explanation      blue bibcodes open ADS page with paths to full text
Author name code: judge
ADS astronomy entries on 2022-09-14
author:"Judge, Philip G."

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Title: Thermal and Non-thermal Properties of Active Region Recurrent
    Coronal Jets
Authors: Paraschiv, Alin R.; Donea, Alina C.; Judge, Philip G.
2022ApJ...935..172P    Altcode: 2022arXiv220712612P
  We present observations of recurrent active region coronal jets,
  and derive their thermal and non-thermal properties, by studying
  the physical properties of the plasma simultaneously at the base
  footpoint and along the outflow of jets. The sample of analyzed solar
  jets were observed by SDO-AIA in extreme ultraviolet and by RHESSI
  in the X-ray domain. The main thermal plasma physical parameters,
  such as temperature, density, energy flux contributions, etc.,
  are calculated using multiple inversion techniques to obtain the
  differential emission measure from extreme-ultraviolet filtergrams. The
  underlying models are assessed, and their limitations and applicability
  are scrutinized. Complementarily, we perform source reconstruction
  and spectral analysis of higher energy X-ray observations to further
  assess the thermal structure and identify non-thermal plasma emission
  properties. We discuss a peculiar penumbral magnetic reconnection
  site, which we previously identified as a "Coronal Geyser." Evidence
  supporting cool and hot thermal emission, as well as non-thermal
  emission, is presented for a subset of geyser jets. These active
  region jets are found to be energetically stronger than their polar
  counterparts, but we find their potential influence on heliospheric
  energetics and dynamics to be limited. We scrutinize whether the
  geyser does fit the non-thermal erupting microflare picture, finding
  that our observations at peak flaring times can only be explained by a
  combination of thermal and non-thermal emission models. This analysis
  of geysers provides new information and observational constraints
  applicable to theoretical modeling of solar jets.

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Title: A Spectroscopic Survey of Infrared 1-4 μm Spectra in Regions
    of Prominent Solar Coronal Emission Lines of Fe XIII, Si X, and Si IX
Authors: Ali, Aatiya; Paraschiv, Alin Razvan; Reardon, Kevin; Judge,
   Philip
2022ApJ...932...22A    Altcode: 2022arXiv220308636A
  The infrared solar spectrum contains a wealth of physical data about
  the Sun and is being explored using modern detectors and technology
  with new ground-based solar telescopes. One such instrument will be
  the ground-based Cryogenic Near-IR Spectro-Polarimeter of the Daniel
  K. Inouye Solar Telescope (DKIST), which will be capable of sensitive
  imaging of the faint infrared solar coronal spectra with full Stokes I,
  Q, U, and V polarization states. Highly ionized magnetic dipole emission
  lines have been observed in galaxies and the solar corona. Quantifying
  the accuracy of spectral inversion procedures requires a precise
  spectroscopic calibration of observations. A careful interpretation
  of the spectra around prominent magnetic dipole lines is essential
  for deriving physical parameters and particularly for quantifying the
  off-limb solar coronal observations from DKIST. In this work, we aim to
  provide an analysis of the spectral regions around the infrared coronal
  emission lines of Fe XIII 1074.68 nm, Fe XIII 1079.79 nm, Si X 1430.10
  nm, and Si IX 3934.34 nm, aligning with the goal of identifying solar
  photospheric and telluric lines that will help facilitate production of
  reliable inversions and data products from four sets of solar coronal
  observations. The outputs can be integrated in processing pipelines
  to produce level 2 science-ready data.

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Title: The mercurial Sun at the heart of our solar system
Authors: Judge, Philip Gordon
2022arXiv220503498J    Altcode:
  As the powerhouse of our solar system, the Sun's electromagnetic
  planetary influences appear contradictory. On the one hand, the Sun
  for aeons emitted radiation which was "just right" for life to evolve
  in our terrestrial Goldilocks zone, even for such complex organisms
  as ourselves. On the other, in the dawn of Earth's existence the Sun
  was far dimmer than today, and yet evidence for early liquid water is
  written into geology. Now in middle age, the Sun should be a benign
  object of little interest to society or even astronomers. However,
  for physical reasons yet to be fully understood, it contains a magnetic
  machine with a slightly arrhythmic 11 year magnetic heartbeat. Although
  these variations require merely 0.1% of the solar luminosity, this power
  floods the solar system with rapidly changing fluxes of photons and
  particles at energies far above the 0.5eV thermal energy characteristic
  of the photosphere. Ejected solar plasma carries magnetic fields into
  space with consequences for planets, the Earth being vulnerable to
  geomagnetic storms. This chapter discusses some physical reasons why
  the Sun suffers from such ailments, and examine consequences through
  time across the solar system. A Leitmotiv of the discussion is that
  any rotating and convecting star must inevitably generate magnetic
  "activity" for which the Sun represents the example par excellence.

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Title: Efficient and Automated Inversions of Magnetically Sensitive
Forbidden Coronal Lines: CLEDB - The Coronal Line Emission DataBase
    Magnetic Field Inversion Algorithm
Authors: Paraschiv, Alin Razvan; Judge, Philip Gordon
2022SoPh..297...63P    Altcode: 2022arXiv220414111P
  We present CLEDB, a "single-point inversion" algorithm for inferring
  parameters using I , Q , U , and V Stokes parameters of forbidden
  magnetic dipole lines formed in the solar corona. We select lines
  of interest and construct databases of Stokes parameters for
  combinations of plasma thermal and magnetic configurations. The
  size and complexity of such databases are drastically reduced by
  taking advantage of symmetries. Using wavelength-integrated line
  profiles, each of which might be decomposed beforehand into several
  line-of-sight components, we search for nearest matches to observed
  Stokes parameters computed for the elongation corresponding to the
  observed region. The method is intended to be applied to two or
  more lines observed simultaneously. The solutions initially yield
  magnetic orientation, thermal properties, and the spatial position of
  the emitting plasma in three dimensions. Multiple possible solutions
  for each observation are returned, including irreducible degeneracies,
  where usually sets of two solutions are compatible with the two input I
  , Q , U , and V measurements. In solving for the scattering geometry,
  this method avoids an additional degeneracy pointed out by Dima and
  Schad (Astrophys. J.889, 109, 2020). The magnetic field strength
  is separately derived from the simple ratio of observed to database
  Stokes V data, after the thermal properties and scattering geometry
  solutions have been determined.

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Title: Study the tortoise, not just the hare
Authors: Judge, P.
2022fysr.confE..50J    Altcode:
  Darwin encountered enormous Galapagos tortoises in 1835 around the
  time that Schwabe was collecting sunspot numbers. The creatures were
  slow and easy to study. Of course, fauna from the Galapagos played a
  central role in our understanding of evolution of life; genetic records
  imprinted in modern animals have since given us pages in the book of
  life history. Skumanich's 1972 work represents the first 3 pages in the
  book of stellar magnetic evolution, studying (like Darwin) only what was
  observable at a given time. The Sun and stars continue to be studied by
  politically palatable 1-10 year long missions, measuring short duration
  phenomena -- analogous to the peculiar springtime "boxing" of the March
  Hare. Stellar activity measurements over multiple decades (sampling
  sun-like cycling) are now a part of history, just as their need from
  space weather, dynamo theory, exoplanet habitability seems greater
  than ever. The communities must support tortoise-like measurements
  of stellar chromospheric signatures, extending the record begun in
  1965, and used by Andy in 1972. A "palatable path" might be through
  development of automated observatories at under-privileged colleges,
  I present some ideas along these lines.

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Title: How to Measure the Magnetic Origins of Coronal Dynamics
Authors: Gilbert, Holly; Judge, Philip
2021AGUFMSH12C..03G    Altcode:
  To identify the origins of coronal dynamics, we have examined
  how we might measure magnetic free energy and topology and their
  evolution above the solar surface. Given the challenges associated
  with extrapolations based upon magnetic field measurements in the
  photosphere, we identify a region in the near UV part of the spectrum
  as optimal for studying the development of magnetic free energy over
  active regions. We demonstrate that the challenges are best met through
  a combination of near UV lines of bright Mg II, and lines of Fe II and
  Fe I mostly within the 4s-4p transition array. The lines form across
  the entire chromosphere and into the lower transition region. Based
  upon the recently-reported successful suborbital space measurements
  of magnetic fields with the CLASP2 instrument, we argue that a modest
  space-borne telescope will be able to make significant advances in
  the attempts to predict solar eruptions.

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Title: CLEDB - An Algorithm for Inverting Vector Magnetic Fields in
    The Solar Corona
Authors: Paraschiv, Alin; Judge, Philip
2021AGUFMSH42B..06P    Altcode:
  We present an algorithm capable of inverting coronal vector magnetic
  field information from observations of polarized light. The CLEDB
  algorithm implements two branches that can process full Stokes IQUV
  spectro-polarimetric observations of one or two coronal emission
  lines.The 1-line branch uses analytical approximations to derive
  line of sight integrated magnetic field products. When posing an
  inversion problem, the second branch allows for more degrees of freedom
  enabling us to break intrinsic degeneracies. Thus, by utilizing 2-line
  Stokes observations, we recover the 3D magnetic fields and volumetric
  locations of emitting structures for single-point voxels. In practice,
  forward calculation in the order of 107-109 atomic plasma, magnetic,
  and geometric configurations are needed in order to satisfy solution
  resolution criteria.Forward modelling this many solutions in an
  iterative fashion is dreadfully time consuming, rendering such approach
  as unfeasible. We bypassed the limitation by building databases, that
  store vast sets of synthetic Stokes IQUV signals, via forward modelling
  of parameter combinations. Using a 2 fitting approach has proved to
  be significantly more robust in matching such databases with Stokes
  IQUV observations.Additionally, the database theoretical calculations
  gain intrinsic access to otherwise non-observable input parameters,
  e.g. atomic alignment, that can be used to break inherent degeneracies
  encountered when attempting analytical inversions like in the 1-line
  case. The dimensionality of the problem at hand can be further reduced
  by 1-2 orders of magnitude by using native symmetries when building
  and querying databases. The goal of robustly resolving vector coronal
  magnetometry has been hard to achieve. The need for inverting magnetic
  fields from solar spectro-polarimetric observations is crucial, as the
  next generation of coronal capable instruments like DKIST Cryo-NIRSP,
  DL-NIRSP, and UCOMP will become operational. Benchmarks of the CLEDB
  algorithm tested against synthetic data are explored, while we wait
  for the first ever full Stokes spectro-polarimetric observations to
  become available.

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Title: From 1973 to the 2020s, from SKYLAB to 3D vector magnetic
    fields in prominences
Authors: Lacatus, Daniela; Judge, Philip; Gilbert, Holly; Paraschiv,
   Alin; Berger, Thomas
2021AGUFMSH42B..05L    Altcode:
  Routine measurement of the vector magnetic fields threading prominences
  would mark a significant advance in our ability to determine the
  dynamics of the Sun's corona. Gilbert et al. (AGU abstract #849653)
  have identified the near-UV (250-281 nm) as a prime region for
  measurements of magnetic fields within the chromosphere and lower
  transition region. Here, we perform an in depth analysis of the near
  UV spectra of all prominences observed by the SKYLAB SO82B instrument
  during 1973, for the first time. Using over 100 spectral lines we
  process the photographic data from scratch, and solve for plasma
  properties of several prominences. Given the known complexity of the
  thermal and dynamical conditions within prominence plasma, we develop
  a model to find mean electron temperatures, densities and mass columns
  which capture each spectrums essential characteristics. Prominence
  plasmas are optically thick in the cores of many spectral lines of Fe
  II and Mg II present in this spectral region. The different optical
  depths probe different surfaces along the line-of-sight, so that
  near-UV spectro-polarimetry will uniquely determine vector magnetic
  fields within the 3D volume of prominences. Therefore, we show that
  this technique offers the best future method for answering critical
  problems related to coronal dynamics, not only above active regions
  as shown by Gilbert et al., but also in prominence plasmas.

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Title: Atomic Structure Calculations of Landé g Factors of
    Astrophysical Interest with Direct Applications for Solar Coronal
    Magnetometry
Authors: Schiffmann, Sacha; Brage, Tomas; Judge, Philip Gordon;
   Paraschiv, Alin Razvan; Wang, Kai
2021ApJ...923..186S    Altcode:
  We perform a detailed theoretical study of the atomic structure of
  ions with ns <SUP>2</SUP> np <SUP> m </SUP> ground configurations
  and focus on departures from LS coupling, which directly affect the
  Landé g factors of magnetic dipole lines between levels of the ground
  terms. Particular emphasis is given to astrophysically abundant ions
  formed in the solar corona (those with n = 2,3) with M1 transitions
  spanning a broad range of wavelengths. Accurate Landé g factors are
  needed to diagnose coronal magnetic fields using measurements from
  new instruments operating at visible and infrared wavelengths, such
  as the Daniel K. Inouye Solar Telescope. We emphasize an explanation
  of the dynamics of atomic structure effects for nonspecialists.

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Title: The enduring mystery of the solar corona
Authors: Judge, Philip G.
2021PhyW...34...38J    Altcode:
  Physicists have long known that the Sun's magnetic fields make its
  corona much hotter than the surface of the star itself. But how -
  and why - those fields transport and deposit their energy is still a
  mystery, as Philip G Judge explains.

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Title: Erratum: Spectral Lines for Polarization Measurements of the
    Coronal Magnetic Field. II. Consistent Treatment of the Stokes Vector
    for Magnetic-dipole Transitions (1999, ApJ, 522, 524)
Authors: Casini, R.; Judge, P. G.
2021ApJ...917...50C    Altcode:
  No abstract at ADS

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Title: Measuring the Magnetic Origins of Solar Flares, Coronal Mass
    Ejections, and Space Weather
Authors: Judge, Philip; Rempel, Matthias; Ezzeddine, Rana; Kleint,
   Lucia; Egeland, Ricky; Berdyugina, Svetlana V.; Berger, Thomas; Bryans,
   Paul; Burkepile, Joan; Centeno, Rebecca; de Toma, Giuliana; Dikpati,
   Mausumi; Fan, Yuhong; Gilbert, Holly; Lacatus, Daniela A.
2021ApJ...917...27J    Altcode: 2021arXiv210607786J
  We take a broad look at the problem of identifying the magnetic
  solar causes of space weather. With the lackluster performance
  of extrapolations based upon magnetic field measurements in the
  photosphere, we identify a region in the near-UV (NUV) part of the
  spectrum as optimal for studying the development of magnetic free energy
  over active regions. Using data from SORCE, the Hubble Space Telescope,
  and SKYLAB, along with 1D computations of the NUV spectrum and numerical
  experiments based on the MURaM radiation-magnetohydrodynamic and
  HanleRT radiative transfer codes, we address multiple challenges. These
  challenges are best met through a combination of NUV lines of bright Mg
  II, and lines of Fe II and Fe I (mostly within the 4s-4p transition
  array) which form in the chromosphere up to 2 × 10<SUP>4</SUP>
  K. Both Hanle and Zeeman effects can in principle be used to derive
  vector magnetic fields. However, for any given spectral line the τ
  = 1 surfaces are generally geometrically corrugated owing to fine
  structure such as fibrils and spicules. By using multiple spectral
  lines spanning different optical depths, magnetic fields across nearly
  horizontal surfaces can be inferred in regions of low plasma β, from
  which free energies, magnetic topology, and other quantities can be
  derived. Based upon the recently reported successful sub-orbital space
  measurements of magnetic fields with the CLASP2 instrument, we argue
  that a modest space-borne telescope will be able to make significant
  advances in the attempts to predict solar eruptions. Difficulties
  associated with blended lines are shown to be minor in an Appendix.

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Title: Magnetic Connections across the Chromosphere-Corona Transition
    Region
Authors: Judge, Philip
2021ApJ...914...70J    Altcode: 2021arXiv210407753J
  The plasma contributing to emission from the Sun between the cool
  chromosphere (≤10<SUP>4</SUP> K) and hot corona (≥10<SUP>6</SUP> K)
  has been subjected to many different interpretations. Here we look at
  the magnetic structure of this transition region (TR) plasma, based
  upon the implications of CLASP2 data of an active region recently
  published by Ishikawa et al., and earlier Interface Region Imaging
  Spectrograph (IRIS) and Solar Dynamics Observatory (SDO) data of quiet
  regions. Ishikawa et al. found that large areas of sunspot plages
  are magnetically unipolar as measured in the cores of Mg II resonance
  lines, formed in the lower TR under low plasma-β conditions. Here we
  show that IRIS images in the line cores have fibrils that are well
  aligned with the overlying coronal loop segments seen in the 171 Å
  channel of SDO. When the TR emission in active regions arises from
  plasma magnetically and thermally connected to the corona, then the
  line cores can provide the first credible magnetic boundary conditions
  for force-free calculations extended to the corona. We also re-examine
  IRIS images of dynamic TR cool loops previously reported as a major
  contributor to TR emission from the quiet Sun. Dynamic cool loops
  contribute only a small fraction of the total TR emission from the
  quiet Sun.

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Title: On Single-point Inversions of Magnetic Dipole Lines in
    the Corona
Authors: Judge, Philip; Casini, Roberto; Paraschiv, Alin Razvan
2021ApJ...912...18J    Altcode: 2021arXiv210303824J
  Prompted by a recent paper by Dima and Schad, we reconsider the problem
  of inferring magnetic properties of the corona using polarimetric
  observations of magnetic dipole (M1) lines. Dima and Schad point to a
  potential source of degeneracy in a formalism developed by Plowman,
  which under some circumstances can lead to the solution being
  under-determined. Here we clarify the nature of the problem. Its
  resolution lies in solving for the scattering geometry using the
  elongation of the observed region of the corona. We discuss some
  conceptual problems that arise when casting the problem for inversion in
  the observer's reference frame, and satisfactorily resolve difficulties
  identified by Plowman, Dima, and Schad.

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Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
    (DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
   Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
   Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
   Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
   Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
   Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
   Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
   Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
   Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
   Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
   Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
   Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
   Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
   Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
   Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
   Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
   Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
   E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
   Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
   Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
   Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
   Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
   A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
   Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
   Instrument Scientists; DKIST Science Working Group; DKIST Critical
   Science Plan Community
2021SoPh..296...70R    Altcode: 2020arXiv200808203R
  The National Science Foundation's Daniel K. Inouye Solar Telescope
  (DKIST) will revolutionize our ability to measure, understand,
  and model the basic physical processes that control the structure
  and dynamics of the Sun and its atmosphere. The first-light DKIST
  images, released publicly on 29 January 2020, only hint at the
  extraordinary capabilities that will accompany full commissioning of
  the five facility instruments. With this Critical Science Plan (CSP)
  we attempt to anticipate some of what those capabilities will enable,
  providing a snapshot of some of the scientific pursuits that the DKIST
  hopes to engage as start-of-operations nears. The work builds on the
  combined contributions of the DKIST Science Working Group (SWG) and
  CSP Community members, who generously shared their experiences, plans,
  knowledge, and dreams. Discussion is primarily focused on those issues
  to which DKIST will uniquely contribute.

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Title: Spectroscopic Inversions &amp; Calibrations for DKIST Coronal
    Observations
Authors: Ali, A.; Paraschiv, A.; Reardon, K.; Judge, P. G.
2020AGUFMSH0280014A    Altcode:
  The Cryo-NIRSP's (Cryogenic Near-IR Spectro-Polarimeter) is one of the
  DKIST instruments capable of sensitive imaging of faint infrared coronal
  solar spectra, and its primary goal is to measure the full polarization
  state (Stokes I, Q, U and V) of spectral lines originating on the Sun
  at different wavelengths. Producing data products from off-limb solar
  coronal observations from the DKIST telescope is essential when trying
  to study its future observations. Quantifying the accuracy of spectral
  inversion procedures based on its spectral comparisons to absorption
  and telluric calibrated spectra will give insight to interpreting
  valid DKIST observations and its ultimate findings. Using simulated
  contaminated data of both pure and noisy data sets has allowed us
  to compare the wavelength shifts and broadening properties to help
  pinpoint where contamination would affect the data set as a whole,
  and by how much. In doing so, we developed code that will eventually
  be integrated in the DKIST Level-2 pipeline. Working to compare
  these findings to absorption and telluric readings will further help
  minimize the uncertainties read in through observations, and give
  direction on how to reduce the original coronal data in hopes to refine
  it. Understanding the origins and magnitude of the contamination would
  therefore help refine the original coronal data and make it compatible
  for data processing, and would assist the automation of processing
  the data observed by the DKIST telescope.

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Title: Spectropolarimetric Insight into Plasma Sheet Dynamics of a
    Solar Flare
Authors: French, R.; Judge, P. G.; Matthews, S.; van Driel-Gesztelyi,
   L.; Long, D.
2020AGUFMSH045..03F    Altcode:
  Magnetic reconnection is thought to lie at the heart of energy release
  in solar flares, but the process is not yet fully understood. We examine
  spectropolarimetric data from the CoMP coronagraph, acquired a few hours
  into the evolution of the September 10th 2017 X8.2-class flare. We
  find a striking and spatially coherent low polarisation structure,
  aligned with the hot plasma sheet observed in EUV. By elimination,
  we find the significant depolarisation to be a result of small-scale
  sub-pixel magnetic structure along the plasma sheet, consistent with
  theory of reconnection instabilities. This interpretation of ongoing
  reconnection is supported by further Hinode/EIS observations and AIA
  DEMs, from well beyond the impulsive phase of the flare. The plasma
  sheet remains visible in CoMP linear polarisation over a day into the
  flare's evolution, several hours after its last appearance in EUV. We
  conclude that polarisation measurements with new coronagraphs, such
  the DKIST CRYO-NIRSP instrument, will further enhance our understanding
  of magnetic reconnection during eruptive flares.

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Title: Automated Single Point Inversions of Infrared Forbidden Lines
    for DKIST Coronal Observations
Authors: Paraschiv, A.; Judge, P. G.; Ali, A.
2020AGUFMSH0280013P    Altcode:
  We present preliminary results on an inversion scheme that can be
  applied to polarimetric measurements of forbidden lines formed in
  the solar corona. <P />We aim to find optimal fits to synthetic CLE
  data, delivering information on the vector magnetic field, thermal
  properties and line of sight position from a single point in the
  corona. We calculate the azimuthal angle from the linear polarization
  and estimate the line-of-sight magnetic fields via the magnetograph
  formulation. Our method complements these calculations to achieve vector
  magnetic fields. We create a database of emergent Stokes profiles from a
  Monte Carlo exploration of the parameter space. In building the database
  set, we first reduce the line formation problem to an irreducible form,
  factoring out linear parameters such as the magnetic field strength,
  and using native symmetries in the line formation problem to reduce
  the dimensionality of the needed calculations. We "precondition" the
  observed data with simple linear transformations and a rotation of
  the Stokes profiles around the line-of-sight axis through Sun center,
  which affects only the linearly polarized components. We show that
  calculations confined to the ecliptic plane are sufficient to explore
  the full 3D space. After the best-fit profiles are found, the necessary
  transformations are applied in reverse to the matching geometric,
  magnetic and thermal parameters to estimate them in 3D space. We then
  highlight the natural degeneracies in the analysis and examine their
  accuracy and sensitivity to noise.

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Title: Inevitable consequences of ion-neutral damping of intermediate
    MHD waves in Sun-like stars
Authors: Judge, Philip G.
2020MNRAS.498.2018J    Altcode: 2020MNRAS.tmp.2062J; 2020arXiv200803607J
  In the context of the solar atmosphere, we re-examine the role
  of neutral and ionized species in dissipating the ordered energy
  of intermediate-mode MHD waves into heat. We solve conservation
  equations for the hydrodynamics and for hydrogen and helium ionization
  stages, along closed tubes of magnetic field. First, we examine the
  evolution of coronal plasma under conditions where coronal heating has
  abruptly ceased. We find that cool (&lt;10<SUP>5</SUP>K) structures
  are formed lasting for several hours. MHD waves of modest amplitude
  can heat the plasma through ion-neutral collisions with sufficient
  energy rates to support the plasma against gravity. Then we examine
  a calculation starting from a cooler atmosphere. The calculation
  shows that warm (&gt;10<SUP>4</SUP>) K long (&gt; several Mm) tubes
  of plasma arise by the same mechanism. We speculate on the relevance
  of these solutions to observe properties of the Sun and similar stars
  whose atmospheres are permeated with emerging magnetic fields and
  stirred by convection. Perhaps this elementary process might help to
  explain the presence of 'cool loops' in the solar transition region
  and the production of broad components of transition region lines. The
  production of ionized hydrogen from such a simple and perhaps inevitable
  mechanism may be an important step towards finding the more complex
  mechanisms needed to generate coronae with temperatures in excess of
  10<SUP>6</SUP>K, independent of a star's metallicity.

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Title: Dynamics of Late-stage Reconnection in the 2017 September 10
    Solar Flare
Authors: French, Ryan J.; Matthews, Sarah A.; van Driel-Gesztelyi,
   Lidia; Long, David M.; Judge, Philip G.
2020ApJ...900..192F    Altcode: 2020arXiv200713377F
  In this multi-instrument paper, we search for evidence of sustained
  magnetic reconnection far beyond the impulsive phase of the X8.2-class
  solar flare on 2017 September 10. Using Hinode/EIS, CoMP, SDO/AIA,
  K-Cor, Hinode/XRT, RHESSI, and IRIS, we study the late-stage evolution
  of the flare dynamics and topology, comparing signatures of reconnection
  with those expected from the standard solar flare model. Examining
  previously unpublished EIS data, we present the evolution of nonthermal
  velocity and temperature within the famous plasma sheet structure,
  for the first four hours of the flare's duration. On even longer
  timescales, we use differential emission measures and polarization data
  to study the longevity of the flare's plasma sheet and cusp structure,
  discovering that the plasma sheet is still visible in observations
  of CoMP linear polarization on 2017 September 11, long after its last
  appearance in EUV. We deduce that magnetic reconnection of some form
  is still ongoing at this time—27 hr after flare onset.

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Title: New Light on an Old Problem of the Cores of Solar Resonance
    Lines
Authors: Judge, Philip G.; Kleint, Lucia; Leenaarts, Jorrit;
   Sukhorukov, Andrii V.; Vial, Jean-Claude
2020ApJ...901...32J    Altcode: 2020arXiv200801250J
  We reexamine a 50+ yr old problem of deep central reversals predicted
  for strong solar spectral lines, in contrast to the smaller reversals
  seen in observations. We examine data and calculations for the resonance
  lines of H I, Mg II, and Ca II, the self-reversed cores of which form
  in the upper chromosphere. Based on 3D simulations, as well as data for
  the Mg II lines from the Interface Region Imaging Spectrograph (IRIS),
  we argue that the resolution lies not in velocity fields on scales in
  either of the micro- or macroturbulent limits. Macroturbulence is ruled
  out using observations of optically thin lines formed in the upper
  chromosphere, and by showing that it would need to have unreasonably
  special properties to account for critical observations of the Mg
  II resonance lines from the IRIS mission. The power in "turbulence"
  in the upper chromosphere may therefore be substantially lower than
  earlier analyses have inferred. Instead, in 3D calculations horizontal
  radiative transfer produces smoother source functions, smoothing out
  intensity gradients in wavelength and in space. These effects increase
  in stronger lines. Our work will have consequences for understanding
  the onset of the transition region, for understanding the energy in
  motions available for heating the corona, and for the interpretation
  of polarization data in terms of the Hanle effect applied to resonance
  line profiles.

---------------------------------------------------------
Title: Automated Single Point Inversions of Infrared Forbidden Lines
    for DKIST Coronal Observations
Authors: Paraschiv, A.; Judge, P.
2020SPD....5120302P    Altcode:
  We present preliminary results on an inversion scheme that can
  be applied to polarimetric measurements of forbidden lines formed
  in the solar corona. We aim to find optimal fits to synthetic CLE
  data, delivering information on the vector magnetic field, thermal
  properties and line of sight position from a single point in the
  corona. The azimuthal angle is derived from the linear polarization
  and the line-of-sight magnetic fields are derived via the magnetograph
  formulation. Our method complements these calculations to achieve full
  vector magnetic fields. We create a database of emergent Stokes profiles
  from a Monte Carlo exploration of the parameter space. In building
  the database set, we first reduce the line formation problem to an
  irreducible form, factoring out linear parameters such as the magnetic
  field strength, and using native symmetries in the line formation
  problem to reduce the dimensionality of the needed calculations. We
  "precondition" the observed data with simple linear transformations and
  a rotation of the Stokes profiles around the line-of-sight axis through
  Sun center, which affects only the linearly polarized components. We
  show that calculations confined to the ecliptic plane are sufficient
  to explore the full 3D space. After the best-fit profiles are found,
  the necessary transformations are applied in reverse to the matching
  geometric, magnetic and thermal parameters to estimate them in 3D
  space. We then highlight the natural degeneracies in the analysis and
  examine their accuracy and sensitivity to noise.

---------------------------------------------------------
Title: Spectropolarimetric Insight into Plasma Sheet Dynamics of a
    Solar Flare
Authors: French, R.; Judge, P.; Matthews, S.; van Driel-Gesztelyi,
   L.; Long, D.
2020SPD....5121102F    Altcode:
  Magnetic reconnection is thought to lie at the heart of energy release
  in solar flares, but the process is not yet fully understood. We examine
  spectropolarimetric data from the CoMP coronagraph, acquired a few hours
  into the evolution of the September 10th 2017 X8.2-class flare. We
  find a striking and spatially coherent low polarisation structure,
  aligned with the hot plasma sheet observed in EUV. By elimination,
  we find the significant depolarisation to be a result of small-scale
  sub-pixel magnetic structure along the plasma sheet, consistent with
  theory of reconnection instabilities. This interpretation of ongoing
  reconnection is supported by further Hinode/EIS observations and AIA
  DEMs, from well beyond the impulsive phase of the flare. The plasma
  sheet remains visible in CoMP linear polarisation over a day into the
  flare's evolution, several hours after its last appearance in EUV. We
  conclude that polarisation measurements with new coronagraphs, such
  the DKIST CRYO-NIRSP instrument, will further enhance our understanding
  of magnetic reconnection during eruptive flares.

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

---------------------------------------------------------
Title: The Sun: A Very Short Introduction
Authors: Judge, Philip Gordon
2020svsi.book.....J    Altcode:
  The Sun, as our nearest star, is of enormous importance for life
  on Earth - providing the warm radiation and light which allowed
  complex life to evolve. The Sun plays a key role in influencing our
  climate, whilst solar storms and high-energy events can threaten
  our communication infrastructure and satellites. <P />This Very
  Short Introduction explores what we know about the Sun, its physics,
  its structure, origins, and future evolution. Philip Judge explains
  some of the remaining puzzles about the Sun that still confound us,
  using elementary physics, and mathematical concepts. Why does the Sun
  form spots? Why does it flare? As he shows, these and other nagging
  difficulties relate to the Sun's continually variable magnetism,
  which converts an otherwise dull star into a machine for flooding
  interplanetary space with variable radiation, high-energy particles
  and magnetic ejections. Throughout, Judge highlights the many reasons
  that the Sun is important, and why scientists engage in solar research.

---------------------------------------------------------
Title: Sun-like Stars Shed Light on Solar Climate Forcing
Authors: Judge, P. G.; Egeland, R.; Henry, G. W.
2020ApJ...891...96J    Altcode: 2020arXiv200204633J
  Recently published precise stellar photometry of 72 Sun-like stars
  obtained at the Fairborn Observatory between 1993 and 2017 is used
  to set limits on the solar forcing of Earth's atmosphere of ±4.5
  W m<SUP>-2</SUP> since 1750. This compares with the +2.2 ± 1.1 W
  m<SUP>-2</SUP> IPCC estimate for anthropogenic forcing. Three critical
  assumptions are made. In decreasing order of importance they are:
  (a) most of the brightness variations occur within the average time
  series length of ≈17 yr; (b) the Sun seen from the ecliptic behaves
  as an ensemble of middle-aged solar-like stars; and (c) narrowband
  photometry in the Strömgren b and y bands are linearly proportional
  to the total solar irradiance. Assumption (a) can best be relaxed and
  tested by obtaining more photometric data of Sun-like stars, especially
  those already observed. Eight stars with near-solar parameters have
  been observed from 1999, and two since 1993. Our work reveals the
  importance of continuing and expanding ground-based photometry, to
  complement expensive solar irradiance measurements from space.

---------------------------------------------------------
Title: Some thoughts on emission-line spectroscopy
Authors: Judge, Philip G.
2020MNRAS.491..576J    Altcode: 2019MNRAS.tmp.2640J
  The interpretation of emission lines formed in large astrophysical
  plasmas such as the solar atmosphere faces many challenges. Relatively
  simple line-ratio estimates of physical parameters, while appealing,
  are heavily laden with assumptions. In practical cases, some critical
  assumptions are neither defensible from first principles, nor testable
  by experiment. Free parameters and functional forms must be defined,
  whose numbers of degrees of freedom exceed the number of independent
  data points. These issues are illustrated in the particular case of
  using lines of Si IV and O IV formed in the solar transition region,
  observed for decades, most recently using the IRIS mission. The problems
  highlighted are in addition to well-known problems of mathematical
  ill-posedness.

---------------------------------------------------------
Title: Spectropolarimetric Insight into Plasma Sheet Dynamics of a
    Solar Flare
Authors: French, Ryan J.; Judge, Philip G.; Matthews, Sarah A.;
   van Driel-Gesztelyi, Lidia
2019ApJ...887L..34F    Altcode: 2019arXiv191112666F
  We examine spectropolarimetric data from the Coronal Multi-channel
  Polarimeter (CoMP) instrument, acquired during the evolution of the 2017
  September 10 X8.2 solar flare on the western solar limb. CoMP captured
  linearly polarized light from two emission lines of Fe XIII at 1074.7
  and 1079.8 nm, from 1.03 to 1.5 solar radii. We focus here on the hot
  plasma sheet lying above the bright flare loops and beneath the ejected
  coronal mass ejection. The polarization has a striking and coherent
  spatial structure, with unexpectedly small polarization aligned with
  the plasma sheet. By elimination, we find that small-scale magnetic
  field structure is needed to cause such significant depolarization,
  and suggest that plasmoid formation during reconnection (associated
  with the tearing-mode instability) creates magnetic structure on scales
  below instrument resolution of 6 Mm. We conclude that polarization
  measurements with new coronagraphs, such as the upcoming Daniel
  K. Inouye Solar Telescope, will further enhance our understanding of
  magnetic reconnection and development of turbulence in the solar corona.

---------------------------------------------------------
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.

---------------------------------------------------------
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).

---------------------------------------------------------
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: Multiwavelength High-resolution Observations of Chromospheric
    Swirls in the Quiet Sun
Authors: Shetye, Juie; Verwichte, Erwin; Stangalini, Marco; Judge,
   Philip G.; Doyle, J. G.; Arber, Tony; Scullion, Eamon; Wedemeyer, Sven
2019ApJ...881...83S    Altcode:
  We report observations of small-scale swirls seen in the solar
  chromosphere. They are typically 2 Mm in diameter and last around
  10 minutes. Using spectropolarimetric observations obtained by the
  CRisp Imaging Spectro-Polarimeter at the Swedish 1 m Solar Telescope,
  we identify and study a set of swirls in chromospheric Ca II 8542 Å
  and Hα lines as well as in the photospheric Fe I line. We have three
  main areas of focus. First, we compare the appearance, morphology,
  dynamics, and associated plasma parameters between the Ca II and Hα
  channels. Rotation and expansion of the chromospheric swirl pattern
  are explored using polar plots. Second, we explore the connection to
  underlying photospheric magnetic concentration (MC) dynamics. MCs are
  tracked using the SWAMIS tracking code. The swirl center and MC remain
  cospatial and share similar periods of rotation. Third, we elucidate
  the role swirls play in modifying chromospheric acoustic oscillations
  and found a temporary reduction in wave period during swirls. We use
  cross-correlation wavelets to examine the change in period and phase
  relations between different wavelengths. The physical picture that
  emerges is that a swirl is a flux tube that extends above an MC in a
  downdraft region in an intergranular lane. The rotational motion of
  the MC matches the chromospheric signatures. We could not determine
  whether a swirl is a gradual response to the photospheric motion or
  an actual propagating Alfvénic wave.

---------------------------------------------------------
Title: HAOS-DIPER: HAO Spectral Diagnostic Package For Emitted
    Radiation
Authors: Judge, P. G.
2019ascl.soft05009J    Altcode:
  HAOS-DIPER works with and manipulates data for neutral atoms and
  atomic ions to understand radiation emitted by some space plasmas,
  notably the solar atmosphere and stellar atmospheres. HAOS-DIPER
  works with quantum numbers for atomic levels, enabling it to perform
  tasks otherwise difficult or very tedious, including a variety of data
  checks, calculations based upon the atomic numbers, and searching and
  manipulating data based upon these quantum numbers. HAOS-DIPER handles
  conditions from LTE to coronal-like conditions, in a manner controlled
  by one system variable !REGIME, and has some capability for estimating
  data for which no accurate parameters are available and for accounting
  for the effects of missing atomic levels.

---------------------------------------------------------
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: Erratum: “Discovery of New Coronal Lines at 2.843 and 2.853
μm” (<A href="http://doi.org/10.3847/2041-8213/aab434">2018,
    ApJL, 856, L29</A>)
Authors: Samra, Jenna E.; Judge, Philip G.; DeLuca, Edward E.;
   Hannigan, James W.
2019ApJ...873L..25S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Measuring solar surface magnetic fields without ambiguity
Authors: Judge, Philip G.
2019MNRAS.482.5542J    Altcode: 2018MNRAS.tmp.2891J
  The goal of this paper is to find a method to yield solar surface
  magnetic field measurements while inflicting minimal prior assumptions
  on the acceptable solutions. A small spacecraft placed at least 0.1
  radian away from the Earth-Sun line can, with vector field observations
  from the Earth, offer unambiguous determinations of magnetic fields
  from the Sun. A telescope of between 10 and 40 cm aperture operating at
  ultraviolet (UV) wavelengths can, with a simple Stokes-V polarimeter,
  enhance observations made with the suite of large telescopes on the
  Earth. A 40 cm aperture can achieve the same diffraction limit at
  400 nm that Daniel K. Innouye Solar Telescope (DKIST) might achieve
  at 4 microns. Even a 10 cm aperture offers higher signal to noise in
  Stokes V than DKIST can Q and U in magnetic fields outside sunspots,
  transverse to the line of sight, offering enormous benefits for
  understanding magnetic components transverse to the Earth-Sun line. We
  identify UV and infrared (IR) lines of Fe I that are useful for joint
  spacecraft-DKIST observations. Benefits of space observations also
  include line-of-sight fields measured in strong chromospheric lines
  in the UV that are free of seeing, such as Ca II H&amp;K and Mg II
  h&amp;k. A simple mission devoted to such space measurements will
  enhance our understanding of solar magnetism and hence, space weather
  and space climate, for decades to come.

---------------------------------------------------------
Title: VizieR Online Data Catalog: UV spectrum of molecular hydrogen
    in the Sun (Jaeggli+, 2018)
Authors: Jaeggli, S. A.; Judge, P. G.; Daw, A. N.
2019yCat..18550134J    Altcode:
  Ultraviolet (UV) lines of molecular hydrogen have been observed in
  solar spectra for almost four decades, but the behavior of the molecular
  spectrum and its implications for solar atmospheric structure are not
  fully understood. Data from the High-Resolution Telescope Spectrometer
  (HRTS) instrument revealed that H2 emission forms in particular regions,
  selectively excited by a bright UV transition region and chromospheric
  lines. We test the conditions under which H2 emission can originate
  by studying non-LTE models, sampling a broad range of temperature
  stratifications and radiation conditions. Stratification plays the
  dominant role in determining the population densities of H2, which
  forms in greatest abundance near the continuum photosphere. However,
  opacity due to the photoionization of Si and other neutrals determines
  the depth to which UV radiation can penetrate to excite the H2. Thus
  the majority of H2 emission forms in a narrow region, at about 650km
  in standard one-dimensional (1D) models of the quiet Sun, near the
  {tau}=1 opacity surface for the exciting UV radiation, generally coming
  from above. When irradiated from above using observed intensities of
  bright UV emission lines, detailed non-LTE calculations show that the
  spectrum of H2 seen in the quiet-Sun Solar Ultraviolet Measurement of
  Emitted Radiation atlas spectrum and HRTS light-bridge spectrum can
  be satisfactorily reproduced in 1D stratified atmospheres, without
  including three-dimensional or time-dependent thermal structures. A
  detailed comparison to observations from 1205 to 1550Å is presented,
  and the success of this 1D approach to modeling solar UV H2 emission
  is illustrated by the identification of previously unidentified lines
  and upper levels in HRTS spectra. <P />(3 data files).

---------------------------------------------------------
Title: Chapter 5 - Spectroscopy and Atomic Physics
Authors: Judge, Philip G.
2019sgsp.book..127J    Altcode: 2019sgsp.book..127.
  A short guide to spectroscopy is given with an emphasis on the
  elementary physics needed to understand and begin modeling the radiation
  emerging from astrophysical plasmas using the Sun as a guide, without
  bias toward a particular region of the Sun's atmosphere. The Sun is the
  astronomical body par excellence upon which our tools for exploring
  the universe have been most carefully developed. Observable solar
  plasmas span a broad range of conditions and consequently extremes
  of local thermodynamic equilibrium deep in the atmosphere, to extreme
  non-local thermodynamical equilibrium conditions in the corona and wind,
  including nonstatistical equilibrium conditions. For brevity, important
  subjects are omitted, notably non-Maxwellian electron distributions,
  line broadening, polarization, particle diffusion, and high-energy and
  collective phenomena of importance, at radio and hard x-ray wavelengths.

---------------------------------------------------------
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: Solar UV Molecular Hydrogen Fluorescence
Authors: Daw, Adrian Nigel; Jaeggli, Sarah Amelia; Judge, Philip G.;
   Roueff, Evelyne; Abgrall, Hervé
2018tess.conf21706D    Altcode:
  Solar observations of ultraviolet molecular hydrogen lines indicate
  that H<SUB>2</SUB> emission forms in particular regions, selectively
  excited by bright UV transition region and chromospheric lines. IRIS
  frequently observes numerous H<SUB>2</SUB> lines during flares and
  smaller energetic events, but the diagnostic value of these lines for
  probing the structure of the solar atmosphere has heretofore remained
  largely unexploited. We present a synthesis method for H<SUB>2</SUB>
  emission, using 1-D non-LTE models sampling a broad range of temperature
  stratifications and input radiation conditions from the atmosphere
  above, and compare the results to observations by IRIS, SUMER and
  HRTS from 1205 to 1550 Å. Because opacity due to photoionization of
  silicon and other neutrals determines the depth to which UV radiation
  can penetrate to excite the H<SUB>2</SUB>, the majority of H<SUB>2</SUB>
  emission forms in a narrow region near the tau=1 opacity surface for
  the exciting UV radiation, generally coming from above. The success
  of this 1-D approach to modeling solar UV H<SUB>2</SUB> emission is
  illustrated by the identification of previously unidentified lines and
  upper levels. Applications of the observed emission and implications
  for solar atmospheric structure are discussed.

---------------------------------------------------------
Title: Discovery of New Coronal Lines at 2.843 and 2.853 μm
Authors: Samra, Jenna E.; Judge, Philip G.; DeLuca, Edward E.;
   Hannigan, James W.
2018ApJ...856L..29S    Altcode:
  Two new emission features were observed during the 2017 August 21
  total solar eclipse by a novel spectrometer, the Airborne Infrared
  Spectrometer (AIR-Spec), flown at 14.3 km altitude aboard the NCAR
  Gulfstream-V aircraft. We derive wavelengths in air of 2.8427 ±
  0.00009 μm and 2.8529 ± 0.00008 μm. One of these lines belongs to the
  3{{{p}}}<SUP>5</SUP>3{{d}}{}<SUP>3</SUP>{{{F}}}<SUB>3</SUB><SUP>^\circ
  </SUP>\to
  3{{{p}}}<SUP>5</SUP>3{{d}}{}<SUP>3</SUP>{{{F}}}<SUB>4</SUB><SUP>^\circ
  </SUP> transition in Ar-like Fe IX. This appears to be the first
  detection of this transition from any source. Minimization of
  residual wavelength differences using both measured wavelengths,
  together with National Institute of Standards and Technology (NIST)
  extreme ultraviolet wavelengths, does not clearly favor assignment to
  Fe IX. However, the shorter wavelength line appears more consistent
  with other observed features formed at similar temperatures to Fe
  IX. The transition occurs between two levels within the excited
  3{{{p}}}<SUP>5</SUP>3{{d}} configuration, 429,000 cm<SUP>-1</SUP>
  above the ground level. The line is therefore absent in photo-ionized
  coronal-line astrophysical sources such as the Circinus Galaxy. Data
  from a Fourier transform interferometer (FTIR) deployed from Wyoming
  show that both lines are significantly attenuated by telluric
  H<SUB>2</SUB>O, even at dry sites. We have been unable to identify
  the longer wavelength transition.

---------------------------------------------------------
Title: Formation of the UV Spectrum of Molecular Hydrogen in the Sun
Authors: Jaeggli, S. A.; Judge, P. G.; Daw, A. N.
2018ApJ...855..134J    Altcode: 2018arXiv180203779J
  Ultraviolet (UV) lines of molecular hydrogen have been observed in
  solar spectra for almost four decades, but the behavior of the molecular
  spectrum and its implications for solar atmospheric structure are not
  fully understood. Data from the High-Resolution Telescope Spectrometer
  (HRTS) instrument revealed that H<SUB>2</SUB> emission forms in
  particular regions, selectively excited by a bright UV transition
  region and chromospheric lines. We test the conditions under which
  H<SUB>2</SUB> emission can originate by studying non-LTE models,
  sampling a broad range of temperature stratifications and radiation
  conditions. Stratification plays the dominant role in determining
  the population densities of H<SUB>2</SUB>, which forms in greatest
  abundance near the continuum photosphere. However, opacity due to
  the photoionization of Si and other neutrals determines the depth to
  which UV radiation can penetrate to excite the H<SUB>2</SUB>. Thus
  the majority of H<SUB>2</SUB> emission forms in a narrow region,
  at about 650 km in standard one-dimensional (1D) models of the quiet
  Sun, near the τ = 1 opacity surface for the exciting UV radiation,
  generally coming from above. When irradiated from above using observed
  intensities of bright UV emission lines, detailed non-LTE calculations
  show that the spectrum of H<SUB>2</SUB> seen in the quiet-Sun Solar
  Ultraviolet Measurement of Emitted Radiation atlas spectrum and HRTS
  light-bridge spectrum can be satisfactorily reproduced in 1D stratified
  atmospheres, without including three-dimensional or time-dependent
  thermal structures. A detailed comparison to observations from 1205 to
  1550 Å is presented, and the success of this 1D approach to modeling
  solar UV H<SUB>2</SUB> emission is illustrated by the identification
  of previously unidentified lines and upper levels in HRTS spectra.

---------------------------------------------------------
Title: Magnetic Diagnostics of the Solar Corona: Synthesizing Optical
    and Radio Techniques
Authors: Casini, R.; White, S. M.; Judge, P. G.
2018smf..book..145C    Altcode:
  No abstract at ADS

---------------------------------------------------------
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: Formation of the UV Spectrum of Molecular Hydrogen in the Sun
Authors: Jaeggli, S. A.; Judge, P. G.; Daw, A. N.
2017AGUFMSH52B..01J    Altcode:
  UV lines of molecular hydrogen in the Sun have been observed for almost
  four decades, but the behavior of the spectra and their implications
  for solar atmospheric structure are not fully understood. Data from the
  HRTS instrument revealed that H2 emission forms in particular regions,
  selectively excited by bright UV transition region and chromospheric
  lines. We test the conditions under which H2 emission can originate
  by studying non-LTE models with increasingly complex temperature
  stratification. Stratification plays the dominant role in determining
  the population densities of H2, which can form in abundance only within
  about 700 km of the continuum photosphere where 3D and dynamic structure
  generally play secondary roles to stratification. When irradiated
  from above using observed intensities of bright UV emission lines,
  detailed non-LTE calculations show that the spectrum of H2 can be
  satisfactorily modeled in 1D stratified atmospheric models, with no
  need to invoke unusual 3D or time dependent thermal structures.

---------------------------------------------------------
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: Surveying the IR corona during the 2017 solar eclipse
Authors: Bryans, P.; Hannigan, J. W.; Sewell, S. D.; Judge, P. G.
2017AGUFMSH13B2479B    Altcode:
  The spectral emission of the infrared solar corona is the most
  promising direct diagnostic of the coronal magnetic field, and
  yet remains poorly measured. During the 2017 total solar eclipse,
  we will perform the first spectral survey of the IR corona using
  the NCAR Airborne Interferometer. This Fourier Transform Infrared
  Spectrometer is configured to observe the coronal spectrum from 1.5
  to 5.5 microns at R 10,000 from a ground-based site. The location
  is atop Casper Mountain, Wyoming (42.73ºN, 106.32ºW, 2400 masl),
  8 km from the center-line of totality. In this presentation, we will
  outline the need for such measurements, describe the instrument design
  and adaptation for the eclipse measurement, observation scheme, and
  present preliminary results. We will also discuss implications for
  observing infrared coronal lines from the ground, for example with
  the upcoming DKIST facility.

---------------------------------------------------------
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: Efficient Radiative Transfer for Dynamically Evolving
    Stratified Atmospheres
Authors: Judge, Philip G.
2017ApJ...851....5J    Altcode:
  We present a fast multi-level and multi-atom non-local thermodynamic
  equilibrium radiative transfer method for dynamically evolving
  stratified atmospheres, such as the solar atmosphere. The
  preconditioning method of Rybicki &amp; Hummer (RH92) is adopted. But,
  pressed for the need of speed and stability, a “second-order
  escape probability” scheme is implemented within the framework
  of the RH92 method, in which frequency- and angle-integrals are
  carried out analytically. While minimizing the computational work
  needed, this comes at the expense of numerical accuracy. The iteration
  scheme is local, the formal solutions for the intensities are the only
  non-local component. At present the methods have been coded for vertical
  transport, applicable to atmospheres that are highly stratified. The
  probabilistic method seems adequately fast, stable, and sufficiently
  accurate for exploring dynamical interactions between the evolving MHD
  atmosphere and radiation using current computer hardware. Current 2D
  and 3D dynamics codes do not include this interaction as consistently
  as the current method does. The solutions generated may ultimately
  serve as initial conditions for dynamical calculations including full
  3D radiative transfer. <P />The National Center for Atmospheric Research
  is sponsored by the National Science Foundation.

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

---------------------------------------------------------
Title: The Magnetic Future of the Sun
Authors: Judge, Philip G.; Egeland, Ricky; Metcalfe, Travis S.;
   Guinan, Edward; Engle, Scott
2017ApJ...848...43J    Altcode: 2017arXiv171005088J
  We analyze space- and ground-based data for the old (7.0 ± 0.3
  Gyr) solar analogs 16 Cyg A and B. The stars were observed with the
  Cosmic Origins UV Spectrographs on the Hubble Space Telescope (HST)
  on 2015 October 23 and 2016 February 3, respectively, and with the
  Chandra X-ray Observatory on 2016 February 7. Time-series data in
  Ca II data are used to place the UV data in context. The UV spectra
  of 18 Sco (3.7 ± 0.5 Gyr), the Sun (4.6 ± 0.04 Gyr), and α Cen A
  ({5.4}<SUB>-0.2</SUB><SUP>+1.2</SUP> {Gyr}) appear remarkably similar,
  pointing to a convergence of magnetic heating rates for G2 main-sequence
  stars older than ≈2-4 Gyr. But the B component’s X-ray (0.3-2.5
  keV) flux lies 20× below a well-known minimum level reported by
  Schmitt. As reported for α Cen A, the coronal temperature probably
  lies below that detectable in soft X-rays. No solar UV flux spectra
  of comparable resolution to those of stellar data exist, but they are
  badly needed for comparison with stellar data. Center-to-limb variations
  are reevaluated for lines such as Ca II through X-rays, with important
  consequences for observing activity cycles in such features. We also
  call into question work that has mixed solar intensity-intensity
  statistics with flux-flux relations of stars.

---------------------------------------------------------
Title: Solar Spectral Lines with Special Polarization Properties
    for the Calibration of Instrument Polarization
Authors: Li, W.; Casini, R.; del Pino Alemán, T.; Judge, P. G.
2017ApJ...848...82L    Altcode:
  We investigate atomic transitions that have previously been identified
  as having zero polarization from the Zeeman effect. Our goal is
  to identify spectral lines that can be used for the calibration of
  instrumental polarization of large astronomical and solar telescopes,
  such as the Daniel K. Inouye Solar Telescope, which is currently
  under construction on Haleakala. We use a numerical model that
  takes into account the generation of scattering polarization and
  its modification by the presence of a magnetic field of arbitrary
  strength. We adopt values for the Landé factors from spectroscopic
  measurements or semi-empirical results, thus relaxing the common
  assumption of LS-coupling previously used in the literature. The
  mechanisms dominating the polarization of particular transitions are
  identified, and we summarize groups of various spectral lines useful
  for the calibration of spectropolarimetric instruments, classified
  according to their polarization properties.

---------------------------------------------------------
Title: Atomic physics and solar polarimetry
Authors: Judge, P. G.
2017CaJPh..95..847J    Altcode: 2017arXiv170707090J
  Observational solar physics is entering a new era with the advent of
  new 1.5 m class telescopes with adaptive optics, as well as the Daniel
  K. Inouye 4 m telescope which will become operational in 2019. Major
  outstanding problems in solar physics all relate to the solar magnetic
  field. Spectropolarimetry offers the best, and sometimes only, method
  for accurate measurements of the magnetic field. In this paper we
  highlight how certain atomic transitions can help us provide both
  calibration data, as well as diagnostic information on solar magnetic
  fields, in the presence of residual image distortions through the
  atmosphere close to, but not at the diffraction limits of large and
  polarizing telescopes. Particularly useful are spectral lines of
  neutrals and singly charged ions of iron and other complex atoms. As
  a proof-of-concept, we explore atomic transitions that might be used
  to study magnetic fields without the need for an explicit calibration
  sequence, offering practical solutions to the difficult challenges
  of calibrating the next generation of solar spectropolarimetric
  telescopes. Suggestions for additional work on atomic theory and
  measurements, particularly at infrared wavelengths, are given. There
  is some promise for continued symbiotic advances between solar physics
  and atomic physics.

---------------------------------------------------------
Title: A Novel Strategy to Seek Biosignatures at Enceladus and Europa
Authors: Judge, Philip
2017AsBio..17..852J    Altcode: 2017arXiv170707230J
  A laboratory experiment is suggested in which conditions similar
  to those in the plume ejecta from Enceladus and, perhaps, Europa are
  established. Using infrared spectroscopy and polarimetry, the experiment
  might identify possible bio-markers in differential measurements of
  water from the open-ocean, from hydrothermal vents, and abiotic water
  samples. Should the experiment succeed, large telescopes could be
  used to acquire sensitive infrared spectra of the plumes of Enceladus
  and Europa, as the satellites transit the bright planetary disks. The
  extreme technical challenges encountered in so doing are similar to
  those of solar imaging spectropolarimetry. The desired signals are
  buried in noisy data in the presence of seeing-induced image motion
  and a changing natural source. Some differential measurements used
  for solar spectropolarimetry can achieve S/N ratios of $10^5$ even in
  the presence of systematic errors two orders of magnitude larger. We
  review the techniques and likelihood of success of such an observing
  campaign with some of the world's largest ground-based telescopes, as
  well as the long anticipated James Webb Space Telescope. We discuss
  the relative merits of the new 4m Daniel K. Inouye Solar Telescope,
  as well as the James Webb Space Telescope and larger ground-based
  observatories, for observing the satellites of giant planets. As seen
  from near Earth, transits of Europa occur regularly, but transits of
  Enceladus will begin again only in 2022.

---------------------------------------------------------
Title: Magnetic Diagnostics of the Solar Corona: Synthesizing Optical
    and Radio Techniques
Authors: Casini, R.; White, S. M.; Judge, P. G.
2017SSRv..210..145C    Altcode: 2017SSRv..tmp...91C
  In this contribution we review the current state-of-the-art of
  coronal magnetometry, in both optical and radio domains. We address
  the achievable objectives and the challenges of present measurement
  techniques and interpretation tools. In particular, we focus on the
  role that these observations can play for constraining and validating
  numerical models of the global coronal magnetic field. With regard
  to optical techniques, we mainly focus on the use of M1 diagnostics,
  further developing the theory of the formation of their polarization
  signatures in the magnetized corona.

---------------------------------------------------------
Title: On the Fine Structure Splitting of the 3p43d 4D5/2 and 3p43d
    4D7/2 Levels of Fe X
Authors: Judge, Philip; Hutton, Roger; Li, Wenxian; Brage, Tomas
2017arXiv170707077J    Altcode:
  We study UV spectra obtained with the SO82-B slit spectrograph on
  board SKYLAB to estimate the fine structure splitting of the Cl-like
  3p4 3d 4D J=5/2 and 3p4 3d 4D J=7/2 levels of Fe X. The splitting is
  of interest because the Zeeman effect mixes these levels, producing a
  "magnetically induced transition" (MIT) from 3p4 3d 4D J=7/2 to 3p5 2Po
  J=3/2 for modest magnetic field strengths characteristic of the active
  solar corona. We estimate the splitting using the Ritz combination
  formula applied to two lines in the UV region of the spectrum close
  to 1603.2 Angstrom, which decay from the level 3p4(1D)3d 2G J=7/2
  to these two lower levels. The MIT and accompanying spin-forbidden
  transition lie near 257 Angstrom. By careful inspection of a deep
  exposure obtained with the S082B instrument we derive a splitting of
  &lt;~ 7 +/- 3 cm-1. The upper limit arises because of a degeneracy
  between the effects of non-thermal line broadening and fine-structure
  splitting for small values of the latter parameter. Although the data
  were recorded on photographic film, we solved for optimal values of
  line width and splitting of 8.3 +/- 0.9 and 3.6 +/- 2.7 cm-1.

---------------------------------------------------------
Title: An Explanation of Remarkable Emission-line Profiles in
    Post-flare Coronal Rain
Authors: Lacatus, Daniela A.; Judge, Philip G.; Donea, Alina
2017ApJ...842...15L    Altcode: 2017arXiv170707069L
  We study broad redshifted emission in chromospheric and transition
  region lines that appears to correspond to a form of post-flare
  coronal rain. Profiles of Mg II, C II, and Si IV lines were obtained
  using IRIS before, during, and after the X2.1 flare of 2015 March 11
  (SOL2015-03-11T16:22). We analyze the profiles of the five transitions
  of Mg II (the 3p-3s h and k transitions, and three lines belonging to
  the 3d-3p transitions). We use analytical methods to understand the
  unusual profiles, together with higher-resolution observational data
  of similar phenomena observed by Jing et al. The peculiar line ratios
  indicate anisotropic emission from the strands that have cross-strand
  line center optical depths (k line) of between 1 and 10. The lines
  are broadened by unresolved Alfvénic motions whose energy exceeds
  the radiation losses in the Mg II lines by an order of magnitude. The
  decay of the line widths is accompanied by a decay in the brightness,
  suggesting a causal connection. If the plasma is ≲99% ionized,
  ion-neutral collisions can account for the dissipation; otherwise, a
  dynamical process seems necessary. Our work implies that the motions are
  initiated during the impulsive phase, to be dissipated as radiation over
  a period of an hour, predominantly by strong chromospheric lines. The
  coronal “rain” we observe is far more turbulent than most earlier
  reports have indicated, with implications for plasma heating mechanisms.

---------------------------------------------------------
Title: Are All Flare Ribbons Simply Connected to the Corona?
Authors: Judge, Philip G.; Paraschiv, Alin; Lacatus, Daniela; Donea,
   Alina; Lindsey, Charlie
2017ApJ...838..138J    Altcode: 2017arXiv170707072J
  We consider the observational basis for the belief that flare
  ribbons in the chromosphere result from energy transport from the
  overlying corona. We study ribbons of small flares using magnetic
  and intensity data from the Hinode, Solar Dynamics Observatory, and
  IRIS missions. While most ribbons appear connected to the corona and
  overlie regions of significant vertical magnetic field, we examine
  one ribbon with no clear evidence for such connections. Evolving
  horizontal magnetic fields seen with Hinode suggest that reconnection
  with preexisting fields below the corona can explain the data. The
  identification of just one, albeit small, ribbon, with no apparent
  connection to the corona, leads us to conclude that at least two
  mechanisms are responsible for the heating that leads to flare ribbon
  emission. <P />The National Center for Atmospheric Research is sponsored
  by the National Science Foundation.

---------------------------------------------------------
Title: Vector Magnetic Field Measurements along a Cooled Stereo-imaged
    Coronal Loop
Authors: Schad, T. A.; Penn, M. J.; Lin, H.; Judge, P. G.
2016ApJ...833....5S    Altcode: 2016arXiv161005332S
  The variation of the vector magnetic field along structures in
  the solar corona remains unmeasured. Using a unique combination of
  spectropolarimetry and stereoscopy, we infer and compare the vector
  magnetic field structure and three-dimensional morphology of an
  individuated coronal loop structure undergoing a thermal instability. We
  analyze spectropolarimetric data of the He I λ10830 triplet
  (1s2s{}<SUP>3</SUP>{S}<SUB>1</SUB>-1s2p{}<SUP>3</SUP>{P}<SUB>{2,1,0</SUB>})
  obtained at the Dunn Solar Telescope with the Facility Infrared
  Spectropolarimeter on 2011 September 19. Cool coronal loops are
  identified by their prominent drainage signatures in the He I data
  (redshifts up to 185 km s<SUP>-1</SUP>). Extinction of EUV background
  radiation along these loops is observed by both the Atmospheric Imaging
  Assembly on board the Solar Dynamics Observatory and the Extreme
  Ultraviolet Imager on board spacecraft A of the Solar Terrestrial
  Relations Observatory, and is used to stereoscopically triangulate
  the loop geometry up to heights of 70 Mm (0.1R <SUB>Sun</SUB>) above
  the solar surface. The He I polarized spectra along this loop exhibit
  signatures indicative of atomic-level polarization, as well as magnetic
  signatures through the Hanle and Zeeman effects. Spectropolarimetric
  inversions indicate that the magnetic field is generally oriented
  along the coronal loop axis, and provide the height dependence of the
  magnetic field intensity. The technique we demonstrate is a powerful
  one that may help better understand the thermodynamics of coronal
  fine-structure magnetism.

---------------------------------------------------------
Title: Estimates Of Magnetic Plage Filling Factors Using The Cn Band
Authors: Saar, Steven H.; Judge, Philip
2016csss.confE.151S    Altcode:
  The 388nm CN band (like the better known "G band" of CH) is used in the
  Sun to locate strong magnetic concentrations. Magnetic network and plage
  are bright in these molecular bands, since the enhanced chromospheric
  heating there destroys the molecule, erasing its absorption and allowing
  the continuum to shine through. We take advantage of this to estimate
  the filling factor of strong fields in active dwarf stars. CN band
  depths in active stars can be compared with those of inactive stars of
  very similar temperature and metallicity, and after an adjustment for
  line-blanketing, used to estimate a magnetic plage filling factor. We
  estimate filling factors for a two stars, and compare them to direct
  Stokes I line-broadening measurements. Limitations, caveats, and future
  directions are briefly considered.

---------------------------------------------------------
Title: On the Fine Structure Splitting of the 3p<SUP>4</SUP>3d
    <SUP>4</SUP>D<SUB>5/2</SUB> and 3p<SUP>4</SUP>3d
    <SUP>4</SUP>D<SUB>7/2</SUB> Levels of Fe X
Authors: Judge, Philip G.; Hutton, Roger; Li, Wenxian; Brage, Tomas
2016ApJ...833..185J    Altcode:
  We study UV spectra obtained with the SO82-B slit spectrograph on board
  SKYLAB to estimate the fine structure (FS) splitting of the Cl-like
  3{{{p}}}<SUP>4</SUP>3{{d}}{}<SUP>4</SUP>{{{D}}}<SUB>5/2</SUB> and
  3{{{p}}}<SUP>4</SUP>3{{d}}{}<SUP>4</SUP>{{{D}}}<SUB>7/2</SUB> levels
  of Fe x. The splitting is of interest because the Zeeman effect mixes
  these levels, producing a “magnetically induced transition” (MIT)
  from 3{{{p}}}<SUP>4</SUP>3{{d}}{}<SUP>4</SUP>{{{D}}}<SUB>7/2</SUB> to
  3{{{p}}}<SUP>5</SUP>{}<SUP>2</SUP>{{{P}}}<SUB>3/2</SUB><SUP>{{o</SUP>}}
  for modest magnetic field strengths characteristic of the
  active solar corona. We estimate the splitting using the Ritz
  combination formula applied to two lines in the UV region
  of the spectrum close to 1603.2 Å, which decay from the level
  3{{{p}}}<SUP>4</SUP>{(}<SUP>1</SUP>{{D}})3{{d}}{}<SUP>2</SUP>{{{G}}}<SUB>7/2</SUB>
  to these two lower levels. The MIT and accompanying spin-forbidden
  transition lie near 257 Å. By careful inspection of a deep exposure
  obtained with the S082B instrument, we derive a splitting of ≲ 7+/-
  3 cm<SUP>-1</SUP>. The upper limit arises because of a degeneracy
  between the effects of non-thermal line broadening and FS splitting for
  small values of the latter parameter. Although the data were recorded
  on photographic film, we solved for optimal values of line width and
  splitting of 8.3 ± 0.9 and 3.6 ± 2.7 cm<SUP>-1</SUP>.

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

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

---------------------------------------------------------
Title: The March 11, 2015 X2.1 flare: peculiar post-flare spectral
    signatures
Authors: Lacatus, Daniela Adriana; Donea, A.; Judge, P. G.
2016shin.confE.207L    Altcode:
  The only X-class flare of 2015 observed by IRIS occurred at 16:22
  UT on 11 March 2015, in AR 12297. This flare generated significant
  seismic transients in the photosphere at the eastern location of the
  flare. IRIS observations of the chromosphere and transition region
  help us understand the physics of the sunquake. In this work we will
  analyze this event using data from IRIS, SDO, and RHESSI. Unfortunately,
  the IRIS rasters scanned the area between the main footpoints of the
  solar flare. Whereas, the main X-ray emission dominates the eastern
  footprint. Significant enhancements in the chromospheric and TR lines
  intensities were measured. The forbidden line of Fe XXI 1354.1 Å
  is detected after the flare peak. Important plasma downflows were
  identified in the majority of the observed lines, consistent with
  magnetic field reconfiguration. An erupting filament develops at 16:12
  UT and moves rapidly towards the eastern part of the active region.

---------------------------------------------------------
Title: HST/COS FUV Spectrophotometry of the Key Binary Solar Twins
16 Cyg A&amp;B: Astrophysical Laboratories for the Future Sun and
    Older Solar Analogs
Authors: Guinan, Edward F.; Dewarf, Laurence; Engle, Scott G.; Judge,
   Philip G.; Metcalfe, Travis S.
2016hst..prop13861G    Altcode:
  The fortuitous location of the wide G1.5V/G2.5V binary 16 Cyg A&amp;B
  as the brightest stars in the Kepler Field is a "game changer,"
  permitting the determination of the stars' fundamental properties from
  asteroseismolgy analyses. Recent studies returned precise determinations
  of the stars' basic properties including masses and age (6.8+/-0.4 Gyr),
  along with the rotation periods. Thus, 16 Cyg A&amp;B are now the oldest
  solar-mass analogs with reliable ages and physical properties. Only
  the Sun has better determined physical properties. 16 Cyg A&amp;B now
  serve as old-age anchors for Rotation-Age-Activity-Irradiance relations
  (and Gyrochronology studies) for solar-type stars. Extensive Ca II
  HK spectrophotometry reveals low levels of chromospheric emission are
  below the lowest values for our Sun. These stars serve as critical test
  beds for studying solar/stellar dynamos for stars less active than the
  Sun. These advances have catapulted 16 Cyg A&amp;B into a prominent
  place in solar/stellar astrophysics for studying the evolution,
  internal structure, magnetic dynamos, angular momentum loss, and FUV
  irradiances of old solar-mass stars. Although 16 Cyg has been observed
  from X-ray - IR, there are no observations in the FUV region where
  most of the crucial diagnostic chromospheric &amp; transition region
  emissions occur. We request COS FUV medium resolution (G130M, G160M)
  spectra (six orbits/star). This permits the important FUV (1150-1750A)
  line emission strengths, profiles and Doppler shifts to be analyzed
  and compared with the Sun and other solar-analogs. This program is
  complemented by Ca II HK, high precision uvby observations, and by
  proposed Chandra X-ray coronal observations.

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

---------------------------------------------------------
Title: On Helium 1083 nm Line Polarization during the Impulsive
    Phase of an X1 Flare
Authors: Judge, Philip G.; Kleint, Lucia; Sainz Dalda, Alberto
2015ApJ...814..100J    Altcode: 2015arXiv151009218J
  We analyze spectropolarimetric data of the He i 1083 nm multiplet
  (1s2s{}<SUP>3</SUP>{S}<SUB>1</SUB>-1s2p{}<SUP>3</SUP>{P}<SUB>2,1,0</SUB><SUP>o</SUP>)
  during the X1 flare SOL2014-03-29T17:48, obtained with the Facility
  Infrared Spectrometer (FIRS) at the Dunn Solar Telescope. While scanning
  active region NOAA 12017, the FIRS slit crossed a flare ribbon during
  the impulsive phase, when the helium line intensities turned into
  emission at ≲twice the continuum intensity. Their linear polarization
  profiles are of the same sign across the multiplet including 1082.9
  nm, intensity-like, at ≲5% of the continuum intensity. Weaker
  Zeeman-induced linear polarization is also observed. Only the strongest
  linear polarization coincides with hard X-ray (HXR) emission at 30-70
  keV observed by RHESSI. The polarization is generally more extended and
  lasts longer than the HXR emission. The upper J = 0 level of the 1082.9
  nm component is unpolarizable thus, lower-level polarization is the
  culprit. We make non-LTE radiative transfer calculations in thermal
  slabs optimized to fit only intensities. The linear polarizations
  are naturally reproduced, through a systematic change of sign with
  wavelength of the radiation anisotropy when slab optical depths of
  the 1082.9 component are ≲1. Neither are collisions with beams of
  particles needed, nor can they produce the same sign of polarization
  of the 1082.9 and 1083.0 nm components. The He i line polarization
  merely requires heating sufficient to produce slabs of the required
  thickness. Widely different polarizations of Hα, reported previously,
  are explained by different radiative anisotropies arising from slabs
  of different optical depths.

---------------------------------------------------------
Title: UV Spectra, Bombs, and the Solar Atmosphere
Authors: Judge, Philip G.
2015ApJ...808..116J    Altcode: 2015arXiv150608336J
  A recent analysis of UV data from the Interface Region Imaging
  Spectrograph (IRIS) reports plasma “bombs” with temperatures
  near 8 × 10<SUP>4</SUP> K within the solar photosphere. This is a
  curious result, first because most bomb plasma pressures p (the largest
  reported case exceeds 10<SUP>3</SUP> dyn cm<SUP>-2</SUP>) fall well
  below photospheric pressures (\gt 7× {10}<SUP>3</SUP>), and second,
  UV radiation cannot easily escape from the photosphere. In the present
  paper the IRIS data is independently analyzed. I find that the bombs
  arise from plasma originally at pressures between ≤ 80 and 800 dyne
  cm<SUP>-2</SUP> before explosion, i.e., between ≥ 850 and 550 km
  above {τ }<SUB>500</SUB>=1. This places the phenomenon’s origin in
  the low-mid chromosphere or above. I suggest that bomb spectra are
  more compatible with Alfvénic turbulence than with bi-directional
  reconnection jets.

---------------------------------------------------------
Title: Century-long monitoring of solar irradiance and Earth's albedo
    using a stable scattering target in space.
Authors: Judge, P. G.; Egeland, R.
2015MNRAS.448L..90J    Altcode: 2015arXiv150101253J
  An inert sphere of a few metres diameter, placed in a special stable
  geosynchronous orbit in perpetuo, can be used for a variety of
  scientific experiments. Ground-based observations of such a sphere,
  `GeoSphere', can resolve very difficult problems in measuring the
  long-term solar irradiance. GeoSphere measurements will also help us
  understand the evolution of Earth's albedo and climate over at least
  the next century.

---------------------------------------------------------
Title: Photon Mean Free Paths, Scattering, and Ever-Increasing
    Telescope Resolution
Authors: Judge, P. G.; Kleint, L.; Uitenbroek, H.; Rempel, M.;
   Suematsu, Y.; Tsuneta, S.
2015SoPh..290..979J    Altcode: 2014arXiv1409.7866J; 2015SoPh..tmp....3J
  We revisit an old question: what are the effects of observing stratified
  atmospheres on scales below a photon mean free path λ? The mean free
  path of photons emerging from the solar photosphere and chromosphere
  is ≈ 10<SUP>2</SUP> km. Using current 1 m-class telescopes, λ is
  on the order of the angular resolution. But the Daniel K. Inoue Solar
  Telescope will have a diffraction limit of 0.020″ near the atmospheric
  cutoff at 310 nm, corresponding to 14 km at the solar surface. Even
  a small amount of scattering in the source function leads to physical
  smearing due to this solar "fog", with effects similar to a degradation
  of the telescope point spread function. We discuss a unified picture
  that depends simply on the nature and amount of scattering in the
  source function. Scalings are derived from which the scattering in the
  solar atmosphere can be transcribed into an effective Strehl ratio,
  a quantity useful to observers. Observations in both permitted (e.g.,
  Fe I 630.2 nm) and forbidden (Fe I 525.0 nm) lines will shed light on
  both instrumental performance as well as on small-scale structures in
  the solar atmosphere.

---------------------------------------------------------
Title: On the Origin of a Sunquake during the 2014 March 29 X1 Flare
Authors: Judge, Philip G.; Kleint, Lucia; Donea, Alina; Sainz Dalda,
   Alberto; Fletcher, Lyndsay
2014ApJ...796...85J    Altcode: 2014arXiv1409.6268J
  Helioseismic data from the Helioseismic Magnetic Imager instrument have
  revealed a sunquake associated with the X1 flare SOL2014-03-29T17:48
  in active region NOAA 12017. We try to discover if acoustic-like
  impulses or actions of the Lorentz force caused the sunquake. We
  analyze spectropolarimetric data obtained with the Facility Infrared
  Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Fortunately,
  the FIRS slit crossed the flare kernel close to the acoustic source
  during the impulsive phase. The infrared FIRS data remain unsaturated
  throughout the flare. Stokes profiles of lines of Si I 1082.7 nm and He
  I 1083.0 nm are analyzed. At the flare footpoint, the Si I 1082.7 nm
  core intensity increases by a factor of several, and the IR continuum
  increases by 4% ± 1%. Remarkably, the Si I core resembles the classical
  Ca II K line's self-reversed profile. With nLTE radiative models of
  H, C, Si, and Fe, these properties set the penetration depth of flare
  heating to 100 ± 100 km (i.e., photospheric layers). Estimates of the
  non-magnetic energy flux are at least a factor of two less than the
  sunquake energy flux. Milne-Eddington inversions of the Si I line show
  that the local magnetic energy changes are also too small to drive the
  acoustic pulse. Our work raises several questions. Have we missed the
  signature of downward energy propagation? Is it intermittent in time
  and/or non-local? Does the 1-2 s photospheric radiative damping time
  discount compressive modes? <P />The National Center for Atmospheric
  Research is sponsored by the National Science Foundation.

---------------------------------------------------------
Title: A Flare Observed in Coronal, Transition Region, and Helium
    I 10830 Å Emissions
Authors: Zeng, Zhicheng; Qiu, Jiong; Cao, Wenda; Judge, Philip G.
2014ApJ...793...87Z    Altcode: 2014arXiv1408.0236Z
  On 2012 June 17, we observed the evolution of a C-class flare associated
  with the eruption of a filament near a large sunspot in the active
  region NOAA 11504. We obtained high spatial resolution filtergrams
  using the 1.6 m New Solar Telescope at the Big Bear Solar Observatory
  in broadband TiO at 706 nm (bandpass: 10 Å) and He I 10830 Å narrow
  band (bandpass: 0.5 Å, centered 0.25 Å to the blue). We analyze the
  spatio-temporal behavior of the He I 10830 Å data, which were obtained
  over a 90”×90” field of view with a cadence of 10 s. We also analyze
  simultaneous data from the Atmospheric Imaging Assembly and Extreme
  Ultraviolet Variability Experiment instruments on board the Solar
  Dynamics Observatory spacecraft, and data from the Reuven Ramaty High
  Energy Solar Spectroscopic Imager and GOES spacecrafts. Non-thermal
  effects are ignored in this analysis. Several quantitative aspects
  of the data, as well as models derived using the "0D" enthalpy-based
  thermal evolution of loops model code, indicate that the triplet
  states of the 10830 Å multiplet are populated by photoionization of
  chromospheric plasma followed by radiative recombination. Surprisingly,
  the He II 304 Å line is reasonably well matched by standard emission
  measure calculations, along with the C IV emission which dominates
  the Atmosphere Imaging Assembly 1600 Å channel during flares. This
  work lends support to some of our previous work combining X-ray, EUV,
  and UV data of flares to build models of energy transport from corona
  to chromosphere.

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

---------------------------------------------------------
Title: CLE: Coronal line synthesis
Authors: Judge, Philip G.; Casini, Roberto
2014ascl.soft07010J    Altcode:
  CLE, written in Fortran 77, synthesizes Stokes profiles of forbidden
  lines such as Fe XIII 1074.7nm, formed in magnetic dipole transitions
  under coronal conditions. The lines are assumed to be optically thin,
  excited by (anisotropic) photospheric radiation and thermal particle
  collisions.

---------------------------------------------------------
Title: A particular seismic event generated during the solar flare
    2014 March 29
Authors: Donea, Alina C.; Judge, P.; Kleint, L.; Sainz-Dalda, Alberto
2014shin.confE..49D    Altcode:
  The X1.3 solar flare of 2014 March 29 from AR 2017 was extremely well
  observed, from both space and the ground. Helioseismic observations
  from the Helioseismic Magnetic Imager (HMI) aboard the Solar Dynamics
  Observatory (SDO) indicate that this flare generated a weak seismic
  transient. All previous strong seismic transients to date have
  emanated from sunspot penumbrae, but the source of this transient
  lay outside the active-region penumbra close to a magnetic pore. <P
  />Uniquely, Kleint and Sainz Dalda captured ground based imaging
  and slit spectropolarimetry of this flare using the IBIS and FIRS
  instruments respectively, at the Dunn Solar Telescope in Sunspot,
  New Mexico. Here we report only on FIRS data along with space-based
  data, IBIS data will be reported elsewhere. The FIRS infrared data
  are not saturated even during the flare, which was observed through
  the rise and decay phases. We are still investigating the origins of
  peculiar, Zeeman-induced polarization in the He I 1083 nm multiplet. <P
  />Using spectropolarimetric data of Si I and He I lines from FIRS, we
  investigate the evolution of both photosphere and chromosphere above
  and around the seismic source. Together with data from AIA and from
  RHESSI, these data offer unique new insight into how the flare energy
  is channeled into and through the photosphere into the Sun's interior
  as a seismic transient. We present acoustic properties of the seismic
  event and their relationship to photospheric and chromospheric plasma
  and magnetic fields from FIRS, and to the evolving plasmas seen from
  space from UV to X-ray wavelengths.

---------------------------------------------------------
Title: Insights on the solar dynamo from stellar observations
Authors: Egeland, Ricky; Martens, Petrus C.; Judge, Philip G.
2014AAS...22421105E    Altcode:
  A successful dynamo model should not only explain the broad
  characteristics of the magnetic field cycle for the Sun (22-year sunspot
  cycle with polarity reversals, migration of active latitudes toward
  the poles throughout the cycle, and Joy’s law), but should also be
  able to explain the cycling behavior observed in Solar-analog stars,
  which are very close to the Sun in essential characteristics. Our aim
  is to develop a set of constraints on dynamo models from the observed
  behavior of solar-analog stars obtained from a number of long-running
  synoptic surveys of cycling activity (Mount Wilson Observatory HK
  survey, Lowel Observatory Solar-Stellar Spectrograph, and the Fairborn
  Observatory Automatic Photoelectric Telescope survey), in conjuncture
  with stellar rotation and differential rotation data obtained by the
  Kepler Mission and other sources. By carefully piecing together the
  best data available today, we will provide an improved understanding
  of the parameter space in which Solar-like dynamos operate.

---------------------------------------------------------
Title: A FLARE OBSERVED IN CORONAL, TRANSITION REGION AND HELIUM I
    10830 Å EMISSIONS
Authors: Zeng, Zhicheng; Qiu, Jiong; Cao, Wenda; Judge, Philip G.
2014AAS...22412309Z    Altcode:
  On June 17, 2012, we observed the evolution of a C-class flare
  associated with the eruption of a filament near a large sunspot in
  the active region NOAA 11504. We obtained high spatial resolution
  filtergrams using the 1.6 m New Solar Telescope at the Big Bear
  Solar Observatory in TiO broad-band (bandpass: 10 Å)and He I 10830
  Å narrow-band (bandpass: 0.5 Å, centered 0.25 Å to the blue). We
  analyze the spatio-temporal behavior of the He I 10830 Å data, which
  were obtained over a 90×90 arcsends field of view with a cadence
  of 10 sec. We also analyze simultaneous data from the Atmospheric
  Imaging Assembly and Extreme Ultraviolet Variability Experiment
  instruments on board the Solar Dynamics Observatoryspacecraft, and
  data from Reuven Ramaty High Energy Solar Spectroscopic Imager and
  GOES spacecrafts. Several quantitative aspects of the data, as well as
  models derived using the “0D” Enthalpy-Based Thermal Evolution of
  Loops model (EBTEL: Klimchuk et al. 2008) code, indicate that the 10830
  Å multiplet is formed primarily by photoionization of chromospheric
  plasma followed by radiative recombination. Surprisingly, the He II
  304 Å line is reasonably well matched by standard emission measure
  calculations, along with the C IV emission which dominates the AIA
  1600 Å channel during flares. This work lends support to some of our
  previous work combining X-ray, EUV and UV data of flares to buildmodels
  of energy transport from corona to chromosphere.

---------------------------------------------------------
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: Spectropolarimetric Observations of a Small Active Region
    with IBIS
Authors: Tarr, Lucas; Judge, Philip G.
2014AAS...22442204T    Altcode:
  We have used the Interferometric BI--dimensional Spectrograph (IBIS)
  instrument at the Dunn Solar Telescope to measure the polarimetric
  Stokes IQUV signals for the small active region, NOAA 11304. We used
  three lines generally corresponding to three atmospheric heights ranging
  from the photosphere to low corona: Fe I 6302Å, NaI 5896Å, and CaII
  8542Å. Each set of profiles has been inverted using the NICOLE code to
  determine the vector magnetic field at the three heights throughout the
  field of view, or the line--of--sight field, as allowed by the level
  of polarization signal. Comparisons are made between the magnetic and
  thermal structures with the goal of constraining chromospheric models
  with the information obtained at multiple heights.

---------------------------------------------------------
Title: FORWARD: Forward modeling of coronal observables
Authors: Gibson, Sarah E.; Kucera, Therese A.; Casini, Roberto; Dove,
   James; Forland, Blake; Judge, Philip; Rachmeler, Laurel
2014ascl.soft05007G    Altcode: 2014ascl.soft05007F
  FORWARD forward models various coronal observables and can access
  and compare existing data. Given a coronal model, it can produce
  many different synthetic observables (including Stokes polarimetry),
  as well as plots of model plasma properties (density, magnetic field,
  etc.). It uses the CHIANTI database (ascl:9911.004) and CLE polarimetry
  synthesis code, works with numerical model datacubes, interfaces with
  the PFSS module of SolarSoft (ascl:1208.013), includes several analytic
  models, and connects to the Virtual Solar Observatory for downloading
  data in a format directly comparable to model predictions.

---------------------------------------------------------
Title: The Solar Chromosphere Observed at 1 Hz and 0.”2 Resolution
Authors: Lipartito, Isabel; Judge, Philip G.; Reardon, Kevin; Cauzzi,
   Gianna
2014ApJ...785..109L    Altcode: 2014arXiv1401.4474L
  We recently reported extremely rapid changes in chromospheric fine
  structure observed using the IBIS instrument in the red wing of
  Hα. Here, we examine data obtained during the same observing run
  (2010 August 7), of a mature active region NOAA 11094. We analyze
  more IBIS data including wavelength scans and data from the Solar
  Dynamics Observatory, all from within a 30 minute interval. Using a
  slab radiative transfer model, we investigate the physical nature of
  fibrils in terms of tube-like versus sheet-like structures. Principal
  Component Analysis shows that the very rapid Hα variations in the
  line wings depend mostly on changes of line width and line shift,
  but for Ca II 854.2 the variations are dominated by changes in column
  densities. The tube model must be rejected for a small but significant
  class of fibrils undergoing very rapid changes. If our wing data arise
  from the same structures leading to "type II spicules," our analysis
  calls into question much recent work. Instead, the data do not reject
  the hypothesis that some fibrils are optical superpositions of plasma
  collected into sheets. We review how Parker's theory of tangential
  discontinuities naturally leads to plasma collecting into sheets,
  and show that the sheet picture is falsifiable. Chromospheric fine
  structures seem to be populated by both tubes and sheets. We assess the
  merits of spectral imaging versus slit spectroscopy for future studies.

---------------------------------------------------------
Title: From Forbidden Coronal Lines to Meaningful Coronal Magnetic
    Fields
Authors: Judge, P. G.; Habbal, S.; Landi, E.
2013SoPh..288..467J    Altcode: 2013arXiv1304.3863J
  We review methods to measure magnetic fields within the corona using
  the polarized light in magnetic-dipole (M1) lines. We are particularly
  interested in both the global magnetic-field evolution over a solar
  cycle, and the local storage of magnetic free energy within coronal
  plasmas. We address commonly held skepticisms concerning angular
  ambiguities and line-of-sight confusion. We argue that ambiguities are,
  in principle, no worse than more familiar remotely sensed photospheric
  vector fields, and that the diagnosis of M1 line data would benefit
  from simultaneous observations of EUV lines. Based on calculations and
  data from eclipses, we discuss the most promising lines and different
  approaches that might be used. We point to the S-like [Fe XI] line
  (J=2 to J=1) at 789.2 nm as a prime target line (for the Advanced
  Technology Solar Telescope (ATST) for example) to augment the hotter
  1074.7 and 1079.8 nm Si-like lines of [Fe XIII] currently observed by
  the Coronal Multi-channel Polarimeter (CoMP). Significant breakthroughs
  will be made possible with the new generation of coronagraphs, in three
  distinct ways: i) through single-point inversions (which encompasses
  also the analysis of MHD wave modes), ii) using direct comparisons of
  synthetic MHD or force-free models with polarization data, and iii)
  using tomographic techniques.

---------------------------------------------------------
Title: Using large telescopes to answer: why must the Sun have a
    chromosphere and corona?
Authors: Judge, P.; Casini, R.
2012IAUSS...6E.106J    Altcode:
  I will discuss the potential for ground-based telescopes such as
  the ATST to make breakthrough discoveries about the long standing
  mysteries of the solar chromosphere and corona. The biggest advances
  will hinge upon the ability to diagnose magnetic fields through high
  s/n spectropolarimetry.

---------------------------------------------------------
Title: Removal of Spectro-polarimetric Fringes by Two-dimensional
    Pattern Recognition
Authors: Casini, R.; Judge, P. G.; Schad, T. A.
2012ApJ...756..194C    Altcode: 2012arXiv1208.5104C
  We present a pattern-recognition-based approach to the problem of
  the removal of polarized fringes from spectro-polarimetric data. We
  demonstrate that two-dimensional principal component analysis can
  be trained on a given spectro-polarimetric map in order to identify
  and isolate fringe structures from the spectra. This allows us,
  in principle, to reconstruct the data without the fringe component,
  providing an effective and clean solution to the problem. The results
  presented in this paper point in the direction of revising the way
  that science and calibration data should be planned for a typical
  spectro-polarimetric observing run.

---------------------------------------------------------
Title: Analysis of Seeing-induced Polarization Cross-talk and
    Modulation Scheme Performance
Authors: Casini, R.; de Wijn, A. G.; Judge, P. G.
2012ApJ...757...45C    Altcode: 2011arXiv1107.0367C
  We analyze the generation of polarization cross-talk in Stokes
  polarimeters by atmospheric seeing, and its effects on the noise
  statistics of spectropolarimetric measurements for both single-beam
  and dual-beam instruments. We investigate the time evolution of
  seeing-induced correlations between different states of one modulation
  cycle and compare the response to these correlations of two popular
  polarization modulation schemes in a dual-beam system. Extension of
  the formalism to encompass an arbitrary number of modulation cycles
  enables us to compare our results with earlier work. Even though we
  discuss examples pertinent to solar physics, the general treatment
  of the subject and its fundamental results might be useful to a wider
  community.

---------------------------------------------------------
Title: Confronting a solar irradiance reconstruction with solar and
    stellar data
Authors: Judge, P. G.; Lockwood, G. W.; Radick, R. R.; Henry, G. W.;
   Shapiro, A. I.; Schmutz, W.; Lindsey, C.
2012A&A...544A..88J    Altcode:
  Context. A recent paper by Shapiro and colleagues (2011, A&amp;A,
  529, A67) reconstructs spectral and total irradiance variations of
  the Sun during the holocene. Aims. In this note, we comment on why
  their methodology leads to large (0.5%) variations in the solar TSI on
  century-long time scales, in stark contrast to other reconstructions
  which have ∼ 0.1% variations. Methods. We examine the amplitude
  of the irradiance variations from the point of view of both solar
  and stellar data. Results. Shapiro et al.'s large amplitudes arise
  from differences between the irradiances computed from models A and C
  of Fontenla and colleagues, and from their explicit assumption that
  the radiances of the quiet Sun vary with the cosmic ray modulation
  potential. We suggest that the upper photosphere, as given by model A,
  is too cool, and discuss relative contributions of local vs. global
  dynamos to the magnetism and irradiance of the quiet Sun. We compare
  the slow (&gt;22 yr) components of the irradiance reconstructions with
  secular changes in stellar photometric data that span 20 years or less,
  and find that the Sun, if varying with such large amplitudes, would
  still lie within the distribution of stellar photometric variations
  measured over a 10-20 year period. However, the stellar time series
  are individually too short to see if the reconstructed variations will
  remain consistent with stellar variations when observed for several
  decades more. Conclusions. By adopting model A, Shapiro et al. have
  over-estimated quiet-Sun irradiance variations by about a factor of
  two, based upon a re-analysis of sub-mm data from the James Clerk
  Maxwell telescope. But both estimates are within bounds set by current
  stellar data. It is therefore vital to continue accurate photometry of
  solar-like stars for at least another decade, to reveal secular and
  cyclic variations on multi-decadal time scales of direct interest to
  the Sun.

---------------------------------------------------------
Title: Evidence for Sheet-like Elementary Structures in the Sun's
    Atmosphere?
Authors: Judge, Philip G.; Reardon, Kevin; Cauzzi, Gianna
2012ApJ...755L..11J    Altcode:
  Narrow, thread-like structures in the Sun's chromosphere are currently
  understood to be plasma guided along narrow tubes of magnetic flux. We
  report on 1 s cadence imaging spectroscopic measurements of the Hα
  line with the IBIS Fabry-Pérot instrument at the Dunn Solar Telescope,
  obtained +0.11 nm from line center. Rapid changes grossly exceeding
  the Alfvén speed are commonly seen along the full extent of many
  chromospheric threads. We argue that only an optical superposition
  effect can reasonably explain the data, analogous to striations of
  curtains blowing in the wind. Other explanations appear to require
  significant contrivances to avoid contradicting various aspects of
  the data. We infer that the absorbing plasma exists in two-dimensional
  sheet-like structures within the three-dimensional magnetofluid, related
  perhaps to magnetic tangential discontinuities. This interpretation
  demands a re-evaluation of basic assumptions about low-β solar plasmas,
  as advocated by Parker, with broader implications in astrophysics
  and plasma physics. Diverse, high-cadence observations are needed to
  further define the relationship between magnetic field and thermal
  fine structure.

---------------------------------------------------------
Title: Solar and stellar activity: diagnostics and indices
Authors: Judge, Philip G.; Thompson, Michael J.
2012IAUS..286...15J    Altcode: 2012arXiv1201.4625J
  We summarize the fifty-year concerted effort to place the “activity”
  of the Sun in the context of the stars. As a working definition of solar
  activity in the context of stars, we adopt those globally-observable
  variations on time scales below thermal time scales, of ~10<SUP>5</SUP>
  yr for the convection zone. So defined, activity is dominated by
  magnetic-field evolution, including the 22-year Hale cycle, the typical
  time it takes for the quasi-periodic reversal in which the global
  magnetic-field takes place. This is accompanied by sunspot variations
  with 11 year periods, known since the time of Schwabe, as well as faster
  variations due to rotation of active regions and flaring. “Diagnostics
  and indices” are terms given to the indirect signatures of varying
  magnetic-fields, including the photometric (broad-band) variations
  associated with the sunspot cycle, and variations of the accompanying
  heated plasma in higher layers of stellar atmospheres seen at special
  optical wavelengths, and UV and X-ray wavelengths. Our attention is
  also focussed on the theme of the Symposium by examining evidence for
  deep and extended minima of stars, and placing the 70-year long solar
  Maunder Minimum into a stellar context.

---------------------------------------------------------
Title: Spectropolarimetry of a Limb Active Region and its Cool
    Coronal Structures
Authors: Judge, Philip G.; Kleint, L.; Casini, R.; Schad, T.
2012AAS...22052119J    Altcode:
  During the SDO mission we have regularly used the IBIS and FIRS
  spectropolarimeters at the Dunn Solar Telescope to measure magnetic
  fields and plasma parameters from photosphere up to the coronal
  base. Here we analyze data of a region at and above the east limb (later
  named NOAA 11302) obtained on September 22nd 2011. The measurements
  show an erupting prominence, remarkably uniform cool plumes and some
  material seemingly draining into the active region along post-flare
  loops. The imaging Fabry-Perot instrument IBIS obtained 30 scans of
  intensity spectra (30s cadence) and 40 scans of Stokes parameters
  (90s cadence) in lines of Fe I 630 nm, Na I 596 nm, Ca II 852 nm and
  H-alpha 656 nm, with an angular resolution near 0.2", over a 40"x80"
  field of view. The FIRS slit was scanned across the solar image to
  obtain Stokes profiles including lines of Si I 1028.7 nm and He I 1083
  nm. We obtained 3 FIRS scans covering a 90"x75" area with cadences of
  between half an hour and an hour simultaneously with IBIS, at a lower
  angular resolution. Simultaneous broad band Ca II K and G-band data
  were obtained with a cadence of 5s. We discuss the vector magnetic
  fields and plasma properties of NOAA 11302, with emphasis on cool <P
  />plasma structures extending many Mm into the corona.

---------------------------------------------------------
Title: Radiating Current Sheets in the Solar Chromosphere
Authors: Goodman, Michael L.; Judge, Philip G.
2012ApJ...751...75G    Altcode: 2014arXiv1406.1211G
  An MHD model of a hydrogen plasma with flow, an energy equation,
  NLTE ionization and radiative cooling, and an Ohm's law with
  anisotropic electrical conduction and thermoelectric effects
  is used to self-consistently generate atmospheric layers over a
  50 km height range. A subset of these solutions contains current
  sheets and has properties similar to those of the lower and middle
  chromosphere. The magnetic field profiles are found to be close to
  Harris sheet profiles, with maximum field strengths ~25-150 G. The
  radiative flux F<SUB>R</SUB> emitted by individual sheets is ~4.9 ×
  10<SUP>5</SUP>-4.5 × 10<SUP>6</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>,
  to be compared with the observed chromospheric emission rate of
  ~10<SUP>7</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>. Essentially all
  emission is from regions with thicknesses ~0.5-13 km containing the
  neutral sheet. About half of F<SUB>R</SUB> comes from sub-regions with
  thicknesses 10 times smaller. A resolution &lt;~ 5-130 m is needed to
  resolve the properties of the sheets. The sheets have total H densities
  ~10<SUP>13</SUP>-10<SUP>15</SUP> cm<SUP>-3</SUP>. The ionization
  fraction in the sheets is ~2-20 times larger, and the temperature is
  ~2000-3000 K higher than in the surrounding plasma. The Joule heating
  flux F<SUB>J</SUB> exceeds F<SUB>R</SUB> by ~4%-34%, the difference
  being balanced in the energy equation mainly by a negative compressive
  heating flux. Proton Pedersen current dissipation generates ~62%-77%
  of the positive contribution to F<SUB>J</SUB> . The remainder of this
  contribution is due to electron current dissipation near the neutral
  sheet where the plasma is weakly magnetized.

---------------------------------------------------------
Title: Radiating Current Sheets in the Solar Chromosphere
Authors: Goodman, Michael L.; Judge, P. G.
2012AAS...22052116G    Altcode:
  An MHD model of a Hydrogen plasma with flow, an energy equation,
  NLTE ionization and radiative cooling, and an Ohm's law with
  anisotropic electrical conduction and thermoelectric effects is used
  to self-consistently generate atmospheric layers over a 50 km height
  range. A subset of these solutions contain current sheets, and have
  properties similar to those of the lower and middle chromosphere. The
  magnetic field profiles are found to be close to Harris sheet profiles,
  with maximum field strengths 25-150 G. The radiative flux F_R emitted
  by individual sheets is 4.9 x 10^5 - 4.5 x 10^6 ergs-cm^{-2}-s^{-1},
  to be compared with the observed chromospheric emission rate of 10^7
  ergs-cm^{-2}-s^{-1}. Essentially all emission is from regions with
  thicknesses 0.5 - 13 km containing the neutral sheet. About half of F_R
  comes from sub-regions with thicknesses 10 times smaller. A resolution
  &lt; 5-130 m is needed to resolve the properties of the sheets. The
  sheets have total H densities 10^{13}-10^{15} cm^{-3}. The ionization
  fraction in the sheets is 2-20 times larger, and the temperature is
  2000-3000 K higher than in the surrounding plasma. The Joule heating
  flux F_J exceeds F_R by 4-34 %, the difference being balanced
  in the energy equation mainly by a negative compressive heating
  flux. Proton Pedersen current dissipation generates 62-77 % of the
  positive contribution to F_J. The remainder of this contribution
  is due to electron current dissipation near the neutral sheet where
  the plasma is weakly magnetized. These solutions represent the first,
  first principles theoretical proof of the existence of radiating current
  sheets under chromospheric conditions. The existence of these solutions
  suggests the existence of sub-resolution, horizontal current sheets
  in the chromosphere that are sites of strong Joule heating driven
  radiative emission.

---------------------------------------------------------
Title: Key- or tomb- stones in the bridge from photosphere to corona?
Authors: Judge, Philip G.
2012decs.confE..28J    Altcode:
  The Sun's atmosphere must get from photospheric pressures of 10(5)
  dyn cm(-2) , where gas pressures and Reynolds stresses dominate, to
  coronal pressures of 10(-1) dyne cm(-2) , where magnetic stresses become
  dominant, within a mere 2000km. Outside of sunspots, the photospheric
  boundary layer exhibits hydrodynamic turbulent structure. The low
  pressure chromosphere- corona transition, while poorly understood,
  is clearly ordered by magnetic fields. Across the intervening scale
  heights, the richness of coupled magneto- hydrodynamics in a partially
  ionized atmosphere out of LTE, within which ions become magnetized,
  somehow leads to what we observe as the "magnetic chromosphere". We
  understand only the overall thermal structure of the chromosphere,
  it behaves as a thermostat: in response to heating energy is stored
  in latent heat of ionization and lost to radiation. But in terms of
  the magnetic structure, we must deal with: interaction with the plasma
  including multi-fluid effects, especially ion-neutral damping; effects
  of stratification on coupling wave modes; the existence of weak,
  discontinuous solutions to the MHD equations (current sheets). To
  generate discussion, I will argue that we have little idea what the
  chromosphere does to the incoming flux of EM energy from beneath,
  and that current generations of MHD models are far from providing
  this understanding. We must not let apparent "successes" of, e.g.,
  potential field models on large scales seduce us into thinking we
  understand how the Sun makes the photosphere-corona transition.

---------------------------------------------------------
Title: The Connection of Type II Spicules to the Corona
Authors: Judge, Philip G.; de Pontieu, Bart; McIntosh, Scott W.;
   Olluri, Kosovare
2012ApJ...746..158J    Altcode: 2011arXiv1112.6174D; 2011arXiv1112.6174J
  We examine the hypothesis that plasma associated with "Type II"
  spicules is heated to coronal temperatures, and that the upward
  moving hot plasma constitutes a significant mass supply to the solar
  corona. One-dimensional hydrodynamical models including time-dependent
  ionization are brought to bear on the problem. These calculations
  indicate that heating of field-aligned spicule flows should produce
  significant differential Doppler shifts between emission lines formed
  in the chromosphere, transition region, and corona. At present,
  observational evidence for the computed 60-90 km s<SUP>-1</SUP>
  differential shifts is weak, but the data are limited by difficulties
  in comparing the proper motion of Type II spicules with spectral
  and kinematic properties of an associated transition region and
  coronal emission lines. Future observations with the upcoming infrared
  interferometer spectrometer instrument should clarify if Doppler shifts
  are consistent with the dynamics modeled here.

---------------------------------------------------------
Title: Spectropolarimetry Of The Footpoints Of A C-class Flare In
    The Chromosphere
Authors: Kleint, Lucia; Judge, P.
2011SPD....42.0308K    Altcode: 2011BAAS..43S.0308K
  Flares are well-known solar phenomena but have rarely been
  imaged in high resolution polarimetry and even less often in the
  chromosphere. We observed the declining phase of a C-class flare in
  NOAA 10940 on January 29, 2007 with the IBIS instrument (0.17"/px),
  taking quasi-simultaneous spectropolarimetric images in the chromosphere
  (8542 [[Unable to Display Character: &amp;#506]]) and in the photosphere
  (6302 [[Unable to Display Character: &amp;#506]]). <P />Only the inner
  wings and core of the chromospheric line are seen to brighten in IBIS,
  the underlying photosphere remaining undisturbed. TRACE images reveal
  the connectivity of the chromospheric flaring plasma to the overlying
  corona: IBIS fortuitously captured the chromospheric flares associated
  with both footpoints of a loop systems seen in TRACE. <P />Our hour-long
  image sequence shows the evolution and weakening of the chromospheric
  flare, and reveals unresolved opposite magnetic field components with
  large velocities with respect to the average Sun. In the chromosphere,
  we find redshifted components but in the photosphere we see observe
  blueshifts. We will present high resolution movies of the flaring
  plasma seen in both footpoints of the loop system. We will discuss the
  implications of these measurements for models of the storage and release
  of energy for this class of small flare, and possible connections to
  the formation of the penumbra that appears later at this location.

---------------------------------------------------------
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: Thermal Fine Structure and Magnetic Fields in the Solar
Atmosphere: Spicules and Fibrils
Authors: Judge, Philip G.; Tritschler, Alexandra; Chye Low, Boon
2011ApJ...730L...4J    Altcode: 2011arXiv1102.1517J
  The relationship between observed structures in the solar atmosphere
  and the magnetic fields threading them is known only for the solar
  photosphere, even then imprecisely. We suggest that some of the fine
  structures in the more tenuous chromosphere and corona—specifically
  some populations of spicules and fibrils—correspond to warps
  in two-dimensional sheet-like structures, as an alternative to
  conventional interpretations in terms of tube-like structures. The
  sheets are perhaps related to magnetic tangential discontinuities,
  which Parker has argued arise naturally in low-β conditions. Some
  consequences of this suggestion, if it can be confirmed, are discussed.

---------------------------------------------------------
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: Magnetic Field Measurements at the Photosphere and Coronal Base
Authors: Judge, P. G.; Centeno, R.; Tritschler, A.; Uitenbroek, H.;
   Jaeggli, S.; Lin, H.
2010AGUFMSH31A1783J    Altcode:
  We have obtained vector polarimetric measurements in lines of Fe I
  (630nm), Ca II (854nm) and He I (1083nm) of several active regions
  during 3-14 June 2010. The measurements were made at the Dunn Solar
  Telescope at Sacramento Peak Observatory, using the FIRS and IBIS
  instruments simultaneously. We discuss these and SDO data for NOAA
  11076. The seeing was very good or excellent and the adaptive
  optics system functioned well. In this preliminary analysis we
  compare extrapolations of photospheric fields with the constraints
  available from Stokes polarimetry, including the morphology and
  kinematic properties of fibrils. Connections to the corona will also be
  discussed. The implications for field extrapolations from photospheric
  measurements will be discussed. We will make the reduced data freely
  available on the web for interested researchers.

---------------------------------------------------------
Title: Discovery of a 1.6 Year Magnetic Activity Cycle in the
    Exoplanet Host Star ι Horologii
Authors: Metcalfe, T. S.; Basu, S.; Henry, T. J.; Soderblom, D. R.;
   Judge, P. G.; Knölker, M.; Mathur, S.; Rempel, M.
2010ApJ...723L.213M    Altcode: 2010arXiv1009.5399M
  The Mount Wilson Ca HK survey revealed magnetic activity variations in
  a large sample of solar-type stars with timescales ranging from 2.5
  to 25 years. This broad range of cycle periods is thought to reflect
  differences in the rotational properties and the depths of the surface
  convection zones for stars with various masses and ages. In 2007, we
  initiated a long-term monitoring campaign of Ca II H and K emission
  for a sample of 57 southern solar-type stars to measure their magnetic
  activity cycles and their rotational properties when possible. We report
  the discovery of a 1.6 year magnetic activity cycle in the exoplanet
  host star ι Horologii and obtain an estimate of the rotation period
  that is consistent with Hyades membership. This is the shortest activity
  cycle so far measured for a solar-type star and may be related to the
  short-timescale magnetic variations recently identified in the Sun
  and HD 49933 from helioseismic and asteroseismic measurements. Future
  asteroseismic observations of ι Hor can be compared to those obtained
  near the magnetic minimum in 2006 to search for cycle-induced shifts in
  the oscillation frequencies. If such short activity cycles are common
  in F stars, then NASA's Kepler mission should observe their effects
  in many of its long-term asteroseismic targets.

---------------------------------------------------------
Title: A Chromospheric Conundrum?
Authors: Judge, Philip; Knölker, Michael; Schmidt, Wolfgang;
   Steiner, Oskar
2010ApJ...720..776J    Altcode: 2010arXiv1007.1203J
  We examine spectra of the Ca II H line, obtained under good seeing
  conditions with the VTT Echelle Spectrograph in 2007 June, and
  higher resolution data of the Ca II λ8542 line from Fabry-Pérot
  instruments. The VTT targets were areas near disk center which included
  quiet Sun and some dispersed plage. The infrared data included quiet
  Sun and plage associated with small pores. Bright chromospheric network
  emission patches expand little with wavelength from line wing to line
  center, i.e., with increasing line opacity and height. We argue that
  this simple observation has implications for the force and energy
  balance of the chromosphere, since bright chromospheric network
  emission is traditionally associated with enhanced local mechanical
  heating which increases temperatures and pressures. Simple physical
  considerations then suggest that the network chromosphere may not be
  able to reach horizontal force balance with its surroundings, yet the
  network is a long-lived structure. We speculate on possible reasons for
  the observed behavior. By drawing attention to a potential conundrum,
  we hope to contribute to a better understanding of a long-standing
  unsolved problem: the heating of the chromospheric network.

---------------------------------------------------------
Title: On the Solar Chromosphere Observed at the LIMB with Hinode
Authors: Judge, Philip G.; Carlsson, Mats
2010ApJ...719..469J    Altcode: 2010arXiv1004.1398J
  Broadband images in the Ca II H line, from the Broadband Filter Imager
  (BFI) instrument on the Hinode spacecraft, show emission from spicules
  emerging from and visible right down to the observed limb. Surprisingly,
  little absorption of spicule light is seen along their lengths. We
  present formal solutions to the transfer equation for given (ad hoc)
  source functions, including a stratified chromosphere from which
  spicules emanate. The model parameters are broadly compatible with
  earlier studies of spicules. The visibility of Ca II spicules down
  to the limb in Hinode data seems to require that spicule emission
  be Doppler shifted relative to the stratified atmosphere, either by
  supersonic turbulent or organized spicular motion. The non-spicule
  component of the chromosphere is almost invisible in the broadband BFI
  data, but we predict that it will be clearly visible in high spectral
  resolution data. Broadband Ca II H limb images give the false impression
  that the chromosphere is dominated by spicules. Our analysis serves
  as a reminder that the absence of a signature can be as significant
  as its presence.

---------------------------------------------------------
Title: Magnetic field measurements at the photosphere and coronal base
Authors: Judge, Philip; Centeno, R.; Tritschler, A.; Uitenbroek, H.;
   Jaeggli, S.; Lin, H.
2010shin.confE..56J    Altcode:
  We have obtained vector polarimetric measurements in lines of Fe I
  (630nm), Ca II (854nm) and He I (1083) of several active regions during
  3-14 June 2010. The measurements were made at the Dunn Solar Telescope
  at Sacramento Peak Observatory, using the FIRS and IBIS instruments
  simultaneously. We discuss data for NOAA 11076 observed on 4 June
  2010. The seeing was very good or excellent and the adaptive optics
  system functioned well. In this preliminary analysis we compare linear
  extrapolations of photospheric fields with the constraints available
  from Stokes polarimetry, including the morphology and kinematic
  properties of fibrils. The implications for field extrapolations from
  photospheric measurements will be discussed. We will make the reduced
  data freely available on the web for interested researchers.

---------------------------------------------------------
Title: Forward modeling of spectropolarimetric data to interpret
    coronal magnetic features
Authors: Rachmeler, Laurel A.; Gibson, S. E.; Dove, J.; Judge, P. G.
2010shin.confE..53R    Altcode:
  We present a forward model that creates various forms of coronal
  observational data from simulated systems. Along with plane of
  sky parameter slices and integrated emission images, this model
  calculates the full Stokes vectors from forbidden infrared lines. It
  is clear that photospheric magnetograph data is not sufficient to
  ascertain coronal magnetic fields. The coronal Stokes vectors provide
  additional information about the magnetic morphology above the solar
  limb, specifically the relative strength of the integrated plane of
  sky and line of sight field. Our forward model helps to determine
  which physical features can be identified in the observations as a
  specific component of a theoretical model, without requiring a full
  3D inversion of the Stokes profiles. We have found that flux ropes
  are theoretically identifiable in the simulated data, and we use this
  technique to explore the disambiguation of pre-CME filament structure.

---------------------------------------------------------
Title: Historical Eclipses and the Recent Solar Minimum Corona
Authors: Judge, P. G.; Burkepile, J.; de Toma, G.; Druckmüller, M.
2010ASPC..428..171J    Altcode: 2010arXiv1001.5278J
  We have studied the corona as seen at the eclipses of 1878, 1900, 1901,
  and others. These eclipses occurred during extended sunspot minimum
  conditions. We compare these data with those of the recent solar minimum
  corona, using data from the eclipses of July 22, 2009 and August 1,
  2008. An attempt to characterize the global solar magnetic fields is
  made. We speculate on the origin of the non-dipolar structure seen in
  the 2008 and 2009 eclipse images.

---------------------------------------------------------
Title: Fabry-Pérot Versus Slit Spectropolarimetry of Pores and
Active Network: Analysis of IBIS and Hinode Data
Authors: Judge, Philip G.; Tritschler, Alexandra; Uitenbroek, Han;
   Reardon, Kevin; Cauzzi, Gianna; de Wijn, Alfred
2010ApJ...710.1486J    Altcode: 2010arXiv1001.0561J
  We discuss spectropolarimetric measurements of photospheric (Fe I
  630.25 nm) and chromospheric (Ca II 854.21 nm) spectral lines in and
  around small magnetic flux concentrations, including a pore. Our
  long-term goal is to diagnose properties of the magnetic field
  near the base of the corona. We compare ground-based two-dimensional
  spectropolarimetric measurements with (almost) simultaneous space-based
  slit spectropolarimetry. We address the question of noise and crosstalk
  in the measurements and attempt to determine the suitability of Ca II
  measurements with imaging spectropolarimeters for the determination
  of chromospheric magnetic fields. The ground-based observations
  were obtained 2008 May 20, with the Interferometric Bidimensional
  Spectrometer (IBIS) in spectropolarimetric mode operated at the Dunn
  Solar Telescope at Sunspot, NM. The space observations were obtained
  with the Spectro-Polarimeter of the Solar Optical Telescope aboard the
  Japanese Hinode satellite. The agreement between the near-simultaneous
  co-spatial IBIS and Hinode Stokes-V profiles at 630.25 nm is
  excellent, with V/I amplitudes compatible to within 1%. The IBIS QU
  measurements are affected by residual crosstalk from V, arising from
  calibration inaccuracies, not from any inherent limitation of imaging
  spectroscopy. We use a Principal Component Analysis to quantify the
  detected crosstalk. QU profiles with V crosstalk subtracted are in
  good agreement with the Hinode measurements, but are noisier owing to
  fewer collected photons. Chromospheric magnetic fields are notoriously
  difficult to constrain by polarization of Ca II lines alone. However,
  we demonstrate that high cadence, high angular resolution monochromatic
  images of fibrils in Ca II and Hα, seen clearly in IBIS observations,
  can be used to improve the magnetic field constraints, under conditions
  of high electrical conductivity. Such work is possible only with time
  series data sets from two-dimensional spectroscopic instruments such
  as IBIS, under conditions of good seeing.

---------------------------------------------------------
Title: Coronal Emission Lines as Thermometers
Authors: Judge, Philip G.
2010ApJ...708.1238J    Altcode: 2009arXiv0911.4085J
  Coronal emission-line intensities are commonly used to measure electron
  temperatures using emission measure and/or line ratio methods. In the
  presence of systematic errors in atomic excitation calculations and
  data noise, the information on underlying temperature distributions
  is fundamentally limited. Increasing the number of emission lines
  used does not necessarily improve the ability to discriminate between
  different kinds of temperature distributions.

---------------------------------------------------------
Title: The chromosphere: gateway to the corona? ...Or the purgatory
    of solar physics?
Authors: Judge, P. G.
2010MmSAI..81..543J    Altcode:
  I argue that one should attempt to understand the solar chromosphere not
  only for its own sake, but also if one is interested in the physics of:
  the corona; astrophysical dynamos; space weather; partially ionized
  plasmas; heliospheric UV radiation; the transition region. I outline
  curious observations which I personally find puzzling and deserving
  of attention.

---------------------------------------------------------
Title: Activity Cycles of Southern Asteroseismic Targets
Authors: Metcalfe, Travis S.; Judge, P. G.; Basu, S.; Henry, T. J.;
   Soderblom, D. R.; Knoelker, M.; Rempel, M.
2010AAS...21542416M    Altcode: 2010BAAS...42..333M
  The Mount Wilson Ca HK survey revealed magnetic activity variations in
  a large sample of solar-type stars with timescales ranging from 2.5
  to 25 years. This broad range of cycle periods is thought to reflect
  differences in the rotational properties and the depths of the surface
  convection zones for stars with various masses and ages. Asteroseismic
  data will soon provide direct measurements of these quantities for
  individual stars, but many of the most promising targets are in the
  southern sky (e.g., alpha Cen A &amp; B, beta Hyi, mu Ara, tau Cet,
  nu Ind), while long-term magnetic activity cycle surveys are largely
  confined to the north. In 2007 we began using the SMARTS 1.5-m telescope
  to conduct a long-term monitoring campaign of Ca II H &amp; K emission
  for a sample of 57 southern solar-type stars to measure their magnetic
  activity cycles and their rotational properties when possible. This
  sample includes the most likely southern asteroseismic targets to be
  observed by the Stellar Oscillations Network Group (SONG), currently
  scheduled to begin operations in 2012. We present selected results from
  the first two years of the survey, and from the longer time baseline
  sampled by a single-epoch survey conducted in 1992.

---------------------------------------------------------
Title: New Perspectives on the Photosphere/Corona Interface (Keynote)
Authors: Judge, P. G.
2009ASPC..415....7J    Altcode:
  I review the role of the chromosphere as the lower boundary for the
  corona. I highlight the need for measurements of the chromospheric
  magnetic field as the plasma regimes change from β &gt;1 to &lt;1,
  using a striking observational example. I also review some physical
  processes which can alter the magnetic free energy as it traverses the
  chromosphere. Multi-fluid effects appear to be important in determining
  the supply of mass, momentum and energy into the overlying corona. Such
  effects have been only partly studied in the literature. I re-iterate
  the obvious conclusion, often ignored, that one must understand specific
  chromospheric processes if one is to have hope of addressing the nature
  of the supply of mass, momentum, and energy into the corona.

---------------------------------------------------------
Title: Activity Cycles of Southern Asteroseismic Targets
Authors: Metcalfe, T. S.; Judge, P. G.; Basu, S.; Henry, T. J.;
   Soderblom, D. R.; Knoelker, M.; Rempel, M.
2009arXiv0909.5464M    Altcode:
  The Mount Wilson Ca HK survey revealed magnetic activity variations in
  a large sample of solar-type stars with timescales ranging from 2.5
  to 25 years. This broad range of cycle periods is thought to reflect
  differences in the rotational properties and the depths of the surface
  convection zones for stars with various masses and ages. Asteroseismic
  data will soon provide direct measurements of these quantities for
  individual stars, but many of the most promising targets are in the
  southern sky (e.g., alpha Cen A &amp; B, beta Hyi, mu Ara, tau Cet,
  nu Ind), while long-term magnetic activity cycle surveys are largely
  confined to the north. In 2007 we began using the SMARTS 1.5-m telescope
  to conduct a long-term monitoring campaign of Ca II H &amp; K emission
  for a sample of 57 southern solar-type stars to measure their magnetic
  activity cycles and their rotational properties when possible. This
  sample includes the most likely southern asteroseismic targets to be
  observed by the Stellar Oscillations Network Group (SONG), currently
  scheduled to begin operations in 2012. We present selected results from
  the first two years of the survey, and from the longer time baseline
  sampled by a single-epoch survey conducted in 1992.

---------------------------------------------------------
Title: Mining a Massive Brightpoint Database for Science
Authors: McIntosh, Scott W.; Sitongia, L.; Markel, R.; Judge, P. G.;
   Davey, A. R.
2009SPD....40.1525M    Altcode:
  We update the analysis of McIntosh &amp; Gurman [2005, Sol. Phys.,
  228, 285] to incorporate changes to the automatic EUV Bright Point
  (BP) detection algorithm of data from the Extreme-ultraviolet
  Imaging Telescope (EIT) on the Solar and Heliospheric Observatory
  (SOHO). We discuss the implementation of the BP catalog as a searchable
  database for the community and some of the basic manipulations on
  that database. We present the multi-wavelength differential rotation
  rates for the previous solar cycle and make an initial foray into the
  connection of this most ubiquitous coronal structure and the larger
  scale magnetic dynamo.

---------------------------------------------------------
Title: On magnetic field “reconstruction”
Authors: Judge, P. G.
2009A&A...493.1121J    Altcode:
  Context: Solanki and colleagues have presented intriguing 3D
  “reconstructions” of magnetic fields from the vector polarimetry
  of the He I 1083 nm multiplet. <BR />Aims: In this Research Note I
  re-examine the reconstruction technique used. <BR />Methods: Using
  a simple dipole field, I examine the reconstruction technique as
  applied to the theoretical fields. I assume that the He line forms in
  two locations, (1) along the magnetic loops and (2) in a horizontal
  plane. <BR />Results: The planar interpretation can account for all
  aspects of the data, but the loop interpretation has geometrical and
  physical problems. <BR />Conclusions: The data by themselves are not
  sufficient to determine which picture is more applicable. Nevertheless
  I argue that the planar interpretation makes more physical sense and
  that the early reconstructions lead to spurious results. I suggest
  additional tests that might help constrain the problem further.

---------------------------------------------------------
Title: The Solar Chromosphere: Old Challenges, New Frontiers
Authors: Ayres, T.; Uitenbroek, H.; Cauzzi, G.; Reardon, K.; Berger,
   T.; Schrijver, C.; de Pontieu, B.; Judge, P.; McIntosh, S.; White,
   S.; Solanki, S.
2009astro2010S...9A    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Physics of the chromosphere and the lower coronal boundary
    conditions
Authors: Judge, P.
2008AGUFMSH51C..03J    Altcode:
  I will review observations and theoretical work concerning the role
  of the chromosphere as the lower boundary for the corona. I will
  highlight the need for measurements of the chromospheric magnetic
  field as the plasma regimes change from beta &gt; 1 to &lt; 1, using
  a striking observational example. I will review some of the important
  physical processes occurring within the partially ionized chromosphere
  which can greatly alter the conditions at the coronal base from those
  expected based only upon photospheric measurements. I will re-iterate
  the obvious conclusion, but one often ignored, that one must understand
  specific chromospheric processes if one is to have hope of addressing
  the nature of the supply of mass, momentum and energy into the corona.

---------------------------------------------------------
Title: On the Magnetic Structure of the Solar Transition Region
Authors: Judge, Philip; Centeno, Rebecca
2008ApJ...687.1388J    Altcode: 2008arXiv0805.1436J
  We examine the hypothesis that cool loops dominate emission from solar
  transition region plasma below temperatures of 2 × 10<SUP>5</SUP>
  K. We compare published VAULT images of H Lyα, a lower transition
  region line, with nearly contemporaneous magnetograms from Kitt Peak,
  obtained during the second flight (VAULT-2) on 2002 June 14. The
  measured surface fields and potential extrapolations suggest that there
  are too few short loops and that Lyα emission is associated with
  the base regions of longer, coronal loops. VAULT-2 data of network
  boundaries have an asymmetry on scales larger than supergranules,
  also indicating an association with long loops. We complement the
  Kitt Peak data with very sensitive vector polarimetric data from the
  spectropolarimeter on board Hinode to determine the influence of very
  small magnetic concentrations on our analysis. From these data, two
  classes of behavior are found. Within the cores of strong magnetic
  flux concentrations (&gt;5 × 10<SUP>18</SUP> Mx) associated with
  active network and plage, small-scale mixed fields are absent, and
  any short loops can connect just the peripheries of the flux to cell
  interiors. Core fields return to the surface via longer, most likely
  coronal, loops. In weaker concentrations, short loops can connect
  concentrations and produce mixed fields within network boundaries,
  as suggested by Dowdy and colleagues. The VAULT-2 data that we
  examined are associated with strong concentrations. We conclude that
  the cool-loop model applies only to a small fraction of the VAULT-2
  emission, but we cannot discount a significant role for cool loops in
  quieter regions. We suggest a physical picture for how network Lyα
  emission may occur through the cross-field diffusion of neutral atoms
  from chromospheric into coronal plasma.

---------------------------------------------------------
Title: An Explanation of the Solar Transition Region
Authors: Judge, Philip
2008ApJ...683L..87J    Altcode: 2008arXiv0807.1706J
  Prompted by high-resolution observations, I propose an explanation
  for the 40+ year old problem of structure and energy balance in
  the solar transition region. The ingredients are simply cross-field
  diffusion of neutral atoms from cool threads extending into the corona,
  and the subsequent excitation, radiation, and ionization of these
  atoms via electron impact. The processes occur whenever chromospheric
  plasma is adjacent to coronal plasma, and are efficient even when ion
  gyrofrequencies exceed collision frequencies. Cool threads—fibrils
  and spicules perhaps—grow slowly in thickness as a neutral, ionizing
  front expands across the magnetic field into coronal plasma. Radiative
  intensities estimated for H Lyα are within an order of magnitude of
  those observed, with no ad hoc parameters; only thermal parameters and
  geometric considerations are needed. I speculate that the subsequent
  dynamics of the diffused material might also explain observed properties
  of trace elements.

---------------------------------------------------------
Title: The Fainting of α Centauri A, Resolved
Authors: Ayres, Thomas R.; Judge, Philip G.; Saar, Steven H.; Schmitt,
   Jürgen H. M. M.
2008ApJ...678L.121A    Altcode:
  Beginning in 2003, XMM-Newton snapshot monitoring of α Centauri (HD
  128620, 128621: G2 V, K1 V) documented a steady fading of the primary's
  X-ray corona, which had all but disappeared by early 2005. The steep
  decline in L<SUB>X</SUB> was at odds with the previous two decades
  of high-energy measurements, which showed only modest variability of
  the Sun-like star. A Chandra LETGS spectrum in 2007 June, however,
  fully resolved the source of the curious X-ray darkening: a depletion
  of plasma above ~2 MK had substantially depressed the line spectrum
  where the XMM-Newton response peaks (λ lesssim 30 Å), even though the
  overall coronal luminosity, dominated by longer wavelength emissions,
  had declined only slightly. This is reminiscent of the Sun's magnetic
  activity cycle, where the 2-3 MK active regions of sunspot maximum
  give way to the spatially pervasive, but cycle-independent, 1 MK
  "quiet corona" at minimum. This emphasizes that any discussion of
  cyclic coronal variability in low-activity stars will depend crucially
  on the energy coverage of the measurements.

---------------------------------------------------------
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: Instruments: HRC
Authors: Kraft, Ralph; Kenter, Almus; Ayres, Thomas R.; Judge, Philip
   G.; Saar, Steven H.; Schmitt, Jurgen H. M. M.; Anderson, Gemma;
   Gaensler, Bryan; Chicago Team
2008ChNew..15...13K    Altcode:
  No abstract at ADS

---------------------------------------------------------
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: 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: Asteroseismic signatures of stellar magnetic activity cycles
Authors: Metcalfe, T. S.; Dziembowski, W. A.; Judge, P. G.; Snow, M.
2007MNRAS.379L..16M    Altcode: 2007MNRAS.tmpL..50M; 2007arXiv0704.1606M
  Observations of stellar activity cycles provide an opportunity to study
  magnetic dynamos under many different physical conditions. Space-based
  asteroseismology missions will soon yield useful constraints on the
  interior conditions that nurture such magnetic cycles, and will be
  sensitive enough to detect shifts in the oscillation frequencies due to
  the magnetic variations. We derive a method for predicting these shifts
  from changes in the MgII activity index by scaling from solar data. We
  demonstrate this technique on the solar-type subgiant β Hyi, using
  archival International Ultraviolet Explorer spectra and two epochs of
  ground-based asteroseismic observations. We find qualitative evidence
  of the expected frequency shifts and predict the optimal timing for
  future asteroseismic observations of this star.

---------------------------------------------------------
Title: The Outer Solar Atmosphere during the Maunder Minimum:
    A Stellar Perspective
Authors: Judge, Philip G.; Saar, Steven H.
2007ApJ...663..643J    Altcode:
  By comparing solar data with data of “flat activity” stars at UV and
  soft X-ray wavelengths, we estimate solar chromospheric, transition
  region, and coronal emission as it might have existed during the
  Maunder minimum (1645-1715), the most recent of several episodes of
  persistently weak sunspot activity. Several flat activity stars from
  the Mount Wilson S-index survey have been observed with the Hubble
  Space Telescope and ROSAT. Drawing on published data, we reassess
  the criteria by which a star may be considered as a Maunder minimum
  candidate. Of our targets, HD 10700 and HD 143761 are the most likely
  such candidates. Solar UV spectra from the SOHO and UARS spacecraft, and
  soft X-ray data from the SNOE spacecraft are compared with the stellar
  UV and X-ray data. The comparison suggests that the radiative output
  of the Maunder minimum chromosphere, transition region, and corona
  were similar to (or at least not much less than) those observed under
  conditions close to current solar minima. In turn, this suggests that
  the emitting structures (which on the Sun at sunspot minimum are small
  scale, &lt;&lt;R<SUB>solar</SUB>), including the magnetic network,
  were also similar. These results have implications for the nature
  of the surface magnetic fields and irradiance during the Maunder and
  other magnetic minima, and for the solar dynamo.

---------------------------------------------------------
Title: Spectral Lines for Polarization Measurements of the Coronal
    Magnetic Field. V. Information Content of Magnetic Dipole Lines
Authors: Judge, P. G.
2007ApJ...662..677J    Altcode:
  Stokes profiles of typical magnetic dipole coronal emission lines
  contain information on the embedded magnetic fields, but the
  interpretation of the lines is subject to ambiguities. The present
  study illuminates the information content of coronal emission line
  measurements that include all four Stokes parameters. The simplest
  case of localized emission along the line of sight, such as that
  from a single bright loop, is scrutinized. Knowledge of the “atomic
  alignment” is central to the diagnosis of magnetic fields beyond
  determining the field's azimuth projected on the plane of the sky. For
  localized emission, a method to determine the atomic alignment is
  presented, combining Stokes I, Q, and U observations and statistical
  equilibrium calculations, related to work by Querfeld. The method
  yields the sign of the alignment under conditions that might exist
  25% of the time, thereby reducing the Van Vleck ambiguity from one of
  90° to 180°. Even then, the magnitude of the alignment is sometimes
  ambiguous. With measurements of Stokes V, unambiguous knowledge of
  the alignment also yields the vector field B with just an ambiguity
  of 180° in the plane of the sky. In other, more general cases,
  neither the sign nor the magnitude of the atomic alignment can be
  uniquely determined. Suggestions are made as to how these more serious
  ambiguities might be ameliorated by assuming continuity of magnetic
  fields underlying the polarization maps, an idea first expressed by
  House in 1972. Some conclusions are offered concerning the relative
  merits of formal inversions, diagnosis of magnetic properties from a
  localized region, tomography using solar rotation, and forward modeling.

---------------------------------------------------------
Title: Observations of the Solar Chromosphere
Authors: Judge, P.
2006ASPC..354..259J    Altcode:
  I summarize observational properties of the solar chromosphere with
  emphasis on some of Bob Stein's continuing interests, with an historical
  slant. Bob's interests always concern basic physical processes, so I
  try to identify some basic facts about the chromosphere from the myriads
  of observations from radio to UV wavelengths. The observations suggest
  a simple demarcation between the “low” chromosphere and “high”
  chromosphere which depends on the local plasma-β. Relatively simple
  properties are exhibited in high-β regions (hydrostatic equilibrium,
  three-minute compressive oscillations), and obviously complex thermal
  properties of the “fine structure” observed for many decades,
  arise in low-β chromospheric regions. The latter appears to share
  properties more in common with the intermingled lower corona, where
  the energetically dominant magnetic structure is arguably simpler
  than the high-β regions. But like the coronal heating problem, the
  thermal structure of the upper chromosphere is far more complex and
  is manifested as fine structure.

---------------------------------------------------------
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: Spectral Lines for Polarization Measurements of the Coronal
    Magnetic Field. IV. Stokes Signals in Current-carrying Fields
Authors: Judge, P. G.; Low, B. C.; Casini, R.
2006ApJ...651.1229J    Altcode:
  We present the first theoretical, forward calculations of the Stokes
  profiles of several magnetic dipole (“M1”) coronal emission lines
  produced in current-carrying magnetic structures. An idealized coronal
  model of Low, Fong, and Fan is used, which describes a spherically
  symmetric, hydrostatic background atmosphere, isothermal at a
  coronal temperature of 1.6×10<SUP>6</SUP> K. Embedded is a global,
  axisymmetric magnetic field that is everywhere potential except
  at a quiescent prominence, consisting of an infinitesimally thin,
  equatorial current sheet whose weight is supported by the outward
  discrete Lorentz force in the sheet. This model contains a physically
  nontrivial, localized magnetic structure, although the atmospheric
  plasma is thermally of the simplest stratification possible. The
  calculated M1 coronal lines show clear and distinct signatures of
  the presence and magnitude of this localized magnetic structure,
  in both linear and circular polarizations, even though the thermal
  structure is almost homogeneous. The morphology of maps of linear
  polarization is particularly sensitive to the existence and strength
  of the current sheets, as field lines wrap around them according to
  the Biot-Savart law, and the linear polarization responds to different
  projections of field line directions onto local radius vectors. Of the
  M1 lines studied, those of Fe XIII (1074.7 nm) and Si X (1430.1 nm)
  are especially promising because of their relatively strong linear
  polarization. These forward calculations provide a basis for optimism
  that emission-line measurements may reveal the presence and nature of
  current systems in the corona, and provide motivation for developing
  instruments capable of routinely measuring polarized light in forbidden
  coronal lines.

---------------------------------------------------------
Title: Observational aspects of sunspot oscillations
Authors: Bogdan, T. J.; Judge, P. G.
2006RSPTA.364..313B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Wavelet Phase Coherence Analysis: Application to a Quiet-Sun
    Magnetic Element
Authors: Bloomfield, D. Shaun; McAteer, R. T. James; Lites, Bruce W.;
   Judge, Philip G.; Mathioudakis, Mihalis; Keenan, Francis P.
2004ApJ...617..623B    Altcode:
  A new application of wavelet analysis is presented that utilizes
  the inherent phase information residing within the complex Morlet
  transform. The technique is applied to a weak solar magnetic network
  region, and the temporal variation of phase difference between TRACE
  1700 Å and SOHO/SUMER C II 1037 Å intensities is shown. We present,
  for the first time in an astrophysical setting, the application of
  wavelet phase coherence, including a comparison between two methods
  of testing real wavelet phase coherence against that of noise. The
  example highlights the advantage of wavelet analysis over more
  classical techniques, such as Fourier analysis, and the effectiveness
  of the former to identify wave packets of similar frequencies but
  with differing phase relations is emphasized. Using cotemporal,
  ground-based Advanced Stokes Polarimeter measurements, changes in the
  observed phase differences are shown to result from alterations in
  the magnetic topology.

---------------------------------------------------------
Title: Evaluation of Seeing-Induced Cross Talk in Tip-Tilt-Corrected
    Solar Polarimetry
Authors: Judge, Philip G.; Elmore, David F.; Lites, Bruce W.; Keller,
   Christoph U.; Rimmele, Thomas
2004ApOpt..43.3817J    Altcode:
  We reanalyze the effects of atmosphere-induced image motions on the
  measurement of solar polarized light using a formalism developed by
  Lites. Our reanalysis is prompted by the advent of adaptive optics (AO)
  systems that reduce image motion and higher-order aberrations, by the
  availability of liquid crystals as modulation devices, and by the need
  to understand how best to design polarimeters for future telescopes
  such as the Advanced Technology Solar Telescope. In this first attempt
  to understand the major issues, we analyze the influence of residual
  image motion (tip-tilt) corrections of operational AO systems on the
  cross talk between Stokes parameters and present results for several
  polarization analysis schemes. Higher-order wave-front corrections are
  left for future research. We also restrict our discussion to the solar
  photosphere, which limits several important parameters of interest,
  using some recent magnetoconvection simulations.

---------------------------------------------------------
Title: A Comparison of the Outer Atmosphere of the “Flat Activity”
    Star τ Ceti (G8 V) with the Sun (G2 V) and α Centauri A (G2 V)
Authors: Judge, Philip G.; Saar, Steven H.; Carlsson, Mats; Ayres,
   Thomas R.
2004ApJ...609..392J    Altcode:
  Driven by the desire to understand the roles of acoustic and
  magnetic mechanisms in heating the outer atmospheres of Sun-like
  stars, we compare solar UV spectra with archival STIS spectra from
  the Hubble Space Telescope of α Cen A (G2 V) and new STIS spectra
  of the extremely inactive dwarf star τ Cet (G8 V, V=3.5). The
  activity of τ Cet shows occasional rotational modulations but no
  long-term cyclic variation. It may be in a phase analogous to the
  solar Maunder minimum. Solar disk center intensities from both the
  HRTS instrument and the SUMER instrument on SOHO were converted to
  Sun-as-a-star fluxes by using center-to-limb data from Dammasch and
  colleagues. The derived solar flux spectrum represents conditions
  near the minimum of the solar magnetic activity cycle. We find that
  the τ Cet line profiles differ systematically from those of the Sun
  and α Cen A. While lines formed in the middle chromospheres appear
  similar, the entire emission from the upper chromosphere to the middle
  transition region of τ Cet has lower flux densities by factors of
  ~2, the line widths are significantly narrower, and, uniquely, the
  transition region lines are not significantly redshifted. The soft
  X-ray surface flux of τ Cet, measured between 0.1 and 2.4 keV, is
  ~9×10<SUP>3</SUP> ergs cm<SUP>-2</SUP> s<SUP>-1</SUP>, several times
  smaller than the median solar value. We also find that the UV spectrum
  of α Cen serves as a proxy for a Sun-as-a-star spectrum when the Sun
  is in an intermediate phase of its activity cycle but that its coronal
  emission may be somewhat smaller. We discuss the implications of these
  results for magnetic fields and heating mechanisms in the stars and
  speculate that τ Cet's UV spectrum might represent the solar spectrum
  during a grand minimum phase.

---------------------------------------------------------
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: On the Formation of Extreme-Ultraviolet Helium Lines in the
Sun: Analysis of SOHO Data
Authors: Judge, Philip G.; Pietarila, Anna
2004ApJ...606.1258J    Altcode:
  The resonance lines of helium in the Sun are several times stronger than
  expected, relative to lines of other ions. To explore the origins of
  this “helium enhancement,” we have studied data from the SUMER, CDS,
  MDI, and EIT instruments on the Solar and Heliospheric Observatory
  (SOHO). Time series data obtained in a quiet region and a coronal
  hole indicate that the spatio-temporal properties of the He I 584
  Å, and He II 304 and 1084 Å lines are qualitatively unlike other
  chromospheric and transition region lines. Helium line intensities
  vary slowly compared to chromospheric oscillations and to transient
  transition region brightenings seen in other lines, yet they vary
  rapidly (both spatially and temporally) compared to the coronal
  radiation. This suggests that photoionization/recombination plays a
  minor excitation role in these lines. The Doppler shift of the 584 Å
  line shows a remarkably clear 4-8 mHz oscillation, with no accompanying
  line intensity oscillation. Transient brightenings are used to show
  that nonradial photon scattering might explain the previously found
  diffuse appearance of the network but cannot account for the reduced
  network/internetwork intensity contrast in the 584 Å line. We propose
  a new enhancement mechanism, based on arguments in a companion paper,
  in which predominantly neutral species such as helium diffuse across
  magnetic field lines into regions of hot coronal plasma, but charged
  ions do not. The enhanced internetwork helium emission may arise
  from the diffusion of helium atoms across the chromospheric canopy;
  the enhanced network emission may have contributions from diffusion
  from spicules. This mechanism may naturally explain why the 584 Å
  line shows Doppler shift, but not intensity, oscillations. Finally,
  if a mechanism such as “velocity redistribution” dominates helium
  emission, spectroheliograms of helium lines will be bright in regions of
  large temperature gradients parallel to the magnetic field. Differences
  between helium and other spectroheliograms may then reveal the relative
  contributions of “classical” and “cool loop” models to the observed
  emission.

---------------------------------------------------------
Title: Solar Physics at Evergreen
Authors: Zita, E. J.; Bogdan, T. J.; Carlsson, M.; Judge, P.; Heller,
   N.; Johnson, M.; Petty, S.
2004APS..NWS.C1005Z    Altcode:
  We have recently established a solar physics research program at
  The Evergreen State College. Famed for its cloudy skies, the Pacific
  Northwest is an ideal location for solar physics research activities
  that do not require local observations. Collaborators from the High
  Altitude Observatory (HAO) at the National Center for Atmospheric
  Research have shared solar data from satellite-borne instruments such
  as TRACE and SUMER. HAO colleagues also share data from computer
  simulations of magneto-hydrodynamics (MHD) in the chromosphere,
  generated by the Institute for Theoretical Astrophysics (ITA) at
  the University of Oslo. Evergreen students and faculty learned to
  analyze data from satellites and simulations, in Boulder and Oslo, and
  established an infrastructure for continuing our analyses in Olympia. We
  are investigating the role of magnetic waves in heating the solar
  atmosphere. Comparing data from satellites and simulations shows that
  acoustic oscillations from the photosphere cannot effectively propagate
  into the chromosphere, but that magnetic waves can carry energy up
  toward the hot, thin corona. We find that acoustic waves can change into
  magnetic waves, especially near the magnetic "canopy," a region where
  the sound speed is comparable to magnetic wave speeds. Understanding
  MHD wave transformations and their role in energy transport can help
  answer outstanding questions about the anomalous heating of the solar
  atmosphere. Ref: Waves in the magnetized solar atmosphere II: Waves
  from localized sources in magnetic flux concentrations. Bogdan et al.,
  2003, ApJ 597

---------------------------------------------------------
Title: On the Formation of the Resonance Lines of Helium in the Sun
Authors: Pietarila, Anna; Judge, Philip G.
2004ApJ...606.1239P    Altcode:
  To investigate the cause of anomalously bright resonance lines of
  helium in the Sun, we have studied the magnitude of the enhancements and
  some proposals made to explain them. Calculations in new semiempirical
  solar models indicate that the resonance lines of helium are enhanced
  by factors of 2-5 for He I and between 2 and 9 for He II, depending on
  the elemental abundances assumed. These enhancements are substantially
  less than earlier work has suggested, with the differences arising
  from radiative transfer not only in helium lines but also in lines of
  less abundant elements. Photon scattering, even with small line center
  optical depths (of order unity or less) throughout the transition
  region, is shown to significantly modify line intensities and their
  center-to-limb variation. This effect has important consequences
  both for our analysis and also for the analysis of solar EUV lines in
  general, including emission measure analyses. We have re-examined some
  proposals to explain the enhancements based on the “ionizing plasma”
  picture. The proposals include explicit heating (the “burst” picture)
  and heating via advection (diffusive and/or flowing models and the
  “velocity redistribution” [VR] proposal). We argue that the original
  VR mechanism must be modified to include kinetic effects for helium
  atoms, which reduce the effects of VR. The VR mechanism also naturally
  predicts helium lines that are blue-shifted relative to lines less
  sensitive to VR, which contradicts observations for the He I 584 Å
  line. Ionizing plasma models also potentially lead to enhancement of
  Δn&gt;=1 transitions (n is the principal quantum number) in other
  atoms and ions. Existing observational evidence for enhanced Δn&gt;=1
  transitions in other ions is weak. We conclude that the ionizing plasma
  scenarios are not the sole cause of the helium enhancement. Instead,
  in a companion paper, we propose that the thermodynamic properties
  of noble gases in the upper chromosphere will lead to enhancement of
  their spectral lines if cross-field diffusion into coronal plasma is
  important. Finally, we show that, surprisingly, multifluid flows of
  the kind computed by Fontenla and colleagues can reproduce observed
  intensities of several lines of C and Si and may contain a resolution
  to the helium enhancement problem.

---------------------------------------------------------
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: Chromospher-corona transition region line emissions
Authors: Fontenla, J.; Judge, P.
2004cosp...35..668F    Altcode: 2004cosp.meet..668F
  We study the effects of diffusion and flows on the transition region
  trace-species emission lines and the radiative losses produced by
  them and compare them with observations. We find that mass flows can
  have dramatic effects on the line emissions through the effect on
  non-local ionization and in this way completely alter the radiative
  losses and the structure of the transition regions. Also, in static
  cases thermal diffusion can have a very significant effect on the
  elemental abundance variation that in turn affects the line emissions
  and radiative losses leading to reduced abundances of trace species at
  temperatures around 10^5 K, and the details this effect is dependent on
  the first-ionization-potential. This is due to the combination of large
  temperature gradient and increased mean free path and is expected to
  occur for all species. However, the mass flows would reduce this effect
  and especially in the case of downflows the thermal diffusion can have
  complex results. Also, species diffusion flows can arise from specific
  boundary conditions and may not be directly related to a simultaneous
  mass flow. We discuss several scenarios that may arise in typical
  dynamic cases that have been observed. We show that the transition
  region emissions have the large fluctuations in space and time, much
  more than the chromospheric emissions, and that the radiated energy
  can be easily explained in terms of the downward energy flow from the
  corona coupled with enthalpy and ionization energy carried by the up
  and down mass flows often observed.

---------------------------------------------------------
Title: Oscillatory Signatures above Quiet Sun Magnetic Elements
Authors: Bloomfield, D. S.; McAteer, R. T. J.; Lites, B. W.; Judge,
   P. G.; Mathioudakis, M.; Keenan, F. P.
2004ESASP.547...51B    Altcode: 2004soho...13...51B
  A new application of wavelet analysis is presented. The data used are
  part of Joint Observing Proposal 72 between SoHO and TRACE, obtained on
  1998 May 16 with accompanying groundbased data taken with the Dunn Solar
  Telescope at Sacramento Peak, New Mexico. A weak magnetic network region
  is studied and the temporal variation of phase difference between TRACE
  1700 Å and SoHO/SUMER C II intensities is shown. The example clearly
  highlights the advantages of wavelet analysis over more classical
  techniques such as Fourier analysis, where the effectiveness of the
  technique to identify wavepackets with differing phase difference
  relations is emphasised.

---------------------------------------------------------
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: On the Origin of the Basal Emission from Stellar Atmospheres:
    Analysis of Solar C II Lines
Authors: Judge, Philip G.; Carlsson, Mats; Stein, Robert F.
2003ApJ...597.1158J    Altcode:
  Combining a variety of data with radiation hydrodynamic simulations,
  we examine the heating of the Sun's internetwork chromosphere
  and the hypothesis that the chromospheric “basal” emission
  arises because of acoustic wave dissipation. We focus on the
  2s2p<SUP>2</SUP><SUP>2</SUP>D-2s<SUP>2</SUP>2p<SUP>2</SUP>P<SUP>o</SUP>
  multiplet of C II near 1335 Å, whose basal level of chromospheric
  emission has been reliably determined for stars and the Sun by
  Schrijver and colleagues. By accounting for center-to-limb variations
  and the different spectral bandpasses of the instruments used, we find
  that Schrijver's C II solar basal intensity substantially exceeds
  stellar values, and that it can be identified with intensities seen
  in typical internetwork regions with the SUMER instrument on the SOHO
  spacecraft. Some time-series data sets of internetwork regions are
  then examined and compared with simulations made specifically for a
  typical observational data set, with vertical velocities at the lower
  boundaries fixed from observations with the MDI instrument on SOHO. The
  simulations can qualitatively account for the observed internetwork UV
  continuum fluctuations seen with SUMER, formed 0.6-0.85 Mm above the
  photosphere. However, they fail to capture almost any property of the
  observed internetwork C II multiplet, which is formed substantially
  higher. The time-averaged simulations can account for between 1/7
  and 1/4 of the C II basal intensities; they predict oscillatory power
  between 5 and 10 mHz, whereas internetwork observations are dominated by
  low-frequency (&lt;2 mHz) power of solar origin. The average simulated
  C II intensities, which have a large contribution from the transition
  region heated by conduction down from a coronal upper boundary,
  fall short even of the smaller stellar basal intensities by a factor
  of &gt;=2. Together with known properties of weak, internetwork
  photospheric magnetic fields, we conclude that the internetwork
  upper chromosphere is probably dominated by magnetic heating. Thus,
  the solar basal (and internetwork) intensities of the C II 1335 Å
  multiplet originate from magnetic, and not acoustic, mechanisms,
  in contradiction to the commonly accepted picture

---------------------------------------------------------
Title: The Sun As A Guide To The Stars
Authors: Judge, P.
2003csss...12..158J    Altcode:
  I review the “Sun as a guide to the stars” with emphasis on solar
  magnetism: its origins and effects. I do not present an in-depth
  review but instead try to highlight the current status of relevant
  solar physics. The first half of the discussion focuses on what we have
  learned about dynamo process on both large (ℓ ≈ R<SUB>sun</SUB>)
  and small (ℓ ≪ R<SUB>sun</SUB>) scales. The second half focuses on
  the observed effects of the emerging magnetic fields, especially the
  problem of atmospheric heating. I make no attempt to be complete in
  referencing, but instead try to point to some key references (mostly
  reviews) as appropriate. Some WWW resources are listed.

---------------------------------------------------------
Title: An Estimate of the Sun's ROSAT-PSPC X-Ray Luminosities Using
    SNOE-SXP Measurements
Authors: Judge, Philip G.; Solomon, Stanley C.; Ayres, Thomas R.
2003ApJ...593..534J    Altcode:
  Using solar soft X-ray irradiance measurements from the SXP instrument
  on the SNOE satellite, we relate the solar surface flux densities and
  their variability to those of stars as measured with the PSPC instrument
  on ROSAT. We translate SNOE-SXP measurements into equivalent ROSAT-PSPC
  counts using model spectra calculated from the CHIANTI package. Using
  the SNOE-SXP measurements has significant advantages over earlier
  studies: the absolute calibration is known to +/-25%, SNOE measures the
  Sun as if it were an unresolved star, it has operated over a significant
  fraction of the solar cycle, and its three wavelength channels overlap
  substantially with that of the ROSAT-PSPC instrument. The predicted
  solar X-ray luminosities and surface flux densities are compared with
  measurements from the ROSAT database. We find that we can estimate
  the luminosity of the Sun as seen in the 0.1-2.4 keV (“RASS”)
  passband of ROSAT-PSPC to within +/-50%, not counting sources of
  systematic uncertainty mentioned in an appendix: the result lies
  between 10<SUP>27.1</SUP> and 10<SUP>27.75</SUP> ergs s<SUP>-1</SUP>
  (measured in the existing data set, only partially covering a full
  solar cycle) and between 10<SUP>26.8</SUP> and 10<SUP>27.9</SUP>
  ergs s<SUP>-1</SUP> (extrapolated to the full activity range of a
  typical solar cycle). The solar luminosities lie close to the median
  behavior found for a volume-limited (d&lt;13 pc) sample of G stars
  studied in 1997 by Schmitt, revealing the Sun to be a normal or
  slightly inactive G dwarf. A factor of 1.5 peak-to-peak variation in
  the RASS passband is predicted due simply to rotational modulations
  (i.e., those filtered to include periods P&lt;81 days). The ratio of
  maximum/minimum RASS luminosities from the magnetic activity cycle
  (filtered to include periods P&gt;81 days) are estimated to be 0.7-0.8
  in log10L<SUB>RASS</SUB>, a ratio of 5 or 6. These variations are much
  smaller than both recent estimates of solar X-ray variability and
  the range of X-ray luminosities seen within Schmitt's sample. It is
  suggested that the reported absence of “solar-like” cyclic emission
  in stellar X-rays might partly arise because the Sun is less variable
  than assumed in some earlier work. Repeated ROSAT observations of
  α Cen A during 1995-1998 show X-ray behavior reminiscent of the Sun
  during activity minimum conditions.

---------------------------------------------------------
Title: Investigating the role of plasma topography on chromospheric
    oscillations observed by TRACE
Authors: McIntosh, S. W.; Fleck, B.; Judge, P. G.
2003A&A...405..769M    Altcode:
  We present the results of an investigation into the interaction of
  the topographic structure of the solar chromospheric plasma with the
  wave modes manifesting themselves in the UV continua formed there. We
  show that there is a distinct correlation between the inferred
  plasma topography, the phase-differences between and suppression of
  oscillations in different levels of the solar atmosphere. We interpret
  these factors as evidence of interaction between the oscillations and
  the extended magnetic “canopy”. This work is based on the analysis of
  joint observations made by the Solar and Heliospheric Observatory (SOHO)
  spacecraft and the Transition Region and Coronal Explorer (TRACE).

---------------------------------------------------------
Title: Towards the Measurement of Coronal Magnetic Fields
Authors: Judge, P. G.
2003ASPC..307..437J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Determination of Hyperfine-Induced Transition Rates from
    Observations of a Planetary Nebula
Authors: Brage, Tomas; Judge, Philip G.; Proffitt, Charles R.
2002PhRvL..89B1101B    Altcode: 2002PhRvL..89.1101B
  Observations of the planetary nebula NGC3918 made with the
  STIS instrument on the Hubble Space Telescope reveal the first
  unambiguous detection of a hyperfine-induced transition 2s2p
  <PRE><SUP>3</SUP></PRE>P<SUP>o</SUP><SUB>0</SUB>→2s<SUP>2</SUP>
  <PRE><SUP>1</SUP></PRE>S<SUB>0</SUB> in the berylliumlike emission line
  spectrum of N IV at 1487.89Å. A nebular model allows us to confirm a
  transition rate of 4×10<SUP>-4</SUP> sec(<SUP>-1</SUP>±33% for this
  line. The measurement represents the first independent confirmation
  of the transition rate of hyperfine-induced lines in low ionization
  stages, and it provides support for the techniques used to compute
  these transitions for the determination of very low densities and
  isotope ratios.

---------------------------------------------------------
Title: Observational and Interpretational Challenges
Authors: Judge, P.
2002ASPC..277...45J    Altcode: 2002sccx.conf...45J
  No abstract at ADS

---------------------------------------------------------
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--&gt;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: Challenges of Measuring Coronal Magnetic Fields
Authors: Judge, P.
2002AAS...200.3406J    Altcode: 2002BAAS...34..691J
  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. I will review techniques
  for making such measurements, in particular those that can be applied
  outside of active regions. Forbidden coronal emission lines 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 of magnetic dipole (M1) character can constrain both the
  line-of-sight field strength, B<SUB>&amp;|slash</SUB>, through the
  longitudinal Zeeman effect seen in Stokes V profiles, and the direction
  of the vector field projected onto the plane-of-the-sky, through the
  analysis of resonance scattering-induced linear polarization seen in
  Stokes Q and U, in the so-called “strong field” regime of the Hanle
  effect. Coupled with additional data and models, accurate polarimetry
  can reveal information on coronal magnetic fields, including current
  systems, unobtainable by other means available now or in the near
  future. I will discuss the current challenges presented by such
  measurements for both for the ATST project and in more general terms.

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Title: Physical consequences of the inclusion of anomalous resistivity
    in the dynamics of 2D magnetic reconnection
Authors: Roussev, I.; Galsgaard, K.; Judge, P. G.
2002A&A...382..639R    Altcode:
  The aim of the present paper is to explore the role of anomalous
  resistivity on the dynamics of magnetic reconnection in a 2D
  environment of relevance to the solar transition region. We adopt an
  ad hoc but explicit form of the anomalous resistivity, motivated by a
  streaming instability, in which the resistivity jumps suddenly as the
  electron drift velocity exceeds some fraction of the mean electron
  thermal speed. Experiments have been conducted to investigate the
  impact of various critical speeds and arbitrary scaling constants
  of the resistivity level on the time-dependent evolution of the
  magnetic reconnection process. The specific threshold value is found
  to influence the dynamics of the reconnection, with higher values
  providing a localised on-off effect of patchy diffusion. For a given
  normalised value of the anomalous resistivity, the amount of Joule
  heating released scales inversely with the threshold value. The total
  energy release is found to be above the lower limit of “quiet”
  Sun nano-flares required to maintain a hot corona. The reconnection
  events discussed here may be important to the energy balance of the
  solar transition region and overlying corona, as already suggested in
  earlier work based on SUMER observations.

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Title: On the Nature of Magnetic Shadows in the Solar Chromosphere
Authors: McIntosh, S. W.; Judge, P. G.
2001ApJ...561..420M    Altcode:
  Recent multi-instrument spacecraft studies of the solar photosphere
  and chromosphere have uncovered a feature-a “magnetic shadow”-not
  previously discussed in the literature. A region of the midchromosphere
  neighboring, but not within, a network magnetic element exhibits
  a suppression of both the mean UV line/continuum intensity and the
  characteristic 3 minute oscillation that is clearly observed elsewhere
  in apparently similar internetwork regions. The clearest cases appear
  to occur rarely, and their properties stand in obvious contrast to the
  well-known “aureoles” of enhanced variability seen surrounding some
  plage regions. It is imperative to understand more clearly the nature
  of the shadow region, not least because the suppressed atmospheric
  heating within it has implications for heating processes elsewhere
  in the chromosphere that are dependent on, or at least related to,
  the 3 minute oscillation. Based on the measured photospheric magnetic
  field, its upward extrapolation, and the appearance of spectral features
  formed above the midchromosphere, we suggest that a shadow occurs when
  magnetic structures, in a relatively weak background field, “close”
  locally within the chromosphere, suppressing the upward propagation
  of magnetoatmospheric waves into the chromosphere.

---------------------------------------------------------
Title: A Study of Chromospheric Oscillations Using the SOHO and
    TRACE Spacecraft
Authors: Judge, Philip G.; Tarbell, Theodore D.; Wilhelm, Klaus
2001ApJ...554..424J    Altcode:
  We analyze line and continuum time-series data of the solar atmosphere,
  with between 10 and 60 s cadence, using the MDI and SUMER instruments
  on the SOHO spacecraft and the UV bandpasses on the TRACE satellite. The
  co-aligned data sets sample spectral features formed from photosphere to
  the middle transition region, spanning five decades in pressure, under
  quiet-Sun and plage conditions. We discuss power, phase difference,
  and coherence spectra, and examine data in the time domain. The
  observed photospheric and chromospheric oscillations are strongly
  coupled for frequencies between 2 and 8 mHz. Phase coherences decrease
  with increasing height, with only occasional periods and locations of
  observable coherence up to heights where transition region emission
  lines are formed. The middle chromosphere (in the SUMER continua)
  oscillates in several megameter (Mm) diameter coherent patches
  with power predominantly in the 5-7 mHz range. The TRACE data,
  formed in the upper photosphere, show smaller patterns superimposed
  on these large-scale oscillations, resulting (at least in part)
  from granulation. At the observed spatial scales, all the observed
  properties point to p-modes, especially the “pseudomodes” just above
  the acoustic cutoff frequency, as the dominant mode of the chromospheric
  dynamics. Smaller scale “acoustic event” drivers, associated
  with granular dynamics, appear to be less important. The predominant
  internetwork chromospheric oscillations arise from regions much larger
  horizontally than vertically. If propagating largely vertically, this
  can naturally explain why the one-dimensional simulations of Carlsson
  &amp; Stein might be more successful than expected. The chromospheric
  response to the p-mode driving is, however, intermittent in space and
  time. Some of the intermittency appears to result from the interaction
  of the upward-propagating waves with magnetic fields. Evidence for this
  includes suppressed intensities and oscillations near quiet-Sun network
  elements (which we dub “magnetic shadows”), absence of oscillations
  in internetwork regions neighboring plage magnetic fields, and a change
  in character of the quiet-Sun internetwork oscillations between the
  119 and 104 nm continua formed at 1 and 1.2 Mm. The latter might be
  caused by canopy fields that form between these heights under typical
  quiet-Sun conditions. A SUMER-only data set reported by Wikstøl et
  al. has a factor of 3 more oscillatory power in the 104 nm continuum
  than the data analyzed here, with stronger coherences extending into
  the solar transition region. Together, these data support the general
  picture that the chromosphere oscillates primarily in response to
  forcing by the p-modes, they are therefore large-scale (several Mm
  across) waves, and they are often strongly influenced by magnetic
  effects (internetwork fields, or the overlying canopy), before the
  oscillations even reach the transition region.

---------------------------------------------------------
Title: An Observational Manifestation of Magnetoatmospheric Waves
    in Internetwork Regions of the Chromosphere and Transition Region
Authors: McIntosh, S. W.; Bogdan, T. J.; Cally, P. S.; Carlsson, M.;
   Hansteen, V. H.; Judge, P. G.; Lites, B. W.; Peter, H.; Rosenthal,
   C. S.; Tarbell, T. D.
2001ApJ...548L.237M    Altcode:
  We discuss an observational signature of magnetoatmospheric waves in
  the chromosphere and transition region away from network magnetic
  fields. We demonstrate that when the observed quantity, line or
  continuum emission, is formed under high-β conditions, where β is
  the ratio of the plasma and magnetic pressures, we see fluctuations in
  intensity and line-of-sight (LOS) Doppler velocity consistent with the
  passage of the magnetoatmospheric waves. Conversely, if the observations
  form under low-β conditions, the intensity fluctuation is suppressed,
  but we retain the LOS Doppler velocity fluctuations. We speculate that
  mode conversion in the β~1 region is responsible for this change in
  the observational manifestation of the magnetoatmospheric waves.

---------------------------------------------------------
Title: Towards a Global Picture: Observable Effects Induced by or
    Related to Magnetic Fields
Authors: Judge, P. G.; Charbonneau, P.
2001ASPC..248..659J    Altcode: 2001mfah.conf..659J
  No abstract at ADS

---------------------------------------------------------
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.

---------------------------------------------------------
Title: A Synthesis Code for Forbidden Coronal Lines
Authors: Judge, P. G.; Casini, R.
2001ASPC..236..503J    Altcode: 2001aspt.conf..503J
  No abstract at ADS

---------------------------------------------------------
Title: Spectral Lines for Polarization Measurements of the Coronal
    Magnetic Field. III. Atomic Data for Si IX
Authors: Brage, Tomas; Judge, Philip G.; Jönsson, Per; Edwards, D. P.
2000ApJ...540.1114B    Altcode:
  We report on large-scale ab initio multiconfiguration
  Dirac-Fock (MCDF) calculations for spectral lines
  of Si IX, with emphasis on the forbidden transitions
  2p<SUP>2</SUP> <SUP>3</SUP>P<SUB>J--&gt;J<SUP>'</SUP></SUB>. The
  J=0--&gt;J<SUP>'</SUP>=1 transition at 3.9346 μm holds promise as a
  diagnostic of coronal magnetic fields if and when future coronagraphic
  instruments can measure the polarized light at this wavelength.

---------------------------------------------------------
Title: Erratum: Spectral Lines for Polarization Measurements of the
    Coronal Magnetic Field. II. Consistent Treatment of the Stokes Vector
    for Magnetic-Dipole Transitions
Authors: Casini, R.; Judge, P. G.
2000ApJ...533..574C    Altcode:
  In the paper “Spectral Lines for Polarization Measurements
  of the Coronal Magnetic Field. II. Consistent Treatment of the
  Stokes Vector for Magnetic-Dipole Transitions,” by R. Casini and
  P. G. Judge (ApJ, 522, 524 [1999]), several typographical errors
  were introduced during the production process. The corrections
  are as follows: 1. In the second entry of the fourth panel of
  Table 1, sqrt(3)/2 cosϑ should read sqrt(3/2) cosϑ 2. The
  left-hand sides of equations (23a) and (23b) should be as in
  the left-hand sides of equations (22a) and (22b). 3. In equations
  (24c) and (24e), ρ<SUP>K<SUP>'</SUP></SUP><SUB>0</SUB>(αJ) should read
  ρ<SUP>K<SUP>'</SUP></SUP><SUB>0</SUB><SUP>K<SUP>'</SUP></SUP>(α<SUP>'</SUP>J<SUP>'</SUP>)
  4. In equations (24e) and (24f),
  J<SUP>K<SUP>”</SUP></SUP><SUB>0</SUB>(ω<SUB>α<SUP>'</SUP>J,αJ<SUP>'</SUP></SUB>)
  should read
  J<SUP>K<SUP>”</SUP></SUP><SUB>0</SUB>(ω<SUB>α<SUP>'</SUP>J<SUP>'</SUP>,αJ</SUB>)
  5. The very first sentence in the legend of Figure 5 should be
  deleted. The Press sincerely apologizes for these errors. A last
  typographical error, which instead is the complete responsibility of
  the authors, is the absence of a minus sign in front of the right-hand
  sides of equations (43a) and (43b).

---------------------------------------------------------
Title: Chromospheric and Transition Region Internetwork Oscillations:
    A Signature of Upward-propagating Waves
Authors: Wikstøl, Ø.; Hansteen, V. H.; Carlsson, M.; Judge, P. G.
2000ApJ...531.1150W    Altcode:
  We analyze spectral time series obtained on 1997 April 25 with
  the SUMER instrument on SOHO. Line and continuum data near 1037
  Å were acquired at a cadence of 16 s. This spectral region was
  chosen because it contains strong emission lines of C II, formed
  in the upper chromosphere/lower transition region; O VI, formed
  in the upper transition region; and neighboring continuum emission
  formed in the middle chromosphere. The time series reveal oscillatory
  behavior. Subsonic (3-5 km s<SUP>-1</SUP> amplitude) Doppler velocity
  oscillations in the C II and O VI lines, with periods between 120
  and 200 s, are prominent. They are seen as large-scale coherent
  oscillations, typically of 3-7 Mm length scale, occasionally approaching
  15 Mm, visible most clearly in internetwork regions. The Doppler
  velocity oscillations are related to oscillations seen in the continuum
  intensity, which precede upward velocity in C II by 40-60 s. The C II
  Doppler shift precedes the O VI Doppler shift by 3-10 s. Oscillations
  are also present in the line intensities, but the intensity amplitudes
  associated with the oscillations are small. The continuum intensity
  precedes the C II intensity by 30-50 s. Phase difference analysis
  shows that there is a preponderance of upward-propagating waves in the
  upper chromosphere that drive an oscillation in the transition region
  plasma, thus extending the evidence for upward-propagating waves from
  the photosphere up to the base of the corona.

---------------------------------------------------------
Title: On Spectroscopic Filling Factors and the Solar Transition
    Region
Authors: Judge, P. G.
2000ApJ...531..585J    Altcode:
  The concept of spectroscopic filling factors is examined by assuming
  that observable astrophysical plasmas are inhomogeneous and must
  therefore be described using functions ζ(n), the emission measure
  differential in electron density n. Using a formal definition for the
  spectroscopic filling factor (f<SUB>s</SUB>) and simple distribution
  functions, it is shown that (1) f<SUB>s</SUB> differs from the
  geometric filling factor f unless the plasma is truly homogeneous
  [ζ(n)=ζ<SUB>0</SUB>δ(n-n<SUB>0</SUB>)], (2) f<SUB>s</SUB> depends
  on the choice of line pairs for the same ζ(n), (3) f<SUB>s</SUB>
  systematically underestimates f, and (4) f<SUB>s</SUB> departs
  more from f the broader the distribution ζ(n). Implications for
  the particular case of the unresolved solar transition region are
  discussed. A dynamic “classical” transition region model appears
  to satisfy observed properties, including tiny filling factors
  (10<SUP>-5</SUP>-10<SUP>-2</SUP>) as well as filamentary models. This
  work highlights the nonunique interpretation of spectral data in terms
  of unresolved plasma structure.

---------------------------------------------------------
Title: Non-Uniqueness of Atmospheric Modeling
Authors: Judge, Philip G.; McIntosh, Scott W.
1999SoPh..190..331J    Altcode:
  We focus on the deceptively simple question: how can we use the emitted
  photons to extract meaningful information on the transition region and
  corona? Using examples, we conclude that the only safe way to proceed
  is through forward models. In this way, inherent non-uniqueness is
  handled by adding information through explicit physical assumptions
  and restrictions made in the modeling procedure. The alternative,
  `inverse' approaches, including (as a restricted subset) many standard
  '`spectral diagnostic techniques', rely on more subjective choices
  that have, as yet, no clear theoretical support. Emphasis is on the
  solar transition region, but necessarily discussing the corona, and
  with implications for more general problems concerning the use of
  photons to diagnose plasma conditions.

---------------------------------------------------------
Title: Transition Region Oscillations
Authors: Hansteen, V. H.; Wisktol, O.; Carlsson, M.; Judge, P. G.
1999ESASP.446..351H    Altcode: 1999soho....8..351H
  We analyze time series data obtained April 25th 1997 with the SUMER
  instrument on SOHO. Line and continuum data near 1037 were acquired at
  a cadence of 16s. This spectral region was chosen because it contains
  strong emission lines of C II, formed in the upper chromosphere/lower
  transition region, O VI, formed in the upper transition region, as well
  as neighboring continuum emission formed in the middle chromosphere. The
  dataset reveals oscillatory behavior containing valuable information
  on the physical structure of the chromosphere and transition
  region. Prominent in the data are subsonic (3-5 km/s amplitude)
  velocity oscillations with periods between 120 and 200 sec. They
  are seen as large scale coherent oscillations, typically of 3--7 Mm
  length scale but sometimes approaching 15Mm, visible most clearly
  in internetwork regions. The oscillations are present in C II and O
  VI velocities, as well as in the continuum intensity. The continuum
  intensity precedes upward velocity in the C II line by 40-60s and the C
  III velocity precedes the O VI velocity by 3-10s. The oscillations are
  also present in the intensities of the two lines, but the intensity
  amplitudes associated with the oscillations are small. We find that
  the continuum intensity precedes the C II intensity by 30-50s. These
  phase shifts indicate that there are upward propagating waves in the
  upper chromosphere that drive an oscillation in the transition region
  plasma. The oscillations seem to be present in most internetwork areas
  at any time, thus they are the dominant resolvable dynamical feature
  of the internetwork chromosphere and transition region.

---------------------------------------------------------
Title: On the Doppler Shifts of Solar Ultraviolet Emission Lines
Authors: Peter, H.; Judge, P. G.
1999ApJ...522.1148P    Altcode:
  We examine emission-line profiles observed with the Solar Ultraviolet
  Measurement of Emitted Radiation (SUMER) instrument during the roll
  of the SOHO spacecraft on 1997 March 20. SUMER data were acquired in
  selected wavelength bands including lines from the low chromosphere to
  the corona. Our main aim is to determine the center-to-limb behavior
  of emission lines formed in the chromosphere, transition region,
  and corona, especially of the observed Doppler shifts, to try to
  form a consistent picture of the basic kinematic properties of the
  emitting plasmas. To achieve this we combine the roll data with data
  from the full disk discussed elsewhere and fitted Gaussian profiles
  to the cores of the line profiles. The Doppler-shift data at large
  spatial scales (&gt;50") clearly reveal center-to-limb redshift
  behavior consistent with a cosϑ variation in all transition region
  lines. The three “coronal” lines in the data set (of Ne VIII and
  Mg X) reveal center-to-limb behavior consistent with disk-center
  blueshifts, in contradiction to some previous work. The redshift
  to blueshift transition occurs at electron temperatures of about
  5×10<SUP>5</SUP> K. Furthermore, we present evidence for an outflow
  of the fast solar wind from the coronal holes throughout the whole
  transition region. These results confirm and extend earlier work and
  point toward a (re-) measurement of rest wavelengths of lines formed at
  coronal temperatures in the laboratory. Together these results provide
  a firmer observational foundation for the development of classes of
  models to account for the well-known redshifts and point to the need
  to develop models that can also account for the coronal-line blueshifts.

---------------------------------------------------------
Title: Spectral Lines for Polarization Measurements of the Coronal
    Magnetic Field. II. Consistent Treatment of the Stokes Vector
    forMagnetic-Dipole Transitions
Authors: Casini, R.; Judge, P. G.
1999ApJ...522..524C    Altcode:
  We present a compact, self-consistent formulation for the description
  of polarized radiation from magnetic-dipole transitions occurring
  in the magnetized solar corona. This work differs from earlier
  treatments by Sahal-Bréchot and House in the 1970s, in that the
  radiative emission coefficients for the four Stokes parameters, I,
  Q, U, and V, are treated to first order in a Taylor expansion of the
  line profile in terms of the Larmor frequency of the coronal magnetic
  field. In so doing, the influence on the scattered radiation of both
  atomic polarization, induced through anisotropic irradiation, and
  the Zeeman effect is accounted for in a consistent way. It is found
  that the well-known magnetograph formula, relating the V profile to
  the frequency derivative of the I profile, must be corrected in the
  presence of atomic alignment produced by anisotropic irradiation. This
  correction is smallest for lines where collisions and cascades dominate
  over excitation by anisotropic radiation, but it systematically
  increases with height above the solar limb (up to a theoretical
  maximum of 100%, in the collisionless regime and in the limit of
  vanishing longitudinal magnetic field). Although the correction to
  the magnetograph formula must be calculated separately for each line
  as a function of heliocentric distance, it is likely to be small for
  some lines of practical interest, along lines of sight close to the
  solar limb.

---------------------------------------------------------
Title: Probable Detection of a Bright Infrared Coronal Emission Line
    of Si IX near 3.93 Microns
Authors: Kuhn, J. R.; MacQueen, R. M.; Streete, J.; Tansey, G.; Mann,
   I.; Hillebrand, P.; Coulter, R.; Lin, H.; Edmunds, D.; Judge, P.
1999ApJ...521..478K    Altcode:
  We report here the probable detection of an emission line of Si
  IX that was observed from an open C130 aircraft over the Pacific
  Ocean during the 1998 total solar eclipse. Although the IR data
  themselves are inconclusive because of the uncertainty in the precise
  central wavelengths of the narrowband filters during the eclipse,
  the consistency of the measured IR limb excess with simultaneous EUV
  emission measured by SOHO/Coronal Diagnostic Spectrometer and the EUV
  Imager Telescope support our detection claim. This line appears to
  be the brightest IR coronal line yet observed, and its existence may
  significantly improve future prospects for obtaining optical coronal
  magnetic field measurements.

---------------------------------------------------------
Title: TRACE Images of the Solar Chromosphere, Transition Region,
    and Low Corona at High Cadence and High Spatial Resolution
Authors: Tarbell, T. D.; Handy, B. N.; Judge, P. G.
1999AAS...194.7801T    Altcode: 1999BAAS...31..960T
  We present TRACE images and movies showing C IV emission (transition
  region at 80,000 degrees) and UV continuum (temperature minimum
  region) of quiet and active regions. TRACE images using the 1550,
  1600, and 1700 Angstroms filters can be combined to estimate the total
  emission in the C IV 1548 and 1550 lines and the UV continuum. These
  are supplemented in different observations with MDI magnetograms, TRACE
  171 Angstroms images (Fe IX/X and perhaps O VI), and SUMER spectra of
  chromospheric and transition region lines from SOHO JOP 72. In quiet
  sun, bright C IV transients are seen in the vicinity of flux emergence,
  flux cancellation, and less dramatic interactions of small magnetic
  structures. Some of these are accompanied by high-velocity explosive
  events seen in SUMER spectra. The C IV emission can be well-separated
  from the photospheric magnetic footpoints, suggesting that it takes
  place on current sheets higher in the atmosphere separating different
  flux systems. In active regions, both bright and dark fibrils or loops
  are seen in C IV. Many nano/micro/sub flares are seen, some but not
  all of which are associated with emerging flux. The C IV emission of
  "moss" regions, footpoints of hot coronal loops, is contrasted with
  that of similar plage which does not have hot loops above it. This work
  was supported by the NASA contracts and grants for TRACE, MDI, and SOHO.

---------------------------------------------------------
Title: Lines of OIV and SIV in the Goddard High-Resolution
Spectrograph spectrum of RR Tel: constraints on atomic data
Authors: Harper, G. M.; Jordan, C.; Judge, P. G.; Robinson, R. D.;
   Carpenter, K. G.; Brage, T.
1999MNRAS.303L..41H    Altcode:
  High signal-to-noise ratio spectra of RR Tel obtained at medium
  resolution with the Goddard High-Resolution Spectrograph (GHRS) on the
  Hubble Space Telescope (HST) are used to test available atomic data for
  the OIV 2s^22p ^2P-2s2p^2 ^4P multiplet (UV 0.01). The fine-structure
  intervals of the 2s2p^2 ^4P term given by Moore (1983) appear to need
  revision. The flux ratios of lines within multiplet UV (0.01), which
  have a common upper level, depend only on transition probabilities. The
  observed flux ratio of lines from the ^4P_3/2 level differs from that
  predicted by theory, but this difference cannot be attributed to a
  blend with a line of SIV]. At the electron densities in the RR Tel
  nebula, other flux ratios give information on the relative electron
  excitation rates between the ^2P and ^4P fine-structure levels. Using
  the collision strengths calculated by Zhang, Graziani &amp; Pradhan,
  the rate to the ^4P_5/2 level, relative to the rates to the other J
  states, appears to be underestimated by ~ 10 per cent, which is within
  the expected uncertainty of 20 per cent. We also discuss the SIV 3s^23p
  ^2P-3s3p^2 ^4P multiplet.

---------------------------------------------------------
Title: Spectral decomposition by genetic forward modelling
Authors: McIntosh, S. W.; Diver, D. A.; Judge, P. G.; Charbonneau,
   P.; Ireland, J.; Brown, J. C.
1998A&AS..132..145M    Altcode:
  We discuss the analysis of real and simulated line spectra using
  a genetic forward modelling technique. We show that this Genetic
  Algorithm (GA) based technique experiences none of the user bias
  or systematic problems that arise when faced with poorly sampled or
  noisy data. An important feature of this technique is the ease with
  which rigid a priori constraints can be applied to the data. These
  constraints make the GA decomposition much more accurate and stable,
  especially at the limit of instrumental resolution, than decomposition
  algorithms commonly in use.

---------------------------------------------------------
Title: Evidence in Support of the “Nanoflare” Picture of Coronal
    Heating from SUMER Data
Authors: Judge, P. G.; Hansteen, V.; Wikstøl, Ø.; Wilhelm, K.;
   Schühle, U.; Moran, T.
1998ApJ...502..981J    Altcode:
  We study high signal-to-noise profiles of O IV emission lines obtained
  using the SUMER instrument on SOHO. Data for the quiet Sun obtained
  close to the disk center and at the solar limb were acquired. After
  careful data processing in which disk data were analyzed differentially
  against limb data, we find a systematic correlation between a
  density-sensitive emission-line ratio and Doppler shift across the
  same emission-line profiles. While unidentified blended lines cannot be
  completely discounted, the data suggest that the effects of such blends
  are small. Based on theoretical results in an earlier paper, we argue
  that if wave motions are responsible for the observed behavior, then
  the data reveal evidence for compressive waves propagating downward
  from the corona to the chromosphere. This analysis naturally lends
  support to the dominance of the “nanoflare” mechanism for coronal
  heating over other theories that invoke upward wave propagation,
  but other mechanisms capable of generating downward-propagating waves
  cannot be discounted. If, instead, steady flows are the cause of the
  observed behavior, such as return flows from spicules, then they must
  be such that the density is higher in the downflowing plasma. While
  these particular data do not allow us to discriminate between waves
  or steady flows, additional data from SOHO should be able to address
  this problem. This work required and achieved very accurate wavelength
  calibrations (better than 1/5 of a pixel on the detectors), taking
  SUMER close to its observational capabilities. We therefore present
  the elements of the analysis and calibration of SUMER data that may
  be of interest to other users.

---------------------------------------------------------
Title: On Inferring the Properties of Dynamic Plasmas from Their
Emitted Spectra: The Case of the Solar Transition Region
Authors: Wikstøl, Øivind; Judge, P. G.; Hansteen, Viggo
1998ApJ...501..895W    Altcode:
  We reexamine the issue of inferring physical properties of solar
  plasmas using EUV and UV observations. We focus on the question of
  whether one can determine if typical structures seen as bright in
  typical “transition-region” lines are formed in the thermal interface
  between the coronal and chromospheric plasmas. Since 1983, Feldman and
  colleagues have proposed, based upon Skylab and other data, that much
  of the transition-region emission is formed in so-called unresolved
  fine structures (UFS) that are magnetically and thermally disconnected
  from the corona. This has led others to consider theoretical models of
  the transition region that differ from classical models. We examine the
  evidence cited in support of the UFS picture, specifically by relaxing
  the implicit assumption of a static atmospheric structure. Noting
  that observational data alone do not contain the information necessary
  to infer essential properties of the emitting plasmas, we argue that
  additional information must be added through forward calculations using
  physical models. MHD models of coronal flux tubes are then examined
  with explicit assumptions and boundary conditions, not as an attempt to
  “fit” observed data, but in order to study the formation of emission
  lines in dynamically evolving plasmas that are unresolved in space
  and time. We show that incorrect conclusions can be drawn by applying
  reasonable and traditional diagnostic methods to spectral data when
  unresolved dynamic evolution of the emitting plasma is important but
  not accounted for. In the particular case of the transition region,
  we show that the UFS interpretation is not unique, and is likely to
  be incorrect in the presence of unresolved dynamics. Most or all of
  the evidence for UFS is amenable to a different, equally reasonable
  interpretation, in which the transition-region emission is at all times
  formed in the time-varying thermal interface between the corona and the
  chromosphere. This work is likely to be important for a wider range of
  astrophysical plasmas than simply in the solar transition region. At
  stake is our basic ability to correctly diagnose physical conditions
  of plasmas for which heating mechanisms are not yet understood, but
  which are likely to be time dependent.

---------------------------------------------------------
Title: Hyperfine Induced Transitions as Diagnostics of Isotopic
    Composition and Densities of Low-Density Plasmas
Authors: Brage, Tomas; Judge, Philip G.; Aboussaïd, Abdellatif;
   Godefroid, Michel R.; Jönsson, Per; Ynnerman, Anders; Froese Fischer,
   Charlotte; Leckrone, David S.
1998ApJ...500..507B    Altcode:
  The J = 0 --&gt; J' = 0 radiative transitions, usually viewed
  as allowed through two-photon decay, may also be induced by the
  hyperfine (HPF) interaction in atoms or ions having a nonzero
  nuclear spin. We compute new and review existing decay rates for the
  nsnp <SUP>3</SUP>P<SUP>o</SUP><SUB>J</SUB> --&gt; ns<SUP>2</SUP>
  <SUP>1</SUP>S<SUB>J'=0</SUB> transitions in ions of the Be (n =
  2) and Mg (n = 3) isoelectronic sequences. The HPF induced decay
  rates for the J = 0 --&gt; J' = 0 transitions are many orders of
  magnitude larger than those for the competing two-photon processes,
  and when present are typically 1 or 2 orders of magnitude smaller
  than the decay rates of the magnetic quadrupole (J = 2 --&gt; J'
  = 0) transitions for these ions. Several HPF induced transitions
  are potentially of astrophysical interest in ions of C, N, Na, Mg,
  Al, Si, K, Cr, Fe, and Ni. We highlight those cases that may be of
  particular diagnostic value for determining isotopic abundance ratios
  and/or electron densities from UV or EUV emission-line data. We
  present our atomic data in the form of scaling laws so that, given
  the isotopic nuclear spin and magnetic moment, a simple expression
  yields estimates for HPF induced decay rates. We examine some UV and
  EUV solar and nebular data in light of these new results and suggest
  possible applications for future study. We could not find evidence
  for the existence of HPF induced lines in the spectra we examined,
  but we demonstrate that existing data have come close to providing
  interesting upper limits. For the planetary nebula SMC N2, we derive
  an upper limit of 0.1 for <SUP>13</SUP>C/<SUP>12</SUP>C from Goddard
  High-Resolution Spectrograph data obtained by Clegg. It is likely that
  more stringent limits could be obtained using newer data with higher
  sensitivities in a variety of objects.

---------------------------------------------------------
Title: Spectral Lines for Polarization Measurements of the Coronal
    Magnetic Field. I. Theoretical Intensities
Authors: Judge, P. G.
1998ApJ...500.1009J    Altcode:
  Infrared emission lines are potentially sensitive probes of components
  of the coronal vector magnetic field, through the Zeeman effect,
  and on its direction projected onto the plane of the sky, through
  fluorescent polarization of scattered photospheric light. Prompted
  by the advent of sensitive infrared array detectors, existing atomic
  data were reexamined to compile a complete list of coronal lines that
  may yield a detectable Zeeman effect, through careful differential
  measurements of Stokes profiles, at typical coronal field strengths
  of order 10 G. “Average” intensities were computed for a subset of
  promising forbidden coronal lines. A representative coronal density
  structure was used. The distribution of plasma with temperature was,
  at all heights in the corona, assumed to be that described by a standard
  differential emission measure from extreme-ultraviolet observations of
  the solar disk. Effects of excitation by photospheric radiation were
  included, as well as cascades from collisionally excited higher levels
  having the same principal quantum number as the ground levels. The
  largest source of error in the computed intensities lies in the form
  assumed for the emission measure distribution. The assumed density
  and temperature structure is too simple for detailed comparisons
  with observations of a particular coronal structure. Nevertheless,
  existing observed intensities are consistent with the calculations,
  which suggests that the theoretical intensities of (as yet) unobserved
  lines can be used as a basis for further study. The strongest predicted
  lines arise from magnetic dipole transitions within the ground terms
  of the 2s<SUP>m</SUP>2p<SUP>n</SUP> and 3s<SUP>m</SUP>3p<SUP>n</SUP>,
  m = 1, 2, n = 1, ..., 5, configurations. The most promising lines lie
  between 1 and 10 μm, the lower limit being set by the need to detect
  small field strengths. The upper limit is set by the small Einstein
  A-coefficients and the smaller intensities of the exciting photospheric
  light, both of which lead to smaller forbidden line intensities. The
  most promising lines include [Fe XIII] 1.0747, 1.0798 μm [Si X]
  1.43 μm [Si IX] 2.58, 3.93 μm [Mg VIII] 3.03 μm and [Mg VII]
  5.50, 9.03 μm. An aircraft experiment is being prepared to obtain
  targeted portions of the coronal spectrum between 1 and 10 μm during
  the 1998 February 26 eclipse, with the goal of detecting some of these
  promising lines. This work will help toward the planning and development
  of efficient magnetographs, perhaps space-borne, for the routine
  measurement of coronal magnetic fields in the quiet and active Sun.

---------------------------------------------------------
Title: The relation between line ratio and emission measure analyses
Authors: McIntosh, S. W.; Brown, J. C.; Judge, P. G.
1998A&A...333..333M    Altcode:
  Spectroscopic diagnosis of the temperature and density structure of
  hot optically thin plasmas from emission line intensities is usually
  described in two ways. The simplest approach, the `line ratio' method,
  uses an observed ratio of emission line intensities to determine a
  `spectroscopic mean' value of electron temperature &lt; T_e &gt;
  or electron density &lt; n<SUB>e</SUB>&gt;. The mean value is chosen
  to be the theoretical value of T_e or n<SUB>e</SUB> which matches the
  observed value. The line ratio method is stable, leading to well defined
  values of &lt; T_e &gt; or &lt; n_e &gt; for each line pair but, in the
  realistic case of inhomogeneous plasmas, these are hard to interpret
  since each line pair yields different mean parameter values. The more
  general `differential emission measure' (DEM) method recognizes that
  observed plasmas are better described by distributions of temperature
  or density along the line of sight, and poses the problem in inverse
  form. It is well known that the DEM function is the solution to the
  inverse problem, which is a function of T_e, n_e, or both. Derivation of
  DEM functions, while more generally applicable, is unstable to noise
  and errors in spectral and atomic data. The mathematical relation
  between these two approaches has never been precisely defined. In
  this paper we demonstrate the formal equivalence of the approaches,
  and discuss some potentially important applications of methods based
  upon combining the line ratio and DEM approaches.

---------------------------------------------------------
Title: The Structure of the Chromosphere Properties Pertaining to
    Element Fractionation
Authors: Judge, P. G.; Peter, H.
1998SSRv...85..187J    Altcode:
  We review the structure and dynamics of the solar chromosphere with
  emphasis on the quiet Sun and properties that are relevant to element
  fractionation mechanisms. Attention is given to the chromospheric
  magnetic field, its connections to the photosphere, and to the dynamical
  evolution of the chromosphere. While some profound advances have been
  made in the “unmagnetized” chromosphere, our knowledge of the
  magnetically controlled chromosphere, more relevant for the discussion
  of element fractionation, is limited. Given the dynamic nature of the
  chromosphere and the poorly understood magnetic linkage to the corona,
  it is unlikely that we will soon know the detailed processes leading
  to FIP fractionation.

---------------------------------------------------------
Title: On Chromospheric Heating Mechanisms of “Basal Flux” Stars
Authors: Judge, P. G.; Carpenter, K. G.
1998ApJ...494..828J    Altcode:
  Several pieces of evidence have been pieced together over recent years
  to support the notion that the chromospheric emission measured from
  stars with convection zones results in part from the upward propagation
  and dissipation of acoustic waves. One argument, based on a statistical
  analysis of available UV data of such stars across the H-R diagram,
  suggests the presence of an omnipresent “basal” level of chromospheric
  heating, which has been postulated as resulting from nonlinear acoustic
  wave heating. <P />However, with few exceptions, no studies have been
  made that test more directly the intrinsically dynamic nature of this
  shock-heating mechanism. Therefore, in order to search for more direct
  signatures of such upward-propagating shock waves in lines of C II,
  we examined Goddard High-Resolution Spectrograph spectra of several
  evolved stars that have “basal” levels of activity. No evidence is
  found to support the presence of such waves as a dominant component
  of the heating mechanism. Instead, behavior reminiscent of the solar
  transition region is seen, suggesting a magnetic heating mechanism
  for these stars. <P />We conclude that upward-propagating shock waves
  do not dominate the observed radiative losses from chromospheres of
  stars exhibiting typical “basal” behavior, and we suggest that the
  nonmagnetic origin of the basal components of all convective stars
  must be called into question. New solar data from the SUMER instrument
  on SOHO also suggest problems with the acoustic-wave interpretation,
  although further work is warranted. <P />In the course of this work,
  we also found a simple explanation for previously noted discrepancies
  between calculated and observed ratios of C II lines in the spectrum
  of α Ori. <P />Based on observations with the NASA/ESA Hubble Space
  Telescope, which is operated by the Association of Universities for
  Research in Astronomy, Inc., under NASA contract NAS 5-26555.

---------------------------------------------------------
Title: The Structure of the Chromosphere
Authors: Judge, P. G.; Peter, H.
1998sce..conf..187J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: SUMER Observations of the Quiet Solar Atmosphere: The Network
    Chromosphere and Lower Transition Region
Authors: Judge, Philip; Carlsson, Mats; Wilhelm, Klaus
1997ApJ...490L.195J    Altcode:
  We examine spectral properties of the network chromosphere and lower
  transition region from the SUMER instrument on the SOHO spacecraft,
  using time-series data sets discussed in an accompanying Letter by
  Carlsson, Judge, &amp; Wilhelm. The data were obtained early in the
  mission with no tracking of solar features and so cannot generally
  be used to examine intrinsic variations in features on timescales
  in excess of 383 s. Upon examination of the temporal variations and
  some preliminary power spectrum analysis, we find the following:
  (1) Transition region lines show more redshift in network regions
  than in internetwork regions and also a correlation between line
  intensity brightenings and increased redshift. (2) The internetwork
  “Ca II grain” phenomenon is not seen in He I λ584 or in lines
  of Si III and C III. (3) Very rapid changes are seen in the network
  for transition region lines with no obvious correspondence with the
  underlying chromosphere. (4) He I λ584 line profiles show very slow
  time variations. (5) Small-amplitude (2-5 km s<SUP>-1</SUP>) coherent
  oscillations of 5"-10" scale length and ~130 s period are seen in
  Doppler shifts of Si III between regions of bright network elements. (6)
  Essentially all blueshifts or redshifts are substantially less than line
  widths. We conclude that upward-propagating acoustic shock waves do not
  contribute significantly to the heating of the lower transition region,
  and that ionization equilibrium is likely to fail for the interpretation
  of certain emission lines. The spatial coherency of the Si III velocity
  oscillations indicates that the quiet Sun's magnetic field topology
  is more uniform than emission-line intensity data alone might suggest.

---------------------------------------------------------
Title: Differential Emission Measures-Can we do more??
Authors: McIntosh, S. W.; Brown, J. C.; Judge, P. G.
1997BAAS...29.1120M    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: SUMER Observations Confirm the Dynamic Nature of the Quiet
Solar Outer Atmosphere: The Internetwork Chromosphere
Authors: Carlsson, Mats; Judge, P. G.; Wilhelm, K.
1997ApJ...486L..63C    Altcode: 1997astro.ph..6226C
  On 1996 March 12, during the commissioning phase of the SOHO mission, we
  obtained observations of the quiet-Sun with the SUMER instrument. The
  observations were sequences of 15-20 s exposures of ultraviolet
  emission-line profiles and of the neighboring continua. These data
  contain signatures of the dynamics of the solar chromosphere that are
  uniquely useful because of wavelength coverage, moderate signal-to-noise
  ratios, and image stability. <P />We focus on data for the internetwork
  chromosphere. The dominant observed phenomenon is an oscillatory
  behavior that is analogous to the 3 minute oscillations seen in CaII
  lines. The oscillations appear to be coherent over 3"-8" diameter
  areas. At any time they occur over about 50% of the area studied,
  and they appear as large perturbations in the intensities of lines
  and continua. The oscillations are most clearly seen in intensity
  variations in the ultraviolet (λ &gt; 912 Å) continua, and they are
  also seen in the intensities and velocities of chromospheric lines of
  CI, NI, and OI. Intensity brightenings are accompanied by blueshifts
  of typically 5 km s<SUP>-1</SUP>. Phase differences between continuum
  and line intensities also indicate the presence of upward propagating
  waves. The detailed behavior is different between different lines,
  sometimes showing phase lags. The 3 minute intensity oscillations
  are occasionally seen in second spectra (CII λ1335) but never in
  third spectra (CIII and SiIII). Third spectra and HeI λ584 show
  oscillations in velocity that are not simply related to the 3 minute
  oscillations. The continuum intensity variations are consistent with
  recent simulations of chromospheric dynamics (Carlsson and Stein),
  while the line observations indicate that important ingredients are
  missing at higher layers in the simulations. <P />The data show that
  time variations are crucial for our understanding of the chromosphere
  itself and for the spectral features formed there--the quiet-Sun's
  chromosphere is very dynamic and not “quiet.” The implications of
  these data should be considered when planning chromospheric work with
  instruments such as those on SOHO.

---------------------------------------------------------
Title: Signatures of Acoustic and Magnetic Waves in Solar and
    Stellar Coronae
Authors: Wikstøl, Øivind; Judge, Philip G.; Hansteen, Viggo H.
1997ApJ...483..972W    Altcode:
  Time-dependent dynamical calculations of the radiating gas in solar
  coronal flux tubes are used to identify features of UV spectral-line
  profiles that can reveal the direction in which wave energy flows
  through the solar transition region. The profile features survive
  spatial and temporal averaging through nonlinear dependencies of
  line emission coefficients on thermal properties of the plasma
  that are correlated with fluid velocities. This approach can be
  applied to stellar and other unresolved sources, as well as the
  solar atmosphere. It can be regarded as a new angle of attack on the
  long-standing problem of determining coronal heating mechanisms. The
  approach requires low noise data of high spectral resolution. Therefore,
  it can take advantage of some unique properties of the SUMER instrument
  on SOHO. We make specific predictions for SUMER data that, in principle,
  can test whether energy propagates upward or downward in coronal flux
  tubes, thus allowing one to discriminate between competing theories of
  coronal heating. We are acquiring SUMER data in an attempt to do this.

---------------------------------------------------------
Title: Evidence in Support of the “Nanoflare Picture” of Coronal
    Heating from SUMER Data
Authors: Judge, P.; Wikstol, O.; Hansteen, V.
1997SPD....28.0505J    Altcode: 1997BAAS...29..909J
  We study high signal\--to\--noise profiles of O 4 emission lines
  obtained using the SUMER instrument on SoHO. Data for the quiet Sun
  obtained close to disk center and at the solar limb were acquired. After
  careful data processing in which disk data were analyzed differentially
  against limb data, we find a systematic correlation between a
  density sensitive emission line ratio and Doppler shift across the
  same emission line profiles. Based upon theoretical results in an
  earlier paper, we argue that if wave motions are responsible for
  the observed behavior, then the data reveal evidence for compressive
  waves propagating downwards from the corona to the chromosphere. This
  analysis therefore lends support to the dominance of the “nanoflare”
  mechanism for coronal heating (\cite{Parker1988}) over other theories
  that invoke upward wave propagation. If instead steady flows are the
  cause of the observed behavior, such as return flows from spicules,
  then they must be such that the density is higher in the downflowing
  plasma. We present time series data of other transition region lines
  from SoHO that suggest that episodic heating such as may occur through
  nanoflares is a more reasonable picture of heating mechanisms than
  models based upon steady flows.

---------------------------------------------------------
Title: Working Group 1: Non-Stationary Processes
Authors: Judge, P. G.
1997ESASP.404..125J    Altcode: 1997cswn.conf..125J
  No abstract at ADS

---------------------------------------------------------
Title: SUMER Observations Detecting Downward Propagating Waves in
    the Solar Transition Region
Authors: Wiskstøl, Ø.; Judge, P. G.; Hansteen, V.; Wilhelm, K.;
   Schühle, U.; Moran, T.
1997ESASP.404..731W    Altcode: 1997cswn.conf..731W
  No abstract at ADS

---------------------------------------------------------
Title: Observational signatures of nanoflare heated solar stellar
    coronae
Authors: Wikstøl, Ø.; Judge, P. G.; Hansteen, V. H.
1997AdSpR..20.2289W    Altcode:
  Using time-dependent dynamical models of the radiating gas in coronal
  flux tubes, we identify features in UV spectral line profiles
  that can reveal the direction in which energy flows through the
  solar transition region, in observations without temporal or spatial
  resolution. The profile features survive spatial and temporal averaging
  through non-linear dependencies of the line emission coefficients
  on thermal properties of the plasma that are correlated with the
  material velocity. This approach requires only low noise data of high
  spectral resolution and could naturally be applied to stars as well as
  the solar corona. We make predictions for the SUMER instrument that
  can in principle test whether energy propagates upwards or downwards
  in coronal flux tubes, suggesting a new angle of attack on the long
  standing problem of determining coronal heating mechanisms.

---------------------------------------------------------
Title: Fundamental Limitations of Emission-Line Spectra as Diagnostics
    of Plasma Temperature and Density Structure
Authors: Judge, P. G.; Hubeny, Veronika; Brown, John C.
1997ApJ...475..275J    Altcode:
  We discuss the problem of determining plasma structure from optically
  thin emission lines whose emission coefficients and frequency-integrated
  intensities are dependent on temperature T and electron density n. We
  cast the problem into the inverse form discussed by Hubeny &amp; Judge
  (1995). <P />Three properties of the kernels in the integral equations
  lead to fundamental limitations in trying to determine the source
  term μ(T, n), the “emission measure differential in temperature and
  density,” from a set of emission-line intensities. First, the kernels
  are rather weakly dependent on n. Second, they have asymptotically
  identical dependencies on n. The inverse problem is therefore very
  poorly conditioned in the density dimension. Third, the kernels cannot
  (and may never) be calculated with an accuracy better than +/-10%. These
  properties set limits on the accuracy of all solutions, independent of
  the accuracy of observed line intensities. This concurs with earlier
  but less general work by Brown et al. (1991). <P />We try to determine
  solutions for μ(T, n), using specific target sources and numerical
  algorithms. Using realistic uncertainties, calculations indicate that
  meaningful inverse solutions for μ(T, n) cannot be obtained owing to
  the severe propagation of kernel errors, irrespective of the quality of
  observational data. Solutions for the “emission measure differential
  in temperature” ξ(T) = \smallint μ(T, n)dn are more robust against
  instabilities driven by poor conditioning. <P />Since traditional
  “emission-line diagnostic ratios” can only be defined through μ(T,
  n) (or some generalization thereof), our analysis casts doubt on
  the meaning of plasma properties derived from such line ratios, and
  illustrates the severe nonuniqueness of any equivalent “inverse”
  solution. This work may be important for studying a wide variety of
  atomic and ionic emission-line spectra, including work with instruments
  on SOHO and the Hubble Space Telescope.

---------------------------------------------------------
Title: The Ultraviolet Spectrum of a 3B Class Flare Observed with
    SOLSTICE
Authors: Brekke, P.; Rottman, G. J.; Fontenla, J.; Judge, P. G.
1996ApJ...468..418B    Altcode:
  An observation of the ultraviolet spectrum (1200-1800 Å) during the
  impulsive phase of a very extended 3B-X3 class solar flare on 1992
  February 27 was obtained with the Solar-Stellar Irradiance Comparison
  Experiment (SOLSTICE). This observation is combined with ground-based
  Hα, magnetogram, and microwave data as well as hard X-ray measurements
  from the Ulysses spacecraft. This flare shows a dramatic enhancement of
  lines formed in the solar transition region. The irradiance (emitted
  flux density from the entire solar disk) of the resonance lines of
  C iv and Si iv increased by a factor of 12-13 during the impulsive
  phase of the flare. These irradiance enhancements are comparable
  with those measured during stellar flares. By taking into account the
  emitting flare area we infer that the radiance (specific intensity)
  of the flaring plasma was at least a factor of 15,000 brighter than the
  average solar disk radiance just prior to the event. Assuming the flare
  site's initial radiance was that of a typical active region, it then
  must have brightened by a factor of at least 3400. Such enhancement
  far exceeds previous published values (e.g., OSO 8, Skylab, and SMM)
  and indicates that many observations were affected by limited dynamic
  range. Thus, the SOLSTICE observation may be the first measurement of
  the true UV enhancement during the impulsive phase of very bright solar
  flares. <P />The Si III multiplet near 1295 Å also shows remarkable
  enhancement, but other allowed lines of C II, Si III (1206 Å), N V,
  and He II show more moderate enhancements, the weakest being H I Lyα,
  the irradiance of which increases only 6%. Some of the differences
  between the various enhancements are certainly caused by the timing of
  the observations since the scanning spectrometer observed different
  spectral features over periods of 4 minutes. Other differences due
  to line formation processes are being investigated but are consistent
  with density effects in the line emission coefficients. The inferred
  Lyα radiance enhancement is consistent with current post-impulsive
  phase flare models. However, the formation of the C IV and Si IV lines,
  formed during the impulsive phase of the flare, remains unknown. During
  the impulsive phase of the flare the strong transition region lines
  are systematically redshifted by 50 km s<SUP>-1</SUP>.

---------------------------------------------------------
Title: Intercombinations and Allowed Transitions in O IV
Authors: Brage, Tomas; Judge, P. G.; Brekke, P.
1996ApJ...464.1030B    Altcode:
  We report on large-scale ab initio multiconfiguration Hartree-Fock
  calculations for important multiplets including the UV 0.01
  multiplet, 2s<SUP>2</SUP>2p<SUP>2</SUP>P<SUB>J</SUB>-2s2p<SUP>2</SUP>
  <SUP>4</SUP>P<SUB>j'</SUB>, in O IV. The resulting transition
  probabilities should be accurate to ±5%-10% for intersystem lines and
  1% or better for permitted lines. <P />We present new calculations
  of line emission coefficients using these transition probabilities
  and collisional rate coefficients published by Zhang, Graziani, &amp;
  Pradhan in 1994. We readdress the use of these lines as diagnostics
  of electron densities, paying particular attention to uncertainties
  in density determinations. We find (1) the absolute uncertainties in
  derived densities are difficult to assess, but are at least ±40%
  controlled by uncertainties in collision strengths; (2) our new
  calculations bring observed and computed line ratios into better
  agreement (earlier papers yielding systematically different densities
  make the agreement worse); (3) there is additional evidence for strong
  blends in the 1404.8 emission feature, as argued by other authors,
  and/or evidence for inaccurate laboratory wavelengths; and (4) the
  computed branching ratios are in good agreement with observed ratios to
  within observational uncertainties of ±7%. <P />We determine electron
  densities in a variety of solar features from HRTS data from the first
  and second flights of this instrument. The derived electron densities
  vary remarkably little between quiet Sun network and active regions,
  but resonance line intensities vary dramatically, and we discuss reasons
  for this. Finally, we discuss how new high-quality data from the SUMER
  instrument to be flown on Solar and Heliosphereic Observatory (SO HO)
  could be used to address outstanding problems concerning blends and
  heating of the solar transition region.

---------------------------------------------------------
Title: Hyperfine induced transitions as diagnostics of low density
    plasmas and isotopic abundance ratios.
Authors: Brage, T.; Judge, P. G.; Aboussaid, A.; Godefroid, M. R.;
   Jönsson, P.; Leckrone, D. S.
1996BAAS...28..832B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Hyperfine Induced Transitions as Diagnostics of Low Density
    Plasmas and Isotopic Abundance ratios.
Authors: Brage, T.; Judge, P. G.; Aboussaid, A.; Godefroid, M. R.;
   Jonsson, P.; Leckrone, D. S.
1996AAS...188.0705B    Altcode: 1996BAAS...28V.832B
  We propose a new diagnostics of isotope abundance ratios and electron
  densities for low density plasmas, in the form of J = 0 -&gt;
  J(') = 0 radiative transitions. These are usually viewed as being
  allowed only through two-photon decay, but they may also be induced
  by the hyperfine (HPF) interaction in atomic ions. This predicts a
  companion line to the E1] and M2 lines in the UV0.01 multiplet of
  ions isoelectronic to beryllium (e.g. C III, N IV, O V and Fe XXII)
  or magnesium (e.g. Si II, Ca IX, Fe XV and Ni XVII). As an example
  the companion line to the well known lambda lambda 1906.7,1908.7 lines
  in C III will be at 1909.597 Angstroms, but only present in the (13)
  C isotope (which has nuclear spin different from zero). We present
  new and accurate decay rates for the nsnp (3P^o<SUB>J</SUB>) -&gt;
  ns(2) (1S_{J('}=0)) transitions in ions of the Be (n=2) and Mg (n=3)
  isoelectronic sequences. We show that the HPF induced decay rates for
  the J = 0 -&gt; J(') = 0 transitions are many orders of magnitude
  larger than those for the competing two-photon processes and, when
  present, are typically one or two orders of magnitude smaller than
  the decay rates of the magnetic quadrupole ( J = 2-&gt; J(') = 0)
  transitions for these ions. We show that several of these HPF-induced
  transitions are of potential astrophysical interest, in ions of C, N,
  Na, Mg, Al, Si, K, Cr, Fe and Ni. We highlight those cases that may
  be of particular diagnostic value for determining isotopic abundance
  ratios and/or electron densities from UV or EUV emission line data. We
  present our atomic data in the form of scaling laws so that, given the
  isotopic nuclear spin and magnetic moment, a simple expression yields
  estimates for HPF induced decay rates. We examine some UV solar and
  nebular data in the light of these new results and suggest possible
  cases for future study. We could not find evidence for the existence
  of HPF induced lines in the spectra we examined, but we demonstrate
  that existing data have come close to providing interesting upper
  limits. For the planetary nebula SMC N2 we derive an upper limit of
  (13) C/(12) C of 0.1 from GHRS data obtained by Clegg. It is likely
  that more stringent limits could be obtained with newer data with
  higher sensitivities in a variety of objects.

---------------------------------------------------------
Title: Ultraviolet (1200 to 1800 Angstroms) Emission during the
    Impulsive Phase of a Class 3B-X3 Solar Flare Observed with SOLSTICE
Authors: Brekke, P.; Rottman, C. J.; Fontenla, J.; Judge, P. G.
1996mpsa.conf..213B    Altcode: 1996IAUCo.153..213B
  No abstract at ADS

---------------------------------------------------------
Title: The UV "sun as a star" flare spectrum observed with SOLSTICE
Authors: Brekke, P.; Rottman, G. J.; Fontenla, J.; Judge, P. G.
1996ASPC..109..111B    Altcode: 1996csss....9..111B
  No abstract at ADS

---------------------------------------------------------
Title: Atomic calculations inspired by the Hubble Space Telescope:
    intercombination and forbidden lines.
Authors: Fleming, J.; Brage, T.; Harper, G.; Bell, K. L.; Hibbert,
   A.; Judge, P. G.; Leckrone, D. S.
1996BAAS...28.1203F    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On the Failure of Standard Emission Measure Analysis for
    Solar Extreme-Ultraviolet and Ultraviolet Irradiance Spectra
Authors: Judge, P. G.; Woods, T. N.; Brekke, P.; Rottman, G. J.
1995ApJ...455L..85J    Altcode:
  We perform emission measure analysis of new and accurate UV ( lambda
  &gt; 1200 A) and extreme-ultraviolet (EUV) ( lambda &lt;= 1200 A)
  irradiance ("Sun-as-a-star") emission-line spectra of the Sun. Our
  data consist of (1) daily averaged UV irradiances from the SOLSTICE on
  the UARS spacecraft and (2) EUV irradiances obtained on the same date
  from a \frac {1}{4} m spectrograph flown on a sounding rocket. Both
  instruments have a spectral resolution of roughly 1 A. The absolute
  uncertainties in these data are at most +/-15% (+/-2 sigma ), one
  of the highest photometric accuracies yet achieved. We find large,
  highly significant and systematic discrepancies in the emission measure
  analysis of transition region lines which can only be accounted for by
  a breakdown of one or more standard assumptions. All strong lines above
  1000 A, which are from the Li and Na isoelectronic sequences, are too
  strong by factors of between 2.5 and 7 compared with their counterparts
  in the EUV region. Previous studies were tantalizingly close to finding
  these discrepancies, but those data lacked the wavelength coverage and
  relative photometric precision necessary for definitive conclusions. We
  argue that either dynamical effects, inaccurate treatments of atomic
  processes, and/or Lyman continuum absorption are the culprits. However,
  we favor the former explanation. In any event, this study should have
  implications for models of the solar transition region, for observing
  programs with the CDS and SUMER instruments on SOHO, and for analysis of
  UV spectra for stars across the cool half of the H-R diagram. Finally,
  the discrepancy is not seen for the "coronal" Li-like ions.

---------------------------------------------------------
Title: Solution to the Bivariate Integral Inversion Problem: The
    Determination of Emission Measures Differential in Temperature
    and Density
Authors: Hubeny, Veronika; Judge, Philip G.
1995ApJ...448L..61H    Altcode:
  We present a general solution to the inversion problem of determining
  the "source function" f(t, n) from integral equations of the form
  g<SUB>i</SUB> = \int \limits \int \limits K<SUB>i</SUB>(t,n)f(t,n)dt
  dn. The function f(t, n) represents the most information that can be
  extracted from a set of observables {gi} for a source for which the
  kernel functions Ki(t, n), depending on the two independent variables
  t and n, can be calculated a priori. Our specific application is to
  the inversion of the equations for a set of optically thin emission
  line intensities gi with kernel functions Ki(t, n) which depend
  on both the electron density n and the temperature t, a problem
  defined by Jefferies and colleagues in the early 1970s. We determine
  "regularized" solutions [those for which derivatives of f(t, n)
  are minimized to constrain the allowed solutions] for f(t, n) from
  which the usual emission measure differential in temperature xi
  (t) = ∫f(t, n) dn can be obtained. Unlike some recent work, our
  solution is fully two-dimensional and is not restricted to cases
  where functional dependences are assumed to exist between t and n in
  f(t, n). We compare our solutions for the source terms (derived from
  inversions of calculated intensities from input source functions)
  with input source functions, for typical extreme-ultraviolet and UV
  lines formed in the solar transition region. Details, refinements,
  and applications are left to a later paper. This work is likely to
  be relevant to other areas of astrophysics, and can aid in planning
  observations with spacecraft such as the Hubble Space Telescope and
  the upcoming SOHO mission.

---------------------------------------------------------
Title: GHRS Observations of Cool, Low-Gravity Stars. II. Flow
    and Turbulent Velocities in the Outer Atmosphere of gamma Crucis
    (M3.4 III)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Judge, Philip G.
1995ApJ...444..424C    Altcode:
  The Goddard High Resoulution Spectrograph (GHRS) on the Hubble Space
  Telescope (HST) has been used to obtain medium (R = 20,000) and high
  (R = 85,000) resoultion UV spectra of chromosphere emission features
  for the M3.4 III star gamma Cru. Small Science Aperture (SSA) G270M and
  Echelle-B spectra of selected regions in the 2300-2850 A range were
  obtained to determine the kinematics of the chromosphere using lines
  of C2), Fe2, Co2, Si1/2), Ni2, Mn2, and Mg2. Profiles of C2) (UV 0.01)
  lines and fluorescently excited lines of low optical depth indicate
  average turbulent velocities (Doppler FWHM) of 30.2 +/- 1.3 and 28.8 +/-
  1.3 km/s, respectively. The fluorescent emission lines (mean RV = 21.3
  +/- 0.9 km/s) and the wings of the emission components of Fe2 lines
  (mean RV = 22.8 +/- 0.4 km/s) are approximately at rest relative to
  the radial velocity of the star (21 km/s), while the C2) lines show
  a modest inflow (mean RV = 23.1 +/- 0.9 km/s). The more opaque lines
  of Fe2 and Mg2 exhibit complex profiles resulting from line formation
  in an optically thick, extended expanding atmosphere. The emission
  wings of these lines are broadened by multiple scattering, and they are
  centered near the photospheric radial velocity. Closer to line center,
  these strong lines show a strong blueshifted self-absorption feature
  (already seen in IUE data), indicative of formation in an expanding
  chromosphere, and a previously unseen dip in the profiles on the red
  side of line center. The absorption components, when extracted using
  simple Gaussian fits, show strong correlations with the relative
  optical depths of the lines. The derived absorption flow velocities
  converge to the photospheric velocity as one examines spectra features
  formed deeper in the atmosphere. The blueward abosrption velocity
  increases in magnitude from about 7 to 14 km/s with increasing line
  optical depth - the strong absorptions directly map the acceleration
  of the outflowing stellar wind, while the interpretation of the
  weaker redshifted absorptions is more ambiguous, indicating either an
  inflow of material or formation in an extended, spherically expanding
  outflow. The Mg2 and Fe2 profiles, taken together, imply that the wind
  speed decreases between the atmospheric layers where the Mg2 and Fe2
  self-absorption components are formed. Interstellar absorptions are seen
  in the resonance lines of Mg2 (UV 1) and Fe2 (UV1) with zero-volt lower
  levels, at about -3 km/s, consistent with models of the interstellar
  medium in the direction of gamma Cru. Finally, we have detected the Mg2
  'satellite lines' seen in solar spectra obtained above the limb. In
  gamma Cru these lines are probably fluorescently excited by H Ly beta.

---------------------------------------------------------
Title: Transition Probabilities for the UV0.01 Multiplet in N III
Authors: Brage, Tomas; Fischer, Charlotte Froese; Judge, Philip G.
1995ApJ...445..457B    Altcode:
  We report on large-scale ab initio multiconfiguration
  Hartree-Fock calculations for the UV0.01 multiplet,
  2s<SUP>2</SUP>2p<SUP>2</SUP>P<SUB>J</SUB> - 2s2p<SUP>2 4</SUP>P<SUB>J
  prime</SUB>, in N III. The resulting transition probabilities agree
  very well with recent semiempirical calculations, and the lifetimes for
  two of the three upper levels agree with experiments. The deviation for
  the third level is discussed. Comparisons made with the highest quality
  IUE echelle spectra available -- those of RR Tel and V1016 Cyg (both
  photoionized sources with electron densities below 10<SUP>8</SUP>/cu
  cm) -- show that computed branching ratios of lines sharing a common
  upper level are in agreement with observations to within uncertainties
  of +/- 10%. High-quality solar limb data or stellar data from the
  Hubble Space Telescope (HST) could, in principle, be used to determine
  whether the theoretical or measured lifetimes for the discrepant level
  are in error. Unfortunately, stellar data for high-density plasmas
  (N<SUB>e</SUB> greater than 10<SUP>11</SUP>/cu cm are needed) do not
  yet exist, and existing solar data lack the photometric precision to
  address this problem.

---------------------------------------------------------
Title: The Transition Regions of Capella
Authors: Linsky, Jeffrey L.; Wood, Brian E.; Judge, Philip; Brown,
   Alexander; Andrulis, Catherine; Ayres, Thomas R.
1995ApJ...442..381L    Altcode:
  We have used the Goddard High Resolution Spectrometer (GHRS) to observe
  the spectoscopic binary system Capella (G8 III + G1 III). Exposures
  with the G140L, G140M, G160M, G200M, and echelle gratings provide
  emission line profiles with unprecedented signal-to-noise and spectral
  resolving power (lambda/Delta-lambda) up to 92,000. Multi-Gaussin fits
  to the line profiles show that the hotter star contributes 60%-70% of
  the total flux in the chromospheric O I and Mg II resonance lines, but
  about 90% of the flux in the Si III, Si IV, and C IV lines formed in the
  transition region at T less than or = 10<SUP>5</SUP> K. We find clear
  evidence that the emission lines from the hotter star are systemtically
  redshifted relative to the photosphere with Doppler shifts of 5 +/-
  1 km/s for the +9 +/- 3 km/s in the chromospheric Mg II and O I lines,
  respectively, increasing to +24 +/- 5 km/s for the transition region Si
  IV 1393.8A line. The multi-Gaussian fits to permitted transition region
  lines of SI III, Si IV, C IV, and N V indicate the presence of three
  components: moderately broad lines formed in the transition region of
  the hotter star (component H), narrow lines formed in the transition
  region of the cooler star (component C), and very broad lines that we
  think are formed in microflares on the hotter star (component B). The
  He II 1640.4 A feature has an broad profile, which indicates that it
  is formed by collisional excitation primarily from the hotter star,
  and a weak narrow component that we interpret as due to radiative
  recombination on the cooler star. We observed spin-forbidden emission
  lines of C III), O III), Si III), O IV), O V), and S IV) that are
  sensitive to electron density. Fainter members of the O IV) multiplet
  and all of the S IV) lines have never before been seen in any star than
  the Sun. We determine electron densities in the transition regions
  of the Capella stars using lines ratios of O IV) lines and emission
  measure analysis. The emission measures are self-consistent only when
  the fluxes from each emitting component are considered separately. In
  particular, the transition region abundance distributions appear to
  be different on the two stars, and the spin-forbidden lines were not
  detected in the B component. The emission measures for component
  H (the G1 star) are consistent with a constant electron pressure
  (or hydrostatic equilibrium) transition region with P<SUB>e</SUB> =
  10<SUP>15 + 0.1</SUP>/cu cm K and possibly solar 'coronal' abundances.

---------------------------------------------------------
Title: Excitation of O i Lines in the Solar Chromosphere
Authors: Athay, R. Grant; Judge, Philip G.
1995ApJ...438..491A    Altcode:
  Observations of O I lines in the solar spectrum are examined to
  determine whether differences in behavior of lines of the quintet
  and triplet term systems are consistent with collisional excitation
  and/or photoexcitation of both quintets and triplets. Intensities,
  I<SUB>IR</SUB>, in near-infrared emission lines observed above the
  limb at total eclipse decrease exponentially with height h. The
  inverse scale heights (d In I<SUB>IR</SUB>/dh) for the triplet
  lines at 844.6 nm and quintet lines at 777.2 nm are found to be
  in the ration of 1.45. Ultraviolet O I emission-line intensities
  I<SUB>UV</SUB> observed on the solar disk show strong variations, and
  the distributions of triplet (130.4 nm) and quintet line intensities
  about the means are different. Variances in In I<SUB>UV</SUB> are
  found to have a triplet-to-quintet ratio of 1.50, in close agreement
  with the ratio of d In I<SUB>IR</SUB>/dh. It is shown that the simple
  assumption of collisional excitation of quintets and triplets coupled
  with collisional de-excitation of the quintets leads to the correct
  ratios for both the UV variances and d In I<SUB>IR</SUB>/dh. Also,
  under this assumption d In I<SUB>IR</SUB>/dh for the quintet lines
  is predicted to have the same value as d In I/dh at the head of the
  hydrogen Balmer continuum, which, in fact, it does. On the other hand,
  Carlsson &amp; Judge (1993) have shown that collision rates computed
  from the Vernazza, Avrett, &amp; Loeser (1981, hereafter VAL) model
  chromosphere using current estimates of O I collision strengths are
  too low to produce the observed mean intensity in O I 130.4 nm. In
  a similar sense, we find that the predicted intensity of O I 130.4
  nm is much too weak relative to O I 135.6 nm, and that the VAL mean
  models A-F cannot reproduce the observed behavior of these lines,
  even including photoexcitation by H Ly-beta. These difficulties are
  removed by increasing specific electron-atom collision rates. Such
  increases could reflect large errors in atomic cross sections close
  to threshold and/or the inadequacy of the assumptions made by VAL for
  predicting line intensities. The latter alternative a likely factor. We
  conclude that the O I UV lines are very sensitive to inhomogeneities,
  much more than more traditional chromospheric lines (e.g., Mg II k)
  which are formed over similar regions of the chromosphere. Such lines
  could therefore provide valuable diagnostics of departures of the
  chromopsheric plasma from mean models and thereby place constraints
  upon heating mechanisms, once accurate atomic data become available.

---------------------------------------------------------
Title: Consolidation and Verification of EUVE's Lunar Observing
    Program
Authors: Judge, Philip G.
1995euve.prop...32J    Altcode:
  EUVE has been providing valuable spectrometer data of the moon
  for the duration of the EUVE mission. Our primary goal has been to
  provide solar irradiance variability data at a time when such data
  are extremely scarce. This proposal asks for additional measurements
  to consolidate, calibrate and verify our program to date. The proposal
  differs from previous years in that an EUV spectrograph built by co-I
  Woods will fly on the METEOR satellite (launch October 1995) that will
  monitor the solar EUV irradiance on a daily basis. We therefore ask
  for 1 observation a day for 14 days around full moon to accurately
  define the phase function, and for 1 observation a month for 1 year
  to provide needed overlap (and redundancy, in the case of failure)
  with the METEOR experiment. Very short exposures are required (&lt;
  30 min each) for a total of roughly 40 Ksec.

---------------------------------------------------------
Title: GHRS Spectra of alpha Tau
Authors: Carpenter, K.; Robinson, R.; Judge, P.
1994AAS...185.4509C    Altcode: 1994BAAS...26.1380C
  Goddard High Resolution Spectrograph (GHRS) observations of the K5 giant
  alpha Tau were obtained on 8 April 1994. Spectra of approximately 40
  Angstroms-wide regions centered near 1300, 1550, 1660, 1995, 2340, 2760,
  and 2800 Angstroms were obtained through the Small Science Aperture
  (SSA) with medium resolution (R=20,000) gratings. These data provide
  high-precision profiles of a variety of lines formed in the stellar
  chromosphere and transition region, including O I, Fe II, C I, C II],
  Si II], Mg II, and C IV. Self-reversed emission from O I, Fe II,
  and Mg II provide information on the wind flow velocities, with all
  three ions showing both red and blue-shifted absorption components,
  as seen previously in the Fe II emission from the later-type giants
  gamma Cru and mu Gem. The first evidence for hot plasma in the outer
  atmosphere of alpha Tau is seen in the G160M spectrum centered near
  1550 Angstroms@. This spectrum shows very broad, but distinct features
  due to the C IV (UV 1) doublet, as well as a myriad of much narrower
  emissions formed at cooler temperatures, such as (fluorescent) Fe II and
  perhaps Ni II and C I. C I (UV 2) is seen in emission and a comparison
  of its flux with that in C I (UV 32) will allow an estimation of the C
  I chromospheric column density. Multiple observations of the C II] (UV
  0.01) intercombination multiplet were obtained to search for evidence
  of shocks and/or propagating waves. Results of that search will be
  presented. Finally, very high-resolution (R=85,000) echelle spectra
  were obtained of the Mg II resonance doublet near 2800 Angstroms@. These
  emission features show strong interstellar, stellar, and circumstellar
  absorption components at, above, and below the stellar rest velocity.

---------------------------------------------------------
Title: The `HAO spectral diagnostics package' (HAOS-Diaper)
Authors: Judge, P. G.; Meisner, R. W.
1994ESASP.373...67J    Altcode: 1994soho....3...67J
  No abstract at ADS

---------------------------------------------------------
Title: The “Monochromatic Density Diagnostic” Technique: First
    Detection of Multiple Density Components in the Chromosphere of
    alpha Tauri
Authors: Judge, P. G.
1994ApJ...430..351J    Altcode:
  Emission line profiles of the red giant alpha Tau, obtained by Carpenter
  et al. (1991) using the echelle and medium dispersion gratings of
  the Goddard High Resolution Spectrograph are re-examined. Ratios of
  monochromatic flux densities of lines of the C II) 2s<SUP>2</SUP>
  2p(2)P<SUP>0</SUP> goes to 2s2p<SUP>2</SUP> (4)P multiple near 2325 A,
  well-known diagnostics of electron densities in the chromospheres of
  cool evolved stars, change systematically with relative wavelength
  across the line profiles. With the justifiable assumption that these
  lines are optically thin, this implies that the electron density
  varies sytematically across the lines profiles. This is the first
  time that traditional electron density diagostic line ratios have
  been successfully applied to monochromatic line flux densities in
  cool stars. this work clearly demonstrates the power of very high
  signal-to-noise, high-resolution spectra in the UV. The monochromatic
  density diagonstic technique holds promise as a powerful tool for
  studying flows in a variety of astrophysical objects, including the
  Sun. The paper concludes with a compliation of ions from the boron and
  aluminum sequences for which this technique can be expected to produce
  valuable results using astronomical data from the GHRS and solar data
  from instruments on the Solar and Heliospheric Observatory (SOHO).

---------------------------------------------------------
Title: The Transition Regions of Capella
Authors: Linsky, J. L.; Wood, B. E.; Brown, A.; Andrulis, C.; Judge,
   P.; Ayres, T. R.
1994ASPC...64...62L    Altcode: 1994csss....8...62L
  No abstract at ADS

---------------------------------------------------------
Title: GHRS Observations and Analysis of the 0 I and C I Resonance
    Lines in the UV Spectrum of alpha ORI (M2 Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Judge, Philip
   G.; Ebbets, Dennis C.; Brandt, John C.
1994ASPC...64...56C    Altcode: 1994csss....8...56C
  No abstract at ADS

---------------------------------------------------------
Title: Structures in Transition Region Plasma of Active Regions
Authors: Judge, Philip G.; Brekke, Paal
1994ASPC...68..321J    Altcode: 1994sare.conf..321J
  No abstract at ADS

---------------------------------------------------------
Title: Solar Variability, Lunar Spectroscopy , and Earth's Upper
    Atmosphere
Authors: Judge, Philip G.
1994euve.prop...55J    Altcode:
  Solar EUV radiation and its variability is of central importance to the
  earths upper atmosphere. Variability of the earths upper atmosphere
  is a major concern to NASAs satellite missions. This proposal asks
  for continued measurments of solar EUV variability using EUVE to
  observe solar light scattered from the moon. Analysis of EUVE lunar
  data shows unambiguous evidence that we have detected and can quantify
  solar variability. We can therefore enhance our understanding of the
  physics of the upper atmosphere at a time when solar EUV measurements
  are scarce. Our aims include: (i) to understand phase and polarization
  dependences of solar light scattered from the moon, (ii) to better
  quantify variations in solar EUV irradiance, (iii) to re-calibrate
  these data with a rocket--launched EUV payload (already successfully
  achieved, but a re-observation is desirable), and (iv) to use these
  data with simultaneous UV measurements from UARS as inputs to upper
  atmospheric models. Very short exposures (&lt; 30min.) are required. We
  request observations twice a lunar month, and some other observations
  to permit us to take the necessary steps towards converting lunar
  intensity data to absolute solar irradiances. The total requested time
  is roughly 60 Ksec.

---------------------------------------------------------
Title: On the Weakness of C I and O I Resonance Line Emission from
    the Chromosphere of alpha Ori.
Authors: Carpenter, K.; Robinson, R.; Judge, P.; Ebbets, D.; Brandt, J.
1993AAS...183.1504C    Altcode: 1993BAAS...25Q1313C
  The resonance lines from multiplets UV 2 of both O I and C I are
  typically quite strong in emission in the far-UV spectrum of cool
  stars. However, in the prototypical M-supergiant alpha Ori, these lines
  are remarkably weak, although other transitions from the same upper
  energy levels, O I (UV 146) and C I (UV 32), are observed in strong
  emission despite their much weaker intrinsic strengths. Due to the
  presence of many lines from other species in the regions around the UV
  2 multiplets of O I and C I near 1302 Angstroms and 1655 Angstroms, the
  lines of interest suffer severe blending and progress in understanding
  this flux deficiency is difficult based on low resolution IUE and
  GHRS data. We have therefore obtained medium resolution (R=10,000)
  GHRS spectra of alpha Ori of these complex spectral regions, as well
  as the regions around the O I (UV 146) and C I (UV 32) lines near 1640
  Angstroms and 1993 Angstroms, respectively, to resolve the various
  contributors and allow detailed study of this phenomenon. In this
  paper, we present the spectra and discuss the formation of the O I,
  C I, Fe II, and S I lines which they clearly resolve. Semi-empirical
  modeling of the outer atmosphere of alpha Ori and detailed radiative
  transfer calculations are used to study the creation and destruction
  of O I and C I photons.

---------------------------------------------------------
Title: Chromospheric Heating by Acoustic Shocks: A Confrontation of
    GHRS Observations of alpha Tauri (K5 III) with AB Initio Calculations
Authors: Judge, P. G.; Cuntz, M.
1993ApJ...409..776J    Altcode:
  We compare ab initio calculations of semiforbidden C II line profiles
  near 2325 A with recently published observations of the inactive red
  giant Alpha Tau (K5 III) obtained using the GHRS on board the Hubble
  Space Telescope. Our one-dimensional, time-dependent calculations assume
  that the chromosphere is heated by stochastic acoustic shocks generated
  by photospheric convection. We calculate various models using results
  from traditional (mixing length) convection zone calculations as input
  to hydrodynamical models. The semiforbidden C II line profiles and
  ratios provide sensitive diagnostics of chromospheric velocity fields,
  electron densities, and temperatures. We identify major differences
  between observed and computed line profiles which are related to
  basic gas dynamics and which are probably not due to technical
  modeling restrictions. If the GHRS observations are representative
  of chromospheric conditions at all epochs, then one (or more) of
  our model assumptions must be incorrect. Several possibilities are
  examined. We predict time variability of semiforbidden C II lines for
  comparison with observations. Based upon data from the IUE archives,
  we argue that photospheric motions associated with supergranulation
  or global pulsation modes are unimportant in heating the chromosphere
  of Alpha Tau.

---------------------------------------------------------
Title: Solar EUV Variability Measurements From Lunar Observations
    With EUVE
Authors: Judge, P.; et al.
1993AAS...182.4129J    Altcode: 1993BAAS...25..865J
  No abstract at ADS

---------------------------------------------------------
Title: Line Profile Variations in M Giants: Clues to Mass-Loss and
    Chromospheric Heating Mechanisms
Authors: Judge, P. G.; Luttermoser, D. G.; Neff, D. H.; Cuntz, M.;
   Stencel, R. E.
1993AJ....105.1973J    Altcode:
  Analysis is presented of time-series, high dispersion spectra of
  the Mg II, k, Ca II H, and K lines of the semiregular giants Rho Per
  (M4 II-III, periodicity of about 50 days), R Lyr (M5 III, period of
  about 46 days), and g Her (M6 III, period of about 90 days). The fine
  error sensor on the IUE satellite and ground based UBV photometry was
  used to relate line profile variations to photospheric variations. The
  above mentioned stars were selected to study the relative importance
  of convective motions and global stellar pulsations in determining
  the structure of the outer atmospheres. Small amplitude changes, but
  substantial changes in the profiles of Mg II and Ca II lines were
  detected. It is contended that the observed variability is due to
  changes in chromospheric conditions and not variations within the
  circumstellar shell. The picture of a steady state chromosphere,
  which is modulated on long time scales, is corroborated by these
  observations. Localized heating is found in g Her.

---------------------------------------------------------
Title: On i Lines in the Sun and Stars. I. Understanding the
    Resonance Lines
Authors: Carlsson, M.; Judge, P. G.
1993ApJ...402..344C    Altcode:
  The use of O I lines as spectral diagnostics of conditions in the
  chromospheres of the sun and cool stars is addressed, focusing on
  the resonance lines. The important processes influencing these lines
  are identified and an attempt it made to understand the detailed line
  transfer calculations in terms of simpler analytical models. How the
  lines respond to changes in uncertain atomic parameters is illustrated,
  and it is shown how the O I line flux densities depend simply and
  sensitively on the radiative transfer solution for hydrogen. Approximate
  analytical formulas are derived for the O I line flux densities in
  terms of the hydrogen number densities.

---------------------------------------------------------
Title: Solar Variability, Lunar Spectroscopy and Earth's Upper
    Atmosphere
Authors: Judge, Philip G.
1993euve.prop...31J    Altcode:
  Solar EUV radiation and its variability is of central importance to
  the earths upper atmosphere. Variability of the earths upper atmosphere
  is a major concern to NASAs satellite missions. This LARGE PROJECT (2
  year) proposal asks for continued measurments of solar EUV variability
  using EUVE to observe solar light scattered from the moon. Existing
  EUVE data prove that we can enhance ourunderstanding of the physics
  of the upper atmosphere at a time when solar EUV measurements are
  scarce. Our aims include: (i) to understand the phase and polarization
  dependence of solar light scattered from the moon, (ii) to quantify
  variations in solar EUV irradiance, (iii) to calibrate these data
  with a rocket--launched EUV payload, and (iv) to use these data with
  simultaneous UV measurements from UARS as inputs to upper atmospheric
  models. Very short exposures (&lt;30 min) are required. We request TYPE
  2 observations twice a lunar month, and a variety of TYPE 1 observations
  to permit us to take the necessary steps towards converting lunar
  intensity data to absolute solar irradiances.

---------------------------------------------------------
Title: The Search for Acoustically-Driven Mass-Loss in Evolved Stars
Authors: Stencel, R. E.; Brown, A.; Carpenter, K. G.; Cuntz, M.;
   Judge, P.
1992AAS...181.3603S    Altcode: 1992BAAS...24.1175S
  Recent ab-initio calculations of stochastic stellar wind models by
  Cuntz (1992 in Cool Stars VII, ASP Conf. Ser. 26, p.383) have proven
  remarkably robust in predicting observed chromospheric flow patterns
  including possible variabilities with time in selected cool, evolved
  stars. The calculations solve the equations of hydrodynamics using
  the method of characteristics and assume: (i) saw-tooth shock wave
  profiles, and (ii) wave periods were changed stochastically while
  keeping the wave amplitudes constant (see Cuntz 1990 Ap.J. 349,
  p.141). Among the results of fitting chromospheric flow velocities is
  the implication that the permitted range of acoustic wave periods for
  a given star is constrained. We made use of the IUE satellite during
  August and September 1992 to repeatedly observe two stars, the yellow
  giant Aldebaran (K5 III) and the red supergiant, Betelgeuse (M2 Iab),
  in order to sample variations in their atmospheres on timescales of ~
  10(4) to ~ 10(6) seconds, which bracket the predicted mean acoustic wave
  periods for these objects. In particular, we obtained deep exposures
  in order to measure density-sensitive line ratios within the C II]
  intercombination features near 2325A (cf. Lennon et al. 1985 Ap.J. 294,
  p.200) to test the hypothesis that density fluctuations could be
  measured as a consequence of these acoustic waves. The results of
  these observations will be presented and discussed in terms of the
  number and amplitude of acoustic waves contributing to chromospheric
  heating and mass loss from these stars, as well as the wave origins in
  the evolving oscillatory structure of these stellar interiors. We are
  pleased to acknowledge IUE--NASA grant NAG5-2103 for partial support
  of this effort.

---------------------------------------------------------
Title: Fe II Emission Lines. II. Excitation Mechanisms in Cool Stars
Authors: Judge, P. G.; Jordan, C.; Feldman, U.
1992ApJ...384..613J    Altcode:
  Excitation mechanisms are discussed for the 'resonance' transitions
  (between the 3d(6)4s, 3d7, and 3d(6)4p configurations) of Fe II observed
  in emission in the near-UV spectra of cool stars. The analysis is
  based upon: (1) emission measure analysis of previously measured
  lines in IUE spectra of cool giants; (2) discussion of the behavior
  of Fe II lines observed above the solar limb from Skylab spectra; (3)
  approximate radiative-transfer calculations in a 59 level Fe-II model
  atom using mean escape probabilities and a parameterization of optical
  radiation fields; and (4) accurate radiative transfer calculations in
  a smaller atomic model. The solar spectra show unambiguous evidence
  that electron collisions are responsible for most of the Fe-II emission
  observed above the white-light limb. The terms leading to UV multiplets
  3-6, 34-36, and 61-64 are excited by electron excitation of metastable
  quartet terms below about 4 eV, followed by photoexcitation in lines at
  optical wavelengths by photospheric radiation. A 'cool-star' diagnostic
  diagram is constructed showing the regimes in which electron collisions
  and continuum photoexcitation are important in the chromospheres of
  cool stars.

---------------------------------------------------------
Title: The Unusual Ultraviolet Chromospheric Spectrum of the R
    Coronae Borealis Star, V854 Centauri (NSV 6708), at Minimum Light
Authors: Clayton, Geoffrey C.; Whitney, Barbara A.; Stanford, S. A.;
   Drilling, John S.; Judge, P. G.
1992ApJ...384L..19C    Altcode:
  Results are presented of IUE observations of a decline of the recently
  discovered R CrB star, V854 Cen. These observations are of particular
  interest because they include spectra taken at 7 mag below maximum
  light. The 'chromospheric' emission spectra show striking differences
  from UV spectra of other R CrB stars in decline. Strong emission appears
  in several lines not normally seen in R CrB emission-line spectra,
  in particular at semiforbidden C II 2326, Mg I 2852, and C I 2965,
  2967. Spectral evolution similar to that seen in visible spectra of R
  CrB stars is clearly seen in the UV. It is argued that the differences
  between V854 Cen and other R CrB stars are related to known abundance
  differences or to different temperature and density conditions in the
  emission-line regions of the various R CrB stars. The emission may
  also be significantly affected by the presence of dust in or near the
  emitting region.

---------------------------------------------------------
Title: SI II emission line diagnostics.
Authors: Judge, P. G.; Carpenter, K. G.; Harper, G. M.
1991MNRAS.253..123J    Altcode:
  The present study compares ratios of Si II UV emission lines in a
  variety of objects with computations based on recently published
  collisional data of Dufton and Kingston (1991). A high-quality
  spectrum of Alpha Tau (K5 III) obtained by Carpenter et al. (1991) is
  analyzed using the G270M mode of the GHRS on the HST, in addition to
  high-dispersion data from Skylab and IUE. Agreement between observation
  and theory is satisfactory for most lines. A blend with a line of
  Ni II accounts partially for the discrepancies and solves a problem
  with semiforbidden S II emission measures. Disagreement exists between
  certain observed flux ratios and computed values using recent atomic
  data for the intersystem lines. The discrepancy is most significant
  for Alpha Tau. The computed atomic collision strengths within the
  intersystem multiplet itself are argued as a possible cause of the
  discrepancy.

---------------------------------------------------------
Title: Coordinated IUE/HST Observations of the Flare Star AU mic:
    Results from IUE
Authors: Carpenter, K. G.; Maran, S. P.; Brown, A.; Linsky, J. L.;
   Robinson, R. D.; Byrne, P. B.; Judge, P. G.
1991BAAS...23.1383C    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Fe II Emission Lines. I. Chromospheric Spectra of Red Giants
Authors: Judge, P. G.; Jordan, C.
1991ApJS...77...75J    Altcode:
  A 'difference filtering' algorithm developed by Ayers (1979) is used
  to construct high-quality high-dispersion long-wavelength IUE spectra
  of three giant stars. Measurements of all the emission lines seen
  between 2230 and 3100 A are tabulated. The emission spectrum of Fe II is
  discussed in comparison with other lines whose formation mechanisms are
  well understood. Systematic changes in the Fe II spectrum are related
  to the different physical conditions in the three stars, and examples
  are given of line profiles and ratios which can be used to determine
  conditions in the outer atomspheres of giants. It is concluded that
  most of the Fe II emission results from collisional excitation and/or
  absorption of photospheric photons at optical wavelengths, but some
  lines are formed by fluorescence, being photoexcited by other strong
  chromospheric lines. Between 10 and 20 percent of the radiative losses
  of Fe II arise from 10 eV levels radiatively excited by the strong
  chromospheric H Ly-alpha line.

---------------------------------------------------------
Title: Evolution of the Chromospheres and Winds of Low- and
    Intermediate-Mass Giant Stars
Authors: Judge, P. G.; Stencel, R. E.
1991ApJ...371..357J    Altcode:
  Results are presented of an empirical analysis of the global
  thermodynamical requirements of the winds in the outer atmospheres of a
  representative sample of red giant stars of low- and intermediate-mass
  range. Results indicate that the mass-loss rates in these stars are
  not strongly dependent on the actual physical processes driving the
  winds. It is suggested that nonlinear processes act to regulate wind
  energy fluxes. Possible mechanisms responsible for the chromospheric
  heating and the mass loss in the low- and intermediate-mass giant
  stars are discussed.

---------------------------------------------------------
Title: Radio Continuum Observations of a Variety of Cool Stars
Authors: Drake, S. A.; Linsky, J. L.; Judge, P. G.; Elitzur, M.
1991AJ....101..230D    Altcode:
  Radio-continuum observations at 2 and 6 cm are presented for 26
  cool stars (F0 and later), including 10 F-K main-sequence stars and
  16 F-M giant and supergiant stars. The detection of two M giants,
  g Her and R Lyr, is reported for the first time; a redetection of
  the unusual infrared carbon star IRC + 10216 is also reported. Some
  general conclusions are made concerning the radio-emission properties
  of the various types of cool stars observed. For both the detected and
  nondetected stars, constraints are obtained on the ionized component
  of their mass-loss rates.

---------------------------------------------------------
Title: The Mira/Semi-Regular Connection
Authors: Judge, Philip G.
1991iue..prop.3983J    Altcode:
  Substantial mass-loss for stars on the asymptotic giant branch has
  been inferred for Mira stars for some time. Mass-loss mechanisms
  involving the coupled action of stellar pulsations and dust formation
  have been shown to account or the observed mass-loss rates by Bowen and
  colleagues. Mechanisms for stars with substantial massloss, but which
  are not regular pulsators, are not yet identified or understood. An
  important goal of this proposal is to obtain the data needed to identify
  the mass-loss mechanism for the semi-regular stars. The Mg II line
  fluxes are sensitive indicators of non-radiative processes occuring
  in layers of evolved giants where energy and momentum is imparted to
  the wind. We propose to monitor the Mg II line fluxes with the LWP
  camera at low dispersion, for a sample of semi-regular giant stars,
  This sample differs from previously studied stars because the stars
  have far infrared excesses similar to those of Miras. Simultaneous
  ground based photometry will be obtained to help identify the phase
  of tile variation of the Mg II lines. We will compare our findings
  with our earlier similar studies of Miras and with our study of high
  dispersion Mg II line profiles of "non-dusty" semi-regulars obtained
  during the present (twelfth) round of IUE observations. Using the IRAS
  database and other constraints, we will study the relations between
  Mira-like behavior and the semi-regulars, both SRa and SRb types. From
  this study we will learn about the nature of the mass-loss process from
  cool giants, and obtain strong constraints on models of the evolution of
  the circumstellar envelopes, and hence of stellar evolution on the AGB.

---------------------------------------------------------
Title: Feii Emission Line Diagnostics of the Sun and Stars
Authors: Judge, P.
1991ASIC..341..291J    Altcode: 1991sabc.conf..291J
  No abstract at ADS

---------------------------------------------------------
Title: The Mira/Semi-Regular Connection II
Authors: Judge, Philip G.
1991iue..prop.3984J    Altcode:
  We propose to extend the present 1 year program LGMPJ, "the
  Mira/Semi-Regular Connection" for an extra year. The purpose is to
  obtain a better understanding of mass-loss mechanisms by studying
  the behavior of the Mg II h and k line fluxes in a more complete
  sample of pulsating stars. In program LGMPJ, the allotted observing
  time was insufficient to permit more than a preliminary study
  of 3 stars. Important classes of stars of various infrared and
  variability properties have therefore remained unstudied. The Mg
  II line fluxes are sensitive indicators of non-radiative processes
  occuring in layers of giants where energy and momentum is imparted to
  the wind. We will compare our findings with our earlier IUE studies
  of Miras and "non-dusty" semi-regulars. Using the IRAS database and
  other constraints, we will learn about the nature of the mass-loss
  process from cool giants, and obtain strong constraints on models of
  the evolution of the circumstellar envelopes, and hence of stellar
  evolution on the AGB.

---------------------------------------------------------
Title: Stringent Limits on the Ionized Mass Loss from A and F Dwarfs
Authors: Brown, Alexander; Veale, Anthony; Judge, Philip; Bookbinder,
   Jay A.; Hubeny, Ivan
1990ApJ...361..220B    Altcode:
  Following the suggestion of Willson et al. (1987) that A- and
  F-type main-sequence stars might undergo significant mass loss due to
  pulsationally driven winds, upper limits to the ionized mass loss from A
  and F dwarfs have been obtained using VLA observations. These stringent
  upper limits show that the level of ionized mass loss would have at
  most only a small effect on stellar evolution. Radiative-equilibrium
  atmospheric and wind models for early A dwarfs indicate that it is
  highly likely that a wind flowing from such stars would be significantly
  ionized. In addition, late A and early F dwarfs exhibit chromospheric
  emission indicative of significant nonradiative heating. The present
  mass-loss limits are thus representative of the total mass-loss rates
  for these stars. It is concluded that A and F dwarfs are not losing
  sufficient mass to cause A dwarfs to evolve into G dwarfs.

---------------------------------------------------------
Title: On the disappearance of OI in some high-luminosity cool stars
Authors: Carpenter, K. G.; Norman, D.; Robinson, R.;
   Fernandez-Villacanas, J. L.; Jordan, C.; Judge, P.
1990ESASP.310..307C    Altcode: 1990eaia.conf..307C
  No abstract at ADS

---------------------------------------------------------
Title: Fe II Emission Lines: Chromospheric Spectra of Red Giants
Authors: Judge, P. G.; Jordan, C.
1990BAAS...22..848J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On the Interpretation of Chromospheric Emission Lines
Authors: Judge, P. G.
1990ApJ...348..279J    Altcode:
  This paper reexamines the formation of ultraviolet emission lines in
  stellar chromospheres, using detailed radiative transfer calculations
  and relatively simple methods based on approximate line cooling rates,
  including escape probabilities. Approximations for the cooling integrals
  are demonstrated to work well for 'effectively thin' chromospheric
  lines. Two cases are identified, whose behavior can be understood using
  Ayres's (1979) chromospheric scaling laws relating the chromospheric
  structure to stellar properties: those of inactive stars, like cool
  giants, and more active stars like the sun.

---------------------------------------------------------
Title: Radiative Cooling Functions Below 2X10/4K
Authors: Judge, P. G.; Neff, D. H.
1990ASPC....9...57J    Altcode: 1990csss....6...57J
  No abstract at ADS

---------------------------------------------------------
Title: Toward Mapping the Ultraviolet Circumstellar Shells of
    Late-Type Stars
Authors: Stencel, Robert E.; Judge, Philip G.; Carpenter, Kenneth G.
1990ASPC....9..467S    Altcode: 1990csss....6..467S
  Detection of spatially resolved circumstellar matter surrounding
  selected cool stars, using off-source observations made with the
  International Ultraviolet Explorer satellite, is reported. The data
  demonstrate that: (1) the instrumental scattered light profile of
  IUE appears to depend on the ultraviolet color temperature of the
  star observed, and (2) certain red stars show signal in excess of the
  instrumental levels, at spatial offsets of 10 to 20 arc-seconds from
  the star.

---------------------------------------------------------
Title: The Evolution of Chromospheres and Winds of Low and
    Intermediate Mass Giant Stars
Authors: Judge, P. G.; Stencel, R. E.
1990ASPC....9..411J    Altcode: 1990csss....6..411J
  No abstract at ADS

---------------------------------------------------------
Title: Mass Loss Upper Limits for a and F Dwarfs
Authors: Brown, A.; Veale, A.; Judge, P.; Bookbinder, J.; Hubeny, I.
1990ASPC....9..183B    Altcode: 1990csss....6..183B
  The upper limits of the ionized mass losses of A- and F-type main
  sequence stars are obtained with the VLA to investigate the theory that
  pulsationally driven winds contribute to substantial mass loss in the
  stars. The upper limits are found to be at least one order of magnitude
  lower than the mass-loss loci proposed by Willson et al. (1987). Because
  any wind flowing from the stars should be detectable, the notion that
  A dwarfs are evolving into G dwarfs cannot be supported by the amount
  of mass that A and F dwarfs are shown to be losing.

---------------------------------------------------------
Title: How Consistent are Ab-Initio Models of Giant Star Chromospheres
    with Observations
Authors: Cuntz, M.; Judge, P. G.
1990ASPC....9...61C    Altcode: 1990csss....6...61C
  No abstract at ADS

---------------------------------------------------------
Title: Radiative Transfer in ab-initio Chromospheric Models
Authors: Cuntz, M.; Judge, P. G.
1989BAAS...21Q1101C    Altcode: 1989BAAS...21.1101C
  No abstract at ADS

---------------------------------------------------------
Title: Chromospheres of Chemically Peculiar Giant Stars (invited
    Paper)
Authors: Judge, P. G.
1989eprg.proc..303J    Altcode: 1989IAUCo.106..303J
  The chromospheres of evolved stars with peculiar chemical abundances
  are reviewed, emphasizing the dependence of chromospheric properties
  on the evolutionary status of the stars. A sample of intermediate
  mass stars observed in the radio, IR and UV wavelength regions is
  compiled. The chromospheres of MS, S, and C stars are compared with
  one another. The sample is used to study the relationship between
  stellar parameters and chromospheric heating. The results are used to
  construct a scenario for AGB evolution.

---------------------------------------------------------
Title: Cycle-Dependent Studies of Semi-Regular Giant Stars
Authors: Judge, Philip G.
1989iue..prop.3423J    Altcode:
  We propose to monitor the chromospheres and winds of the semi-regular
  giants Rho Per (M4 II-III, P ~ 50 days) and g Her (M6 III, P ~ 90
  days) as a function of their cyclic photospheric variability using
  LWP observations coordinated with ground based spectroscopy and
  photometry. We have recently studied a sample of 42 stars covering
  various phases of evolution on the redand asymptoticgiant branches. We
  have discovered that as a star evolves from a photometrically
  "constant" early M stax to a semi-regular (SRb) stax near spectral
  type M5 III, important changes in the response of the outer atmosphere
  to the photospheric mechanical energy generation occur. The energy
  fluxes are dominated in the early phases by chromospheric heating and
  radiative losses, and by mass loss in the later phases. "Non-variable"
  and semi-regular K and M stars lose mass by a currently unidentified
  process. The present proposal aims to follow the response of the
  chromosphere and wind, via the emission and absorption components in
  the Mg II and Ca II resonance lines, to the underlying photospheric
  variability in SRb-type M stars. In this way we can test whether
  global photospheric variability on a long timescale (&gt;= weeks,
  i.e. &gt; acoustic cutoff period) is responsible for the enhanced
  massloss and dust formation in non-Mira stars later than M5 and
  whether the energy generated by these pulsations is related to the
  (observationally-inferred) chromospheric heating. Previous monitoring
  studies with IUE of SRb stars reveal variability but they have neither
  adequate phase coverage nor the ground-based support required for
  our study. Our study will help to provide a link between the outer
  atmospheres of the "non-variable" and Mira phases of stellar evolution:
  current theory indicates that the Miras (P &gt; 150 days, DeltaV &gt;
  2.5 mag.) lose substantial mass because of the propagation and decay of
  global acoustic shocks, accompanied by dust formation, generated by the
  regular photospheric pulsations. Our recent study and theoretical work
  suggest that similar processes may be occuring in the shorterperiod,
  smaller amplitude SRb stars. The proposed IUE observations will help
  to clarify the relation of stellar winds and chromospheres to the
  variability properties of stars evolving up the giant branches.

---------------------------------------------------------
Title: Direct UV observations of the circumstellar envelope of
    alpha Orionis.
Authors: Stencel, R. E.; Carpenter, K. G.; Pesce, J. E.; Skinner,
   S.; Brown, A.; Judge, P.
1988ESASP.281a.249S    Altcode: 1988uvai....1..249S; 1988IUE88...1..249S
  Observations were made in the IUE LWP camera, low dispersion mode, with
  alpha Ori being offset various distances from the center of the Long
  Wavelength Large Aperture along its major axis. Signal was acquired
  at all offset positions and is comprised of unequal components of
  background/dark counts, telescope-scattered light, and scattered light
  emanating from the extended circumstellar shell. The star is known from
  optical and infrared observations to possess an extended, arc-minute
  sized, shell of cool material. Attempts to observe this shell with the
  IUE are described, although the deconvolution of the stellar signal
  from the telescope scattered light requires further calibration effort.

---------------------------------------------------------
Title: The excitation of SI emission lines in chromospheres of
    late-type giant stars.
Authors: Judge, P. G.
1988MNRAS.231..419J    Altcode:
  Constraints on the structure of the chromospheres of Alpha Boo,
  Alpha Tau, and Beta Gru derived from high-resolution IUE spectra
  are used to investigate the excitation mechanisms of emission lines
  of neutral sulfur, which are prominent in IUE spectra of late-type
  giant and supergiant stars. Observational data for the S I lines
  from other studies are collected and discussed together with data
  for the prototype M supergiant Alpha Ori. The physical conditions
  under which the emission lines are excited are summarized, and the
  atomic processes and models required to interpret the line fluxes are
  addressed. The processes leading to emission in Alpha Tau, Alpha Boo,
  and Beta Gru are identified. The requirements for more accurate atomic
  and spectroscopic data are discussed, and the potential diagnostic
  value of the various emission lines is assessed.

---------------------------------------------------------
Title: Spectroscopy of Cool Stars from IUE Data
Authors: Judge, P. G.
1988IAUS..132..163J    Altcode:
  IUE has revolutionized our knowledge of the outer atmospheres of cool
  stars, largely through the study of spectral lines, and now we possess a
  quite detailed knowledge of stellar chromospheres, transition regions,
  coronae and winds in the cool half of the HR-diagram. The aim of the
  present review is to highlight advances in this field using IUE data
  with high signal-to-noise ratios.

---------------------------------------------------------
Title: A Very Deep SWP Echellogram of Aldebaran
Authors: Judge, Philip G.
1988iue..prop.3335J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Understanding the ultraviolet spectra of cool stars.
Authors: Jordan, C.; Judge, P. G.
1988CoAMP..21...97J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Modelling the outer atmospheres and winds of K giant stars.
Authors: Judge, P. G.
1987IAUS..122..323J    Altcode:
  It is shown how empirically derived constraints affect models of the
  outer atmospheres and winds of K giants, taking α Boo (K2 III) as
  an example. The importance of empirical approaches prior to making
  semi-empirical models is stressed. The reliability of recent wind
  models is assessed.

---------------------------------------------------------
Title: Delta Andromedae (K3III) : an IRAS source with an unusual
    ultraviolet spectrum.
Authors: Judge, P. G.; Jordan, C.; Rowan-Robinson, M.
1987MNRAS.224...93J    Altcode:
  The IRAS survey has revealed anomalous cool infrared emission from
  a number of otherwise apparently normal K stars. IUE spectra of the
  brightest of these stars, Delta And, which is a spectroscopic binary
  and optical standard K3 III star, is obtained. The IUE spectra show the
  unexpected presence of C IV in emission, implying hot material (about
  100,000 K), and evidence for a strong, high-velocity wind. It is argued
  that the unusual ultraviolet spectrum arises solely from the primary
  star and that it is another example of a 'hybrid' K star. The infrared
  excess appears to be caused by a primordial dust shell extending
  from about 1 to 30 arcsec from the primary. One of the companions of
  Delta And lies close to the inner edge of the shell and another one
  (possibly two) lies close to the outer edge, so that interesting
  dynamical interactions between the companions and the dust shell may
  be expected. The dust shell may be analogous to the Oort cometary
  cloud in the Solar System or to a scaled-up version of Saturn's rings.

---------------------------------------------------------
Title: δ Andromedae (K3 III): a hybrid giant in an extended dust
    shell.
Authors: Jordan, C.; Judge, P. G.; Rowan-Robinson, M.
1987IAUS..122..321J    Altcode:
  Spectra of δ And have been obtained with the International Ultraviolet
  Explorer in both the long and short wavelength regions. These spectra
  show several features unusual in a K giant as cool as δ And, in
  particular. The IRAS observations are interpreted in terms of a cool
  (≡100 K) dust cloud surrounding δ And - a spectroscopic binary
  system - and a third component at 1200 A.U.

---------------------------------------------------------
Title: Re-examining the "Corona-Wind Dividing Line" Diagnostics of
    "Non-Coronal" Atmospheres (Invited review)
Authors: Judge, P. G.
1987LNP...291..294J    Altcode: 1987csss....5..294J; 1987LNP87.291..294J
  A review of observations and analyses of the outer atmospheres of
  "non-coronnl" stars is given, with an emphasis on spectroscopic
  diagnostics. These stars, lying to the right of the "corona-wind
  division" in the HR diagram, have no detectable material above
  temperatures of ∼ 2×10<SUP>4</SUP> K, and instead of solar-like
  transition regions and coronae, they possess relatively massive winds
  and expanding "basal-flux" chromospheres. The discussion is restricted
  to "normal", single, red giants, i.e. oxygen-rich stars which have
  not evolved as far as the asymptotic giant branch, and which have not
  yet developed massive, dusty molecular outflows. The methods described
  can in principle be applied to cool star chromospheres in general.

---------------------------------------------------------
Title: High-Dispersion Observations of Alpha Bootis (K1 III) with
    the International Ultraviolet Explorer
Authors: Ayres, T. R.; Judge, P.; Jordan, C.; Brown, A.; Linsky, J. L.
1986ApJ...311..947A    Altcode:
  The authors have obtained very deeply exposed IUE echelle spectrograms
  of the bright, early-K giant Arcturus. They did not detect significant
  flux in the most prominent high-excitation species of a solar-like
  transition zone, C IV λ1548.2. The presence of a weak feature of
  Si III] λ1892.0, and possibly also Si IV λ1393.8, indicates the
  existence of a small amount of plasma at temperatures as hot as
  6×10<SUP>4</SUP>K. Measurements of C II] multiplet UV0.01 near 2325
  Å provide a lower limit of about 5×10<SUP>9</SUP>cm<SUP>-3</SUP> for
  the electron density in the chromospheric layers. C II UV1 (1335 Å)
  emission is very weak. These results confirm that the "coronal" activity
  of the old red giants is considerably diminished from that of even the
  "quietest" of their main-sequence predecessors, stars like the Sun.

---------------------------------------------------------
Title: Constraints on the outer atmospheric structure of late-type
giants stars with IUE : application to alpha Tau (K5III) and beta Gru
    (M5III).
Authors: Judge, P. G.
1986MNRAS.223..239J    Altcode:
  Empirical constaints on the outer atmospheric structures of α Tau and
  β Gru are derived using high resolution spectra from the International
  Ultraviolet Explorer (IUE) satellite, with methods which have been
  described and applied to α Boo (K2III) in an earlier paper. These
  stars have IUE spectra which are typical of giant stars later than ∼K0
  which lie on the 'wind' side of the 'corona/wind division' in the H-R
  diagram. The methods are based on the interpretation of emission-line
  fluxes and profiles, combining emission measures, column density
  measurements from opacity-sensitive line ratios and electron-density
  measurements from C II] line ratios. Many of the conclusions derived
  earlier for α Boo are confirmed for the later type stars considered
  here: radiative processes are vitally important in determining the
  observed spectra because of the low particle densities in red giants. A
  consistent set of constraints is derived only when such processes are
  taken into account. There is no evidence from IUE that the emission
  regions are significantly extended in the sense suggested by previous
  workers. For α Tau the constraints are used to examine the reliability
  of an earlier chromospheric model of Kelch et al. Finally the general
  implications of this work on the outer atmospheres of late-type giant
  stars are discussed.

---------------------------------------------------------
Title: Formation of Emission Lines in the Outer Atmosphere of Arcturus
    (Alpha Boo K2 III)
Authors: Judge, P. G.; Avrett, E. H.; Loeser, R.
1986BAAS...18..982J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The outer atmospheres of late-type giant stars.
Authors: Judge, P. G.
1986ESASP.263..189J    Altcode: 1986niia.conf..189J; 1986NIA86......189J
  Results of recent work with IUE on the structure of the outer
  atmospheres of late-type giant stars are summarized, based on empirical
  constraints derived from emission lines in α Boo (K2 III), α Tau
  (K5 III) and β Gru (M5 III), observed with deep exposures in the
  high resolution mode of IUE. These stars have IUE spectra typical
  of giant stars on the "wind" side of the "corona-wind division" in
  the HR diagram. Particular attention is paid to the structure of the
  emitting regions, including densities, temperatures, inhomogeneities,
  geometric extents and velocity fields. Comparisons are made with
  earlier chromospheric models and with other spectroscopic work, and
  trends with stellar parameters are examined. Finally, the implications
  of this work for modelling the winds of red giants are discussed.

---------------------------------------------------------
Title: Constraints on the outer atmospheric structure of late-type
giant stars with IUE : methods and application to Arcturus (alpha
    Boo K2III).
Authors: Judge, P. G.
1986MNRAS.221..119J    Altcode:
  Methods for empirically analyzing the emission lines formed in the outer
  atmospheres of late-type low-gravity stars are described and applied
  to the K2III star Alpha Boo. The methods are based on electron-density
  measurements, emission-measure analysis, and determination of the
  optical depths of emission lines. The reduction and measurement of
  IUE data of Alpha Boo is described. The important atomic and radiative
  processes which determine the emission-line fluxes of the 'diagnostic'
  emission lines in late-type giant stars are identified, and the effects
  of the scattering of radiation in optically thick lines are examined
  using results from probabilistic radiative transfer theory, and models
  for line excitation are obtained. Empirical constraints on the outer
  atmospheric structure of Alpha Boo are derived using the observed line
  fluxes and widths and the previously described models.

---------------------------------------------------------
Title: Empirical Constraints on the Outer Atmospheres of Late-Type
    Giant Stars with IUE
Authors: Judge, P. G.
1986IrAJ...17..300J    Altcode:
  Useful constraints on the outer atmospheric structure of late-type
  giant stars can be obtained using emission lines observed with the
  IUE satellite if all important processes in the atomic excitation
  calculations are included. Carpenter et al. (1985) did not include
  such effects, and therefore overestimated the geometric extent of
  the emission regions. The Ayres and Linsky (1975) model for Alpha Boo
  satisfies most of the constraints derived below 8000 K, but the model
  has electron densities and linewidths that are a factor of about 2
  smaller than those observed.

---------------------------------------------------------
Title: Ultraviolet Observations of Young Stars in the Chameleon
    1 Association
Authors: Brown, A.; Linsky, J. L.; Walter, F.; Jordan, C.; Judge,
   P.; Gahm, G.; Feigelson, E. D.
1985BAAS...17R.837B    Altcode: 1985BAAS...17..837B
  No abstract at ADS

---------------------------------------------------------
Title: Emission Line Variability of RY Tau, DR Tau and SU Aur
Authors: Brown, A.; Walter, F. M.; Carpenter, K. G.; Jordan, C.;
   Judge, P.
1985BAAS...17..556B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet spectroscopy of late-type giant and supergiant
    stars
Authors: Judge, Philip Gordon
1985PhDT........44J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A progress report on the analysis of long exposure SWP high
    resolution spectra of cool stars.
Authors: Linsky, J. L.; Ayres, T. R.; Brown, A.; Carpenter, K.;
   Jordan, C.; Judge, P.; Gustafsson, B.; Eriksson, K.; Saxner, M.;
   Engvold, O.; Jensen, E.; Moe, O. K.; Simon, T.
1984NASCP2349..445L    Altcode: 1984fiue.rept..445L; 1984IUE84......445L
  The IUE is the first experiment with sufficient sensitivity to obtain
  high resolution spectra (lambda/delta lambda is approximately 10,000)
  of many cool stars in the vitally important 1200 to 2000 A spectral
  region. These data provide qualitatively new information with
  which to understand the properties of and structures in the outer
  atmospheres of these stars. Also, these cool star spectra will be
  extremely useful in planning for the Space Telescope High Resolution
  Spectrograph, which will be 1000 times more sensitive than IUE but will
  be hampered by limited observing time and limited spectral bandwidth
  in each exposure. Very long exposure, high disperson SWP spectra of
  many stars located throughout the cool half of the HR diagram were
  obtained. These 12 to 21 hour exposures were obtained by combining
  NASA and Vilspa shifts so as to obtain the longest possible exposures
  at times of low background. Included are dwarf stars of spectral type
  G0 V to M2 V, G9.5 III to M5 II giants, G2 Ib to M2 Iab supergiants,
  a number of RS CVn-type systems, and Barium stars.

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Title: Precise measurements of radial velocities of emission lines
    in the far-ultraviolet spectra of late-type stars.
Authors: Ayres, T. R.; Engvold, O.; Moe, D. K.; Simon, T.; Jordan,
   C.; Judge, P.; Brown, A.; Linsky, J. L.
1984NASCP2349..468A    Altcode: 1984fiue.rept..468A; 1984IUE84......468A
  The radial velocities of emission lines in deep short wave prime camera
  echelle exposures of several late-type dwarf and giant stars were
  measured. The goal was to search for absolute and differential Doppler
  shifts of emission lines formed at different temperatures in the stellar
  outer atmospheres analogous to the redshifts of C IV lambda 1548 (10
  to the 5th power K) which occur in the solar transition zone. Existing
  images, taken without the precise radial velocity precautions, of five
  dwarf stars, four giant stars, and three supergiants are reanalyzed.

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Title: Ultraviolet Spectroscopy of Cool Stars from IUE (invited Paper)
Authors: Jordan, C.; Judge, P.; Johansson, S.
1984uxsa.coll...51J    Altcode: 1984IAUCo..86...51J; 1984uxsa.conf...51J
  No abstract at ADS

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Title: Radiative processes in cool star chromospheres.
Authors: Jordan, C.; Judge, P.
1984PhST....8...43J    Altcode: 1984PhyS....8...43J
  Observations made with the IUE satellite between 1200 Å and 3000 Å
  have shown that the spectra of giant and supergiant stars later than
  about K0 are dominated by emission from neutral atoms and singly charged
  ions. The cool star spectra show many examples of photo-excitation,
  line-leaking and fluorescent processes, some of which are discussed
  here. There is evidence that the H Ly α and H Ly β lines play an
  important role in the production of emission from O I, S I and Fe
  II. Some lines which remain without satisfactory explanations in both
  the stellar and solar spectra are discussed.