
verification and compliance processes. Operationally, we discuss the
categories of operational modes, as well as an overview of a daily
operational cycle.
---------------------------------------------------------
Title: Development of a tunable filter for coronal polarimetry
Authors: Tomczyk, S.; Mathew, S. K.; Gallagher, D.
2016JGRA..121.6184T Altcode:
Measuring magnetic fields in the solar corona is crucial to
understanding and predicting the Sun's generation of space weather
that affects communications, GPS systems, space flight, and power
transmission. The Coronal Solar Magnetism Observatory Large Coronagraph
(COSMO LC) is a proposed 1.5 m aperture coronagraph designed to
synoptically observe magnetic fields and plasma properties in the
large-scale corona to improve our understanding of solar processes
that cause space weather. The LC will observe coronal emission lines
over the wavelength range from 500 to 1100 nm with a field of view
of 1° and a spatial resolution of 2 arcsec. A spectral resolution
greater than 8000 over the wavelength range is needed to resolve
the polarization signatures of magnetic fields in the emission line
profiles. The aperture and field of view of the LC set an étendue
requirement of 1.39 m<SUP>2</SUP> deg<SUP>2</SUP> for the postfocus
instrumentation. We find that a tunable wide-field birefringent filter
using Lithium Niobate crystals can meet the étendue and spectral
resolution requirements for the LC spectrometer. We have tested a
number of commercially available crystals and verify that crystals of
the required size and birefringence uniformity are available. We also
evaluate electro-optical tuning of a Lithium Niobate birefringent filter
by the application of high voltage. This tunable filter represents a
key enabling technology for the COSMO LC.
---------------------------------------------------------
Title: The COSMO coronagraph optical design and stray light analysis
Authors: Gallagher, Dennis; Wu, Zhen; Larson, Brandon; Nelson, Peter
G.; Oakley, Phil; Sewell, Scott; Tomczyk, Steven
2016SPIE.9906E..54G Altcode:
The Coronal Solar Magnetism Observatory Large Coronagraph (COSMO-LC)
is a 1.5 meter Lyot coronagraph dedicated to measuring magnetic
fields and plasma properties in the solar corona. The COSMO-LC will
be able to observe coronal emissions lines from 530-1100 nm using a
filtergraph instrument. COSMO-LC will have a 1 degree field of view
to observe the full solar corona out to 1 solar radius beyond the limb
of the sun. This presented challenges due to the large Etendue of the
system. The COSMO-LC spatial resolution is 2 arc-seconds per pixel (4k
X 4k). The most critical part of the coronagraph is the objective lens
that is exposed to direct sunlight that is five orders of magnitude
brighter than the corona. Therefore, it is key to the operation of
a coronagraph that the objective lens (O1) scatter as little light
as possible, on order a few parts per million. The selection of the
material and the polish applied to the O1 are critical in reducing
scattered light. In this paper we discuss the design of the COSMO-LC
and the detailed design of the O1 and other key parts of the COSMO-LC
that keep stray light to a minimum. The result is an instrument with
stray light below 5 millionths the brightness of the sun 50 arc-seconds
from the sun. The COSMO-LC has just had a Preliminary Design Review
(PDR) and the PDR design is presented.
---------------------------------------------------------
Title: What’s New at the Mauna Loa Solar Observatory
Authors: Burkepile, Joan; de Toma, Giuliana; Galloy, Michael; Kolinski,
Don; Berkey, Ben; Stueben, Allen; Tomczyk, Steven; De Wijn, Alfred;
Casini, Roberto; Card, Greg; Larson, Brandon; Stanger, Andrew; Oakley,
Phil; Gallagher, Dennis; Waters, Lisa; Rose, Greg; Sewell, Scott
2016SPD....47.0801B Altcode:
The Mauna Loa Solar Observatory (MLSO) is located at 3440 meters
on the island of Hawaii. The site provides the dark, clear skies
required for observing the solar corona. The National Center for
Atmosphere Research (NCAR) High Altitude Observatory (HAO) operates two
coronagraphs at the site: the Coronal Multi-Channel Polarimeter (CoMP)
and the COSMO K-Coronagraph (K-Cor). CoMP is designed to study coronal
magnetic fields by observing full Stokes polarimetry of two forbidden
emission lines of FeXIII at 1074.7 and 1079.8 nm. CoMP also observes
active and erupting prominences over the solar limb in neutral Helium
emission at 1083.nm. The K-Cor is designed to study the onset and early
evolution of coronal mass ejections (CMEs). It is the only white light
coronagraph to routinely view the low corona down to 1.05 solar radii
in order to capture the formation of CMEs. Information is provided on
new Helium data products of active and erupting prominences observed
by the CoMP instrument as well as results from the K-Cor observations
of CMEs. Information on current and upcoming upgrades to the MLSO
facility, instrument hardware, and calibrations are reported along
with an accounting of new data products, tools and services from the
MLSO website.
---------------------------------------------------------
Title: The CoMP-S Instrument at the Lomnický Peak Observatory:
Status Report
Authors: Kučera, A.; Ambróz, J.; Gömöry, P.; Habaj, P.; Kavka,
J.; Kozák, M.; Schwartz, P.; Rybák, J.; Tomczyk, S.; Sewell, S.;
Aumiller, P.; Summers, R.; Watt, A.
2016ASPC..504..321K Altcode:
The Coronal Multi-channel Polarimeter for Slovakia (CoMP-S) has
been installed at the high-altitude Lomnicky Peak Observatory of the
Astronomical Institute of SAS (2633 m a.s.l.) in 2011. The instrument
was designed and manufactured by HAO/NCAR (Boulder, USA) with a
tunable Lyot filter and polarimeter for visible and near IR spectral
regions. This instrument is proposed for coronagraphic observations of
magnetic and velocity fields in the solar corona and in prominences. A
fundamental upgrade of this instrument has been prepared with pair
of cameras sensitive in the near IR spectral region in a new camera
module. This upgrade is being incorporated to the instrument in course
of the year 2014. In this contribution the technical parameters of the
final configuration of the CoMP-S instrument containing four cameras,
covering both visible and near IR spectral regions, are described. We
also present a potential of the CoMP-S instrument for coronagraphic
spectro-polarimetric observations of the solar corona and prominences
with a capability for sequential measurements of the spectral profiles
of all prominent emission lines in spectral region from 500 to 1100 nm.
---------------------------------------------------------
Title: Direct Observation of Solar Coronal Magnetic Fields by Vector
Tomography of the Coronal Emission Line Polarizations
Authors: Kramar, M.; Lin, H.; Tomczyk, S.
2016ApJ...819L..36K Altcode: 2015arXiv150207200K
We present the first direct “observation” of the global-scale,
3D coronal magnetic fields of Carrington Rotation (CR) Cycle 2112
using vector tomographic inversion techniques. The vector tomographic
inversion uses measurements of the Fe xiii 10747 Å Hanle effect
polarization signals by the Coronal Multichannel Polarimeter (CoMP)
and 3D coronal density and temperature derived from scalar tomographic
inversion of Solar Terrestrial Relations Observatory (STEREO)/Extreme
Ultraviolet Imager (EUVI) coronal emission lines (CELs) intensity
images as inputs to derive a coronal magnetic field model that best
reproduces the observed polarization signals. While independent
verifications of the vector tomography results cannot be performed,
we compared the tomography inverted coronal magnetic fields with those
constructed by magnetohydrodynamic (MHD) simulations based on observed
photospheric magnetic fields of CR 2112 and 2113. We found that the
MHD model for CR 2112 is qualitatively consistent with the tomography
inverted result for most of the reconstruction domain except for several
regions. Particularly, for one of the most noticeable regions, we found
that the MHD simulation for CR 2113 predicted a model that more closely
resembles the vector tomography inverted magnetic fields. In another
case, our tomographic reconstruction predicted an open magnetic field at
a region where a coronal hole can be seen directly from a STEREO-B/EUVI
image. We discuss the utilities and limitations of the tomographic
inversion technique, and present ideas for future developments.
---------------------------------------------------------
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Ko, Yuan-Kuen; Moses, John; Laming, John; Strachan, Leonard;
Tun Beltran, Samuel; Tomczyk, Steven; Gibson, Sarah; Auchere, Frederic;
Casini, Roberto; Fineschi, Silvano; Knoelker, Michael; Korendyke,
Clarence; McIntosh, Scott; Romoli, Marco; Rybak, Jan; Socker, Dennis;
Vourlidas, Angelos; Wu, Qian
2016FrASS...3....1K Altcode:
Comprehensive measurements of magnetic fields in the solar corona have
a long history as an important scientific goal. Besides being crucial
to understanding coronal structures and the Sun’s generation of space
weather, direct measurements of their strength and direction are also
crucial steps in understanding observed wave motions. In this regard,
the remote sensing instrumentation used to make coronal magnetic field
measurements is well suited to measuring the Doppler signature of waves
in the solar structures. In this paper, we describe the design and
scientific values of the Waves and Magnetism in the Solar Atmosphere
(WAMIS) investigation. WAMIS, taking advantage of greatly improved
infrared filters and detectors, forward models, advanced diagnostic
tools and inversion codes, is a long-duration high-altitude balloon
payload designed to obtain a breakthrough in the measurement of
coronal magnetic fields and in advancing the understanding of the
interaction of these fields with space plasmas. It consists of a 20 cm
aperture coronagraph with a visible-IR spectro-polarimeter focal plane
assembly. The balloon altitude would provide minimum sky background and
atmospheric scattering at the wavelengths in which these observations
are made. It would also enable continuous measurements of the strength
and direction of coronal magnetic fields without interruptions from
the day-night cycle and weather. These measurements will be made
over a large field-of-view allowing one to distinguish the magnetic
signatures of different coronal structures, and at the spatial and
temporal resolutions required to address outstanding problems in
coronal physics. Additionally, WAMIS could obtain near simultaneous
observations of the electron scattered K-corona for context and to
obtain the electron density. These comprehensive observations are not
provided by any current single ground-based or space observatory. The
fundamental advancements achieved by the near-space observations of
WAMIS on coronal field would point the way for future ground based
and orbital instrumentation.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory
Authors: Tomczyk, S.; Landi, E.; Zhang, J.; Lin, H.; DeLuca, E. E.
2015AGUFMSH43B2460T Altcode:
Measurements of coronal and chromospheric magnetic fields are
arguably the most important observables required for advances in
our understanding of the processes responsible for coronal heating,
coronal dynamics and the generation of space weather that affects
communications, GPS systems, space flight, and power transmission. The
Coronal Solar Magnetism Observatory (COSMO) is a proposed ground-based
suite of instruments designed for routine study of coronal and
chromospheric magnetic fields and their environment, and to understand
the formation of coronal mass ejections (CME) and their relation to
other forms of solar activity. This new facility will be operated by
the High Altitude Observatory of the National Center for Atmospheric
Research (HAO/NCAR) with partners at the University of Michigan, the
University of Hawaii and George Mason University in support of the
solar and heliospheric community. It will replace the current NCAR
Mauna Loa Solar Observatory (http://mlso.hao.ucar.edu). COSMO will
enhance the value of existing and new observatories on the ground and
in space by providing unique and crucial observations of the global
coronal and chromospheric magnetic field and its evolution. The design
and current status of the COSMO will be reviewed.
---------------------------------------------------------
Title: Coronal plasma diagnostics from eclipse observations
Authors: Landi, E.; Habbal, S. R.; Tomczyk, S.
2015AGUFMSH51C2456L Altcode:
In this talk we will discuss the diagnostic potential of observationsof
visible spectral lines formed in the extended solar corona that
canbe obtained during eclipses. We will discuss the possible
diagnosticapplications of visible eclipse observations to measure the
physicalparameters of the extended corona, to understand solar wind
origin andacceleration, and to determine the evolution of Coronal
Mass Ejectionsduring onset.We will first review the mechanisms of
formation of spectral lineintensities, we will then illustrate their
diagnostic applications,and show some results from recent eclipse
observations. We will alsoreview the spectral lines that are most
likely to be observed inthe extended solar corona during the upcoming
2017 eclipse in thecontinental United States.
---------------------------------------------------------
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Strachan, L.; Ko, Y. -K.; Moses, J. D.; Laming, J. M.;
Auchere, F.; Casini, R.; Fineschi, S.; Gibson, S.; Knoelker, M.;
Korendyke, C.; Mcintosh, S.; Romoli, M.; Rybak, J.; Socker, D.;
Tomczyk, S.; Vourlidas, A.; Wu, Q.
2015IAUS..305..121S Altcode:
Magnetic fields in the solar atmosphere provide the energy for most
varieties of solar activity, including high-energy electromagnetic
radiation, solar energetic particles, flares, and coronal mass
ejections, as well as powering the solar wind. Despite the fundamental
role of magnetic fields in solar and heliospheric physics, there
exist only very limited measurements of the field above the base of
the corona. What is needed are direct measurements of not only the
strength and orientation of the magnetic field but also the signatures
of wave motions in order to better understand coronal structure, solar
activity, and the role of MHD waves in heating and accelerating the
solar wind. Fortunately, the remote sensing instrumentation used to make
magnetic field measurements is also well suited to measure the Doppler
signature of waves in the solar structures. We present here a mission
concept for the Waves And Magnetism In the Solar Atmosphere (WAMIS)
experiment which is proposed for a NASA long-duration balloon flight.
---------------------------------------------------------
Title: 3D Observation of the Global Coronal Magnetic Field by Vector
Tomography using the Coronal Emission Linear Polarization Data.
Authors: Kramar, Maxim; Lin, Haosheng; Tomczyk, Steven
2015IAUGA..2257404K Altcode:
Measurement of the coronal magnetic field is a crucial ingredient
in understanding the nature of solar coronal phenomena at all
scales. However, due to the low density and opacity of the solar
atmosphere, the coronal emission measurements are result of a
line-of-sight (LOS) integration through a nonuniform temperature,
density and magnetic field distribution. Therefore, except in a few
special cases, a direct inference of the 3D coronal magnetic field
structure from polarization data is in general not possible. Tomography
methods allow to resolve the LOS problem.We will present the
global-scale, 3D coronal vector magnetic fields obtained by a vector
tomographic inversion technique.The Vector tomographic inversion uses
measurements of the Fe XIII 10747 A Hanle effect linear polarization
signals by the Coronal Multichannel Polarimeter (CoMP) as inputs to
derive a coronal magnetic field model that best reproduces the observed
polarization signals. The 3D electron density and temperature, needed
as additional input, have been reconstructed by scalar field tomography
method based on STEREO/EUVI data. We will present the 3D coronal vector
magnetic field, electron density and temperature resulted from these
inversions.While independent verifications of the vector tomography
results cannot be performed, we compared the tomography inverted coronal
magnetic fields with those constructed by MagnetoHydroDynamic (MHD)
simulation based on observed photospheric magnetic fields and with 3D
coronal density structures obtained by scalar field tomography based
on coronal observations. We will discuss the utilities and limitations
of the inversion technique, and present ideas for future developments.
---------------------------------------------------------
Title: Dual instrument for Flare and CME onset observations -
Double solar Coronagraph with Solar Chromospheric Detector and
Coronal Multi-channel Polarimeter at Lomnicky stit Observatory
Authors: Kucera, Ales; Tomczyk, Steven; Rybak, Jan; Sewell, Scott;
Gomory, Peter; Schwartz, Pavol; Ambroz, Jaroslav; Kozak, Matus
2015IAUGA..2246687K Altcode:
We report on unique dual instrument developed for simultaneous
measurements of velocity and magnetic fields in the solar chromosphere
and corona. We describe the technical parameters and capability of
the Coronal Multi-channel Polarimeter (CoMP-S) and Solar Chromospheric
detector (SCD) mounted at the Double solar coronagraph at Lomnicky Stit
Observatory and working simultaneously with strictly parallel pointing
of both coronagraphs. The CoMP-S is 2D spectropolarimeter designed
for observations of VIS and near-IR emission lines of prominences
and corona with operating spectral range: 500 - 1100 nm, sequential
measurement of several VIS and near-IR lines. Its field of view is
14 arcmin x 11 arcmin. It consists of 4-stage calcite Lyot filter
followed by the ferro-liquid crystal polarizer and four cameras (2
visible, 2 infrared). The capability is to deliver 2D full Stokes I,
Q, U, V, using registration with 2 IR cameras (line + background) and
2 VIS cameras (line + background) SCD is a single beam instrument to
observe bright chromosphere. It is a combination of tunable filter and
polarimeter. Spectral resolution of the SCD ranges from 0.046 nm for
observations of the HeI 1083 nm line up to to 25 pm is for observation
of the HeI 587.6 nm line. The birefringent filter of the SCD has high
spectral resolution, as well as spatial resolution (1.7 arcseconds)
and temporal resolution (10 seconds) First results are also reported
and discussed.
---------------------------------------------------------
Title: Investigating Alfvénic wave propagation in coronal open-field
regions
Authors: Morton, R. J.; Tomczyk, S.; Pinto, R.
2015NatCo...6.7813M Altcode: 2015NatCo...6E7813M
The physical mechanisms behind accelerating solar and stellar winds are
a long-standing astrophysical mystery, although recent breakthroughs
have come from models invoking the turbulent dissipation of Alfvén
waves. The existence of Alfvén waves far from the Sun has been known
since the 1970s, and recently the presence of ubiquitous Alfvénic
waves throughout the solar atmosphere has been confirmed. However,
the presence of atmospheric Alfvénic waves does not, alone,
provide sufficient support for wave-based models; the existence of
counter-propagating Alfvénic waves is crucial for the development of
turbulence. Here, we demonstrate that counter-propagating Alfvénic
waves exist in open coronal magnetic fields and reveal key observational
insights into the details of their generation, reflection in the
upper atmosphere and outward propagation into the solar wind. The
results enhance our knowledge of Alfvénic wave propagation in the
solar atmosphere, providing support and constraints for some of the
recent Alfvén wave turbulence models.
---------------------------------------------------------
Title: The CoMP Instrument and Data Processing
Authors: Plowman, Joseph E.; de Toma, Giuliana; Tomczyk, Steven
2015TESS....130901P Altcode:
We present an overview of the Coronal Multichannel Polarimeter (CoMP)
coronagraph instrument, which observes infrared lines sensitive to the
magnetic field in the solar corona. The overview covers the general
properties of the instrument, its sensitivity to solar phenomena of
interest, and sources of error and uncertainty in its data. We also show
some updated results and processing of the data, which include improved
coalignment and updated calibration (flat-fielding, dark subtraction,
and polarization cross-talk). The ultimate goal of this processing is
more clearly resolving the linear polarization signal (especially of
the weaker 10798 Angstrom line) in the data and eventually resolving
the Stokes V signal as well.
---------------------------------------------------------
Title: 3D Coronal Magnetic Field Reconstruction Based on Infrared
Polarimetric Observations
Authors: Kramar, M.; Lin, H.; Tomczyk, S.
2014AGUFMSH13A4069K Altcode:
Measurement of the coronal magnetic field is a crucial ingredient in
understanding the nature of solar coronal phenomena at all scales. A
significant progress has been recently achieved here with deployment
of the Coronal Multichannel Polarimeter (CoMP) of the High Altitude
Observatory (HAO). The instrument provides polarization measurements of
Fe xiii 10747 A forbidden line emission. The observed polarization are
the result of a line-of-sight (LOS) integration through a nonuniform
temperature, density and magnetic field distribution. In order resolve
the LOS problem and utilize this type of data, the vector tomography
method has been developed for 3D reconstruction of the coronal magnetic
field. The 3D electron density and temperature, needed as additional
input, have been reconstructed by tomography method based on STEREO/EUVI
data. We will present the 3D coronal magnetic field and associated 3D
curl B, density, and temperature resulted from these inversions.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory (COSMO)
Authors: Tomczyk, S.; Landi, E.; Lin, H.; Zhang, J.
2014AGUFMSH53B4212T Altcode:
Measurements of coronal and chromospheric magnetic fields are arguably
the most important observables required in our understanding of the
emergence of magnetic flux into the solar atmosphere and the processes
responsible for the production of solar activity, coronal heating
and coronal dynamics. However, routine observations of the strength
and orientation of coronal and chromospheric magnetic fields are
not currently available. COSMO is a proposed ground-based suite of
instruments designed for routine study of coronal and chromospheric
magnetic fields and their environment. We will present an overview
of the COSMO and show recent progress in development of the COSMO
observatory.
---------------------------------------------------------
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Ko, Y. K.; Auchere, F.; Casini, R.; Fineschi, S.; Gibson,
S. E.; Knoelker, M.; Korendyke, C.; Laming, J. M.; Mcintosh, S. W.;
Moses, J. D.; Romoli, M.; Rybak, J.; Socker, D. G.; Strachan, L.;
Tomczyk, S.; Vourlidas, A.; Wu, Q.
2014AGUFMSH53B4221K Altcode:
Magnetic fields in the solar atmosphere provide the energy for most
varieties of solar activity, including high-energy electromagnetic
radiation, solar energetic particles, flares, and coronal mass
ejections, as well as powering the solar wind. Despite the fundamental
role of magnetic fields in solar and heliospheric physics, there
exists only very limited measurements of the field above the base of
the corona. What is needed are direct measurements of not only the
strength and orientation of the magnetic field but also the signatures
of wave motions in order to better understand coronal structure,
solar activity and the role of MHD waves in heating and accelerating
the solar wind. Fortunately, the remote sensing instrumentation used
to make magnetic field measurements is also well suited for measuring
the Doppler signature of waves in the solar structures. With this
in mind, we are proposing the WAMIS (Waves and Magnetism in the
Solar Atmosphere) investigation. WAMIS will take advantage of greatly
improved infrared (IR) detectors, forward models, advanced diagnostic
tools and inversion codes to obtain a breakthrough in the measurement
of coronal magnetic fields and in the understanding of the interaction
of these fields with space plasmas. This will be achieved with a high
altitude balloon borne payload consisting of a coronagraph with an IR
spectro-polarimeter focal plane assembly. The balloon platform provides
minimum atmospheric absorption and scattering at the IR wavelengths in
which these observations are made. Additionally, a NASA long duration
balloon flight mission from the Antarctic can achieve continuous
observations over most of a solar rotation, covering all of the key
time scales for the evolution of coronal magnetic fields. With these
improvements in key technologies along with experience gained from
current ground-based instrumentation, WAMIS will provide a low-cost
mission with a high technology readiness leve.
---------------------------------------------------------
Title: Turbulence and Heating in the Side and Wake Regions of Coronal
Mass Ejection in the Low Corona
Authors: Fan, S.; He, J.; Yan, L.; Zhang, L.; Tomczyk, S.
2014AGUFMSH12A..06F Altcode:
Ahead of CMEs usually exist the shocked sheaths, in which the background
solar corona / solar wind is heated due to the compression of the
driving CME. The other regions around the CME, e.g., the side and
wake, which may also be influenced by the CME, are the objects of this
work. Various instruments including LASCO, AIA, and CoMP observed a CME
close to the east limb on October 26th, 2013. The CME core is very hot
(~10 MK) (appearing only in the 131 channel of AIA), and ejects away
at a high speed (~330 km/s). Magnetic structures (low-lying loops and
large loop legs) on both sides and in the wake of the CME are strongly
disturbed, showing turbulent signatures with enhanced Doppler-shift
oscillations (~±15km/s) and effective thermal velocities (~60 km/s)
from the CoMP observations in the Fe XIII line. As recognized from the
CoMP Doppler-shift maps, the turbulent vortices behave differently at
various heights, illustrating torsional oscillations back and forth
around the leg axis at lower altitude and continuous rotation with
the same handedness at higher altitude. This difference may be due to
the lower part being more likely to be line-tied with the motionless
footpoint than the upper part. The turbulence of loop legs is also
revealed in the AIA animations in the Fe 171 Å and Fe 193 Å channels
with some differences between each other. The turbulence in Fe 171 Å
seems to be weaker than that in Fe 193 Å, with the former behaving
more wave-like and the latter involving more whirling vortices. The
difference in turbulence level might come from the difference in
turnover time of the vortices: ~1000s for Fe 171 Å and ~500s for Fe
193 Å. Moreover, in the wake of the CME, the eddies turning over
up and down as well as the eddies rotating horizontally are also
presented in the Fe 193 Å. The leg-like straps in Fe 171 Å seem
to be braided by the turbulent vortices, and disappear afterwards
probably due to heating by coherent current sheet formed between
braided straps. Meanwhile, low-lying loops are oscillating back and
forth during its reaction to the fast compressive waves as driven by
the CME. The subsequent brightening of the low-lying loops implies
a heating due to the dissipation of compressive waves. This work
suggests that the effects at the side and wake of the CME cannot be
ignored when considering the heating of the solar corona and solar wind.
---------------------------------------------------------
Title: A Progress Update for the COronal Solar Magnetism Observatory
for Coronal and Chromospheric Polarimetry
Authors: de Wijn, A. G.; Tomczyk, S.; Burkepile, J.
2014ASPC..489..323D Altcode:
We present a progress update for the COronal Solar Magnetism
Observatory (COSMO), consisting of a suite of three instruments:
a large-aperture coronagraph for coronal magnetometry, a full-disk
imaging spectro-polarimeter for magnetometry and plasma diagnostics
of the chromosphere and prominences, and a white-light coronagraph
to observe the K-corona. COSMO will provide unique observations of
the global coronal magnetic fields and its environment to enhance the
value of data collected by other observatories on the ground and in
space. We provide an overview of COSMO, and discuss each instrument
in some detail.
---------------------------------------------------------
Title: 3D Coronal Magnetic Field Reconstruction based on infrared
polarimetric observations
Authors: Kramar, Maxim; Lin, Haosheng; Tomczyk, Steven
2014shin.confE.102K Altcode:
Measurement of the coronal magnetic field is a crucial ingredient in
understanding the nature of solar coronal phenomena at all scales. A
significant progress has been recently achieved here with deployment
of the Coronal Multichannel Polarimeter (CoMP) of the High Altitude
Observatory (HAO). The instrument provides polarization measurements of
Fe xiii 10747 A forbidden line emission. The observed polarization are
the result of a line-of-sight (LOS) integration through a nonuniform
temperature, density and magnetic field distribution. In order resolve
the LOS problem and utilize this type of data, the vector tomography
method has been developed for 3D reconstruction of the coronal magnetic
field. The 3D electron density and temperature, needed as additional
input, have been reconstructed by tomography method based on STEREO/EUVI
data. We will present the 3D coronal density, temperature and magnetic
field resulted from these inversions.
---------------------------------------------------------
Title: Single-point Inversion of the Coronal Magnetic Field
Authors: Plowman, Joseph; Casini, Roberto; Judge, Philip G.; Tomczyk,
Steven
2014AAS...22432324P Altcode:
The Fe XIII 10747 and 10798 Å lines observed in the solar corona
are sensitive to the coronal magnetic field in such a way that,
in principle, the full vector field at a point on the line of sight
can be inferred from their combined polarization signals. This paper
presents analytical inversion formulae for the field parameters and
analyzes the uncertainty of magnetic field measurements made from such
observations, assuming emission dominated by a single region along the
line-of-sight. We consider the case of the current CoMP instrument
as well as the future COSMO and ATST instruments. Uncertainties are
estimated with a direct analytic inverse and with an MCMC algorithm. We
find that (in effect) two components of the vector field can be
recovered with CoMP, and well-recovered with COSMO or ATST, but that
the third component can only be recovered when the solar magnetic
field is strong and optimally oriented.
---------------------------------------------------------
Title: The Chromosphere and Prominence Magnetometer
Authors: de Wijn, Alfred G.; McIntosh, Scott W.; Tomczyk, Steven
2014shin.confE..76D Altcode:
The Chromosphere and Prominence Magnetometer (ChroMag) is a synoptic
instrument with the goal of quantifying the intertwined dynamics
and magnetism of the solar chromosphere and in prominences through
imaging spectro-polarimetry of the full solar disk in a synoptic
fashion. The picture of chromospheric magnetism and dynamics is
rapidly developing, and a pressing need exists for breakthrough
observations of chromospheric vector magnetic field measurements
at the true lower boundary of the heliospheric system. ChroMag will
provide measurements that will enable scientists to study and better
understand the energetics of the solar atmosphere, how prominences are
formed, how energy is stored in the magnetic field structure of the
atmosphere and how it is released during space weather events like
flares and coronal mass ejections. An essential part of the ChroMag
program is a commitment to develop and provide community access to the
`inversion' tools necessary to interpret the measurements and derive
the magneto-hydrodynamic parameters of the plasma. Measurements of an
instrument like ChroMag provide critical physical context for the Solar
Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph
(IRIS) as well as ground-based observatories such as the future Daniel
K. Inouye Solar Telescope (DKIST). <P />A prototype is currently
deployed in Boulder, CO, USA. We will present an overview of instrument
capabilities and a progress update on the ChroMag development.
---------------------------------------------------------
Title: Coronal Multi-channel Polarimeter at the Lomnicky Peak
Observatory
Authors: Schwartz, P.; Ambroz, J.; Gömöry, P.; Kozák, M.; Kučera,
A.; Rybák, J.; Tomczyk, S.; Sewell, S.; Aumiller, P.; Summers, R.;
Sutherland, L.; Watt, A.
2014IAUS..300..521S Altcode:
Coronal Multi-channel Polarimeter (CoMP-S), developed by HAO/NCAR, has
been introduced to regular operation at the Lomnicky Peak Observatory
(High Tatras in northern Slovakia, 2633 m a.s.l.) of the Astronomical
Institute of Slovak Academy of Sciences. We present here the technical
parameters of the current version of the instrument and its potential
for observations of prominences in the visual and near-IR spectral
regions. The first results derived from observations of prominences
in the Hα emission line taken during a coordinated observing campaign
of several instruments in October 2012 are shown here.
---------------------------------------------------------
Title: Coronal Magnetometry in the Future
Authors: Li, Hui; Tomczyk, Steven
2014cosp...40E1809L Altcode:
Coronal magnetic field plays a crucial role in solar activity. However,
due to the high temperature, low density and weak magnetic field
properties of the corona, it is hard to directly measure coronal
magnetic field, especially for the vector magnetic field. In this
presentation, I will briefly review the past endeavor to measure the
coronal magnetic field and present current methodology. I will introduce
in more detail about the proposed Coronal Magnetism Telescopes of China
(COMTEC) and the Coronal Solar Magnetism Observatory (COSMO) in the
United States of America. Both of them are dedicated to measure the
vector magnetic field in the corona as well as chromospheric magnetic
field. They, once established, will certainly contribute much to the
comprehensive understanding of important questions in solar physics,
such as coronal and chromospheric heating, solar wind acceleration,
global and long-time variation of coronal magnetic field, etc.
---------------------------------------------------------
Title: Preface
Authors: Tomczyk, Steven; Zhang, Jie; Bastian, Timothy; Leibacher,
John W.
2013SoPh..288..463T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Coronal Mass Ejections with the Coronal
Multichannel Polarimeter
Authors: Tian, H.; Tomczyk, S.; McIntosh, S. W.; Bethge, C.; de Toma,
G.; Gibson, S.
2013SoPh..288..637T Altcode: 2013arXiv1303.4647T
The Coronal Multichannel Polarimeter (CoMP) measures not only the
polarization of coronal emission, but also the full radiance profiles of
coronal emission lines. For the first time, CoMP observations provide
high-cadence image sequences of the coronal line intensity, Doppler
shift, and line width simultaneously over a large field of view. By
studying the Doppler shift and line width we may explore more of the
physical processes of the initiation and propagation of coronal mass
ejections (CMEs). Here we identify a list of CMEs observed by CoMP
and present the first results of these observations. Our preliminary
analysis shows that CMEs are usually associated with greatly increased
Doppler shift and enhanced line width. These new observations provide
not only valuable information to constrain CME models and probe
various processes during the initial propagation of CMEs in the low
corona, but also offer a possible cost-effective and low-risk means
of space-weather monitoring.
---------------------------------------------------------
Title: Design and measurement of the Stokes polarimeter for the
COSMO K-coronagraph
Authors: Hou, Junfeng; de Wijn, Alfred G.; Tomczyk, Steven
2013ApJ...774...85H Altcode:
We present the Stokes polarimeter for the new Coronal Solar Magnetism
Observatory K-coronagraph. The polarimeter can be used in two modes. In
observation mode, it is sensitive to linear polarization only and
operates as a "Stokes definition" polarimeter. In the ideal case, such
a modulator isolates a particular Stokes parameter in each modulation
state. For calibrations, the polarimeter can diagnose the full Stokes
vector. We present here the design process of the polarimeter, analyze
its tolerances with a Monte Carlo method, develop a way to align
the individual elements, and measure and evaluate its performance in
both modes.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory
Authors: Tomczyk, Steven; Sewell, Scott; Gallagher, Dennis; Oakley,
Phil; Summers, Rich; Burkepile, Joan; Kolinski, Don; Sutherland, Lee;
Zhang, Haiying; Wu, Zhen; Nelson, Pete
2013shin.confE..54T Altcode:
Measurements of coronal and chromospheric magnetic fields are
arguably the most important observables required for advances
in our understanding of the processes responsible for coronal
heating, coronal dynamics and the generation of space weather
that affects communications, GPS systems, space flight, and power
transmission. The Coronal Solar Magnetism Observatory (COSMO) is a
proposed ground-based suite of instruments designed for routine study
of coronal and chromospheric magnetic fields and their environment,
and to understand the formation of coronal mass ejections (CME) and
their relation to other forms of solar activity. This new facility will
be operated by the High Altitude Observatory of the National Center for
Atmospheric Research (HAO/NCAR) in support of the solar and heliospheric
community. It will replace the current NCAR Mauna Loa Solar Observatory
(http://mlso.hao.ucar.edu). COSMO will enhance the value of existing
and new observatories on the ground (SOLIS, BBO NST, Gregor, ATST,
EST, Chinese Giant Solar Telescope, NLST, FASR) and in space (SOHO,
GOES, Hinode, STEREO, SDO, IRIS, Solar-C, Solar Probe+, Solar Orbiter)
by providing unique and crucial observations of the global coronal
and chromospheric magnetic field and its evolution.
---------------------------------------------------------
Title: Coronal Magnetic Field Reconstruction based on HAO/CoMP
observations.
Authors: Kramar, Maxim; Lin, H.; Tomczyk, S.; Davila, J.
2013shin.confE..89K Altcode:
The magnetic field is the dominant force source in the solar coronal
plasma, the one that shapes its structure. Synoptic observations that
provide a direct information about the magnetic field have been recently
became available by High Altitude Observatory (HAO) Coronal Multichannel
Polarimeter (CoMP). The instrument provides linear polarization maps of
the Fe XIII 10747 A 'forbidden' line. The observed linear polarization
depends on magnetic field orientation through Hanle effect. These
observation, supplied with additional photospheric magnetic field
measurements and UV observations, are used for 3D reconstruction of
the coronal magnetic field by applying the vector tomography technique.
---------------------------------------------------------
Title: The Chromosphere and Prominence Magnetometer
Authors: de Wijn, Alfred; Bethge, Christian; McIntosh, Scott; Tomczyk,
Steven; Burkepile, Joan
2013EGUGA..1512765D Altcode:
The Chromosphere and Prominence Magnetometer (ChroMag) is a synoptic
instrument with the goal of quantifying the intertwined dynamics
and magnetism of the solar chromosphere and in prominences through
imaging spectro-polarimetry of the full solar disk in a synoptic
fashion. The picture of chromospheric magnetism and dynamics is
rapidly developing, and a pressing need exists for breakthrough
observations of chromospheric vector magnetic field measurements
at the true lower boundary of the heliospheric system. ChroMag will
provide measurements that will enable scientists to study and better
understand the energetics of the solar atmosphere, how prominences are
formed, how energy is stored in the magnetic field structure of the
atmosphere and how it is released during space weather events like
flares and coronal mass ejections. An essential part of the ChroMag
program is a commitment to develop and provide community access to the
`inversion' tools necessary to interpret the measurements and derive
the magneto-hydrodynamic parameters of the plasma. Measurements of an
instrument like ChroMag provide critical physical context for the Solar
Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph
(IRIS) as well as ground-based observatories such as the future Advanced
Technology Solar Telescope (ATST). A prototype is currently under
construction at the High Altitude Observatory of the National Center
for Atmospheric Research in Boulder, CO, USA. The heart of the ChroMag
instrument is an electro-optically tunable wide-fielded narrow-band
birefringent six-stage Lyot filter with a built-in polarimeter. We
will present a progress update on the ChroMag design, and present
results from the prototype instrument.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory
Authors: Tomczyk, S.
2012IAUSS...6E.214T Altcode:
Measurements of coronal and chromospheric magnetic fields are arguably
the most important observables required to advance our understanding
of the emergence of magnetic flux into the solar atmosphere and the
processes responsible for the production of solar activity, coronal
heating and coronal dynamics. The Coronal Solar Magnetism Observatory
(COSMO) is a proposed ground-based suite of instruments designed for
routine study of coronal and chromospheric magnetic fields and their
environment. The central instrument in this suite is a 1.5-m aperture
coronagraph. Additional instruments include a K-Coronagraph and a
Chromospheric Magnetometer (ChroMag). We will present an overview of
the COSMO project and give an update on the status, including: joint
US/China engineering development of the 1.5-m coronagraph and its
post-focus instrumentation; ongoing construction of the K-Coronagraph;
development of a prototype filter/polarimeter for ChroMag; and recent
progress in coronal field measurement with the prototype Coronal
Multi-channel Polarimeter instrument.
---------------------------------------------------------
Title: Reconstruction of the 3D Coronal Magnetic Field by Vector
Tomography with Infrared Spectropolarimetric Observations from CoMP
Authors: Kramar, M.; Lin, H.; Tomczyk, S.; Davila, J. M.; Inhester, B.
2012AGUFMSH42A..06K Altcode:
Magnetic fields determine the static and dynamic properties of the solar
corona. A significant progress has been achieved in direct measurement
of the magnetically sensitive coronal emission with deployment of
the HAO Coronal Multichannel Polarimeter (CoMP). The instrument
provides polarization measurements of Fe XIII 10747 A forbidden line
emission. The observed polarization depends on magnetic field through
the Hanle and Zeeman effects. However, because the coronal measurements
are integrated over line-of-site (LOS), it is impossible to derive the
configuration of the coronal magnetic field from a single observation
(from a single viewing direction). The vector tomography techniques
based on the infrared polarimetric measurements from several viewing
directions has been developed in order to resolve the 3D coronal
magnetic field structure over LOS. Because of the non-linear character
of the Hanle effect, the reconstruction result based on such data
is not straightforward and depends on the particular coronal field
configuration. For several possible cases of coronal magnetic field
configuration, it has been found that even just Stokes-Q and -U data
(supplied with 3D coronal density and temperature) can be used in the
vector tomography to provide a realistic 3D coronal magnetic field. The
3D coronal density and temperature needed as an supplemental input are
reconstructed by the scalar field tomography method using ultraviolet
observations from EUVI/STEREO. We will present the reconstructed 3D
coronal density, temperature and magnetic field in the range of ∼
1.3 R<SUB>⊙</SUB> obtained by the scalar and vector tomography.
---------------------------------------------------------
Title: A Space Weather Mission to the Earth's 5th Lagrangian Point
(L5)
Authors: Howard, R. A.; Vourlidas, A.; Ko, Y.; Biesecker, D. A.;
Krucker, S.; Murphy, N.; Bogdan, T. J.; St Cyr, O. C.; Davila, J. M.;
Doschek, G. A.; Gopalswamy, N.; Korendyke, C. M.; Laming, J. M.;
Liewer, P. C.; Lin, R. P.; Plunkett, S. P.; Socker, D. G.; Tomczyk,
S.; Webb, D. F.
2012AGUFMSA13D..07H Altcode:
The highly successful STEREO mission, launched by NASA in 2006,
consisted of two spacecraft in heliocentric orbit, one leading and
one trailing the Earth and each separating from Earth at the rate
of about 22.5 degrees per year. Thus the two spacecraft have been
probing different probe/Sun/Earth angles. The utility of having remote
sensing and in-situ instrumentation away from the Sun-Earth line was
well demonstrated by STEREO. Here we propose the concept of a mission
at the 5th Lagrangian "point" in the Earth/Sun system, located behind
Earth about 60 degrees to the East of the Sun-Earth line. Such a mission
would enable many aspects affecting space weather to be well determined
and thus improving the prediction of the conditions of the solar wind
as it impinges on geospace. For example, Coronal Mass Ejections can
tracked for a significant distance toward Earth, new active regions
can be observed before they become visible to the Earth observer, the
solar wind can be measured before it rotates to Earth. The advantages
of such a mission will be discussed in this presentation.
---------------------------------------------------------
Title: Stray light and polarimetry considerations for the COSMO
K-Coronagraph
Authors: de Wijn, Alfred G.; Burkepile, Joan T.; Tomczyk, Steven;
Nelson, Peter G.; Huang, Pei; Gallagher, Dennis
2012SPIE.8444E..3ND Altcode: 2012arXiv1207.0978D
The COSMO K-Coronagraph is scheduled to replace the aging Mk4
K-Coronameter at the Mauna Loa Solar Observatory of the National Center
for Atmospheric Research in 2013. We present briefly the science
objectives and derived requirements, and the optical design. We
single out two topics for more in-depth discussion: stray light,
and performance of the camera and polarimeter.
---------------------------------------------------------
Title: Optical design of the COSMO large coronagraph
Authors: Gallagher, Dennis; Tomczyk, Steven; Zhang, Haiying; Nelson,
Peter G.
2012SPIE.8444E..3PG Altcode:
The Coronal Solar Magnetism Observatory (COSMO) is a facility dedicated
to measuring magnetic fields in the corona and chromosphere of the
Sun. It will be located on a mountaintop in the Hawaiian Islands and
will replace the current Mauna Loa Solar Observatory (MLSO). COSMO
will employ a suite of instruments to determine the magnetic field
and plasma conditions in the solar atmosphere and will enhance the
value of data collected by other observatories on the ground (SOLIS,
ATST, FASR) and in space (SDO, Hinode, SOHO, GOES, STEREO, DSCOVR,
Solar Probe+, Solar Orbiter). The dynamics and energy flow in the
corona are dominated by magnetic fields. To understand the formation
of Coronal Mass Ejections (CMEs), their relation to other forms of
solar activity, and their progression out into the solar wind requires
measurements of coronal magnetic fields. The COSMO suite includes the
Large Coronagraph (LC), the Chromosphere and Prominence Magnetometer
(ChroMag) and the K-Coronagraph. The Large Coronagraph will employ a
1.5 meter fuse silica singlet lens and birefringent filters to measure
magnetic fields out to two solar radii. It will observe over a wide
range of wavelengths from 500 to 1100 nm providing the capability of
observing a number of coronal, chromospheric, and photospheric emission
lines. Of particular importance to measuring coronal magnetic fields
are the forbidden emission lines of Fe XIII at 1074.7 nm and 1079.8
nm. These lines are faint and require the very large aperture. NCAR
and NSF have provided funding to bring the COSMO Large Coronagraph to
a preliminary design review (PDR) state by the end of 2013.
---------------------------------------------------------
Title: The chromosphere and prominence magnetometer
Authors: de Wijn, Alfred G.; Bethge, Christian; Tomczyk, Steven;
McIntosh, Scott
2012SPIE.8446E..78D Altcode: 2012arXiv1207.0969D
The Chromosphere and Prominence Magnetometer (ChroMag) is conceived
with the goal of quantifying the intertwined dynamics and magnetism
of the solar chromosphere and in prominences through imaging spectro-
polarimetry of the full solar disk. The picture of chromospheric
magnetism and dynamics is rapidly developing, and a pressing need
exists for breakthrough observations of chromospheric vector magnetic
field measurements at the true lower boundary of the heliospheric
system. ChroMag will provide measurements that will enable scientists
to study and better understand the energetics of the solar atmosphere,
how prominences are formed, how energy is stored in the magnetic field
structure of the atmosphere and how it is released during space weather
events like flares and coronal mass ejections. An integral part of the
ChroMag program is a commitment to develop and provide community access
to the "inversion" tools necessary for the difficult interpretation
of the measurements and derive the magneto-hydrodynamic parameters of
the plasma. Measurements of an instrument like ChroMag provide critical
physical context for the Solar Dynamics Observatory (SDO) and Interface
Region Imaging Spectrograph (IRIS) as well as ground-based observatories
such as the future Advanced Technology Solar Telescope (ATST).
---------------------------------------------------------
Title: 3D Coronal Magnetic Field reconstructed by Vector Tomography
Method using CoMP data
Authors: Kramar, Maxim; Lin, H.; Tomczyk, S.; Inhester, B.; Davila, J.
2012shin.confE.141K Altcode:
Magnetic fields in the solar corona dominates the gas pressure
and therefore determine the static and dynamic properties of the
corona. Direct measurement of the coronal magnetic field is one of
the most challenging problems in observational solar astronomy and
recently a significant progress has been achieved here with deployment
of the HAO Coronal Multichannel Polarimeter (CoMP). The instrument
provides polarization measurements of Fe XIII 10747 A forbidden line
emission. The observed polarization depends on magnetic field through
the Hanle and Zeeman effects. However, because the coronal measurements
are integrated over line-of-site (LOS), it is impossible to derive the
configuration of the coronal magnetic field from a single observation
(from a single viewing direction). The vector tomography techniques
based on measurements from several viewing directions has the potential
to resolve the 3D coronal magnetic field structure over LOS. Because
of the non-linear character of the Hanle effect, the reconstruction
result based on such data is not straightforward and depends on the
particular coronal field configuration. Therefore, previously we also
studied what is the sensitivity of the vector tomographic inversion to
various coronal magnetic field models. For several possible cases of
coronal magnetic field configuration, it has been found that even just
Stokes-Q and -U data (supplied with 3D coronal density and temperature)
can be used in vector tomography to provide a realistic 3D coronal
magnetic field configuration. The 3D coronal density and temperature
needed as an supplemental input are reconstructed by the scalar field
tomography method using ultraviolet observations from EUVI/STEREO. We
will present the reconstructed 3D coronal magnetic field in the range
of ∼1.3 R_⊙ obtained by the vector tomographic technique that has
been applied to the CoMP data.
---------------------------------------------------------
Title: COSMO: A Facility Dedicated to the Measurement of Coronal
Magnetic Fields
Authors: Kolinski, Don J.; Gallagher, D.; Nelson, P.; Tomczyk, S.;
Zhang, H.
2012shin.confE.100K Altcode:
Measurements of coronal and chromospheric magnetic fields are
arguably the most important observables required for advances in
our understanding of the emergence of magnetic flux into the solar
atmosphere and the processes responsible for the production of solar
activity, coronal heating and coronal dynamics. The COronal Solar
Magnetism Observatory (COSMO) is a proposed ground-based suite of
instruments designed for routine study of coronal and chromospheric
magnetic fields and their environment. This new facility will be
operated by the High Altitude Observatory of the National Center for
Atmospheric Research (HAO/NCAR) in collaboration with the University of
Hawaii. It will replace the current NCAR Mauna Loa Solar Observatory
which has been collecting synoptic coronal data for over 40 years
(http://mlso.hao.ucar.edu). COSMO will enhance the value of existing
and new observatories on the ground (SOLIS, ATST, and FASR) and in space
(e.g. SDO, STEREO, Hinode, SOHO, GOES, SP+, SO) by providing unique and
crucial observations of the global coronal and chromospheric magnetic
field and its evolution.
---------------------------------------------------------
Title: The Chromospheric Magnetometer ChroMag
Authors: Bethge, Christian; de Wijn, A. G.; McIntosh, S. W.; Tomczyk,
S.; Casini, R.
2012AAS...22013506B Altcode:
We present the Chromosphere Magnetometer (ChroMag), which is part of
the Coronal Solar Magnetism Observatory (COSMO) proposed by the High
Altitude Observatory (HAO) in collaboration with the University of
Hawaii and the University of Michigan. ChroMag will perform routine
measurements of chromospheric magnetic fields in a synoptic manner. A <P
/>prototype is currently being assembled at HAO. The main component of
the instrument is a Lyot-type filtergraph polarimeter for both on-disk
and off-limb polarization measurements in <P />the spectral lines of
H alpha at 656.3 nm, Fe I 617.3 nm, Ca II 854.2 nm, He I 587.6 nm,
and He I 1083.0 nm. The Lyot filter is tunable at a fast rate. This
allows to determine line-of-sight <P />velocities in addition to the
magnetic field measurements. The instrument has a field-of-view of
up to 2.5 solar radii and will acquire data at a cadence of less than
1 minute and at a spatial resolution of 2 arcsec. The community will
have open access to the data as well as to a set of inversion tools
for an easier interpretation of the measurements. We show an overview
of the proposed instrument and first results from the protoype.
---------------------------------------------------------
Title: Recent Results from the Coronal Multi-Channel Polarimeter
Authors: Tomczyk, Steven; Bethge, C.; Gibson, S. E.; McIntosh, S. W.;
Rachmeler, L. A.; Tian, H.
2012AAS...22031001T Altcode:
The Coronal Multi-Channel Polarimeter (CoMP) instrument is a
ground-based filter/polarimeter which can image the solar corona at
wavelengths around the emission lines of FeXIII at 1074.7 and 1079.8
nm and the chromospheric emission line of HeI at 1083.0 nm. The
instrument consists of a 20-cm aperture coronagraph followed by a
Stokes polarimeter and a Lyot birefringent filter with a passband
of 0.14 nm width. Both the polarimeter and filter employ liquid
crystals for rapid electro-optical tuning. This instrument measures
the line-of-sight strength of the coronal magnetic field through the
Zeeman effect and the plane-of-sky direction of the magnetic field via
resonance scattering. The line-of-sight velocity can also be determined
from the Doppler shift. The CoMP has obtained daily observations from
the Mauna Loa Solar Observatory for almost one year. We will present
recent measurements of the polarization signatures seen with the
CoMP and a comparison with models that allow us to constrain coronal
structure. We also will present observations of coronal waves taken
with the CoMP and discuss their implications for the heating of the
solar corona and the acceleration of the solar wind.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory (COSMO)
Authors: Tomczyk, Steven
2012AAS...22020211T Altcode:
Measurements of coronal and chromospheric magnetic fields are arguably
the most important observables required in our understanding of
the emergence of magnetic flux into the solar atmosphere and the
processes responsible for the production of solar activity, coronal
heating and coronal dynamics. However, routine observations of the
strength and orientation of coronal and chromospheric magnetic fields
are not currently available. The Coronal Solar Magnetism Observatory
(COSMO) is a proposed ground-based suite of instruments designed for
routine study of coronal and chromospheric magnetic fields and their
environment. We will present an overview of the COSMO and show recent
progress in development of the COSMO observatory.
---------------------------------------------------------
Title: A First Look at Magnetic Field Data Products from SDO/HMI
Authors: Liu, Y.; Scherrer, P. H.; Hoeksema, J. T.; Schou, J.; Bai,
T.; Beck, J. G.; Bobra, M.; Bogart, R. S.; Bush, R. I.; Couvidat,
S.; Hayashi, K.; Kosovichev, A. G.; Larson, T. P.; Rabello-Soares,
C.; Sun, X.; Wachter, R.; Zhao, J.; Zhao, X. P.; Duvall, T. L., Jr.;
DeRosa, M. L.; Schrijver, C. J.; Title, A. M.; Centeno, R.; Tomczyk,
S.; Borrero, J. M.; Norton, A. A.; Barnes, G.; Crouch, A. D.; Leka,
K. D.; Abbett, W. P.; Fisher, G. H.; Welsch, B. T.; Muglach, K.;
Schuck, P. W.; Wiegelmann, T.; Turmon, M.; Linker, J. A.; Mikić,
Z.; Riley, P.; Wu, S. T.
2012ASPC..455..337L Altcode:
The Helioseismic and Magnetic Imager (HMI; Scherrer & Schou 2011)
is one of the three instruments aboard the Solar Dynamics Observatory
(SDO) that was launched on February 11, 2010 from Cape Canaveral,
Florida. The instrument began to acquire science data on March 24. The
regular operations started on May 1. HMI measures the Doppler velocity
and line-of-sight magnetic field in the photosphere at a cadence of
45 seconds, and the vector magnetic field at a 135-second cadence,
with a 4096× 4096 pixels full disk coverage. The vector magnetic
field data is usually averaged over 720 seconds to suppress the p-modes
and increase the signal-to-noise ratio. The spatial sampling is about
0".5 per pixel. HMI observes the Fe i 6173 Å absorption line, which
has a Landé factor of 2.5. These data are further used to produce
higher level data products through the pipeline at the HMI-AIA Joint
Science Operations Center (JSOC) - Science Data Processing (Scherrer et
al. 2011) at Stanford University. In this paper, we briefly describe the
data products, and demonstrate the performance of the HMI instrument. We
conclude that the HMI is working extremely well.
---------------------------------------------------------
Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic
field in the upper atmosphere of our closest star
Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad,
A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt,
W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.;
Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald,
V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.;
Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.;
Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.;
Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C.
2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P
The magnetic field plays a pivotal role in many fields of
Astrophysics. This is especially true for the physics of the solar
atmosphere. Measuring the magnetic field in the upper solar atmosphere
is crucial to understand the nature of the underlying physical
processes that drive the violent dynamics of the solar corona—that
can also affect life on Earth. SolmeX, a fully equipped solar space
observatory for remote-sensing observations, will provide the first
comprehensive measurements of the strength and direction of the
magnetic field in the upper solar atmosphere. The mission consists
of two spacecraft, one carrying the instruments, and another one in
formation flight at a distance of about 200 m carrying the occulter to
provide an artificial total solar eclipse. This will ensure high-quality
coronagraphic observations above the solar limb. SolmeX integrates two
spectro-polarimetric coronagraphs for off-limb observations, one in
the EUV and one in the IR, and three instruments for observations on
the disk. The latter comprises one imaging polarimeter in the EUV for
coronal studies, a spectro-polarimeter in the EUV to investigate the low
corona, and an imaging spectro-polarimeter in the UV for chromospheric
studies. SOHO and other existing missions have investigated the emission
of the upper atmosphere in detail (not considering polarization),
and as this will be the case also for missions planned for the near
future. Therefore it is timely that SolmeX provides the final piece of
the observational quest by measuring the magnetic field in the upper
atmosphere through polarimetric observations.
---------------------------------------------------------
Title: Constraints on coronal magnetic fields from observations of
visible and IR emission lines
Authors: Tomczyk, Steven
2012decs.confE.116T Altcode:
Information on the strength and direction of coronal magnetic fields
can be obtained from the observation of the polarization of visible
and IR emission lines. These observations are confined to the corona
above the solar limb and integrated along the line-of-sight. A
wealth of information is also available through the analysis of the
waves that permeate the corona as observed in line-of-sight velocity
measurements. I will present an overview of the strengths and weaknesses
of techniques for extracting information on coronal magnetism from these
sources, and present an assessment for future progress in this area.
---------------------------------------------------------
Title: The Chromosphere and Prominence Magnetometer
Authors: de Wijn, Alfred; Bethge, Christian; McIntosh, Scott; Tomczyk,
Steven; Casini, Roberto
2012decs.confE..63D Altcode:
ChroMag is an imaging polarimeter designed to measure on-disk
chromosphere and off-disk prominence magnetic fields using the
spectral lines of He I (587.6 and 1083 nm). It is part of the planned
CoSMO suite, which includes two more instruments: a large 1.5-m
refracting coronagraph for coronal magnetic field measurements, and
the K-Coronagraph for measurement of the coronal density. ChroMag
will provide insights in the energetics of the solar atmosphere,
how prominences are formed, and how energy is stored and released
in the magnetic field structure of the atmosphere. An essential
part of the ChroMag program is a commitment to develop and provide
community access to the "inversion" tools necessary to interpret the
measurements and derive the magneto-hydrodynamic parameters of the
plasma. A prototype instrument is currently under construction at the
High Altitude Observatory. We will present an overview of the ChroMag
instrument concept, target science, and prototype status.
---------------------------------------------------------
Title: Synoptic measurements of chromospheric and prominence magnetic
fields with the Chromosphere Magnetometer ChroMag
Authors: Bethge, C.; de Wijn, A. G.; McIntosh, S. W.; Tomczyk, S.;
Casini, R.
2012decs.confE..62B Altcode:
The Chromosphere Magnetometer is part of the Coronal Solar Magnetism
Observatory (COSMO) proposed by the High Altitude Observatory (HAO)
in collaboration with the University of Hawaii and the University of
Michigan. Routine measurements of chromospheric and coronal magnetic
fields are vital if we want to understand fundamental problems like
the energy and mass balance of the corona, the onset and acceleration
of the solar wind, the emergence of CMEs, and how these phenomena
influence space weather. ChroMag is designed as a Lyot-type filtergraph
polarimeter with an FOV of 2.5 solar radii, i.e., it will be capable of
both on-disk and off-limb polarimetric measurements. The Lyot filter
- currently being built at HAO - is tunable at a fast rate, which
allows to determine line-of-sight velocities. This will be done in
the spectral lines of H alpha at 656.3 nm, Fe I 617.3 nm, Ca II 854.2
nm, He I 587.6 nm, and He I 1083.0 nm at a high cadence of less than
1 minute, and at a moderate spatial resolution of 2 arcsec. ChroMag
data will be freely accessible to the community, along with inversion
tools for an easier interpretation of the data. A protoype instrument
for ChroMag is currently being assembled at HAO and is expected to
perform first measurements at the Boulder Mesa Lab in Summer 2012. We
present an overview of the ChroMag instrument and the current status
of the protoype.
---------------------------------------------------------
Title: Polarization Calibration of the Helioseismic and Magnetic
Imager (HMI) onboard the Solar Dynamics Observatory (SDO)
Authors: Schou, J.; Borrero, J. M.; Norton, A. A.; Tomczyk, S.;
Elmore, D.; Card, G. L.
2012SoPh..275..327S Altcode:
As part of the overall ground-based calibration of the Helioseismic
and Magnetic Imager (HMI) instrument an extensive set of polarimetric
calibrations were performed. This paper describes the polarimetric
design of the instrument, the test setup, the polarimetric model,
the tests performed, and some results. It is demonstrated that HMI
achieves an accuracy of 1% or better on the crosstalks between Q,
U, and V and that our model can reproduce the intensities in our
calibration sequences to about 0.4%. The amount of depolarization
is negligible when the instrument is operated as intended which,
combined with the flexibility of the polarimeter design, means that
the polarimetric efficiency is excellent.
---------------------------------------------------------
Title: Design and Ground Calibration of the Helioseismic and Magnetic
Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)
Authors: Schou, J.; Scherrer, P. H.; Bush, R. I.; Wachter, R.;
Couvidat, S.; Rabello-Soares, M. C.; Bogart, R. S.; Hoeksema, J. T.;
Liu, Y.; Duvall, T. L.; Akin, D. J.; Allard, B. A.; Miles, J. W.;
Rairden, R.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Wolfson,
C. J.; Elmore, D. F.; Norton, A. A.; Tomczyk, S.
2012SoPh..275..229S Altcode:
The Helioseismic and Magnetic Imager (HMI) investigation (Solar
Phys. doi:10.1007/s11207-011-9834-2, 2011) will study the solar
interior using helioseismic techniques as well as the magnetic field
near the solar surface. The HMI instrument is part of the Solar
Dynamics Observatory (SDO) that was launched on 11 February 2010. The
instrument is designed to measure the Doppler shift, intensity, and
vector magnetic field at the solar photosphere using the 6173 Å Fe I
absorption line. The instrument consists of a front-window filter, a
telescope, a set of waveplates for polarimetry, an image-stabilization
system, a blocking filter, a five-stage Lyot filter with one tunable
element, two wide-field tunable Michelson interferometers, a pair
of 4096<SUP>2</SUP> pixel cameras with independent shutters, and
associated electronics. Each camera takes a full-disk image roughly
every 3.75 seconds giving an overall cadence of 45 seconds for the
Doppler, intensity, and line-of-sight magnetic-field measurements
and a slower cadence for the full vector magnetic field. This article
describes the design of the HMI instrument and provides an overview of
the pre-launch calibration efforts. Overviews of the investigation,
details of the calibrations, data handling, and the science analysis
are provided in accompanying articles.
---------------------------------------------------------
Title: The Helioseismic and Magnetic Imager (HMI) Investigation for
the Solar Dynamics Observatory (SDO)
Authors: Scherrer, P. H.; Schou, J.; Bush, R. I.; Kosovichev, A. G.;
Bogart, R. S.; Hoeksema, J. T.; Liu, Y.; Duvall, T. L.; Zhao, J.;
Title, A. M.; Schrijver, C. J.; Tarbell, T. D.; Tomczyk, S.
2012SoPh..275..207S Altcode:
The Helioseismic and Magnetic Imager (HMI) instrument and investigation
as a part of the NASA Solar Dynamics Observatory (SDO) is designed
to study convection-zone dynamics and the solar dynamo, the origin
and evolution of sunspots, active regions, and complexes of activity,
the sources and drivers of solar magnetic activity and disturbances,
links between the internal processes and dynamics of the corona and
heliosphere, and precursors of solar disturbances for space-weather
forecasts. A brief overview of the instrument, investigation objectives,
and standard data products is presented.
---------------------------------------------------------
Title: The Coronal Solar Magnetism Observatory (COSMO)
Authors: Tomczyk, S.
2011AGUFMSH43B1952T Altcode:
Measurements of coronal and chromospheric magnetic fields are arguably
the most important observables required in our understanding of
the emergence of magnetic flux into the solar atmosphere and the
processes responsible for the production of solar activity, coronal
heating and coronal dynamics. However, routine observations of the
strength and orientation of coronal and chromospheric magnetic fields
are not currently available. The Coronal Solar Magnetism Observatory
(COSMO) is a proposed ground-based suite of instruments designed for
routine study of coronal and chromospheric magnetic fields and their
environment. We will present the capabilities of the COSMO and discuss
recent progress in these measurements with the prototype Coronal
Multi-channel Polarimeter (CoMP) instrument.
---------------------------------------------------------
Title: Vector Tomography Inversion for the 3D Coronal Magnetic Field
Based on CoMP data
Authors: Kramar, M.; Lin, H.; Tomczyk, S.; Inhester, B.; Davila, J. M.
2011AGUFMSH43B1948K Altcode:
Magnetic fields in the solar corona dominates the gas pressure
and therefore determine the static and dynamic properties of the
corona. Direct measurement of the coronal magnetic field is one of
the most challenging problems in observational solar astronomy and
recently a significant progress has been achieved here with deployment
of the HAO Coronal Multichannel Polarimeter (CoMP). The instrument
provides polarization measurements of Fe XIII 10747 A forbidden line
emission. The observed polarization depends on magnetic field through
the Hanle and Zeeman effects. However, because the coronal measurements
are integrated over line-of-site (LOS), it is impossible to derive the
configuration of the coronal magnetic field from a single observation
(from a single viewing direction). The vector tomography techniques
based on measurements from several viewing directions has the potential
to resolve the 3D coronal magnetic field structure over LOS. Because
of the non-linear character of the Hanle effect, the reconstruction
result based on such data is not straightforward and depends on the
particular coronal field configuration. Therefore we study here what is
the sensitivity of the vector tomographic inversion to sophisticated
(MHD) coronal magnetic field models. For several important cases of
magnetic field configuration, it has been found that even just Stokes-Q
and -U data (supplied with 3D coronal density and temperature) can be
used in vector tomography to provide a realistic 3D coronal magnetic
field configuration. This vector tomograpic technique is applied to
CoMP data.
---------------------------------------------------------
Title: Comparing Global Coronal Models to CoMP Data
Authors: Rachmeler, L. A.; Gibson, S. E.; Tomczyk, S.
2011AGUFMSH43B1941R Altcode:
Coronal polarization data is one of the very few available quantitative
measurements of the coronal magnetic field, which makes it extremely
attractive as a means of validating numerical models. Our forward
analysis technique produces synthetic line-of-sight integrated
polarization signals from coronal models. We present initial results
from comparisons of forward calculations of the Potential Field Source
Surface (PFSS) model to polarization data taken with the Coronal
Multichannel Polarimeter (CoMP). This research focuses on validating
the applicability of the PFSS model by determining how much the real
corona deviates from a potential field. The non-potentiality of the
corona not only has applications for testing the PFSS field, but also
for forecasting, and for finding the locations of greatest magnetic
energy storage.
---------------------------------------------------------
Title: HMI vector magnetic field products: the long-awaited release
has come! Now what?
Authors: Centeno, R.; Barnes, G.; Borrero, J.; Couvidat, S. P.;
Hayashi, K.; Hoeksema, J. T.; Leka, K. D.; Liu, Y.; Schou, J.; Schuck,
P. W.; Sun, X.; Tomczyk, S.
2011AGUFMSH31A1985C Altcode:
HMI vector magnetic field test products will be released, alongside
with the corresponding documentation, soon after the submission of this
abstract. These data represent a stage of the project at which the HMI
vector team has a large degree of confidence in the results. However,
longer-term research topics on how to improve certain aspects of the
data pipeline in general -and the spectral line inversion code in
particular- are being pursued as we get valuable input from the user
community. I will give a brief summary of the characteristics of the
released inversion data products and an update of where we stand now.
---------------------------------------------------------
Title: VFISV: Very Fast Inversion of the Stokes Vector for the
Helioseismic and Magnetic Imager
Authors: Borrero, J. M.; Tomczyk, S.; Kubo, M.; Socas-Navarro, H.;
Schou, J.; Couvidat, S.; Bogart, R.
2011SoPh..273..267B Altcode: 2009arXiv0901.2702B
In this paper we describe in detail the implementation and main
properties of a new inversion code for the polarized radiative transfer
equation (VFISV: Very Fast Inversion of the Stokes Vector). VFISV will
routinely analyze pipeline data from the Helioseismic and Magnetic
Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It
will provide full-disk maps (4096×4096 pixels) of the magnetic field
vector on the Solar Photosphere every ten minutes. For this reason
VFISV is optimized to achieve an inversion speed that will allow
it to invert sixteen million pixels every ten minutes with a modest
number (approx. 50) of CPUs. Here we focus on describing a number of
important details, simplifications and tweaks that have allowed us to
significantly speed up the inversion process. We also give details on
tests performed with data from the spectropolarimeter on-board of the
Hinode spacecraft.
---------------------------------------------------------
Title: Wavelength-diverse Polarization Modulators for Stokes
Polarimetry
Authors: de Wijn, A. G.; Tomczyk, S.; Casini, R.; Nelson, P. G.
2011ASPC..437..413D Altcode:
An increasing number of astronomical applications depend on the
measurement of polarized light. For example, our knowledge of solar
magnetism relies heavily on our ability to measure and interpret
polarization signatures introduced by magnetic field. Many new
instruments have consequently focused considerable attention
on polarimetry. For solar applications, spectro-polarimeters in
particular are often designed to observe the solar atmosphere in
multiple spectral lines simultaneously, thus requiring that the
polarization modulator employed is efficient at all wavelengths of
interest. We present designs of polarization modulators that exhibit
near-optimal modulation characteristics over broad spectral ranges. Our
design process employs a computer code to optimize the efficiency of
the modulator at specified wavelengths. We will present several examples
of modulator designs based on rotating stacks of Quartz waveplates and
ferroelectric liquid crystals (FLCs). An FLC-based modulator of this
design was recently deployed for the ProMag instrument at the Evans
Solar Facility of NSO/SP.
---------------------------------------------------------
Title: HMI: First Results
Authors: Centeno, R.; Tomczyk, S.; Borrero, J. M.; Couvidat,
S. Hayashi, K.; Hoeksema, T.; Liu, Y.; Schou, J.
2011ASPC..437..147C Altcode: 2010arXiv1012.3796C
The Helioseismic and Magnetic Imager (HMI) has just started producing
data that will help determine what the sources and mechanisms of
variability in the Sun's interior are. The instrument measures the
Doppler shift and the polarization of the Fe I 6173 Å line, on the
entire solar disk at a relatively-high cadence, in order to study
the oscillations and the evolution of the full vector magnetic field
of the solar Photosphere. After the data are properly calibrated,
they are given to a Milne-Eddington inversion code (VFISV, Borrero et
al. 2010) whose purpose is to infer certain aspects of the physical
conditions in the Sun's Photosphere, such as the full 3-D topology
of the magnetic field and the line-of-sight velocity at the solar
surface. We will briefly describe the characteristics of the inversion
code, its advantages and limitations -both in the context of the model
atmosphere and the actual nature of the data-, and other aspects of its
performance on such a remarkable data load. Also, a cross-comparison
with near-simultaneous maps from the Spectro-Polarimeter (SP) onboard
Hinode will be made.
---------------------------------------------------------
Title: A Ring of Polarized Light: Evidence for Twisted Coronal
Magnetism in Cavities
Authors: Dove, J. B.; Gibson, S. E.; Rachmeler, L. A.; Tomczyk, S.;
Judge, P.
2011ApJ...731L...1D Altcode:
Coronal prominence cavities may be manifestations of twisted or sheared
magnetic fields capable of storing the energy required to drive solar
eruptions. The Coronal Multi-Channel Polarimeter (CoMP), recently
installed at Mauna Loa Solar Observatory, can measure polarimetric
signatures of current-carrying magnetohydrodynamic (MHD) systems. For
the first time, this instrument offers the capability of daily full-Sun
observations of the forbidden lines of Fe XIII with high enough
spatial resolution and throughput to measure polarimetric signatures of
current-carrying MHD systems. By forward-calculating CoMP observables
from analytic MHD models of spheromak-type magnetic flux ropes, we show
that a predicted observable for such flux ropes oriented along the line
of sight is a bright ring of linear polarization surrounding a region
where the linear polarization strength is relatively depleted. We
present CoMP observations of a coronal cavity possessing such a
polarization ring.
---------------------------------------------------------
Title: Koronálny multikanálový polarimeter pre observatórium
Lomnický štít
---------------------------------------------------------
Title: Koronálny multikanálový polarimeter
pre observatórium Lomnický štít
---------------------------------------------------------
Title: Coronal multichannel
polarimeter for Lomnický štít Observatory.
Authors: Rybák, J.; Ambróz, J.; Gömöry, P.; Kozák, M.; Kučera,
A.; Tomczyk, S.; Sewell, S.; Summers, R.; Sutherland, L.; Watt, A.
2010nspm.conf..196R Altcode:
The contribution presents the process of development and preparation
of the Coronal Multi-channel Polarimeter (COMP-S) for the Lomnický
štít Observatory of the SAS Astronomy Institute. The design of the
device is based on the experience gained in recent years with the CoMP
(High Altitude Observatory / NCAR; Boulder, USA) instrument. The device
will be a combination of two main optical components: the Lyot tunable
filter and polarimeter, and is prepared specifically for one of the
20 cm Zeiss coronagraph at the Lomnický štít Observatory where it
will be installed in 2011. CoMP-S will differ from its predecessor
in several respects. The most important difference is that CoMP-S
will be able to observe the corona and chromospheric emission lines
in the wavelength range from 530 to 1083 nm. This feature will be
achieved using superachromatic wave plates and dichroic polarizers
with wide bandwidth. Furthermore, in the CoMP-S instrument new SWIFT
liquid crystals of Meadowlark Optics company will be used as variable
retarders instead of nematic liquid crystal retarders (LCVR) which
will considerably shorten the measuring process. Ferroelectric liquid
crystals will provide measurements of the full Stokes vector with nearly
optimal polarization throughout the whole instrument bandwidth. Recently
developed sCMOS cameras are to provide diffraction limit resolution of
observations, with the 860x680 arc second field and 30-frames-per-second
cadence. The device will be used in the Astronomical Observatory of SAS
at Lomnický štít primarily for spectrum polarimetry of prominences
and coronal loops of the active solar regions.
---------------------------------------------------------
Title: A ring of polarized light: evidence for twisted coronal
magnetism in cavities (Invited)
Authors: Dove, J.; Rachmeler, L.; Gibson, S. E.; Judge, P. G.;
Tomczyk, S.
2010AGUFMSH54A..01D Altcode:
Determining coronal magnetic fields is crucial to modeling the processes
that power and trigger solar flares and coronal mass ejections. Coronal
prominence cavities have been modeled as magnetic flux ropes, and have
been observed to erupt bodily as coronal mass ejections. One promising
technique for establishing the magnetic morphology of cavities is to
use spectropolarimetry of the infrared (IR) forbidden lines of Fe XIII
(at 1074.7 nm and 1079.8 nm). The Coronal Multi-Channel Polarimeter is
currently situated at the Mauna Loa Solar Observatory (MLSO), and has
begun taking daily full-Sun observations of line-of-sight integrated
Stokes parameters for these lines. For a variety of analytic coronal
magnetohydrodynamic models, we have determined forward-calculations
of CoMP observables using the formalism of Judge and Casini (2001). We
show that different MHD models and orientations do yield distinguishing
observational characteristics. In particular, a common characteristic
for spheroidal flux ropes oriented along the observational line of
sight is a ring of linear polarization surrounding a region where
the linear polarization strength is relatively depleted (the heart of
darkness). Such a polarization ring has been found in an observation
of a coronal cavity taken by CoMP in April 2005 from Sacramento
Peak. Cavities are ubiquitous features, particularly at this time of
the solar cycle. The daily observations to be taken by CoMP at MLSO
will allow us to further probe these structures, constraining models
of coronal magnetism and providing a testbed for future capabilities
of the proposed Coronal Solar Magnetism Observatory (COSMO).
---------------------------------------------------------
Title: The polychromatic polarization modulator
Authors: de Wijn, Alfred G.; Tomczyk, Steven; Casini, Roberto; Nelson,
Peter G.
2010SPIE.7735E..4AD Altcode: 2010SPIE.7735E.143D
An increasing number of astronomical applications depend on the
measurement of polarized light. For example, our knowledge of solar
magnetism relies heavily on our ability to measure and interpret
polarization signatures introduced by magnetic field. Many new
instruments have consequently focused considerable attention on
polarimetry. For solar applications, spectro-polarimeters in particular
are often designed to observe the solar atmosphere in multiple spectral
lines simultaneously, thus requiring that the polarization modulator
employed is efficient at all wavelengths of interest. We present
designs of polarization modulators that exhibit near-optimal modulation
characteristics over broad spectral ranges. Our design process employs a
computer code to optimize the efficiency of the modulator at specified
wavelengths. We will present several examples of modulator designs
based on rotating stacks of Quartz waveplates and Ferroelectric Liquid
Crystals (FLCs). An FLC-based modulator of this design was recently
deployed for the ProMag instrument at the Evans Solar Facility of
NSO/SP. We show that this modulator behaves according to its design.
---------------------------------------------------------
Title: Wavelength-diverse polarization modulators for Stokes
polarimetry
Authors: Tomczyk, Steven; Casini, Roberto; de Wijn, Alfred G.; Nelson,
Peter G.
2010ApOpt..49.3580T Altcode: 2010arXiv1006.3581T
Information about the three-dimensional structure of solar magnetic
fields is encoded in the polarized spectra of solar radiation by a host
of physical processes. To extract this information, solar spectra must
be obtained in a variety of magnetically sensitive spectral lines at
high spatial, spectral, and temporal resolution with high precision. The
need to observe many different spectral lines drives the development
of Stokes polarimeters with a high degree of wavelength diversity. We
present a new paradigm for the design of polarization modulators that
operate over a wide wavelength range with near optimal polarimetric
efficiency and are directly applicable to the next generation of
multi-line Stokes polarimeters. These modulators are not achromatic
in the usual sense because their polarimetric properties vary with
wavelength, but they do so in an optimal way. Thus we refer to
these modulators as polychromatic. We present here the theory behind
polychromatic modulators, illustrate the concept with design examples,
and present the performance properties of a prototype polychromatic
modulator.
---------------------------------------------------------
Title: New Observations Of The Solar Coronal Magnetism And Waves
With HAO/CoMP
Authors: McIntosh, Scott W.; Tomczyk, S.
2010AAS...21630201M Altcode:
We will present details of the observations made by the HAO Coronal
Multi-channel Polarimeter (CoMP) following its recent deployment at the
Mauna Loa Solar Observatory. As well as presenting the synoptic data
products, measurements, and data access we will discuss monitoring of
solar coronal magnetism, its evolution and MHD wave properties with
this unique instrumentation.
---------------------------------------------------------
Title: Large-Scale Flows in Prominence Cavities
Authors: Schmit, D. J.; Gibson, S. E.; Tomczyk, S.; Reeves, K. K.;
Sterling, Alphonse C.; Brooks, D. H.; Williams, D. R.; Tripathi, D.
2009ApJ...700L..96S Altcode:
Regions of rarefied density often form cavities above quiescent
prominences. We observed two different cavities with the Coronal
Multichannel Polarimeter on 2005 April 21 and with Hinode/EIS on 2008
November 8. Inside both of these cavities, we find coherent velocity
structures based on spectral Doppler shifts. These flows have speeds of
5-10 km s<SUP>-1</SUP>, occur over length scales of tens of megameters,
and persist for at least 1 hr. Flows in cavities are an example of
the nonstatic nature of quiescent structures in the solar atmosphere.
---------------------------------------------------------
Title: Time-Distance Seismology of the Solar Corona with CoMP
Authors: Tomczyk, Steven; McIntosh, Scott W.
2009ApJ...697.1384T Altcode: 2009arXiv0903.2002T
We employ a sequence of Doppler images obtained with the Coronal
Multi-channel Polarimeter (CoMP) instrument to perform time-distance
seismology of the solar corona. We construct the first k-ω diagrams of
the region. These allow us to separate outward and inward propagating
waves and estimate the spatial variation of the plane-of-sky-projected
phase speed, and the relative amount of outward and inward directed
wave power. The disparity between outward and inward wave power and the
slope of the observed power-law spectrum indicate that low-frequency
Alfvénic motions suffer significant attenuation as they propagate,
consistent with isotropic MHD turbulence.
---------------------------------------------------------
Title: Reconciling Chromospheric and Coronal Observations of
Alfvenic Waves
Authors: McIntosh, Scott W.; De Pontieu, B.; Tomczyk, S.
2009SPD....40.1303M Altcode:
We review the properties of the Alfvenic waves that were discovered
with Hinode/SOT and that have been shown to permeate the upper
chromosphere. Statistical analysis shows that, if they penetrate into
the corona, these waves carry enough energy to impact the energy balance
of the solar wind and quiet Sun corona. However, CoMP observations
of Alfven waves show much smaller resolved amplitudes than would be
expected from the leakage of chromospheric waves into the corona. We
use Monte Carlo simulations to show that line-of-sight superposition
of a mix of Alfvenic waves with properties similar to those observed
with Hinode/SOT and CoMP can reproduce the low wave amplitudes and
enhanced non-thermal line broadening observed with CoMP. Our analysis
indicates that the CoMP observations are compatible with a scenario
in which low-frequency Alfvenic waves are responsible for a large
fraction of the non-thermal broadening seen in the corona although
some portion remains from the power spectrum of the wave generation
process. This suggests that the flux carried by Alfvenic waves, in the
finely structured corona, is significant enough to impact the energy
balance of the corona and solar wind.
---------------------------------------------------------
Title: Flows and Plasma Properties in Quiescent Cavities
Authors: Schmit, Donald; Gibson, S.; Reeves, K.; Sterling, A.;
Tomczyk, S.
2009SPD....40.1015S Altcode:
Regions of rarefied density often form cavities above quiescent
prominences. In an attempt to constrain the plasma properties of
"equilibrium" cavities we conduct several diagnostics using Hinode/EIS,
STEREO/EUVI, and CoMP. One novel observation is of large scale flows in
cavities. Using different instruments to observe two distinct cavities
off the solar limb in coronal emission lines, we find that spectral
doppler shifts imply LOS velocities within cavities on the order of
1-10 km/s. These flows occur over length scales of several hundred Mm
and persist for hours.
---------------------------------------------------------
Title: Magnetically driven activity in the solar corona: a path to
understanding the energetics of astrophysical plasmas
Authors: Gibson, Sarah; Bastian, Tim; Lin, Haoscheng; Low, B. C.;
Tomczyk
2009astro2010S..94G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Time Distance Coronal Seismology With the CoMP Instrument
Authors: Tomczyk, S.; McIntosh, S.
2008AGUFMSH11A..01T Altcode:
Recent velocity imaging observations obtained with the Coronal
Multi-channel Polarimeter (CoMP) instrument reveal the existence of
ubiquitous propagating Alfvén waves in the solar corona. These data
present an exciting opportunity for probing the structure and magnetic
topology of the coronal plasma through coronal seismology. We present
the results of a time-distance analysis of the wave observations
which allows the determination of the phase speed of the waves and the
relative quantity of outward and inward wave flux. This analysis also
provides a k-omega diagnostic diagram of coronal waves. We discuss
current and future prospects for coronal seismology with these data.
---------------------------------------------------------
Title: A Coherence-Based Approach for Tracking Waves in the Solar
Corona
Authors: McIntosh, Scott W.; De Pontieu, Bart; Tomczyk, Steven
2008SoPh..252..321M Altcode: 2008arXiv0808.2978M; 2008SoPh..tmp..162M
We consider the problem of automatically (and robustly) isolating
and extracting information about waves and oscillations observed
in EUV image sequences of the solar corona with a view to near
real-time application to data from the Atmospheric Imaging Array
(AIA) on the Solar Dynamics Observatory (SDO). We find that a simple
coherence/travel-time based approach detects and provides a wealth
of information on transverse and longitudinal wave phenomena in the
test sequences provided by the Transition Region and Coronal Explorer
(TRACE). The results of the search are pruned (based on diagnostic
errors) to minimize false-detections such that the remainder provides
robust measurements of waves in the solar corona, with the calculated
propagation speed allowing automated distinction between various
wave modes. In this paper we discuss the technique, present results
on the TRACE test sequences, and describe how our method can be
used to automatically process the enormous flow of data (≈1 Tb
day<SUP>−1</SUP>) that will be provided by SDO/AIA.
---------------------------------------------------------
Title: A new spectro-polarimeter for solar prominence and filament
magnetic field measurements
Authors: Elmore, David F.; Casini, Roberto; Card, Greg L.; Davis,
Marc; Lecinski, Alice; Lull, Ron; Nelson, Peter G.; Tomczyk, Steven
2008SPIE.7014E..16E Altcode: 2008SPIE.7014E..39E
We are constructing a spectro-Âpolarimeter using the 40-Âcm
coronagraph at the Evans Solar Facility of the National Solar
Observatory in Sunspot, NM for the purpose of measuring the vector
magnetic field in prominences and filaments. The Prominence Magnetometer
(ProMag) is comprised of a polarization modulation package and a
spectrograph. The modulation optics are located at the prime focus
of the coronagraph along with calibration optics and a beamsplitter
that creates two beams of orthogonal Stokes states. The spectrograph
resides at the coude focus of the coronagraph. The polarizations of the
two chromospheric lines of neutral helium, at 587.6 nm and 1083.0 nm,
are to be observed simultaneously. We present details of the design
of the spectro-Âpolarimeter.
---------------------------------------------------------
Title: The feasibility of large refracting telescopes for solar
coronal research
Authors: Nelson, Peter G.; Tomczyk, Steven; Elmore, David F.; Kolinski,
Donald J.
2008SPIE.7012E..31N Altcode: 2008SPIE.7012E.104N
Measuring magnetic fields in the solar corona requires a large aperture
telescope with exceptionally low levels of scattered light. For
internally-occulted coronagraphs the main source is scattering from
dust or microroughness on the primary lens or mirror. We show refracting
primaries offer significantly lower levels for both sources. To observe
magnetic fields in the solar corona with scientifically interesting
spatial and temporal resolutions, a 1 meter aperture or larger is
required. For a long time such large-scale refractors have been
deemed impractical or impossible to construct due to gravitational
deformation of the lens. We present the results of finite-element
and optical analyses of the gravitational deformation, stress-induced
birefringence, and absorptive heating of a (see manuscript)1.5 meter f/5
fused silica lens. These studies demonstrate the traditional objections
to large refractors are unfounded and large refracting primaries have
unique capabilities.
---------------------------------------------------------
Title: Multi-wavelength Comparison of Prominence Cavities
Authors: Schmit, D. J.; Gibson, S.; de Toma, G.; Reeves, K.; Tripathi,
D.; Kucera, T.; Marque, C.; Tomczyk, S.
2008AGUSMSP43B..04S Altcode:
Recent observational campaigns have brought together a wealth of
data specifically designed to explore the physical properties and
dynamics of prominence cavities. In particular, STEREO and Hinode
data have provided new perspectives on these structures. In order to
effectively analyze the data in a cohesive manner, we produce overlays
of several distinct and complimentary datasets including SOHO UVCS,
CDS, and EIT, Hinode SOT and EIS, STEREO SECCHI, TRACE, and Nancay
Radioheliograph data as well as new observations of coronal magnetic
fields in cavities from the Coronal Multichannel Polarimeter. We are
thus able to investigate how sensitive morphology is to the wavelength
observed which details the nature of the plasma in the cavity.
---------------------------------------------------------
Title: An Instrument to Measure Coronal Emission Line Polarization
Authors: Tomczyk, S.; Card, G. L.; Darnell, T.; Elmore, D. F.; Lull,
R.; Nelson, P. G.; Streander, K. V.; Burkepile, J.; Casini, R.; Judge,
P. G.
2008SoPh..247..411T Altcode: 2008SoPh..tmp....3T
We have constructed an instrument to measure the polarization of light
emitted by the solar corona in order to constrain the strength and
orientation of coronal magnetic fields. We call this instrument the
Coronal Multichannel Polarimeter (CoMP). The CoMP is integrated into
the Coronal One Shot coronagraph at Sacramento Peak Observatory and
employs a combination birefringent filter and polarimeter to form
images in two wavelengths simultaneously over a 2.8R<SUB>⊙</SUB>
field of view. The CoMP measures the complete polarization state at
the 1074.7 and 1079.8 Fe XIII coronal emission lines, and the 1083.0
nm He I chromospheric line. In this paper we present design drivers
for the instrument, provide a detailed description of the instrument,
describe the calibration methodology, and present some sample data
along with estimates of the uncertainty of the measured magnetic field.
---------------------------------------------------------
Title: The COronal Solar Magnetism Observatory
Authors: Burkepile, J.; Tomczyk, S.; Lin, H.; Zurbuchen, T.; Judge,
P.; Casini, R.
2007AGUFMSH53A1070B Altcode:
Measurements of coronal and chromospheric magnetic fields are
arguably the most important observables required for advances in
our understanding of the emergence of magnetic flux into the solar
atmosphere and the processes responsible for the production of solar
activity, coronal heating and coronal dynamics. The COronal Solar
Magnetism Observatory (COSMO) is a proposed ground-based suite of
instruments designed for routine study of coronal and chromospheric
magnetic fields and their environment. The facility consists of 3
instruments: 1) a meter-class aperture coronal magnetometer devoted
to obtaining the highest quality polarimetric data of forbidden lines
of Fe XIII 1074.7 and 1079.8 nm.; 2) a chromosphere and prominence
magnetometer devoted primarily to measurements of lines of helium
(D3, 1083 nm) and perhaps Halpha, that will provide full disk vector
magnetic field observations; 3) a white-light polarized-brightness (pB)
coronagraph that will observe down to 1.05 solar radii at very high
time cadence (15 seconds) at high signal-to-noise. This new facility
will be operated by the High Altitude Observatory of the National
Center for Atmospheric Research (HAO/NCAR) in collaboration with the
University of Hawaii and the University of Michigan. COSMO will enhance
the value of existing and new observatories on the ground (SOLIS, ATST,
and FASR) and in space (SOHO, TRACE, GOES, SOLAR-B, STEREO, SDO) by
providing unique and crucial observations of the global coronal and
chromospheric magnetic field and its evolution.
---------------------------------------------------------
Title: Alfven Waves in the Solar Corona
Authors: Tomczyk, S.; McIntosh, S. W.; Keil, S. L.; Judge, P. G.;
Schad, T.; Seeley, D. H.; Edmondson, J.
2007AGUFMSH21A0289T Altcode:
We present observations of the coronal intensity, line-of-sight
velocity, and linear polarization obtained in the FeXIII 1074.7 nm
coronal emission line with the Coronal Multi-channel Polarimeter
(CoMP) instrument. Analysis of these observations reveal ubiquitous
upward propagating waves with phase speeds of 1-4 Mm/s and trajectories
consistent with the direction of the magnetic field inferred from the
linear polarization measurements. We can definitively identify these
as Alfvén waves. An estimate of the energy carried by the waves that
we spatially resolve indicates that they are unable to heat the solar
corona, however, unresolved waves may carry sufficient energy.
---------------------------------------------------------
Title: Observing the Influence of Alfven Waves on the Energetics of
the Quiet Solar Corona and Solar Wind
Authors: McIntosh, S. W.; de Pontieu, B.; Tomczyk, S.
2007AGUFMSH21A0288M Altcode:
We will present and discuss recent observations of Alfvén waves in the
solar chromosphere, from the Solar Optical Telescope (SOT) on Hinode,
and in the corona, from HAO's ground-based Coronal Multi-channel
Polarimeter (CoMP). These observations unambiguously demonstrate, for
the first time, that the magnetic chromosphere and corona are riddled
with 3- and 5-minute (3-5mHz) Alfvénic oscillations predominantly
propagating outward into the heliosphere. The combined analysis of these
observations, augmented by spectroscopic data from SOHO/SUMER, provide
a compelling look at the influence and importance of ubiquitously
driven Alfvén waves in heating the quiet solar corona and driving
the solar wind. Indeed, we believe that these direct observations of
a low-frequency wave input must provoke a re-evaluation of solar wind
acceleration by high frequency (kHz) ion-cyclotron modes.
---------------------------------------------------------
Title: Alfvén Waves in the Solar Corona
Authors: Tomczyk, S.; McIntosh, S. W.; Keil, S. L.; Judge, P. G.;
Schad, T.; Seeley, D. H.; Edmondson, J.
2007Sci...317.1192T Altcode:
Alfvén waves, transverse incompressible magnetic oscillations, have
been proposed as a possible mechanism to heat the Sun’s corona
to millions of degrees by transporting convective energy from the
photosphere into the diffuse corona. We report the detection of
Alfvén waves in intensity, line-of-sight velocity, and linear
polarization images of the solar corona taken using the FeXIII
1074.7-nanometer coronal emission line with the Coronal Multi-Channel
Polarimeter (CoMP) instrument at the National Solar Observatory, New
Mexico. Ubiquitous upward propagating waves were seen, with phase speeds
of 1 to 4 megameters per second and trajectories consistent with the
direction of the magnetic field inferred from the linear polarization
measurements. An estimate of the energy carried by the waves that we
spatially resolved indicates that they are too weak to heat the solar
corona; however, unresolved Alfvén waves may carry sufficient energy.
---------------------------------------------------------
Title: Coronal Seismology: The Search for Propagating Waves in
Coronal Loops
Authors: Schad, Thomas A.; Seeley, D.; Keil, S. L.; Tomczyk, S.
2007AAS...210.9113S Altcode: 2007BAAS...39Q.206S
We report on Doppler observations of the solar corona obtained in
the Fe XeXIII 1074.7nm coronal emission line with the HAO Coronal
Multi-Channel Polarimeter (CoMP) mounted on the NSO Coronal One Shot
coronagraph located in the Hilltop Facility of NSO/Sacramento Peak. The
COMP is a tunable filtergraph instrument that records the entire corona
from the edge of the occulting disk at approximately 1.03 Rsun out to
1.4 Rsun with a spatial resolution of about 4” x 4”. COMP can be
rapidly scanned through the spectral line while recording orthogonal
states of linear and circular polarization. The two dimensional spatial
resolution allows us to correlate temporal fluctuations observed in one
part of the corona with those seen at other locations, in particular
along coronal loops. Using cross spectral analysis we find that the
observations reveal upward propagating waves that are characterized
by Doppler shifts with rms velocities of 0.3 km/s, peak wave power
in the 3-5 mHz frequency range, and phase speeds 1-3 Mm/s. The wave
trajectories are consistent with the direction of the magnetic field
inferred from the linear polarization measurements. We discuss the phase
and coherence of these waves as a function of height in the corona and
relate our findings to previous observations. The observed waves appear
to be Alfvenic in character. <P />"Thomas Schad was supported through
the National Solar Observatory Research Experiences for Undergraduate
(REU) site program, which is co-funded by the Department of Defense in
partnership with the National Science Foundation REU Program." Daniel
Seeley was supported through the National Solar Observatory Research
Experience for Teachers (RET) site program, which is funded by the
National Science Foundation RET program.
---------------------------------------------------------
Title: COSMO: The Coronal Solar Magnetism Observatory
Authors: Burkepile, Joan; Tomczyk, S.; Lin, H.; Zurbuchen, T.;
Casini, R.
2007AAS...210.2519B Altcode: 2007BAAS...39..134B
The COronal Solar Magnetism Observatory (COSMO) is a proposed
ground-based suite of instruments designed to study coronal magnetic
fields and their environment using the polarization of forbidden
emission lines in the infrared. Supporting instruments focus on
prominence and chromospheric magnetometry and imaging and the evolution
of the electron scattered corona (K-corona). COSMO will address
one of the least understood problems in Sun-Earth connections: the
coronal magnetic field using breakthrough techonologies that have been
successfully demonstrated with proof-of-concept instrumentation. We will
present information about COSMO and science results from the prototype
instruments, including the detection of Alfven waves in the corona.
---------------------------------------------------------
Title: Magnetic Field Vector Retrieval With the Helioseismic and
Magnetic Imager
Authors: Borrero, J. M.; Tomczyk, S.; Norton, A.; Darnell, T.; Schou,
J.; Scherrer, P.; Bush, R.; Liu, Y.
2007SoPh..240..177B Altcode: 2006astro.ph.11565B
We investigate the accuracy to which we can retrieve the solar
photospheric magnetic field vector using the Helioseismic and Magnetic
Imager (HMI) that will fly onboard of the Solar Dynamics Observatory by
inverting simulated HMI profiles. The simulated profiles realistically
take into account the effects of the photon noise, limited spectral
resolution, instrumental polarization modulation, solar p modes, and
temporal averaging. The accuracy of the determination of the magnetic
field vector is studied by considering the different operational modes
of the instrument.
---------------------------------------------------------
Title: Spectral Line Selection for HMI
Authors: Norton, A. A.; Pietarila Graham, J. D.; Ulrich, R. K.;
Schou, J.; Tomczyk, S.; Liu, Y.; Lites, B. W.; López Ariste, A.;
Bush, R. I.; Socas-Navarro, H.; Scherrer, P. H.
2006ASPC..358..193N Altcode:
We present information on two spectral lines, Fe I 6173 Å and Ni I 6768
Å, that were candidates for use in the Helioseismic and Magnetic Imager
(HMI) instrument. Both Fe I and Ni I profiles have clean continuum and
no blends that threaten performance. The higher Landé factor of Fe
I means its operational velocity range in regions of strong magnetic
field is smaller than for Ne I. Fe I performs better than Ni I for
vector magnetic field retrieval. Inversion results show that Fe I
consistently determines field strength and flux more accurately than
the Ni I line. Inversions show inclination and azimuthal errors are
recovered to ≈2° above 600 Mx/cm<SUP>2</SUP> for Fe I and above
1000 Mx/cm<SUP>2</SUP> for Ni I. The Fe I line was recommended, and
ultimately chosen, for use in HMI.
---------------------------------------------------------
Title: Quiet-Sun Magnetism Seen with a Mn Line: Km-Sized Magnetic
Structures
Authors: López Ariste, A.; Ramírez Vélez, J. C.; Tomczyk, S.;
Casini, R.; Semel, M.
2006ASPC..358...54L Altcode:
We observed Manganese lines with large hyperfine structure and used them
to disentangle strength from flux in the measurement of photospheric
magnetic fields. In observations of the quiet sun with both ASP and
THEMIS, we measure flux from the amplitude of Stokes V in Fe lines, and
the Mn line, crudely analyzed, places the field strength either above
or below a threshold of 600 G, which is set by the atomic structure. In
the case of THEMIS observations, having determined magnetic flux and
field strength for every pixel, one can estimate filling factors of
the magnetic field and determine characteristic scales. Structures at
scales smaller than 50 km are revealed.
---------------------------------------------------------
Title: Magnetic Field Vector Retrieval with HMI
Authors: Borrero, J. M.; Tomczyk, S.; Norton, A. A.; Darnell, T.;
Schou, J.; Scherrer, P.; Bush, R. I.; Lui, Y.
2006ASPC..358..144B Altcode:
The Helioseismic and Magnetic Imager (HMI), on board the Solar Dynamics
Observatory (SDO), will begin data acquisition in 2008. It will provide
the first full-disk, high temporal cadence observations of the full
Stokes vector with a 0.5 arcsec pixel size. This will allow for a
continuous monitoring of the Solar magnetic-field vector. HMI data will
advance our understanding of the small- and large-scale magnetic field
evolution, its relation to the solar and global dynamic processes,
coronal field extrapolations, flux emergence, magnetic helicity, and
the nature of the polar magnetic fields. We summarize HMI's expected
operation modes, focusing on the polarization cross-talk induced
by the solar oscillations, and how this affects the magnetic-field
vector determination.
---------------------------------------------------------
Title: Spectral Line Selection for HMI: A Comparison of Fe I 6173
Å and Ni I 6768 Å
Authors: Norton, A. A.; Graham, J. Pietarila; Ulrich, R. K.; Schou,
J.; Tomczyk, S.; Liu, Y.; Lites, B. W.; Ariste, A. López; Bush,
R. I.; Socas-Navarro, H.; Scherrer, P. H.
2006SoPh..239...69N Altcode: 2006SoPh..tmp...88N; 2006astro.ph..8124N
We present a study of two spectral lines, Fe I 6173 Å and Ni I 6768 Å,
that were candidates to be used in the Helioseismic and Magnetic Imager
(HMI) for observing Doppler velocity and the vector magnetic field. The
line profiles were studied using the Mt. Wilson Observatory, the
Advanced Stokes Polarimeter and the Kitt Peak-McMath Pierce telescope
and one-meter Fourier transform spectrometer atlas. Both Fe I and Ni
I profiles have clean continua and no blends that threaten instrument
performance. The Fe I line is 2% deeper, 15% narrower, and has a 6%
smaller equivalent width than the Ni I line. The potential of each
spectral line to recover pre-assigned solar conditions is tested
using a least-squares minimization technique to fit Milne-Eddington
models to tens of thousands of line profiles that have been sampled
at five spectral positions across the line. Overall, the Fe I line
has a better performance than the Ni I line for vector-magnetic-field
retrieval. Specifically, the Fe I line is able to determine field
strength, longitudinal and transverse flux four times more accurately
than the Ni I line in active regions. Inclination and azimuthal angles
can be recovered to ≈2<SUP>°</SUP> above 600 Mx cm<SUP>−2</SUP>
for Fe I and above 1000 Mx cm<SUP>−2</SUP> for Ni I. Therefore, the
Fe I line better determines the magnetic-field orientation in plage,
whereas both lines provide good orientation determination in penumbrae
and umbrae. We selected the Fe I spectral line for use in HMI due to
its better performance for magnetic diagnostics while not sacrificing
velocity information. The one exception to the better performance of the
Fe I line arises when high field strengths combine with high velocities
to move the spectral line beyond the effective sampling range. The
higher g<SUB>eff</SUB> of Fe I means that its useful range of velocity
values in regions of strong magnetic field is smaller than Ni I.
---------------------------------------------------------
Title: The Coronal Solar Magnetic Observatory (COSMO)
Authors: Tomczyk, S.; Zurbuchen, T.; Kuhn, J.; Lin, H.; Judge, P.;
Burkepile, J.; Casini, R.
2006AGUFMSM12A..03T Altcode:
Measurement of magnetic fields in the corona is arguably the most
important observable required for advances in our understanding of
the emergence of magnetic flux into the solar atmosphere and the
processes responsible for the production of solar activity, coronal
heating and coronal dynamics. We discuss plans for the COronal Solar
Magnetic Observatory (COSMO), which is a proposed ground-based suite
of instruments designed to routinely study coronal magnetic fields and
their environment. The core of the facility includes a meter-class
coronagraph with instrumentation dedicated to measuring the coronal
magnetic field using the polarization of forbidden emission lines in
the infrared. Supporting instruments focus on prominence magnetometry
and the dynamics of the electron-scattered corona (K-corona) and
chromosphere. In addition to acquiring routine synoptic observations
of coronal magnetic fields, the COSMO project will include the
establishment of a community-based user advisory panel to accept
observational campaigns submitted by members of the scientific community
at-large. COSMO will enhance the value of existing and new observatories
on the ground (SOLIS, ATST, FASR) and in space (SOHO, TRACE, GOES,
Solar-B, STEREO and SDO) by providing unique and crucial observations
of the global coronal magnetic field and its evolution and dynamics.
---------------------------------------------------------
Title: Quiet sun magnetic field diagnostics with a Mn line
Authors: López Ariste, A.; Tomczyk, S.; Casini, R.
2006A&A...454..663L Altcode:
Context: .The Mn line at 553 nm shows strong spectral features in both
intensity and polarization profiles due to the hyperfine structure of
the atom. These features, their presence or absence, are known to be
dependent on the magnetic regime to which the Mn atom is subject.<BR
/> Aims: .Our objective is to disentangle strong kilo-Gauss (kG)
fields from relatively weak hecto-Gauss (hG) fields in the quiet sun,
and compute relative filling factors on the resolution element.<BR />
Methods: .We observed the 553 nm Mn line in a quiet sun area with the
Advanced Stokes Polarimeter, and we introduce an in-line ratio between
different spectral features. Filling factors can be retrieved from
the measurement of this ratio and the total longitudinal flux.<BR />
Results: .In the photospheric network the kG dominate the magnetic flux,
although out of the higher concentration areas the hG fields dominate in
surface coverage. For the internetwork (granules and lanes confounded)
the hG are dominant both in surface and total flux. <BR />
---------------------------------------------------------
Title: High Resolution Spectropolarimetry of Penumbral Formation
with IBIS
Authors: Reardon, Kevin; Casini, R.; Cavallini, F.; Tomczyk, S.;
Rouppe van der Voort, L.; Van Noort, M.; Woeger, F.; Socas Navarro,
H.; IBIS Team
2006SPD....37.3503R Altcode: 2006BAAS...38..260R
We present the results of first spectropolarimetric observations
made with the Interferometric Bidimensional Spectrometer (IBIS)
at the NSO/Dunn Solar Telescope. The use of narrowband imaging and
post-facto reconstruction techniques allows for observations close
to the diffraction limit of the vector magnetic field. We will show
observations of the the formation of an individual penumbral filament
around a small pore. We measure the magnetic field and velocity field
of the forming penumbral filament. The spectropolarimetric mode of
IBIS will be available to the community in the fall of 2006.
---------------------------------------------------------
Title: Spinor: Visible and Infrared Spectro-Polarimetry at the
National Solar Observatory
Authors: Socas-Navarro, Hector; Elmore, David; Pietarila, Anna;
Darnell, Anthony; Lites, Bruce W.; Tomczyk, Steven; Hegwer, Steven
2006SoPh..235...55S Altcode: 2005astro.ph..8685S
The Spectro-Polarimeter for Infrared and Optical Regions (SPINOR)
is a new spectro-polarimeter that will serve as a facility instrument
for the Dunn Solar Telescope at the National Solar Observatory. This
instrument is capable of achromatic polarimetry over a very broad range
of wavelengths, from 430 to 1600 nm, allowing for the simultaneous
observation of several visible and infrared spectral regions with full
Stokes polarimetry. Another key feature of the design is its flexibility
to observe virtually any combination of spectral lines, limited only
by practical considerations (e.g., the number of detectors available,
space on the optical bench, etc.).
---------------------------------------------------------
Title: Mauna Loa Solar Observatory and the SSSC Great Observatory
Authors: Burkepile, J.; Darnell, T.; Tomczyk, S.
2005AGUFMSH51C1220B Altcode:
Solar observations of the low corona, He I 1083.0 nm and H-alpha
obtained at the Mauna Loa Solar Observatory (MLSO) provide an
extensive complimentary and supporting dataset to many NASA missions
such as STEREO, SDO, TRACE and Solar-B. These datasets, coupled with
the Coronal Multichannel Polarimeter (CoMP), due to begin taking
synoptic magnetic field measurements in the low corona in 2006,
can provide valuable scientific contributions and extensions to
many NASA programs. The Advanced Coronal Observing System (ACOS)
at MLSO is comprised of three instruments: PICS, CHIP and Mk4,
which together record the solar chromosphere and low corona every
three minutes over a 9 hour observing day for an average of 340 days
per year. The Coronal Multichannel Polarimeter (CoMP), images the low
corona at 1074.7 and 1079.8 nm and the off limb chromosphere at 1083.0
nm. From these images, the line-of-sight (LOS) magnetic field strength
and plane of sky direction are inferred from Stokes parameters. CoMP
data were taken throughout the Summer of 2005 at the Sacramento Peak
Observatory in Sunspot NM and plans are underway to start continuous
synoptic observations there in 2006. Here we present highlights of
the MLSO and CoMP datasets, emphasize recent work using NASA and MLSO
datasets and discuss plans to provide new data products that compliment
NASA data as well as combine NASA, MLSO and CoMP observations.
---------------------------------------------------------
Title: Full Stokes Spectropolarimetry of Hα in Prominences
Authors: López Ariste, A.; Casini, R.; Paletou, F.; Tomczyk, S.;
Lites, B. W.; Semel, M.; Landi Degl'Innocenti, E.; Trujillo Bueno,
J.; Balasubramaniam, K. S.
2005ApJ...621L.145L Altcode:
We report on spectropolarimetric observations of Hα in prominences
made with the Télescope Héliographique pour l'Etude du Magnétisme et
des Instabilités Solaires and the High Altitude Observatory/Advanced
Stokes Polarimeter. Stokes Q and U show the expected profile shape from
resonance scattering polarization and the Hanle effect. In contrast,
most of the time, Stokes V does not show the antisymmetric profile shape
typical of the Zeeman effect but a profile that indicates the presence
of strong atomic orientation in the hydrogen levels, to an extent that
cannot be explained by invoking the alignment-to-orientation transfer
mechanism induced by the prominence magnetic field. We found that the
largest signal amplitudes of Stokes V (comparable to that of Stokes
Q and U) could be produced by a process of selective absorption of
circularly polarized radiation from the photosphere, which requires
that the prominence be in the vicinity of an active region. Although
recent observations of active region filaments indicate such a
selective absorption mechanism as a plausible explanation of the
anomalous signals observed, the particular set of conditions that
must be met suggest that a different explanation may be required
to explain the almost ubiquitous symmetric V signal observed in Hα
prominences. Therefore, we speculate that an alternative mechanism
inducing strong atomic orientation at the observed level could be due
to the presence of electric fields inducing an electric Hanle effect
on Hα. Although we are still working toward a careful modeling of
this effect, including both electric and magnetic fields, we present
some preliminary considerations that seem to support this possibility.
---------------------------------------------------------
Title: Magnetic Field Measurements from The Coronal Multi-Channel
Polarimeter
Authors: Tomczyk, S.
2004AGUFMSH31B..04T Altcode:
We have constrcted a filter-based polarimeter optimized for the
measurement of magnetic fileds in the solar corona. The instrument will
observe the coronal emission lines of FeXIII at 1074.7 and 1079.8 nm as
well as the chromospheric HeI emission line at 1083 nm. The instrument
consists of a polarimeter allowing complete Stokes I,Q,U,V measurement
followed by a Lyot birefringent filter with dual passbands of 0.14 nm
width. Both the polarimeter and filter employ liquid crystals for rapid
electro-optical tuning. Measurement of the longitudinal Zeeman effect
provides information on the strength of the line-of-sight component
of the magnetic field while the observation of resonance scattering
will constrain the plane-of-sky field direction. Precise measurement
of plasma velocity is also possible. Such measurements are critical for
addressing many outstanding problems in coronal physics. This instrument
was deployed to the 20-cm One Shot coronagraph at NSO's Sacramento
Peak Observatory in January of 2004. Observations were obtained during
observing runs in March, May and August of 2004. Results from these
observing runs will be presented.
---------------------------------------------------------
Title: Background-Induced Measurement Errors of the Coronal Intensity,
Density, Velocity, and Magnetic Field
Authors: Penn, M. J.; Lin, H.; Tomczyk, S.; Elmore, D.; Judge, P.
2004SoPh..222...61P Altcode:
The effect of a background signal on the signal-to-noise ratio is
discussed, with particular application to ground-based observations of
emission lines in the solar corona with the proposed Advanced Technology
Solar Telescope. The concepts of effective coronal aperture and
effective coronal integration time are introduced. Specific expressions
are developed for the 1σ measurement errors for coronal intensity,
coronal electron density, coronal velocity, and coronal magnetic field
measurements using emission lines and including a background.
---------------------------------------------------------
Title: Initial Magnetic Field Measurements from The Coronal
Multi-Channel Polarimeter
Authors: Tomczyk, S.; Card, G. L.; Darnell, T.; Elmore, D. F.; Casini,
R.; Judge, P. G.; Burkepile, J.
2004AAS...204.2002T Altcode: 2004BAAS...36..686T
We have constrcted a filter-based polarimeter optimized for the
measurement of magnetic fileds in the solar corona. The instrument will
observe the coronal emission lines of FeXIII at 1074.7 and 1079.8 nm as
well as the chromospheric HeI emission line at 1083 nm. The instrument
consists of a polarimeter allowing complete Stokes I,Q,U,V measurement
followed by a Lyot birefringent filter with dual passbands of 0.14
nm width. Both the polarimeter and filter employ liquid crystals for
rapid electro-optical tuning. This instrument was deployed to the
20-cm One Shot coronagraph at NSO's Sacramento Peak Observatory in
January of 2004. <P />Measurement of the longitudinal Zeeman effect
provides information on the strength of the line-of-sight component
of the magnetic field while the observation of resonance scattering
will constrain the plane-of-sky field direction. Precise measurement
of plasma velocity is also possible. Such measurements are critical
for addressing many outstanding problems in coronal physics. <P />The
operation and performance of the instrument will be described. We
will also describe the methodology for the coronal magnetic field
measurement. Initial measurements taken with the instrument will be
presented. This research was supported by the NSF.
---------------------------------------------------------
Title: Multi-Channel Polarimeter for Coronal Magnetic Filed
Measurements
Authors: Tomczyk, S.
2003AGUFMSH42D..03T Altcode:
We are currently building a filter-based polarimeter optimized
for the measurement of magnetic fileds in the solar corona through
observations of the coronal emission lines of Fe XIII at 1074.7 and
1079.8 nm. The instrument consists of a polarimeter allowing complete
Stokes I,Q,U,V measurement followed by a Lyot birefringent filter with
dual passbands of 0.14 nm width. Both the polarimeter and filter employ
liquid crystals for rapid electro-optical tuning. This instrument will
be deployed at the One Shot coronagraph at NSO Sac Peak. Measurement of
the longitudinal Zeeman effect will yield information on the strength
of the line-of-sight component of the magnetic field while the
observation of resonance scattering will constrain the plane-of-sky
field direction. Precise measurement of plasma velocity will also be
possible. Such measurements are critical for addressing many outstanding
problems in coronal physics. The operation and performance of the
instrument will be described. We will also describe the methodology
for the coronal magnetic field measurement. Preliminary measurements
with the instrument at the One Shot coronagraph will be presented.
---------------------------------------------------------
Title: A Coronal Multi Channel Polarimeter For Magnetic Field
Measurements
Authors: Darnell, T.; Tomczyk, S.; Card, G.; Judge, P. G.; Casini,
R.; Burkepile, J.
2003AGUFMSH42B0505D Altcode:
The Coronal Multi-channel Polarimeter (CoMP) is a filter-based
polarimeter designed to provide quantitative measurements of magnetic
fields in the solar corona. It will measure the Stokes parameters
at the 1074.7 and 1079.8 FeXIII coronal emission lines (1.67 x 106
degrees K), and the 1083.0 nm HeI chromospheric line. The CoMP is
based on a four stage birefringent filter and is designed such that
the corona is imaged in two wavelengths simultaneously. The strength of
the line-of-sight component of the coronal magnetic field is inferred
from the measured amplitude of the Stokes V profile and an estimate of
the plane-of-sky direction is made from the Stokes U/Q ratio. Further,
inference of line-of-sight velocities can be made from Stokes I (red and
blue wing) amplitudes. Finally, it may be possible to obtain a coronal
density diagnostic capability from the ratio of the 1074.7/1079.8
amplitudes. This poster will present the latest test results as well
as any preliminary data that have been obtained.
---------------------------------------------------------
Title: Magnetic maps of prominences
Authors: Casini, R.; Lopez Ariste, A.; Tomczyk, S.; Lites, B.
2003AGUFMSH42D..05C Altcode:
We present the first magnetic maps of a prominence obtained by applying
our PCA inversion approach to prominence spectropolarimetric data
in the He I D3 line. Our results indicate the presence of organized
structures in the prominence plasma embedded in magnetic field that are
significantly larger than average (50 G and higher). We reaffirm the
need for a Hanle-based diagnostics of prominence magnetism using full
Stokes spectropolarimetry, and the importance of improved, multi-line
observations, ideally involving both He I D3 and 10830.
---------------------------------------------------------
Title: Magnetic Maps of Prominences from Full Stokes Analysis of
the He I D3 Line
Authors: Casini, R.; López Ariste, A.; Tomczyk, S.; Lites, B. W.
2003ApJ...598L..67C Altcode:
We present the first magnetic maps of a prominence, derived from
inversion of spectropolarimetric data in He I D3 using the principal
component analysis of all four Stokes profiles. This prominence,
along with several others, was observed in 2002 May using the Dunn
Solar Telescope of the National Solar Observatory/Sacramento Peak
Observatory, equipped with the High Altitude Observatory Advanced
Stokes Polarimeter. The use of an unocculted instrument allowed us to
map the prominence magnetic fields down to the chromospheric limb. Our
analysis indicates that the average magnetic field in prominences
is mostly horizontal and varies between 10 and 20 G, thus confirming
previous findings. However, our maps show that fields significantly
stronger than average, even as large as 60 or 70 G, can often be found
in clearly organized plasma structures of the prominence.
---------------------------------------------------------
Title: Study of p-mode excitation and damping rate variations from
IRIS<SUP>++</SUP> observations
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Tomczyk, S.
2003A&A...408..729S Altcode:
11 years of low degree helioseismic data collected by the
IRIS<SUP>++</SUP> network (International Research of the Interior of
the Sun) have been analyzed. The epoch covered (mid-1989 to end-1999)
spans the maximum and the falling phase of solar cycle 22 and the rising
phase of the current solar cycle 23. Annual timeseries with an overlap
of 6 months are used to study the variations with solar activity of
the p-mode frequencies nu <SUB>n,l</SUB>, heights H<SUB>n,l</SUB>,
and linewidths Gamma <SUB>n,l</SUB>, taking into account the effects of
the window function. These are used to infer variations in the velocity
power <V<SUB>n,l</SUB><SUP>2</SUP>> and the energy supply rate
dot E<SUB>n,l</SUB> which relate to changes in the excitation and
the damping of the modes. We find global changes over the range 2600
<= nu <= 3600 mu Hz of about -26%, 11%, -11% for the heights,
the linewidths, and the velocity power respectively, and a constant
energy supply to the modes.
---------------------------------------------------------
Title: Eleven years of IRIS frequencies and splittings
Authors: Fossat, E.; Salabert, David; Cacciani, A.; Ehgamberdiev,
S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.;
Palle, P.; Schmider, F. X.; Tomczyk, S.
2003ESASP.517..139F Altcode: 2003soho...12..139F
Having acquired since July, 1989, a complete 11-year solar cycle of
full disk data, the IRIS++ network has now made available to anyone the
longest helioseismic data base to-date. A few results obtained from this
very long time series are briefly presented here, with some emphasis
on the low degree p-mode frequencies themselves, and their rotational
splittings that have been estimated with unprecedented accuracy.
---------------------------------------------------------
Title: A first study of the excitation and damping rate variations
extracted from IRIS<SUP>++</SUP> observations
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Tomczyk, S.
2003ESASP.517..377S Altcode: 2003soho...12..377S
The IRIS<SUP>++</SUP> network (International Research of the Interior
of the Sun) have collected 11 years of low-l helioseismic data. Annual
time series with an overlapping of 6 months are used to study the
variations over the solar activity cycle of the different p-mode
parameters. We find a global change of about -26% in the amplitudes,
14% in the linewidth and -12% in the velocity power while the rate at
which the energy is supplied remains constant.
---------------------------------------------------------
Title: Polarimeter for the study of magnetic fields in prominences
Authors: Lopez Ariste, Arturo; Tomczyk, Steven; Semel, Meir;
Darnell, A.
2003SPIE.4853..235L Altcode:
We report on a new spectropolarimeter for the measurement of vector
magnetic fields on prominences using the HeD<SUB>3</SUB> line in the
Evans Solar Facility at the Sacramento Peak Observatory.
---------------------------------------------------------
Title: Hyperfine Structure as a Diagnostic Tool of Solar Magnetic
Fields
Authors: López Ariste, A.; Tomczyk, S.; Casini, R.
2003ASPC..307..115L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Helioseismic and Magnetic Imager (HMI) on SDO: Full Vector
Magnetography with a Filtergraph Polarimeter
Authors: Graham, J. D.; Norton, A.; López Ariste, A.; Lites, B.;
Socas-Navarro, H.; Tomczyk, S.
2003ASPC..307..131G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Vector Magnetic Field Measurement Capabiliity of the
Helioseismic and Magnetic Imager on SDO
Authors: Bush, R.; Scherrer, P.; Schou, J.; Liu, Y.; Tomczyk, S.;
Graham, J.; Norton, A.
2002AGUFMSH52A0464B Altcode:
The Helioseismic and Magnetic Imager (HMI) instrument has been selected
as part of the payload complement of the Solar Dynamics Observatory
Spacecraft. In this poster we describe the observing technique for
measuring solar vector magnetic fields. The expected performance of
the HMI instrument will be discussed including results of modeling
the observing lines and instrument.
---------------------------------------------------------
Title: Hyperfine Structure as a Diagnostic of Solar Magnetic Fields
Authors: López Ariste, A.; Tomczyk, S.; Casini, R.
2002ApJ...580..519L Altcode:
We propose the use of the Zeeman effect of the hyperfine structure
(HFS) as a diagnostic of solar photospheric magnetic fields. The HFS
induces unique signatures in the polarized spectra of particular atoms,
which can be used to directly get information on the magnetic field
strength. To explore the effects of HFS, we adopt a numerical model of
line formation and radiative transfer of polarized light in a magnetized
Milne-Eddington atmosphere. We concentrate our studies on several lines
of Mn I, which show particularly striking HFS signatures in the solar
atlas. For these lines, anomalous Stokes profiles are produced for
fields in the range 0-1000 G. The presence of these unusual profiles
for weak magnetic fields constitutes a novel and potentially powerful
diagnostic of the strength of solar magnetic fields in the quiet
photosphere and plages.
---------------------------------------------------------
Title: Spectroscopic Detection of the 3.934 Micron Line of Si IX in
the Solar Corona
Authors: Judge, P. G.; Tomczyk, S.; Livingston, W. C.; Keller, C. U.;
Penn, M. J.
2002ApJ...576L.157J Altcode:
We report the detection of the
2s<SUP>2</SUP>2p<SUP>2</SUP><SUP>3</SUP>P<SUB>1-->0</SUB> line of
Si IX using the McMath-Pierce telescope on Kitt Peak. Observations
were made of the solar disk and at various heights above the limb
between 2002 May 13 and 17, under nonideal sky conditions, using the
13.5 m vertical spectrograph and an InSb single-diode detector. We
report a new rest wavelength for the line and discuss its potential
use as a diagnostic of coronal magnetic fields using ground-based
telescopes. Our observations give λ<SUB>rest</SUB>=3.93434+/-0.00007
μm, consistent with earlier less accurate values, but it places the
blue wing of the line under a strong telluric N<SUB>2</SUB>O line. In
the active regions observed, the line's intensity is comparable to or
larger than predicted in earlier work for the quiet Sun.
---------------------------------------------------------
Title: Inference of Solar Magnetic Field Parameters from Data with
Limited Wavelength Sampling
Authors: Graham, Jonathan D.; López Ariste, Arturo; Socas-Navarro,
Hector; Tomczyk, Steven
2002SoPh..208..211G Altcode:
We investigate the diagnostic potential of polarimetric measurements
with filtergraph instruments. Numerical simulations are used to explore
the possibility of inferring the magnetic field vector, its filling
factor, and the thermodynamics of model atmospheres when only a few
wavelength measurements are available. These simulations assume the
magnetic Sun to be represented by Milne-Eddington atmospheres. The
results indicate that two wavelength measurements are insufficient
to reliably determine the magnetic parameters, regardless of whether
magnetograph techniques or least-squares fitting inversions are
used. However, as few as four measurements analyzed with the inversion
technique provide enough information to retrieve the intrinsic magnetic
field with an accuracy better than 10% in most cases.
---------------------------------------------------------
Title: IRIS<SUP>++</SUP> database: Merging of IRIS + Mark-1 + LOWL
Authors: Salabert, D.; Fossat, E.; Gelly, B.; Tomczyk, S.; Pallé, P.;
Jiménez-Reyes, S. J.; Cacciani, A.; Corbard, T.; Ehgamberdiev, S.;
Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.; Schmider, F. X.
2002A&A...390..717S Altcode:
The IRIS network has been operated continuously since July 1st
1989. To date, it has acquired more than a complete solar cycle
of full-disk helioseismic data which has been used to constrain
the structure and rotation of the deep solar interior. However,
the duty cycle of the network data has never reached initial
expectations. To improve this situation, several cooperations have
been developed with teams collecting observations with similar
instruments. This paper demonstrates that we are able to merge data
from these different instruments in a consistent manner resulting
in a very significant improvement in network duty cycle over more
than one solar cycle initiating what we call the IRIS<SUP>++</SUP>
network. The integrated radial velocities from the IRIS<SUP>++</SUP>
database (1989 to 1999) are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/717
---------------------------------------------------------
Title: Inference of Solar Vector Magnetic Fields with Filtergraph
Instruments
Authors: Graham, J. D.; Lites, B. W.; López Ariste, A.; Norton, A.;
Socas-Navarro, H.; Tomczyk, S.
2002AAS...200.5611G Altcode: 2002BAAS...34..736G
We investigate the diagnostic potential of polarimetric measurements
with filtergraph instruments. Numerical simulations are used to
explore the possibility of inferring the magnetic field vector, its
filling factor, and the thermodynamics of model atmospheres when
only a few wavelength measurements are available. The simulations
assume the magnetic sun to be represented by Milne-Eddington (ME)
atmospheres. The results indicate that two wavelength measurements
are insufficient to reliably determine the magnetic parameters,
regardless of whether magnetograph techniques or least-squares fitting
inversions are used. However, as few as four measurements analyzed
with the inversion technique provide enough information to retrieve the
intrinsic magnetic field with an accuracy better than 10 generated by
more general models and ASP data passed through a simulated filtergraph.
---------------------------------------------------------
Title: New Polarization Diagnostics for the Solar Atmosphere
Authors: Casini, R.; López Ariste, A.; Tomczyk, S.; Lites, B.
2002AAS...200.3403C Altcode: 2002BAAS...34..690C
We present relatively new diagnostics of “weak" magnetic fields in the
solar atmosphere. The first diagnostic is suggested by recent advances
in the inversion of Stokes profiles of lines formed by resonance
scattering in the weakly magnetized plasma of prominences (Hanle
effect and level-crossing; 0 to 100 G). Use of pattern recognition
techniques (PCA) in this field has marked a sensible progress with
respect to previous diagnostic procedures. The second diagnostic is
the modelling of hyperfine structured (HFS) lines that can be observed
in the spectrum of the quiet photosphere. This allows to investigate
relatively weak photospheric fields (200 G to 1000 G), in which regime
the HFS induces peculiar signatures in the Stokes profiles, including
the appearance of subcomponents and net circular polarization. The third
diagnostic is suggested by interesting polarization properties of the
Na I D1 line formed by resonance scattering: the atomic polarization
in the upper level of D1, which is responsible of a characteristic
antisymmetric (i.e., V-like) signature in the core of Stokes Q, is
rapidly suppressed for B > 10 G, irrespective of the magnetic field
direction. A common denominator of these three diagnostics is their
sensitivity to the actual strength of the magnetic field, instead
of the magnetic flux within the resolution element. Another common
aspect is that all require (or would profit from) high polarization
sensitivity, which will be one of the strengths of ATST. For the
diagnostics of prominence magnetic fields, the possibility of multiline
spectropolarimetry could be decisive. Simultaneous observations of
He I D3 (5876A) and 10830A, or of He I D3 and the Na I D lines (all
within a 20A spectral range!), would increase the inversion accuracy
of PCA. The high spatial resolution capabilities of ATST would be
advantageous mostly to diagnose weak photospheric fields, already at
the present time. Because of the complexity of radiative transfer in
complicated structures like prominences, high spatial resolution in
these structures is not the highest priority. However, we hope that
when ATST will become operative, this complicated problem will have
been attacked succesfully.
---------------------------------------------------------
Title: Analysis of variability of p-mode parameters in 11 years of
IRIS data
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Cacciani,
A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov,
S.; Lazrek, M.; Pallé, P.; Schmider, F. X.; Tomczyk, S.
2002ESASP.477..253S Altcode: 2002scsw.conf..253S
11 years of IRIS (the low degree helioseismology network) have been
analysed for the study of p-modes parameters variability. The duty
cycle of the network data has been improved by the partial gap filling
method named "repetitive music". This paper discusses the variations
of all p-modes parameters along these 11 years.
---------------------------------------------------------
Title: Analysis of the solar cycle and core rotation using 15 years
of Mark-I observations: 1984-1999 . I. The solar cycle
Authors: Jiménez-Reyes, S. J.; Corbard, T.; Pallé, P. L.; Roca
Cortés, T.; Tomczyk, S.
2001A&A...379..622J Altcode: 2001astro.ph.10364J
High quality observations of the low-degree acoustic modes
(p-modes) exist for almost two complete solar cycles using the solar
spectrophotometer Mark-I, located at the Observatorio del Teide
(Tenerife, Spain) and operating now as part of the Birmingham Solar
Oscillations Network (BiSON). We have performed a Fourier analysis of
30 calibrated time-series of one year duration covering a total period
of 15 years between 1984 and 1999. Applying different techniques to the
resulting power spectra, we study the signature of the solar activity
changes on the low-degree p-modes. We show that the variation of the
central frequencies and the total velocity power (TVP) changes. A
new method of simultaneous fit is developed and a special effort
has been made to study the frequency-dependence of the frequency
shift. The results confirm a variation of the central frequencies of
acoustic modes of about 0.45 mu Hz, peak-to-peak, on average for low
degree modes between 2.5 and 3.7 mHz. The TVP is anti-correlated with
the common activity indices with a decrease of about 20% between the
minimum and the maximum of solar cycle 22. The results are compared
with those obtained for intermediate degrees, using the LOWL data. The
frequency shift is found to increase with the degree with a weak
l-dependence similar to that of the inverse mode mass. This verifies
earlier suggestions that near surface effects are predominant.
---------------------------------------------------------
Title: Variations of the solar interior with the cycle: observational
aspects.
Authors: Corbard, Thierry; Jimenez-Reyes, S. J.; Thompson, M. J.;
Tomczyk, S.
2001sf2a.conf..109C Altcode:
Helioseismic observations of long duration now open the possibility of
studying the variation of the interior of the Sun during its cycle of
activity. In particular, the possible dynamic or structure variations of
the interface between the convective zone and the radiative interior,
or tachocline, is of great interest to constrain solar dynamo models
and to understand the phenomena at the origin of the cycle of activity
observed at the surface. We have analysed the observations obtained
during the 6 last years by the LOWL instrument located at Mauna Loa,
Hawaii as well as the observations in integrated disc covering more
than one solar cycle (1984-2000) by MARK-I instrument at the Peak del
Teide, Tenerife. The results concerning the signature of the solar
activity on the pressure modes of low and medium degrees and seeks for
possible variations of the dynamic of the tachocline will be presented
and replaced in the theoretical context.
---------------------------------------------------------
Title: Coronal Magnetometry: A Feasibility Study
Authors: Judge, P. G.; Casini, R.; Tomczyk, S.; Edwards, D. P.;
Francis, E.
2001STIN...0227999J Altcode:
Measurements of components of the vector magnetic field in the
solar corona can potentially yield information critical to our
understanding of coronal structure, dynamics and heating. In this
report we re-examine various techniques for such measurements,
in particular those that can be applied outside of active regions,
to investigate issues critical to the development of a new 'coronal
magnetometer,' and to lay down some foundations upon which a suitable
instrument may be developed for synoptic observations. The well-known
forbidden coronal emission lines of magnetic dipole (M1) character
appear to have the highest potential to address outstanding problems in
coronal physics, especially those related to the storage and release
of magnetic free energy. Measurements of the full Stokes vector of
M1 lines can constrain both the line-of-sight (LOS) field strength,
through the longitudinal Zeeman effect seen in Stokes V profiles, and
the direction of the vector field projected onto the plane-of-the-sky
(POS), through the analysis of resonance scattering-induced linear
polarization seen in Stokes Q and U, in the so-called 'strong field'
regime of the Hanl effect.
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Title: The solar tachocline and its variation (?)
Authors: Corbard, T.; Jiménez-Reyes, S. J.; Tomczyk, S.; Dikpati,
M.; Gilman, P.
2001ESASP.464..265C Altcode: 2001soho...10..265C; 2000astro.ph.11367C
The solar tachocline, located at the interface between the
latitude-dependent rotation of the convection zone and the rigid
radiative interior, presents high gradients of angular velocity
which are of particular interest for the models of the solar dynamo
and angular momentum transport. Furthermore, latitudinal and temporal
variations of the tachocline parameters, if any, are also of particular
interest in order to constrain models. We present a review of some of
the theories of the tachocline and their predictions that may be tested
by helioseismology. We describe the methods for inferring the tachocline
parameters from obervations and the associated difficulties. A review of
results previously obtained is given and an analysis of the new 6 years
database of LOWL observations is presented which yields no compelling
evidence of variations or general trend of the tachocline parameters
during the ascending phase of the current solar cycle (1994-2000).
---------------------------------------------------------
Title: Calibration procedure for the polarimetric instrument for
Solar Eclipse-98
Authors: Elmore, David F.; Card, G. L.; Lecinski, A. R.; Lites,
Bruce W.; Streander, Kim V.; Tomczyk, Steven
2000SPIE.4139..370E Altcode:
We describe a ground-based eclipse instrument for measuring solar
coronal polarization brightness and intensity, and the calibration
procedures for this instrument. We present coronal measurements from the
February 26, 1998 total solar eclipse observed at Curacao, N.A.. The
instrument employs a liquid crystal variable retarder for analysis of
coronal broad band linear polarization and collects data on an array
detector spanning a 6.5 solar radius field of view. Polarization
calibration of the liquid crystal variable retarder utilizes the
tangential orientation of coronal polarization to calculate retardance
values.
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Title: A New Precise Measurement of the Coronal Magnetic Field
Strength
Authors: Lin, Haosheng; Penn, Matthew J.; Tomczyk, Steven
2000ApJ...541L..83L Altcode:
Magnetism dominates the structure and dynamics of the solar
corona. Current theories suggest that it may also be responsible for
coronal heating. Despite the importance of the magnetic field in the
physics of the corona and despite the tremendous progress made recently
in the remote sensing of solar magnetic fields, reliable measurements of
the coronal magnetic field strength and orientation do not exist. This
is largely due to the weakness of coronal magnetic fields, previously
estimated to be on the order of 10 G, and the difficulty associated
with observing the extremely faint solar corona emission. Using a
very sensitive infrared spectropolarimeter to observe the strong
near-infrared coronal emission line Fe XIII λ10747 above active
regions, we have succeeded in measuring the weak Stokes V circular
polarization profiles resulting from the longitudinal Zeeman effect
of the magnetic field of the solar corona. From these measurements,
we infer field strengths of 10 and 33 G from two active regions at
heights of h=0.12 R<SUB>solar</SUB> and h=0.15 R<SUB>solar</SUB>,
respectively. We expect that this measurement technique will allow,
in the near future, the routine precise measurement of the coronal
magnetic field strength with application to many critical problems in
solar coronal physics.
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Title: Solar cycle variations of oscillation mode parameters from
LOWL and MARK-I instruments
Authors: Jimeńez Reyes, S. J.; Corbard, T.; Tomczyk, S.; Pallé, P. L.
2000SPD....31.0112J Altcode: 2000BAAS...32.1289J
The signature of the Solar-Cycle appears clearly in the p-mode
parameters (Jiménez-Reyes et al. 1998, Libbrecht & Woodard 1990,
and Anguera et al. 1992). At present, the study of the p-mode parameter
variation is a very active topic in helioseismology where, thanks to
projects like BISON, IRIS, GONG, LOWL and MDI, we are able for the first
time to analyse, using heliosismology, how the Sun internal structure
and dynamic change over the magnetic cycle. High-quality observations
for low degree p-modes have been accumulated for more than twenty years
using the solar spectro photometer MARK-I, located and operating at the
Observatorio del Teide (Tenerife, Spain). The data-base available have
been re-analyzed over a much wider time interval than before. Moreover,
the LOWL instrument, a Potassium Magneto-Optical Filter, located at the
Manua Loa Observatory, has been measuring for more than six years solar
oscillations of intermadiate p-mode degree. The data-base represents
one of the best available to analyze the influence of the Solar-Cycle
on the mode parameters, mainly because these data, concerning both low
and intermadiate degree modes, give us information over an extensive
range of the solar depths which may allow us to locate characteristics
of the solar dynamo process. Using different data sets and different
techniques, we analyse the behaviour of the solar p-modes in an attempt
to better understand the origin of the Solar-Cycle.
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Title: The ECHO (Experiment for Coordinated Helioseismic Observations)
Network
Authors: Tomczyk, S.; Jiménez Reyes, S. J.; Jiménez, A.; Pallé,
P. L.
2000SPD....31.0117T Altcode: 2000BAAS...32..804T
The High Altitude Observatory of the National Center for Atmospheric
Research (HAO/NCAR) in collaboration with the Instituto de Astrofísica
de Canarias (IAC) have recently completed a two-station helioseismic
network with sites at Mauna Loa, Hawaii and Izana, Tenerife. The
instruments are Doppler imagers employing Magneto-Optical filters and
are based on the existing LOWL instrument. We expect the network to
provide a duty cycle of 50%, compared to 22% for the LOWL. In addition,
the ECHO incorporates several improvements over the LOWL including:
1) a CCD detector with square pixels and a factor of two increase
in spatial resolution; 2) better guiding; 3) exchange of red and blue
images every 15 seconds to better facilitate detector flat fielding; and
4) improved thermal control of the instrument enclosure. We will present
initial data from the network and demonstrate network performance.
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Title: Solar rotation From GOLF/LOWL
Authors: Corbard, T.; Jiménez Reyes, S. J.; Tomczyk, S.; GOLF Team
2000SPD....31.0102C Altcode: 2000BAAS...32..801C
The solar core rotation is an important open question that can be
addressed by using observations from the spacecraft SOHO and ground
based instruments. In particular, GOLF experiment on board SoHO
is dedicated to the observation of low-degree oscillations which
penetrate the solar core and it has been operating for more than three
years. Similarly, LOWL instrument has been collecting data from ground
for both low and intermediate degrees for more than 6 years. It is now
well established that the differential rotation observed at the surface
persists in the convection zone and become mainly solid in the radiative
interior through a transition zone called the tachocline. Nevertheless
it is still controversial to know if the core is rotationg slower,
faster or at the same rate than the radiative interior. We use new
data acquired during the last years and recently analysed from GOLF
and LOWL in order to give an up to date status of our knowledge on
the solar core rotation.
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Title: p-mode Frequency Shift as Solar Activity Index
Authors: Jiménez-Reyes, S. J.; Corbard, Thierry; Palle, Pere L.;
Tomczyk
2000ESASP.463..341J Altcode: 2000sctc.proc..341J
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of polar plumes observed at the 1998 February
26 eclipse
Authors: Lites, B. W.; Card, G.; Elmore, D. F.; Holzer, T.; Lecinski,
A.; Streander, K. V.; Tomczyk, S.; Gurman, J. B.
1999SoPh..190..185L Altcode:
This paper presents first observations of dynamics of the white-light
solar corona detected during the few minutes of totality of a solar
eclipse. Perturbations of a polar plume associated with an embedded
`jet' structure observed simultaneously at 195 Å with the EUV
Imaging Telescope (EIT) aboard the SOHO spacecraft lead to estimates
of the electron density fluctuations accompanying the jet: ±15%. The
morphological behavior of the jet, its apparent upward propagation speed
of ≈200 km s<SUP>−1</SUP>, and the inferred density perturbations
suggest that the jet is led by a weak, outward-propagating shock
resulting from the injection of material at high velocity at the base of
the corona. Smaller perturbations of the white-light corona are apparent
at many other locations, sustaining hope that propagating Alfvén waves
may be measurable in the solar corona. Density perturbations associated
with the jet follow from empirical electron density models of the polar
inter-plume and plume regions, as derived from the ground-based eclipse
measurements of coronal polarization brightness. These models indicate
polar plume densities 4-6 times that of the interplume low corona.
---------------------------------------------------------
Title: Helioseismic Constraints on the Structure of the Solar
Tachocline
Authors: Charbonneau, P.; Christensen-Dalsgaard, J.; Henning, R.;
Larsen, R. M.; Schou, J.; Thompson, M. J.; Tomczyk, S.
1999ApJ...527..445C Altcode:
This paper presents a series of helioseismic inversions aimed at
determining with the highest possible confidence and accuracy the
structure of the rotational shear layer (the tachocline) located
beneath the base of the solar convective envelope. We are particularly
interested in identifying features of the inversions that are robust
properties of the data, in the sense of not being overly influenced
by the choice of analysis methods. Toward this aim we carry out
two types of two-dimensional linear inversions, namely Regularized
Least-Squares (RLS) and Subtractive Optimally Localized Averages
(SOLA), the latter formulated in terms of either the rotation rate or
its radial gradient. We also perform nonlinear parametric least-squares
fits using a genetic algorithm-based forward modeling technique. The
sensitivity of each method is thoroughly tested on synthetic data. The
three methods are then used on the LOWL 2 yr frequency-splitting
data set. The tachocline is found to have an equatorial thickness
of w/R<SUB>solar</SUB>=0.039+/-0.013 and equatorial central radius
r<SUB>c</SUB>/R<SUB>solar</SUB>=0.693+/-0.002. All three techniques
also indicate that the tachocline is prolate, with a difference in
central radius Δr<SUB>c</SUB>/R<SUB>solar</SUB>~=0.024+/-0.004 between
latitude 60° and the equator. Assuming uncorrelated and normally
distributed errors, a strictly spherical tachocline can be rejected
at the 99% confidence level. No statistically significant variation
in tachocline thickness with latitude is found. Implications of these
results for hydrodynamical and magnetohydrodynamical models of the
solar tachocline are discussed.
---------------------------------------------------------
Title: Rotation of the solar core from BiSON and LOWL frequency
observations
Authors: Chaplin, W. J.; Christensen-Dalsgaard, J.; Elsworth, Y.;
Howe, R.; Isaak, G. R.; Larsen, R. M.; New, R.; Schou, J.; Thompson,
M. J.; Tomczyk, S.
1999MNRAS.308..405C Altcode:
Determination of the rotation of the solar core requires very accurate
data on splittings for the low-degree modes which penetrate to the core,
as well as for modes of higher degree to suppress the contributions
from the rest of the Sun to the splittings of the low-degree modes. Here
we combine low-degree data based on 32 months of observations with the
BiSON network and data from the LOWL instrument. The data are analysed
with a technique that specifically aims at obtaining an inference of
rotation that is localized to the core. Our analysis provides what we
believe is the most stringent constraint to date on the rotation of
the deep solar interior.
---------------------------------------------------------
Title: The Rotation of the Solar Core Inferred by Genetic Forward
Modeling
Authors: Charbonneau, P.; Tomczyk, S.; Schou, J.; Thompson, M. J.
1998ApJ...496.1015C Altcode:
Genetic forward modeling is a genetic algorithm-based modeling technique
that can be used to perform helioseismic inversions of the Sun's
internal angular velocity profile. The method can easily accommodate
constraints such as positivity and monotonicity and readily lends itself
to the use of robust statistical goodness-of-fit estimators. After
briefly describing the technique, we ascertain its performance
by carrying out a series of inversions for artificial splitting
data generated from a set of synthetic internal rotation profiles
characterized by various small inward increases in angular velocity in
the deep solar core (r/R<SUB>⊙</SUB> <= 0.5). These experiments
indicate that the technique is accurate down to r/R<SUB>⊙</SUB>
~= 0.2, and retains useful sensitivity down to r/R<SUB>⊙</SUB> ~=
0.1. <P />We then use genetic forward modeling in conjunction with the
LOW degree L (LOWL) 2 year frequency-splitting data set to determine
the rotation rate in the deep solar core. We perform a large set
of one-dimensional and 1.5-dimensional inversions using regularized
least-squares minimization, conventional least-squares minimization
with a monotonicity constraint (∂Ω/∂r <= 0), and inversions
using robust statistical estimators. These calculations indicate that
the solar core rotates very nearly rigidly down to r/R<SUB>⊙</SUB> ~
0.1. More specifically, on spatial scales >~0.04 R<SUB>⊙</SUB> we
can rule out inward increases by more than 50% down to r/R<SUB>⊙</SUB>
= 0.2, and by more than a factor of 2 down to r/R<SUB>⊙</SUB> =
0.1. Thorough testing of various possible sources of bias associated
with our technique indicates that these results are robust with respect
to intrinsic modeling assumptions. Consequences of our results for
models of the rotational evolution of the Sun and solar-type stars
are discussed.
---------------------------------------------------------
Title: Solar internal sound speed as inferred from combined BiSON
and LOWL oscillation frequencies
Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Chaplin, W. J.;
Elsworth, Y.; Isaak, G. R.; New, R.; Schou, J.; Thompson, M. J.;
Tomczyk, S.
1997MNRAS.292..243B Altcode: 1997astro.ph..2105B
Observations of the Sun with the LOWL instrument provide a homogeneous
set of solar p-mode frequencies from low to intermediate degree that
allow one to determine the structure of much of the solar interior
avoiding systematic errors that are introduced when different data sets
are combined, i.e., principally the effects of solar cycle changes on
the frequencies. Unfortunately, the LOWL data set contains very few of
the lowest-degree modes, which are essential for determining reliably
the structure of the solar core - in addition, these lowest-degree data
have fairly large associated uncertainties. However, observations made
by the Birmingham Solar-Oscillations Network (BiSON) in integrated
sunlight provide high-accuracy measurements of a large number of
low-degree modes. In this paper we demonstrate that the low-degree mode
set of the LOWL data can be successfully combined with the more accurate
BiSON data, provided the observations are contemporaneous for those
frequencies where the solar cycle induced effects are important. We
show that this leads to a factor of 2 decrease in the error on the
inferred sound speed in the solar core. We find that the solar sound
speed is higher than in solar models for r<0.2Rsolar. The density
of the solar core is, however, lower than that in solar models.
---------------------------------------------------------
Title: Solar internal rotation from LOWL data. A 2D regularized
least-squares inversion using B-splines.
Authors: Corbard, T.; Berthomieu, G.; Morel, P.; Provost, J.; Schou,
J.; Tomczyk, S.
1997A&A...324..298C Altcode:
Observations of surface oscillations of the Sun can be analyzed to
probe the solar interior. We use data obtained by the LOWL instrument
(LOWL is an abbreviation for low degree with degree denoted by L)
installed on Mauna Loa, Hawaii, since 1994 to investigate solar
internal rotation. A 2 Dimensional Regularized Least-Squares (2D RLS)
inverse method based on an expansion of the solution on B-splines of
arbitrary order is presented and applied to a 2 year dataset. This
method insures the regularity of the solution in the center and
introduces surface constraints. The choice of trade-off parameters in
the regularization term is discussed using an L-curves analysis and
we discuss the influence of the choice of the order of derivatives in
the regularization terms for the description of the deep interior. We
study the latitudinal resolution of the inversion of a-coefficients
compared to that of the inversion of individual splittings built from
these coefficients. Compared to the previous inversion of the first
three months of LOWL data made by Tomczyk et al. (1995ApJ...448L..57T),
our solution is extended up to the surface by adding high degree modes
and constraining the rotation to fit the spectrographic observations
(Snodgrass, 1984SPh....94...13S). In the radiative zone we obtain
more rigid rotation and our solution is compatible with a rotation of
the solar core of the order or smaller than the surface rotation at
mid latitude.
---------------------------------------------------------
Title: Stokes Profile Asymmetries in Solar Active Regions
Authors: Balasubramaniam, K. S.; Keil, S. L.; Tomczyk, S.
1997ApJ...482.1065B Altcode:
Asymmetries in Stokes polarization spectral line profiles can be
attributed to the existence of gradients in the velocity (and magnetic
field) over the line-forming region. Models that solve the Stokes
radiative transfer equations have incorporated both line-of-sight
gradients and gradients perpendicular to the line of sight over the
resolution element to produce the observed asymmetries. There have been
only a few systematic studies of how these Stokes profile asymmetries
vary across spatial structures and as a function of the amplitude of the
velocity and magnetic fields, and very little statistical information
is available. We present observational results from high spectral and
spatial resolution Stokes V profile measurements made in an active
region located near disk center and present correlations between the
amplitude of the Stokes V asymmetry, the magnetic field strength, and
line shifts and line asymmetries observed in the Stokes I profile. In
regions where the field strength exceeds a few hundred gauss, we find
a good correlation between the amplitude of the measured asymmetry
in Stokes V and the observed shifts of the Stokes I profile. We also
find a correlation between the asymmetry of the Stokes I profile and
the amplitude of the Stokes V profile asymmetry.
---------------------------------------------------------
Title: Helioseismology by Genetic Forward Modeling
Authors: Charbonneau, P.; Tomczyk, S.
1997ASPC..123...49C Altcode: 1997taca.conf...49C
No abstract at ADS
---------------------------------------------------------
Title: Solar structure as revealed by 1 year LOWL data
Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Schou, J.; Thompson,
M. J.; Tomczyk, S.
1996BASI...24..147B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Results from the LOWL instrument
Authors: Schou, J.; Tomczyk, S.; Thompson, M. J.
1996BASI...24..375S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Low-degree frequency splitting measurements and the rotation
rate of the solar core
Authors: Tomczyk, S.; Schou, J.; Thompson, M. J.
1996BASI...24..245T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Measurement of the Rotation Rate in the Deep Solar Interior
Authors: Tomczyk, S.; Schou, J.; Thompson, M. J.
1996AAS...188.6903T Altcode: 1996BAAS...28..935T
We present a measurement of the rotation rate in the interior of the
Sun based on two years of observations with the LOWL instrument. LOWL
allows the observation of solar oscillations with degrees from 0
to 100, thus providing a homogeneous low- and intermediate-degree
dataset. Significantly, it is able to make spatially resolved
observations of low degree modes, thereby making it possible to separate
the different modes within a given multiplet. This reduces the potential
for systematic errors compared to observations using integrated
sunlight. We have used observations of the frequency splittings
of modes with degrees from 1 to 100 to infer the rotation rate in
the solar interior with some radial resolution and without excessive
errors. Over most of the interior we have also been able to estimate
the latitudinal variation of the rotation rate. We confirm earlier
findings that near the base of the convection zone the solar rotation
profile undergoes a transition from surface-like differential rotation
to a rotation rate that is independent of latitude. Additionally,
we find that below the base of the convection zone our measurement is
consistent with rigid body rotation at a rate somewhat lower than the
surface equatorial rate. This measurement provides strong constraints
on the theories of angular momentum transport in solar-type stars.
---------------------------------------------------------
Title: GONG Data: Implications for the Sun's Interior and Near
Surface Magnetic Field
Authors: Goode, P. R.; Dziembowski, W. A.; Rhodes, E. J., Jr.; Tomczyk,
S.; Schou, J.; GONG Magnetic Effects Team
1996AAS...188.5307G Altcode: 1996BAAS...28..904G
The solar oscillation spectrum and the fine structure in it from the
first complete month of GONG data have been used to place a limit
on the Sun's internal magnetic field. The limit is consistent with
the magnetic pressure being no more than 1/1000 of the gas pressure
between the Sun's deep interior and its surface. This conclusion is
consistent with earlier results. The GONG data are from a time near
magnetic activity minimum. The effect of the near surface magnetic
field on the fine structure in the oscillation spectrum reflects
a perturbation of quadrupole toroidal symmetry. This geometry also
dominated at the last activity minimum. The meaning of this result is
discussed. The near surface magnetic perturbation is not spherically
symmetric. This corrupts the results of inversions designed to probe
the Sun's deep interior. The solution to this problem is presented.
---------------------------------------------------------
Title: White Light Coronal Rotation Characteristics: 1984-1995
Authors: Hassler, D. M.; Tomczyk, S.
1996AAS...188.8006H Altcode: 1996BAAS...28..957H
Time series of white light polarized brightness (pB) data from the HAO
MkIII K-coronameter at Mauna Loa, Hawaii have been analyzed by direct
Fourier analysis to study variations in the coronal rotation rate as
a function of height, latitude, and time in the solar cycle. Short
time series (ranging from 1-4 years) provide the ability to resolve or
discriminate variations in the rotation rate at different times in the
solar cycle while longer time series (i.e. 12 years) provide maximum
signal-to-noise to study variations of rotation rate with height in
the corona. Results suggest evidence of variations of the rotation
rate with latitude and height, with more differential rotation and
slightly faster mean rotation rates present at lower heights in the
corona. Results also suggest variations of differential rotation and
mean rotation rate with time in the solar cycle with slightly faster
rotation rates during solar minimum.
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Title: The Solar Acoustic Spectrum and Eigenmode Parameters
Authors: Hill, F.; Stark, P. B.; Stebbins, R. T.; Anderson, E. R.;
Antia, H. M.; Brown, T. M.; Duvall, T. L., Jr.; Haber, D. A.;
Harvey, J. W.; Hathaway, D. H.; Howe, R.; Hubbard, R. P.; Jones,
H. P.; Kennedy, J. R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher,
J. W.; Libbrecht, K. G.; Pintar, J. A.; Rhodes, E. J., Jr.; Schou, J.;
Thompson, M. J.; Tomczyk, S.; Toner, C. G.; Toussaint, R.; Williams,
W. E.
1996Sci...272.1292H Altcode:
The Global Oscillation Network Group (GONG) project estimates
the frequencies, amplitudes, and linewidths of more than 250,000
acoustic resonances of the sun from data sets lasting 36 days. The
frequency resolution of a single data set is 0.321 microhertz. For
frequencies averaged over the azimuthal order m, the median formal
error is 0.044 microhertz, and the associated median fractional error
is 1.6 x 10<SUP>-5</SUP>. For a 3-year data set, the fractional error
is expected to be 3 x 10<SUP>-6</SUP>. The GONG m-averaged frequency
measurements differ from other helioseismic data sets by 0.03 to 0.08
microhertz. The differences arise from a combination of systematic
errors, random errors, and possible changes in solar structure.
---------------------------------------------------------
Title: The Sun's Hydrostatic Structure from LOWL Data
Authors: Basu, Sarbani; Christensen-Dalsgaard, J.; Schou, J.; Thompson,
M. J.; Tomczyk, S.
1996ApJ...460.1064B Altcode:
Recent observations with the LOWL (Low-Degree [l] Oscillations
Experiment) instrument have for the first time provided a uniform set of
frequencies that allow detailed inversion for the structure of much of
the Sun's deep interior. We present the results of inverting the LOWL
data and compare them with the corresponding results obtained using
inhomogeneous data sets from more than one instrument. Furthermore,
improvements in the description of the required physics motivates the
calculation of new solar models. Thus, we present results of inversions
of the LOWL data against several reference models using up-to-date
physics. In models including the gravitational settling of helium, the
sound speed and density agree with the Sun to within substantially
better than 1%. We test various modifications to the physics of
the models in order to see if the remaining small (but significant)
discrepancy between the Sun and the models can be removed. We find
that none of the modifications tested can adequately account for the
remaining discrepancy, though a small increase in helium diffusion
in the core gives a modest improvement over the standard diffusion
model. Finally, we find that the seismic data support theoretical
calculations that indicate that settling of heavier elements has
reduced the present surface value of Z by about 8% relative to its
mean interior value.
---------------------------------------------------------
Title: Results From the LOWL Instrument
Authors: Schou, J.; Tomczyk, S.; Thompson, M. J.
1995AAS...18710101S Altcode: 1995BAAS...27.1426S
In this poster we will present various results from one year of
observations with the LOWL instrument. The LOWL instrument is designed
to observe oscillations with degrees l from 0 to about 100 providing a
homogeneous dataset for inversions. Given the spatial resolution of the
instrument it is possible to separate different azimuthal orders m even
for the lowest degree modes, hopefully giving more accurate splittings
than those determined using integrated sunlight for a similar time
period. We will show the results of an inversion for the solar rotation
rate between 0.1R_sun and 0.95R_sun. Given the long duration and the
large number of terms used to describe the m-dependence of the mode
frequencies we have been able to obtain very good resolution in both
the radial direction and in latitude while keeping the statistical
errors low, thereby obtaining more accurate results than previously
possible. We will also present results of analyzing different parts of
the time-series and compare the temporal variations in mode frequencies
and splittings with variations in the solar activity.
---------------------------------------------------------
Title: Measurement of the Rotation Rate in the Deep Solar Interior
Authors: Tomczyk, S.; Schou, J.; Thompson, M. J.
1995ApJ...448L..57T Altcode:
We present a measurement of solar internal rotation based
on observations obtained over 3 months in early 1994 with a new
instrument called LOWL. This instrument allows for the simultaneous
observation of low- and intermediate-degree solar oscillations with
spatial resolution. We have measured the frequency splitting of 673
multiplets with degrees ranging from 1 to 80 and inverted these to
derive an estimate of the solar internal rotation profile between 0.2
and 0.85 R⊙. The accuracy of this measurement ranges from ~1% in the
outer regions to ~5% at 0.2 R⊙ and thus places better constraints than
hitherto on the rotation in the deep solar interior. We confirm earlier
findings that near the base of the convection zone the solar rotation
profile undergoes a transition from surface-like differential rotation
to a rotation rate that is independent of latitude. In addition, we
find that from the base of the convection zone down to 0.2 R⊙ our
measurement is consistent with rigid body rotation at a rate somewhat
lower than the surface equatorial rate. The accuracy of our measurement
in the deep solar interior provides a strong constraint to theories
of solar and stellar angular momentum transport.
---------------------------------------------------------
Title: A Measurement of the Rotation Rate in the Deep Solar Interior
Authors: Schou, J.; Tomczyk, S.; Thompson, M. J.
1995ESASP.376b.275S Altcode: 1995soho....2..275S; 1995help.confP.275S
No abstract at ADS
---------------------------------------------------------
Title: Solar Structure Inversion with LOWL Data
Authors: Basu, S.; Christensen-Dalsgaard, J.; Schou, J.; Thompson,
M. J.; Tomczyk, S.
1995ESASP.376b..25B Altcode: 1995help.confP..25B; 1995soho....2...25B
Presents inversion results for the radial hydrostatic structure of
the Sun, using six months of oscillation data obtained with the LOWL
instrument. Using modes with degrees from 0 to 90 and frequencies
between 1.5 and 3.5 mHz, the authors have inferred the variation with
depth of the sound speed, density ρ and u = p/ρ (p being pressure)
from r = 0.05 R<SUB>sun</SUB> to 0.85 R<SUB>sun</SUB>. They find that
in this region the sound speed in the Sun is within 0.15% of that of a
model constructed using the MHD equation of state and OPAL opacities
and incorporating helium diffusion. The density difference between
Sun and model is less than 0.8%. Given the small error bars on the
inversion results these small differences are significant, however. The
solar sound speed appears to be higher than in the model for r <
0.2 R<SUB>sun</SUB> . The authors speculate that this might indicate
interesting physics in the inner core.
---------------------------------------------------------
Title: Constraining Solar Core Rotation with Genetic Forward Modelling
Authors: Tomczyk, S.; Charbonneau, P.; Schou, J.; Thompson, M. J.
1995ESASP.376b.271T Altcode: 1995soho....2..271T; 1995help.confP.271T
No abstract at ADS
---------------------------------------------------------
Title: An Instrument to Observe Low-Degree Solar Oscillations
Authors: Tomczyk, S.; Streander, K.; Card, G.; Elmore, D.; Hull, H.;
Cacciani, A.
1995SoPh..159....1T Altcode:
We have constructed an instrument optimized to observe solar
oscillations of low degree. The primary goal of this instrument,
which we call LOWL, is to measure the frequency splitting of the
low-degree modes in order to determine the rotation rate of the solar
core. The LOWL is a Doppler imager based on a magneto-optical filter. It
employs a two-beam technique to simultaneously observe solar images in
opposite wings of the absorption line of potassium at 769.9 nm. This
instrument is very stable against drifts in the wavelength zero-point,
is insensitive to noise sources due to intensity fluctuations and image
motion, and has a Doppler analyzer with no moving parts. The LOWL has
been deployed at HAO's observing station on Mauna Loa, Hawaii and will
operate for a period of at least two years.
---------------------------------------------------------
Title: Stokes Profile Asymmetries in Active Regions
Authors: Balasubramaniam, K. S.; Keil, S. L.; Tomczyk, S.; Bernasconi,
P.
1995SPD....26..205B Altcode: 1995BAAS...27..951B
No abstract at ADS
---------------------------------------------------------
Title: Results from the LOWL Instrument
Authors: Schou, J.; Tomczyk, S.; Thompson, M. J.
1995SPD....26..402S Altcode: 1995BAAS...27..954S
No abstract at ADS
---------------------------------------------------------
Title: Spatially Resolved Observations of Low-Degree Solar
Oscillations
Authors: Tomczyk, S.
1995ASPC...76..444T Altcode: 1995gong.conf..444T
No abstract at ADS
---------------------------------------------------------
Title: Preliminary Results from Observations with the LOWL Instrument
Authors: Schou, J.; Tomczyk, S.
1995ASPC...76..448S Altcode: 1995gong.conf..448S
No abstract at ADS
---------------------------------------------------------
Title: A Measurement of the Rotation Rate in the Deep Solar Interior
Authors: Schou, J.; Tomczyk, S.; Thompson, M. J.
1994AAS...185.4401S Altcode: 1994BAAS...26Q1377S
Measurements of the rotation rate in the deep solar interior using
helioseismology have given inconsistent results, presumably due to
problems with the algorithms used for the analysis of spatially
unresolved observations of the oscillations. Here we present a
measurement of the rotation rate in the interior of the Sun based
on observations with a new instrument called LOWL. Unlike earlier
instruments this instrument allows the observation of oscillations
with degrees from 0 to ~ 80. In particular it is able to make spatially
resolved observations of low degree modes, thereby making it possible to
spatially separate the different modes within a given multiplet. This
reduces the potential for systematic errors compared to observations
using integrated sunlight. We have used observations of the frequency
splittings of modes with degrees from 1 to 80 to infer the rotation rate
in the solar interior down to ~ 0.2 R_⊙ with some radial resolution
and without excessive errors. Over part of the range we have also been
able to estimate the latitudinal variation of the rotation rate. This
measurement provides strong constraints on the theories of solar and
stellar angular momentum transport.
---------------------------------------------------------
Title: Simultaneous Filter and Spectrograph Observations of Active
Regions with the Advanced Stokes Polarimeter
Authors: Tomczyk, S.; Balasubramaniam, K. S.; Keil, Stephen L.
1994ASPC...68..262T Altcode: 1994sare.conf..262T
No abstract at ADS
---------------------------------------------------------
Title: Requirements for the Observation of Low-Degree Solar
Oscillations
Authors: Veitzer, S. A.; Tomczyk, S.; Schou, J.
1993ASPC...42..465V Altcode: 1993gong.conf..465V
No abstract at ADS
---------------------------------------------------------
Title: Early Results from HAO/NSO Advanced Stokes Polarimeter
Authors: Lites, B. W.; Elmore, D. F.; Tomczyk, S.; Seagraves, P.;
Skumanich, A.; Streander, K. V.
1993ASPC...46..173L Altcode: 1993mvfs.conf..173L; 1993IAUCo.141..173L
No abstract at ADS
---------------------------------------------------------
Title: LOWL - an Instrument to Observe Low-Degree Solar Oscillations
Authors: Tomczyk, S.; Cacciani, A.; Veitzer, S. A.
1993ASPC...42..469T Altcode: 1993gong.conf..469T
No abstract at ADS
---------------------------------------------------------
Title: The Advanced Stokes Polarimeter - A new instrument for solar
magnetic field research
Authors: Elmore, D. F.; Lites, B. W.; Tomczyk, S.; Skumanich,
A. P.; Dunn, R. B.; Schuenke, J. A.; Streander, K. V.; Leach, T. W.;
Chambellan, C. W.; Hull, H. K.
1992SPIE.1746...22E Altcode:
A new Stokes polarimeter for high spatial resolution quantitative
measurement of magnetic fields at multiple heights in the solar
atmosphere has been constructed by the National Center for Atmospheric
Research and the National Solar Observatory. The instrument uses
the Vacuum Tower Telescope at Sunspot, New Mexico, and its existing
horizontal spectrograph, universal birefringment filter, and image
motion stabilization system. The polarimeter uses a rotating retarder
polarization modulator with polarization calibration optics. Multiple
paired CCDs are used for detection followed by video processing to
produce spatial maps of the full state of polarization in restricted
regions of the solar spectrum. Two spectral regions encompassing
lines sensitive to the Zeeman effect, which form in the photosphere
and low chromosphere, are recorded simultaneously. Significant
developments include: construction of the new telescope post
focus optical arrangement, creation of a polarization model for the
telescope, construction of high-speed, low-noise solid state cameras,
and construction of computer hardware for receiving and processing
high-rate 12-bit digital data.
---------------------------------------------------------
Title: The Advanced Stokes Polarimeter: A New Instrument for Solar
Magnetic Field Research
Authors: Tomczyk, S.; Elmore, D. F.; Lites, B. W.; Dunn, R. B.;
Skumanich, A.; Schuenke, J. A.; Streander, K. V.; Leach, T. W.;
Chambellan, C. W.; Lacey, L. B.
1992AAS...180.5108T Altcode: 1992BAAS...24..814T
A new Stokes polarimeter for high spatial resolution quantitative
measurement of magnetic fields at multiple heights in the solar
atmosphere has been constructed by the National Center for Atmospheric
Research and the National Solar Observatory. The instrument has become
operational at the Vacuum Tower Telescope at Sunspot, New Mexico
and uses its existing horizontal spectrograph, universal birefringent
filter, and image motion stabilization system. To these optical systems
we have added a rotating wave plate polarimeter and polarization
calibration optics. Multiple CCDs are used for detection followed by
video processing in order to produce polarization maps of solar regions
from several spectrum lines simultaneously. Significant developments
include: a) construction of the new VTT post focus optical arrangement,
b) creation of a polarization model for the VTT, c) construction of
high speed, low noise CCD cameras, and d) construction of computer
hardware for receiving and processing high rate 12-bit digital data.
---------------------------------------------------------
Title: First Results from the Advanced Stokes Polarimeter
Authors: Lites, B. W.; Dunn, R. B.; Elmore, D. F.; Tomczyk, S.;
Skumanich, A.; Streander, K. V.
1992AAS...180.1201L Altcode: 1992BAAS...24..747L
The Advanced Stokes Polarimeter (ASP) is a collaborative program between
the High Altitude Observatory (HAO) and the National Solar Observatory
(NSO) to investigate the physics of solar active regions though
quantitative measurements of vector magnetic fields. First scientific
results from the ASP were obtained during an observing run in March,
1992, when high resolution Stokes profile maps of active regions were
obtained under good seeing conditions. The ASP measures simultaneously
the full Stokes profiles in photospheric Fe I lines near 630 nm and in
the temperature minimum/low chromospheric Mg I b-lines at 517 nm. We
present scans of an isolated small sunspot near disk center, and we
discuss the fine structure of the vector field within this sunspot
and in the magnetic elements surrounding it. Observations of a complex
active region near the east limb will also be presented. This active
region produced a flare during the observational sequence.
---------------------------------------------------------
Title: Systematic errors in polarimeter calibration due to imperfect
calibration optics.
Authors: Tomczyk, S.; Stoltz, P.; Seagraves, P.
1991sopo.work..142T Altcode:
The authors investigate systematic errors introduced in the calibration
of a Stokes polarimeter when the calibration optics deviate from
ideal. To accomplish this, they employ a linearized treatment of the
Mueller calculus which allows for small and arbitrary imperfections
in the Mueller matrices of the calibration optics, as well as a small
amount of polarization in the calibration light source. The authors
find that half of the response matrix elements contain systematic
errors which can be related to imperfections in certain elements of
the Mueller matrices of the calibration optics.
---------------------------------------------------------
Title: Preliminary results from the HAO/NSO Advanced Stokes
Polarimeter prototype observing run.
Authors: Lites, B. W.; Elmore, D.; Murphy, G.; Skumanich, A.; Tomczyk,
S.; Dunn, R. B.
1991sopo.work....3L Altcode:
A prototype version of the Advanced Stokes Polarimeter was operated at
the Sunspot Vacuum Tower Telescope of the National Solar Observatory
in May und June, 1990. Although the prototype instrument does not
have the capability of the final instrument to be deployed in 1991,
it nonetheless provided high spatial resolution Stokes profiles
observations of a small symmetric sunspot. Analysis of these
observations shows that the magnetic field at the outer edge of
the penumbra of this sunspot is highly inclined with respect to the
local normal (γ = 70 - 80°), in agreement with previous Stokes II
measurements of larger sunspots. In addition, the axial field and flux
distribution was found to be nearly identical to that of the previous
Stokes II measurement.
---------------------------------------------------------
Title: Depth and Latitude Dependence of the Solar Internal Angular
Velocity
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain; Tomczyk, Steven; Ulrich, Roger K.; Woodard, Martin F.
1990ApJ...351..687R Altcode:
One of the design goals for the dedicated helioseismology observing
state located at Mount Wilson Observatory was the measurement of the
internal solar rotation using solar p-mode oscillations. In this paper,
the first p-mode splittings obtained from Mount Wilson are reported
and compared with those from several previously published studies. It
is demonstrated that the present splittings agree quite well with
composite frequency splittings obtained from the comparisons. The
splittings suggest that the angular velocity in the solar equatorial
plane is a function of depth below the photosphere. The latitudinal
differential rotation pattern visible at the surface appears to persist
at least throughout the solar convection zone.
---------------------------------------------------------
Title: Solar magnetic fields measurements with a magneto-optical
filter.
Authors: Cacciani, A.; Ricci, D.; Rosati, P.; Rhodes, E. J.; Smith,
E.; Tomczyk, S.; Ulrich, R. K.
1990NCimC..13..125C Altcode:
The presence of a magnetic field at different levels inside the Sun
has crucial implications for helioseismology. The solar oscillation
observing program carried out since 1983 at Mt. Wilson with Cacciani
magneto-optical filter (MOF) has recently been modified to acquire
full-disk magnetograms with 2 arcsec spatial resolution. The authors
present a method for the correct determination of magnetic maps
which are free of contamination by velocity signal. They show that no
cross-talk exists between the Doppler and Zeeman shifts of the Na D
lines, provided that instrumental polarization effects are taken into
account. They also used the observed line-of sight photospheric field
to map the vector field in the inner corona, above active regions,
in the "current free" approximation.
---------------------------------------------------------
Title: An experiment to measure the solar ℓ = 1 rotational
frequency splitting
Authors: Cacciani, A.; Paverani, E.; Ricci, D.; Rosati, P.; Marquedant,
R. M.; Smith, E. J.; Tomczyk, S.
1990LNP...367..197C Altcode: 1990psss.conf..197C
To date, only integrated light experiments have attained the high
signal-to-noise ratio and frequency resolution necessary to measure
the rotational frequency splitting of low degree solar p-modes. These
experiments, however, are limited by the finite mode linewidths coupled
with the inability of non-imaging experiments to unambiguously separate
prograde and retrograde modes. In particular, the separation of the
prograde and retrograde mode frequencies of the very important = 1
spherical harmonic, dictates that the experiment have the capability
to coarsely resolve the eastern from the western hemisphere of the
solar disk. Initial attempts to attain the desired image resolution
by masking the solar image at the focal plane of the telescope and
chopping the two hemispheres on the detector have been unsuccessful
due to the high velocity noise introduced by the solar rotation
through image motions and guiding instabilities. In this paper we
present the concept of what we call spectroscopic masking, which
provides the ability to filter oscillation modes spectroscopically,
and without the need to image the Sun. This results in an optical
configuration which is insensitive to image motions and guiding errors
while still providing adequate spatial resolution to separate prograde
and retrograde = 1 modes. A conceptual study will be presented along
with a test observing run showing the quality of the achievable data.
---------------------------------------------------------
Title: Measurement of the rotational frequency splitting of the solar
five-minute oscillations from magneto-optical filter observations.
Authors: Tomczyk, Steven; Cacciani, Alessandro; Korzennik, Sylvain G.;
Rhodes, Edward J., Jr.; Ulrich, Roger K.
1988ESASP.286..141T Altcode: 1988ssls.rept..141T
Observations of the solar five-minute oscillations in the photospheric
velocity field were obtained during the summer of 1984 at the 60-foot
solar tower of the Mt. Wilson Observatory with a magneto-optical
filter. The magneto-optical filter employs magneto-optical effects in
an atomic vapor to isolate narrow bandpasses in alternate wings of
a spectral line. Time series of full disk velocity images having a
resolution of about 10 arcseconds and a noise level of 15 m/s/pixel
were obtained on 92 days between the months of May and September of
1984. A subset of two time series from this data of 16 and 19 days
duration having a total of 25744 doppler images were analyzed to provide
estimates of the rotational frequency splitting for spherical harmonic
degrees between 5 and 120. The results of this analysis indicate a
decrease in the rate of solar rotation with increasing depth inside
the sun. Also, a decrease in the rate of differential rotation with
increasing depth is observed.
---------------------------------------------------------
Title: Inversion of the solar rotation rate versus depth and latitude.
Authors: Korzennik, Sylvain G.; Cacciani, Alessandro; Rhodes, Edward
J., Jr.; Tomczyk, Steven; Ulrich, Roger K.
1988ESASP.286..117K Altcode: 1988ssls.rept..117K
The authors have used three different inversion techniques to compute
the internal solar rotation rate from several sets of n-averaged
frequency splittings. They have used an iterative variation of the
spectral expansion method, the optimal averaging kernel method and
a piecewise constant constrained least square method to invert the
data. Each computation was carried out independently. While they
present similar trends, each of the solutions differs in detail. A
consistent feature in all the inversions is the disappearance of
differential rotation below the base of the convection zone. Also,
a strong differential signature in the deeper part of the convection
zone is present in most of the solutions. A slow decrease of the
rotation rate with depth for the equatorial and mid-latitude curves
is significant in the spectral expansion and the least square results
but only marginally apparent in the averaging kernel results.
---------------------------------------------------------
Title: Acquisition and reduction procedures for MOF
Doppler-magnetograms.
Authors: Cacciani, Alessandro; Ricci, D.; Rosati, P.; Rhodes, Edward
J., Jr.; Smith, E.; Tomczyk, Steven; Ulrich, Roger K.
1988ESASP.286..185C Altcode: 1988ssls.rept..185C
The authors analyse defects occurred on the MOF first magnetograms,
particularly they discuss the problem of the apparent contamination
between velocity and magnetic fields. They find that a correct
acquisition and reduction procedure gives cleaner results. The authors
also suggest a new vector magnetograph and compute the vector field
at coronal levels using one MOF longitudinal magnetogram.
---------------------------------------------------------
Title: Radial and latitudinal gradients in the solar internal
angular velocity.
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain G.; Tomczyk, Steven; Ulrich, Roger K.; Woodard, Martin F.
1988ESASP.286...73R Altcode: 1988ssls.rept...73R
The authors recently presented the results of an analysis of the
frequency splittings of intermediate-degree (3 < degree ≤ 170)
p-mode oscillations which were obtained from a 16-day subset of our 1984
Mt. Wilson 60-foot tower observations. These results showed evidence
for both radial and latitudinal gradients in the solar internal
angular velocity. In particular, the results indicated that, from
0.6 R<SUB><SUB>sun</SUB></SUB> to 0.95 R<SUB><SUB>sun</SUB></SUB>,
the solar internal angular velocity increases systematically from
440 to 463 nHz, corresponding to a positive radial gradient of ≍66
nHz/R<SUB><SUB>sun</SUB></SUB> for that portion of the solar interior. A
previous analysis indicated that the latitudinal differential rotation
gradient which is seen at the solar surface persists throughout
the convection zone, although there was some indication that the
differential rotation might disappear entirely below the base of the
convection zone. Here the authors extend their previous analysis to
include comparisons with additional observational studies and they
also present comparisons between our earlier results and the results
of additional inversions of several of the observational datasets. All
of these comparisons reinforce the previous conclusions regarding
the existence of radial and latitudinal gradients in the internal
angular velocity.
---------------------------------------------------------
Title: Full-Disk Magnetograms Obtained with a Na Magneto-Optical
Filter at the Mount Wilson Observatory
Authors: Rhodes, E. J.; Cacciani, A.; Garneau, G.; Misch, T.; Progovac,
D.; Shieber, T.; Tomczyk, S.; Ulrich, R. K.
1988BAAS...20..744R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Constancy of Intermediate-Degree p-Mode Frequencies
during the Declining Phase of Solar Cycle 21
Authors: Rhodes, Edward J., Jr.; Woodard, Martin F.; Cacciani,
Alessandro; Tomczyk, Steven; Korzennik, Sylvain G.; Ulrich, Roger K.
1988ApJ...326..479R Altcode:
A comparison of two sets of frequencies of intermediate-degree (6 ≤ l
≤ 89) solar p-mode oscillations obtained in late 1981 and in mid-1984
shows agreement at the level of 0.02 μHz, or better than one part in
10<SUP>5</SUP>. In particular, the frequencies of 573 modes obtained
at the South Pole during 1981 December 24 - 25, (reported by Duvall,
Harvey, and Pomerantz in 1987) were compared with the frequencies of
the same modes as observed at the Mount Wilson Observatory 60 foot
Solar Tower from 1984 July 29 through August 13. It is concluded that
the data are consistent with no change in intermediate-degree p-mode
frequencies between late 1981 and mid-1985.
---------------------------------------------------------
Title: Full-Disk Solar Dopplergrams Observed with a 1024X1024 Pixel
CCD Camera
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
1988IAUS..123..471R Altcode:
The authors present here the first full-disk solar Dopplergram obtained
with the new 1024×1024-pixel CCD camera which has recently been
installed at the 60 foot Tower Telescope of the Mt. Wilson Observatory.
---------------------------------------------------------
Title: Measurements of Solar Internal Rotation Obtained with the
Mt-Wilson 60-FOOT Solar Tower
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Woodard, M.; Tomczyk, S.;
Korzennik, S.; Ulrich, R. K.
1988IAUS..123...41R Altcode:
The authors have obtained estimates of the solar internal rotational
velocity from measurements of the frequency splittings of p-mode
oscillations. Specifically, they have analyzed a 10-day time series
of full-disk Dopplergrams obtained during July and August 1984 at the
60-Foot Tower Telescope of the Mt. Wilson Observatory.
---------------------------------------------------------
Title: A Measurement of the Rotational Frequency Splitting of the
Solar Five-Minute Oscillations.
Authors: Tomczyk, Steven
1988PhDT.........1T Altcode:
Observations of the solar five-minute acoustic oscillations were
employed to probe the sub-surface rotation rate of the sun. The
oscillations were observed in the solar photospheric velocity
field. Full disk velocity images were obtained with a magneto-optical
filter which employs magneto-optical effects in an atomic vapor of
sodium to isolate alternate wings of a spectral line. The observations
were obtained at the 60-foot Solar Tower of the Mt. Wilson Observatory
during the summer of 1984. The time series of velocity images were
analyzed to yield the rotational frequency splitting of oscillation
modes with spherical harmonic degrees ranging from 5 to 120. These
results show the solar rotation rate to decrease with depth inside
the sun over the depth range studied. Also, the rate of differential
rotation is observed to decrease with depth inside the sun.
---------------------------------------------------------
Title: Constancy of Intermediate-degree p-Mode Frequencies During
the Declining Phase of Solar Cycle 21
Authors: Rhodes, E. J., Jr.; Woodard, M. F.; Cacciani, A.; Tomczyk,
S.; Korzennik, S.; Ulrich, R. K.
1987BAAS...19Q.933R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Angular Velocity of the Solar Interior Obtained by an
Asymptotic Inversion of P-Mode Frequency Shifts
Authors: Woodard, M. F.; Rhodes, E. J., Jr.; Tomczyk, S.; Korzennik,
S.; Cacciani, A.; Ulrich, R. K.
1987BAAS...19..934W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Magneto-Optical Filter for Solar Oscillation Measurements
Authors: Tomczyk, S.; Cacciani, A.; Rhodes, E. J., Jr.
1987BAAS...19..701T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Estimates of the solar internal angular velocity obtained
with the Mt. Wilson 60-foot solar tower
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Woodard,
Martin; Tomczyk, Steven; Korzennik, Sylvain; Ulrich, R. K.
1987ASSL..137...75R Altcode: 1987isav.symp...75R
Estimates are obtained of the solar internal angular velocity from
measurements of the frequency splittings of p-mode oscillations. A
16-day time series of full-disk Dopplergrams obtained during July and
August 1984 at the 60-foot tower telescope of the Mt. Wilson Observatory
is analyzed. Power spectra were computed for all of the zonal, tesseral,
and sectoral p-modes from l = 0 to 89 and for all of the sectoral
p-modes from l = 90 to 200. A mean power spectrum was calculated for
each degree up to 89. The frequency differences of all of the different
nonzonal modes were calculated for these mean power spectra.
---------------------------------------------------------
Title: Full-disk solar dopplergrams observed with a one megapixel
CCD camera and sodium magnetooptical filter
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven
1987ASSL..137...69R Altcode: 1987isav.symp...69R
The paper presents here the first two full-disk solar Dopplergrams
obtained with the new 1024 x 1024-pixel CCD camera which has recently
been installed at the 60-Foot Tower Telescope of the Mt. Wilson
Observatory. These Dopplergrams have a spatial resolution of 2.2
arcseconds and were obtained in a total of one minute of time. The
Dopplergrams were obtained with a magnetooptical filter which was
designed to obtain images in the two Na D lines. The filter and the
camera were operated together as part of the development of a solar
oscillations imager experiment which is currently being designed at JPL
for the Joint NASA/ESA Solar and Heliospheric Observatory mission. Two
different images obtained by subtracting two pairs of the Dopplergrams
from the initial time series are also included.
---------------------------------------------------------
Title: Evidence for Radial Gradients in the Solar Internal Rotational
Velocity
Authors: Rhodes, E. J., Jr.; Tomczyk, S.; Woodard, M. F.; Cacciani,
A.; Korzennik, S.; Ulrich, R. K.
1986BAAS...18Q1010R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Applications of the magneto-optical filter to stellar pulsation
measurements
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven
1986ASIC..169..359R Altcode: 1986ssds.proc..359R
A proposed method of employing the Cacciani magneto-optical filter (MOF)
for stellar seismology studies is described. The method relies on the
fact that the separation of the filter bandpasses in the MOF can be
changed by varying the level of input power to the filter cells. With
the use of a simple servosystem the bandpass of a MOF can be tuned to
compensate for the changes in the radial velocity of a star introduced
by the orbital motion of the earth. Such a tuned filter can then be
used to record intensity fluctuations through the MOF bandpass over
an extended period of time for each given star. Also, the use of a two
cell version of the MOF makes it possible to alternately chop between
the bandpass located in the stellar line wing and a second bandpass
located in the stellar continuum. Rapid interchange between the two
channels makes it possible for atmospheric-introduced noise to be
removed from the time series.
---------------------------------------------------------
Title: A one-megapixel image acquisition and processing system for
solar oscillation studies.
Authors: Rhodes, Edward J., Jr.; Bursch, Thomas K.; Ulrich, Roger K.;
Tomczyk, Steven
1986SPIE..627..256R Altcode:
The 1-Mpixel image acquisition and processing system that has been
installed at the Mt. Wilson observatory as part of the development
effort for the NASA/ESA Solar Oscillations Imager Experiment of the
projected Heliospheric Observatory mission is discussed. The system
encompasses a high speed CCD camera with a 1024 x 1024-pixel virtual
phase chip array, yielding a readout rate of about 800,000 pixels/sec;
this allows the entire Mpixel array to be read out in just over 1
sec. The camera is interfaced with a floating point array processor
that integrates several successive exposures from the CCD camera and
differences selected pairs of integrated images. The system is currently
being used to record and difference narrowband images of the sun.
---------------------------------------------------------
Title: The 1984 solar oscillation program of the Mt. Wilson 60-foot
tower.
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk,
Steven; Ulrich, Roger K.
1986ASIC..169..309R Altcode: 1986ssds.proc..309R
The authors describe the instrumentation, data, and preliminary results
from the summer, 1984, solar oscillation observing program which
was carried out using the 60-foot tower telescope of the Mt. Wilson
Observatory.
---------------------------------------------------------
Title: The effects of seeing on noise
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
1985sses.nasa..263U Altcode:
The effect of the supergranulation velocity field combined with seeing
smearing of the solar image on the measurement of solar oscillations
is discussed. Depending on the nature of the observational velocity
determination scheme, the image motions can shift the background
velocity pattern and produce a source of noise that reduces the quality
of the observations. The magnitude of this effect is estimated and
observational results which are consistent with this estimate are
presented.
---------------------------------------------------------
Title: The 1984 solar oscillation program of the Mount Wilson
60-foot tower
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.
1985STIN...8612195R Altcode:
The instrumentation, data, and preliminary results from the summer,
1984, solar oscillation observing program which was carried out
using the 60-foot tower telescope of the Mt. Wilson Observatory
are described. This program was carried out with a dedicated solar
oscillation observing system and obtained full-disk Dopplergrams every
40 seconds for up to 11 hours per day. Between June and September,
1984, observations were obtained with a Na magneto-optical filter on
90 different days. The data analysis has progressed to the point that
spherical harmonic filter functions were employed to generate a few
one-dimensional power spectra from a single day's observations.
---------------------------------------------------------
Title: Evaluation of a magneto-optical filter and a Fabry-Perot
interferometer for the measurement of solar velocity fields from
space.
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Blamont, J.; Tomczyk, S.;
Ulrich, R. K.; Howard, R. F.
1984sses.nasa..125R Altcode: 1984sss..conf..125R
A program was developed to evaluate the performance of three
different devices as possible space-borne solar velocity field
imagers. Two of these three devices, a magneto-optical filter and
a molecular adherence Fabry-Perot interferometer were installed in
a newly-constructed observing system located at the 60-foot tower
telescope at the Mt. Wilson Observatory. Time series of solar
filtergrams and Dopplergrams lasting up to 10 hours per day were
obtained with the filter while shorter runs were obtained with the
Fabry-Perot. Two-dimensional k <SUB>h</SUB>-omega power spectra which
show clearly the well-known p-mode ridges were computed from the time
series obtained with the magneto-optical filter. These power spectra
were compared with similar power spectra obtained recently with the
13.7-m McMath spectrograph at Kitt Peak.
---------------------------------------------------------
Title: Applications of the magneto-optical filter to stellar pulsation
measurements
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
1984STIN...8612187R Altcode:
A proposed method of employing the Cacciani magneto-optical filter (MOF)
for stellar seismology studies is described. The method relies on the
fact that the separation of the filter bandpasses in the MOF can be
changed by varying the level of input power to the filter cells. With
the use of a simple servosystem the bandpass of a MOF can be tuned to
compensate for the changes in the radial velocity of a star introduced
by the orbital motion of the Earth. Such a tuned filter can then be
used to record intensity fluctuations through the MOF bandpass over
an extended period of time for each given star. Also, the use of a two
cell version of the MOF makes it possible to alternately chop between
the bandpass located in the stellar line wing and a second bandpass
located in the stellar continuum. Rapid interchange between the two
channels makes it possible for atmospheric-introduced noise to be
removed from the time series.
---------------------------------------------------------
Title: The effects of seeing on noise.
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
1984sses.nasa..263U Altcode: 1984sss..conf..263U
The authors discuss the effect of the supergranulation velocity field
combined with seeing smearing of the solar image on the measurement
of solar oscillations. Depending on the nature of the observational
velocity determination scheme, the image motions can shift the
background velocity pattern and produce a source of noise that reduces
the quality of the observations. The authors give a rough estimate for
the magnitude of this effect and present observational results which
are consistent with this estimate.
---------------------------------------------------------
Title: Observations of Solar Velocity Fields With Large-Format CCD
Cameras at the Mount Wilson Observatory
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Dumont, P.; Howard, R. F.
1984BAAS...16..979R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Summer 1984 Solar Oscillation Program of the Mount Wilson
60-foot Solar Telescope
Authors: Tomczyk, S.; Rhodes, E. J., Jr.; Cacciani, A.; Ulrich, R. K.;
Howard, R. F.
1984BAAS...16..978T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magneto-Optical Filter Observations of Solar Oscillations at
the Mt. Wilson Observatory
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Dumont, P.; Howard, R. F.
1984BAAS...16..451R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A compact dopplergraph/magnetograph suitable for space-based
measurements of solar oscillations and magnetic fields
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Blamont, J.; Howard, R. F.; Dumont, P.; Smith, E. J.
1984AdSpR...4h.103R Altcode: 1984AdSpR...4..103R
A compact Dopplergraph/magnetograph placed in a continuous solar-viewing
orbit will allow us to make major advancements in our understanding
of solar internal structure and dynamics. An international program
is currently being conducted at JPL and Mt. Wilson to develop such an
instrument. By combining a unique magneto-optical resonance filter with
CID and CCD cameras we have been able to obtain full- and partial-disk
Dopplergrams and magnetograms. Time series of the velocity images are
converted into k-ω power spectra which show clear- the solar nonradial
p-mode oscillations. Magnetograms suitable for studying the long-term
evolution of solar active regions have also been obtained with this
instrument. A flight instrument based on this concept is being studied
for possible inclusion in the SOHO mission.
---------------------------------------------------------
Title: The analysis of solar models: Neutrinos and oscillations
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Tomczyk, S.; Dumont,
P. J.; Brunish, W. M.
1983STIN...8427652U Altcode:
Tests of solar neutrino flux and solar oscillation frequencies
were used to assess standard stellar structure theory. Standard and
non-standard solar models are enumerated and discussed. The field
of solar seismology, wherein the solar interior is studied from the
measurement of solar oscillations, is introduced.
---------------------------------------------------------
Title: Narrow- and intermediate-band Hα and O I λ7774 photometry
andreticon spectroscopy of SX Cassiopeiae.
Authors: Guinan, E. F.; Tomczyk, S.; Turnshek, D. J.
1983PASP...95..364G Altcode:
Observations of the 36.57-day eclipsing binary SX Cas made on eight
nights during February and March 1979 with pairs of intermediate-
and narrow-band filters centered on the wavelengths of the Balmer
H-alpha line and the O I 7774 A triplet are discussed. In addition,
a reticon spectrum covering a wavelength range of 4750 A to 7700
A was obtained in September 1979, showing strong H-beta and H-alpha
emission lines as well as absorption features of the K-giant component
of the system. From the photometry, strong H-alpha emission is found
at all the orbital phases sampled. However, no appreciable O I 7774
A line emission is detected. It is noted that the strong H-alpha
emission is consistent with the presence of significant amounts of
circumstellar and circumbinary gas. From the observations, it appears
that the H-alpha emitting region is centered chiefly on the primary
component, but the gas is partially eclipsed by the larger cool giant
during primary eclipse. The H-alpha-emitting region therefore appears
larger than the dimensions of the stellar components. In addition,
the apparent nonrepeatability of the H-alpha emission strength from
one orbital cycle to the next implies that relatively rapid changes
in the extent or quantity of gas occur in the system.
---------------------------------------------------------
Title: Evidence for starspots on the DK Draconis (HR 4665).
Authors: Guinan, E. F.; McCook, G. P.; Fragola, J. L.; Odonnell,
W. C.; Tomczyk, S.; Weisenberger, A. G.
1982AJ.....87..893G Altcode:
Observations of the long-period RS CVn-type binary DK Dra from
February through September 1978 are presented. Light variations
appear to be quasisinusoidal with a period of 64.6 + or - 0.4 d, and
cycle-to-cycle changes in the character of the light curve have most
likely occurred. No evidence of H-alpha or O I emission is found. A
starspot model is used to generate theoretical light curves which fit
those observed. Results indicate that the minimum spotted area is about
8% of the stellar surface area, which suggests that the fractional
spotted area is at least 40-80 times greater for DK Dra than the
total fractional area on the sun at sunspot maximum. An analysis of
multibandpass data shows that the temperature difference between the
photosphere and spot is about 1100 K.
---------------------------------------------------------
Title: The Sensitivity of Eigenfrequencies of Intermediate L Solar
Oscillations to Solar Structure
Authors: Ulrich, R. K.; Tomczyk, S.; Rhodes, E. J., Jr.
1982pccv.conf..138U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The analysis of solar models - neutrinos and oscillations.
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Tomczyk, S.; Dumont,
P. J.; Brunish, W. M.
1982AIPC...96...66U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Period Variability of SX Cassiopeiae
Authors: Guinan, E. F.; Tomczyk, S.
1979IBVS.1623....1G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hydrogen shell flashes in massive accreting white dwarfs.
Authors: Sion, E. M.; Acierno, M. J.; Tomczyk, S.
1979ApJ...230..832S Altcode:
In the present paper, the long-term evolution of massive accreting
white dwarfs in close binary systems is discussed in context of several
astrophysical problems. It is shown that high surface luminosity models
with spherically symmetric accretion (rather than disk accretion) yield
very short interflash periods for massive white dwarfs accreting at
high rates. The shell flashes exhibited by the models are not strong
enough to eject mass, as in classical novae. However, the repetitive
hydrogen shell flashes with an interflash period of 17 years may
be relevant to understanding the underlying variability of the blue
component of symbiotic variables if the blue component is a white dwarf.
---------------------------------------------------------
Title: Nova Cygni 1978
Authors: Guinan, E. F.; McCook, G. P.; Tomczyk, S.; de Young, J.;
Morgan, J.; Mattei, M.; Wallentinsen, D.; Hawley, W.; Collins, P. L.;
Peltier, L. C.; Hurless, C.
1978IAUC.3274....1G Altcode:
E. F. Guinan, G. P. McCook and S. Tomczyk, Department of Astronomy,
Villanova University, write: "Photoelectric wide- and narrow-band
6565 and 7774 A observations of Nova Cyg 1978 were made at Villanova
University Observatory on Sept. 15.04-15.12 and 16.03-16.16
UT. Observations indicate variations in the wide-bandpasses of ~
0.08 magnitude over the first night and of less than ~ 0.03 magnitude
on the second night. The apparent brightnesses were about the same on
both nights. An increase in net emission at H-alpha and at O I (7774 A)
was also observed between the two nights." Corrigendum. On IAUC 3270,
line 19, for strong structure at 3920 A read strong structure at 3820
A. Visual magnitude estimates: Sept. 19.03 UT, 7.6 (J. De Young,
Huntington, WV); 19.16, 7.7 (J. Morgan, Prescott, AZ); 20.16, 7.7
(M. Mattei, Littleton, MA); 20.39, 7.6 (D. Wallentinsen, Albuquerque,
NM); 21.11, 8.2 (W. Hawley, Concord, NH); 22.35, 8.0 (P. L. Collins,
Mount Hopkins Observatory); 23.03, 8.2 (L. C. Peltier, Delphos, OH);
24.02, 8.3 (C. Hurless, Lima, OH).
---------------------------------------------------------
Title: Hα Photometry of X Persei
Authors: Guinan, E. F.; McCook, G. P.; Acierno, M.; del Conte, R.;
Lupie, O.; Tomczyk, S.; Young, K.; Dorren, J. D.; Siah, M. J.
1978BAAS...10..632G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evolutionary Models of Accreting Massive White Dwarfs.
Authors: Sion, E. M.; Acierno, M.; Tomczyk, S.
1977BAAS....9R.634S Altcode:
No abstract at ADS
