carpenter

explanation blue bibcodes open ADS page with paths to full text

Author name code: carpenter
ADS astronomy entries on 2022-09-14
author:"Carpenter, Kenneth G."

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Title: Transmissive H2O Reconnaissance Sounder, TH2OR — A Compact
Time-Domain Electromagnetic Instrument for Groundwater Detection
Authors: Nunes, D. C.; Grimm, R. E.; Barba, N.; Burgin, M.; Carpenter,
K.; Krieger, S.; Manthena, R.; McGarey, P.
2022LPICo2655.5054N Altcode:
We are developing a planetary low-power, low-mass transient
electromagnetic sounding instrument intended to test the hypothesis
of an extant deep global aquifer at Mars.

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Title: VizieR Online Data Catalog: ASTRAL: abundance analysis of HR
465 (Nielsen+, 2020)
Authors: Nielsen, K. E.; Carpenter, K. G.; Kober, G. V.; Wahlgren,
G. M.
2021yCat..18990166N Altcode:
The ASTRAL: Hot Stars Treasury Program was designed to achieve the
ultimate combination of high spectral resolution and signal-to-noise
over the far- and near-ultraviolet spectrum. The spectrum of HR465
covers the wavelength interval between 1150 and 3047Å and is composed
of 21 coadded and merged individual recordings. The spectral resolution
shortward of 2334Å is R~30000; however, for wavelengths below 1600Å
the spectrum is modeled with a lower value (R~25000) to achieve a
better match to the observation. For wavelengths above 2350Å the
spectral resolution is ~117000. (2 data files).

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Title: After All, Where is the Martian Ground Water? TH2OR Can Help
Authors: Nunes, D. C.; Grimm, R. E.; Barba, N.; Burgin, M.; Carpenter,
K.; Krieger, S.; Manthena, R.; McGarey, P.
2021LPICo2595.8020N Altcode:
The detection of groundwater at Mars continues to be
elusive. Geoelectric analogs offer guidance on using of the transient
electromagnetic method (TEM), implemented as the TH2OR instrument,
to sound for deep groundwater at Mars.

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Title: Exposing the Lyman-alpha Profiles of Low-Mass Stars
Authors: Peacock, Sarah; Barman, Travis Stuart; Carpenter, Kenneth
G.; Hintz, Dominik; Loyd, R. O. Parke; Schneider, Adam; Shkolnik,
Evgenya L.
2021hst..prop16646P Altcode:
Characterizing potentially habitable planets around low mass stars
is a key focus of current and upcoming missions such as JWST and
TESS. This focus stresses the need for a comprehensive understanding
of the radiation environments in which such planets reside. Low-mass
stars are typically much more active than solar type stars and the
proximity of their habitable zones can be one tenth the distance. The
far-ultraviolet (FUV) radiation emitted by these stars has the
potential to alter an orbiting planet's atmospheric photochemistry,
while the extreme-ultraviolet (EUV) radiation can cause the loss
of planetary atmospheres and surface volatiles. Ly-a emission at
1216 A is the dominant radiation source for low mass stars at FUV
wavelengths and is critical for informing stellar atmosphere models
used to predict the EUV spectrum, but directly measuring a low-mass
star's Ly-a emission is almost always impossible because of the
contaminating effects of interstellar hydrogen. Using Gaia DR2,
we have identified a unique sample of six low mass stars for which
a complete and accurate measurement of their Ly-a line profile is
possible due to their very large radial velocities. Stars with very
large radial velocities (&gt;100 km/s) will have their Ly-a emission
Doppler shifted away from contaminating sources allowing for the
rare opportunity to measure intrinsic Ly-a emission. These proposed
observations of this rare sample of stars will triple the number of
stars with Ly-a emission measured in this way and will improve the
accuracy of computed spectra for all low-mass stars across wavelengths
that drive planetary atmospheric evolution.

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Title: A New Look into K-giants' Chromospheres
Authors: Rau, Gioia; Peacock, Sarah; Carpenter, Kenneth G.
2021RNAAS...5...73R Altcode:
We report the preliminary modeling of archival Center for High
Angular Resolution Astronomy (CHARA)/Visible spEctroGraph and
polArimeter interferometric data of a K-giant star using the PHOENIX
atmosphere code. We find that our preparatory model that includes
only the chromospheric contribution closely reproduces the observed
infrared Ca II triplet line profiles of a test star: the K-giant,
β Cet. This preliminary work requires the additional modeling of the
wind contribution to improve the agreement with observations. We plan
to perform a systematic study of K-giants chromospheric emission with
multi-wavelength and multi-technique observations and modeling. Our
plans include extending the modeling work to include the underlying
wind component for a larger set of stars. Stellar Parameters and Images
with a Cophased Array, the second-generation instrument at CHARA,
will be the ideal instrument to perform such observations and reveal
the chromospheric activity of K-giants.

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Title: Adaptable Autonomous Ocean Access Through Erupting Conduits
Authors: Carpenter, K.; Cable, M. L.; Ono, M.; Kornfeld, R. P.
2020AGUFMP044.0015C Altcode:
The EELS architecture is designed to carry the latest instruments. It
is adaptable to traverse ocean world inspired terrain, fluidized media,
enclosed labyrinthian environments and liquids. It is a snake-like
self-propelled endoscope form comprising serially-replicated segments
with encapsulated locomotion and bending. Multiple segments sequentially
reverse rotations to reduce torsion, or replicate rotations to
perform holonomic movements for steering. This is a first of its
kind Archimedes screw propulsion configuration that act as wheels,
tracks, gripping mechanisms, and propelling units under water working
as propellers. These enable a robot to get to a plume and follow the
streamline to its source and proceed into the open water. In the case
of the unconsolidated plume ejected the robot is buoyant and propelled
though the loose media by the threads, even up steep slopes and can
burrow. In an open fracture system, EELS extends across the gap near
the initiation point of a fracture out of the stream line and pushes
the two end screw mechanisms on each side into the walls, driving
into the plume, then descending. In the vent the threads bite the side
walls, reacting the plume jet forces and creating forward movement when
rotated. The robot stays on the edge of the vent pushing on the outer
walls allowing the vent streamline to pass through the middle. Sensor
feedback enables us to perform accurate force/compliance control without
perfect knowledge of the geometry of the environment; hence the robot
can naturally conform its shape to the size of the vent. This is used
to move the drive screws in any direction to maintain a desired outward
force on crack and vent walls, make the screw threads grip the surface,
direct the robot around bends, and to follow the correct branch of a
conduit across wide gaps. This potential concept has never before been
realized. We will report on the latest developments of this concept
and implications for unique ocean world science.

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Title: The Advanced Spectral Library (ASTRAL): Abundance Analysis
of the Chemically Peculiar Star HR 465
Authors: Nielsen, Krister E.; Carpenter, Kenneth G.; Kober, Gladys V.;
Wahlgren, Glenn M.
2020ApJ...899..166N Altcode:
This paper presents the results of the spectrum analysis of the
B-type magnetic chemically peculiar star HR 465. HR 465 shows unusual
abundance patterns that vary with a period of 21.5 yr. Our observations
are recorded at φ = 0.45, 0.68, and 0.85 of the spectroscopic period,
where φ = 0 represents the phase of maximum flux in the photometric
y-band. Synthetic spectra, computed using an LTE atmosphere model,
are fit to high-resolution ultraviolet Hubble Space Telescope (φ
= 0.45) spectra obtained as part of the Advanced Spectral Library
Project: Hot Stars program. The ultraviolet data are supplemented by
high-resolution optical spectra (φ = 0.68 and 0.85) recorded at the
Nordic Optical Telescope with the SOFIN spectrograph. The optical data
are used as a complement to the high line-density ultraviolet spectrum
to derive accurate abundances for elements without spectral lines in
the ultraviolet and to improve the abundance phase coverage for many
atoms/ions. This analysis presents abundance results for more than
70 atoms/ions and confirms parts of the abundance characteristics
previously reported where elements with high mass numbers show
significant abundance enhancements compared with solar values while
some of the lighter elements show abundance deficiencies. In addition,
our measured abundances are consistent with the periodic variability for
chromium and rare-earth elements. Our results are compared with earlier
investigations of this peculiar object to constrain stellar abundance
and diffusion. * Based on observations with the NASA/ESA Hubble Space
Telescope obtained at the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy,
Inc., under NASA contract NAS5-26555.

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Title: The Search for Liquid Water and Modern-Day Habitats in the
Martian Subsurface
Authors: Stamenkovic, V.; Grimm, R. E.; Burgin, M. S.; Barba, N.;
Manthena, R.; Carpenter, K.; Wright, D.; Krieger, S.; Arumugam, D.;
Beauchamp, R.; Wilcox, B.; Edwards, C.
2020LPI....51.1778S Altcode:
We show how transient electromagnetic sounding can be used to search for
liquid groundwater and modern-day habitats in the martian subsurface.

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Title: Stellar Imager (SI) — A UV/Optical Interferometer to Observe
the Universe in High Definition
Authors: Carpenter, K. G.; Karovska, M.; Rau, G.; Schrijver, C.;
SI Team
2020AAS...23530102C Altcode:
The concept for a space based, UV/Optical Interferometer
with over 200x HST's resolution, named "Stellar Imager" (<A
href="http://hires.gsfc.nasa.gov/si/">http://hires.gsfc.nasa.gov/si/</A>),
was developed as part of the NASA Vision Mission studies ("NASA
Space Science Vision Missions" 2008, ed. M. Allen). SI was a
"Landmark/Discovery Mission" in the 2005 Heliophysics Roadmap and a
candidate UV-optical interferometer (UVOI) in the 2006 Astrophysics
Strategic Plan. SI would enable 0.1 milli-arcsec spectral imaging of
stellar surfaces, and many sources in the Universe in general, and open
an enormous new "discovery space" for Astrophysics with its combination
of high angular resolution, dynamic imaging, and spectral energy
resolution. SI's goal is to study the role of magnetism in the Universe
and revolutionize our understanding of: 1) Solar/Stellar Magnetic
Activity and their impact on Space Weather, Planetary Climates, and
Life; 2) Magnetic and Accretion Processes and their roles in the Origin
and Evolution of Structure and in the Transport of Matter throughout
the Universe; 3) the close-in structure of Active Galactic Nuclei;
and 4) Exo-Solar Planet Transits and Disks. Significant technology
development is critical to enabling SI and other future space-based,
sparse aperture telescopes and distributed-spacecraft missions. The
key technology needs include: 1) precision formation flying of many
spacecraft, 2) precision metrology over km-scales, 3) closed-loop
control of many-element, sparse optical arrays, 4) staged-control
systems with very high dynamic ranges (nm to km-scale). We describe
the needed technology development, science goals, and feasibility
of interferometry from space, as well as provide detail performance
parameters and simulations of the data that could be acquired by this
space interferometer.

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Title: Sailing the winds: exploring the mechanisms driving the winds
in carbon-rich AGB Stars
Authors: Rau, G.; Ohnaka, K.; Wittkowski, M.; Carpenter, K.;
Airapetian, V.
2020AAS...23530101R Altcode:
Evolved stars produce molecules and dust in their extended atmospheres,
enriching significantly the interstellar medium. To understand their
mass loss, it is of fundamental importance to investigate the structure
and atmospheric dynamics of these stars. V Oph, a carbon-rich Asymptotic
Giant Branch (AGB) star, shows extended molecular layers, which vary
over a time scales of tens of days. Our study aims at understanding
if these variations can be explained by dust-driven winds triggered
by stellar pulsation alone, or if other mechanisms are operating. We
show our results, presented in a recent ApJ article, using our
multi-technique modeling of existing photometric and interferometric
VLTI/MIDI data using the latest generation DARWIN models for C-rich
AGB stars. Our results include estimates of the values of fundamental
stellar parameters and a comparison with evolutionary tracks. We also
compute an alternative scenario for the mechanism that drive winds,
based on Alfvén waves propagating in V Oph atmosphere. We found that
the latter mechanism could partially contribute to the acceleration
of the stellar winds of this star. Moreover, using period-luminosity
sequences and interferometric modeling, we infer that V Oph could
be reclassified to a semi-regular star. Future studies, such
as observations with the new capabilities of the James Webb Space
Telescope and with the second-generation instrument at the VLTI,
MATISSE, will be discussed.

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Title: AGB star atmospheres modeling as feedback to stellar
evolutionary and galaxy models
Authors: Rau, Gioia; Wittkowski, M.; Chiavassa, A.; Carpenter, K.;
Nielsen, K.; Airapetian, V. S.
2019IAUS..343..491R Altcode:
The chemical enrichment of the Universe is considerably affected by
the contribution of cool evolved stars. We studied the O-rich star
R Peg and the C-rich star V Oph, using respectively the VLTI/GRAVITY
and VLTI/MIDI instruments. We interpret the data using grids of 1-D
and 3-D dynamic model atmospheres.

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Title: The Impact of Dust/Gas Ratios on Chromospheric Activity in
Red Giant and Supergiant Stars
Authors: Carpenter, Kenneth G.; Rau, Gioia
2019IAUS..343..365C Altcode:
Stencel et al. (1986) analyzed IUE spectra of a modest set of cool
stars and found that they continue to produce chromospheres even in
the presence of high dust levels in their outer atmospheres. This
reversed the previous results of Jennings (1973) and Jennings &amp;
Dyck (1972). We describe an on-going extension of these studies to
a sample of stars representing a broader range in dust/gas ratios,
using archival IUE and archival and new HST data on both RGB and AGB
stars. Surface fluxes in emission lines will be analyzed to assess
the chromospheric activity and obscuration by dust in each star, as
those fluxes will follow a different pattern for reduced activity
(temperature/density dependent) vs. dust obscuration (wavelength
dependent). Wind characteristics will be measured by modeling of
wind-reversed chromospheric emission lines.

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Title: Searching for Liquid Water in the Martian Deep with TH2OR
Authors: Burgin, M. S.; Stamenkovic, V.; Grimm, R. E.; Arumugam, D.;
Beauchamp, R.; Barba, N.; Manthena, R.; Wright, D.; Wilcox, B. H.;
Carpenter, K.; Edwards, C. D.
2019AGUFM.P44B..02B Altcode:
The "holy grail" of planet exploration is the quest for life. This
quest has been framed around "follow the (liquid) water", with
the implication that seeking liquid water is tantamount to seeking
habitable environments. For Mars, pure liquid water is generally only
stable in the deep subsurface, at depths of kilometers. Here, we will
describe (i) how we can use transient electromagnetic techniques (TEM)
to sense liquid groundwater in the Martian subsurface and (ii) discuss
the capabilities of the TH2 OR (Transient H2 O Reconnaissance) TEM
instrument, which is currently being developed at JPL - with a targeted
capability to detect liquid groundwater in the Martian subsurface down
to depths of several kilometers while keeping payload mass and power
small. Our TEM approach is different from radar soundings as it is not
sensitive to the dielectric constant but rather to electric conductivity
and allows much deeper penetration down to aquifer depths of ~1-10
km due to the lower frequencies that are being used (~Hz-kHz for EM
versus ~MHz for radar). EM exploits the fact that only slightly-saline
water has an electric conductivity orders-of magnitude greater than
dry rock. On Mars, we expect especially highly-saline waters due to the
much longer residence time of groundwater than on the geologically and
hydrologically much more active Earth. Moreover, as the Martian crust
is expected to be much drier than the Earth's crust, we expect much
greater contrast ratios in electric conductivity between overburden
(crustal part above aquifer) and a putative aquifer on Mars than on the
Earth. These "Martian TEM advantages" allow us to sound with TH2 OR
down to depths of kilometers in order to infer the depth, thickness,
and also salinity of liquid subsurface water. Salinity, especially in
combination with information on local geothermal gradients, can hence
also allow us to indirectly estimate its chemical composition. The
ability to characterize the water chemistry to some degree is a
particularly important feature of TEM sounding, which other methods
generally lack. This opens the possibility to use TH2 OR to detect
and characterize the habitability of deep subsurface environments on
modern-day Mars.

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Title: Exobiology Extant Life Surveyor (EELS)
Authors: Ono, M.; Carpenter, K.; Cable, M. L.; Wilcox, B. H.; Tosi,
L. P.
2019AGUFM.P21D3410O Altcode:
Exploring the depths of the Enceladus plume vents for liquid water,
searching for life is one of the larger goals of current space
exploration. Descending crevasses in ice sheets on Earth to discover
the fate of melt water runoff and its effects are of Earth science
interest. Finding a path to liquid water is the goal of any mission
seeking extant life. We present a potential solution that is adaptable
to the envelope of environmental parameters modeled. The EELS
architecture is designed to carry the latest instruments. It is
adaptable to traverse ocean world inspired terrain, fluidized media,
enclosed labyrinthian environments and liquids. It is a snake-like
self-propelled endoscope form comprising serially-replicated segments
with encapsulated locomotion and bending. Multiple segments sequentially
reverse rotations to reduce torsion in the endoscope, or replicate
rotations to perform holonomic movements for steering. The concept
is a first of its kind Archimedes screw propulsion configuration that
act as wheels, tracks, gripping mechanisms, and propelling units under
water working as propellers. These enable a robot to get to a plume and
follow the streamline to its source and proceed into the open water. In
the case of the unconsolidated plume ejected the robot is buoyant and
propelled though the loose media by the threads, even up steep slopes
and can burrow. In an open fracture system, EELS extends across the
gap near the initiation point of a fracture out of the stream line
and pushes the two end screw mechanisms on each side into the walls,
driving into the plume, then descending. In the vent the threads
bite into the side walls, reacting the plume jet forces and creating
forward movement when rotated. The robot stays on the outside of the
vent pushing on the outer walls allowing the vent streamline to pass
through the middle. The rotation of the screws is reacted by counter
rotating secondary units which provide anchoring and thrust. In the
case of wide caverns or slip of the leading screw unit, the additional
Archimedes screw units provide grip until the leading units find
their next secure position. Series elastic actuators enable us to
perform accurate force/compliance control without perfect knowledge
of the geometry of the environment; hence the robot can naturally
conform its shape to the size of the vent. This is used to move the
drive screws in any direction to maintain a desired outward force
on crack and vent walls, make the screw threads grip the surface,
direct the robot around bends, and to follow the correct branch of a
conduit across wide gaps. This architecture has never been realized
in any other robots to this point. It prioritizes reducing traversal
time to the water gas interface in case of a primary battery only
mission. Sensor arrays, cameras, and instruments at the head segment
will provide in-situ feedback.

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Title: Feasibility of a Mission to Enceladus' Subsurface Ocean for
the Next Planetary Science Decadal Survey
Authors: Hofgartner, J. D.; Choukroun, M.; Cable, M. L.; Brophy, J. R.;
Carpenter, K.; Polit Casillas, R.; Chmielewski, A. B.; Cooley, P.;
Cutts, J. A.; Fleurial, J. P.; Landau, D.; Parness, A.; Reh, K. R.;
Wilcox, B. H.
2019AGUFM.P34C..06H Altcode:
Saturn's moon Enceladus is a high priority target for astrobiology as
it harbors a subsurface ocean that erupts into space and is likely
habitable. Searching for life at Enceladus is a top priority, near
term goal of Ocean Worlds exploration (e.g., Hendrix et al., 2019,
The NASA Roadmap to Ocean Worlds, and references therein). Several
mission concepts to search for life in Enceladus' plume have been
studied including proposed Discovery and New Frontiers missions. Is
a mission that accesses the ocean and directly searches for life in
unaltered ocean samples feasible in the coming decade? We present
the results of an internal study at the Jet Propulsion Laboratory
for an ambitious yet implementable mission concept to Enceladus'
ocean. This innovative mission would include autonomous landing at
Enceladus' south pole and penetration through the ice shell via both
an intelligent melt probe and an adaptable multi-terrain robot (robotic
eel) that navigates down an erupting vent. Both the eel and melt probe
would be instrumented, able to search for evidence of life in samples
acquired during their descent, and capable of maneuvering within the
ocean. The baseline mission architecture would include a solar-powered
orbiter to identify safe, compelling landing zones and relay data to
Earth as well as an RTG-powered lander that would execute a precision
landing, deploy the melt and eel probes, relay data to the orbiter,
and also search for evidence of life in samples of surface material. A
new surface sampling system has been developed to enable the latter
search, based on experimentally-derived surface strength expectations
(Hodyss et al., this meeting). The mission design would not be inhibited
by winter darkness at Enceladus' south pole; all operations could be
accomplished at any Enceladus season. The concept would utilize the
state-of-the-art in astrodynamics techniques, systems architecture,
optimization, and advanced manufacturing. A single Flagship-level
mission that would search for life on Enceladus' surface, within its
ice shell, and in the subsurface ocean may be the most comprehensive
opportunity for astrobiology in the coming decade.

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Title: Mobile Instruments for Mars Exploration (MIMEs) (Characterizing
Recurring Slope Linea)
Authors: Carpenter, K.; Noell, A. C.; Christensen, L. E.; Zent, A.;
Quinn, R. C.
2019AGUFM.P44B..07C Altcode:
Definitive confirmation of current liquid water activity on Mars would
be a major step in establishing the present day habitability of Mars
and the possibility of extant life. The recurring slope lineae (RSL)
are one of the most intriguing targets for exploring current water
activity. The RSL are identified as seasonally dependent streaks
that darken and grow downward on steep (≥20°) slopes. Currently,
they are best explained as intergranular briny water flows percolating
through the top layers of the regolith, but orbital observations cannot
provide a definitive confirmation. However, landing and probing near
RSL presents a number of challenges to traditional mission architectures
including stringent planetary protection requirements of a Mars special
region mission. To this we propose utilizing two versions of
the Pop-Up Flat Folding Explorer Rover capable of traversing greater
than 50 degree slopes and able to be cleaned to a greater then log 7
reduction in bio burden. These will be equipped with the Thermal and
Electrical Conductivity Probe (TECP) and/or a miniature version of
the Tunable Laser Spectrometer (TLS) to characterize RSL and establish
habitability. Having multiple PUFFER agents increases the communication
range of the field survey by using individual PUFFERs as repeaters. We will determine the permafrost freeze-thaw cycle that drives
the underlying RSL processes at our field sites and characterize the
chemical makeup of the flows. This will inform on the period of liquid
phase and the available chemicals for biological processes. Overall,
the MIME mission concept addresses fundamental NASA priorities of
searching for life and habitable areas in our solar system. On Mars,
present day habitability is still fundamentally tied to finding liquid
water. The Curiosity rover has provided abundant evidence of Mars
habitability 3 - 4 billion years ago in the active lacustrine system
of Gale Crater. MIME will pursue evidence for modern day liquid flows,
and hence modern day habitability. A confirmed detection of liquid
activity near the surface of Mars would intensify the already robust
debate about the suitability of exploring Mars not only for signatures
of past life, but also for signatures of extant life.

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Title: Mars Subsurface Hydrology in 4D and Implications for Extant
Life
Authors: Stamenkovic, V.; Plesa, A. C.; Breuer, D.; Burgin, M.;
Grimm, R.; Arumugam, D.; Beauchamp, R.; Barba, N.; Manthena, R.;
Wright, D.; Wilcox, B.; Carpenter, K.; Edwards, C.
2019LPICo2108.5052S Altcode:
In this study, we show how ground-water levels might have evolved over
the last 4.5 Ga inside the martian subsurface as a function of location,
depth, and time using numerical geodynamical evolution models. We also
show how to search for them.

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Title: VizieR Online Data Catalog: ASTRAL: reference spectra for
evolved M stars (Carpenter+, 2018)
Authors: Carpenter, K. G.; Nielsen, K. E.; Kober, G. V.; Ayres, T. R.;
Wahlgren, G. M.; Rau, G.
2019yCat..18690157C Altcode:
This paper focuses on the evolved cool stars γCru and αOri and
compares their spectral characteristics to the well-studied K1.5III
star αBoo (Hinkle+ 2005uaas.book.....H). The observational strategy
for α Ori and γ Cru, as for the other objects in the ASTRAL Cool
Star Program, was crafted to find the optimal combination of spectral
resolution and signal-to-noise over the complete FUV and NUV spectra
(1150-3159Å). All of the HST Space Telescope Imaging Spectrograph
(STIS) spectra for the two objects are splined in a top-level data set
covering the entire wavelength region. An overview of the data used in
this paper is presented in Table 1, and a more detailed description
of the data, including the observing strategy, data reduction,
coaddition, and splicing, can be found on the Advances Spectral
Library (ASTRAL) website (http://casa.colorado.edu/~ayres/ASTRAL/)
and at the Mikulski Archive for Space Telescopes (MAST)
(http://archive.stsci.edu/prepds/astral/). (4 data files).

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Title: The Potential of Exozodiacal Disks Observations with the
WFIRST Coronagraph Instrument
Authors: Mennesson, B.; Bailey, V.; Kasdin, J.; Trauger, J.; Absil,
O.; Akeson, R.; Armus, L.; Baudino, J. L.; Baudoz, P.; Bellini,
A.; Bennett, D.; Berriman, B.; Boccaletti, A.; Calchi-Novati, S.;
Carpenter, K.; Chen, C.; Danchi, W.; Debes, J.; Defrere, D.; Ertel,
S.; Frerking, M.; Gelino, C.; Girard, J.; Groff, T.; Kane, S.; Helou,
G.; Kalirai, J.; Kral, Q.; Krist, J.; Kruk, J.; Hasegawa, Y.; Lagrange,
A. M.; Laine, S.; Langlois, M.; Lowrance, P.; Maire, A. L.; Malhotra,
S.; Mandell, A.; Marshall, P.; McElwain, M.; Meshkat, T.; Millan-Gabet,
R.; Moustakas, L.; Nemati, B.; Paladini, R.; Postman, M.; Pueyo, L.;
Quintana, E.; Ramirez, S.; Rhodes, J.; Riggs, A. J. E.; Rizzo, M.;
Rouan, D.; Soummer, R.; Stapelfeldt, K.; Stark, C.; Turnbull, M.; van
der Marel, R.; Vigan, A.; Ygouf, M.; Wyatt, M.; Zhao, F.; Zimmerman, N.
2019arXiv190902161M Altcode:
The Wide Field Infrared Survey Telescope (WFIRST) Coronagraph Instrument
(CGI) will be the first high-performance stellar coronagraph using
active wavefront control for deep starlight suppression in space,
providing unprecedented levels of contrast, spatial resolution, and
sensitivity for astronomical observations in the optical. One science
case enabled by the CGI will be taking images and(R~50)spectra of
faint interplanetary dust structures present in the habitable zone
of nearby sunlike stars (~10 pc) and within the snow-line of more
distant ones(~20pc), down to dust density levels commensurate with
that of the solar system zodiacal cloud. Reaching contrast levels
below~10-7 for the first time, CGI will cross an important threshold
in debris disks physics, accessing disks with low enough optical
depths that their structure is dominated by transport phenomena than
collisions. Hence, CGI results will be crucial for determining how
exozodiacal dust grains are produced and transported in low-density
disks around mature stars. Additionally, CGI will be able to measure the
brightness level and constrain the degree of asymmetry of exozodiacal
clouds around individual nearby sunlike stars in the optical, at the
~10x solar zodiacal emission level. This information will be extremely
valuable for optimizing the observational strategy of possible future
exo-Earth direct imaging missions, especially those planning to operate
at optical wavelengths, such as Habitable Exoplanet Observatory (HabEx)
and the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR).

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Title: Constraining Stellar Parameters and Atmospheric Dynamics of
the Carbon AGB star V Oph
Authors: Rau, Gioia; Ohnaka, Keiichi; Wittkowski, Markus; Airapetian,
Vladimir; Carpenter, Kenneth G.
2019ApJ...882...37R Altcode: 2019arXiv190708693R
Molecules and dust produced by the atmospheres of cool evolved stars
contribute to a significant amount of the total material found in the
interstellar medium. To understand the mechanism behind the mass loss
of these stars, it is of pivotal importance to investigate the structure
and dynamics of their atmospheres. Our goal is to verify if the extended
molecular and dust layers of the carbon-rich asymptotic giant branch
(AGB) star V Oph, and their time variations, can be explained by
dust-driven winds triggered by stellar pulsation alone, or if other
mechanisms are in play. We model V Oph mid-infrared interferometric
VLTI-MIDI data (8-13 μm), at phases 0.18, 0.49, and 0.65, together with
literature photometric data, using the latest-generation self-consistent
dynamic atmosphere models for carbon-rich stars: DARWIN. We determine
the fundamental stellar parameters: T eff = 2600 K, L
bol = 3585 L ⊙, M = 1.5 M ⊙,
C/O = 1.35, \dot{M}=2.50× {10}-6 M ⊙
yr-1. We calculate the stellar photospheric radii at the
three phases: 479, 494, 448 R ⊙ and the dust radii: 780,
853, 787 R ⊙. The dynamic models can fairly explain
the observed N-band visibility and spectra, although there is some
discrepancy between the data and the models, which is discussed in the
text. We discuss the possible causes of the temporal variations of the
outer atmosphere, deriving an estimate of the magnetic field strength,
and computing upper limits for the Alfvén waves velocity. In addition,
using period-luminosity sequences, and interferometric modeling, we
suggest V Oph as a candidate to be reclassified as a semi-regular star.

---------------------------------------------------------
Title: Stars at High Spatial Resolution
Authors: Carpenter, Kenneth G.; van Belle, Gerard; Brown, Alexander;
Cranmer, Steven R.; Drake, Jeremy; Dupree, Andrea K.; Creech-Eakman,
Michelle; Evans, Nancy R.; Grady, Carol A.; Guinan, Edward F.; Harper,
Graham; Karovska, Margarita; Kolenberg, Katrien; Labeyrie, Antoine;
Linsky, Jeffrey; Peters, Geraldine J.; Rau, Gioia; Ridgway, Stephen;
Roettenbacher, Rachael M.; Saar, Steven H.; Walter, Frederick M.;
Wood, Brian
2019arXiv190805665C Altcode:
We summarize some of the compelling new scientific opportunities
for understanding stars and stellar systems that can be enabled by
sub-milliarcsec (sub-mas) angular resolution, UV-Optical spectral
imaging observations, which can reveal the details of the many dynamic
processes (e.g., evolving magnetic fields, accretion, convection,
shocks, pulsations, winds, and jets) that affect stellar formation,
structure, and evolution. These observations can only be provided
by long-baseline interferometers or sparse aperture telescopes in
space, since the aperture diameters required are in excess of 500 m
(a regime in which monolithic or segmented designs are not and will
not be feasible) and since they require observations at wavelengths
(UV) not accessible from the ground. Such observational capabilities
would enable tremendous gains in our understanding of the individual
stars and stellar systems that are the building blocks of our Universe
and which serve as the hosts for life throughout the Cosmos.

---------------------------------------------------------
Title: Understanding Component/Materials Performance in the Lunar
Environment
Authors: Patterson, M. C. L.; Tucker, J.; Carpenter, K.; Parness, A.
2019LPICo2152.5056P Altcode:
A test environment that closely approximates the lunar surface has
been established to characterize the wear and degradation mechanisms
associated with components such as gear boxes, predict performance,
and establish mitigation strategies.

---------------------------------------------------------
Title: Cool, evolved stars: results, challenges, and promises for
the next decade
Authors: Rau, Gioia; Montez, Rodolfo, Jr.; Carpenter, Kenneth;
Wittkowski, Markus; Bladh, Sara; Karovska, Margarita; Airapetian,
Vladimir; Ayres, Tom; Boyer, Martha; Chiavassa, Andrea; Clayton,
Geoffrey; Danchi, William; De Marco, Orsola; Dupree, Andrea K.;
Kaminski, Tomasz; Kastner, Joel H.; Kerschbaum, Franz; Linsky,
Jeffrey; Lopez, Bruno; Monnier, John; Montargès, Miguel; Nielsen,
Krister; Ohnaka, Keiichi; Ramstedt, Sofia; Roettenbacher, Rachael;
ten Brummelaar, Theo; Paladini, Claudia; Sarangi, Arkaprabha; van
Belle, Gerard; Ventura, Paolo
2019BAAS...51c.241R Altcode: 2019arXiv190304585R; 2019astro2020T.241R
This White Paper identifies compelling scientific opportunities in
the field of Cool, Evolved Stars, describing the observational and
theoretical challenges to our understanding, and the key advancements
made. We portray the pathway towards understanding, and identify,
through recommendations, which advancements are necessary in 2020-2030
&amp; beyond.

---------------------------------------------------------
Title: Stars at High Spatial Resolution
Authors: Carpenter, Kenneth; van Belle, Gerard; Brown, Alexander;
Cranmer, Steven R.; Drake, Jeremy; Dupree, Andrea K.; Creech-Eakman,
Michelle; Evans, Nancy R.; Grady, Carol A.; Guinan, Edward F.; Harper,
Graham; Karovska, Margarita; Kolenberg, Katrien; Labeyrie, Antoine;
Linsky, Jeffrey; Peters, Geraldine J.; Rau, Gioia; Ridgway, Stephen;
Roettenbacher, Rachael M.; Saar, Steven H.; Walter, Frederick M.;
Wood, Brian
2019BAAS...51c..56C Altcode: 2019astro2020T..56C
We summarize compelling new scientific opportunities for understanding
stars and stellar systems that can be enabled by sub-milliarcsec angular
resolution, UV/Optical spectral imaging observations. These can reveal
details of many dynamic processes that affect stellar formation,
structure, and evolution.

---------------------------------------------------------
Title: High Angular Resolution Astrophysics: Resolving Stellar
Surface Features
Authors: Roettenbacher, Rachael; Norris, Ryan; Baron, Fabien;
Carpenter, Kenneth; Creech-Eakman, Michelle; Gies, Douglas; Maccarone,
Thomas; Monnier, John; Rau, Gioia; Ridgway, Stephen; Schaefer, Gail;
ten Brummelaar, Theo
2019BAAS...51c.181R Altcode: 2019arXiv190304660R; 2019astro2020T.181R
We discuss the main types of stars for which imaging surface features
is currently possible using long-baseline optical interferometry and
what improved observing techniques would provide for imaging stellar
surface features.

---------------------------------------------------------
Title: Characterizing Component Performance in the Lunar Environment
Authors: Patterson, M. C. L.; Tucker, J.; Carpenter, K.; Parness, A.
2019LPI....50.2756P Altcode:
Understanding how systems perform on planetary surfaces is critical to
mission success. Simulated lunar environments allow accurate component
life predictions.

---------------------------------------------------------
Title: The Wide Field Infrared Survey Telescope: 100 Hubbles for
the 2020s
Authors: Akeson, Rachel; Armus, Lee; Bachelet, Etienne; Bailey,
Vanessa; Bartusek, Lisa; Bellini, Andrea; Benford, Dominic; Bennett,
David; Bhattacharya, Aparna; Bohlin, Ralph; Boyer, Martha; Bozza,
Valerio; Bryden, Geoffrey; Calchi Novati, Sebastiano; Carpenter,
Kenneth; Casertano, Stefano; Choi, Ami; Content, David; Dayal,
Pratika; Dressler, Alan; Doré, Olivier; Fall, S. Michael; Fan,
Xiaohui; Fang, Xiao; Filippenko, Alexei; Finkelstein, Steven; Foley,
Ryan; Furlanetto, Steven; Kalirai, Jason; Gaudi, B. Scott; Gilbert,
Karoline; Girard, Julien; Grady, Kevin; Greene, Jenny; Guhathakurta,
Puragra; Heinrich, Chen; Hemmati, Shoubaneh; Hendel, David; Henderson,
Calen; Henning, Thomas; Hirata, Christopher; Ho, Shirley; Huff,
Eric; Hutter, Anne; Jansen, Rolf; Jha, Saurabh; Johnson, Samson;
Jones, David; Kasdin, Jeremy; Kelly, Patrick; Kirshner, Robert;
Koekemoer, Anton; Kruk, Jeffrey; Lewis, Nikole; Macintosh, Bruce;
Madau, Piero; Malhotra, Sangeeta; Mandel, Kaisey; Massara, Elena;
Masters, Daniel; McEnery, Julie; McQuinn, Kristen; Melchior, Peter;
Melton, Mark; Mennesson, Bertrand; Peeples, Molly; Penny, Matthew;
Perlmutter, Saul; Pisani, Alice; Plazas, Andrés; Poleski, Radek;
Postman, Marc; Ranc, Clément; Rauscher, Bernard; Rest, Armin; Roberge,
Aki; Robertson, Brant; Rodney, Steven; Rhoads, James; Rhodes, Jason;
Ryan, Russell, Jr.; Sahu, Kailash; Sand, David; Scolnic, Dan; Seth,
Anil; Shvartzvald, Yossi; Siellez, Karelle; Smith, Arfon; Spergel,
David; Stassun, Keivan; Street, Rachel; Strolger, Louis-Gregory;
Szalay, Alexander; Trauger, John; Troxel, M. A.; Turnbull, Margaret;
van der Marel, Roeland; von der Linden, Anja; Wang, Yun; Weinberg,
David; Williams, Benjamin; Windhorst, Rogier; Wollack, Edward; Wu,
Hao-Yi; Yee, Jennifer; Zimmerman, Neil
2019arXiv190205569A Altcode:
The Wide Field Infrared Survey Telescope (WFIRST) is a 2.4m space
telescope with a 0.281 deg^2 field of view for near-IR imaging and
slitless spectroscopy and a coronagraph designed for &gt; 10^8 starlight
suppresion. As background information for Astro2020 white papers,
this article summarizes the current design and anticipated performance
of WFIRST. While WFIRST does not have the UV imaging/spectroscopic
capabilities of the Hubble Space Telescope, for wide field near-IR
surveys WFIRST is hundreds of times more efficient. Some of the most
ambitious multi-cycle HST Treasury programs could be executed as
routine General Observer (GO) programs on WFIRST. The large area and
time-domain surveys planned for the cosmology and exoplanet microlensing
programs will produce extraordinarily rich data sets that enable an
enormous range of Archival Research (AR) investigations. Requirements
for the coronagraph are defined based on its status as a technology
demonstration, but its expected performance will enable unprecedented
observations of nearby giant exoplanets and circumstellar disks. WFIRST
is currently in the Preliminary Design and Technology Completion phase
(Phase B), on schedule for launch in 2025, with several of its critical
components already in production.

---------------------------------------------------------
Title: M-Giant Mass-Loss Rates and Wind Parameters from UV Emission
Line Profiles
Authors: Carpenter, Kenneth G.; Rau, Gioia; Nielsen, Krister E.
2019AAS...23336506C Altcode:
Strong chromospheric emission lines in the UV spectra of M giants show
superposed absorption features created by their photon-scattering
winds. These self-reversed emission profiles provide us with an
opportunity to assess important parameters of the wind, including
flow and turbulent velocities, the optical depth of the wind above
the region of photon creation, and the star's mass-loss rate. We use
the Sobolev with Exact Integration (SEI) radiative transfer code,
along with simple models of the outer atmospheric structure and
wind, to determine the wind characteristics of the two M-giant stars
Gamma Cru (M3.4) and Mu Gem (M3IIIab). We use this code because it
is computationally fast and allows a great number of possible wind
models to be examined. The program calculates line profiles for the
Mg II (UV1) lines and a range of unblended Fe II lines. These lines
represent a wide range of wind opacities, and thus different heights
in the atmosphere. The assumed wind properties are iterated, until
the predicted profiles match the observations (in this case HST/GHRS
UV spectra), over as many lines as possible. We present estimates of
the wind parameters for these two M-giant stars, and offer a comparison
to wind properties previously-determined for low-gravity K stars using
the same technique and similar data.

---------------------------------------------------------
Title: Key Technologies for the Wide Field Infrared Survey Telescope
Coronagraph Instrument
Authors: Bailey, Vanessa P.; Armus, Lee; Balasubramanian, Bala;
Baudoz, Pierre; Bellini, Andrea; Benford, Dominic; Berriman, Bruce;
Bhattacharya, Aparna; Boccaletti, Anthony; Cady, Eric; Calchi Novati,
Sebastiano; Carpenter, Kenneth; Ciardi, David; Crill, Brendan; Danchi,
William; Debes, John; Demers, Richard; Dohlen, Kjetil; Effinger,
Robert; Ferrari, Marc; Frerking, Margaret; Gelino, Dawn; Girard,
Julien; Grady, Kevin; Groff, Tyler; Harding, Leon; Helou, George;
Henning, Avenhaus; Janson, Markus; Kalirai, Jason; Kane, Stephen;
Kasdin, N. Jeremy; Kenworthy, Matthew; Kern, Brian; Krist, John;
Kruk, Jeffrey; Lagrange, Anne Marie; Laine, Seppo; Langlois, Maud;
Le Coroller, Herve; Lindensmith, Chris; Lowrance, Patrick; Maire,
Anne-Lise; Malhotra, Sangeeta; Mandell, Avi; McElwain, Michael;
Mejia Prada, Camilo; Mennesson, Bertrand; Meshkat, Tiffany; Moody,
Dwight; Morrissey, Patrick; Moustakas, Leonidas; N'Diaye, Mamadou;
Nemati, Bijan; Noecker, Charley; Paladini, Roberta; Perrin, Marshall;
Poberezhskiy, Ilya; Postman, Marc; Pueyo, Laurent; Ramirez, Solange;
Ranc, Clement; Rhodes, Jason; Riggs, A. J. E.; Rizzo, Maxime; Roberge,
Aki; Rouan, Daniel; Schlieder, Joshua; Seo, Byoung-Joon; Shaklan,
Stuart; Shi, Fang; Soummer, Remi; Spergel, David; Stapelfeldt, Karl;
Stark, Christopher; Tamura, Motohide; Tang, Hong; Trauger, John;
Turnbull, Margaret; van der Marel, Roeland; Vigan, Arthur; Williams,
Benjamin; Wollack, Edward J.; Ygouf, Marie; Zhao, Feng; Zhoud, Hanying;
Zimmerman, Neil
2019arXiv190104050B Altcode:
The Wide Field Infrared Survey Telescope (WFIRST) Coronagraph Instrument
(CGI) is a high-contrast imager and integral field spectrograph
that will enable the study of exoplanets and circumstellar disks at
visible wavelengths. Ground-based high-contrast instrumentation has
fundamentally limited performance at small working angles, even under
optimistic assumptions for 30m-class telescopes. There is a strong
scientific driver for better performance, particularly at visible
wavelengths. Future flagship mission concepts aim to image Earth
analogues with visible light flux ratios of more than 10^10. CGI
is a critical intermediate step toward that goal, with a predicted
10^8-9 flux ratio capability in the visible. CGI achieves this through
improvements over current ground and space systems in several areas:
(i) Hardware: space-qualified (TRL9) deformable mirrors, detectors,
and coronagraphs, (ii) Algorithms: wavefront sensing and control;
post-processing of integral field spectrograph, polarimetric, and
extended object data, and (iii) Validation of telescope and instrument
models at high accuracy and precision. This white paper, submitted to
the 2018 NAS Exoplanet Science Strategy call, describes the status of
key CGI technologies and presents ways in which performance is likely
to evolve as the CGI design matures.

---------------------------------------------------------
Title: HST/GHRS Observations of Cool, Low-gravity Stars. VI. Mass-loss
Rates and Wind Parameters for M Giants
Authors: Rau, Gioia; Nielsen, Krister E.; Carpenter, Kenneth G.;
Airapetian, Vladimir
2018ApJ...869....1R Altcode: 2018arXiv181110679R
The photon-scattering winds of M giants absorb parts of the
chromospheric emission lines and produce self-reversed spectral features
in high-resolution Hubble Space Telescope (HST)/GHRS spectra. These
spectra provide an opportunity to assess fundamental parameters of the
wind, including flow and turbulent velocities, the optical depth of the
wind above the region of photon creation, and the star’s mass-loss
rate. This paper is the last paper in the series “GHRS Observations
of Cool, Low-Gravity Stars” the last several have compared empirical
measurements of spectral emission lines with models of the winds and
mass loss of K giants and supergiants. We have used the Sobolev with
Exact Integration radiative transfer code, along with simple models
of the outer atmosphere and wind, to determine and compare the wind
characteristics of the two M-giant stars, γ Cru (M3.5III) and μ Gem
(M3IIIab), with previously derived values for low-gravity K-stars. The
analysis specifies the wind parameters and calculates line profiles
for the Mg II resonance lines, in addition to a range of unblended
Fe II lines. Our line sample covers a large range of wind opacities
and, therefore, probes a range of heights in the atmosphere. Our
results show that μ Gem has a slower and more turbulent wind than γ
Cru. Also, μ Gem has a weaker chromosphere, in terms of surface flux,
with respect to γ Cru. This suggests that μ Gem is more evolved
than γ Cru. Comparing the two M giants in this work with previously
studied K-giant and supergiant stars (α Tau, γ Dra, and λ Vel)
reveals that the M giants have slower winds than the earlier giants,
but exhibit higher mass-loss rates. Our results are interpreted in
the context of the winds being driven by Alfvén waves.

---------------------------------------------------------
Title: The Advanced Spectral Library (ASTRAL): Reference Spectra
for Evolved M Stars
Authors: Carpenter, Kenneth G.; Nielsen, Krister E.; Kober, Gladys V.;
Ayres, Thomas R.; Wahlgren, Glenn M.; Rau, Gioia
2018ApJ...869..157C Altcode: 2018arXiv181111865C
The HST Treasury Program Advanced Spectral Library Project: Cool Stars
was designed to collect representative, high-quality UV spectra of eight
evolved F-M type cool stars. The Space Telescope Imaging Spectrograph
(STIS) echelle spectra of these objects enable investigations of a broad
range of topics, including stellar and interstellar astrophysics. This
paper provides a guide to the spectra of the two evolved M stars, the
M2 Iab supergiant α Ori and the M3.4 giant γ Cru, with comparisons to
the prototypical K1.5 giant α Boo. It includes identifications of the
significant atomic and molecular emission and absorption features and
discusses the character of the photospheric and chromospheric continua
and line spectra. The fluorescent processes responsible for a large
portion of the emission-line spectrum, the characteristics of the
stellar winds, and the available diagnostics for hot and cool plasmas
are also summarized. This analysis will facilitate the future study of
the spectra, outer atmospheres, and winds, not only of these objects
but of numerous other cool, low-gravity stars, for years to come. Based on observations with the NASA/ESA Hubble Space Telescope
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities for Research in Astronomy, Inc.,
under NASA contract NAS5-26555.

---------------------------------------------------------
Title: Shifting the Paradigm of Coping with Nyx on the Moon — a
Ground-Penetrating Radar Case
Authors: Nunes, D. C.; Carpenter, K.; Haynes, M.; de la Croix, J. P.
2018LPICo2106.7012N Altcode:
A multi-static, autonomous ground-penetrating radar instrument, MARGE,
will incorporate strategies to be more tolerant of the lunar diurnal
thermal cycle.

---------------------------------------------------------
Title: The Mass of the Cepheid V350 Sgr
Authors: Evans, Nancy Remage; Proffitt, Charles; Carpenter, Kenneth G.;
Winston, Elaine M.; Kober, Gladys V.; Günther, H. Moritz; Gorynya,
Natalia; Rastorguev, Alexey; Inno, L.
2018ApJ...866...30E Altcode: 2018arXiv180810472E
V350 Sgr is a classical Cepheid suitable for mass determination. It has
a hot companion which is prominent in the ultraviolet (UV) and which
is not itself a binary. We have obtained two high-resolution echelle
spectra of the companion at orbital velocity maximum and minimum with
the Space Telescope Imaging Spectrograph on the Hubble Space Telescope
in the 1320 to 1510 Å region. By cross-correlating these spectra
we obtained the orbital velocity amplitude of the companion with an
uncertainty in the companion amplitude of 1.9 km s-1. This
provides a mass ratio of the Cepheid to the companion of 2.1. The UV
energy distribution of the companion provides the mass of the companion,
yielding a Cepheid mass of 5.2 ± 0.3 M ⊙. This mass
requires some combination of moderate main sequence core convective
overshoot and rotation to match evolutionary tracks. Based on
observations with the NASA/ESA Hubble Space Telescope obtained at the
Space Telescope Science Institute, which is operated by the Association
of Universities for Research in Astronomy, Inc., under NASA contract
NAS5-26555.

---------------------------------------------------------
Title: Imaging the Surfaces of Stars from Space
Authors: Carpenter, Kenneth; Rau, Gioia
2018iss..confE...4C Altcode:
Imaging of Stellar Surfacess has been dominated to-date by ground-based
observations, but space-based facilities offer tremendous potential for
extending the wavelength coverage and ultimately the resolution of such
efforts. We review the imaging accomplished so far from space and then
talk about exciting future prospects. The earliest attempts from space
indirectly produced surface maps via the Doppler Imaging Technique,
using UV spectra obtained with the International Ultraviolet Explorer
(IUE). Later, the first direct UV images were obtained with the Hubble
Space Telescope (HST), of Mira and Betelgeuse, using the Faint Object
Camera (FOC). We will show this work and then investigate prospects
for IR imaging with the James Webb Space Telescope (JWST). The real
potential of space-based Imaging of Stellar Surfacess, however, lies
in the future, when large-baseline Fizeau interferometers, such as the
UV-optical Stellar Imager (SI) Vision Mission, with a 30-element array
and 500m max baseline, are flown. We describe SI and its science goals,
which include 0.1 milli-arcsec spectral Imaging of Stellar Surfacess
and the probing of internal structure and flows via asteroseismology.

---------------------------------------------------------
Title: The WFIRST Exoplanet Microlensing Survey
Authors: Bennett, David P.; Akeson, Rachel; Anderson, Jay; Armus,
Lee; Bachelet, Etienne; Bailey, Vanessa; Barclay, Thomas; Barry,
Richard; Beaulieu, Jean-Phillipe; Belini, Andrea; Benford, Dominic
J.; Bhattacharya, Aparna; Boyd, Padi; Bozza, Valerio; Calchi Novati,
Sebastiano; Carpenter, Kenneth; Cassan, Arnaud; Ciardi, David; Cole,
Andrew; Colon, Knicole; Coutures, Christian; Dominik, Martin; Fouque,
Pascal; Grady, Kevin; Groff, Tyler; Henderson, Calen B.; Horne,
Keith; Gelino, Christopher; Gelino, Dawn; Kalirai, Jason; Kane,
Stephen; Kasdin, N. Jeremy; Kruk, Jeffrey; Laine, Seppo; Lambrechts,
Michiel; Mancini, Luigi; Mandell, Avi; Malhotra, Sangeeta; Mao, Shude;
McElwain, Michael; Mennesson, Bertrand; Meshkat, Tiffany; Moustakas,
Leonidas; Munoz, Jose A.; Nataf, David; Paladini, Roberta; Pascucci,
Ilaria; Penny, Matthew; Poleski, Radek; Quintana, Elisa; Ranc, Clement;
Rattenbury, Nicholas; Rhodes, James; Rhodes, Jason D.; Rizzo, Maxime;
Roberge, Aki; Rogers, Leslie; Sahu, Kailash C.; Schlieder, Joshua;
Seager, Sara; Shvartzvald, Yossi; Soummer, Remi; Spergel, David;
Stassun, Keivan G.; Street, Rachel; Sumi, Takahiro; Suzuki, Daisuke;
Trauger, John; van der Marel, Roeland; Williams, Benjamin F.; Wollack,
Edward J.; Yee, Jennifer; Yonehara, Atsunori; Zimmerman, Neil
2018arXiv180308564B Altcode:
The Wide Field Infrared Survey Telescope (WFIRST) was the top ranked
large space mission in the 2010 New Worlds, New Horizons decadal survey,
and it was formed by merging the science programs of 3 different
mission concepts, including the Microlensing Planet Finder (MPF)
concept (Bennett \etal\ 2010). The WFIRST science program (Spergel
\etal\ 2015) consists of a general observer program, a wavefront
controlled technology program, and two targeted science programs: a
program to study dark energy, and a statistical census of exoplanets
with a microlensing survey, which uses nearly one quarter of WFIRST's
observing time in the current design reference mission. The New Worlds,
New Horizons (decadal survey) midterm assessment summarizes the science
case for the WFIRST exoplanet microlensing survey with this statement:
"WFIRST's microlensing census of planets beyond 1 AU will perfectly
complement Kepler's census of compact systems, and WFIRST will also
be able to detect free-floating planets unbound from their parent
stars\rlap."

---------------------------------------------------------
Title: Weighing supermassive black holes with the UV photon sieve
space telescope
Authors: Airapetian, Vladimir; Upton, Robert S.; Davila, Joseph;
Marzouk, Marzouk; Carpenter, Kenneth G.; Weaver, Kimberly
2017SPIE10564E..3RA Altcode:
The Photon Sieve Space Telescope (PSST) is a space-based ultra
high-resolution (5 mas) narrow band (λ/Δλ ≃ 1000) spectral UV
imager providing spectral imaging of astronomical objects in Ly - ,
CIV and NV emission lines. Science obtained with this telescope will
revolutionize our understanding of a whole range of astrophysical
processes in the local and distant universe. There will be a dramatic
increase in the number of observed moderate and large SMBH masses as
well as extra-solar protoplanetary disks. The observations will also
enable tracing the star formation rates in active galaxies. We present
the optical design, the properties and the future implementation of
the proposed UV photon sieve space telescope.

---------------------------------------------------------
Title: Detecting the Beacons of Life with Exo-Life Beacon Space
Telescope (ELBST)
Authors: Airapetian, V. S.; Danchi, W. C.; Chen, P. C.; Rabin, D. M.;
Carpenter, K. G.; Mlynczak, M. G.
2017LPICo1989.8214A Altcode:
We propose a new observational strategy, the “Exo-Life Beacon Space
Telescope,” for detecting the signatures of “beacons” of life
defined as high signal and low spectral resolution thermal emission
from molecules associated with life signatures.

---------------------------------------------------------
Title: Bridging the Gap between Coronal and Non-Coronal Evolved Stars
Authors: Carpenter, Kenneth G.; Nielsen, Krister E.; Kober, Gladys V.
2017AAS...22915102C Altcode:
The Hubble Space Telescope (HST) Treasury Program "Advanced Spectral
Library (ASTRAL)" enables investigations of a broad range of problems
including the character and dynamics of the wind and chromosphere
of cool stars. This paper presents an investigation of the change in
spectral characteristics when transitioning from the cool non-coronal
objects with fluorescent emission spectra from the iron group elements,
molecular hydrogen, and carbon monoxide to the warmer stars on the
blue side of the Linsky-Haish dividing line in the HR diagram. These
warmer objects exhibit chromospheric emission from significantly
hotter environments in addition to coronal signatures, while the hybrid
stars overlap in the HR-diagram with some of the non-coronal objects
and share many spectral characteristics but show differences in the
wind properties. We show how the wind, fluorescent features, and hot
stellar signatures dramatically change with spectral class by comparing
the already analyzed non-coronal objects (Alpha Ori, Gamma Cru) with
the hybrid stars (Gamma Dra, Beta Gem and Alpha Aqr) and the coronal
object Beta Dra. We aim to gain understanding of the physical processes
in these objects' outer atmospheres and their evolutionary tracks.

---------------------------------------------------------
Title: A Precision Measurement of the Mass of the Cepheid V350 Sgr
Authors: Evans, Nancy Remage; Bono, Giuseppe; Carpenter, Kenneth G.;
Gorynya, Natashya; Inno, Laura; Proffitt, Charles R.; Rastorgouev,
Alexey
2016hst..prop14332E Altcode:
An important HST UV legacy is the measurement of the masses of
Cepheids. HST has provided double-lined spectroscopic binaries since the
orbital velocity amplitude of hot companions can be measured on high
resolution ultraviolet spectra. STIS UV E140H echelle observations of
the Cepheid V350 Sgr will yield a dramatic improvement in the precision
of its mass (5% or 0.25 solar masses vs the current 17%). This will
allow a unique and critical test of the role of convective overshoot
in the evolution of intermediate mass stars, by coupling the measured
mass with a luminosity. Furthermore, the very accurate masses (1-2%)
recently determined for two Cepheids in eclipsing binaries in the LMC
mean the mass--luminosity relation for Cepheids can be compared for
two metallicities. This will improve both confidence in the use of
Cepheids as primary extragalactic distance indicators and also our
understanding of the evolution of intermediate mass stars.

---------------------------------------------------------
Title: PUFFER (Pop-Up Flat Folding Explorer Robots)
Authors: Karras, J.; Carpenter, K.; Fuller, C.; Parcheta, C.
2016LPICo1980.4125K Altcode:
PUFFER (Pop-Up Flat Folding Explorer Robots) are origami-inspired
folding robots with extreme terrain mobility. PUFFERs are low-volume,
low-mass, and low-cost robots for high-reward extreme terrain science.

---------------------------------------------------------
Title: Highlights of IAU Commission 29: Recent Advances and
Perspectives on Stellar Spectroscopy
Authors: Cunha, Katia; Soderblom, David R.; Piskunov, Nikolai; Aoki,
Wako; Asplund, Martin; Carpenter, Kenneth G.; Crowther, Paul; Melendez,
Jorge; Venn, Kimberly; Hill, Vanessa; Yong, David
2016IAUTA..29..428C Altcode:
IAU Commission 29 - Stellar Spectra has been one of the IAU commissions
from the onset, until its dissolution at the most recent IAU General
Assembly in Honolulu in 2015. This commission belonged to IAU Division
G (“Stars and Stellar Physics”), the latter committed with fostering
research in stellar astrophysics. Within the general field of stellar
astrophysics, stellar spectroscopy plays a key role, as stellar
spectra are a powerful tool providing a view into the detailed physical
properties of stars and the physical processes occuring within them.

---------------------------------------------------------
Title: Lithium in Open Cluster Red Giants Hosting Substellar
Companions
Authors: Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Carpenter,
Kenneth G.
2016ApJ...818...25C Altcode: 2015arXiv151208558C
We have measured stellar parameters, [Fe/H], lithium abundances,
rotation, and 12C/13C in a small sample of
red giants (RGs) in three open clusters that are each home to
a RG star that hosts a substellar companion (SSC) (NGC 2423 3,
NGC 4349 127, and BD+12 1917 in M67). Our goal is to explore
whether the presence of SSCs influences the Li content. Both
12C/13C and stellar rotation are measured as
additional tracers of stellar mixing. One of the companion hosts,
NGC 2423 3, is found to be Li-rich with A(Li){}{{NLTE}} =
1.56 dex, and this abundance is significantly higher than the A(Li)
of the two comparison stars in NGC 2423. All three SSC hosts have the
highest A(Li) and 12C/13C when compared to the
control RGs in their respective clusters; however, except for NGC 2423
3, at least one control star has similarly high abundances within the
uncertainties. Higher A(Li) could suggest that the formation or presence
of planets plays a role in the degree of internal mixing on or before
the RG branch. However, a multitude of factors affect A(Li) during the
RG phase, and when the abundances of our sample are compared with the
abundances of RGs in other open clusters available in the literature,
we find that they all fall well within a much larger distribution of
A(Li) and 12C/13C. Thus, even the high Li in
NGC 2423 3 cannot be concretely tied to the presence of the SSC.

---------------------------------------------------------
Title: The Advanced Spectral Library (ASTRAL): Abundance Analysis
of the CP Star HR 465
Authors: Carpenter, Kenneth G.; Nielsen, Krister E.; Kober, Gladys V.
2016AAS...22743401C Altcode:
We present the results of a spectrum analysis of the prototypical
A-type magnetic CP star HR465. Synthetic spectra, using an non-LTE
atmosphere model, were generated to fit high-resolution ultraviolet
spectra (1200-3100 A) obtained as a part of the "Advanced Spectral
Library (ASTRAL) Project: Hot Stars" program (GO-13346: Ayres
PI). The ultraviolet data were supplemented by high resolution
optical data recorded at the Nordic Optical Telescope with the SOFIN
spectrograph. The optical data was used as a complement to the high
line density ultraviolet spectrum and primarily used to derive accurate
iron-group element abundances.HR 465 has previously been analyzed
using IUE spectra. We revisit the object with this high quality
data. Large parts of the spectrum have been synthesized with an ATLAS
model (Teff=10750K, logg=4.0) and we present abundance results for more
than 50 elements. We can confirm some of the abundance characteristics
previously derived from IUE data, where elements heavier than Z=30
show significant abundance enhancements compared to solar values,
while some of the lighter elements show abundance deficiencies. We
will place these results in context of other AP stars, and the large
number of element abundances will also help us to put some constraint
on stellar abundance and evolution theories.

---------------------------------------------------------
Title: The Magnetic Coupling of Chromospheres and Winds From Late
Type Evolved Stars: Role of MHD Waves
Authors: Airapetian, Vladimir; Leake, James; Carpenter, Kenneth
2015IAUGA..2190977A Altcode:
Stellar chromospheres and winds represent universal attributes
of stars on the cool portion of H-R diagram. In this paper we
derive observational constrains for the chromospheric heating and
wind acceleration from cool evolved stars and examine the role of
Alfven waves as a viable source of energy dissipation and momentum
deposition. We use a 1.5D magnetohydrodynamic code with a generalized
Ohm's law to study propagation of Alfven waves generated along
a diverging magnetic field in a stellar photosphere at a single
frequency. We demonstrate that due to inclusion of the effects of
ion-neutral collisions in magnetized weakly ionized chromospheric
plasma on resistivity and the appropriate grid resolution, the numerical
resistivity becomes 1-2 orders of magnitude smaller than the physical
resistivity. The motions introduced by non-linear transverse Alfven
waves can explain non-thermally broadened and non-Gaussian profiles
of optically thin UV lines forming in the stellar chromosphere of
α Tau and other late-type giant and supergiant stars. The calculated
heating rates in the stellar chromosphere model due to resistive (Joule)
dissipation of electric currents on Pedersen resistivity are consistent
with observational constraints on the net radiative losses in UV lines
and the continuum from α Tau. At the top of the chromosphere, Alfven
waves experience significant reflection, producing downward propagating
transverse waves that interact with upward propagating waves and produce
velocity shear in the chromosphere. Our simulations also suggest that
momentum deposition by non-linear Alfven waves becomes significant in
the outer chromosphere within 1 stellar radius from the photosphere
that initiates a slow and massive winds from red giants and supergiants.

---------------------------------------------------------
Title: The abundance pattern of heavy elements in Sirius: Impact of
modern observations (STIS) and improved Atomic data
Authors: Ramsay Cowley, Charles; Ayres, Thomas; Wahlgren, Glenn;
Carpenter, Kenneth
2015IAUGA..2236931R Altcode:
The abundance pattern of heavy elements in Sirius: Impact of modern
observations (STIS) and improved atomic data. We determine abundances
or upper limits for the 55 stable elements from copper to uranium for
the A1 Vm star Sirius. The primary observational material consists of
Hubble Space Telescope (HST) spectra taken with the Space Telescope
Imaging Spectrograph (STIS) from the ASTRAL project (Ayres 2010,
ApJS, 187, 149). We have also used archival material from COPERNICUS
(retrieved from the MAST) and from HST/GHRS, as well as the ground-based
Furenlid, Westin, and Kurucz Sirius Atlas (FWK). The GHRS observations
were described by Wahlgren, et al. (1993, Bull. AAS, 25, 1321). We
also used the monumental study of Sirius by Klaus Kohl (1964,
Zs. f. Ap. 60, 115, 1964, see also 1964, Das Spektrum des Sirius,
3100 - 8863A, Kiel thesis). Abundance determinations are based on
the photospheric model of Landstreet (2011, A&amp;A, 528, 132). The
atomic data base is significantly improved since the pioneering work
by Sadakane (1988, PASP, 100, 811; 1991, 103, 355). The basic source
was VALD3 (http://vald.inasan.ru/~vald3/php/vald.php), supplemented
for all species by the essential NIST bibliographic data base
(http://physics.nist.gov/cgi-bin/ASBib1/TransProbBib.cgi). We determine
abundances and upper limits by synthesizing short wavelength regions
around strong lines. Virtually all of the abundance/upper limit results
show excesses over the solar composition of between 1 and 2 dex. This
result is in general agreement with overall results for metallic line
stars, though we have no information on possible severe depletions
for most elements. We conclude that the mechanisms causing abundance
anomalies in Sirius have not acted to produce the extreme excesses of 4
or more dex (Pt, Hg), or deficiencies (Zn) seen in many HgMn stars.CRC
thanks Stefano Bagnulo for the UVESPOP Sirius spectrum. Robert Kurucz
was most helpful with older Sirius UV and visual spectra.

---------------------------------------------------------
Title: Fluorescence Processes in the Outer Atmospheres of the Evolved
M-Stars Alpha Ori (M2 Iab) and Gamma Cru (M3.4 III)
Authors: Carpenter, Kenneth; Kober, Gladys; Nielsen, Krister; Ayres,
Thomas; Wahlgren, Glenn
2015IAUGA..2242446C Altcode:
The prototypical M-giant and M-supergiant stars, Gamma Cru (M3.4
III)) and Alpha Ori (M2Iab), have been observed as part of the
"Advanced Spectral Library (ASTRAL) Project: Cool Stars" (PI =
T. Ayres). "ASTRAL-Cool Stars" is an HST Cycle 18 Treasury Program
designed to collect, using the Space Telescope Imaging Spectrograph
(STIS), a definitive set of representative, high-resolution (R~46,000
in the FUV up to ~1700 Å, R~30,000 for 1700-2150 Å, and R~114,000
&gt;2150 Å) and high signal/noise (S/N&gt;100) UV spectra of eight F-M
evolved cool stars. These extremely high-quality UV echelle spectra
are available from the HST archive and through the University of
Colorado (http://casa.colorado.edu/~ayres/ASTRAL/). In this paper,
we use the very rich emission-line spectra of the two evolved M stars
in the sample, Gamma Cru (GaCrux) and Alpha Ori (Betelgeuse), to study
the fluorescence processes operating in their outer atmospheres. We
summarize the pumping transitions and fluorescent line products known
on the basis of previous work and newly identified in our on-going
analysis of these extraordinary new “Treasury” spectra. Detailed
descriptions of selected processes are given to illustrate their
operation. The wide variety of fluorescence processes in operation in
these outer atmospheres, both molecular and atomic, suggest that there
is a mixture of warm and cool plasmas present and that H I Ly-alpha in
particular is locally very strong, even though, in the case of Alpha
Ori, no flux is seen at earth due to strong circumstellar absorption
at that wavelength. Many new fluorescence line products and several
new processes have been identified in these spectra, which are more
complete and of higher S/N than previously available for these stars.

---------------------------------------------------------
Title: Wide-Field InfrarRed Survey Telescope-Astrophysics Focused
Telescope Assets WFIRST-AFTA 2015 Report
Authors: Spergel, D.; Gehrels, N.; Baltay, C.; Bennett, D.;
Breckinridge, J.; Donahue, M.; Dressler, A.; Gaudi, B. S.; Greene, T.;
Guyon, O.; Hirata, C.; Kalirai, J.; Kasdin, N. J.; Macintosh, B.; Moos,
W.; Perlmutter, S.; Postman, M.; Rauscher, B.; Rhodes, J.; Wang, Y.;
Weinberg, D.; Benford, D.; Hudson, M.; Jeong, W. -S.; Mellier, Y.;
Traub, W.; Yamada, T.; Capak, P.; Colbert, J.; Masters, D.; Penny,
M.; Savransky, D.; Stern, D.; Zimmerman, N.; Barry, R.; Bartusek,
L.; Carpenter, K.; Cheng, E.; Content, D.; Dekens, F.; Demers, R.;
Grady, K.; Jackson, C.; Kuan, G.; Kruk, J.; Melton, M.; Nemati, B.;
Parvin, B.; Poberezhskiy, I.; Peddie, C.; Ruffa, J.; Wallace, J. K.;
Whipple, A.; Wollack, E.; Zhao, F.
2015arXiv150303757S Altcode:
This report describes the 2014 study by the Science Definition Team
(SDT) of the Wide-Field Infrared Survey Telescope (WFIRST) mission. It
is a space observatory that will address the most compelling scientific
problems in dark energy, exoplanets and general astrophysics using a
2.4-m telescope with a wide-field infrared instrument and an optical
coronagraph. The Astro2010 Decadal Survey recommended a Wide Field
Infrared Survey Telescope as its top priority for a new large space
mission. As conceived by the decadal survey, WFIRST would carry out
a dark energy science program, a microlensing program to determine
the demographics of exoplanets, and a general observing program
utilizing its ultra wide field. In October 2012, NASA chartered
a Science Definition Team (SDT) to produce, in collaboration with
the WFIRST Study Office at GSFC and the Program Office at JPL, a
Design Reference Mission (DRM) for an implementation of WFIRST using
one of the 2.4-m, Hubble-quality telescope assemblies recently made
available to NASA. This DRM builds on the work of the earlier WFIRST
SDT, reported by Green et al. (2012) and the previous WFIRST-2.4 DRM,
reported by Spergel et. (2013). The 2.4-m primary mirror enables a
mission with greater sensitivity and higher angular resolution than
the 1.3-m and 1.1-m designs considered previously, increasing both the
science return of the primary surveys and the capabilities of WFIRST
as a Guest Observer facility. The addition of an on-axis coronagraphic
instrument to the baseline design enables imaging and spectroscopic
studies of planets around nearby stars.

---------------------------------------------------------
Title: Comparing Vent Surface Geometry with Its Subsurface Structure
Authors: Parcheta, C.; Parness, A.; Nash, J.; Wiltsie, N.; Carpenter,
K.; Mitchell, K. L.
2015LPI....46.1649P Altcode: 2015LPICo1832.1649P
Magma conduit./Shape is vital yet unknown./How does it erupt?

---------------------------------------------------------
Title: The HST Treasury “Advanced Spectral Library” (ASTRAL)
Programs
Authors: Carpenter, Kenneth G.; Ayres, Thomas R.
2015csss...18.1041C Altcode: 2014arXiv1411.1419C
The “Advanced Spectral Library (ASTRAL)” Project (PI = T. Ayres)
consists of two Treasury Programs: the Cycle 18 “Cool Stars”
(GO-12278) Program and the Cycle 21 “Hot Stars” (GO-13346)
Program. The primary goal of these programs is to collect, for the use
of the astronomical community over the coming decades, a definitive
set of representative, high-resolution (R∼30,000-100,000), high
signal/noise (S/N&gt;100) spectra, with full UV coverage (∼1150 -
3100 Å) of prototypical stars across the HR diagram, utilizing the
high-performance Space Telescope Imaging Spectrograph (STIS). The
Cycle 18 program obtained spectra of 8 F-M evolved late-type
stars, while the Cycle 21 program is in the process of observing
21 early-type stars, which span a broad range of spectral types
between early-O and early-A. All of these data will be available
from the HST archive and, in post-processed and merged form, at
http://casa.colorado.edu/ãyres/ASTRAL/. These data will enable
investigations of a broad range of problems - stellar, interstellar,
and beyond - for many years into the future. We describe here the
details of the observing programs, including the program targets and the
observing strategies utilized to optimize the quality of the spectra,
and present some illustrative examples of the on-going scientific
analyses, including a study of the outer atmospheres and winds of
the two evolved M stars in the sample and a first look at a “high
definition” UV spectrum of a magnetic chemically peculiar “Ap” star.

---------------------------------------------------------
Title: Mining the HST "Advanced Spectral Library (ASTRAL)": Winds
of the Evolved M Stars Alpha Ori (M2 Iab) and Gamma Cru (M3.4 III)
Authors: Carpenter, Kenneth G.; Nielsen, Krister E.; Kober, Gladys V.;
Ayres, Thomas R.
2015AAS...22534408C Altcode:
The "Advanced Spectral Library (ASTRAL) Project: Cool Stars" (PI
= T. Ayres) is an HST Cycle 18 Treasury Program that collected a
definitive set of representative, high-resolution (R=30,000-100,000)
and high signal/noise (S/N&gt;100) UV spectra of eight F-M evolved
cool stars. These extremely high-quality STIS UV echelle spectra are
available from the HST archive and through the ASTRAL website at the
University of Colorado at http://casa.colorado.edu/~ayres/ASTRAL/ and
will enable investigations of a broad range of problems -- stellar,
interstellar, and beyond -- for many years. In this paper, we examine
the wealth of wind diagnostics contained in the very rich spectra
of the two evolved M stars in the sample, the M3.4 III giant Gamma
Crucis (GaCrux) and the M2 Iab supergiant Alpha Orionis (Betelgeuse)
and characterize the winds at the time of these STIS observations in
2011 and compare the results with those obtained from more limited data
taken at earlier epochs with HST/GHRS and IUE. In particular we study
the variation of the numerous Fe II profiles with intrinsic strength
in the two stars. The shifting wavelengths of the wind absorptions
relative to the emission peaks and the changes in relative strengths
of the emission peaks reflect the acceleration of the wind from the
base of the chromosphere. Although the characteristics of the Gamma
Cru wind are relatively stable with time, the Alpha Ori wind outflow
appears significantly smaller than seen by Carpenter et al. (1997,
ApJ, 479, 970) in GHRS observations taken in 1992 (and in earlier IUE
observations). There might in fact be evidence in these STIS spectra
that the outflow has turned into an inflow, as reported at epochs
prior to IUE by Boesgaard and Magnan (1975 ApJ 198, 369) and Boesgaard
(1979 ApJ 232, 485) based on a limited number of lines in the extreme
blue end of ground-based spectra.

---------------------------------------------------------
Title: Toward A Self Consistent MHD Model of Chromospheres and Winds
From Late Type Evolved Stars
Authors: Airapetian, V. S.; Leake, J. E.; Carpenter, Kenneth G.
2015csss...18..269A Altcode: 2014arXiv1409.3833A
We present the first magnetohydrodynamic model of the stellar
chromospheric heating and acceleration of the outer atmospheres
of cool evolved stars, using α Tau as a case study. We used a
1.5D MHD code with a generalized Ohm's law that accounts for the
effects of partial ionization in the stellar atmosphere to study
Alfvén wave dissipation and wave reflection. We have demonstrated
that due to inclusion of the effects of ion-neutral collisions in
magnetized weakly ionized chromospheric plasma on resistivity and
the appropriate grid resolution, the numerical resistivity becomes
1-2 orders of magnitude smaller than the physical resistivity. The
motions introduced by non-linear transverse Alfvé waves can explain
non-thermally broadened and non-Gaussian profiles of optically thin UV
lines forming in the stellar chromosphere of α Tau and other late-type
giant and supergiant stars. The calculated heating rates in the stellar
chromosphere due to resistive (Joule) dissipation of electric currents,
induced by upward propagating non-linear Alfvé waves, are consistent
with observational constraints on the net radiative losses in UV lines
and the continuum from α Tau. At the top of the chromosphere, Alfvé
waves experience significant reflection, producing downward propagating
transverse waves that interact with upward propagating waves and produce
velocity shear in the chromosphere. Our simulations also suggest that
momentum deposition by non-linear Alfvé waves becomes significant in
the outer chromosphere at 1 stellar radius from the photosphere. The
calculated terminal velocity and the mass loss rate are consistent
with the observationally derived wind properties in α Tau.

---------------------------------------------------------
Title: An HST COS "SNAPshot" Spectrum of the K Supergiant λ Vel
(K4Ib-II)
Authors: Carpenter, Kenneth G.; Ayres, Thomas R.; Harper, Graham M.;
Kober, Gladys; Nielsen, Krister E.; Wahlgren, Glenn M.
2014ApJ...794...41C Altcode:
We present a far-ultraviolet spectrum of the K4 Ib-II supergiant λ Vel
obtained with the Hubble Space Telescope's Cosmic Origins Spectrograph
(COS) as a part of the SNAPshot program "SNAPing coronal iron" (GO
11687). The observation covers a wavelength region (1326-1467 Å)
not previously recorded for λ Vel at a spectral resolving power
of R ~ 20,000 and displays strong emission and absorption features,
superposed on a bright chromospheric continuum. Fluorescent excitation
is responsible for much of the observed emission, mainly powered by
strong H I Lyα and the O I (UV 2) triplet emission near λ1304. The
molecular CO and H2 fluorescences are weaker than in the
early-K giant α Boo while the Fe II and Cr II lines, also pumped
by H I Lyα, are stronger in λ Vel. This pattern of relative line
strengths between the two stars is explained by the lower iron-group
element abundance in α Boo, which weakens that star's Fe II and
Cr II emission without reducing the molecular fluorescences. The
λ Vel spectrum shows fluorescent Fe II, Cr II, and H2
emission similar to that observed in the M supergiant α Ori, but
more numerous well-defined narrow emissions from CO. The additional CO
emissions are visible in the spectrum of λ Vel since that star does
not have the cool, opaque circumstellar shells that surround α Ori
and produce broad circumstellar CO (A-X) band absorptions that hide
those emissions in the cooler star. The presence of Si IV emission in
λ Vel indicates a ~8 × 104 K plasma that is mixed into
the cooler chromosphere. Evidence of the stellar wind is seen in the
C II λλ1334,1335 lines and in the blueshifted Fe II and Ni II wind
absorption lines. Line modeling using Sobolev with Exact Integration for
the C II lines indicates a larger terminal velocity (~45 versus ~30 km
s-1) and turbulence (~27 versus &lt;21 km s-1)
with a more quickly accelerating wind (β = 0.35 versus 0.7) at the
time of this COS observation in 2010 than derived from Goddard High
Resolution Spectrograph data obtained in 1994. The Fe II and Ni II
absorptions are blueshifted by 7.6 km s-1 relative to the
chromospheric emission, suggesting formation in lower levels of the
accelerating wind and their widths indicate a higher turbulence in
the λ Vel wind compared to α Ori. Based on observations with
the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

---------------------------------------------------------
Title: Interferometer evolution: imaging terras after building
'little' experiments (INEVITABLE)
Authors: Rinehart, S.; Carpenter, K.; van Belle, G.; Unwin, S.
2014SPIE.9146E..17R Altcode:
Perhaps one of the most ambitious long-term goals of the astronomical
community is to map distant exoplanets. This will require instruments
that provide sufficient angular resolution to place multiple pixels
across an image of an exoplanet. Many other science programs also
require orders of magnitude improvement in angular resolution, and for
all of these, single aperture telescopes are impractical. In fact,
the array of scientific goals that require high angular resolution
makes interferometry inevitable. Here, we discuss some of the long-term
science needs, and the implications for future interferometers, and
then talk about some possible paths towards these future missions.

---------------------------------------------------------
Title: Mining the HST "Advanced Spectral Library (ASTRAL) - Hot
Stars": The High Definition UV Spectrum of the Ap Star HR 465
Authors: Carpenter, Kenneth G.; Ayres, T. R.; Nielsen, K. E.; Kober,
G. V.; Wahlgren, G. M.; Adelman, S. J.; Cowley, C. R.
2014AAS...22315105C Altcode:
The "Advanced Spectral Library (ASTRAL) Project: Hot Stars" is a Hubble
Space Telescope (HST) Cycle 21 Treasury Program (GO-13346: Ayres
PI). It is designed to collect a definitive set of representative,
high-resolution ( 30,000-100,000), high signal/noise (S/N&gt;100),
and full UV coverage 1200 - 3000 A) spectra of 21 early-type stars,
utilizing the high-performance Space Telescope Imaging Spectrograph
(STIS). The targets span the range of spectral types between early-O
and early-A, including both main sequence and evolved stars, fast
and slow rotators, as well as chemically peculiar (CP) and magnetic
objects. These extremely high-quality STIS UV echelle spectra will be
available from the HST archive and, in post-processed and merged form,
at http://casa.colorado.edu ayres/ASTRAL/. The UV "atlases" produced by
this program will enable investigations of a broad range of problems --
stellar, interstellar, and beyond -- for many years to come. We offer a
first look at one of the earliest datasets to come out of this observing
program, a "high definition" UV spectrum of the Ap star HR 465, which
was chosen as a prototypical example of an A-type magnetic CP star. HR
465 has a global magnetic field of ~2200 Gauss. Earlier analyses of IUE
spectra show strong iron-peak element lines, along with heavy elements
such as Ga and Pt, while being deficient in the abundance of some ions
of low atomic number, such as carbon. We demonstrate the high quality
of the ASTRAL data and present the identification of spectral lines
for a number of elements. By comparison of the observed spectra with
calculated spectra, we also provide estimates of element abundances,
emphasizing heavy elements, and place these measurements in the context
of earlier results for this and other Ap stars.

---------------------------------------------------------
Title: Evolution of Stellar Coronae: From the Sun to a Red Giant
Authors: Airapetian, Vladimir; Leake, J. E.; Carpenter, K. G.
2014AAS...22342401A Altcode:
All stars in the H-R diagram later than spectral class F5 possess a
convective zone that provides a reservoir of mechanical energy to drive
activity in layers above the photosphere and to shape its atmospheric
structures. Cool stars on the main sequence are characterized by compact
chromospheres/transition regions and extended coronae transitioning into
stellar winds. As the star exhausts its hydrogen fuel and enters into a
giant/supergiant phase of its life, its atmospheric structures change
dramatically showing signatures of bloated chromospheres and compact
coronae. What physical mechanisms are responsible for such a drastic
transition from a "dwarf" chromosphere of a cool dwarf star into a
"giant" chromosphere of an evolved giant? How does a "giant" corona of a
dwarf star evolve into a "dwarf" corona" of a giant star? In this talk
we present a unified picture of the evolution of stellar atmospheric
structures as a cool stars moves from the main-sequence to a red giant
phase. The results of our 2.5D magnetohydrodynamic (MHD) simulations
suggest the dynamics of the emergence of magnetic flux into the
atmospheres of cool stars is strongly dependent on surface gravity and
the magnetic field. We simulate the dynamics of emergence of magnetic
field in the Sun, a sug-giant and a giant star. Our simulations suggest
that as the surface gravity becomes smaller and the magnetic field
weaker as the star evolves, the magnetic flux cannot be transported
high enough into the atmosphere to form an extended corona. Instead,
it forms highly compact loops in the lower layers of bloated stellar
chromospheres and heated by Alfven waves to coronal temperatures.

---------------------------------------------------------
Title: Using ISS telescopes for electromagnetic follow-up of
gravitational wave detections of NS-NS and NS-BH mergers
Authors: Camp, J.; Barthelmy, S.; Blackburn, L.; Carpenter, K. G.;
Gehrels, N.; Kanner, J.; Marshall, F. E.; Racusin, J. L.; Sakamoto, T.
2013ExA....36..505C Altcode: 2013arXiv1304.3705C; 2013ExA...tmp...31C
The International Space Station offers a unique platform for rapid and
inexpensive deployment of space telescopes. A scientific opportunity
of great potential later this decade is the use of telescopes for the
electromagnetic follow-up of ground-based gravitational wave detections
of neutron star and black hole mergers. We describe this possibility
for OpTIIX, an ISS technology demonstration of a 1.5 m diffraction
limited optical telescope assembled in space, and ISS-Lobster, a
wide-field imaging X-ray telescope now under study as a potential
NASA mission. Both telescopes will be mounted on pointing platforms,
allowing rapid positioning to the source of a gravitational wave
event. Electromagnetic follow-up rates of several per year appear
likely, offering a wealth of complementary science on the mergers of
black holes and neutron stars.

---------------------------------------------------------
Title: Sorptive fractionation of organic matter and formation of
organo-hydroxy-aluminum complexes during litter biodegradation in
the presence of gibbsite
Authors: Heckman, K.; Grandy, A. S.; Gao, X.; Keiluweit, M.; Wickings,
K.; Carpenter, K.; Chorover, J.; Rasmussen, C.
2013GeCoA.121..667H Altcode:
Solid and aqueous phase Al species are recognized to affect organic
matter (OM) stabilization in forest soils. However, little is known
about the dynamics of formation, composition and dissolution of
organo-Al hydroxide complexes in microbially-active soil systems, where
plant litter is subject to microbial decomposition in close proximity
to mineral weathering reactions. We incubated gibbsite-quartz mineral
mixtures in the presence of forest floor material inoculated with
a native microbial consortium for periods of 5, 60 and 154 days. At
each time step, samples were density separated into light (&lt;1.6
g cm-3), intermediate (1.6-2.0 g cm-3), and
heavy (&gt;2.0 g cm-3) fractions. The light fraction was
mainly comprised of particulate organic matter, while the intermediate
and heavy density fractions contained moderate and large amounts of
Al-minerals, respectively. Multi-method interrogation of the fractions
indicated the intermediate and heavy fractions differed both in mineral
structure and organic compound composition. X-ray diffraction analysis
and SEM/EDS of the mineral component of the intermediate fractions
indicated some alteration of the original gibbsite structure into
less crystalline Al hydroxide and possibly proto-imogolite species,
whereas alteration of the gibbsite structure was not evident in the
heavy fraction. DRIFT, Py-GC/MS and STXM/NEXAFS results all showed that
intermediate fractions were composed mostly of lignin-derived compounds,
phenolics, and polysaccharides. Heavy fraction organics were dominated
by polysaccharides, and were enriched in proteins, N-bearing compounds,
and lipids. The source of organics appeared to differ between the
intermediate and heavy fractions. Heavy fractions were enriched
in 13C with lower C/N ratios relative to intermediate
fractions, suggesting a microbial origin. The observed differential
fractionation of organics among hydroxy-Al mineral types suggests that
microbial activity superimposed with abiotic mineral-surface-mediated
fractionation leads to strong density differentiation of organo-mineral
complex composition even over the short time scales probed in these
incubation experiments. The data highlight the strong interdependency
of mineral transformation, microbial community activity, and organic
matter stabilization during biodegradation.

---------------------------------------------------------
Title: Tracing Magnetic "Active Regions" in Non-Coronal and Hybrid
Cool Giants
Authors: Airapetian, Vladimir; Carpenter, K. G.
2013giec.conf10305A Altcode:
FUSE and HST/STIS and GHRS observations of a number of non-coronal
and hybrid giants reveal dynamics processes in their atmospheres. The
observed variations in the fluxes, non-thermal broadening, and shifts of
selected UV chromospheric emission lines provide a powerful diagnostic
tool to characterize the total unsigned magnetic flux and its rotational
modulation in cool giant stars, as well as the energy dissipation and
momentum deposition in their atmospheres. We utilize a new empirical
method, based on our numerical model of Alfvén wave-driven winds
from evolved stars, to detect and characterize the signatures of the
rotational modulation of magnetic "active regions" in two evolved
giant stars, representative of both hybrid and non-coronal (K5 III)
stars. Specifically, we derive the properties of chromospheric motions
and heating rates at two or more epochs for each star. We use archival
FUSE, HST/GHRS and HST/STIS observations to address a fundamental
question in the evolution of magnetic dynamos in late-type giant stars,
namely: what is the inter-relationship between chromospheric turbulence,
magnetic flux, and the wind properties in cool, evolved stars?

---------------------------------------------------------
Title: The Role of Alfvén Waves in Atmospheric Dynamics of
Non-Coronal, Hybrid and Coronal Giants
Authors: Airapetian, Vladimir; Carpenter, K. G.; Evans, R. M.
2013giec.conf30102A Altcode:
In this talk, we discuss the properties of atmospheric heating and
wind dynamics from non-coronal, hybrid and coronal giants described by
an Alfvén-wave driven model of stellar atmospheres. Specifically, we
present the results of numerical simulations of winds from non-coronal
and hybrid evolved giant stars using a fully nonlinear, time-dependent
2.5-dimensional magnetohydrodynamic (MHD) code. This study extends our
previous fully nonlinear MHD wind simulations to include a broadband
frequency spectrum of Alfvén waves that drive winds from red giant
stars. We discuss four Alfven wind models that cover the whole range of
the Alfvén wave frequency spectrum to characterize the role of freely
propagated and reflected Alfvén waves in the gravitationally stratified
atmosphere of a late-type giant star. Our simulations demonstrate that,
unlike linear Alfvén wave-driven wind models, a stellar wind model
based on plasma acceleration due to broadband non-linear Alfvén waves
can consistently reproduce the wide range of radial velocity profiles
of the winds, their terminal velocities, and the observed mass loss
rates observed in non-coronal and hybrid giants. We also present the
recent results of simulations of the thermodynamics and dynamics of
the atmosphere of a magnetically active coronal giant, β Ceti, by
applying a 3D MHD code, BATRUS, that incorporates a self-consistent
treatment of energy dissipation due Alfvén wave turbulence, thermal
conduction and radiative cooling terms.

---------------------------------------------------------
Title: Signatures of Rotational Modulation of Magnetic "Active
Regions" in Hybrid and Non-coronal Cool Giant Stars
Authors: Carpenter, Kenneth G.; Airapetian, V.
2013AAS...22211614C Altcode:
Observations of the variations in the fluxes, non-thermal broadening,
and shifts of selected UV chromospheric emission lines provide a
powerful diagnostic tool to characterize the total unsigned magnetic
flux and its rotational modulation in cool giant stars, as well as the
energy dissipation and momentum deposition in their atmospheres. We
utilize a new empirical method, based on our 2.5D MHD model of Alfvén
wave-driven winds from evolved stars, to detect and characterize the
signatures of the rotational modulation of magnetic "active regions" in
two evolved giant stars, representative of both hybrid and non-coronal
(K5 III) stars. Specifically, we derive the properties of chromospheric
motions and heating rates at two or more epochs for each star. We use
archival HST/GHRS and HST/STIS observations to address a fundamental
question in the evolution of magnetic dynamos in late-type giant stars,
namely: what is the inter-relationship between chromospheric turbulence,
magnetic flux, and the wind properties in cool, evolved stars?

---------------------------------------------------------
Title: Mining the Advanced Spectral Library (ASTRAL): Characterizing
Winds of Evolved M-Stars
Authors: Nielsen, Krister E.; Carpenter, K. G.; Kober, G. V.; Cheng,
K.; Ayres, T. R.; Harper, G.
2013AAS...22135102N Altcode:
The HST/STIS treasury program Advanced Spectral Library (ASTRAL)
enables investigations of the character and dynamics of the wind and
chromosphere of cool stars, using high quality spectral data. This
paper present the analysis of the outflowing winds of the M3.4 giant
Gamma Cru and the M2Iab supergiant Alpha Ori. The outer atmospheres
of these objects show strong evidence for significant inhomogeneity
in their thermal and kinematic structure, and are in general not
well understood. The wind features are characterized by a strong
chromospheric emission suppressed by a overlying wind absorption,
for many transitions producing a double peak feature. The relative
strengths and wavelength shifts between the absorption and emission
components of the lines reflect the acceleration of the wind from the
base of the chromosphere, as the self-absorption is due to the overlying
wind absorption, whose velocity relative to the chromosphere varies
with height and thus line opacity. The wind profiles are sensitive to
the wind opacity, turbulence and flow velocity, and hence favorable
to analyze with the Sobolev source function with Exact Integration of
the transfer equation (SEI) code. This paper will show a velocity and
intensity analysis of the wind profiles and modeling with the SEI code
to derive an improved set of wind parameters, primarily, for Gamma Cru.

---------------------------------------------------------
Title: Mining the Advanced Spectral Library (ASTRAL): Fluorescence
in Evolved M-Stars
Authors: Carpenter, Kenneth G.; Nielsen, K. E.; Kober, G. V.; Cheng,
K.; Ayres, T. R.; Wahlgren, G. M.; Harper, G.
2013AAS...22135101C Altcode:
The "Advanced Spectral Library (ASTRAL) Project: Cool Stars" (PI =
T. Ayres) is an HST Cycle 18 Treasury Program designed to collect
a definitive set of representative, high-resolution ( 46,000 in the
FUV up to ~1700 Å, 30,000 for 1700-2150 Å, and 114,000 &gt;2150 Å)
and high signal/noise (S/N&gt;100) UV spectra of eight F-M evolved
cool stars. These extremely high-quality STIS UV echelle spectra are
available from the HST archive and through the University of Colorado
(http://casa.colorado.edu ayres/ASTRAL/) and will enable investigations
of a broad range of problems -- stellar, interstellar, and beyond -- for
many years. In this paper, we use the very rich emission-line spectra
of the two evolved M stars in the sample, the M3.4 giant Gamma Crucis
(GaCrux) and the M2Iab supergiant Alpha Orionis (Betelgeuse), to study
the fluorescence processes operating in their outer atmospheres. We
summarize the pumping transitions and fluorescent line products known
on the basis of previous work (e.g. Carpenter 1988 and references
therein) and newly identified in our current, on-going analysis and
provide some comments on their implications for the structure of the
outer atmospheres of these stars.

---------------------------------------------------------
Title: Using the ISS as a testbed to prepare for the next generation
of space-based telescopes
Authors: Postman, Marc; Sparks, William B.; Liu, Fengchuan; Ess, Kim;
Green, Joseph; Carpenter, Kenneth G.; Thronson, Harley; Goullioud,
Renaud
2012SPIE.8442E..1TP Altcode:
The infrastructure available on the ISS provides a unique opportunity
to develop the technologies necessary to assemble large space
telescopes. Assembling telescopes in space is a game-changing approach
to space astronomy. Using the ISS as a testbed enables a concentration
of resources on reducing the technical risks associated with integrating
the technologies, such as laser metrology and wavefront sensing and
control (WFS&amp;C), with the robotic assembly of major components
including very light-weight primary and secondary mirrors and the
alignment of the optical elements to a diffraction-limited optical
system in space. The capability to assemble the optical system and
remove and replace components via the existing ISS robotic systems
such as the Special Purpose Dexterous Manipulator (SPDM), or by the
ISS Flight Crew, allows for future experimentation as well as repair if
necessary. In 2015, first light will be obtained by the Optical Testbed
and Integration on ISS eXperiment (OpTIIX), a small 1.5-meter optical
telescope assembled on the ISS. The primary objectives of OpTIIX include
demonstrating telescope assembly technologies and end-to-end optical
system technologies that will advance future large optical telescopes.

---------------------------------------------------------
Title: Harnessing the Power of NASA's Kepler Mission for Understanding
Stellar Activity and Enhancing Planet Discovery
Authors: Bastien, Fabienne A.; Stassun, K. G.; Pepper, J.; Walkowicz,
L.; Basri, G.; Carpenter, K. G.
2012AAS...21934504B Altcode:
The magnetic activity of stars, which often manifests itself in the
form of starspots, can induce short-timescale photometric variability,
thereby adding to the difficulty of detecting planets, particularly
those in the Earth mass range. Indeed, photometric "noise” caused
by stellar magnetic activity can preclude the detection of the tiny
transit signature that a planet like ours would produce. Hence, in order
to successfully detect Earth-like planets via the transit method, the
exoplanet community needs a way characterize the photometric stability
of a star in advance. The goal of our project is to empirically relate
chromospheric activity and photometric variability for a large sample
of stars, spanning a range of stellar masses and evolutionary states,
in order to develop an index that is predictive of stellar photometric
variability. The inclusion of stars with a range of known rotation
periods, as well as subgiants, giants, and Kepler asteroseismology
targets, will allow us to more finely examine the relationship
between a star's age and its magnetic activity. This work will aid
in a fundamental understanding of the physics of magnetic activity
in solar-type stars. We acknowledge support through NSF PAARE grant
AST-0849736.

---------------------------------------------------------
Title: The Amazing COS FUV (1320 - 1460 Å) Spectrum of λ Vel
(K4Ib-II)1
Authors: Carpenter, K. G.; Ayres, T.; Brown, A.; Harper, G. M.;
Wahlgren, G. M.
2011ASPC..448.1083C Altcode: 2011csss...16.1083C
The FUV spectrum (1320-1460 Å) of the K4 Ib-II supergiant λ Vel
was observed with the Cosmic Origins Spectrograph (COS) on HST, as
part of the Ayres and Redfield Cycle 17 SNAP program "SNAPing Coronal
Iron." This spectrum covers a region not previously recorded in λ
Vel at high resolution and, in a mere 20 minutes of exposure, reveals
an amazing treasure trove of information. It shows a wide variety of
strong emission lines and multiple absorption lines, superposed on a
bright chromospheric continuum, with contributions from both atomic
and molecular species. These features provide diagnostics of the
chromosphere and wind of the star, and by comparison with spectra of
stars of similar Teff and/or geff, will improve
our knowledge of the heating processes in the chromospheres and the
forces driving the stellar wind in cool evolved stars. We present
the details of this spectrum, in comparison with stars of similar
temperature or luminosity, and discuss our initial interpretation of
the data.

---------------------------------------------------------
Title: The Stellar Imager (SI) - A Mission to Resolve Stellar
Surfaces, Interiors, and Magnetic Activity
Authors: Christensen-Dalsgaard, Jørgen; Carpenter, Kenneth G.;
Schrijver, Carolus J.; Karovska, Margarita; Si Team
2011JPhCS.271a2085C Altcode:
The Stellar Imager (SI) is a space-based, UV/Optical Interferometer
(UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging
of stellar surfaces and of the Universe in general. It will also probe
via asteroseismology flows and structures in stellar interiors. SI
will enable the development and testing of a predictive dynamo model
for the Sun, by observing patterns of surface activity and imaging
of the structure and differential rotation of stellar interiors in
a population study of Sun-like stars to determine the dependence of
dynamo action on mass, internal structure and flows, and time. SI's
science focuses on the role of magnetism in the Universe and will
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes in the Universe. SI
is a "Landmark/Discovery Mission" in the 2005 Heliophysics Roadmap,
an implementation of the UVOI in the 2006 Astrophysics Strategic Plan,
and a NASA Vision Mission ("NASA Space Science Vision Missions" (2008),
ed. M. Allen). We present here the science goals of the SI Mission,
a mission architecture that could meet those goals, and the technology
development needed to enable this mission. Additional information on
SI can be found at: http://hires.gsfc.nasa.gov/si/.

---------------------------------------------------------
Title: λ Vel (K4 Ib-II): Fluorescence on a PAR with Other Luminaries
Authors: Wahlgren, G. M.; Carpenter, K. G.; Ayres, T. R.; Brown, A.;
Harper, G. M.
2011AAS...21715406W Altcode: 2011BAAS...4315406W
The ultraviolet spectral region of cool, luminous stars contains
emission features that originate from fluorescent mechanisms via PAR
(photo-excitation by accidental resonance). These mechanisms can account
for numerous emission lines, downward transitions from upper energy
levels pumped by strong transitions, such as H Ly-α, O I 1302, C II
1335, and Mg II h&amp;k. A new, high S/N observation of the cool giant
star λ Vel (K4 Ib-II) was obtained with the HST/COS instrument at a
resolving power of R 20000 and covers the wavelength region from 132 nm
to 147 nm. High-quality spectra (COS and GHRS) are now available from
128 nm to 147 nm, and at 12 moderate and high resolution observations
from the HST/GHRS, the latter covering approximately a third of the
wavelength interval from 189 nm to 285 nm. Using these data, together
with observations from FUSE and IUE, we investigate PAR processes in the
spectra of Cr II and Fe II and make comparisons with other stars. The
presence of additional atomic (O I, S I, and Cl I) and molecular (H2,
CO) PAR processes in the spectrum of λ Vel is briefly discussed.

---------------------------------------------------------
Title: The Chromospheric Structure and Wind of the K-Supergiant
Lambda Velorum
Authors: Carpenter, Kenneth G.; Ayres, T. R.; Brown, A.; Harper,
G. M.; Wahlgren, G. M.
2011AAS...21715407C Altcode: 2011BAAS...4315407C
Recently, the 1326-1466 Å region of the FUV spectrum of the K4 Ib-II
supergiant Lambda Vel was observed with the Cosmic Origins Spectrograph
(COS) on HST, as part of the Ayres and Redfield Cycle 17 SNAP program
"SNAPing Coronal Iron.” This spectrum covers a region not previously
recorded in Lambda Vel at high resolution and, in a mere 20 minutes
of exposure, reveals an amazing treasure trove of information. It
shows a wide variety of strong atomic and molecular emission lines
formed in the chromosphere and multiple atomic absorption lines
formed in the stellar wind, both superposed on a bright chromospheric
continuum. Further evidence of the stellar wind is seen in the P Cygni
profiles presented by the C II (UV 1) lines near 1335 Å. We combine
this COS data with archival GHRS spectra of other selected FUV and NUV
regions to better characterize the outer atmospheric structure of the
star and its massive, outflowing wind.

---------------------------------------------------------
Title: Winds from Luminous Late-type Stars. II. Broadband Frequency
Distribution of Alfvén Waves
Authors: Airapetian, V.; Carpenter, K. G.; Ofman, L.
2010ApJ...723.1210A Altcode: 2010arXiv1008.3955A
We present the numerical simulations of winds from evolved giant
stars using a fully nonlinear, time-dependent 2.5-dimensional
magnetohydrodynamic (MHD) code. This study extends our previous fully
nonlinear MHD wind simulations to include a broadband frequency spectrum
of Alfvén waves that drive winds from red giant stars. We calculated
four Alfvén wind models that cover the whole range of the Alfvén wave
frequency spectrum to characterize the role of freely propagated and
reflected Alfvén waves in the gravitationally stratified atmosphere
of a late-type giant star. Our simulations demonstrate that, unlike
linear Alfvén wave-driven wind models, a stellar wind model based
on plasma acceleration due to broadband nonlinear Alfvén waves can
consistently reproduce the wide range of observed radial velocity
profiles of the winds, their terminal velocities, and the observed
mass-loss rates. Comparison of the calculated mass-loss rates with the
empirically determined mass-loss rate for α Tau suggests an anisotropic
and time-dependent nature of stellar winds from evolved giants.

---------------------------------------------------------
Title: Stellar Imager (SI): developing and testing a predictive
dynamo model for the Sun by imaging other stars
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska,
Margarita; Kraemer, Steve; Lyon, Richard; Mozurkewich, David;
Airapetian, Vladimir; Adams, John C.; Allen, Ronald J.; Brown, Alex;
Bruhweiler, Fred; Conti, Alberto; Christensen-Dalsgaard, Joergen;
Cranmer, Steve; Cuntz, Manfred; Danchi, William; Dupree, Andrea; Elvis,
Martin; Evans, Nancy; Giampapa, Mark; Harper, Graham; Hartman, Kathy;
Labeyrie, Antoine; Leitner, Jesse; Lillie, Chuck; Linsky, Jeffrey L.;
Lo, Amy; Mighell, Ken; Miller, David; Noecker, Charlie; Parrish, Joe;
Phillips, Jim; Rimmele, Thomas; Saar, Steve; Sasselov, Dimitar; Stahl,
H. Philip; Stoneking, Eric; Strassmeier, Klaus; Walter, Frederick;
Windhorst, Rogier; Woodgate, Bruce; Woodruff, Robert
2010arXiv1011.5214C Altcode:
The Stellar Imager mission concept is a space-based UV/Optical
interferometer designed to resolve surface magnetic activity and
subsurface structure and flows of a population of Sun-like stars,
in order to accelerate the development and validation of a predictive
dynamo model for the Sun and enable accurate long-term forecasting of
solar/stellar magnetic activity.

---------------------------------------------------------
Title: Commission 29: Stellar Spectra
Authors: Piskunov, Nikolai; Cunha, Katia; Parthasarathy, Mudumba;
Aoki, Wako; Asplund, Martin; Bohlender, David; Carpenter, Kenneth;
Melendez, Jorge; Parthasarathy, Mudumba; Rossi, Silvia; Smith, Verne;
Soderblom, David; Wahlgren, Glenn
2010IAUTB..27..193P Altcode:
The business meeting was attended by 23 members of the Commission. The
meeting started at 16:00 a short report of the activities during the
triennium 2006-2009. The focus of the activities was the sharing
of expertise between spectroscopic techniques in various areas of
astronomical research. In particular, the progress in instrumentation,
detectors, data reduction, data analysis and archiving. The second
activity was the analysis of to IAU meeting proposals followed by
recommendations for improvements and eventually support. The sponsored
symposia included Sponsoring symposia The Ages of Stars and The Disk
Galaxy Evolution in the Cosmological Context. The Commission was also
disseminating information about the Commission activities and relevant
meetings to the Commission members. In this respect the Commission
web page is playing a crucial role.

---------------------------------------------------------
Title: 2.5d Mhd Simulations Of Winds From Red Giants Stars: Broadband
Alfvén Waves
Authors: Airapetian, Vladimir; Carpenter, K.; Ofman, L.
2010AAS...21542703A Altcode: 2010BAAS...42..342A
We present the numerical simulations of winds from evolved giant
stars using a fully non-linear, time dependent, 2.5-dimensional
magnetohydrodynamic (MHD) code. This study extends our previous
fully non-linear MHD wind simulations to the parameter space that
describes winds from red giant stars. In the current version of this
Alfvén wave driven model, a wind is driven by randomly generated
low-frequency non-linear Alfvén waves in a broadband frequency
range at the base of the wind. We simulate freely propagated and
partially reflected Alfvén waves in the gravitationally stratified
atmosphere of a late-type giant star, in a self-consistent manner,
until a steady-state wind is formed. Our simulations demonstrate
that, unlike linear Alfven wave-driven wind models, a stellar wind
model based on plasma acceleration due to low frequency broad-band
non-linear Alfvén waves, can consistently reproduce the observed radial
velocity profiles of the winds, their terminal velocities, the turbulent
broadening of UV lines emitted from those winds and the observed mass
loss rates. We find that conversion of non-linear transverse Alfvén
waves into longitudinal magnetosonic waves plays the major role in
depositing momentum and energy into the stellar wind. The fitting of
mass-loss rates from α Tau with the predicted rate suggests a highly
anisotropic stellar wind in this evolved giant. The model also predicts
a variation of the wind mass-loss rates on time scales of 1 month.

---------------------------------------------------------
Title: The Stellar Commodity Market: Cu, Ag, And Au In The Sun And
Solar-type Stars
Authors: Wahlgren, Glenn Michael; Carpenter, K. G.; Nave, G.
2010AAS...21542705W Altcode: 2010BAAS...42..343W
The elements copper, silver and gold occupy the same column of the
periodic table and share the property that their only stable isotopes
are odd-numbered, which implies a need for hyperfine structure data when
analyzing their spectral lines. A comparison of their solar photospheric
abundances with the standard meteoritic element abundances shows that
for two of them (Ag, Au) the differences are as large as or larger than
the sum of the uncertainties. With some exceptions, the study of the
chemical composition of most stars stops at the end of the iron group of
elements. Heavier elements are typically not analyzed, often due to the
lack of accurate atomic line data. While the post iron-group elements
make a small contribution to the total abundance one can argue that,
for many reasons, life on earth would not be the same without copper,
silver and gold. We first revisit the abundances of these elements
in the solar photosphere, accounting for the revisions in atomic
data since these elements were last analyzed in the photosphere. The
hyperfine structure of Cu I and Ag I is included in our synthetic
spectrum calculations. The spectra Cu I and Cu II are of current
interest to us for the determination of hfs constants based on our
new laboratory Fourier transform spectrometer data. We then determine
the abundances for these elements in the high-resolution spectra
for a sample of solar-like stars, obtained from on-line data bases,
using synthetic spectrum techniques. The analysis aims to determine the
abundance dispersion of these elements in solar-like stars in the solar
neighborhood. Some of these stars are known to possess exo-planets,
and the abundances of these elements will be correlated with host star
metallicity. In general, we aim to encourage a more extensive use of
the periodic table for stellar astrophysics.

---------------------------------------------------------
Title: The Stellar Imager (SI) - A Mission to Resolve Stellar
Surfaces, Interiors, and Magnetic Activity
Authors: Carpenter, K. G.; Schrijver, C. J.; Karovska, M.; Si Vision
Mission Team
2009ASPC..412...91C Altcode:
The Stellar Imager (SI) is a UV/Optical, Space-Based Interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of
stellar surfaces and, via asteroseismology, stellar interiors and of
the Universe in general. The ultra-sharp images of the Stellar Imager
will revolutionize our view of many dynamic astrophysical processes
by transforming point sources into extended sources, and snapshots
into evolving views. SI's science focuses on the role of magnetism
in the Universe, particularly on magnetic activity on the surfaces of
stars like the Sun. SI's prime goal is to enable long-term forecasting
of solar activity and the space weather that it drives. SI will also
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes in the Universe. SI is
included as a “Flagship and Landmark Discovery Mission” in the 2005
NASA Sun Solar System Connection (SSSC) Roadmap and as a candidate
for a “Pathways to Life Observatory” in the NASA Exploration of the
Universe Division (EUD) Roadmap (May, 2005). In this paper we discuss
the science goals and technology needs of, and the baseline design
for, the SI Mission (http://hires.gsfc.nasa.gov/si/) and its ability
to image the Biggest, Baddest, Coolest Stars.

---------------------------------------------------------
Title: Balloon exoplanet nulling interferometer (BENI)
Authors: Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.;
Vasudevan, Gopal; Ford, Holland; Petro, Larry; Herman, Jay; Rinehart,
Stephen; Carpenter, Kenneth; Marzouk, Joe
2009SPIE.7440E..1AL Altcode: 2009SPIE.7440E..38L
We evaluate the feasibility of a balloon-borne nulling interferometer to
detect and characterize an exosolar planet and the surrounding debris
disk. The existing instrument consists of a three-telescope Fizeau
imaging interferometer with thre fast steering mirrors and three delay
lines operating at 800 Hz for closed-loop control of wavefront errors
and fine pointing. A compact visible nulling interferometer would be
coupled to the imaging interferometer and in principle, allows deep
starlight suppression. Atmospheric simulations of the environment
above 100,000 feet show that balloonborne payloads are a possible
path towards the direct detection and characterization of a limited
set of exoplanets and debris disks. Furthermore, rapid development
of lower cost balloon payloads provide a path towards advancement
of NASA technology readiness levels for future space-based exoplanet
missions. Discussed are the BENI mission and instrument, the balloon
environment and the feasibility of such a balloon-borne mission.

---------------------------------------------------------
Title: Stellar imager (SI): enhancements to the mission enabled by
the constellation architecture (Ares I/Ares V)
Authors: Carpenter, Kenneth G.; Karovska, Margarita; Lyon, Richard G.;
Mozurkewich, D.; Schrijver, Carolus
2009SPIE.7436E..0AC Altcode: 2009SPIE.7436E...9C
Stellar Imager (SI) is a space-based, UV/Optical Interferometer (UVOI)
with over 200x the resolution of HST. It will enable 0.1 milli-arcsec
spectral imaging of stellar surfaces and the Universe in general
and open an enormous new "discovery space" for astrophysics with its
combination of high angular resolution, dynamic imaging, and spectral
energy resolution. SI's goal is to study the role of magnetism in
the Universe and revolutionize our understanding of: 1) Solar/Stellar
Magnetic Activity and their impact on Space Weather, Planetary Climates,
and Life, 2) Magnetic and Accretion Processes and their roles in the
Origin &amp; Evolution of Structure and in the Transport of Matter
throughout the Universe, 3) the close-in structure of Active Galactic
Nuclei and their winds, and 4) Exo-Solar Planet Transits and Disks. SI
is a "Landmark/Discovery Mission" in 2005 Heliophysics Roadmap and a
candidate UVOI in the 2006 Astrophysics Strategic Plan and is targeted
for launch in the mid-2020's. It is a NASA Vision Mission and has
been recommended for further study in a 2008 NRC report on missions
potentially enabled/enhanced by an Ares V launch. In this paper,
we discuss the science goals and required capabilities of SI, the
baseline architecture of the mission assuming launch on one or more
Delta rockets, and then the potential significant enhancements to the
SI science and mission architecture that would be made possible by a
launch in the larger volume Ares V payload fairing, and by servicing
options under consideration in the Constellation program.

---------------------------------------------------------
Title: Transient Processes in the Atmosphere of α Tau
Authors: Airapetian, V.; Carpenter, K. G.; Ake, T.
2009AIPC.1135..215A Altcode:
Far Ultraviolet Spectrograph Explorer (FUSE) spectra of UV emission
lines observed in α Tau at two epochs separated by four months show
dramatic differences in emission line fluxes and line shifts. This
presents the first evidence of dynamic plasma heating in the active
region of this cool giant star. We discuss these observations in terms
of Alfven wave heating in magnetic loops.

---------------------------------------------------------
Title: The Stellar Imager (SI) project: a deep space UV/Optical
Interferometer (UVOI) to observe the Universe at 0.1 milli-arcsec
angular resolution
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska,
Margarita
2009Ap&SS.320..217C Altcode: 2008Ap&SS.tmp...99C
The Stellar Imager (SI) is a space-based, UV/Optical Interferometer
(UVOI) designed to enable 0.1 milli-arcsecond (mas) spectral imaging
of stellar surfaces and of the Universe in general. It will also probe
via asteroseismology flows and structures in stellar interiors. SI’s
science focuses on the role of magnetism in the Universe and will
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes, such as accretion, in
the Universe. The ultra-sharp images of SI will revolutionize our view
of many dynamic astrophysical processes by transforming point sources
into extended sources, and snapshots into evolving views. SI is a
“Flagship and Landmark Discovery Mission” in the 2005 Heliophysics
Roadmap and a potential implementation of the UVOI in the 2006 Science
Program for NASA’s Astronomy and Physics Division. We present here
the science goals of the SI Mission, a mission architecture that
could meet those goals, and the technology development needed to
enable this mission. Additional information on SI can be found at:
http://hires.gsfc.nasa.gov/si/

---------------------------------------------------------
Title: Technology Development for Future Sparse Aperture Telescopes
and Interferometers in Space
Authors: Carpenter, Kenneth G.; Gendreau, Keith; Leitner, Jesse; Lyon,
Richard; Stoneking, Eric; Stahl, H. Philip; Parrish, Joe; Schrijver,
Carolus J.; Woodruff, Robert; Lillie, Chuck; Lo, Amy; Mozurkewich,
David; Labeyrie, Antoine; Miller, David; Mighell, Ken; Karovska,
Margarita; Phillips, James; Allen, Ronald J.; Cash, Webster
2009astro2010T..47C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Luciola hypertelescope space observatory: versatile, upgradable
high-resolution imaging, from stars to deep-field cosmology
Authors: Labeyrie, Antoine; Le Coroller, Hervé; Dejonghe, Julien;
Lardière, Olivier; Aime, Claude; Dohlen, Kjetil; Mourard, Denis;
Lyon, Richard; Carpenter, Kenneth G.
2009ExA....23..463L Altcode: 2008ExA...tmp...48L
Luciola is a large (1 km) “multi-aperture densified-pupil imaging
interferometer”, or “hypertelescope” employing many small
apertures, rather than a few large ones, for obtaining direct snapshot
images with a high information content. A diluted collector mirror,
deployed in space as a flotilla of small mirrors, focuses a sky image
which is exploited by several beam-combiner spaceships. Each contains a
“pupil densifier” micro-lens array to avoid the diffractive spread
and image attenuation caused by the small sub-apertures. The elucidation
of hypertelescope imaging properties during the last decade has shown
that many small apertures tend to be far more efficient, regarding the
science yield, than a few large ones providing a comparable collecting
area. For similar underlying physical reasons, radio-astronomy has
also evolved in the direction of many-antenna systems such as the
proposed Low Frequency Array having “hundreds of thousands of
individual receivers”. With its high limiting magnitude, reaching
the m v = 30 limit of HST when 100 collectors of 25 cm will
match its collecting area, high-resolution direct imaging in multiple
channels, broad spectral coverage from the 1,200 Å ultra-violet to
the 20 μm infra-red, apodization, coronagraphic and spectroscopic
capabilities, the proposed hypertelescope observatory addresses very
broad and innovative science covering different areas of ESA’s Cosmic
Vision program. In the initial phase, a focal spacecraft covering
the UV to near IR spectral range of EMCCD photon-counting cameras
(currently 200 to 1,000 nm), will image details on the surface of
many stars, as well as their environment, including multiple stars
and clusters. Spectra will be obtained for each resel. It will also
image neutron star, black-hole and micro-quasar candidates, as well as
active galactic nuclei, quasars, gravitational lenses, and other Cosmic
Vision targets observable with the initial modest crowding limit. With
subsequent upgrade missions, the spectral coverage can be extended
from 120 nm to 20 μm, using four detectors carried by two to four
focal spacecraft. The number of collector mirrors in the flotilla can
also be increased from 12 to 100 and possibly 1,000. The imaging and
spectroscopy of habitable exoplanets in the mid infra-red then becomes
feasible once the collecting area reaches 6 m2, using a
specialized mid infra-red focal spacecraft. Calculations (Boccaletti
et al., Icarus 145, 628-636, 2000) have shown that hypertelescope
coronagraphy has unequalled sensitivity for detecting, at mid infra-red
wavelengths, faint exoplanets within the exo-zodiacal glare. Later
upgrades will enable the more difficult imaging and spectroscopy of
these faint objects at visible wavelengths, using refined techniques
of adaptive coronagraphy (Labeyrie and Le Coroller 2004). Together,
the infra-red and visible spectral data carry rich information on
the possible presence of life. The close environment of the central
black-hole in the Milky Way will be imageable with unprecedented detail
in the near infra-red. Cosmological imaging of remote galaxies at the
limit of the known universe is also expected, from the ultra-violet
to the near infra-red, following the first upgrade, and with greatly
increasing sensitivity through successive upgrades. These areas will
indeed greatly benefit from the upgrades, in terms of dynamic range,
limiting complexity of the objects to be imaged, size of the elementary
“Direct Imaging Field”, and limiting magnitude, approaching
that of an 8-m space telescope when 1,000 apertures of 25 cm are
installed. Similar gains will occur for addressing fundamental problems
in physics and cosmology, particularly when observing neutron stars
and black holes, single or binary, including the giant black holes,
with accretion disks and jets, in active galactic nuclei beyond the
Milky Way. Gravitational lensing and micro-lensing patterns, including
time-variable patterns and perhaps millisecond lensing flashes which may
be beamed by diffraction from sub-stellar masses at sub-parsec distances
(Labeyrie, Astron Astrophys 284, 689, 1994), will also be observable
initially in the favourable cases, and upgrades will greatly improve the
number of observable objects. The observability of gravitational waves
emitted by binary lensing masses, in the form of modulated lensing
patterns, is a debated issue (Ragazzoni et al., MNRAS 345, 100-110,
2003) but will also become addressable observationally. The technology
readiness of Luciola approaches levels where low-orbit testing and
stepwise implementation will become feasible in the 2015-2025 time
frame. For the following decades beyond 2020, once accurate formation
flying techniques will be mastered, much larger hypertelescopes such
as the proposed 100 km Exo-Earth Imager and the 100,000 km Neutron
Star Imager should also become feasible. Luciola is therefore also
seen as a precursor toward such very powerful instruments.

---------------------------------------------------------
Title: Heavy Elements and Cool Stars
Authors: Wahlgren, Glenn M.; Carpenter, Kenneth G.; Norris, Ryan P.
2009AIPC.1094..892W Altcode: 2009csss...15..892W
We report on progress in the analysis of high-resolution near-IR
spectra of α Orionis (M2 Iab) and other cool, luminous stars. Using
synthetic spectrum techniques, we search for atomic absorption lines
in the stellar spectra and evaluate the available line parameter data
for use in our abundance analyses. Our study concentrates on the post
iron-group elements copper through zirconium as a means of investigating
the slow neutron-capture process of nucleosynthesis in massive stars
and the mechanisms that transport recently processed material up into
the photospheric region. We discuss problems with the atomic data and
model atmospheres that need to be addressed before theoretically derived
elemental abundances from pre-supernova nucleosynthesis calculations
can be tested by comparison with abundances determined from observations
of cool, massive stars.

---------------------------------------------------------
Title: UV, IR, and mm Studies of CO Surrounding the Red Supergiant
α Orionis (M2 Iab)
Authors: Harper, Graham M.; Carpenter, Kenneth G.; Ryde, Nils; Smith,
Nathan; Brown, Joanna; Brown, Alexander; Hinkle, Kenneth H.
2009AIPC.1094..868H Altcode: 2009csss...15..868H
Carbon monoxide has been detected in Betelgeuse's ultraviolet
(electronic), infrared (vibrational), and mm-radio (rotational) spectra,
but its spatial distribution has remained elusive. We have obtained new
mm-radio interferometry (CARMA), infrared spatially-resolved spectra
(Phoenix/Gemini-South), and we have performed non-LTE simulations to
help establish the spatial location of the S1 (V = 10 km/s) and S2 (V =
17 km/s) CO shells. The strong CO Fourth-Positive ultraviolet scattering
signature is apparent in the HST GHRS G140L spectrum and the S1 and
S2 shells account for much of the UV opacity. Phoenix spectra reveal
that the low velocity S1 shell is present at 1.5 arcsec West of the
star and extends out to ~4 arcsec, and its mm-radio emission appears to
originate within an 6 arcsec radius. The interpretation of the S2 shell
is less clear. The Phoenix spectra tentatively suggest that the S2 shell
extends to ~7 arcsec. The CARMA channel maps show an additional strong
narrow emission component 5 arcsec from the star, but the spectra do not
show all the expected S1 and S2 signatures. Future CARMA observations
should help to disentangle the signature of the S1 and S2 shells.

---------------------------------------------------------
Title: The Atmospheric Dynamics of α Tau (K5 III)-Clues to
Understanding the Magnetic Dynamo in Late-Type Giant Stars
Authors: Carpenter, Kenneth G.; Airapetian, Vladimir
2009AIPC.1094..712C Altcode: 2009csss...15..712C
Using HST/GHRS, HST/STIS and FUSE archival data for α Tau and the
CHIANTI spectroscopic code, we have derived line shifts, volumetric
emission measures, and plasma density estimates, and calculated
filling factors for a number of UV lines forming between 10,000 K
and 300,000 K in the outer atmosphere of this red giant star. The
data suggest the presence of low-temperature extended regions and
high-temperature compact regions, associated with magnetically open
and closed structures in the stellar atmosphere, respectively. The
signatures of UV lines from α Tau can be consistently understood
via a model of upward-traveling Alfvén waves in a gravitationally
stratified atmosphere. These waves cause nonthermal broadening in UV
lines due to unresolved wave motions and downward plasma motions in
compact magnetic loops heated by resonant Alfvén wave heating.

---------------------------------------------------------
Title: Commission 29: Stellar Spectra
Authors: Parthasarathy, Mudumba; Piskunov, Nikolai E.; Sneden,
Christopher; Carpenter, Kenneth G.; Castelli, Fiorella; Cunha, Katia;
Eenens, Phillippe R. J.; Hubeny, Ivan; Rossi, Silvia; Takada-Hidai,
Masahide; Wahlgren, Glenn M.; Weiss, Werner W.
2009IAUTA..27..209P Altcode:
The members of IAU Commission 29 Stellar Spectra are actively
engaged in the quantitative analysis of spectra of various types
of stars. With large and medium size telescopes equipped with high
resolution spectrographs LTE and Non-LTE analysis of spectra of all
types stars are being carried out. Spectra of stars in our Galaxy,
in globular and open clusters, stars in LMC and SMC and in nearby
galaxies are being studied. Accurate chemical composition analysis
of various types of stars has been carried out during the past three
years. Now the analysis of stellar spectra covers the wavelength range
from X-ray region to IR and sub-millimeter range. Recently stellar
spectra are being analysed using time-dependent, 3D, hydrodynamical
model atmospheres to derive accurate stellar abundances.

---------------------------------------------------------
Title: Mass Transport Processes and their Roles in the Formation,
Structure, and Evolution of Stars and Stellar Systems
Authors: Carpenter, Kenneth G.; Karvovska, Margarita; Schrijver,
Carolus J.; Grady, Carol A.; Allen, Ronald J.; Brown, Alexander;
Cranmer, Steven R.; Dupree, Andrea K.; Evans, Nancy R.; Guinan,
Edward F.; Harper, Graham; Labeyrie, Antoine; Linsky, Jeffrey;
Peters, Geraldine J.; Roberge, Aki; Saar, Steven H.; Sonneborn,
George; Walter, Frederick M.
2009astro2010S..40C Altcode: 2009arXiv0903.2433C
We summarize some of the compelling new scientific opportunities
for understanding stars and stellar systems that can be enabled
by sub-mas angular resolution, UV/Optical spectral imaging
observations, which can reveal the details of the many dynamic
processes (e.g., variable magnetic fields, accretion, convection,
shocks, pulsations, winds, and jets) that affect their formation,
structure, and evolution. These observations can only be provided
by long-baseline interferometers or sparse aperture telescopes in
space, since the aperture diameters required are in excess of 500 m -
a regime in which monolithic or segmented designs are not and will
not be feasible - and since they require observations at wavelengths
(UV) not accessible from the ground. Two mission concepts which could
provide these invaluable observations are NASA's Stellar Imager (SI;
http://hires.gsfc.nasa.gov/si/) interferometer and ESA's Luciola
sparse aperture hypertelescope, which each could resolve hundreds
of stars and stellar systems. These observatories will also open an
immense new discovery space for astrophysical research in general and,
in particular, for Active Galactic Nuclei (Kraemer et al. Decadal
Survey Science Whitepaper). The technology developments needed for
these missions are challenging, but eminently feasible (Carpenter et
al. Decadal Survey Technology Whitepaper) with a reasonable investment
over the next decade to enable flight in the 2025+ timeframe. That
investment would enable tremendous gains in our understanding of the
individual stars and stellar systems that are the building blocks of our
Universe and which serve as the hosts for life throughout the Cosmos.

---------------------------------------------------------
Title: Active Galactic Nuclei and their role in Galaxy Formation
and Evolution
Authors: Kraemer, Steve; Windhorst, Rogier; Carpenter, Kenneth G.;
Crenshaw, Mike; Elvis, Martin; Karovska, Margarita
2009astro2010S.162K Altcode: 2009arXiv0904.3875K
There are several key open questions as to the nature and origin of AGN
including: 1) what initiates the active phase, 2) the duration of the
active phase, and 3) the effect of the AGN on the host galaxy. Critical
new insights to these can be achieved by probing the central regions
of AGN with sub-mas angular resolution at UV/optical wavelengths. In
particular, such observations would enable us to constrain the
energetics of the AGN "feedback" mechanism, which is critical for
understanding the role of AGN in galaxy formation and evolution. These
observations can only be obtained by long-baseline interferometers
or sparse aperture telescopes in space, since the aperture diameters
required are in excess of 500 m - a regime in which monolithic or
segmented designs are not and will not be feasible and because these
observations require the detection of faint emission near the bright
unresolved continuum source, which is impossible from the ground,
even with adaptive optics. Two mission concepts which could provide
these invaluable observations are NASA's Stellar Imager (SI; Carpenter
et al. 2008 &amp; http://hires.gsfc.nasa.gov/si/) interferometer and
ESA's Luciola (Labeyrie 2008) sparse aperture hypertelescope.

---------------------------------------------------------
Title: Stellar Imager (SI) - Observing the Universe in High Definition
Authors: Carpenter, Kenneth G.; Karovska, M.; Schrijver, C. J.;
SI Development Team
2009AAS...21345113C Altcode: 2009BAAS...41..346C
Stellar Imager (http://hires.gsfc.nasa.gov/si/) is a space-based,
UV/Optical Interferometer (UVOI) with over 200x HST's resolution. It
will enable 0.1 milli-arcsec spectral imaging of stellar surfaces and
the Universe in general and open an enormous new "discovery space"
for Astrophysics with its combination of high angular resolution,
dynamic imaging, and spectral energy resolution. SI's goal is to
study the role of magnetism in the Universe and revolutionize our
understanding of: 1) Solar/Stellar Magnetic Activity and their
impact on Space Weather, Planetary Climates, and Life, 2) Magnetic
and Accretion Processes and their roles in the Origin and Evolution
of Structure and in the Transport of Matter throughout the Universe,
3) the close-in structure of Active Galactic Nuclei, and 4) Exo-Solar
Planet Transits and Disks. The SI mission is targeted for the mid
2020's - thus significant technology development in the upcoming decade
is critical to enabling it and future space-based sparse aperture
telescope and distributed spacecraft missions. The key technology
needs include: 1) precision formation flying of many spacecraft,
2) precision metrology over km-scales, 3) closed-loop control of
many-element, sparse optical arrays, 4) staged-control systems with
very high dynamic ranges (nm to km-scale). It is critical that the
importance of timely development of these capabilities is called
out in the upcoming Astrophysics and Heliophysics Decadal Surveys,
to enable the flight of such missions in the following decade. SI
is a "Landmark/Discovery Mission" in the 2005 Heliophysics Roadmap
and a candidate UVOI in the 2006 Astrophysics Strategic Plan. It is
a NASA Vision Mission ("NASA Space Science Vision Missions" (2008),
ed. M. Allen) and has also been recommended for further study in the
2008 NRC interim report on missions potentially enabled or enhanced
by an Ares V launch, although an incrementally-deployed version could
be launched using smaller rockets.

---------------------------------------------------------
Title: Exoplanet Characterization and the Search for Life
Authors: Kasting, James; Traub, W.; Roberge, A.; Leger, A.; Schwartz,
A.; Wootten, A.; Vosteen, A.; Lo, A.; Brack, A.; Tanner, A.; Coustenis,
A.; Lane, B.; Oppenheimer, B.; Mennesson, B.; Lopez, B.; Grillmair, C.;
Beichman, C.; Cockell, C.; Hanot, C.; McCarthy, C.; Stark, C.; Marois,
C.; Aime, C.; Angerhausen, D.; Montes, D.; Wilner, D.; Defrere, D.;
Mourard, D.; Lin, D.; Kite, E.; Chassefiere, E.; Malbet, F.; Tian,
F.; Westall, F.; Illingworth, G.; Vasisht, G.; Serabyn, G.; Marcy, G.;
Bryden, G.; White, G.; Laughlin, G.; Torres, G.; Hammel, H.; Ferguson,
H.; Shibai, H.; Rottgering, H.; Surdej, J.; Wiseman, J.; Ge, J.; Bally,
J.; Krist, J.; Monnier, J.; Trauger, J.; Horner, J.; Catanzarite, J.;
Harrington, J.; Nishikawa, J.; Stapelfeldt, K.; von Braun, K.; Biazzo,
K.; Carpenter, K.; Balasubramanian, K.; Kaltenegger, L.; Postman, M.;
Spaans, M.; Turnbull, M.; Levine, M.; Burchell, M.; Ealey, M.; Kuchner,
M.; Marley, M.; Dominik, M.; Mountain, M.; Kenworthy, M.; Muterspaugh,
M.; Shao, M.; Zhao, M.; Tamura, M.; Kasdin, N.; Haghighipour, N.;
Kiang, N.; Elias, N.; Woolf, N.; Mason, N.; Absil, O.; Guyon, O.;
Lay, O.; Borde, P.; Fouque, P.; Kalas, P.; Lowrance, P.; Plavchan,
P.; Hinz, P.; Kervella, P.; Chen, P.; Akeson, R.; Soummer, R.; Waters,
R.; Barry, R.; Kendrick, R.; Brown, R.; Vanderbei, R.; Woodruff, R.;
Danner, R.; Allen, R.; Polidan, R.; Seager, S.; MacPhee, S.; Hosseini,
S.; Metchev, S.; Kafka, S.; Ridgway, S.; Rinehart, S.; Unwin, S.;
Shaklan, S.; ten Brummelaar, T.; Mazeh, T.; Meadows, V.; Weiss, W.;
Danchi, W.; Ip, W.; Rabbia, Y.
2009astro2010S.151K Altcode: 2009arXiv0911.2936K
Over 300 extrasolar planets (exoplanets) have been detected orbiting
nearby stars. We now hope to conduct a census of all planets around
nearby stars and to characterize their atmospheres and surfaces with
spectroscopy. Rocky planets within their star's habitable zones have
the highest priority, as these have the potential to harbor life. Our
science goal is to find and characterize all nearby exoplanets; this
requires that we measure the mass, orbit, and spectroscopic signature of
each one at visible and infrared wavelengths. The techniques for doing
this are at hand today. Within the decade we could answer long-standing
questions about the evolution and nature of other planetary systems,
and we could search for clues as to whether life exists elsewhere in
our galactic neighborhood.

---------------------------------------------------------
Title: Stellar Imager: wavefront control
Authors: Lyon, Richard G.; Carpenter, Kenneth G.; Petrone, Peter;
Dogoda, Peter; Reed, Daniel; Mozurkewich, David
2008SPIE.7011E..31L Altcode: 2008SPIE.7011E..89L
Stellar Imager (SI) is a proposed NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI would
consist of 20 - 30 separate spacecraft flying in formation at the
Earth-Sun L2 libration point. Onboard wavefront sensing and control
is required to maintain alignment during science observations and
after array reconfigurations. The Fizeau Interferometry Testbed (FIT),
developed at the NASA/Goddard Space Flight Center, is being used to
study wavefront sensing and control methodologies for Stellar Imager
and other large, sparse aperture telescope systems. FIT initially
consists of 7 articulated spherical mirrors in a Golay pattern, and
is currently undergoing expansion to 18 elements. FIT currently uses
in-focus whitelight sparse aperture PSFs and a direct solve broadband
phase retrieval algorithm to sense and control its wavefront. Ultimately
it will use extended scene wavelength, with a sequential diversity
algorithm that modulates a subset of aperture pistons to jointly
estimate the wavefront and the reconstructed image from extended
scenes. The recovered wavefront is decomposed into the eigenmodes of
the control matrix and actuators are moved to minimize the wavefront
piston, tip and tilt in closed-loop. We discuss the testbed, wavefront
control methodology and ongoing work to increase its bandwidth from
1 per 11 seconds to a few 10's of Hertz and show ongoing results.

---------------------------------------------------------
Title: Atmospheric Dynamics in α Tau
Authors: Airapetian, Vladimir; Carpenter, K. G.
2008AAS...21116215A Altcode:
HST/GHRS, HST/STIS and FUSE observations of evolved late-type stars
demonstrated the presence of non-thermally broadened UV emission
lines forming at temperatures of 10,000 to 300,000K in almost all
of the stars. In this study we analyze CI 1993.62A, CII] 2323.5A,
SiIII 2350.17A, SiIV 1393A, CIII 977A, OIV 1401.35A and OVI 1032A
emission lines from Tau. Our analysis of these UV lines reveal
redshifts T (except for OVI 1032A), while non-thermal velocities T
. Derived emission measures indicate filling factors &lt;0.1%. These
findings force us to reconsider the definition of chromospheric and
transition regions in these stars as patchy regions or atmospheric
hot spots. According to Freytag et al. (2002), convective cells with
sizes of 0.01Rstar generate shock waves that dissipate
at lower atmospheric layers. Large-scale convective motions produce
large-scale magnetic structures in contrast to arcades of thin
solar-like loops powered by small-scale granular motions. We discuss
the model of non-linear Alfven waves amplified by resonant interaction
with sound waves and propagating upward along one (or a few) constant
pressure large-scale loop(s). As Alfven waves propagate upward in a
gravitationally stratified atmosphere, their wave amplitudes increase
causing non-thermal broadening in UV lines due to unresolved wave
motions. We discuss a model that predicts downward plasma motions
in extended loops driven by asymmetric Alfven wave heating. We
use a state-of-the-art 2.5 MHD code to show that the energy flux
density of Alfven waves (with P a few days), which are needed to
explain the radiative cooling and non-thermal broadening in the
UV lines, is consistent with the requirement to drive massive ( 10
MSun/yr) and slow ( 30 km/s) stellar winds from magnetically
open structures with the assumption of a magnetic field at the wind
base 1 G. This research is supported by the NASA Research grant
to CUA from GSFC No. NASA-NNG06GJ29G

---------------------------------------------------------
Title: The Stellar Imager
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska,
Margarita
2008nssv.book..191C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Towards a Small Prototype Planet Finding Interferometer:
The next step in planet finding and characterization in the infrared
Authors: Danchi, W. C.; Deming, D.; Carpenter, K. G.; Barry, R. K.;
Hinz, P.; Johnston, K. J.; Lawson, P.; Lay, O.; Monnier, J. D.;
Richardson, L. J.; Rinehart, S.; Traub, W.
2008arXiv0801.4752D Altcode:
During the last few years, considerable effort has been directed
towards large-scale (&gt;&gt; $1 Billion US) missions to detect
and characterize earth-like planets around nearby stars, such as
the Terrestrial Planet Finder Interferometer (TPF-I) and Darwin
missions. However, technological and budgetary issues as well as
shifting science priorities will likely prevent these missions from
entering Phase A until the next decade. The secondary eclipse technique
using the Spitzer Space Telescope has been used to directly measure
the temperature and emission spectrum of extrasolar planets. However,
only a small fraction of known extrasolar planets are in transiting
orbits. Thus, a simplified nulling interferometer, which produces
an artificial eclipse or occultation, and operates in the near-
to mid-infrared (e.g. ~ 3 to 8 or 10 microns), can characterize the
atmospheres of this much larger sample of the known but non-transiting
exoplanets. Many other scientific problems can be addressed with a
system like this, including imaging debris disks, active galactic
nuclei, and low mass companions around nearby stars. We discuss the
rationale for a probe-scale mission in the $600-800 Million range,
which we name here as the Small Prototype Planet Finding Interferometer
(SPPFI).

---------------------------------------------------------
Title: Wavefront sensing and closed-loop control for the Fizeau
interferometry testbed
Authors: Lyon, Richard G.; Carpenter, Kenneth G.; Liu, Alice; Petrone,
Peter; Dogoda, Peter; Reed, Daniel; Mozurkewich, David
2007SPIE.6687E..0HL Altcode:
Stellar Imager (SI) is a proposed NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI would
consist of 20 - 30 separate spacecraft flying in formation at the
Earth-Sun L2 libration point. Onboard wavefront sensing and control
is required to maintain alignment during science observations and
after array reconfigurations. The Fizeau Interferometry Testbed (FIT),
developed at the NASA/Goddard Space Flight Center, is being used to
study wavefront sensing and control methodologies for Stellar Imager
and other large, sparse aperture telescope systems. FIT initially
consists of 7 articulated spherical mirrors in a Golay pattern, and
is currently undergoing expansion to 18 elements. FIT currently uses
in-focus whitelight sparse aperture PSFs and a direct solve phase
retrieval algorithm to sense and control its wavefront. Ultimately
it will use extended scene wavelength, with a sequential diversity
algorithm that modulates a subset of aperture pistons to jointly
estimate the wavefront and the reconstructed image from extended
scenes. The recovered wavefront is decomposed into the eigenmodes of
the control matrix and actuators are moved to minimize the wavefront
piston, tip and tilt in closed-loop. We discuss the testbed, wavefront
control methodology and ongoing work to increase its bandwidth from
1 per 11 seconds to a few 10's of Hertz and show ongoing results.

---------------------------------------------------------
Title: Beam combination for Stellar Imager and its application to
full-aperture imaging
Authors: Mozurkewich, D.; Carpenter, K. G.; Lyon, R. G.
2007SPIE.6687E..0KM Altcode: 2007SPIE.6687E..19M
Stellar Imager (SI) will be a Space-Based telescope consisting of 20
to 30 separated apertures. It is designed for UV/Optical imaging of
stellar surfaces and asteroseismology. This report describes details
of an alternative optical design for the beam combiner, dubbed the
Spatial Frequency Remapper (SFR). It sacrifices the large field of view
of the Fizeau combiner. In return, spectral resolution is obtained
with a diffraction grating rather than an array of energy-resolving
detectors. The SFR design works in principle and has been implemented
with MIRC at CHARA for a small number of apertures. Here, we show
the number of optical surfaces can be reduced and the concept
scales gracefully to the large number of apertures needed for
Stellar Imager. We also describe a potential application of this
spatial frequency remapping to improved imaging with filled-aperture
systems. For filled-aperture imaging, the SFR becomes the core of an
improved aperture masking system. To date, aperture-masking has produced
the best images with ground-based telescopes but at the expense of
low sensitivity due to short exposures and the discarding of most
of the light collected by the telescope. This design eliminates
the light-loss problem previously claimed to be inherent in all
aperture-masking designs. We also argue that at least in principle,
the short-integration time limit can also be overcome. With these
improvements, it becomes an ideal camera for TPF-C; since it can form
speckle-free images in the presence of wavefront errors, it should
significantly relax the stability requirements of the current designs.

---------------------------------------------------------
Title: Direct UV/optical imaging of stellar surfaces: the Stellar
Imager Vision Mission
Authors: Carpenter, Kenneth G.; Lyon, Richard G.; Schrijver, Carolus;
Karovska, Margarita; Mozurkewich, David
2007SPIE.6687E..0GC Altcode: 2007SPIE.6687E..15C
The Stellar Imager (SI) is a UV/optical, space-based interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of
stellar surfaces and, via asteroseismology, stellar interiors and of
the Universe in general. SI's science focuses on the role of magnetism
in the Universe, particularly on magnetic activity on the surfaces of
stars like the Sun. SI's prime goal is to enable long-term forecasting
of solar activity and the space weather that it drives, in support of
the Living with a Star program in the Exploration Era. SI will also
revolutionize our understanding of the formation of planetary systems,
of the habitability and climatology of distant planets, and of many
magneto-hydrodynamically controlled processes in the Universe. SI
is a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar
System Connection (SSSC) Roadmap and a candidate for a "Pathways to
Life Observatory" in the Exploration of the Universe Division (EUD)
Roadmap (May, 2005). We discuss herein the science goals of the SI
Mission, a mission architecture that could meet those goals, and the
technologies needed to enable this mission. Additional information on
SI can be found at: http://hires.gsfc.nasa.gov/si/.

---------------------------------------------------------
Title: Dynamos, Asteroseismology, and the Stellar Imager
Authors: Schrijver, C. J.; Carpenter, K. G.; Karovska, M.
2007CoAst.150..364S Altcode:
The ultra-sharp images of the Stellar Imager (SI) will revolutionize
our view of many dynamic astrophysical processes: The 0.1 milli-arcsec
resolution of this deep-space telescope will transform point sources
into extended sources, and simple snapshots into spellbinding evolving
views. SI's science focuses on the role of magnetism in the Universe,
particularly on magnetic activity on the surfaces of stars like the Sun
and on the subsurface flows that drive this activity. SI's prime goal
is to image magnetically active stars with enough resolution to map
their evolving dynamo patterns and their internal flows. By exploring
the Universe at ultra-high resolution, SI will also revolutionize our
understanding of the formation of planetary systems, of the habitability
and climatology of Earth as well as distant exoplanets, and of many
magneto-hydrodynamically controlled structures and processes in the
Universe. See http://hires.gsfc.nasa.gov/si/ for details on the
Stellar Imager mission.

---------------------------------------------------------
Title: Stellar Imager
Authors: Carpenter, Kenneth
2007STIN...0734890C Altcode:
The Stellar Imager (SI) is one of NASA's "Vision Missions" - concepts
for future, space-based, strategic missions that could enormously
increase our capabilities for observing the Cosmos. SI is designed
as a UV/Optical Interferometer which will enable 0.1 milli-arcsecond
(mas) spectral imaging of stellar surfaces and, via asteroseismology,
stellar interiors and of the Universe in general. The ultra-sharp images
of the Stellar Imager will revolutionize our view of many dynamic
astrophysical processes by transforming point sources into extended
sources, and snapshots into evolving views. SI, with a characteristic
angular resolution of 0.1 milli-arcseconds at 2000 Angstroms, represents
an advance in image detail of several hundred times over that provided
by the Hubble Space Telescope. The Stellar Imager will zoom in on what
today-with few exceptions - we only know as point sources, revealing
processes never before seen, thus providing a tool as fundamental to
astrophysics as the microscope is to the study of life on Earth. SI's
science focuses on the role of magnetism in the Universe, particularly
on magnetic activity on the surfaces of stars like the Sun. It's prime
goal is to enable long-term forecasting of solar activity and the space
weather that it drives, in support of the Living With a Star program
in the Exploration Era. SI will also revolutionize our understanding of
the formation of planetary systems, of the habitability and climatology
of distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. Stellar Imager is included as a "Flagship
and Landmark Discovery Mission" in the 2005 Sun Solar System Connection
(SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory"
in the Exploration of the Universe Division (EUD) Roadmap (May, 2005)
and as such is a candidate mission for the 2025-2030 timeframe. An
artist's drawing of the current "baseline" concept for SI is presented.

---------------------------------------------------------
Title: Steps Toward a UV/Optical Interferometer in Space: FIT &amp;
SIFFT
Authors: Carpenter, Kenneth G.; Lyon, R. G.; Liu, A.; Dogoda, P.;
Petrone, P.; Mozurkewich, D.; Miller, D.; Mohan, S.; Stahl, P.
2006AAS...20916401C Altcode: 2006BAAS...38R1129C
We summarize the goals and result-to-date of a ROSES/APRA-sponsored
program to develop two of the major technologies needed to enable
the design and construction of future large baseline, space-based
Interferometric and Sparse Aperture Telescope missions (e.g., Stellar
Imager, Life Finder, Black Hole Imager, and Planet Imager). The Fizeau
Interferometer Testbed (FIT) is being used to develop and demonstrate
nm-level, closed-loop optical control of mirrors (i.e., control of tip,
tilt, piston, translation of array elements) and the overall system
to keep multiple beams in phase and optimize imaging of a Fizeau
interferometric system and to assess various image reconstruction
algorithms (phase diversity, clean, maximum entropy method, etc.) for
utility and accuracy. The Synthetic Imaging Formation Flying Testbed
(SIFFT) is, in parallel, being used to develop and demonstrate
algorithms for autonomous cm-level precision formation flying, which
can be combined in the future with the higher precision optical control
systems (e.g., those developed on the FIT) to fully enable synthetic
aperture imaging systems. The ultimate goal of this research is the
demonstration of closed-loop performance of a unified system which
combines formation flying and nm-level optical control systems (based
on analysis of the science data stream) to maintain phasing of a large
array of space-borne mirrors, as needed for missions like those listed
above, as well as smaller baseline Precursor missions that may pave
the path to the larger strategic missions.

---------------------------------------------------------
Title: Heavy Element Abundances in the Photospheres of Cool
Supergiants
Authors: Wahlgren, Glenn M.; Lundqvist, M.; Carpenter, K. G.
2006AAS...209.9304W Altcode: 2006BAAS...38.1030W
We report on a program to determine the chemical composition of massive,
cool supergiant photospheres. We concentrate on elements heavier than
the iron group, addressing the question of whether nuclear by-products
from the weak s-process have been brought to the surface by convective
processes. For massive stars, atoms with mass up to approximately
A = 100 are thought to be formed by neutron capture via the weak
s-process. The abundances of these elements have been calculated
by other researchers to be a function of stellar mass. Our
initial work has concentrated on the identification of useful atomic
spectral lines at infrared wavelengths, where absorption from molecular
species is reduced relative to that at optical wavelengths for M-type
stars. Abundances are determined by synthetic spectrum fitting to line
profiles in high-resolution spectra. We present results for the
cool, supergiant Betelgeuse (M2 Iab). Abundances are determined for a
number of heavy elements, and despite large uncertainties attributed to
the available atomic data (oscillator strengths), a distinct enhancement
of Sr is determined after correcting for non-LTE effects. Such an
enhancement is predicted by models of interior nucleosynthesis via
neutron capture. Our results illuminate the problems that must be
overcome before being able to derive abundances with the accuracy
required for rigorous comparison with theoretical calculations. We
also present our approach to applying the results for Betelgeuse to
additional cool supergiants.

---------------------------------------------------------
Title: The Stellar Imager (SI) vision mission
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska,
Margarita
2006SPIE.6268E..21C Altcode: 2006astro.ph..6411C; 2006SPIE.6268E..63C
The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of
stellar surfaces and of the Universe in general and asteroseismic
imaging of stellar interiors. SI is identified as a "Flagship and
Landmark Discovery Mission" in the 2005 Sun Solar System Connection
(SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory"
in the Exploration of the Universe Division (EUD) Roadmap (May,
2005). SI will revolutionize our view of many dynamic astrophysical
processes: its resolution will transform point sources into extended
sources, and snapshots into evolving views. SI's science focuses
on the role of magnetism in the Universe, particularly on magnetic
activity on the surfaces of stars like the Sun. SI's prime goal is to
enable long-term forecasting of solar activity and the space weather
that it drives. SI will also revolutionize our understanding of the
formation of planetary systems, of the habitability and climatology
of distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. The results of the SI "Vision Mission"
Study are presented in this paper. Additional information on the SI
mission concept and related technology development can be found at URL:
http://hires.gsfc.nasa.gov/si/.

---------------------------------------------------------
Title: SI - The Stellar Imager: Results from the Vision Mission Study
Authors: Carpenter, K. G.; Schrijver, C. J.; Karovska, M.; SI Vision
Mission Study Team
2005AAS...207.2307C Altcode: 2005BAAS...37R1196C
The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer
designed to enable 0.1 milli-arcsecond (mas) spectral imaging of
stellar surfaces and stellar interiors (via asteroseismology) and of
the Universe in general. SI was included as a "far horizon" or "Vision
Mission" in the 2000 and 2003 SEC Roadmaps and is now identified as
a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar
System Connection (SSSC) Roadmap and as a candidate for a "Pathways
to Life Observatory" in the Exploration of the Universe Division (EUD)
Roadmap (May, 2005). The ultra-sharp images of the Stellar Imager will
revolutionize our view of many dynamic astrophysical processes: The
0.1 mas resolution of this deep-space telescope will transform point
sources into extended sources, and snapshots into evolving views. SI's
science focuses on the role of magnetism in the Universe, particularly
on magnetic activity on the surfaces of stars like the Sun. SI's prime
goal is to enable long-term forecasting of solar activity and the space
weather that it drives in support of the Living With a Star program in
the Exploration Era. SI will also revolutionize our understanding of
the formation of planetary systems, of the habitability and climatology
of distant planets, and of many magneto-hydrodynamically controlled
processes in the Universe. The results of a just-concluded "Vision
Mission" Study of Stellar Imager will be presented in this paper. This work was supported, in part, by Vision Mission Study grants
from NASA HQ to NASA-GSFC and from GSFC to Smithsonian Astrophysical
Observatory, Seabrook Engineering, SUNY/Stonybrook, U. Colorado/Boulder,
and STScI. Substantial complementary internal institutional support
is gratefully acknowledged from all of the participating institutions.

---------------------------------------------------------
Title: High-Mass Triple Systems: The Classical Cepheid Y Carinae
Authors: Evans, Nancy Remage; Carpenter, Kenneth G.; Robinson, Richard;
Kienzle, Francesco; Dekas, Anne E.
2005AJ....130..789E Altcode: 2005astro.ph..4169E
We have obtained a Hubble Space Telescope STIS ultraviolet
high-dispersion echelle-mode spectrum of the binary companion of the
double-mode classical Cepheid Y Car. The velocity measured for the
hot companion from this spectrum is very different from reasonable
predictions for binary motion, implying that the companion is
itself a short-period binary. The measured velocity changed by
7 km s-1 during the 4 days between two segments of the
observation, confirming this interpretation. We summarize “binary”
Cepheids that are in fact members of a triple system and find that
at least 44% are triples. The summary of information on Cepheids
with orbits makes it likely that the fraction is underestimated. Based on observations made with the NASA/ESA Hubble Space Telescope,
obtained at the Space Telescope Science Institute, which is operated
by the Association of Universities for Research in Astronomy, Inc.

---------------------------------------------------------
Title: The Stellar Imager: a deep-space telescope to image stellar
surfaces
Authors: Schrijver, C. J.; Carpenter, K. G.; Karovska, M.; Si Vision
Mission Team
2005ESASP.560..951S Altcode: 2005csss...13..951S
No abstract at ADS

---------------------------------------------------------
Title: Planetary Environment Study at Sub-milliarcsecond Resolution
Authors: Ragozzine, D.; Karovska, M.; Hartmann, L.; Sasselov, D.;
Carpenter, K.; SI Team
2004AAS...205.1718R Altcode: 2004BAAS...36.1368R
The Stellar Imager (SI; http://hires.gsfc.nasa.gov/ ∼si ) is
a NASA Vision Mission, conceived of as a space-based UV-Optical
long-baseline interferometer that will provide sub-milliarcsecond
imaging capabilities. We present results from our study of how
SI could be used to answer key questions about planet formation
and planet-star-disk interactions. SI would be able to resolve
and characterize star-disk interactions at a few stellar radii,
including accretion and inner disk edge heating. Simple models of
T-Tauri stars are used to probe SI's sensitivity to various critical
parameters and geometries. By observing H2-flourescent lines in the
UV, the contrast between the luminosity of the star and the gas can
be improved. A list of potential targets among known planet-harboring
stars is also presented with the hope of resolving possible star-planet
interactions. Acknowledgement: This work was supported by the SI
Vision Mission study grant NNG04GM92G from NASA/GSFC to SAO. MK is a
member of the Chandra X-ray Center (NASA contract NAS8-39073).

---------------------------------------------------------
Title: Stellar Imager (SI) Vision Mission Science Drivers
Authors: Karovska, M.; Carpenter, K. G.; Schrijver, C. J.; SI Mission
Concept Development
2004AAS...20518005K Altcode: 2005BAAS...37..384K
We describe the key scientific drivers for the Stellar Imager (SI)
Vision Mission - a UV-optical 0.1 milli-arcsecond (mas) imaging space
interferometer. Ultra-high sub-mas angular resolution imaging at UV and
optical wavelengths is key to studies of magnetic field structures that
govern the formation of stars and planetary systems, the habitability of
planets, long-term space weather in the Exploration era, and transport
processes on many scales in the Universe. Magnetic fields affect the
evolution of structure in the Universe and drive solar and stellar
activity which is a key to life's origin and survival. However,
our understanding of how magnetic fields form, operate, and evolve
is currently very limited, even for the nearest star, our Sun. The key science goal of the Stellar Imager Mission is to obtain an
understanding of stellar dynamos, and in particular the solar dynamo,
through a population study of other stars representing a broad range
of stellar parameters and activity. The end goal is to understand the
variable impact of stellar magnetic activity on planetary climates and
the origin and maintenance of life. Improved knowledge of solar-type
dynamo activity and the interaction of global fields and flows
is also crucial for developing models for long-term space weather
forcasting. Furthermore, SI's high-angular resolution capabilities, over
two magnitudes better then the HST, will enable unprecedented studies
of dynamo and accretion-driven processes, and mass exchange and mass
flows in a wide variety of galactic and extragalactic sources, including
young star/disk systems, solar-type and evolved stars and astrospheres,
numerous interacting binaries, and SN, AGN, and black hole environments.

---------------------------------------------------------
Title: The Stellar Imager (SI): Preliminary Results from the Ongoing
Vision Mission Study
Authors: Carpenter, K. G.; Schrijver, C. J.; SI Mission Concept
Development Team
2004AAS...205.0509C Altcode: 2004BAAS...36.1342C; 2004AAS...205..509C
The Stellar Imager (SI) is a "Vision Mission" in the far-horizon
NASA Roadmap, conceived for the purpose of understanding the
effects of stellar magnetic fields, the dynamos that generate them,
and the internal structure and dynamics of the stars in which they
exist. The ultimate goal is to achieve the best possible forecasting
of solar/stellar activity and to understand the impact of that
activity on planetary climates and the origin and maintenance of
life in the Universe. The science goals of SI require an ultra-high
angular resolution, at ultraviolet wavelengths, on the order of 100
micro-arcsec and baselines on the order of 0.5 km. SI's resolution will
make it an invaluable resource for many other areas of astrophysics,
including studies of AGN's, supernovae, cataclysmic variables, young
stellar objects, QSO's, and stellar black holes. These requirements
call for a large, multi-spacecraft (&gt;20) imaging interferometer,
utilizing precision formation flying in a stable environment, such as
in a Lissajous orbit around the Sun-Earth L2 point. In this paper,
we present an update on the ongoing SI Vision Mission concept and
technology development studies. The SI Mission Concept Study is
supported, in part, by grants from NASA-HQ through the 2003 Vision
Mission NRA.

---------------------------------------------------------
Title: Apodized square aperture plus occulter concept for TPF
Authors: Jordan, Ian J. E.; Schultz, Alfred B.; Lyon, Richard G.; Hart,
Helen M.; Bruhweiler, Frederick; Fraquelli, Dorothy A.; Carpenter,
Kenneth G.; Kochte, Mark; Hollis, Jan M.
2004SPIE.5487.1391J Altcode:
The standard approach to achieving TPF-level starlight suppression
has been to couple a few techniques together. Deployment of a low-
or medium-performance external occulter as the first stage of
starlight suppression reduces manufacturing challenges, mitigates
under-performance risks, lowers development costs, and hastens
launch date for TPF. This paper describes the important aspects of a
conceptual 4-metre apodized square aperture telescope system utilizing a
low-performance external occulter. Adding an external occulter to such a
standard TPF design provides a benefit that no other technique offers:
scattered and diffracted on-axis starlight is suppressed by orders of
magnitude before reaching the telescope. This translates directly into
relaxed requirements on the remainder of the optical system.

---------------------------------------------------------
Title: Metrology and pointing for astronomical interferometers
Authors: Phillips, James D.; Carpenter, Kenneth G.; Gendreau, Keith
C.; Karovska, Margarita; Kaaret, Philip E.; Reasenberg, Robert D.
2004SPIE.5491..320P Altcode:
Metrology and pointing will be enabling technologies for a new
generation of astronomical missions having large and distributed
apertures and delivering unprecedented performance. The UV
interferometer Stellar Imager would study stellar dynamos by imaging
magnetic activity on the disks of stars in our Galaxy. The X-ray
interferometer Black Hole Imager would study strong gravity physics and
the formation of jets by imaging the event horizons of supermassive
black holes. These missions require pointing to microarcseconds or
better, and metrology to nm accuracy of optical elements separated by
km, for control of optical path difference. This paper describes a
metrology and pointing system that meets these requirements for the
Stellar Imager. A reference platform uses interferometers to sense
alignment with a guide star. Laser gauges determine mirror positions in
the frame of the reference platform, and detector position is monitored
by laser gauges or observations of an artificial star. Applications
to other astronomical instruments are discussed.

---------------------------------------------------------
Title: The Fizeau interferometer testbed (FIT): developing and
testing the technologies needed for space-based interferometric
imaging systems
Authors: Mazzuca, Lisa M.; Carpenter, Kenneth G.; Lyon, Richard G.;
Marzouk, Joe; Petrone, Peter, III; Cottle, Paul; Dogoda, Peter; Huet,
Hubert; Liiva, Peter; Mozurkewich, David; Armstrong, J. T.; Zhang,
Xiaolei; Solyar, Gregory; Mundy, Lee G.
2004SPIE.5491.1034M Altcode:
The Fizeau Interferometer Testbed (FIT) is a ground-based laboratory
experiment at Goddard Space Flight Center (GSFC) designed to develop
and test technologies that will be needed for future interferometric
spacecraft missions. Specifically, the research from this experiment
is a proof-of-concept for optical accuracy and stability, closed-loop
control algorithms, optimal sampling methodology of the Fourier
UV-plane, computational models for system performance, and image
synthesis techniques for a sparse array of 7 to 30 mirrors. It will
assess and refine the technical requirements on hardware, control,
and imaging algorithms for the Stellar Imager (SI), its pathfinder
mission, and other sparse aperture and interferometric imaging mission
concepts. This ground-based optical system is a collaborative effort
between NASA's GSFC, Sigma Space Corporation, the Naval Research
Laboratory, and the University of Maryland. We present an overview of
the FIT design goals and explain their associated validation methods. We
further document the design requirements and provide a status on their
completion. Next, we show the overall FIT design, including the optics
and data acquisition process. We discuss the technologies needed
to insure success of the testbed as well as for an entire class of
future mission concepts. Finally, we compare the expected performance
to the actual performance of the testbed using the initial array of
seven spherical mirrors. Currently, we have aligned and phased all
seven mirrors, demonstrated excellent system stability for extended
periods of time, and begun open-loop operations using "pinhole" light
sources. Extended scenes and calibration masks are being fabricated
and will shortly be installed in the source module. Installation of
all the different phase retrieval/diversity algorithms and control
software is well on the way to completion, in preparation for future
tests of closed-loop operations.

---------------------------------------------------------
Title: Fizeau interferometry testbed: wavefront control
Authors: Lyon, Richard G.; Carpenter, Kenneth G.; Mazzuca, Lisa;
Huet, Hubert; Cottle, Paul W.; Petrone, Peter P., III; Dagoda, Peter;
Liiva, Peter; Marzouk, Joe; Solyar, Gregory; Mozurkewich, David;
Zhang, Xiaolei; Armstrong, Thomas
2004SPIE.5487..963L Altcode:
Stellar Imager (SI) is a potential NASA space-based UV imaging
interferometer to resolve the stellar disks of nearby stars. SI
would consist of 20 - 30 separate spacecraft flying in formation at
the Earth-Sun L2 libration point. Onboard wavefront control would
be required to initially align the formation and maintain alignment
during science observations and after array reconfiguration. The Fizeau
Interferometry Testbed (FIT) is a testbed currently under development
at the NASA/Goddard Space Flight Center to develop and study the
wavefront control methodologies for Stellar Imager and other large,
sparse aperture telescope systems. FIT consists of 7 articulated
spherical mirrors in a Golay pattern, expandable up to 30 elements,
and reconfigurable into multiple array patterns. FIT"s purpose is to
demonstrate image quality versus array configuration and to develop
and advance the wavefront control for SI. FIT uses extended scene
wavelength, focus and field diversity to estimate the wavefront across
the set of apertures. The recovered wavefront is decomposed into the
eigenmodes of the control matrix and actuators are moved to minimize the
wavefront piston, tip and tilt. Each mirror"s actuators are 3 degrees of
freedom, however, they do not move each of the mirrors about a point on
each mirrors surface, thus the mapping from wavefront piston, tip/tilt
to mirror piston, tip/tilt is not diagonal. We initially estimate this
mapping but update it as part of wavefront sensing and control process
using system identification techniques. We discuss the FIT testbed,
wavefront control methodology, and show initial results from FIT.

---------------------------------------------------------
Title: Fabrication and characterization of the Fizeau interferometer
testbed
Authors: Petrone, Peter, III; Carpenter, Kenneth G.; Clark, Dave;
Cottle, Paul; Dogoda, Peter; Huet, Hubert; Liiva, Peter; Lyon, Richard
G.; Marzouk, Joe; Mazzuca, Lisa M.; McAndrew, Dave; Solyar, Gregory
2004SPIE.5491.1776P Altcode:
The Fizeau Interferometer Testbed (FIT) is a ground-based system that
will be used for the development and testing of technologies relevant
to Stellar Imager (SI) and other sparse aperture/Fizeau imaging
interferometer mission concepts. The testbed will utilize image-based
wavefront sensing and control to co-phase and maintain closed-loop
control over a Sparse Aperture Array (SAA) consisting of spherical
mirror elements. The SAA is a re-configurable assembly baselined to
incorporate between seven (initially) and thirty 12.5mm diameter (R =
4000mm) mirror elements. In this paper we describe the fabrication,
alignment, and initial calibration of the phase I (7 primary elements)
FIT hardware and discuss various factors impacting the performance
and stability of the testbed.

---------------------------------------------------------
Title: The Stellar Imager (SI): a revolutionary large-baseline
imaging interferometer at the Sun-Earth L2 point
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Allen, Ronald
J.; Brown, Alexander; Chenette, David; Danchi, William C.; Karovska,
Margarita; Kilston, Steven; Lyon, Richard G.; Marzouk, Joe; Mazzuca,
Lisa M.; Moe, Rud V.; Walter, Frederick; Murphy, Neil
2004SPIE.5491..243C Altcode:
The Stellar Imager (SI) is a far-horizon or "Vision" mission in the
NASA Sun-Earth Connection (SEC) Roadmap, conceived for the purpose
of understanding the effects of stellar magnetic fields, the dynamos
that generate them, and the internal structure and dynamics of the
stars in which they exist. The ultimate goal is to achieve the best
possible forecasting of solar/stellar activity and its impact on life
in the Universe. The science goals of SI require an ultra-high angular
resolution, at ultraviolet wavelengths, on the order of 0.1 milliarcsec
and thus baselines on the order of 500 meters. These requirements
call for a large, multi-spacecraft (&gt;20) imaging interferometer,
utilizing precision formation flying in a stable environment, such as
in a Lissajous orbit around the Sun-Earth L2 point. SI's resolution
(several 100 times that of HST) will make it an invaluable resource
for many other areas of astrophysics, including studies of AGN's,
supernovae, cataclysmic variables, young stellar objects, QSO's,
and stellar black holes. In this paper, we present an update on
the ongoing mission concept and technology development studies for
SI. These studies are designed to refine the mission requirements
for the science goals, define a Design Reference Mission, perform
trade studies of selected major technical and architectural issues,
improve the existing technology roadmap, and explore the details of
deployment and operations, as well as the possible roles of astronauts
and/or robots in construction and servicing of the facility.

---------------------------------------------------------
Title: Imaging Terrestrial Planets
Authors: Kochte, M.; Schultz, A. B.; Fraquelli, D.; Jordan, I. J. E.;
Lyon, R. G.; Carpenter, K. G.; Hart, H. M.; Disanti, M.; Bruhweiler,
F.; Miskey, C.; Rodrigue, M.; Fadali, M. S.; Skelton, D.; Cheng, K. -P.
2004AIPC..713..223K Altcode:
We present optical simulations of a new approach to directly image
terrestrial planets. Terrestrial planets typically are 10 orders
of magnitude fainter than the central star, a difficult challenge
for any optical system. Our studies show that the combination
of an external occulter and an apodizer yields the required
contrast, with significantly reduced requirements on stray light and
diffraction. This mitigates the very high mirror tolerances required
of other coronagraphic methods and makes exo-planet detection feasible
with current technology.

---------------------------------------------------------
Title: The Fizeau Interferometer Testbed (FIT): Developing and
Testing the Technologies Needed for Space-Based Interferometric
Imaging Systems
Authors: Mazzuca, L. M.; Carpenter, K. G.; Lyon, R. G.; Marzouk, J.;
Cottle, P.; Dogoda, P.; Huet, H.; Liiva, P.; Petrone, P.; Armstrong,
J. T.; Zhang, X.; Mundy, L.; Mozurkewich, D.; Solyar, G.
2004AAS...204.0812M Altcode: 2004BAAS...36..791M
The Fizeau Interferometer Testbed (FIT) is a ground-based laboratory
experiment at Goddard Space Flight Center (GSFC) designed to develop
and test technologies that will be needed for future interferometric
spacecraft missions. Specifically, the research from this experiment
is a proof-of-concept for optical accuracy and stability, closed-loop
control algorithms, optimal sampling methodology of the Fourier
UV-plane, computational models for system performance, and image
synthesis techniques for a sparse array of 7 to 30 mirrors. It will
assess and refine the technical requirements on hardware, control,
and imaging algorithms for the Stellar Imager (SI), its pathfinder
mission, and other sparse aperture and interferometric imaging mission
concepts. This ground-based optical system is a collaborative effort
between NASA's GSFC, Sigma Space Corporation, the Naval Research
Laboratory, and the University of Maryland. We present an overview
of the final optical design, detector system, and data acquisition
process. We further compare the expected performance to the actual
performance of the testbed using the initial array of seven spherical
mirrors. Currently, we have aligned and phased all seven mirrors,
demonstrated excellent system stability for extended periods of time,
and begun open-loop operations using "pinhole" light sources. Extended
scenes and calibration masks are being fabricated and will shortly
be installed in the source module. Installation of all the different
phase retrieval/diversity algorithms and control software is well on
the way to completion, in preparation for future tests of closed-loop
operations.

---------------------------------------------------------
Title: The O VI and C III Lines at 1032 and 977 Å in Hyades F Stars
Authors: Böhm-Vitense, Erika; Robinson, Richard D.; Carpenter,
Kenneth G.
2004ApJ...606.1174B Altcode:
We continue our investigations into the mechanisms heating the outer
layers of cool dwarf stars. In this study we specifically seek to
determine whether in the layers with temperatures around 250,000-300,000
K, in which the O VI lines are emitted, the temperatures are determined
by heat conduction from the coronae or by the same processes that
heat the lower temperature regions. To study this we discuss here 22
spectra of Hyades F stars taken by the Far Ultraviolet Spectroscopic
Explorer (FUSE) satellite to study the O VI lines at 1032 Å and the C
III lines at 977 Å and compare them with other lower transition layer
lines, observed with HST and IUE, and with existing X-ray data. For our
targets with B-V&gt;0.4, the X-ray fluxes of single F stars increase,
on average, slowly with increasing B-V, while the O VI line fluxes show
the same steep decrease around B-V=0.43 as previously found for the
lower temperature transition layer lines. For single stars the X-ray
fluxes decrease with increasing vsini, except for the stars with B-V
between 0.418 and 0.455, while for the O VI lines, as for the other
transition layer lines, fluxes increase with increasing vsini, if vsini
is larger than 30 km s-1. For smaller vsini, line fluxes are
independent of vsini. The B-V and vsini dependences of the O VI line
fluxes are then very different from those of the X-ray fluxes. We thus
conclude that for electron temperature Te below 300,000 K,
the transition layers for Hyades F stars are not mainly heated by
heat conduction from their coronae. Based on observations made
with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE)
telescope, which is operated for NASA by Johns Hopkins University,
under contract NAS5-32985.

---------------------------------------------------------
Title: The Stellar Imager (SI) “Vision Mission"
Authors: Carpenter, K.; Danchi, W.; Leitner, J.; Liu, A.; Lyon,
R.; Mazzuca, L.; Moe, R.; Chenette, D.; Schrijver, C.; Kilston, S.;
Karovska, M.; Allen, R.; Brown, A.; Marzouk, J.; Murphy, N.; Walter, F.
2004AAS...204.0810C Altcode: 2004BAAS...36..791C
The Stellar Imager (SI) is a `Vision' mission in the Sun-Earth
Connection (SEC) Roadmap, conceived for the purpose of understanding
the effects of stellar magnetic fields, the dynamos that generate
them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best possible
forecasting of solar/stellar magnetic activity and its impact on life
in the Universe. The science goals of SI require an ultra-high angular
resolution, at ultraviolet wavelengths, on the order of 100 micro-arcsec
and thus baselines on the order of 0.5 km. These requirements call for
a large, multi-spacecraft (&gt;20) imaging interferometer, utilizing
precision formation flying in a stable environment, such as in a
Lissajous orbit around the Sun-Earth L2 point. SI's resolution will
make it an invaluable resource for many other areas of astrophysics,
including studies of AGN's, supernovae, cataclysmic variables, young
stellar objects, QSO's, and stellar black holes. We present here
an overview of the ongoing mission concept and technology development
studies for SI. These studies are designed to refine the mission
requirements for the science goals, define a Design Reference Mission,
perform trade studies of selected major technical and architectural
issues, improve the existing technology roadmap, and explore the
details of deployment and operations, as well as the possible roles
of astronauts and/or robots in construction and servicing of the
facility. Additional information on SI mission concepts and technology
can be found at URL: http://hires.gsfc.nasa.gov/ ∼si . The SI
Mission Concept Study is supported, in part, by grants from NASA-HQ
through the 2003 Vision Mission NRA.

---------------------------------------------------------
Title: Surprising Differences in the Winds and Mass-Loss Rates of
Two M-Giant Stars: Gamma Cru (M3.5III) and Mu Gem (M3III)
Authors: Carpenter, K. G.; Robinson, R. D.
2003AAS...203.4902C Altcode: 2003BAAS...35Q1284C
We have assessed important parameters of the stellar winds of two very
similar M giant stars, Gamma Cru (M3.5III) and Mu Gem (M3III), using
high resolution HST/GHRS spectra and found surprising differences
in the characteristics of their winds and in their total mass-loss
rates. The wind parameters, including flow and turbulent velocities,
the optical depth of the wind above the region of photon creation,
and the mass-loss rate, have been estimated by fitting line profiles
computed using the "Sobolev with Exact Integration" (SEI) radiative
transfer code (Lamars et al. 1987), along with simple models of the
outer atmospheric structure and wind. These computed profiles are fit
to chromospheric emission lines which show self-absorptions produced
by the photon-scattering winds of these stars. The SEI code has the
advantage of being computationally fast and allows a great number
of possible wind models to be examined. The analysis is iterative in
nature: we specify estimates of the wind parameters, calculate line
profiles for the Mg II (UV1) lines and a range of unblended Fe II
lines (which have a wide range of wind opacities and therefore probe
different heights in the atmosphere), compare the computed profiles
with the observations, and modify the assumed wind properties until
the predicted profiles match the observations over as many lines as
possible.. Surprisingly, we find that the Gamma Cru wind exhibits a
significantly higher terminal velocity, wind turbulence, and mass-loss
rate than its fellow M-giant Mu Gem.

---------------------------------------------------------
Title: Imaging terrestrial planets with a free-flying occulter and
space telescope: an optical simulation
Authors: Schultz, Alfred B.; Lyon, Richard G.; Kochte, Mark; Fraquelli,
Dorothy A.; Bruhweiler, Frederick; Jordan, Ian J. E.; Carpenter,
Kenneth G.; DiSanti, Michael A.; Miskey, Cherie; Rodrigue, Melodi;
Fadali, M. S.; Skelton, Dennis; Hart, Helen M.; Cheng, Kwang-Ping
2003SPIE.5170..262S Altcode:
In this manuscript, we further develop our concepts for the free-flying
occulter space-based mission, the Umbral Missions Blocking Radiating
Astronomical Sources (UMBRAS). Our optical simulations clearly show
that an UMBRAS-like mission designed around a 4-m telescope and 10-m
occulter could directly image terrestrial planets. Such a mission
utilizing existing technology could be built and flown by the end of the
decade. Moreover, many of the other proposed concepts for Terrestrial
Planet Finder (TPF) could significantly benefit by using an external
occulter. We present simultations for an optical design comprising a
square aperture telescope plus square external occulter. We show that
the entire diffraction pattern, which is propagated from occulter to
telescope and through telescope to focal plane, may be characterized
by two parameters, the Fresnel number and the ratio of the telescope
diameter to the occulter width. Combining the effects of a square
occulter with apodization provides a much more rapid roll-off in the
PSF intensity between the diffraction spikes than may be achieved
with an unapodized telecope aperture and occulter. We parameterize our
results with respect to wavefront quality and compare them against other
competing methods for exo-planet imaging. The combination of external
occulter and apodization yields the required contrast in the region
of the PSF essential for exo-planet detection. An occulter external
to the telescope (i.e., in a separate spacecraft, as opposed to a
classical coronagraph with internal occulter) reduces light scatter
within the telescope by approximately 2 orders of magnitude. This is
due to less light actually entering the telescope. Reduced scattered
light significantly relaxes the constraints on the mirror surface
roughness, especially in the mid-spatial frequencies critical for
planet detection. This study, plus our previous investigations of
engineering as well as spacecraft rendezvous and formation flying
clearly indicates that the UMBRAS concept is very competitive with,
or superior to, other proposed concepts for TPF missions.

---------------------------------------------------------
Title: Imaging the Surfaces and Interiors of Other Stars: The Stellar
Imager (SI) Mission Concept
Authors: Carpenter, K. G.; Lyon, R. G.; Schrijver, C. J.; Mundy,
L. J.; Allen, R. J.; Rajagopal, J.
2003csss...12.1091C Altcode:
The Stellar Imager (SI) is envisioned as a large (0.5 km diameter)
space-based, UV-optical interferometer. It is designed to image surface
features and, through asteroseismology, sub-surface structures of
other stars and measure their spatial and temporal variations. These
observations are needed to improve our understanding of the underlying
dynamo process(es) and enable improved forecasting of solar/stellar
activity and its impact on planetary climates and life. Schrijver and
Carpenter (this volume) discuss the science goals of the mission in
detail, while in this paper we discuss the performance requirements
implied by the science goals and how these translate into specific
design requirements on the mission architecture, and we present some
preliminary visions for how the required observations (e.g., 1000 pixel,
100 micro-arcsec resolution, UV-optical images of the surface of nearby
dwarf stars) for this ambitious project might be obtained.

---------------------------------------------------------
Title: Future Capabilities for Solar/Stellar Observations
Authors: Carpenter, K.; Hassler, D.; Berger, T.; Bastian, T.;
Pallavicini, R.; Balachandran, S.
2003csss...12..359C Altcode:
This session outlines the potential instrumental capabilities for the
observation of cool stars and the Sun. The individual contributions
cover space-based solar missions (Hassler), ground-based solar
optical/IR instruments (Berger), solar-stellar radio capabilities
(Bastian), space-based stellar missions (Carpenter), ground-based
optical (Pallavicini) and infrared facilities (Balachandran) for
stellar observations.

---------------------------------------------------------
Title: Winds from “Non-Coronal” and “Hybrid” Stars Driven by
MHD Waves
Authors: Airapetian, V. S.; Carpenter, K.; Ofman, L.
2003AAS...202.3214A Altcode: 2003BAAS...35..745A
Observations obtained with IUE, HST and FUSE provide extensive data
on atmospheric heating and wind dynamics for late-type luminous
stars. The physical processes which drive winds in these stars are
poorly understood, despite decades of study. In our previous study we
have shown that observational signatures of winds can be interpreted
by our model of winds driven by propagated Alfvén waves in stellar
atmospheres and launched at a single frequency at the wind base
(Airapetian et al. 2000). We extend our MHD calculations of winds
from luminous late-type stars to include an Alfvén wave driver
with a broad-band frequency range. The calculations are applied to
“non-coronal” (α Tau) and “hybrid” (β Dra) giant stars to
consistently reproduce the observed velocity profiles of the winds,
its terminal velocity, the turbulent broadening of UV lines and mass
loss rates. The nature of wind variability in luminous late-type stars
is discussed. We also present the preliminary results of our first
MHD and LTE radiative transfer calculations to model the UV spectra
from the K5 giant, α Tau. This research is supported by the NASA
Research grant from GSFC No. NAG5-12869.

---------------------------------------------------------
Title: A novel process to fabricate mirrors with very long radius
and ultrasmooth surfaces
Authors: Chen, Peter C.; Carpenter, Kenneth G.; Romeo, Robert C.
2003SPIE.4854...21C Altcode:
During the course of performing space flight qualification testing of
composite mirrors at NASA GSFC, a serendipitious event was observed
which, in retrospect, should have been obvious. Investigation of this
phenomenon leads to a promising avenue towards the fabrication of large
aperture precision spherical mirrors with very long radius of curvature
(&gt;f/100). Such mirrors are required for future missions such as the
Stellar Imager. We report on the observation and analysis of the event,
optical measurements, and the development of associated active figure
control systems.

---------------------------------------------------------
Title: Simulating dilute-aperture imaging: The Stellar Imager
Authors: Rajagopal, Jayadev K.; Böker, Torsten; Allen, Ronald J.;
Carpenter, Kenneth G.
2003SPIE.4852..652R Altcode:
A number of proposed space missions for high resolution imaging
at wavelengths ranging from IR to UV call for “dilute-aperture”
Fizeau-mode interferometers. We present here details of a software
tool developed for high fidelity simulations of images obtained with
such instruments. We show simulated images from the Stellar Imager, a
mission concept being developed by NASA's GSFC to obtain high-resolution
images of nearby stars in UV-optical wavelengths. Using the simulator,
we study the capability of the proposed SI design to image stellar
surfaces. We use the simulator to explore parameters of image quality
such as resolution and dynamic range, and to evaluate proposed designs
and the feasibility of science goals.

---------------------------------------------------------
Title: Stellar Imager (SI) mission concept
Authors: Carpenter, Kenneth G.; Schrijver, Carolus J.; Lyon, Richard
G.; Mundy, Lee G.; Allen, Ronald J.; Armstrong, J. Thomas; Danchi,
William C.; Karovska, Margarita; Marzouk, Joseph; Mazzuca, Lisa M.;
Mozurkewich, David; Neff, Susan G.; Pauls, Thomas A.; Rajagopal,
Jayadev K.; Solyar, Gregory; Zhang, Xiaolei
2003SPIE.4854..293C Altcode:
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It is designed to
image stars and binaries with sufficient resolution to enable long-term
studies of stellar magnetic activity patterns, for comparison with those
on the sun. It will also support asteroseismology (acoustic imaging) to
probe stellar internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects of
the magnetic fields of stars, the dynamos that generate these fields,
and the internal structure and dynamics of the stars. The ultimate
goal of the mission is to achieve the best-possible forecasting
of solar activity as a driver of climate and space weather on time
scales ranging from months up to decades, and an understanding of the
impact of stellar magnetic activity on life in the Universe. In this
paper we describe the scientific goals of the mission, the performance
requirements needed to address these goals, the "enabling technology"
development efforts being pursued, and the design concepts now under
study for the full mission and a possible pathfinder mission.

---------------------------------------------------------
Title: UMBRAS: a matched occulter and telescope for imaging extrasolar
planets
Authors: Schultz, Alfred B.; Jordan, Ian J.; Kochte, Mark; Fraquelli,
Dorothy A.; Bruhweiler, Fred; Hollis, Jan M.; Carpenter, Kenneth
G.; Lyon, Richard G.; DiSanti, Mike A.; Miskey, Cherie L.; Leitner,
Jesse; Burns, Richard D.; Starin, Scott R.; Rodrigue, Melodi; Fadali,
M. S.; Skelton, Dennis L.; Hart, Helen M.; Hamilton, Forrest C.;
Cheng, Kwang-Ping
2003SPIE.4860...54S Altcode:
We describe a 1-meter space telescope plus free-flying occulter craft
mission that would provide direct imaging and spectroscopic observations
of Jovian and Uranus-sized planets about nearby stars not detectable
by Doppler techniques. The Doppler technique is most sensitive for
the detection of massive, close-in extrasolar planets while the use
of a free-flying occulter would make it possible to image and study
stellar systems with planets comparable to our own Solar System. Such a
mission with a larger telescope has the potential to detect earth-like
planets. Previous studies of free-flying occulters reported advantages
in having the occulting spot outside the telescope compared to a
classical coronagraph onboard a space telescope. Using an external
occulter means light scatter within the telescope is reduced due to
fewer internal obstructions and less light entering the telescope and
the polishing tolerances of the primary mirror and the supporting optics
can be less stringent, thereby providing higher contrast and fainter
detection limits. In this concept, the occulting spot is positioned
over the star by translating the occulter craft, at distances of 1,000
to 15,000 kms from the telescope, on the sky instead of by moving the
telescope. Any source within the telescope field-of-view can be occulted
without moving the telescope. In this paper, we present our current
concept for a 1-m space telescope matched to a free-flying occulter,
the Umbral Missions Blocking Radiating Astronomical Sources (UMBRAS)
space mission. An UMBRAS space mission consists of a Solar Powered Ion
Driven Eclipsing Rover (SPIDER) occulter craft and a matched (apodized)
telescope. The occulter spacecraft would be semi-autonomous, with its
own propulsion systems, internal power (solar cells), communications,
and navigation capability. Spacecraft rendezvous and formation flying
would be achieved with the aid of telescope imaging, RF or laser
ranging, celestial navigation inputs, and formation control algorithms.

---------------------------------------------------------
Title: The Stellar Imager (SI): An Ultra-High Angular Resolution
Ultraviolet/Optical Observatory
Authors: Carpenter, K. G.; Lyon, R. G.; Schrijver, C. J.; Mundy, L.;
Allen, R. J.; Rajagopal, J.
2003ASPC..291..355C Altcode: 2003hslf.conf..355C
No abstract at ADS

---------------------------------------------------------
Title: The Fizeau Interferometer Testbed
Authors: Zhang, Xiaolei; Carpenter, Kenneth G.; Lyon, Richard G.;
Huet, Hubert; Marzouk, Joe; Solyar, Gregory
2002astro.ph.12439Z Altcode:
The Fizeau Interferometer Testbed (FIT) is a collaborative effort
between NASA's Goddard Space Flight Center, the Naval Research
Laboratory, Sigma Space Corporation, and the University of Maryland. The
testbed will be used to explore the principles of and the requirements
for the full, as well as the pathfinder, Stellar Imager mission
concept. It has a long term goal of demonstrating closed-loop control
of a sparse array of numerous articulated mirrors to keep optical
beams in phase and optimize interferometric synthesis imaging. In this
paper we present the optical and data acquisition system design of the
testbed, and discuss the wavefront sensing and control algorithms to
be used. Currently we have completed the initial design and hardware
procurement for the FIT. The assembly and testing of the Testbed will be
underway at Goddard's Instrument Development Lab in the coming months.

---------------------------------------------------------
Title: Steps Toward a Large Space-Based UV/Optical Fizeau
Interferometer: The GSFC Fizeau Interferometer Testbed (FIT)
Authors: Carpenter, K. G.; Lyon, R. G.; Mazzuca, L. M.; Solyar, G.;
Marzouk, J.; Mundy, L. G.; Armstrong, J. T.; Zhang, X.
2002AAS...201.8209C Altcode: 2002BAAS...34.1240C
Goddard Space Flight Center is pursuing the development of
space-based, long-baseline (&gt;0.5km) UV-optical Fizeau imaging
interferometers to enable the next major stride toward very high
angular resolution astronomical observations. This effort includes
the development and operation of the Fizeau Interferometry Testbed
(FIT), in collaboration with the Naval Research Lab/NPOI, Univ. of
MD, and Sigma Space Corporation. The FIT will be used to explore the
principles of and requirements for the Stellar Imager (SI) mission
concept (http://hires.gsfc.nasa.gov/ ~si) and other such Fizeau
Interferometers/Sparse Aperture Telescope missions, leading in the end
to the Planet Imager (PI), which is the ultimate goal of the current
Origins Program. The primary goal of the FIT program is to demonstrate
closed-loop control of mirrors (tip, tilt, piston, translation of
array elements) and the overall system to keep the optical beams in
phase and enable high quality imaging by a many-element (7-30) Fizeau
Interferometric System. The FIT will also be used to assess various
wavefront reconstruction and sensing and image reconstruction algorithms
for utility and accuracy by application to real data generated by the
Testbed. In this paper, we describe the design and goals of the system,
provide a status report on its construction, and note our future
plans. The FIT development is supported by NASA-ROSS/SARA grants to
GSFC, UMD, and NRL and by internal GSFC R&amp;D funds.

---------------------------------------------------------
Title: The Stellar Imager (SI): An UV-Optical Interferometer in Space
Authors: Zhang, X.; Carpenter, K.; Schrijver, C.
2002AAS...200.6102Z Altcode: 2002BAAS...34..744Z
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class mirrors
distributed with a maximum baseline of 0.5 km and providing a resolution
of 60 micro-arcseconds at 1550 A. It will image stars and binaries
with one hundred to one thousand resolution elements on their surfaces
and enable long-term studies of stellar magnetic activity patterns and
their evolution with time, for comparison with those on the sun. It will
also sound their interiors through asteroseismology to image internal
structure, differential rotation, and large-scale circulations. SI will
enable us to understand the various effects of magnetic fields of stars,
the dynamos that generate them, and the internal structure and dynamics
of the stars in which they exist. The ultimate goal is to achieve the
best-possible forecasting of solar activity on times scales ranging
up to decades, and an understanding of the impact of stellar magnetic
activity on life in the Universe. With substantial improvements in
normal-incidence mirror coatings for the EUV, the concept could be
extended into that shorter wavelength regime as well. Fitting naturally
within the NASA long-term time line, SI complements defined missions,
and with them will show us entire other solar systems, from the central
star to their orbiting planets.

---------------------------------------------------------
Title: What Is Happening at Spectral Type F5 in Hyades F Stars?
Authors: Böhm-Vitense, Erika; Robinson, Richard; Carpenter, Kenneth;
Mena-Werth, Jose
2002ApJ...569..941B Altcode:
Aiming at a better understanding of the mechanisms heating the
chromospheres, transition regions, and coronae of cool stars, we study
ultraviolet, low-resolution Hubble Space Telescope/Space Telescope
Imaging Spectrograph spectra of Hyades main-sequence F stars. We
study the B-V dependence(s) of the chromospheric and transition layer
emission line fluxes and their dependences on rotational velocities. We
find that the transition layer emission line fluxes and also those of
strong chromospheric lines decrease steeply between B-V=0.42 and 0.45,
i.e., at spectral type F5, for which the rotational velocities also
decrease steeply. The magnitude of the line-flux decrease increases
for lines of ions with increasing degree of ionization. This shows
that the line-flux decrease is not due to a change in the surface
filling factor but rather due to a change of the relative importance
of different heating mechanisms. For early F stars with B-V&lt;0.42
we find for the transition layer emission lines increasing fluxes
for increasing vsini, indicating magnetohydrodynamic heating. The
vsini dependence is strongest for the high-ionization lines. On
the other hand, the low chromospheric lines show no dependence on
vsini, indicating acoustic shock heating for these layers. This also
contributes to the heating of the transition layers. The Mg II and Ca
II lines show decreasing fluxes for increasing vsini, as long as vsini
is less than ~40 km s-1. The coronal X-ray emission also
decreases for increasing vsini, except for vsini larger than ~100 km
s-1. We have at present no explanation for this behavior. For
late F stars the chromospheric lines show vsini dependences similar to
those observed for early F stars, again indicating acoustic heating
for these layers. We were unable to determine the vsini dependence
of the transition layer lines because of too few single star
targets. The decrease of emission line fluxes at the spectral type
F5, with steeply decreasing vsini, indicates, however, a decreasing
contribution of magnetohydrodynamic heating for the late F stars. The
X-ray emission for the late F stars increases for increasing vsini,
indicating magnetohydrodynamic heating for the coronae of the late F
stars, different from the early F stars. Based on observations with
the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

---------------------------------------------------------
Title: Estimation of Mass-Loss Rates for M Giants from UV Emission
Line Profiles
Authors: Carpenter, K. G.; Robinson, R. D.
2001AAS...199.9205C Altcode: 2001BAAS...33.1441C
The photon-scattering winds of M giants produce absorption features
in the strong chromospheric emission lines. These provide us with an
opportunity to assess important parameters of the wind, including
flow and turbulent velocities, the optical depth of the wind above
the region of photon creation, and the star's mass-loss rate. We
have used the Lamers et al. (1987) Sobolev with Exact Integration
(SEI) radiative transfer code, along with simple models of the outer
atmospheric structure and wind, to determine the wind characteristics of
two M-giant stars, γ Cru (M3.4) and μ Gem (M3IIIab). The SEI code has
the advantage of being computationally fast and allows a great number
of possible wind models to be examined. The analysis procedure involves
specifying wind parameters and then using the program to calculate
line profiles for the Mg II (UV1) lines and a range of unblended Fe II
lines. These lines have a wide range of wind opacities and therefore
probe different heights in the atmosphere. The assumed wind properties
are iterated until the predicted profiles match the observations
over as many lines as possible. We present estimates of the wind
parameters for these stars and offer a comparison to wind properties
previously-derived for low-gravity K stars using the same technique.

---------------------------------------------------------
Title: Free-flying Occulters for Use with Space Telescopes
Authors: Kochte, M.; Schultz, A. B.; Jordan, I.; Hamilton, F.;
Bruhweiler, F.; DiSanti, M. A.; Burns, R. D.; Carpenter, K.; Hollis,
J. M.; Leitner, J.; Lyon, R. G.; Starin, S.; Fadali, M. S.; Rodrigue,
M.; Skelton, D. L.; Hart, H. M.
2001AAS...199.4501K Altcode: 2001BAAS...33Q1367K
We summarize a free-flying occulter proposal that was submitted to NASA
in response to NRA-01-OSS-04. Free-flying occulters in association
with space telescopes have been proposed for nearly four decades to
detect and study extrasolar planets. External occulters reduce the
magnitude differences between a planet and the host star; light scatter
within the telescope is reduced resulting from fewer obstructions and
optical surfaces; and any instrument onboard the telescope, including
spectrometers, can be used to study extrasolar planets. We conclude with
a mission concept for an optimized optical 1-m space telescope with a
small external occulter. Both craft could be launched from a single
launch vehicle and placed in a 1-AU fall-away orbit or at Earth-Sun
L2. Jovian planets around stars within 10 parsecs could be studied,
and a search for sub-Jovian planets around the nearest handful of stars
could be performed. Approximately 80% of the telescope time would be
available for projects not associated with the external occulter such
as gravitational lensing and planetary transit surveys.

---------------------------------------------------------
Title: Goddard High Resolution Spectrograph Observations of NGC 4151
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Snow, M.; Ake, T. B.
2001AJ....121.2999B Altcode:
Goddard High Resolution Spectrograph observations of the nucleus of
the bright, nearby Seyfert galaxy NGC 4151 are presented andbriefly
described.

---------------------------------------------------------
Title: AB Dor in '94. I. Hubble Space Telescope Goddard High
Resolution Spectrogaph Observations of the Quiescent Chromosphere
of an Active Star
Authors: Brandt, J. C.; Heap, S. R.; Walter, F. M.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura,
M.; Leckrone, D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Weymann, R. J.; Norman, D.; Redfield, S.
2001AJ....121.2173B Altcode:
We analyze Hubble Space Telescope/Goddard High Resolution Spectrograph
spectra of AB Doradus, the prototypical, ultrarapidly rotating K
dwarf. We observed chromospheric (Mg II) and transition-region (C
II, Si IV, C IV, and N V) lines periodically throughout the stellar
rotation period and provide a low-dispersion stellar atlas of 78
emission lines. The quiescent line profiles of the chromospheric
and transition-region lines show narrow cores superposed on very
broad wings. The broad wings of the Mg II k and h lines and of
the transition-region lines can be explained by emission from gas
corotating with the star and extending out to near the Keplerian
corotation radius (2.8 stellar radii). While this is not a unique
solution, it is consistent with previous studies of Hα emission,
which are naturally explained by large corotating prominences. We find
no evidence for rotational modulation of the emission-line fluxes. The
density diagnostics suggest that the transition region is formed at
constant pressure, with an electron density of 2-3×1012
cm-3 at a temperature of 3×104 K. The electron
pressure is about 100 times larger than that for the quiet Sun. The
emission-measure distribution shows a minimum between logT=5 and
5.5. The Mg II line exhibits three interstellar absorption components
along the 15 pc line of sight. We identify the lowest velocity component
with the G Cloud, but the other components are not identified with
any interstellar clouds previously detected from other lines of sight.

---------------------------------------------------------
Title: Mg II Emission Lines of Hyades F Stars
Authors: Böhm-Vitense, Erika; Mena-Werth, Jose; Carpenter, Kenneth
G.; Robinson, Richard D.
2001ApJ...550..457B Altcode:
With the Hubble Space Telescope (HST) we have observed Hyades
F stars, using the Space Telescope Imaging Spectrograph (STIS),
in order to get more information about the heating mechanism(s)
for the chromospheres and transition layers and their dependence
on rotation and age. In this paper we study the Mg II lines at 2800
Å. We include earlier observations with the International Ultraviolet
Explorer (IUE) satellite. The Mg II emission lines become observable
for B-V&gt;0.3. The emission line fluxes increase steeply until
B-V~0.40. For single stars there is a steep decrease in flux between
B-V=0.41 and B-V=0.44, similar to the behavior of the Ca II emission
line cores. For larger B-V the Mg II emission line fluxes again
increase, but much more slowly than for the Ca II lines. Generally,
the low point of the emission is reached between B-V=0.43 and B-V=0.45,
i.e., similar to the Ca II emission cores. For the Hyades F stars there
appears to be a difference between the emissions for single stars and
those for binaries. We find that for Hyades stars with surface line
fluxes larger than 106 ergs cm-2 s-1
the emission line fluxes decrease with increasing vsini. For smaller
fluxes they may increase with increasing vsini. We have only three
stars that perhaps show this. We study the flux ratios of the Mg II
k and h lines at 2795.7 and 2802.5 Å in order to determine where
the lines fall on the curve of growth. For the earliest F stars
studied here the ratio is close to 2, as expected for optically thin
lines. Generally, it seems that the optical depths in the line centers
are less than 10. There remain problems in understanding the size of
the line widths. We discuss the interpretation of the Wilson-Bappu
effect. For the Hyades F stars there is a strong dependence of the
line width on the effective temperature. Based on observations with
the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy. Incorporated, under NASA contract NAS5-26555.

---------------------------------------------------------
Title: The Stellar Imager (SI) mission concept
Authors: Carpenter, Kenneth G.; Neff, Susan G.; Schrijver, Carolus J.;
Allen, Ronald J.; Rajagopal, Jay
2001LIACo..36..177C Altcode: 2001fomi.conf..177C
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It will image stars
and binaries with one hundred to one thousand resolution elements on
their surface and enable long-term studies of stellar magnetic activity
patterns and their evolution with time, for comparison with those on
the sun. It will also sound their interiors through asteroseismology
to image internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects
of magnetic fields of stars, the dynamos that generate them, and the
internal structure and dynamics of the stars in which they exist. The
ultimate goal is to achieve the best-possible forecasting of solar
activity on times scales ranging up to decades, and an understanding
of the impact of stellar magnetic activity on astrobiology and
life in the Universe. The road to that goal will revolutionize our
understanding of stars and stellar systems, the building blocks of the
Universe. Fitting naturally within the NASA and ESA long-term time
lines, SI complements defined missions, and with them will show us
entire other solar systems, from the central star to their orbiting
planets. In this paper we will describe the scientific goals of the
mission, the performance requirements needed to address those goals,
and the design concepts now under study.

---------------------------------------------------------
Title: Far-UV Echelle Spectroscopy of Arcturus with HST STIS (CD-ROM
Directory: contribs/ayres)
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.; Bennett, P. D.;
Linsky, J. L.; Carpenter, K. G.; Robinson, R. D.
2001ASPC..223.1079A Altcode: 2001csss...11.1079A
No abstract at ADS

---------------------------------------------------------
Title: Estimation of Mass-Loss Rates from Emission Line Profiles in
the UV Spectra of Cool Stars (CD-ROM Directory: contribs/carpente)
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.
2001ASPC..223.1591C Altcode: 2001csss...11.1591C
No abstract at ADS

---------------------------------------------------------
Title: Coordinated Optical, Radio and EUV Observations of a Flare
on YZ CMi (CD-ROM Directory: contribs/robinson)
Authors: Robinson, R. D.; Airapetian, V.; Slee, O. B.; Mathioudakis,
M.; Carpenter, K. G.
2001ASPC..223.1151R Altcode: 2001csss...11.1151R
No abstract at ADS

---------------------------------------------------------
Title: AB Dor in '94: I. HST/GHRS Observations of the Quiescent
Chromosphere of an Active Star
Authors: Brandt, J. C.; Heap, S. R.; Walter, F. M.; Beaver, E. A.;
Boggess, A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura,
M.; Leckrone, D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.;
Smith, A. M.; Trafton, L. M.; Weymann, R. J.; Norman, D.; Redfield, S.
2000astro.ph.12487B Altcode:
We analyze HST/GHRS spectra of AB Doradus, the prototypical
ultra-rapidly rotating K dwarf. We observed chromospheric (Mg II)
and transition region (C II, Si IV, C IV, and N V) lines periodically
throughout the stellar rotation period, and provide a low dispersion
stellar atlas of 78 emission lines. The quiescent line profiles of the
chromospheric and transition region lines show narrow cores superposed
on very broad wings. The broad wings of the Mg II k &amp; h lines and
of the transition region lines can be explained by emission from gas
co-rotating with the star and extending out to near the Keplerian
co-rotation radius (2.8 stellar radii). While this is not a unique
solution, it is consistent with previous studies of H-alpha emission
that are naturally explained by large co-rotating prominences. We
find no evidence for rotational modulation of the emission line
fluxes. The density diagnostics suggest that the transition region is
formed at constant pressure, with an electron density 2-3 E12 /cm^3
at a temperature of 30,000 K. The electron pressure is about 100 times
larger than that for the quiet Sun. The emission measure distribution
shows a minimum between log(T) = 5 and 5.5. The Mg II line exhibits
three interstellar absorption components along the 15 pc line of
sight. We identify the lowest velocity component with the G cloud,
but the other components are not identified with any interstellar
clouds previously detected from other lines of sight.

---------------------------------------------------------
Title: Ultraviolet Emission Lines in BA and Non-BA Giants
Authors: Böhm-Vitense, Erika; Carpenter, Kenneth G.; Robinson,
Richard D.
2000ApJ...545..992B Altcode:
With the Hubble Space Telescope (HST) and the Goddard High Resolution
Spectrograph we have observed four barium and three weak barium stars
in the ultraviolet spectral region, together with two nonpeculiar giant
standard stars. An additional suspected Ba star was observed with HST
and the Space Telescope Imaging Spectrograph. In the H-R diagram,
three of the observed Ba stars lie on the same evolutionary tracks
as the Hyades giants. Using International Ultraviolet Explorer (IUE)
spectra of previously studied giants together with our HST spectra,
we investigate whether the chromospheric and transition layer
emission-line spectra of the Ba stars are different from those of
nonpeculiar giants and from those of giants with peculiar carbon and/or
nitrogen abundances. Except for the Ba star HD 46407 and the suspected
Ba star HD 65699, the Ba star and mild Ba star emission-line fluxes are,
for a given effective temperature and for a given luminosity, lower
than those for the nonpeculiar giants observed with IUE. In comparison
with the HST-observed standard stars, the C IV λ1550-to-C II λ1335
line flux ratios are smaller, but not necessarily so in comparison
with all IUE-observed nonpeculiar giants. However, the C IV-to-C II
line flux ratios for the Ba stars decrease with increasing carbon
abundances. This shows that the energy balance in the lower transition
layer is influenced by the carbon abundance. The temperature gradient
appears to be smaller in the C II line-emitting region. There does not
seem to be a difference in chromospheric electron densities for the
Ba and non-Ba stars, though this result is rather uncertain. Based on
observations with the NASA/ESA Hubble Space Telescope obtained at the
Space Telescope Science Institute, which is operated by the Association
of Universities for Research in Astronomy, Inc., under NASA contract
NAS 5-26555.

---------------------------------------------------------
Title: The Stellar Imager (SI) Mission Concept
Authors: Carpenter, K. G.; Schrijver, C. J.
2000AAS...197.1410C Altcode: 2000BAAS...32.1426C
The Stellar Imager (SI) is envisioned as a space-based, UV-optical
interferometer composed of 10 or more one-meter class elements
distributed with a maximum baseline of 0.5 km. It will image stars
and binaries with one hundred to one thousand resolution elements on
their surface and enable long-term studies of stellar magnetic activity
patterns and their evolution with time, for comparison with those on
the sun. It will also sound their interiors through asteroseismology
to image internal structure, differential rotation, and large-scale
circulations. SI will enable us to understand the various effects
of magnetic fields of stars, the dynamos that generate them, and the
internal structure and dynamics of the stars in which they exist. The
ultimate goal is to achieve the best-possible forecasting of solar
activity on times scales ranging up to decades, and an understanding of
the impact of stellar magnetic activity on astrobiology and life in the
Universe. The road to that goal will revolutionize our understanding of
stars and stellar systems, the building blocks of the Universe. Fitting
naturally within the NASA long-term time line, SI complements defined
missions, and with them will show us entire other solar systems,
from the central star to their orbiting planets.

---------------------------------------------------------
Title: A Dream of a Mission: Stellar Imager and Seismic Probe
Authors: Carpenter, K. G.; Schrijver, C. J.
2000AAS...196.3207C Altcode: 2000BAAS...32..721C
The Stellar Imager and Seismic Probe (SISP) is a mission to understand
the various effects of magnetic fields of stars, the dynamos that
generate them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best-possible
forecasting of solar activity on times scales ranging up to decades,
and an understanding of the impact of stellar magnetic activity on
astrobiology and life in the Universe. The road to that goal will
revolutionize our understanding of stars and stellar systems, the
building blocks of the Universe. SISP will zoom in on what today
- with few exceptions - we only know as point sources, revealing
processes never before seen, thus providing a tool to astrophysics as
fundamental as the microscope is to the study of life on Earth. SISP
is an ultraviolet aperture-synthesis imager with 8-10 telescopes
with meter-class apertures, and a central hub with focal-plane
instrumentation that allows spectrophotometry in passbands as narrow
as a few Angstroms up to hundreds of Angstroms. SISP will image stars
and binaries with one hundred to one thousand resolution elements
on their surface, and sound their interiors through asteroseismology
to image internal structure, differential rotation, and large-scale
circulations; this will provide accurate knowledge of stellar structure
and evolution and complex transport processes, and will impact numerous
branches of (astro)physics ranging from the Big Bang to the future of
the Universe. Fitting naturally within the NASA long-term time line,
SISP complements defined missions, and with them will show us entire
other solar systems, from the central star to their orbiting planets.

---------------------------------------------------------
Title: A dream of a mission: the stellar imager and seismic probe.
Authors: Schrijver, C. J.; Carpenter, K. G.
2000BAAS...32R.828S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A dream of a mission: the Stellar Imager and Seismic Probe
Authors: Schrijver, C. J.; Carpenter, K. G.
2000SPD....31.0298S Altcode: 2000BAAS...32..828S
The Stellar Imager and Seismic Probe (SISP) is a mission to understand
the various effects of magnetic fields of stars, the dynamos that
generate them, and the internal structure and dynamics of the stars in
which they exist. The ultimate goal is to achieve the best-possible
forecasting of solar activity on times scales ranging up to decades,
and an understanding of the impact of stellar magnetic activity on
astrobiology and life in the Universe. The road to that goal will
revolutionize our understanding of stars and stellar systems, the
building blocks of the Universe. SISP represents an advance in image
detail of several hundred times over the Hubble Space Telescope. SISP
will zoom in on what today - with few exceptions - we only know as
point sources, revealing processes never before seen, thus providing
a tool to astrophysics as fundamental as the microscope is to the
study of life on Earth. SISP is an ultraviolet aperture-synthesis
imager with 8-10 telescopes with meter-class apertures, and a central
hub with focal-plane instrumentation that allows spectrophotometry in
passbands as narrow as a few Angstroms up to hundreds of Angstroms. SISP
will image stars and binaries with one hundred to one thousand
resolution elements on their surface, and sound their interiors through
asteroseismology to image internal structure, differential rotation,
and large-scale circulations; this will provide accurate knowledge
of stellar structure and evolution and complex transport processes,
and will impact numerous branches of (astro)physics ranging from the
Big Bang to the future of the Universe. Fitting naturally within the
NASA long-term time line, SISP complements defined missions, and with
them will show us entire other solar systems, from the central star
to their orbiting planets.

---------------------------------------------------------
Title: Do All BA II Stars Have White Dwarf Companions?
Authors: Böhm-Vitense, Erika; Carpenter, Kenneth; Robinson, Richard;
Ake, Tom; Brown, Jeffery
2000ApJ...533..969B Altcode:
With the Hubble Space Telescope (HST) and the Goddard High Resolution
Spectrograph (GHRS) we have observed four barium stars, three mild
barium stars, and one weak G-band star in the ultraviolet spectral
region. One barium star was observed with HST and the Space Telescope
Imaging Spectrograph (STIS). The aim was to check the hypothesis
that all these peculiar stars have white dwarf (WD) companions,
which at their asymptotic giant branch phase transferred mass with
peculiar element abundances to the present barium and CH peculiar
stars. Assuming that the ultraviolet continua of the cool giants,
including the barium stars, are generated in their chromospheres and
that the relations between the continua and the emission lines created
in the chromospheres and transition layers are similar in field giants
and barium stars, we found that, indeed, most of our target barium and
weak barium stars appear to have excess flux in the UV when compared
to standard giant stars. For most of the stars the excess flux can
be attributed to WD companions with temperatures between 10,000 and
12,000 K, if the WD mass is about 0.6 Msolar. Cooling times
for the WDs were derived from their effective temperatures and model
calculations by M. Wood. The calculated cooling times are longer than
the lifetimes of the barium stars on the giant branch. For our target
stars the mass transfer therefore happened while they were still on
the main sequence. For two of the mild barium stars and one or perhaps
two barium stars the derived cooling times for the WD companions come
out to be longer than the total evolutionary times of the barium stars
as calculated by Schaller et al. If our derivations are correct (the
error bars are rather large) then either evolutionary models with larger
convective overshoot have to be used for the barium stars or the cooling
times of the white dwarfs have to be revised downward. Possibly an
additional (as yet unknown) cooling mechanism has to be considered? The
weak G-band star HD 165634, which has a carbon underabundance of about
a factor of 10, also appears to have a WD companion. We discuss the
implications of this very low carbon abundance. Based on observations
with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope
Science Institute, which is operated by the Association of Universities
for Research in Astronomy. Incorporated, under NASA contract NAS5-26555.

---------------------------------------------------------
Title: Critical Complements: Progress on the Orbit of T Mon
Authors: Evans, N. R.; Carpenter, K.; Robinson, R.; Massa, D.;
Wahlgren, G. M.; Vinkó, J.; Szabados, L.
2000ASPC..203..246E Altcode: 2000IAUCo.176..246E; 2000ilss.conf..246E
A preliminary orbit has been derived for the high luminosity, 27-d
classical Cepheid T Mon. Velocities for the hot companion have been
measured from an HST GHRS spectrum and 3 IUE spectra. The companion
velocities are inconsistent with binary orbital motion and it is
likely that the companion is itself a short period binary. The HST
spectrum also shows that the companion is a chemically peculiar star,
probably magnetic.

---------------------------------------------------------
Title: Winds from Luminous Late-Type Stars. I. The Effects of
Nonlinear Alfvén Waves
Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.; Carpenter,
K.; Davila, J.
2000ApJ...528..965A Altcode:
We present the results of magnetohydrodynamic (MHD) modeling of winds
from luminous late-type stars using a 2.5-dimensional, nonlinear MHD
computer code. We assume that the wind is generated within an initially
hydrostatic atmosphere and is driven by torsional Alfvén waves
generated at the stellar surface. Two cases of atmospheric topology
are considered: case I has longitudinally uniform density distribution
and isotropic radial magnetic field over the stellar surface, and case
II has an isotropic, radial magnetic field with a transverse density
gradient, which we refer to as an “atmospheric hole.” We use the
same set of boundary conditions for both models.The calculations
are designed to model a cool luminous star, for which we assume an
initial hydrostatic pressure scale height of 0.072 R*,
an Alfvén wave speed of 92 km s-1 at the surface, and a
wave period of 76 days, which roughly corresponds with the convective
turnover time. For case I the calculations produce a wind with terminal
velocity of ~22 km s-1 and a mass loss rate comparable to the
expected value of 10-6 Msolar yr-1. For
case II we predict a two-component wind: a fast (25 km s-1)
and relatively dense wind outside of the atmospheric hole and a slow
(15 km s-1), rarefied wind inside of the hole.

---------------------------------------------------------
Title: Toward an Orbit for the High-Luminosity Cepheid T Monocerotis
Authors: Evans, Nancy Remage; Carpenter, Kenneth; Robinson, Richard;
Massa, Derck; Wahlgren, Glenn M.; Vinko, Jozsef; Szabados, Laszlo
1999ApJ...524..379E Altcode:
We have obtained new velocities of the long-period Cepheid T Mon
from the ground and velocities of its hot companion with the Hubble
Space Telescope (HST) and the International Ultraviolet Explorer
(IUE). Although observations do not cover a full orbit, both the
maximum and minimum orbital velocities have now been obtained. We
present a preliminary orbit and discuss the uncertainties in the
orbital parameters. The velocities for the companion appear to be
inconsistent with binary orbital motion, and it is likely that the
companion is itself a binary in a short-period orbit. The HST spectrum
of the companion shows that it is a chemically peculiar star, probably
magnetic. Because it is coupled with the more massive Cepheid, it must
be very close to the zero-age main sequence. The well-determined mass
function from the preliminary orbit implies that the inclination of
the long-period system is close to 90°. Based on observations
made with the NASA/ESA Hubble Space Telescope, obtained at the Space
Telescope Science Institute, which is operated by the Association
of Universities for Research in Astronomy, Inc., under NASA contract
NASA-26555

---------------------------------------------------------
Title: GHRS Observations of Cool, Low-Gravity Stars. V. The Outer
Atmosphere and Wind of the Nearby K Supergiant λ Velorum
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Harper, Graham
M.; Bennett, Philip D.; Brown, Alexander; Mullan, Dermott J.
1999ApJ...521..382C Altcode:
UV spectra of λ Velorum taken with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope are used to probe the
structure of the outer atmospheric layers and wind and to estimate the
mass-loss rate from this K5 Ib-II supergiant. VLA radio observations at
λ=3.6 cm are used to obtain an independent check on the wind velocity
and mass-loss rate inferred from the UV observations. Parameters
of the chromospheric structure are estimated from measurements of
UV line widths, positions, and fluxes and from the UV continuum flux
distribution. The ratios of optically thin C II] emission lines indicate
a mean chromospheric electron density of logNe~8.9+/-0.2
cm-3. The profiles of these lines indicate a chromospheric
turbulence (v0~25-36 km s-1), which greatly
exceeds that seen in either the photosphere or wind. The centroids
of optically thin emission lines of Fe II and of the emission
wings of self-reversed Fe II lines indicate that they are formed in
plasma approximately at rest with respect to the photosphere of the
star. This suggests that the acceleration of the wind occurs above
the chromospheric regions in which these emission line photons are
created. The UV continuum detected by the GHRS clearly traces the
mean flux-formation temperature as it increases with height in the
chromosphere from a well-defined temperature minimum of 3200 K up to
about 4600 K. Emission seen in lines of C III] and Si III] provides
evidence of material at higher than chromospheric temperatures in the
outer atmosphere of this noncoronal star. The photon-scattering wind
produces self-reversals in the strong chromospheric emission lines,
which allow us to probe the velocity field of the wind. The velocities
to which these self-absorptions extend increase with intrinsic line
strength, and thus height in the wind, and therefore directly map
the wind acceleration. The width and shape of these self-absorptions
reflect a wind turbulence of ~9-21 km s-1. We further
characterize the wind by comparing the observations with synthetic
profiles generated with the Lamers et al. Sobolev with Exact Integration
(SEI) radiative transfer code, assuming simple models of the outer
atmospheric structure. These comparisons indicate that the wind in
1994 can be described by a model with a wind acceleration parameter
β~0.9, a terminal velocity of 29-33 km s-1, and a mass-loss
rate~3×10-9 Msolar yr-1. Modeling
of the 3.6 cm radio flux observed in 1997 suggests a more slowly
accelerating wind (higher β) and/or a higher mass-loss rate than
inferred from the UV line profiles. These differences may be due to
temporal variations in the wind or from limitations in one or both
of the models. The discrepancy is currently under investigation. 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: STIS UV Atlas of the Red Giant Arcturus(1)
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.; Bennett, P. D.;
Linsky, J. L.; Carpenter, K. G.; Robinson, R. D.
1999AAS...194.6701A Altcode: 1999BAAS...31..930A
The Space Telescope Imaging Spectrograph (STIS) conducted a series
of observations of the archetype “noncoronal” red giant Arcturus
(HD 124897; alpha Boo; K1 III) on 24 August 1998, 17--23 UT. The STIS
program was the result of a failed cycle 5 pointing, which could not
be rescheduled during the abbreviated cycle 6, and was carried over
to cycle 7. Three grating settings---E230H (t_exp= 1340 s), E230M
(2493 s), and E140M (5208 s)---covered the ultraviolet spectrum
from 1150--2850 Angstroms, at resolutions between R ~ 4*E(4) -
1*E(5) , with essentially no gaps. The resulting spectrograms are
stunning. The resolution is very high, as is the S/N; the spectral
coverage is broad and comprehensive. The far-UV interval (1150--1700
Angstroms) is a rich emission line spectrum, dominated by the broad
resonance transitions of atomic hydrogen (lambda 1215) and oxygen
(lambda 1305 triplet). There are numerous narrow emissions, mostly
from low-excitation species such as Si I, Fe II, and fluoresced bands
of carbon monoxide. Surprisingly, high-excitation species---Si IV
(lambda 1393: 6*E(4) K) and C IV (lambda 1548: 1*E(5) K)---are present
as well (as seen in the earlier “failed” GHRS spectra). The mid-UV
(1700--2600 Angstroms) shows additional emission lines, particularly [C
II] and [Si II] in the 2325 Angstroms region; the photospheric continuum
rises strongly toward the longer wavelengths. The 2600--2850 Angstroms
interval is mostly a photospheric absorption spectrum, although the
bright chromospheric emission doublet of Mg II lords over the 2800
Angstroms region. We present a comprehensive spectral atlas based on
our reductions of the STIS echellograms. We discuss the processing
strategies, line identifications, and some of the preliminary results
from our analysis of this windy, noncoronal giant. (1) This work was
supported by grants GO-06066.01-94A from STScI, and NAG5-3226 from
NASA. Observations were from the NASA/ESA HST, collected at the STScI,
operated by AURA, under contract NAS5-26555.

---------------------------------------------------------
Title: A Search for Microflaring Activity on DME Flare
Stars. II. Observations of YZ Canis Minoris
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
1999ApJ...516..916R Altcode:
We report on time-series photometric observations of the dM4.5e flare
star YZ Canis Minoris obtained in 1993 November with the High Speed
Photometer on board the Hubble Space Telescope. The data consist of five
30 minute time sequences with a sampling rate of 0.01 s that were taken
through the F240W filter (centered at 240 nm with an 80 nm width). At
these wavelengths the stellar photospheric background is small,
so relatively small flares can be detected. The observations show a
stellar background of 120 counts s-1 on which are superposed
54 flare events ranging in integrated flux from 2.0×1028
to 3.0×1030 ergs, as well as longer term variations with an
amplitude of up to 50% of the average continuum intensity and timescales
ranging from several minutes to hours. A statistical analysis of this
background suggests that it may be composed of unresolved microflaring
activity that has an energy distribution considerably steeper than
that deduced for the larger flare events. This is consistent with
previous observations as well as the self-organized criticality and
reconnecting current sheet flare theories. These results are compared
with data from the dM8e flare star CN Leonis, which was obtained
earlier with the same experimental setup. CN Leo has both a smaller
stellar background and a lower flare occurrence rate than YZ CMi. The
fact that CN Leo also has a quiescent X-ray flux that is less than
10% of the YZ CMi emission suggests a link between chromospheric and
coronal heating. 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 NAS5-26555.

---------------------------------------------------------
Title: A Goddard High Resolution Spectrograph Atlas of Echelle
Observations of the HGMN Star chi LUPI
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess,
A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.;
Leckrone, D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith,
A. M.; Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Proffitt, C. R.;
Wahlgren, G. M.; Johansson, S. G.; Nilsson, H.; Brage, T.; Snow, M.;
Ake, T. B.
1999AJ....117.1505B Altcode:
Observations of the ultra-sharp-lined, chemically peculiar star chi
Lupi taken by the Goddard High Resolution Spectrograph in echelle mode
are presented. Thirty-six intervals of the spectral region between
1249 and 2688 Å are covered with resolving powers in the range
75,000-93,000. Line identifications are provided, and the observed
spectra are compared with synthetic spectra calculated using the
SYNTHE program and associated line lists with changes to the line
lists. The significance of these spectra for the chi Lupi Pathfinder
Project and the closely related atomic physics effort is discussed in
a companion paper.

---------------------------------------------------------
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: Echelle Spectroscopy of Interstellar Absorption toward MU
Columbae with the Goddard High Resolution Spectrograph
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Howk, J. C.; Snow,
M.; Ake, T. B.; Sembach, K. R.
1999AJ....117..400B Altcode:
Goddard High Resolution Spectrograph echelle-mode observations of
the interstellar absorption lines of Mg II, Si IV, C IV, and N V
toward mu Columbae (HD 38666) are presented. The observations have a
spectral resolution of 3.5 km s^-1 and signal-to-noise ratios (S/Ns)
of 20-200. The mu Col sight line (l=237.3d, b=-27.1d, d=0.40 kpc,
z=-0.18 kpc) extends though the Local Bubble and the warm neutral,
warm ionized, and hot ionized phases of the interstellar medium
(ISM). The high-ionization column densities toward mu Col are
log N(Si IV)=12.16+/-0.05, log N(C IV)=12.88+/-0.02, and logN(N
V)=11.8-12.3. Profile fits to Copernicus satellite measures of O VI
absorption toward mu Col yield log N(O VI)=13.82+/-0.01 and b=38.7
km s^-1. This implies N(C IV)/N(O VI)=0.11+/-0.01, which is typical
of the values found for the hot ISM of the Galactic disk. The O VI
profile is twice as broad as the C IV and N V profiles, even though
these species have roughly similar average velocities. Some of the C
IV, N V, and O VI absorption toward mu Col may occur at the interface
of the Local Cloud and Local Bubble, although additional contributions
to these ions probably also occur in more distant gas along the sight
line. A substantial part of the Si IV absorption likely arises in warm
photoionized gas in an H II region surrounding mu Col. The profile
width differences among the high-ionization lines of C IV, N V, and
O VI could be produced if the line of sight passes through a highly
evolved supernova remnant. The observations for mu Col and for other
stars observed at high resolution with the GHRS reveal that multiple
gas types (warm and hot) contribute to the absorption by the highly
ionized atoms along both nearby and distant sight lines. Disentangling
the relative contributions from the different gas types requires
high-resolution and high-S/N observations. The Mg II observations,
combined with a solar Mg reference abundance, imply that the Mg
depletion toward mu Col is -0.31 dex. As observed for other sight
lines through the warm neutral medium, the gas-phase observations of
Mg, when combined with results for Fe and Si, suggest that Mg and Fe
are more deficient from the gas phase than one would expect if these
elements are only contained in silicate dust grains.

---------------------------------------------------------
Title: Winds and mass-loss from evolved, low-gravity cool stars.
Authors: Carpenter, Kenneth G.; Robinson, Richard D.
1999NewAR..43..471C Altcode:
We summarize results from several programs utilizing the Goddard High
Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) to
study winds and mass-loss from evolved, low-gravity cool stars. We have
found that: (i) the photons for thermally and fluorescently excited
UV emission lines are created below the region of wind acceleration,
(ii) the self-reversals in optically thick emission lines indicate an
outflowing wind with mean velocities of 9-25 km/s, (iii) the profiles
of optically thin emission lines indicate a mean chromospheric
macroturbulence of 24-35 km/s, anisotropically distributed along
the radial-tangential directions, (iv) significant emission from
hot material (≈10 5 K) is seen in both non-coronal and
hybrid stars to the right of the Linsky-Haisch dividing line, (v)
the weakness of Fe II emission lines in the carbon stars, combined
with the presence of the Fe I 2807 Å feature only in carbon stars,
suggests that the ionization fraction of iron is significantly lower in
the outer atmospheres of carbon stars than in O-rich stars, and (vi)
Fe II line profile variations indicate changes in mass-loss rate and
wind opacity on a timescale of several years in two typical late-type,
low-gravity stars.

---------------------------------------------------------
Title: The outer atmosphere of Tau - II. Fluorescent lines
Authors: McMurry, A. D.; Jordan, C.; Carpenter, K. G.
1999MNRAS.302...48M Altcode:
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to observe α Tau (K5 III). The resulting
spectra contain many sharp fluorescent lines. Most of these have been
identified as lines of Fe ii, Ca ii and H2, radiatively
excited by H Lyα. The chromospheric model developed in an accompanying
paper has been used to calculate the fluxes in these lines. The Ca ii
lines have been modelled with a full radiative transfer calculation,
but the Fe ii and H2 systems are more complex and, for
these, a simpler calculation has been made. Overall, the trend in the
Fe ii line fluxes provides evidence for a multicomponent model of the
atmosphere, a chromosphere with intrusions of hotter material or vice
versa. The hotter material could be in shocks propagating through
the chromosphere. Comparisons of the observed and calculated fluxes
of individual lines of Fe ii show that some atomic data need to be
improved. The analysis of the H2 lines is restricted by
a lack of suitable molecular data. The two observed Ca ii lines are
reproduced to within a factor of 2.

---------------------------------------------------------
Title: Estimation of Mass-Loss Rates from Emission Line Profiles in
the UV Spectra of Cool Stars
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.
1999STIN...0027505C Altcode:
The photon-scattering winds of cool, low-gravity stars (K-M giants and
supergiants) produce absorption features in the strong chromospheric
emission lines. This provides us with an opportunity to assess important
parameters of the wind, including flow and turbulent velocities,
the optical depth of the wind above the region of photon creation,
and the star's mass-loss rate. We have used the Lamers et al. Sobolev
with Exact Integration (SEI) radiative transfer code along with simple
models of the outer atmospheric structure to compute synthetic line
profiles for comparison with the observed line profiles. The SEI
code has the advantage of being computationally fast and allows a
great number of possible wind models to be examined. We therefore
use it here to obtain initial first-order estimates of the wind
parameters. More sophisticated, but more time-consuming and resource
intensive calculations will be performed at a later date, using the
SEI-deduced wind parameters as a starting point. A comparison of
the profiles over a range of wind velocity laws, turbulence values,
and line opacities allows us to constrain the wind parameters,
and to estimate the mass-loss rates. We have applied this analysis
technique (using lines of Mg II, 0 I, and Fe II) so far to four stars:
the normal K5-giant alpha Tau, the hybrid K-giant gamma Dra, the K5
supergiant lambda Vel, and the M-giant gamma Cru. We present in this
paper a description of the technique, including the assumptions which
go into its use, an assessment of its robustness, and the results of
our analysis.

---------------------------------------------------------
Title: The Chromosphere, Wind, and Mass-Loss Rate of lambda Velorum
(K5 Ib) as Revealed by UV Emission Line Profiles
Authors: Carpenter, K. G.; Robinson, R. D.; Harper, G. M.; Bennett,
P. D.; Brown, A.; Mullan, D. J.
1998AAS...193.4502C Altcode: 1998BAAS...30Q1317C
The Goddard High Resolution Spectrograph (GHRS) on the HST has been
used to acquire high-quality UV spectra of the nearby K-supergiant
lambda Velorum. These spectra contain a wide variety of chromospheric
emission lines, many of which are self-reversed by wind absorption,
and thus allow us to probe the structure of both the chromosphere
and wind. The observed line widths, positions, and fluxes indicate a
chromosphere with a mean log n_e ~ 8.9 +/- -0.2 cm(-3) , a turbulence
(indicated by line cores with ~ 25 km s(-1) Doppler widths) greatly
in excess of the photospheric value, and no general systematic flows
(i.e. the wind acceleration appears to occur above the region of
photon creation). We compare synthetic Fe II line profiles from the
approximate Lamers et al. (1987) Sobelev with Exact Integration (SEI)
method, and from an exact comoving frame CRD calculation, with the
observations. The width and shape of the wind self-absorptions implies
a terminal velocity of 29--33 km s(-1) , and a wind turbulence of ~
9-21 km s(-1) . We find that the wind in the 1994 GHRS observations
can be described by a model with an acceleration parameter beta ~ 0.9
and a mass-loss rate of ~ 3 x 10(-9) Msun yr(-1) . However,
this model is not consistent with the VLA 3.6 cm radio continuum flux
observed in 1997.

---------------------------------------------------------
Title: The Mass of the Cepheid Binary V636 Scorpii
Authors: Böhm-Vitense, E.; Evans, N. R.; Carpenter, K.; Albrow,
Michael D.; Cottrell, P. L.; Robinson, R.; Beck-Winchatz, B.
1998ApJ...505..903B Altcode:
The mass-luminosity relation for Cepheids depends on the degree of
mixing in their main-sequence progenitors. Masses of Cepheids can be
inferred by using different aspects of pulsation theory. These methods
have in the past led to diverging results, showing that something was
wrong in either evolution theory or pulsation theory or both. For some
binary Cepheids dynamical masses, which are independent of pulsation and
evolution theories, can be determined. V636 Sco is one of a handful of
Cepheid binaries whose companions are bright enough in the ultraviolet
that orbital radial velocities can be measured. We have here attempted
to determine the radial velocity of the companion V636 Sco B to the
Cepheid V636 Sco A by means of two Hubble Space Telescope (HST) spectra
taken at phases of minimum and maximum Cepheid orbital velocities. The
ratio of the orbital velocity of the companion and the Cepheid (which
is the inverse of their mass ratio) came out to be 1.25 +/- 0.17. V636
Sco B has a spectral type B9.5 V, for which we expect a stellar mass
of 2.5 M⊙. For the Cepheid we thus determine a mass
of 3.1 +/- 0.4 M⊙, which is surprisingly low. If true,
such a low mass would indicate an extremely large amount of excess
mixing, which is very unlikely. We discuss the likely possibility
that V636 Sco B may itself be a binary with an unseen secondary,
in which case the mass derived from the two measurements discussed
above is not correct. Although the error limits for the mass of each
Cepheid are rather large, the combined mass-luminosity relation for
all Cepheids studied by us so far by means of HST spectra indicates
excess mixing corresponding to core convective overshoot by 0.25 to
about 0.5 pressure scale height in the main-sequence progenitors of
the Cepheids. Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NASS-26555.

---------------------------------------------------------
Title: Toward a Mass for the High Luminosity Cepheid T MON
Authors: Evans, Nancy Remage; Robinson, Richard D.; Carpenter,
Kenneth G.; Vinko, Jozsef; Massa, Derck; Wahlgren, Glenn M.
1998AAS...192.8204E Altcode: 1998BAAS...30.1155E
The long period (27(d) ) Cepheid T Mon was shown by Coulson (1983,
MNRAS, 203, 925) to have orbital motion. A full orbit has not yet been
observed since the first velocities nearly a century ago. However, the
ratio of the orbital velocity changes during the last decade provide the
mass ratio between the Cepheid and its hot companion. We have obtained
new ground-based velocities of the Cepheid which constrain the orbital
velocity amplitude. To measure the companion velocities, we have IUE
high resolution spectra and also a Hubble Space Telescope Goddard High
Resolution Spectrograph spectrum (1840 to 1880 Angstroms). Use of the
new data to constrain the mass of the Cepheid will be discussed.

---------------------------------------------------------
Title: Goddard High-Resolution Spectrograph Observations of Cool
Low-Gravity Stars. IV. A Comparison of the K5 III stars α Tauri
and γ Draconis
Authors: Robinson, Richard D.; Carpenter, Kenneth G.; Brown, Alexander
1998ApJ...503..396R Altcode:
The Goddard High-Resolution Spectrograph (GHRS) has observed the K5 III
star α Tau in the 2330 Å region on three separate occasions. These
spectra show marked changes with time, with the UV continuum varying
by a factor of 2, and with the emission lines changing in flux by 30%
or more, with the amount of change dependent upon the opacity of the
line. The variations suggests a restructuring of the atmosphere rather
than simply a change in the surface area covered by chromospheric
material. Surprisingly, there was no detectable change in the
chromospheric turbulence on timescales of hours or years. On average,
the lower part of the atmosphere was found to be fairly static, with
a slight infall of 1-2 km s-1. At higher altitudes, probed
by observation of the stronger Fe II lines as well as of the O I (UV 2)
and Mg II (UV 1) resonance lines, there is evidence for the acceleration
of a slow wind, similar to that seen in the M giants γ Cru and μ
Gem. This wind is much less massive than for the later type giants,
however, since its effects are seen in only the most optically thick
of the Fe II lines. Comparison of the α Tau observations with similar
data for the K5 III hybrid star γ Dra shows remarkable similarity in
the photosphere and lower chromosphere. Both stars have pronounced
UV continua, identical turbulences and chromospheric densities, and
very similar line fluxes and profiles for all lines formed in the
lower chromosphere, including C II], Co I, Si II], and Fe II. A deep
exposure near 1500 Å also shows the first evidence for hot plasma
in the atmosphere of α Tau through the detection of the C IV (UV 1)
doublet with a surface flux about 30% of that observed in γ Dra. Most
of the evidence for the stellar wind is in the Mg II (UV 1) and O I
(UV 2) resonance lines. Modeling these lines using the Sobolev with
Exact Integration (SEI) radiative transfer code shows that the wind in
γ Dra accelerates faster and reaches a higher terminal velocity than
does the wind in α Tau. However, the wind turbulent velocity in γ Dra
is only about one-third of the value seen in α Tau. We conclude that
the observations support the suggestion by Judge &amp; Stencel that the
processes that heat the chromosphere are distinct from those that drive
the stellar winds. 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: An Ultraviolet Spectral Atlas of 10 Lacertae Obtained with
the Goddard High Resolution Spectrograph on the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess,
A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.;
Leckrone, D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith,
A. M.; Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Snow, M.; Ake,
T. B.; Hogen, R. H.
1998AJ....116..941B Altcode:
Observations of the narrow-lined O-type star 10 Lacertae taken with the
Goddard High Resolution Spectrograph in 1992 November are presented. The
spectra cover the wavelength range 1181-1777 Å with a resolution of
15 km s^-1 and signal-to-noise ratio greater than 100:1. Absorption
lines arising in the interstellar medium, the photosphere, and the
stellar wind are identified and discussed.

---------------------------------------------------------
Title: Large Variations in the Winds of Single Cool Giants: λ
Velorum and γ Crucis
Authors: Mullan, D. J.; Carpenter, K. G.; Robinson, R. D.
1998ApJ...495..927M Altcode:
UV spectra of the “noncoronal” single K supergiant λ Vel and of
the single M giant γ Cru obtained with IUE and the Hubble Space
Telescope at various epochs indicate that the profiles of many lines
formed in the wind exhibit striking alterations in shape with time. We
parameterize the wind profiles in terms of an empirical optical depth
τemp by reflecting the red wing about line center and
comparing the reflected intensity with that of the blue wing. In the λ
Vel wind the terminal velocity v∞ was found to be close
to 40 km s-1 in 1978, 1982, and 1994, but was at least 20
km s-1 greater in 1990. The faster wind in 1990 also had
a total optical depth that was a factor of 2-6 times greater than at
the other epochs. 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,
and on observations with the International Ultraviolet Explorer.

---------------------------------------------------------
Title: Classical Cepheid Masses: U Aquilae
Authors: Evans, Nancy Remage; Böhm-Vitense, Erika; Carpenter, Kenneth;
Beck-Winchatz, Bernhard; Robinson, Richard
1998ApJ...494..768E Altcode:
We have obtained medium-resolution spectra (λ/Δλ ~ 20,000) of the hot
binary companion to the classical Cepheid U Aql with the Goddard High
Resolution Spectrograph on the Hubble Space Telescope (HST). These have
been used to determine the orbital velocity amplitude. Combining this
with the orbital velocity amplitude of the Cepheid from the ground-based
orbit and the mass of the companion inferred from its spectral type, we
measure a mass of the Cepheid of 5.1 +/- 0.7 M⊙. We discuss
the full sample of Cepheids for which we have determined masses with HST
(S Mus, V350 Sgr, Y Car, and U Aql) and also SU Cyg (mass from IUE). The
HST masses are in agreement with the luminosities predicted by recent
evolutionary tracks with moderate overshoot. This comparison, however,
may be altered by reassessment of Cepheid distances based on Hipparcos
parallaxes. Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NASA-26555.

---------------------------------------------------------
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. 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. 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. 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. 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 Goddard High Resolution Spectrograph: Post-COSTAR
Characteristics
Authors: Robinson, R. D.; Ake, T. B.; Lindler, D. J.; Heap, S. R.;
Carpenter, K. G.; Leckrone, D. S.; Maran, S. P.; Smith, A. M.; Brandt,
J. C.; Beaver, E. A.; Boggess, A.; Ebbets, D. C.; Hutchings, J. B.;
Jura, M.; Linsky, J. L.; Savage, B. D.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.
1998PASP..110...68R Altcode:
We review changes to the characteristics of the Goddard High Resolution
Spectrograph (GHRS) which resulted from the installation of the
Corrective Optics Space Telescope Axial Replacement (COSTAR) on the
Hubble Space Telescope. The introduction of two new optical elements
into the light path altered the spectral distribution of the light,
decreasing the amount of light striking the instrument by about 30%
at wavelengths greater than 1200 Å and effectively eliminated all
radiation at wavelengths less than 1130 Å. However, at the longer
wavelengths the improved focus offset this loss when the Large Science
Aperture (LSA) was used and increased the overall throughput of the
Small Science Aperture (SSA) by a factor of 2. The improved focus also
enhanced the spectral resolution of LSA observations and improved the
ability of the instrument to observe in crowded fields.

---------------------------------------------------------
Title: The Mass of the Classical Cepheid V350 SGR
Authors: Evans, N. R.; Bohm-Vitense, E.; Beck-Winchatz, B.; Carpenter,
K.; Robinson, R.
1998ASPC..143..313E Altcode: 1998sigh.conf..313E
No abstract at ADS

---------------------------------------------------------
Title: The Structure of the Outer Atmosphere and Wind of lambda Vel
Authors: Carpenter, Kenneth G.
1998IAUS..191P.206C Altcode:
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope (HST) has been used to acquire high-quality UV spectra of the
nearby K-supergiant lambda Vel, a star most likely in an evolutionary
stage either immediately preceeding or just entering the AGB. These
spectra contain a wide variety of chromospheric emission lines, as
well as a strong chromospheric continuum, and thus allow us to probe
conditions in the the atmospheric region within which the stellar wind
and associated mass-loss are initiated. In addition, the profiles of
many of these emission lines are influenced by absorption occurring
within the wind and are thus good diagnostics of the radial structure of
that wind. Comparison of synthetic and observed spectra allows estimates
of the wind turbulence, acceleration, opacity, and mass-loss rate. We
present a summary of our analysis of these spectra, including: 1)
measurements of temperature, turbulence, and flow velocity versus height
in the chromosphere and wind, and 2) estimates of the mass-loss rate. It
is our hope that these observations will provide powerfull constraints
on theoretical models of chromospheric heating, wind acceleration,
and mass-loss in this and other red giant and supergiant stars.

---------------------------------------------------------
Title: The Mass of the Beat Cepheid Y Carinae
Authors: Bohm-Vitense, E.; Beck-Winchatz, B.; Evans, N. R.; Carpenter,
K. G.; Robinson, R.
1998ASPC..143..317B Altcode: 1998sigh.conf..317B
No abstract at ADS

---------------------------------------------------------
Title: Fluorescence in the Chromosphere of alpha Tau (K5 III)
Authors: McMurry, A. D.; Jordan, C.; Carpenter, K. G.; Robinson, R. D.
1998ASPC..154.1293M Altcode: 1998csss...10.1293M
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to obtain spectra of alpha Tau covering many
parts of the uv spectrum between 1200AA and 2000AA. Here we concentrate
on the region between 1320AA and 1390AA, which is covered by 2 medium
resolution exposures. Most of the lines appearing in these spectra have
been identified, including 2 bands of fluorescent CO lines. Preliminary
modelling of these CO lines has been carried out, and the results are
compared with the observations.

---------------------------------------------------------
Title: The Mass of the Classical Cepheid S MUSCAE
Authors: Evans, N. R.; Bohm-Vitense, E.; Beck-Winchatz, B.; Carpenter,
K.; Robinson, R.
1998ASPC..143..309E Altcode: 1998sigh.conf..309E
No abstract at ADS

---------------------------------------------------------
Title: The Dynamical and Beat Masses of the Beat Cepheid Y Carinae
Authors: Bohm-Vitense, E.; Evans, N. R.; Carpenter, K.; Winchatz,
B. Beck-; Morgan, S.; Robinson, R.
1998ASPC..135..280B Altcode: 1998hcsp.conf..280B
The mass-luminosity relation for Cepheids depends on the degree
of excess mixing in their main sequence progenitors. The mass
determination for Cepheids with their known luminosities therefore
determines the degree of excess mixing in massive main sequence
stars. We have determined the dynamical mass of several Cepheids with
blue companions. Here we discuss the beat Cepheid Y Carinae. By means
of HST, GHRS spectra we measured the radial velocity of the B9.5 V
companion Y Car B at phases near minimum and maximum orbital radial
velocities. The orbital velocity amplitude ratio between the Cepheid
and the hot companion and thereby the mass ratio comes out to be 1.51
0.5, leading to a mass of 3.8 1 1.2 solar masses. Taking the 3.8 solar
masses at face value this indicates excess mixing corresponding to
convective overshoot by about 1 pressure scale height, (see Bertelli et
al.1986), but the error limits are too large for a firm conclusion. The
beat masses, determined from the period ratios for the beat Cepheids,
have puzzled astronomers for a long time (see Cox 1980) because they
came out around 1 to 2 solar masses, when the Cox-Tabor opacities
were used for the model calculations. Moskalik et al.(1992) showed
that beat masses around 4 to 5 solar masses can now be derived, if
the new OPAL opacities are used instead. With the determination of
the dynamical mass for Y Car A we can now check the validity of the
OPAL opacities more quantitatively than was possible before. Using the
model calculations incorporating the OPAL opacities, and the observed
effective temperature of Y Carinae we determine for its beat mass a
possible range of 3.75 &lt; M/Ms &lt; 4.0, in very good agreement with
the dynamical mass. This supports the validity of the OPAL opacities,
and also supports the conclusion about the high degree of excess mixing
in the main sequence progenitor of Y Carinae A.

---------------------------------------------------------
Title: Cool Stars
Authors: Carpenter, K. G.
1998ASPC..143...67C Altcode: 1998sigh.conf...67C
No abstract at ADS

---------------------------------------------------------
Title: Winds and Mass-Loss from Evolved, Low-Gravity Cool Stars
Authors: Carpenter, K. G.; Robinson, R. D.
1998HiA....11..378C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Searching for the Cause of Hybrid Star Activity
Authors: Robinson, Richard D.; Carpenter, Kenneth G.; Brown, Alexander
1998ASPC..154.1307R Altcode: 1998csss...10.1307R
UV spectra for a wide range of chromospheric diagnostics have been
obtained for the non-coronal giant alpha Tau and the `hybrid' star
gamma Dra using the Goddard High Resolution Spectrograph. These stars
have very similar spectral types and are very close to one another in
mass, luminosity, size, effective temperature and gravity. A detailed
comparison shows that the photosphere and chromosphere of the stars
are very similar. The two stars show the same level of UV continuum
emission and chromospheric turbulence and have Fe 2 emission profiles
which are nearly identical. The amount of transition region plasma,
as measured by the C 4 surface flux, is also nearly the same. The winds
of these two stars, however, are significantly different. Preliminary
models based on the O 1 (UV 2) and Mg 2 (UV 1) profiles show that
the wind for alpha Tau has a terminal velocity of ~30 km s^{-1} and
a much slower acceleration than the wind of gamma Dra, which has a
terminal velocity of ~65 km s^{-1}. However, despite the different wind
properties, the mass loss rate from these two stars is very similar.

---------------------------------------------------------
Title: Two-Component Winds from Luminous Late-Type Stars
Authors: Airapetian, V. S.; Offman, L.; Robinson, R.; Carpenter, K.;
Davila, J.
1998BAAS...30..760A Altcode:
We present the results of a magnetohydrodynamic (MHD) simulation
of winds from luminous late-type stars using a 2.5D, non-linear MHD
computer code. In this simulation we assume that the wind is generated
within a hydrostatic atmosphere with an initial isothermal pressure
scale height of 0.072 Rstar and a radial magnetic field. We
also assume a transverse density gradient which we we refer to as a
“chromospheric hole”. Tortional Alfven waves are generated at the
stellar surface by a forcing function having a single frequency, which
is comparable to the turn-over frequency of convective cells in giant
stars. To ensure that we are accurately assessing the terminal velocity
of the wind, we carried out the calculations to a height of 20 stellar
radii and a time period of more than 180 Alfven transit times, which
ensures that a steady state has been reached. In the higher density
(low Alfven velocity) regions outside of the “chromospheric hole” the
Alfven waves are freely propagating. Ponderomotive forces associated
with these waves drive radial, compressive motions and contribute to
stellar wind acceleration. The compressive motions then excite slow
magnetosonic waves which non-linearly steepen into solitary waves that
propagate on top of a background flow similar to the case of solar
coronal holes. This produces a fast (40-80 km/s) and relatively dense
component of the wind. In the lower density “chromospheric hole”
region the Alfven waves are strongly reflected and produce an outflow
with both radial and azimuthal velocities which are ~ 10% of the local
Alfven speed. This component of the wind is slow ( ~ 10-30 km/s) and
less dense than the wind initiated outside of the hole. Depending on
the magnetic topology in the atmosphere of a luminous late - type
star, we may therefore expect either one (fast) or two components
to the wind. Our results are consistent with recent observations of
two discrete components to the wind in the K5 III hybrid star gamma
Dra. These components were detected in the Mg II h and k resonance lines
and had velocities of 67 and 30 km/s, with the higher velocity component
having a mass loss rate which is 10 times that of the slower speed wind.

---------------------------------------------------------
Title: Atmospheric Dynamics of Luminous Late-Type Stars
Authors: Airapetian, V. S.; Ofman, L.; Robinson, R. D.; Carpenter,
K.; Davila, J.
1998ASPC..154.1569A Altcode: 1998csss...10.1569A
We present first results of magnetohydrodynamic (MHD) calculations of
winds from luminous late-type stars using an existing, 2.5D, non-linear
MHD code recently developed by Ofman &amp; Davila (e.g., Ofman &amp;
Davila 1997). We assume that the wind is initiated in a hydrostatic
atmosphere with an isothermal pressure scale height of 0.072 R* and a
“chromospheric hole” modeled by a transverse density structure and
a radial magnetic field. To ensure that we are accurately assessing
the terminal velocity of the wind, we carried out the calculations
to a height of 20 stellar radii. We find that in the higher density
(low Alfven velocity) regions outside of the “chromospheric hole” the
Alfven waves are freely propagating. Ponderomotive forces associated
with these waves drive radial, compressive motions and contribute to
stellar wind acceleration. The compressive motions then excite slow
magnetosonic waves which non-linearly steepen into solitary waves that
propagate on top of a background flow. This situation is similar to
solar coronal hole models. In the lower density “chromospheric hole”
region the Alfven wave are strongly reflected, and produce a substantial
outflow, with both radial and azimuthal velocities approaching the
local Alfven speed. Our results are in qualitative agreement with
observational signatures of winds in cool, luminous late-type stars.

---------------------------------------------------------
Title: HST Observations of Carbon Stars
Authors: Carpenter, Kenneth G.; Robinson, R. D.; Johnson, H. R.
1998ASPC..154.1578C Altcode: 1998csss...10.1578C
Ultraviolet spectra obtained with the Goddard High Resolution
Spectrograph (GHRS) on the HST of the carbon stars TX Psc, TW Hor,
and UU Aur are presented and compared with each other and with spectra
of the oxygen-rich cool giants mu Gem and 30 Her. For TX Psc, we
discuss the inferred outer atmospheric flow and turbulent velocities,
the relative and absolute strength of emission from C 2 and Fe 2,
the ionization fraction of iron, and variations of its spectrum with
time. We also discuss two fluorescence processes operating in the
atmospheres of carbon stars and compare in detail the Mg 2 profiles
seen in both carbon and O-rich stars.

---------------------------------------------------------
Title: Digging Deeper in the Coronal Graveyard
Authors: Ayres, Thomas R.; Brown, Alexander; Harper, G. M.; Bennett,
P. D.; Linsky, J. L.; Carpenter, K. G.; Robinson, R. D.
1997ApJ...491..876A Altcode:
Soft X-ray detections of stellar coronae (T ~ 106 K) are
rare in the giant branch redward of ~K1 III. We have conducted a less
direct--but more sensitive--search using the Hubble Space Telescope
Goddard High-Resolution Spectrograph to probe for far-ultraviolet
proxies of the hot coronal gas in representative “noncoronal”
red giants. In every target so far examined, we find weak but
statistically significant Si IV emission, as well as, commonly,
C IV and, in some cases, N V. Si IV is not affected by the CNO
anomalies produced by the first dredge-up, which can deplete the
carbon abundance and weaken C IV. In the low-activity giants,
the λ1393 component of the Si IV doublet must be corrected
for sharp absorptions, which we believe are caused by carbon
monoxide in overlying cool material. The normalized flux ratios
(\Rscr≡f/fbol) of Si IV and X-rays among the “coronal”
yellow giants (lying just blueward of the “noncoronal” zone) fall on a
uniform track, \RscrX~\Rscr2SiIV. In
the noncoronal zone, however, the Si IV index is nearly constant
(\RscrSiIV~10-8), independent of \RscrX
(which ranges from ~10-8 to &lt;~10-10). The
mechanism that diminishes X-ray activity in the red giants is highly
sensitive to an as yet unidentified stellar property. Photoelectric
absorption by cool gas might play a more important role than previously
suspected, particularly if hot magnetic loops are partly or completely
buried in the chromosphere.

---------------------------------------------------------
Title: Pondering Puzzling Profiles: MG II Emission from Carbon Stars
Authors: Carpenter, K. G.; Robinson, R. D.; Johnson, H. R.
1997AAS...191.1306C Altcode: 1997BAAS...29.1230C
We have obtained spectroscopic observations of the Mg II h &amp; k
emission lines from three carbon stars, using the moderate resolution
(R&gt;=20,000) G270M grating of the Goddard High Resolution Spectrograph
(GHRS) on the Hubble Space Telescope (HST). The emission profiles
from all three stars are very broad and heavily mutilated by overlying
absorption. The profiles from two of the stars, TX Psc (N0; C6,2) and
TW Hor (N0; C7,2), are very similar. However, the profiles from the
third star, UU Aur (N3; C5,3) are dramatically different from the other
two stars on the blue side, with strong emission persisting out to ~
-200 km/s (cf. to only weak emission out to ~ -100 km/s in TX Psc and
TW Hor). If the intrinsic (i.e. chromospheric) width of the emission in
the carbon stars is comparable to that in oxygen-rich giants, then the
spectra of the first two carbon stars are easily understood in terms of
additional overlying absorptions, but the amount of excess emission from
the blue side of the UU Aur profiles is difficult to explain. If, on
the other hand, the intrinsic width of the Mg II emission in the carbon
stars is more comparable to that of the supergiant oxygen-rich stars
(e.g. alpha Ori), then all the carbon stars have tremendous overlying
absorption on both the blue and red wings of the profiles and UU Aur
is notable only because it has significantly less absorption on the
blue-side of the profiles, relative to the other carbon stars. In this
paper, we present an analysis of the spectra and our interpretation,
based on all the available data, of these fascinating and complex line
profiles and their formation.

---------------------------------------------------------
Title: Hubble Space Telescope Spectroscopy of the Carbon Star
TX Piscium
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Johnson, Hollis
R.; Eriksson, Kjell; Gustafsson, Bengt; Pijpers, Frank P.; Querci,
Francois; Querci, Monique
1997ApJ...486..457C Altcode:
Ultraviolet spectra obtained with the Hubble Space Telescope of the
carbon star TX Piscium (HR 9004) are presented, along with analysis
providing information on its outer atmosphere, including flow and
turbulent velocities, line formation mechanisms, and variations with
time. Both thermal (collisionally excited) and fluorescent emission
from the chromosphere of the star appear to be formed near the stellar
rest velocity, i.e., in a region below that in which the stellar wind is
accelerated. Absorption self-reversals in the Mg II emission confirm the
presence of an outflowing stellar wind at a mean velocity of about 9-10
km s-1. Circumstellar absorption features (Mn I and Fe I)
overlying the Mg II emission indicate a cool shell expanding at about
5-6 km s-1 relative to the photosphere. The widths (FWHM)
of various emission lines indicate that the chromospheric turbulence is
at least 16 km s-1, but that it may increase with altitude
to as much as 34 km s-1. Three hours of integration on
the C II] lines are examined for any signs of variability that might
indicate the presence of shocks, but no statistically significant
variations are seen. A previous identification (in spectra of UU Aur)
of an emission line at 2807 Å, seen only in spectra of carbon stars,
as belonging to Fe I multiplet UV45 pumped by the C II] line at 2325 Å
is confirmed by the discovery of an absorption feature corresponding
exactly to the wavelength of the pumped transition (Fe I UV13) near
2325 Å. Lines from Fe II UV165, previously seen in solar off-limb
spectra and in Goddard High-Resolution Spectrograph spectra of α Tau,
are clearly present. The normally much stronger Fe II UV32, 62, and
63 multiplets are seen but are weaker relative to both the UV165 lines
and the intercombination lines of C II] and Si II] than in α Tau. The
weakness of these Fe II lines is indicated both by their absolute flux
levels and by their narrow, single-peaked profiles, which are in sharp
contrast to the broad, double-peaked profiles seen in oxygen-rich cool
giant and supergiant stars. The weakness of the Fe II lines and the
presence of the Fe I 2807 Å line suggest that the ionization fraction
of iron (Fe II/Fe I) is significantly lower in the outer atmospheres of
carbon stars. Fluxes in emission lines of Fe II and Mg II are &gt;=2-3
times lower than in a 1984 IUE spectrum of TX Psc, confirming that
the latter was obtained at an epoch of unusual UV brightness for the
star. The Mg II profiles are heavily mutilated by overlying absorption,
even more so than in 1984. The TX Psc profiles are very similar to
those seen in the carbon star TW Hor but are dramatically different
than those in another carbon star, UU Aur, whose lines show violet
wing emission out to much shorter wavelengths than in the other two
stars. 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 and on
observations at the Haute-Provence Observatory.

---------------------------------------------------------
Title: The dynamical mass of the beat cepheid Y carinae and stellar
opacities.
Authors: Bohm-Vitense, E.; Evans, N. R.; Carpenter, K.; Morgan, S.;
Beck-Winchatz, B.; Robinson, R.
1997AJ....114.1176B Altcode:
The beat Cepheid, Y Carinae A, has a B9 V companion, Y Car
B. The primary period P0 of the Cepheid is 3.64 days
and the secondary, P1, is 2.56 days. Its period ratio
P1/P0 is thus 0.703. Y Car is the only beat
Cepheid known to be a binary and thus offers us the unique opportunity
to determine the dynamical mass for a beat Cepheid. We have determined
its mass by measuring the orbital velocity amplitude of the hot
companion Y Car B using the Goddard High-Resolution Spectrograph (GHRS)
with the G200M grating on the Hubble Space Telescope. When combined
with the ground-based orbital velocity amplitude of the Cepheid
and the mass of the companion, the implied mass of the Cephieid
is M=3.8±1.2Msun. With the Cepheid luminosity given
by the period-luminosity relation, this mass, taken at face value,
indicates excess mixing in the main sequence progenitor corresponding
to convective overshoot by about 0.9 pressure scale height, however,
the large error bars prevent a firm conclusion. As shown by Simon the
period ratio for beat Cepheids depends sensitively on the opacities. For
models calculated with Cox-Tabor opacities the period ratios for beat
Cepheids indicate masses between one and two Msun. Models
calculated with the new Livermore OPAL opacities on the other hand
indicate masses around 4 solar masses. The good agreement of the beat
mass with the dynamical mass, determined here for Y Car, provides a
confirmation that the OPAL opacities are a significant improvement
over the Cox-Tabor (1976) opacities.

---------------------------------------------------------
Title: Observations of 3C273 with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope. II.
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Snow, M.; Randall,
C. E.; Tripp, T. M.; Ake, T. B.; Crenshaw, D. M.; Bruhweiler, F. C.
1997AJ....114..554B Altcode:
Observations of the quasar 3C 273 taken with the Goddard High Resolution
Spectrograph in November and December 1993 are presented here. We have
included both the fully-reduced spectra, and spectra combined with
our earlier (1991) observations. There are a total of 10 new medium
resolution exposures covering four wavelength regions: 1164-1201
Angstroms, 1214-1251 Angstroms, 1537-1573 Angstroms, and 1633-1670
Angstroms. We confirm the suggestion of Morris et al. (1991) that the
galactic Si IV lambda 1393 line is blended with an extragalactic lya
line by observing the lyb counterpart to this extragalactic line. We
obtain an improved upper limit on the C IV/H I ratio in these weak
low redshift lya absorption systems by coadding the corresponding C IV
spectral regions. Improved line profiles for the galactic C IV and N V
absorption are also presented and discussed. The improved measurements
lead to a downward revision of the galactic C IV column density, log N
(C IV) = 14.46+/- 0.04.

---------------------------------------------------------
Title: The Outer Atmospheres of Cool, Low Gravity Stars as Revealed
by HST
Authors: Carpenter, Kenneth G.
1997BaltA...6...73C Altcode: 1997OAst....6...73C
We have used the Goddard High Resolution Spectrograph (GHRS) on
the Hubble Space Telescope (HST) to measure the macroturbulent and
flow velocities, the acceleration of winds, and the amount of hot
(transition-region) plasma in the outer atmospheres of Carbon and K - M
Giant/Supergiant stars. We see the acceleration of the stellar winds in
the chromospheres of several of these stars from initial velocities of 3
- 9 km/s to upper velocities of 15 - 25 km/s and measured chromospheric
macroturbulences ranging from approximately 25 to 35 km/s. We have
found in the non-coronal giant alfa Tau weak C IV emission indicative
of hot transition-region plasma, many new fluorescent lines of Fe II,
and fluorescent molecular hydrogen emission and Ca II recombination
lines seen for the first time in a giant star.

---------------------------------------------------------
Title: The Mass of the Classical Cepheid V350 SGR
Authors: Evans, N. R.; Bohm-Vitense, E.; Carpenter, K.; Beck-Winchatz,
B.; Robinson, R.
1997PASP..109..789E Altcode:
Two medium resolution spectra of the hot companion of the Cepheid V350
Sgr have been obtained with the Goddard High Resolution Spectrograph
aboard the Hubble Space Telescope. Comparison of these spectra (in the
wavelength range 1840 to 1880 \AA) with the spectrum of $\alpha$ Lyr
shows that V350 Sgr B has a projected rotation velocity which may be as
high as 150 km sec$^{-1}$. The velocity difference between the spectra
of V350 Sgr B at two orbital phases is measured to be -23.1 $\pm$ 3.8
km sec$^{-1}$. The error is dominated by the aperture centering. When
combined with the orbital velocity variation of the Cepheid derived
from the ground-based orbit and the mass of the companion deduced
from IUE spectra, the mass of the Cepheid is found to be 5.2 $\pm$
0.9 M$\sun$. The observed mass--luminosity combination of V350 Sgr A
is a good match to recent evolutionary calculations which use moderate
convective overshoot near the main sequence, however, the blue loops
do not extend to temperatures as hot as the Cepheid. (SECTION: Stars)

---------------------------------------------------------
Title: GHRS Observations of Cool Low-Gravity Stars. III. Plasma
Flows and Turbulence in the Outer Atmosphere of α Orionis (M2 Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.
1997ApJ...479..970C Altcode:
We present the results of a Goddard High Resolution Spectrograph (GHRS)
study of flow and turbulent velocities in the outer atmosphere of the
M2 Iab supergiant α Ori. Ions with observed chromospheric emission
features include C I, C II, Si I, Si II, O I, Co II, Al II, Mg II,
Cr II, Fe I, and Fe II, while the photospheric absorption spectrum
is dominated by Fe I. The widths of optically thin lines of C II],
Si II], Co II, and Fe II indicate an average chromospheric turbulent
velocity (Doppler FWHM) in the range of 31-35 km s-1, which
is substantially above the expected chromospheric sound velocity. The
shape of the C II] profiles indicates that this turbulence is probably
anisotropically distributed, with velocities preferentially directed
along and/or perpendicular to the radial direction. The radial
velocity of near-UV Fe I photospheric absorption lines averaged 18
km s-1, somewhat smaller than the systemic RV of α Ori
itself (21 km s-1) and significantly smaller than the RV
of the optical Fe I lines (23 km s-1) at the time of the
HST observations. The various components of the chromospheric emission
lines had radial velocities in the range 7-36 km s-1. The
emission wings for most of the ionic species averaged ~20 km
s-1, i.e., they were nominally at rest with regard to
the star. The central absorption features in these lines, however,
showed lower velocities, averaging ~16 km s-1. The radial
velocity of the central reversals in the stronger lines was also found
to be correlated with the opacity of the lines, changing from ~20 km
s-1 for the lower opacity lines to ~14 km s-1
for the higher opacity lines. This implies that we are directly viewing
the acceleration of the stellar wind in the chromosphere from rest to
about 7 km s-1. Contrary to the results reported earlier
by Carpenter (1984) on the basis of IUE data, there is no indication
of a deceleration of the wind at large distances from the star.

---------------------------------------------------------
Title: The Mass of the Classical Cepheid S Muscae
Authors: Böhm-Vitense, Erika; Remage Evans, Nancy; Carpenter, Kenneth;
Beck-Winchatz, Bernhard; Robinson, Richard
1997ApJ...477..916B Altcode:
A good determination of the mass-luminosity relation for evolved stars
on blue loops can determine the degree of excess mixing in the interiors
of their main-sequence companions. In this study we determine the
dynamical mass of the Cepheid binary S Muscae. This can be combined
with its known luminosity and be fitted on evolutionary tracks to
determine the amount of mixing in the main-sequence progenitor. Using the Goddard High Resolution Spectrograph on the Hubble Space
Telescope we have measured the orbital radial velocity changes for the
companion of the Cepheid S Mus. Spectra taken at minimum and maximum
orbital velocities were cross-correlated. The velocity difference was
measured to be 30.6 +/- 0.4 km s-1. The difference for the
orbital velocities of the Cepheid for the same phases was determined
to be 26.9 km s-1 +/- 0.4 km s-1. This gives
a velocity ratio of 1.14 +/- 0.02, which gives us the mass ratio for
the companions. Adding possible centering errors of the target in the
entrance apertures the error limit would be increased to +/-0.06. The derived spectral types of the companion S Mus B range from B3
V to B5 V depending on the criterion used to determine it, with an
average spectral type B3.8 V. Using the average spectral type and the
main-sequence mass-spectral type relation from Andersen &amp; Harmanec
we find for S Mus B a mass of 5.2 +/- 0.2 M⊙. With the
newly determined mass ratio the mass for the Cepheid S Mus A comes out
to be 5.9+0.7-0.6 M⊙. Taking
the mass of 5.9 M⊙ at face value and adopting the absolute
visual magnitude of Mv = -4.29 (log L/L⊙ =
3.62) for the Cepheid S Mus this indicates mixing in its main-sequence
progenitor slightly in excess of the one assumed for the Maeder and
Meynet evolutionary tracks. The present uncertainties in mass and
luminosity prevent, however, a firm conclusion about the exact degree
of mixing. Based on observations made with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA Contract No. NASS-26555.

---------------------------------------------------------
Title: Winds and Mass-Loss from Evolved, Low-Gravity Cool Stars
Authors: Carpenter, K.; Robinson, R.
1997IAUJD...8E..28C Altcode:
The character of the winds and the amount of mass-loss from stars
during the red giant and supergiant stage of evolution are critical
to the progression of that evolution. We therefore summarize here the
results of a series of programs utilizing the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST) to study the
winds and mass-loss from the surface of evolved, low-gravity cool
stars. We discuss the structure of the chromospheres in which the
base of these stellar winds lie, the velocity of the wind and its
acceleration with height, and what these spectra tell us about the
mass-loss from these stars. Because of its relevance to this Joint
Discussion, we will also discuss in some detail what we have learned
about real-time variability of these phenomena and the implied somewhat
erratic nature of the mass-loss process in at least some of these stars.

---------------------------------------------------------
Title: Fishing in the Coronal Graveyard
Authors: Ayres, T. R.; Brown, A.; Harper, G. M.; Bennett, P. D.;
Linsky, J. L.; Carpenter, K. G.; Robinson, R. D.
1996AAS...189.7815A Altcode: 1996BAAS...28.1379A
Hot coronae (T ~ 10(6) K) are thought to be rare among single giant
stars to the right of the “Linsky--Haisch dividing line” near K0 in
the H--R diagram. K and M giants are such slow rotators that absence of
dynamo generated magnetic activity would be natural. Nevertheless,
gamma Dra (K5 III) unexpectedly was detected in FUV coronal
proxies---hot lines Si IV lambda 1393 and C IV lambda 1548---by HST
/GHRS during Science Verification, and subsequently was discovered
as a faint X-ray source in a deep ROSAT /PSPC pointing. Is gamma Dra
anomalous, or is the lack of coronal detections among the K giants
simply a matter of insufficient sensitivity? We have used the GHRS
low resolution mode to search for additional examples of hot lines
among inactive single red giants. Si IV provides a clean diagnostic
of subcoronal material because it falls near the peak sensitivity
of the G140L mode and does not suffer from abundance depletions that
can affect C IV in red giants. X-ray/Si IV ratios are such that HST
can reach to much fainter limiting “coronal” magnitudes than even
very deep ROSAT pointings. In every target so far examined, we find
weak---but statistically significant---Si IV emission. These include:
the ancient red giant Arcturus (alpha Boo: K1 III), recorded at the
end of Cycle 5; and epsilon Crv (K2.5 III) and epsilon Sco (K2 III)
observed in Cycle 6. X-ray/Si IV ratios of red giants (for which
measurements, or upper limits, of both diagnostics are available)
fall on a uniform track, extending downward from active K0 “Clump”
giants like beta Ceti all the way to Arcturus itself, in the depths of
the “coronal graveyard.” The systematic behavior argues that magnetic
dynamo action continues even when long term angular momentum loss has
slowed the stellar spin to a crawl. This work was supported by grant
GO-06066.01-94A from STScI.

---------------------------------------------------------
Title: New Results on Cepheid Masses
Authors: Evans, N. R.; Bohm-Vitense, E.; Carpenter, K.; Robinson,
R.; Beck-Winchatz, B.
1996AAS...189.9608E Altcode: 1996BAAS...28.1399E
Masses for Cepheid variable stars can be measured by combining the
orbital velocity amplitude for the Cepheid (from a ground-based orbit)
with the orbital velocity amplitude of a hot main sequence companion
(observed in the ultraviolet from satellites such as IUE and HST) and
the mass of the companion (inferred from from the ultraviolet energy
distribution). Observations of 5 binary systems are now completed
or in progress with the Goddard High Resolution Spectrograph on the
Hubble Space Telescope. Recently completed observations of U Aql lead
to a mass of 5.1 +/- 1.1 Msun . We will discuss the results for S Mus,
V350 Sgr, U Aql, and Y Car, and the constraints they place on stellar
evolution calculations. As would be expected, some of the B companions
have high rotational velocities, decreasing the accuracy with which
their orbital velocities can be measured. The preliminary conclusion
from the 4 HST targets and SU Cyg (mass from IUE observations) is that
a weighted mean indicates no convective overshoot but the mode (which
reflects the HST results better) agrees with the modest overshoot
used in the Geneva evolutionary calculations. Financial Support was
provided by a NASA grant GO-4541-01 to EB--V and GO-4541.02 to KGC,
a grant from the Natural Sciences and Engineering Council, Canada to
NRE, from the AXAF Science Center NASA Contract NAS8-39073.

---------------------------------------------------------
Title: Observing Stellar Coronae with the Goddard High Resolution
Spectrograph. II. The RS CVn Binary System HR 1099
Authors: Robinson, R. D.; Airapetian, V. S.; Maran, S. P.; Carpenter,
K. G.
1996ApJ...469..872R Altcode:
We report time series observations of the RS CVn star HR 1099 taken
with the Goddard High Resolution Spectrograph onboard the Hubble Space
Telescope. The data cover a wavelength range from 1342 to 1375 Å and
show a measurable continuum, as well as emission lines of O I, C I,
CII, Fe II, O V, and Fe XXI. The chromospheric and transition region
features are seen only in the active K1 IV component of the binary
system, while the Fe XXI (1O7 K) flux may come from both
components, with the active component having the stronger flux. There is
no indication of Fe MI emission, formed at 1.3 x 106 K. The
width of the Fe XXI profile indicates that the corona of the primary
is unlikely to extend to heights greater than 2.3R⋆,
while other indicators suggest that the average loops are really
much smaller, having a length of ∼3 x 1010 cm with an
electron density on the order of 1010 cm-3. Some
evidence for atmospheric turbulence is detected in all of the observed
emission lines. This turbulence initially increases with height, going
from less than 30 km s-1 in the chromosphere to as much
as 150 km s-1 in the transition region. The turbulence
then decreases in the corona, where velocities of less than 65 km
s-1 are indicated. Theoretical fits to the O V profile
also suggest that this turbulence is anisotropically distributed,
with motions directed primarily along or perpendicular to the radial
direction. While admitting the possibility that the atmosphere is
heated by microflare events, we examine an alternative heating process
that involves the damping of MHD turbulence, which might be generated
by nonlinear Alfvén waves or by shocks. Simple calculations indicate
that the observed turbulence is sufficient to account for the transition
region and coronal heating.

---------------------------------------------------------
Title: UV Emission from the Atmosphere of Jupiter After the S-Impact
of Comet SL9
Authors: Carpenter, K. G.; McGrath, M. A.; Yelle, R. V.
1996DPS....28.2247C Altcode: 1996BAAS...28.1150C
The Hubble Space Telescope Faint Object Spectrograph was used to
obtain a UV spectrum of the impact site of the S-fragment of comet
SL9 approximately 45 minutes after the entry of the fragment into the
atmosphere of Jupiter. This spectrum contains ultraviolet emission
lines of neutral and ionized metals, including Mg I, Mg II, Fe I,
Fe II, and Si I. Initial analyses of these data were presented by
Noll et al. (1995, Science, 267, 1307) based on a pure solar resonance
fluoresence synthetic spectrum and assuming collisional excitation at
1000 K, and by Carpenter et al. (DPS, Oct. 1995) who added non-resonance
fluorescence and examined the possibility that some of the emission was
caused by thermal excitation of metastable levels during the fireball
and splashback phases of the impact. Since these line formation models
do not fully account for the observed relative and absolute line fluxes,
we have enhanced our model to include non-LTE effects, heating of the
atmosphere due to infalling gas and dust, and the effects of multiple
scatterings of photons as they attempt to exit the atmosphere of
Jupiter at frequencies within optically thick lines. We compare the
synthetic spectrum produced with this model to the observed spectrum
and discuss the physical conditions and elemental abundances inferred
from this comparison.

---------------------------------------------------------
Title: High Signal-to-Noise Ratio Observations of Weak Interstellar
Absorption Lines Towards XI Ophiuchi With the Goddard High-Resolution
Spectrograph Aboard the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Hogen, R.; Snow, M.;
Cardelli, J. A.; Ake, T. B.; Bruhweiler, F.
1996AJ....112.1128B Altcode:
We present an atlas and tabulation of weak interstellar absorption lines
in the ultraviolet spectrum of ζ Ophiuchi in four selected wavelength
regions observed with the Goddard High Resolution Spectrograph aboard
the Hubble Space Telescope. The signal-to-noise ratio ranges from 150 to
nearly 400, and the spectral resolving power exceeds 20 000, allowing
2σ detections of features as weak as Wλ=0.8 mÅ. We report positive
measurements of two lines of OH, and weak detections of P I, Tl II,
and N V. Upper limits of Wλ&lt;1 mÅ are found for the molecules
H2O, HCl, SiO, NO+, and CH2. Similar limits
are found for heavy elements Te II, Co II, and Sb II. Three lines are
present in our spectrum for which we have no identifications. They are
found at wavelengths of λ=1229.84, 1313.98, and 1314.23 Å. However,
none of the features reported by previous authors as unidentified
absorption lines in the wavelength regions we have observed are present
in our data.

---------------------------------------------------------
Title: Hubble Space Telescope Observations of the Seyfert Galaxy
NGC 3783: Discovery of Variable C IV Absorption
Authors: Maran, Stephen P.; Crenshaw, D. Michael; Mushotzky, Richard
F.; Reichert, Gail A.; Carpenter, Kenneth G.; Smith, Andrew M.;
Hutchings, John B.; Weymann, Ray J.
1996ApJ...465..733M Altcode:
We have discovered variable absorption lines in HST spectra of the
Seyfert 1 galaxy NGC 3783. C IV λλ1548.2, 1550.8 absorption is present
in an FOS spectrum on 1992 July 27 and a GHRS spectrum on 1994 January
16 at a radial velocity of -450 km s^-1^ relative to the emission-line
peak, but there is no evidence for absorption in a GHRS spectrum on 1993
February 5. A GHRS spectrum on 1993 February 21, obtained just 16 days
after the spectrum with no detectable C IV absorption, shows strong
N V λλ1238.8, 1242.8 absorption lines, also at a radial velocity of
-450 km s^-1^. The observations place constraints on the two types of
models for absorption-line variability: bulk motion into the line of
sight, and variable ionization of gas already in the line of sight.

---------------------------------------------------------
Title: Probing the Chromospheric Structure of Alpha Tau
Authors: Carpenter, Kenneth
1996hst..prop.6722C Altcode: 1996hst..prop.3133C
Fluorescent H_2 lines {excited by Hydrogen LyAlpha} and Ca II lines
formed by recombination after photoionization by H LyAlpha were recently
seen in GHRS spectra of the K5 III star Alpha Tau. This is the first
time these lines have been seen in a giant star. The presence of these
lines provides an opportunity to probe the structure of the upper
chromosphere {Ca II} and of the low chromosphere/temperature minimum
region {H_2} in this star and to test existing and new theoretical
models of the outer atmosphere of Alpha Tau. In addition, the H_2 lines
allow us to probe cooler regions than possible using the standard atomic
emission line diagnostics and thus enable us to test the hypothesis of
Wiedemann et al. {1994 ApJ 423, 806} that the atmosphere of cool giants
are thermally bifurcated in the region above the photosphere. We propose
to obtain, during Cycle 6, observations of the full set of Ca II and
H_2 lines needed to perform these analysis and tests and to use these
data to create new models of the chromosphere of Alpha Tau.

---------------------------------------------------------
Title: HST Studies of Carbon and K-M Giant/Supergiant Stars
Authors: Carpenter, K. G.; Robinson, R. D.
1996swhs.conf..418C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Empirical constraints on wind flows and turbulence from HST
observations of cool giants and supergiants
Authors: Carpenter, K. G.
1996ASPC..109..243C Altcode: 1996csss....9..243C
No abstract at ADS

---------------------------------------------------------
Title: Rapid UV spectroscopy of flares on YZ CMi
Authors: Robinson, R. D.; Woodgate, B. E.; Carpenter, K. G.
1996ASPC..109..285R Altcode: 1996csss....9..285R
No abstract at ADS

---------------------------------------------------------
Title: Identification and analysis of UV emission lines observed near
1550 Angstroms in the spectrum of alpha Tau obtained with the GHRS
Authors: McMurry, A. D.; Jordan, C.; Rowe, A. K.; Carpenter, K. G.;
Robinson, R. D.
1996ASPC..109..271M Altcode: 1996csss....9..271M
No abstract at ADS

---------------------------------------------------------
Title: Examining the coronal heating on the RS CVn binary HR 1099
Authors: Airapetian, V.; Robinson, R. D.; Maran, S. P.; Carpenter,
K. G.
1996ASPC..109..249A Altcode: 1996csss....9..249A
No abstract at ADS

---------------------------------------------------------
Title: The Transition Region, Corona, Chromosphere, and Wind of the
K5 Giant gamma Draconis
Authors: Brown, A.; Carpenter, K. G.; Robinson, R. D.; Harper, G. M.;
Deeney, B. D.; Ayres, T. R.
1995AAS...18710303B Altcode: 1995BAAS...27.1430B
Gamma Draconis (K5 III) is the first single, normal late K giant
located on the red side of the coronal “dividing line” known to
show conclusive evidence for both hot ( ~ 10(5) K) transition \
region (TR) and coronal (&gt; 10(6) K) plasma. We present HST GHRS
ultraviolet spectra of gamma Dra obtained on 1995 July 20 and 1991
April 6/18. These observations include spectra obtained at low, medium,
and echelle resolution that provide a full set of chromospheric and
TR emission line fluxes and profiles. These are combined with ROSAT
PSPC observations to measure the TR and coronal properties, such
as emission measure distribution, electron density, and nonthermal
velocity fields, of this star. The high temperature emissions of gamma
Dra are compared to those of a sample of hybrid-chromosphere bright
giants and supergiants. This work is supported by Space Telescope
Science Institute grant GO-06068.01-94A and NASA grants NAG5-1792 and
NAGW-4529 to the University of Colorado.

---------------------------------------------------------
Title: The Mass of the Cepheid S Muscae.
Authors: Bohm-Vitense, E.; Evans, N. R.; Beck-Winchatz, B.; Carpenter,
K.; Robinson, R.
1995AAS...18710205B Altcode: 1995BAAS...27.1428B
Using the Goddard High Resolution Spectrograph on the Hubble Space
Telescope we have measured the orbital radial velocity changes for
the companion of the Cepheid S Muscae. The observations were done
at minimum and maximum orbital velocities. The two spectra were
cross-correlated. The velocity difference was measured to be 30.6 +/-
0.4 km/s. The difference for the orbital velocities of the Cepheid
for the same phases was determined to be 26.9 +/-0.4 km/s. This gives
a mass ratio of 1.14 +/-0.06. For a spectral type between B3.5 V and
B5 V for the companion S Mus B its mass is 5.0 +/- 0.3 M(sun). With
the mass ratio of 1.14 the mass of the Cepheid, with a period of 9.6
days, comes out to be 5.7 +/- 0.4 solar masses. This compares with a
pulsational mass of 5.5 solar masses. Taking the 5.7 solar masses for
the Cepheid at face value its absolute visual magnitude of M(V)=-4.29
indicates a high degree of excess interior mixing in its main sequence
progenitor corresponding to convective overshoot by one pressure
scale height. Even for the upper mass limit the excess mixing has to
correspond to convective overshoot by 1/2 pressure scale height.

---------------------------------------------------------
Title: The Astrophysical Laboratory RR Tel: Observations
Authors: Harper, G. M.; Brown, A.; Robinson, R. D.; Jordan, C.;
Carpenter, K. G.; Shore, S. N.
1995AAS...187.1910H Altcode: 1995BAAS...27.1313H
The rich emission line spectrum of the bright symbiotic nova RR
Tel provides one of the best laboratories for determining empirical
values of atomic parameters, including branching ratios, Einstein
A-values and electron collision strengths. In addition to providing
atomic parameters not measurable in the laboratory, the observations
also test recent theoretical calculations of these parameters. In July
1995 we obtained high quality low and medium resolution, large aperture
spectra of RR Tel using the Goddard High Resolution Spectrograph (GHRS)
on board the Hubble Space Telescope. These spectra sample wavelengths
from 1100 Angstroms to 2680 Angstroms and contain numerous lines of
astrophysical interest which will be used to derive empirical atomic
data (e.g. branching ratios in C II], N III], O III] and O IV])
as well as lines from which the local temperature and density can
be determined. The GHRS spectra have greater dynamic range and lower
background noise than available high resolution IUE data, permitting
detailed evaluation of spectral diagnostics even for the weak emission
features from some intercombination and forbidden transitions. In this
paper we show examples of the spectra, discuss the atomic transitions
for which atomic data will be derived and describe the methods used in
determining these parameters. RR Tel and AG Peg, both of which have been
observed with the GHRS, are fundamental for studying time variability
of spectra of a symbiotic nova and the GHRS observations will be
compared with previous IUE results to investigate this variability. We
will also discuss the observed flows and turbulence found from the
line profiles as well as the shape of the UV continuum. Support for
this work was provided by NASA through grant number GO-05863.01-94A
from the Space Telescope Science Institute, which is operated by the
Association of Universities for research in Astronomy, Inc., under
NASA contract NAS5-26555.

---------------------------------------------------------
Title: A Search for Microflaring Activity on dMe Flare
Stars. I. Observations of the dM8e Star CN Leonis
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.;
Bookbinder, J. A.
1995ApJ...451..795R Altcode:
Microflares are frequent, short-duration, energetically weak
disturbances occurring in the nonradiatively heated regions of the
Sun and other magnetically active stars. They are thought to be the
low-energy extension of flares commonly seen on active dMe stars and
may be a major source of heating the chromosphere and corona of cool
stars in general. In this paper we describe rapid time sequence UV
photometry of the dMe star CN Leo taken with the High Speed Photometer
(HSP) aboard the Hubble Space Telescope (HST). The filter was centered
at 240 nm, near wavelengths at which flares are expected to have
maximum intensity and the stellar background is small. During 2 hr of
on-source observing, a total of 32 flarelike events were detected,
with integrated counts ranging from 12 to more than 14,000. In most
cases the events had integrated energy ranging between 1027
and 1028 ergs and can be classified as microflares. A
considerable fine structure was seen in these events, with substantial
variations sometimes occurring on timescales of less than 1 s. The
occurrence rates for the smaller events showed a power-law distribution,
with a slope comparable to that seen for larger events observed from
the ground. Extrapolating the occurrence rate relation to nanoflare
energies indicates a predicted count rate that is significantly smaller
than that observed, suggesting that the nanoflares have a different
energy distribution than the larger events.

---------------------------------------------------------
Title: The Goddard High Resolution Spectrograph: In-Orbit Performance
Authors: Heap, S. R.; Brandt, J. C.; Randall, C. E.; Carpenter, K. G.;
Leckrone, D. S.; Maran, S. P.; Smith, A. M.; Beaver, E. A.; Boggess,
A.; Ebbets, D. C.; Garner, H. W.; Hutchings, J. B.; Jura, M.; Linsky,
J. L.; Savage, B. D.; Cardelli, J. A.; Trafton, L. M.; Walter, F. M.;
Weymann, R. J.; Ake, T. B.; Crenshaw, D. M.; Malumuth, E. M.; Robinson,
R. D.; Sandoval, J. L.; Shore, S. N.; Wahlgren, G. M.; Bruhweiler,
F.; Lindler, D. J.; Gilliland, R. L.; Hulbert, S. J.; Soderblom, D. R.
1995PASP..107..871H Altcode:
The in-orbit performance of the Goddard High Resolution Spectrograph
onboard the Hubble Space Telescope (HST) is presented. This report
covers the pre-COSTAR period, when instrument performance was
limited by the effects of spherical aberration of the telescope's
primary mirror. The digicon detectors provide a linear response
to count rates spanning over six orders of magnitude, ranging from
the normal background flux of 0.01 counts diode ^-1 s^-1 to values
larger than 10^4 counts diode^-1 s^-1. Scattered light from the
first-order gratings is small and can be removed by standard background
subtraction techniques. Scattered light in the echelle mode is more
complex in origin, but it also can be accurately removed. Data
have been obtained over a wavelength range from below 1100 A to
3300 A, at spectral resolutions as high as R = lambda/delta-lambda =
90,000. The wavelength scale is influenced by spectrograph temperature,
outgassing of the optical bench, and interaction of the magnetic field
within the detector with the earth's magnetic field. Models of these
effects lead to a default wavelength scale with an accuracy better
than 1 diode, corresponding to 3 km s^-1 in the echelle mode. With
care, the wavelength scale can be determined to an accuracy of 0.2
diodes. Calibration of the instrument sensitivity functions is tied into
the HST flux calibration through observations of spectrophotometric
standard stars. The measurements of vignetting and the echelle
blaze function provide relative photometric precision to about 5% or
better. The effects of fixed-pattern noise have been investigated,
and techniques have been devised for recognizing and removing it
from the data. The ultimate signal-to-noise ratio achievable with the
spectrograph is essentially limited only by counting statistics, and
values approaching 1000:1 have been obtained. (SECTION: Astronomical
Instrumentation)

---------------------------------------------------------
Title: Formation of Atomic Emission Lines in the Atmosphere of
Jupiter After the Comet Shoemaker-Levy 9 S Impact
Authors: Carpenter, K. G.; McGrath, M. A.; Yelle, R. V.; Noll, K. S.;
Weaver, H. A.
1995DPS....27.2203C Altcode: 1995BAAS...27Q1118C
No abstract at ADS

---------------------------------------------------------
Title: An Atlas of Alpha Orionis Obtained with the Goddard High
Resolution Spectrograph on the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess,
A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.;
Leckrone, D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith,
A. M.; Trafton, L. M.; Walter, F. M.; Weymann, R.; Snow, M.; Randall,
C. E.; Ake, T. B.; Robinson, R. D.; Wahlgren, G.
1995AJ....109.2706B Altcode:
An atlas of observations of the late-type supergiant a Orionis taken
with the Goddard High Resolution Spectrograph in 1992 September is
presented. We have included identifications of the major features along
with the fully reduced spectrum. The 33 exposures consist of 3 high
resolution (R∼80,000) and 30 medium resolution (R ∼20,000∼35,000)
observations. The latter provide complete wavelength coverage from
1980 to 3300 Å.

---------------------------------------------------------
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: Outer Layers of a Carbon Star: The View from the Hubble
Space Telescope
Authors: Johnson, Hollis R.; Ensman, Lisa M.; Alexander, David R.;
Avrett, Eugene H.; Brown, Alexander; Carpenter, Kenneth G.; Eriksson,
Kjell; Gustafsson, Bengt; Jorgensen, Uffe G.; Judge, Philip D.; Linsky,
Jeffrey L.; Luttermoser, Donald G.; Querci, Francois; Querci, Monique;
Robinson, Richard D.; Wing, Robert F.
1995ApJ...443..281J Altcode:
To advance our understanding of the relationship between stellar
chromospheres and mass loss, which is a common property of carbon stars
and other asymptotic giant branch stars, we have obtained ultraviolet
spectra of the nearby N-type carbon star UU Aur using the Hubble
Space Telescope (HST). In this paper we describe the HST observations,
identify spectral features in both absorption and emission, and attempt
to infer the velocity field in the chromosphere, upper troposphere,
and circumstellar envelope from spectral line shifts. A mechanism
for producing fluoresced emission to explain a previously unobserved
emission line is proposed. Some related ground-based observations are
also described.

---------------------------------------------------------
Title: MG II H and K Profiles in High-Luminosity, Late-Type Stars
Authors: Robinson, R. D.; Carpenter, K. G.
1995ApJ...442..328R Altcode:
Using high-resolution spectroscopic data taken with the Goddard High
Resolution Spectrographic (GHRS) aboard the Hubble Space Telescope
(HST) and with the International Ultraviolet Explorer (IUE) satellite,
we compare the profiles of the Mg II h and k lines seen in stars with
spectral types ranging from early K through mid-M and luminosities
from giants to supergiants. For all of these stars the lines are
broad emission features with a central absorption. When plotted on a
velocity scale the absorption features of the h and k lines agree very
well in both shape and position, as do the blue wings of the emission
component. The red wings of the emission, however, show a pronounced
difference, with the k line wing consistently shifted to the red of the
h line wing. At present the reason for this discrepancy is unknown,
but we suggest several possibilities, including radiative transfer
effects and high-speed stellar winds.

---------------------------------------------------------
Title: Fe II Line Profiles as Stellar Wind Diagnostics in M Giant
and Supergiant Stars
Authors: Carpenter, K. G.; Robinson, R. D.
1995AAS...186.2220C Altcode: 1995BAAS...27..844C
Detailed study of high resolution, high signal-to-noise chromospheric
Fe II emission line profiles, obtained with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope, provides an opportunity
to probe the flow velocities in the outer atmospheres/winds of cool,
low-gravity stars. We have previously reported seeing the acceleration
of the outflowing wind in such data from several M-giant stars,
including gamma Cru (M3.4 III), mu Gem (M3 IIIab), and alpha Tau (K5
III). Early attempts to do the same with the M-supergiant alpha Ori
(M2 Iab) met with limited success, due to the high-opacity of its outer
atmosphere and the significant differences in the character and behavior
of the observed line profiles in the supergiant spectrum. Further
analysis of the GHRS observations of Fe II lines in alpha Ori has
now enabled us to detect the accelerating outflow in it's wind as
well. A detailed comparison of the observed Fe II profiles and the
flows inferred from those profiles, with those for the less-luminous,
but similar Teff M-giant gamma Cru are presented.

---------------------------------------------------------
Title: Line Identifications in Goddard High Resolution Spectrograph
Observations of Cool, High-Luminosity Stars
Authors: Carpenter, K. G.; Robinson, R. D.
1995ASPC...81..559C Altcode: 1995lahr.conf..559C
No abstract at ADS

---------------------------------------------------------
Title: Observations of Fe XXI on the RS CVn star HR 1099: deducing
the coronal properties
Authors: Robinson, R. D.; Airapetian, V. S.; Maran, S. P.; Carpenter,
K. G.
1995IAUS..176P.191R Altcode:
No abstract at ADS

---------------------------------------------------------
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: GHRS and IUE Observations of the Symbiotic Binary CI Cygni
Authors: Jalakas, M.; Stencel, R. E.; Carpenter, K. G.; Robinson, R. D.
1994AAS...185.2111J Altcode: 1994BAAS...26.1345J
The interacting symbiotic binary star, CI Cygni, is a system
which consists of a hot star orbiting a red giant. Matter from
the larger star is being transfered to the smaller one. Both IUE
and more recently, the Goddard High Resolution Spectrograph on HST
have detected variable ultraviolet emission lines produced by this
transfer. Phase-dependent changes to the doppler velocity of the
matter allow us to map the direction of the flow. Using the HST
snd IUE spectrometers, we re-examined two different types of lines
(resonance and intercombination) which had been reported to show
velocity differences. We will present an analysis of these data showing
the relative locations of high and low density features in the matter
transfer in this system. The lead authors are pleased to acknowledge
partial support for this effort through NASA grant NAG5-2368 to the
University of Denver.

---------------------------------------------------------
Title: Coronal Heating Mechanisms: A Search for Microflare Activity
on YZ CMi
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
1994AAS...185.4506R Altcode: 1994BAAS...26.1380R
We report on time series photometric observations of the dM4.5e flare
star YZ CMi taken in 1993 Nov with the High Speed Photometer aboard
the Hubble Space Telescope. The data consist of five 30 minute time
sequences, with a sampling rate of 0.01s, which were taken through
the F240W filter (centered at 240nm with a 800 Angstroms width). This
setup was selected since the flare energy is expected to be large and
the stellar background is small at these wavelengths. The observations
show a stellar background of 120 counts s(-1) on which are superimposed
well defined flare events ranging in integrated energy from 10(28)
to 10(30) ergs, as well as longer term variations with an amplitude
of up to 50% of the continuum intensity and time scales ranging from
several minutes to hours. These results are compared with data from
the dM8e flare star CN Leo, obtained earlier with the same experimental
setup. CN Leo has a quiescent X-ray flux which is 1/30 that of YZ CMi,
but had a higher occurrence rate of microflares. On the other hand,
the stellar UV background, which must be chromospheric in origin,
is less than 1/25th that seen on YZ CMi. This suggests a link between
chromospheric and coronal heating.

---------------------------------------------------------
Title: The Goddard High Resolution Spectrograph: Instrument, Goals,
and Science Results
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Ake, T. B.; Bruhweiler,
F.; Cardelli, J. A.; Lindler, D. J.; Malumuth, E.; Randall, C. E.;
Robinson, R.; Shore, S. N.; Wahlgren, G.
1994PASP..106..890B Altcode:
The Goddard High Resolution Spectrograph (GHRS), currently in Earth
orbit on the Hubble Space Telescope (HST), operates in the wavelength
range of 1150-3200A with spectral resolutions (lambda/delta-lambda)
of approximately 2 X 10^3, 2 X 10^4, and 1 X 10^5. This paper describes
the instrument and its development from inception, its current status,
the approach to operations, representative results in the major areas
of the scientific goals, and prospects for the future. (SECTION:
Instrumentation and Data Analysis)

---------------------------------------------------------
Title: GHRS Observations of Cool, Low-Gravity Stars. I. The
Far-Ultraviolet Spectrum of alpha Orionis (M2 Iab)
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Wahlgren,
Glenn M.; Linsky, Jeffrey L.; Brown, Alexander
1994ApJ...428..329C Altcode:
We present far-UV (1200-1930 A) observations of the prototypical red
supergiant star alpha Ori, obtained with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST). The
observations, obtained in both low- (G140L) and medium- (G160/200M)
resolution modes, unambiguously confirm that the UV 'continuum'
tentatively seen with (IUE) is in fact a true continuum and is not due
to a blend of numerous faint emission features or scattering inside
the IUE spectrograph. This continuum appears to originate in the
chromospheric of the star at temperatures ranging from 3000-5000 K,
and we argue that it is not related to previously reported putative
companions or to bright spots on the stellar disk. Its stellar origin
is further confirmed by overlying atomic and molecular absorptions from
the chromosphere and circumstellar shell. The dominant structure in
this spectral region is due to nine strong, broad absorption bands of
the fourth-positive A-X system of CO, superposed on this continuum in
the 1300-1600 A region. Modeling of this CO absorption indicates that it
originates in the circumstellar shell in material characterized by T =
500 K, N(CO) = 1.0 x 1018 per sq cm, and Vturb
= 5.0 km per sec. The numerous chromospheric emission features are
attributed mostly to fluorescent lines of Fe II and Cr II (both
pumped by Lyman Alpha) and S I lines, plus a few lines of O I, C I,
and Si II. The O I and C I UV 2 multiplets are very deficient in flux,
compared to both the flux observed in lines originating from common
upper levels but with markedly weaker intrinsic strength (i.e., O I
UV 146 and C I UV 32) and to the UV 2 line fluxes seen in other cool,
less luminous stars. This deficiency appears to be caused by strong
self-absorption of these resonance lines in the circumstellar shell
and/or upper chromosphere of alpha Ori. Atomic absorption features,
primarily due to C I and Fe II are clearly seen in the G160M spectrum
centered near 1655 A. These Fe II features are formed at temperatures
that can occur only in the chromosphere of the star and are clearly
not photospheric or circumstellar in origin.

---------------------------------------------------------
Title: Examining the Corona of HR 1099 with the Hubble Space Telescope
Authors: Robinson, R. D.; Maran, S. P.; Carpenter, K. G.; Brandt,
J. C.; Linsky, J. L.
1994AAS...184.0515R Altcode: 1994BAAS...26Q.865R
A pilot program for the study of stellar coronae through ultraviolet
diagnostic lines is in progress with the Goddard High Resolution
Spectrograph on the Hubble Space Telescope. An initial result of this
program was the detection of the coronal emission line of Fe XXI at 1354
Angstroms in the quiescent spectrum of the dMe star AU Mic (ApJ 421,
800, 1994). The line appeared to be symmetrical, had no measurable
radial velocity with respect to the stellar rest frame, and had a
width which was consistent with a thermal gas of temperature 10(7) K,
suggesting very small turbulence within the formation region. In March
1994, we observed the RS CVn binary HR 1099 = HD 22468 (K1 IV + G5 IV )
using instrumental settings identical to those employed with AU Mic,
but with the added benefit of the recently-installed HST corrective
optics (COSTAR). Each exposure was bracketed by observations of an
on-board wavelength calibration lamp. The results of the series of
eight 27-minute integrations, obtained at one-orbit intervals, will
be presented and compared with the AU Mic spectrum.

---------------------------------------------------------
Title: GHRS Observations of the M-Giant MU GEM
Authors: Carpenter, K. G.; Robinson, R. D.; Johnson, H. R.; Ensman,
L. M.
1994AAS...184.0505C Altcode: 1994BAAS...26..863C
The ultraviolet spectrum of the M-giant mu Gem (M3 IIIab) is sampled
at selected important wavelengths with the Goddard High Resolution
Spectrograph (GHRS) on the Hubble Space Telescope (HST). The wavelength
regions are chosen to include lines sensitive to turbulence and flow
velocities in the stellar chromosphere and wind acceleration region, as
well as some fiducial photospheric absorption features. The dynamics of
the outer atmosphere of mu Gem are examined using the observed profiles
and positions of chromospheric emission lines of C II, Fe II, Mg II, Fe
I, referenced to photospheric absorption lines of Fe I. The content of
the spectra and the inferred flow and turbulent velocities are compared
to those found for the other cool, low-gravity stars observed with GHRS,
including alpha Ori (M2 Iab) and gamma Cru (M3.4 III).

---------------------------------------------------------
Title: Examining the corona of HR 1099 with the Hubble Space
Telescope.
Authors: Robinson, R. D.; Maran, S. P.; Carpenter, K. G.; Brandt,
J. C.; Linsky, J. L.
1994BAAS...26..865R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: HST Observations of the Chromosphere of a Carbon Star
Authors: Ensman, L. M.; Johnson, H. R.; Carpenter, K. G.; Robinson,
R. D.; Luttermoser, D.
1994AAS...184.0506E Altcode: 1994BAAS...26..863E
Ultraviolet spectra from the first Hubble Space Telescope observations
of a carbon star are presented, as well as line identifications and an
initial analysis of the velocity structure of the emitting region. Two
spectra of UU Aur (HD 46687, type N3; C5,3) have been obtained. In the
lower-resolution FOS spectrum (2310 -- 3275 Angstroms), UV emission
lines of Mg I, Mg II, and Fe II, fluoresced lines of Fe I and II,
semi-forbidden emission from C II, Si II, and Al II, absorption lines of
Fe I and Ti II, and absorption by CH and CaCl have been identified. In
the high resolution GHRS spectrum, which covers a 50 Angstroms region
around the Mg II h and k emission lines, overlying Mg II and Mn I
absorption and two fluoresced Fe I lines have been resolved. The Mg
II, and perhaps the Ti II, absorption appears to be interstellar. UV
emission lines of predominantly singly ionized metals indicate the
existence of a chromosphere at ~ 5000 K. In UU Aur, the Mg II emission
clearly arises in material which is flowing away from the star at 35--60
km/s. Shifts of the Fe II emission lines support the conclusion that
the chromosphere is expanding at highly supersonic velocities. However,
overlying Mn I absorption must be due to stationary material further
out. The forbidden and fluoresced lines also come from a region(s)
with negligible velocity. These data imply that shocks may form in the
atmospheres of carbon stars and thus be a mechanism for chromospheric
heating and mass loss. In fact, previous semi-empirical chromospheric
models of the carbon star TX Psc (Luttermoser, Johnson, Avrett, and
Loeser 1989) indicate a similar shock-like velocity field. Luttermoser,
D., Johnson, H. R., Avrett, G., and Loeser, R. 1989, ApJ 345, 543.

---------------------------------------------------------
Title: Ultraviolet and Radio Observations of the Young Rapidly
Rotating k0 Dwarf Star HD197890
Authors: Robinson, R. D.; Carpenter, K. G.; Slee, O. B.; Nelson,
G. J.; Stewart, R. T.
1994MNRAS.267..918R Altcode:
We present the results of UV observations taken with the International
Ultraviolet Explorer (IUE) satellite and microwave observations
obtained with the Australia Telescope during an observing campaign
of the rapidly rotating K0 dwarf star III) 197890, nicknamed `Speedy
Mic'. This star was recently recognized as a powerful, transient EUV
source by the ROSAT WFC, and subsequent investigation showed it to
be a ZAMS or possibly a PMS dwarf which may be a member of the Local
Association. Our observations show it to have strong, variable UV
emission lines near the `saturation' levels. The radio observations
show a level of `quiescent' emission consistent with other rapidly
rotating stars, but there is no evidence for the large flux variations
that normally characterize the time history of such objects.

---------------------------------------------------------
Title: Observing Stellar Coronae with the Goddard High Resolution
Spectrograph. I. The dMe Star AU Microscopii
Authors: Maran, S. P.; Robinson, R. D.; Shore, S. N.; Brosius, J. W.;
Carpenter, K. G.; Woodgate, B. E.; Linsky, J. L.; Brown, A.; Byrne,
P. B.; Kundu, M. R.; White, S.; Brandt, J. C.; Shine, R. A.; Walter,
F. M.
1994ApJ...421..800M Altcode:
We report on an observation of AU Mic taken with the Goddard High
Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The
data consist of a rapid sequence of spectra covering the wavelength
range 1345-1375 A with a spectral resolution of 10,000. The observations
were originally intended to search for spectral variations during
flares. No flares were detected during the 3.5 hr of monitoring. A
method of reducing the noise while combining the individual spectra
in the time series is described which resulted in the elimination of
half of the noise while rejecting only a small fraction of the stellar
signal. The resultant spectrum was of sufficient quality to allow the
detection of emission lines with an integrated flux of 10-15
ergs/sq cm(sec) or greater. Lines of C I, O I, O V, Cl I, and Fe XXI
were detected. This is the first indisputable detection of the 1354
A Fe XXI line, formed at T approximately = 107 K, on a
star other than the Sun. The line was well resolved and displayed
no significant bulk motions or profile asymmetry. From the upper
limit on the observed line width, we derive an upper limit of 38 km/s
for the turbulent velocity in the 107 K plasma. An upper
limit is derived for the flux of the 1349 A Fe XII line, formed at T
approximately = 1.3 x 106 K. These data are combined with
contemporaneous GHRS and International Ultraviolet Explorer (IUE) data
to derive the volume emission measure distribution of AU Mic over the
temperature range 104-107 K. Models of coronal
loops in hydrostatic equilibrium are consistent with the observed
volume emission measures of the coronal lines. The fraction of the
stellar surface covered by the footprints of the loops depends upon the
loop length and is less than 14% for lengths smaller than the stellar
radius. From the upper limit to the estimated width of the Fe XXI line
profile we find that the we cannot rule out Alfven wave dissipation
as a possible contributor to the required quiescent loop heating rate.

---------------------------------------------------------
Title: Search for CO Absorption Bands in IUE Far-Ultraviolet Spectra
of Cool Stars
Authors: Gessner, S. E.; Carpenter, K. G.; Robinson, R. D.
1994AJ....107..747G Altcode:
Observations of the red supergiant (M2 Iab) alpha Ori with the Goddard
High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope
(HST) have provided an unambiguous detection of a far-ultraviolet
(far-UV) chromospheric continuum on which are superposed strong
molecular absorption bands. The absorption bands have been identified
by Carpenter et al. (1994) with the fourth-positive A-X system of
CO and are likely formed in the circumstellar shell. Comparison of
these GHRS data with archival International Ultraviolet Explorer
(IUE) spectra of alpha Ori indicates that both the continuum and
the CO absorption features can be seen with IUE, especially if
multiple IUE spectra, reduced with the post-1981 IUESIPS extraction
procedure (i.e., with an oversampling slit), are carefully coadded
to increase the signal to noise over that obtainable with a single
spectrum. We therefore initiated a program, utilizing both new and
archival IUE Short Wavelength Prime (SWP) spectra, to survey 15 cool,
low-gravity stars, including alpha Ori, for the presence of these two
new chromospheric and circumstellar shell diagnostics. We establish
positive detections of far-UV stellar continua, well above estimated
IUE in-order scattered light levels, in spectra of all of the program
stars. However, well-defined CO absorption features are seen only in
the alpha Ori spectra, even though spectra of most of the program stars
have sufficient signal to noise to allow the dectection of features of
comparable magnitude to the absorptions seen in alpha Ori. Clearly if
CO is present in the circumstellar environments of any of these stars,
it is at much lower column densities.

---------------------------------------------------------
Title: A Search For Microflaring Activity on dMe Flare Stars
Authors: Robinson, R. D.; Carpenter, K. G.; Percival, J. W.
1994ASPC...64..456R Altcode: 1994csss....8..456R
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: Coordinated Space and Ground-Based Observations of the Flare
Star YZ CMi
Authors: Carpenter, Kenneth G.
1994iue..prop.4768C Altcode:
We propose IUE ultraviolet observations of the flare star YZ CMi to
complement high time resolution data to be acquired with the Goddard
High Resolution Spectrograph on Hubble Space Telescope and other
ground and space-based observatories including the AAT, ROSAT, and
EUVE. The HST observations are designed to search for the signature
of downflowing proton beams during flare events and to estimate their
importance in providing the energy that powers the flare. These IUE
observations, which include the full range of transition region and
chromospheric lines, are critical to determining the energy balance
and atmospheric structure of any flare observed. The extended dataset,
including non-flare spectra, will allow us to characterize the overall
activity level of the star at the time of the observations, and thus
place the events in the proper context.

---------------------------------------------------------
Title: The Chromosphere of Alpha Tau - Cycle 4 Medium
Authors: Carpenter, Kenneth
1994hst..prop.5358C Altcode: 1994hst..prop.1804C
We propose observations of the K5 III star Alpha Tau using the Goddard
High-Resolution Spectrograph (GHRS), to follow-up on the exciting
initial SAO observations of this star and the SV observations of the
K5 III hybrid star Gamma Dra. These data will also allow a detailed
comparison of its spectrum and the thermodynamic properties of its
outer atmosphere with those of the cooler M giant and supergiant
stars Gamma Cru and Alpha Ori, observed during previous cycles. We
shall check for variations in the C II downflow discovered in the
SAO observations and search for evidence of systematic flows in
other emission lines. We shall make detailed comparisons of the
chromospheric emission lines and wind signatures in the UV spectra
of two stars of the same spectral class, where one is a hybrid and
one is not. We shall search for evidence of shocks and/or propagating
waves in the line variations predicted by our recent calculations. We
will also determine the variation of wind velocity with height using
semi-empirical non-LTE models assuming spherical symmetry, search for
evidence of circumstellar and interstellar absorptions on resonance
lines of O I, Fe II, and Mg II, and compare the short-wavelength
continuum measured in this star with that detected in observations of
Gamma Dra, Gamma Cru and Alpha Ori.

---------------------------------------------------------
Title: Spectra and Chromospheres of Carbon and M Stars - CYCLE4 Medium
Authors: Carpenter, Kenneth
1994hst..prop.5359C Altcode: 1994hst..prop.1805C
We propose to use the Faint Object Spectrograph (FOS) and the Goddard
High-Resolution Spectrograph (GHRS) on the HST to obtain ultraviolet
spectra of visually bright N-type carbon stars and late M-giant
stars. These spectra, obtainable only with HST, will be used with
theoretical models to infer the temperature and density structure and
the velocity fields of the outer atmosphere in these evolutionarily
advanced, non-mira giants. In anticipation of this effort, we have
already pushed IUE to its limit to obtain both low-resolution, and,
where possible, high-resolution spectra of several M, S, and C stars,
and these have been analyzed and published. Based upon the observed
line profiles and continua, we will construct semi-empirical non-LTE
models in both plane-parallel geometry and spherical geometry, including
velocity fields, by attaching a chromosphere to theoretical photospheric
models. Two-component models will be studied. Using these and ab-initio
hydrodynamic models, we will examine the mechanisms responsible
for chromospheric heating and mass loss. A full range of supporting
ground-based observations will be undertaken to permit us to connect
models of the photospheres, chromospheres, and circumstellar shells.

---------------------------------------------------------
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: A Search for Proton Beams during Flares on AU Microscopii
Authors: Robinson, R. D.; Carpenter, K. G.; Woodgate, B. E.; Maran,
S. P.
1993ApJ...414..872R Altcode:
We report the results of a coordinated observing campaign on the active
M dwarf star AU Mic. The purpose of the campaign was to search for
evidence of proton beams during the impulsive phase of stellar flares
and to determine whether the energy contained in these beams represented
a significant fraction of the energy budget of the flare. During a total
of 3.5 hr of monitoring a small flare was observed simultaneously by
the HST, IUE, and the AAT. This event, which had a total optical + UV
emission of 1.3 x 10 exp 32 ergs, occurred during the decay phase of
a much larger event and showed no evidence for a proton beam with an
energy greater than a few times 10 exp 29 ergs/s. This is comparable
to the maximum energy flux released by the flare, though this energy
release rate must occur over a time interval much shorter than that
of the impulsive phase itself. We conclude that the proton beams may
be capable of transporting some energy during the impulsive phase
of a flare, but that they are unlikely to be the major contributor,
at least for this particular event.

---------------------------------------------------------
Title: GHRS Observations of the M-giant gamma CRU
Authors: Carpenter, K.; Robinson, R.; Gessner, S.
1993AAS...182.4613C Altcode: 1993BAAS...25..875C
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space
Telescope has been used to obtain medium (R=20,000) and high (R=85,000)
resolution UV spectra of chromospheric emission features for the M3.4
III star gamma Cru. Large Science Aperture (LSA), medium resolution
spectra were obtained to survey the 1980 - 2200 Angstroms region with
good signal-to-noise. Small Science Aperture (SSA) G270M and Echelle-B
spectra of selected longer wavelength regions were obtained to allow
the measurement of velocity flows and turbulence for a variety of ions,
including C II, Fe II, Co II, Si I/II, Ni II, Mn II, and Mg II. Gaussian
fits to the optically thin C II (UV 0.01) intercombination lines and
fluorescently-excited lines of Co II, Ni II, Fe II, and Si I indicate
average turbulent velocities (Doppler FWHM) of 30.2 and 28.6 km/s,
respectively. For comparison, the C II turbulent velocity previously
measured for the K5 giant alpha Tau is ~ 24 km/s. The measured radial
velocities of the fluorescent lines average 21.5 km/s, which places them
basically at rest relative to the radial velocity of the star (21 km/s),
while the C II lines average 23.1 km/s, a modest inflow of a couple of
km/s. A subset of the collisionally-excited Fe II emission lines show
an average radial velocity of 22.6 km/s, also a very modest inflow,
at best. The stronger Fe II lines exhibit a more complex profile which
consists of a broad emission line with an ~ 40 km/s FWHM, on which are
superposed two absorption components. The stronger component appears at
relatively low radial velocity (in the 7 - 15 km/s range) in each line,
with a mean value over the sample of ~ 10.5 km/s, while the weaker
component appears at relatively high radial velocity in each line (in
the range from 25 to 34 km/s), with a mean value of ~ 31.3 km/s. The
first represents an outflow of about 10 km/s, while the second an
inflow of about 10 km/s. The Mg II h and k emission lines also show
the dual-absorption structure seen in the Fe II lines. However, both
the emission and absorption components in the k-line are red-shifted
by 7 to 9.5 km/s, relative to their equivalent components in the h-line.

---------------------------------------------------------
Title: MG II H and K Profiles in Luminous, Cool Stars
Authors: Robinson, R. D.; Carpenter, K. G.
1993AAS...182.4619R Altcode: 1993BAAS...25..877R
As part of an investigation of the velocity fields in the atmospheres of
cool, luminous stars we used the Goddard High Resolution Spectrograph
(GHRS) aboard the Hubble Space Telescope to obtain a high resolution
spectrum of the Mg II h and k lines in the M supergiant alpha Ori. These
strong, centrally reversed emission lines have been well studied by the
IUE. While the h line in alpha Ori has nearly equal intensity in the red
and blue peaks, the blue peak of the k line is always much weaker than
the red peak. This asymmetry is normally explained as resulting from
absorption by Fe I and Mn I in the circumstellar shell. An examination
of the GHRS spectrum, however, reveals that the asymmetry results from
a velocity shift between the emission wings and the central absorption
core of the line. Further, while the central absorption profiles for
the h and k lines agree very well when plotted on a velocity scale, the
centroid of the k line emission wings was observed to be redshifted by
approximately 23 km/s with respect to that of the h line. Examination
of other high resolution GHRS observations of Mg II showed a similar,
though less pronounced, relative redshift of the k line centroid on
the normal M giant gamma Cru and the hybrid K giant gamma Dra. To date,
no concrete model has been proposed to explain these shifts. Examining
well exposed, high resolution IUE observations of alpha Ori shows a
close agreement with the GHRS results. This gives us confidence that
we can use IUE spectra to study the relative shapes and velocities
of the Mg II h and k lines and we are currently involved in a program
to use the IUE archive to quantify the behavior of the Mg II h and k
profiles as a function of luminosity and spectral type for luminous,
cool stars. The results of this program will be presented.

---------------------------------------------------------
Title: A Search for CO Absorption Bands in IUE Spectra of Cool Stars
Authors: Gessner, S.; Carpenter, K.; Robinson, R.
1993AAS...182.4612G Altcode: 1993BAAS...25..875G
Observations of the red supergiant (M2 Iab) alpha Ori with the Goddard
High Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope
(HST) have provided an unambiguous detection of a far-UV continuum on
which are superposed strong molecular absorption bands (Carpenter 1991,
ASP Conf. Ser. 26, p. 17). The continuum is formed in the stellar
chromosphere. The absorption bands, which appear in the 1300 - 1600
Angstroms spectral region, have been identified with the (n,0) bands
(n=0,...,8) of the 4th-positive A-X system of CO and are likely
formed in the circumstellar shell. Comparison of these GHRS data
with archival IUE spectra indicates that both the continuum and the
CO absorption features can be seen with IUE, especially if multiple
IUE spectra, reduced with the post-1981 IUESIPS extraction procedure
(i.e., with an oversampling slit), are carefully co-added to increase
the signal-to-noise over that obtainable with a single spectrum. We
have therefore begun a program, utilizing both new and archival IUE
spectra, to survey other cool, low-gravity stars for the presence of
these two new chromospheric and circumstellar shell diagnostics. We hope
to identify promising targets for examination with HST spectrographs
at the higher resolution and signal-to-noise needed for quantitative
analysis. The initial results of this IUE survey are presented here.

---------------------------------------------------------
Title: Observations of 3C 273 With the Goddard High Resolution
Spectrograph on the Hubble Space Telescope
Authors: Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, E. A.;
Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone,
D. S.; Linsky, J. L.; Maran, S. P.; Savage, B. D.; Smith, A. M.;
Trafton, L. M.; Walter, F. M.; Weymann, R. J.; Snow, M.; Randall,
C. E.; Lindler, D. J.; Shore, S. N.; Morris, S. L.; Gilliland, R. L.;
Lu, L.; Robinson, R. D.
1993AJ....105..831B Altcode:
The observations of the quasar 3C 273 taken with the Goddard High
Resolution Spectrograph in 1991 February are presented here. We have
included both the reduced raw data, and smoothed and deconvolved
spectra. Also, a list of observed absorption lines is presented. The
data comprise 11 spectra, including 1 low resolution observation and 10
medium resolution observations. The wavelength region covered ranged
from about 1150 to 2820 A, but was not all inclusive. The procedures
used to obtain and reduce the data, including corrections for fixed
pattern noise, compensation for the effects of spherical aberration
in the HST primary mirror, and objective detection of weak absorption
lines, are described. We also have included a short discussion on the
detection of galactic Ni II and Virgo cluster metal lines.

---------------------------------------------------------
Title: Atomic data needs for the analysis of the ultraviolet spectrum
of cool stars.
Authors: Carpenter, K. G.
1993PhST...47..139C Altcode:
A brief introduction to the UV spectra of cool stars is given, followed
by a review of astronomical observatories and instruments which
are capable of acquiring UV spectral data on cool stars. Examples
of observational data are presented, along with a description of
typical analysis performed on such data. The basic atomic data needed
to perform these analysis are summarized, with the most important UV
multiples or transitions of the most relevant ions identified.

---------------------------------------------------------
Title: CO Molecular Absorption in Far-UV Spectra of Cool Stars
Authors: Carpenter, Kenneth G.
1993iue..prop.4498C Altcode:
We propose a far-UV survey of cool giant and supergiant stars to search
for evidence of circumstellar absorption by the CO molecule. This
survey is motivated by the discovery of a far-UV continuum and
superposed circumstellar CO absorption in a spectrum of alpha Ori (M2
Iab) obtained with HST and the subsequent demonstration that IUE is
capable of detecting these bands. These bands are an excellent probe
of the circumstellar regions of such stars, and provide diagnostics
of layers not well sampled by other techniques. Where possible, very
rough estimates of the conditions in the regions represented by the CO
absorption will be obtained on the basis of these IUE data. The results
of this survey will then be used to select targets /individual bands
for observation at higher resolution with the GHRS/HST to allow detailed
comparison with models and more precise determinations of temperatures
and column densities in the circumstellar environment of these stars.

---------------------------------------------------------
Title: Observations of a Flare on AU MIC
Authors: Robinson, R. D.; Carpenter, K. G.; Woodgate, B. E.
1992AAS...181.5104R Altcode: 1992BAAS...24.1206R
We report the results of a coordinated observing campaign of the active
dMe flare star AU Mic, carried out on 1992 Sept 9. Participating
instruments include the HST and IUE satellites and the 3.9m
Anglo-Australian Telescope. During this campaign a long duration,
1.5 mag (U band) flare was detected, with the maximum phase observed
simultaneously with the IUE and AAT and the decay phase monitored by
all three instruments. The AAT observations consisted of a time series
of CCD exposures covering the wavelength range 3650-4450 Angstroms
and having a temporal resolution of 6 seconds. The impulsive phase
lasted for about 1 minute and was therefore well resolved by these
observations. The flare showed pronounced broadening of the Balmer
series, with the Balmer line fluxes increasing with the continuum
during the impulsive phase but having a much longer decay time. A
pronounced HeII (4026 Angstroms ) emission was seen during the flare,
with some indication that this line increased in absorption strength
about 30 seconds before the continuum increase. The CaII H and K lines
decreased in strength during the impulsive and early decay phase of the
event, but recovered during the later decay phase. A low resolution LWP
exposure was taken by the IUE during the peak of the flare. Combining
this with the optical data gives an almost complete coverage of the
flare spectrum from 2200 to 4500 Angstroms . We discuss the implications
of these observations in relation to current flare models.

---------------------------------------------------------
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: Detection of a Proton Beam during the Impulsive Phase of a
Stellar Flare
Authors: Woodgate, Bruce E.; Robinson, Richard D.; Carpenter, Kenneth
G.; Maran, Stephen P.; Shore, Steven N.
1992ApJ...397L..95W Altcode:
A transient event consistent with the predicted temporal and spectral
signatures of an energetic proton beam was detected in the impulsive
phase of a small flare on the red dwarf star AU Microscopii. It
consisted of a prominent increase in the flux in the red wing of
Lyman-alpha near 1223 A, simultaneously with the peak of a flare
observed in the 1206 A transition region line of Si III. The probability
that the red wing event was a chance fluctuation is one chance in
2.5 x 10 exp 4. This observation represents a confirmation of the
prediction by Orrall and Zirker (1976) in which downstreaming protons
accelerated during the impulsive phase of a flare charge exchange with
ambient neutral hydrogen and emit Lyman-alpha radiation from 1 to 15
A redward of line center.

---------------------------------------------------------
Title: The Ultraviolet Photospheric Spectrum of Alpha Orionis
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
1992AAS...18110010W Altcode: 1992BAAS...24.1280W
No abstract at ADS

---------------------------------------------------------
Title: Plasma Flows in the Outer Atmosphere of α Ori
Authors: Carpenter, K.; Robinson, R.; Wahlgren, G.; Brandt, J.;
Linsky, J.; Ebbets, D.; Weymann, R.
1992AAS...181.5111C Altcode: 1992BAAS...24.1207C
No abstract at ADS

---------------------------------------------------------
Title: Detection of a Proton Beam during the Impulsive phase of a
Stellar Flare
Authors: Woodgate, B. E.; Robinson, R. D.; Carpenter, K. G.; Maran,
S. P.; Shore, S.
1992AAS...180.3010W Altcode: 1992BAAS...24..777W
We present evidence for the detection of a proton beam during the
impulsive phase of a flare on the Dme star AU Microscopii. At 1991
Sept 3 04h 56m 10s UT, the Goddard High Resolution Spectrograph on the
Hubble Space Telescope observed an increase in the flux in the red
wing of the hydrogen Lyman alpha line at 1223A, unaccompanied by an
increase in the blue wing, simultaneously with an increase in the flux
of the SiIII 1206A transition region line. The 1223A flux increase was
2.2 x 1027 ergs s-1 A-1, with 3s duration. The chance probability of
the observation is 1 in 105. This effect was predicted by Orrall and
Zirker (1976), as a downstreaming beam of protons charge exchanging
with ambient neutral hydrogen and emitting Lyman alpha radiation at
the downstreaming velocity. The energy in the beam is estimated as 7
x 1029 ergs s-1.

---------------------------------------------------------
Title: A Search for Short-Timescale Variations in the Chromosphere;
UV Spectrum of the M-Giant Gamma Crucis
Authors: Cheng, K. -P.; Carpenter, K. G.
1992ASPC...26...43C Altcode: 1992csss....7...43C
No abstract at ADS

---------------------------------------------------------
Title: The Chromosphere and Circumstellar Shell of α Orionis as
Observed with the Goddard High Resolution Spectrograph
Authors: Carpenter, K. G.; Robinson, R. D.; Wahlgren, G. M.; Linsky,
J. L.; Brown, A.
1992ESOC...44..387C Altcode: 1992swhs.conf..387C
No abstract at ADS

---------------------------------------------------------
Title: Detection of a Proton Beam during the Impulsive Phase of a
Stellar Flare
Authors: Robinson, R. D.; Woodgate, B. E.; Carpenter, K. G.; Maran,
S. P.; Shore, S. N.
1992ESOC...44..447R Altcode: 1992swhs.conf..447R
No abstract at ADS

---------------------------------------------------------
Title: Late-Type Stars (Invited Review)
Authors: Carpenter, K. G.
1992ASPC...26...17C Altcode: 1992csss....7...17C
No abstract at ADS

---------------------------------------------------------
Title: A Search for CO Molecular Absorption in Far-UV Spectra of
Cool Stars
Authors: Carpenter, Kenneth G.
1992iue..prop.4214C Altcode:
We propose a far-UV survey of cool giant and supergiant stars to search
for evidence of circumstellar absorption by the CO molecule. This
survey is motivated by the discovery of a far-UV continuum and
superposed circumstellar CO absorption in a spectrum of alpha Ori (M2
lab) obtained with HST and the subsequent demonstration that IUE is
capable of detecting these bands. These bands are an excellent probe
of the circumstellar regions of such stars, and provide diagnostics
of layers not well sampled by other techniques. Where possible, very
rough estimates of the conditions in the regions represented by the CO
absorption will be obtained on the basis of these IUE data. The results
of this survey will then be used to select targets/individual bands for
observation at higher resolution with the GHRS/HST to allow detailed
comparison with models and more precise determinations of temperatures
and column densities in the circumstellar environment of these stars.

---------------------------------------------------------
Title: HST Observations of the Flare Star AU MIC
Authors: Robinson, R. D.; Shore, S. N.; Carpenter, K. G.; Woodgate,
B. E.; Maran, S. P.; Brandt, J. C.; Kundu, M. R.; White, S. M.;
Linsky, J. L.; Walter, F. M.
1992ASPC...26...31R Altcode: 1992csss....7...31R
No abstract at ADS

---------------------------------------------------------
Title: Molecular Absorption in the UV Spectrum of A ORI
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
1992ASPC...26...37W Altcode: 1992csss....7...37W
No abstract at ADS

---------------------------------------------------------
Title: Chromospheres and winds of cool stars
Authors: Carpenter, K. G.
1992HiA.....9..477C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Simultaneous IUE/HST-GHRS Observations of AU MIC
Authors: Carpenter, Kenneth G.
1992iue..prop.4212C Altcode:
We propose to monitor the early dwarf-M flare star and BY Dra
variable AU Mic over two IUE shifts approximately centered on the
time of HST observations with the GHRS. The GHRS observations are
part of a Cycle 1 HST GO program that is to be reexecuted in late
summer of 1992, due to an intermittent HST instrument failure during
the initial execution of the HST program in September 1991. The GHRS
observations cover a single, very narrow range of wavelengths (36 A)
containing Lyman-alpha, Si III 1206 A, and O V 1218 A. They will be
obtained at very high time resolution (0.4 sec/integration) and are
designed to look for evidence of proton downflow during the impulsive
phase of a flare. We request simultaneous IUE observations to place
the HST observations in a broader context, which will include a wider
variety of chromospheric and transition region lines and their behavior
over a 16 hour period approximately centered on the time of the GHRS
observations. IUE data is critically needed during flare detections
by HST, so that the radiative losses in the UV can be estimated and
compared to the energy carried in the proton downflow, in order to
evaluate the importance of this energy source to the flare.

---------------------------------------------------------
Title: Zeta-Aurigae Type Binaries
Authors: Carpenter, K. G.
1992IAUS..151...51C Altcode:
No abstract at ADS

---------------------------------------------------------
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: An Investigation of the Flare Star AU Mic with the Goddard
High Resolution Spectrograph on the Hubble Space Telescope
Authors: Maran, S. P.; Woodgate, B. E.; Carpenter, K. G.; Robinson,
R. D.; Shore, S. N.; Linsky, J. L.; Brown, A.; Byrne, P. B.; Kundu,
M. R.; White, S.; Brandt, J. C.; Shine, R. A.; Walter, F. M.
1991BAAS...23.1382M Altcode:
No abstract at ADS

---------------------------------------------------------
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: Molecular Absorption in the Ultraviolet Spectrum of Alpha Ori
Authors: Wahlgren, G. M.; Robinson, R. D.; Carpenter, K. G.
1991BAAS...23.1386W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Time Resolved Observations of the Lyman-Alpha Region in AU
Mic with the Goddard High Resolution Spectrograph
Authors: Woodgate, B. E.; Maran, S. P.; Carpenter, K. G.; Robinson,
R. D.; Shore, S. N.; Linsky, J. L.; Byrne, P. B.; Kundu, M. R.
1991BAAS...23.1383W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: First Results from the Goddard High-Resolution Spectrograph:
The Chromosphere of alpha Tauri
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Wahlgren,
Glenn M.; Ake, Thomas B.; Ebbets, Dennis C.; Linsky, Jeffrey L.;
Brown, Alexander; Walter, Frederick M.
1991ApJ...377L..45C Altcode:
The K5 III star Alpha Tau was observed with the Goddard High Resolution
Spectrograph on November 27, 1990 as part of the Science Assessment
Program for the HST. The spectra show intersystem and permitted
chromospheric emission lines of semiforbidden C II and Si II, Fe II,
Fe I, Ni II, and Co II. Resolved profiles of the semiforbidden C II
lines indicate a complex chromospheric turbulent velocity distribution
with mean value of roughly 24 km/s, while their observed wavelengths
indicate a 4 km/s downflow of the semiforbidden C II plasma. Twenty-five
new emission lines have been found in the 2320-2370 A region, 17 of
which have been identified with the aid of Skylab data obtained above
the solar limb, including four lines from Co II (UV 8) and an Fe I
(UV 12) line.

---------------------------------------------------------
Title: Physical Conditions and Velocity Structures in the Red Giant
Winds in the Binaries CI CYG and EG and -- Cycle 2
Authors: Carpenter, Kenneth
1991hst..prop.3934C Altcode:
This proposal represents a two pronged attack aimed at understanding the
detailed chracteristics of red giant winds in binary star systems. Red
giant winds can provide the most massive, sustained form of mass
transfer in binaries. The symbiotic and related stars, which contain
red giant and hot companion stars, permit line of sight studies through
a range of red giant atmospheric heights. The goal of this work is to
attempt to define both the mechanism of rapid mass loss in red giant
stars and the details of mass transfer to the companion stars. Such
results can provide important constraints for both stellar and binary
evolution theories. In each case we expect to derive density and
temperature values for the red giant wind region and compare this to the
present understanding of single star conditions where low temperature,
dust and molecule forming, circumstellar envelopes prevail.

---------------------------------------------------------
Title: Revised Faint Target/bright Neighbor Test
Authors: Carpenter, Kenneth
1991hst..prop.3416C Altcode:
Verify capability of HRS to detect weak emission despite immediate
proximity of a bright source. Measure near-angle scattering into HRS
apertures from adjacent bright source. Revised July 24, 1991 by DCE
to complete sequences lost during April 91 execution when carrousel
safed. Revised March 1992 BY DCE for SSA G160M 1300 only

---------------------------------------------------------
Title: GHRS Spectroscopy of Cool Stars. II.
Authors: Brown, A.; Linsky, J.; Carpenter, K.; Robinson, R.; Ebbets, D.
1991BAAS...23R.910B Altcode: 1991BAAS...23..910B
No abstract at ADS

---------------------------------------------------------
Title: GHRS Far-Ultraviolet Spectra of the Coronal Giant Capella
Binary
Authors: Linsky, J. L.; Brown, A.; Carpenter, K.; Robinson, R.
1991BAAS...23..910L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: GHRS Spectroscopy of Cool Stars. I.
Authors: Carpenter, K.; Robinson, R.; Ebbets, D.; Brown, A.; Linsky, J.
1991BAAS...23..910C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: GHRS / Goddard High Resolution Spectrograph / Far Ultraviolet
Spectra of Coronal and Noncoronal Stars - Capella and Gamma-Draconis
Authors: Linsky, J. L.; Brown, A.; Carpenter, K. G.
1991fyho.conf...70L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ghrs/ Goddard High Resolution Spectroscopy Chromospheric
Emission Line Spectra of the Red Giant Alpha-Tauri
Authors: Carpenter, K. G.; Robinson, R. D.; Ebbets, D. C.; Brown,
A.; Linsky, J. L.
1991fyho.conf..212C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Simultaneous IUE/HST-GHRS Observations of AU MIC
Authors: Carpenter, Kenneth G.
1991iue..prop.3944C Altcode:
We propose to monitor the early dwarf-M flare star and BY Dra variable
AU Mic over a two day period centered on the time of HST observations
with the GHRS. The GHRS observations are part of the GHRS Investigation
Definition Teams's Guaranteed Time Observing (GTO) program and are
already approved. The GHRS observations cover a single, very narrow
range of wavelengths (1342 - 1378 A) and their prime purpose is to
detect and measure lines formed in the corona and in coronal flares,
such as Fe XXI 1354 A and Fe XII 1349 A, that are too weak to be
observed by IUE, along with a single transition region line (0 V)
and lines from one chromospheric ion (C 1). We request simultaneous
IUE observations to place the HST observations in a broader context,
which will include a wider variety of chromospheric and transition
region lines and their behavior over a 48 hour period approximately
centered on the time of the GHRS observations. The GHRS observations
are to be scheduled during HST Cycle 0, which (based on a December 1989
launch) covers the period February 15 - July 15, 1990 and could occur
during either the 12th or 13th IUE observing episodes. This proposal
is thus for two years, but all the NASA and ESA shifts are required
to be contiguous and at a time which will overlap the HST observations.

---------------------------------------------------------
Title: Alpha Orionis GHRS Team Project -- Cycle 1
Authors: Carpenter, Kenneth
1990hst..prop.1199C Altcode:
The HRS will be used to obtain high signal/noise spectra of the 1980 -
3300 A spectral region of the M2 Iab supergiant Alpha Orionis. This
full wavelength region will be observed at medium resolution,
while 3 selected wavelength regions will be observed in the echelle
mode. Exposure times have been chosen so that both the chromospheric
emission line spectrum and the photospheric continuum and absorption
line spectrum will be properly exposed. These observations will be
combined and published in atlas format. It is hoped that this atlas
will provide a standard against which high-resolution UV observations
of other late-type stars can be compared. Detailed analysis of these
data are planned by various IDT members.

---------------------------------------------------------
Title: Physical Conditions and Velocity Structures in the Red Giant
Winds in the Binaries CI CYG and EG and -- Repeat for HOPR#67
Authors: Carpenter, Kenneth
1990hst..prop.4251C Altcode:
This proposal represents a two pronged attack aimed at understanding the
detailed chracteristics of red giant winds in binary star systems. Red
giant winds can provide the most massive, sustained form of mass
transfer in binaries. The symbiotic and related stars, which contain
red giant and hot companion stars, permit line of sight studies through
a range of red giant atmospheric heights. The goal of this work is to
attempt to define both the mechanism of rapid mass loss in red giant
stars and the details of mass transfer to the companion stars. Such
results can provide important constraints for both stellar and binary
evolution theories. In each case we expect to derive density and
temperature values for the red giant wind region and compare this to the
present understanding of single star conditions where low temperature,
dust and molecule forming, circumstellar envelopes prevail. (Only EG
And observations are included in this file)

---------------------------------------------------------
Title: Winds and Chromospheres of Cool Luminous Stars -- Cycle 1
Authors: Carpenter, Kenneth
1990hst..prop.3212C Altcode:
The goals of this program are to determine the physical characteristics
of the winds/chromospheres around cool luminous stars. GHRS observations
of the C II (UV 1) 1335 A and (UV 0.01) 2325 A multiplets will be
used along with observations of the C I lines near 1655 and 1994 A to
constrain the temperatures and densities in model chromospheres. The
C II (UV 0.01) lines will also be used to estimate the turbulence
in these chromospheres. The (confusing) far UV spectrum of the M
supergiants will be explored with the GHRS. GHRS observations of Fe
II lines will be used to study the dependence of the wind velocity
on radial distance above the photosphere. High quality Fe II and Mg
II profiles will be acquired to search for discrete velocity features
and the presence of circumstellar absorption within the profiles. The
photospheric absorption-line spectrum (2579-2675 A) of Arcturus will
be observed in the echelle mode. Medium resolution observations of
Fe II and Mg II in the dusty, very luminous star Mu Cep will provide
information on the effect of dust and very low gravity on the wind
velocity field. *** this file contains the Cycle 1 observations only ***

---------------------------------------------------------
Title: The First GHRS Spectra of a Cool Star: The Chromosphere of
Alpha Tau
Authors: Carpenter, K.; Robinson, R.; Ebbets, D.; Linsky, J.; Walter,
F.; Wahlgren, G.; Ake, T.
1990BAAS...22.1277C Altcode:
No abstract at ADS

---------------------------------------------------------
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: 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: Modeling the Ultraviolet Photospheric Spectrum of Cool Giant
Stars - Part Two - Gamma-Crucis
Authors: Wahlgren, G. M.; Carpenter, K. G.
1990ASPC....9...67W Altcode: 1990csss....6...67W
No abstract at ADS

---------------------------------------------------------
Title: Modeling the ultraviolet photospheric spectrum of cool giant
stars. II. Gamma Crucis.
Authors: Wahlgren, G. M.; Carpenter, K. G.
1990ASPC....9...65W Altcode:
The authors present here some results of modeling the spectrum of the
M-giant star γ Cru using similar techniques as those in their study
of Arcturus (Carpenter and Wahlgren, 1990 - see Abstr. 52.114.89).

---------------------------------------------------------
Title: Modeling the Ultraviolet Photospheric Spectrum of Cool Giant
Stars - Part One - Arcturus
Authors: Carpenter, Kenneth G.; Wahlgren, Glenn M.
1990ASPC....9...64C Altcode: 1990csss....6...64C
The UV photospheric spectra of cool giants are modeled analytically
to facilitate the identification of UV spectral features and
aid in the measurement of actual chromospheric flux at different
wavelengths. Atomic line data derived experimentally and semiempirically
are used with LTE model atmospheres by means of the SYNTHE FORTRAN code
to generate the synthetic spectra. Surface flux spectra are determined
and fitted to the absorption features of observed IUE high resolution
spectra, and the modeled results are compared to the observed spectra of
the cool giants Arcturus and the cooler Gamma Crucis. It is shown that
the synthetic spectra can be produced for the stars, and chromospheric
emission lines are thought to account for significant discrepancies
between observed and calculated values. Two new fluorescence mechanisms
are identified by modeling the ultraviolet photospheric spectrum of
Gamma Crucis.

---------------------------------------------------------
Title: Modeling the UV Photospheric Spectrum of K-M Giant Stars
Authors: Carpenter, K.; Wahlgren, G.
1989BAAS...21Q1112C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Evidence for a Cool Wind from the K2 Dwarf in the Detached
Binary V471 Tauri
Authors: Mullan, D. J.; Sion, E. M.; Bruhweiler, F. C.; Carpenter,
K. G.
1989ApJ...339L..33M Altcode:
Evidence for mass loss from the K2 dwarf in V471 Tauri is found in the
form of discrete absorption features in lines of various elements (Mg,
Fe, Cr, Mn) and ionization stages (Mg I, Mg II, Fe I, Fe II). Resonant
Mg II absorption indicates a mass loss rate of at least 10 to the
-11th solar masses per year. The wind appears to be cool (no more than
a few times 10,000 K).

---------------------------------------------------------
Title: Fluorescence in the Outer Atmospheres of Red Giant Stars
Authors: Carpenter, K. G.
1989eprg.proc..372C Altcode: 1989IAUCo.106..372C
No abstract at ADS

---------------------------------------------------------
Title: Far-UV Low Resolution Spectroscopy of High Luminosity K and
M Stars
Authors: Carpenter, Kenneth G.
1989iue..prop.3391C Altcode:
We propose the acquisition of SWP low resolution spectra of K - M bright
giants and supergiants to allow us to: 1) determine the underlying
cause of the extreme weakness of certain fluorescent features, e.g. O
I (UV 2), in the spectrum of a minority of such stars, 2) extend our
emission measure analysis, and thus place improved constraints on the
distribution of the emitting chromospheric plasma with temperature
and density, to lower gravity, cooler effective temperatures, and 3)
estimate the mean relative intensities of the Lyman-alpha and Lyman
Beta lines within the stellar chromospheres. Used in conjunction
with archival data, these spectra will also allow us to determine: 4)
the dependence of radiative loss rates from cool star chromospheres
on Teff and luminosity, 5) whether there is a gradual shift in the
relative importance, to the chromospheric cooling, of higher and lower
temperature species as we go to cooler and more luminous stars, and 6)
whether there is a general trend of increasing flux in fluorescent
species with decreasing effective temperature and increasing
luminosity. In addition, these now spectra will be very valuable
in optimizing the choice of such objects to be observed at higher
resolution and higher signal/noise with the Hubble Space Telescope.

---------------------------------------------------------
Title: Short Timescale Variations in the Outer Atmosphere of Gamma
Crucis
Authors: Carpenter, Kenneth G.
1989iue..prop.3390C Altcode:
We propose the acquisition of a series of UV spectra of the M-giant
Gamma Cru to search for short timescale (i.e. 1 - 10 day) variations in
the chromosphere and UV spectrum of the star. Our primary probes will be
the numerous Fe II lines seen throughout the 2200 - 3200 A region, along
with the Mg II h and k lines and the C II (UV 0.01) intercombination
lines. High resolution line profiles and accurate fluxes will provide
a comprehensive probe of the state (density, temperature) and stability
(velocity field) of the outer atmosphere. The C II lines will be used to
monitor changes in the electron density, while the behavior of the Fe
II and Mg II lines can be used to study changes in the velocity of the
wind versus radius and time. The outward motion of any chromospheric
event will be followed by examining Fe II lines of differing optical
depths, and thus differing formation heights, in the time series. Any
detected variations will provide valuable clues toward understanding
the excitation mechanism(s) of individual Fe II lines, and especially
aid our attempts to distinguish lines dominated by photo-excitation
processes (e.g. Lyman-alpha/Fe II fluorescence) from those primarily
excited by collisions. This latter work will support the goals of 2
major ADP program submitted in the current proposal cycle.

---------------------------------------------------------
Title: The winds of high luminosity late-type bright stars
Authors: Stencel, Robert E.; Carpenter, K. G.
1989gsfc.reptQ....S Altcode:
The occurrence and characteristics of the Fe II line asymmetries
were studied to determine the radial dependence of the wind velocity
for each star. The dependence of the Fe II profiles on spectral type
and luminosity class and thus the variation of the velocity fields
with stellar type was also investigated. This allows the generality
of the results reported for alpha Ori by Carpenter (1984b) to be
judged. In addition, new atomic data was used along with observations
of the C II (UV 0.01) multiplet to estimate Ne in the
stellar winds. Measures of relative Fe II fluxes can be used in a
probability-of-escape model to determine the opacity and hydrogen
column density versus height in the chromosphere of each star. Finally,
analysis of the fluorescent Fe II lines (pumped by Ly alpha) near 2507
A will yield estimates of the intrinsic stellar Ly alpha flux that
cannot be measured directly because of interstellar and circumstellar
absorption. One important goal of the effort was to acquire high
resolution spectra of the whole 2300 to 3200 A region of 13 luminous
K and M stars as a data base that will be enormously valuable in
planning observations with the Hubble Space Telescope High Resolution
Spectrograph. It is also proposed to follow up the recent discovery
of significant variations in the Fe II chromospheric emission line
profiles from the M-giant Gamma Cru for the purpose of determining
the underlying cause of the variations.

---------------------------------------------------------
Title: The Ultraviolet Spectrum of Noncoronal Late-Type Stars:
The Gamma Crucis (M3.4 III) Reference Spectrum
Authors: Carpenter, Kenneth G.; Pesce, Joseph E.; Stencel, Robert E.;
Brown, Alexander; Johansson, Sveneric; Wing, Robert F.
1988ApJS...68..345C Altcode:
A guide is presented to the UV spectrum of M-type giants and supergiants
whose outer atmospheres contain warm chromospheres but not coronae. The
M3 giant Gamma Crucis is taken as the archetype of the cooler,
oxygen-rich, noncoronal stars. Line identifications and integrated
line flux measurements of the chromospheric emission features seen in
the 1200-3200 A range of IUE high-resolution spectra are presented. The
major fluorescence processes operating in the outer atmosphere of Gamma
Crucis, including eight previously unknown pumping processes and 21
new fluorescent line products, are summarized, and the enhancements
of selected line strengths by 'line leakage' is discussed. A set of
absorption features toward the longer wavelength end of this range
is identified which can be used to characterize the radial velocity
of the stellar photospheres. The applicability of the results to the
spectra of noncoronal stars with different effective temperatures and
gravities is discussed.

---------------------------------------------------------
Title: V471 Tauri
Authors: Sion, E. M.; Bruhweiler, F. C.; Carpenter, K.; Mullan, D. J.
1988IAUC.4667....2S Altcode: 1988IAUC.4667....0S
E. M. Sion, Villanova University; F. C. Bruhweiler, Catholic
University of America; K. Carpenter, Goddard Space Flight Center,
NASA; and D. J. Mullan, Bartol Research Institute, report: "IUE
High-Resolution SWP and LWP spectra of the Hyades member V471 Tau
(an eclipsing-spectroscopic, pre-cataclysmic, close binary having
spectral types K2 V + DA2) reveal very-high-velocity, cool, expanding
gas (Fe II, Si II, C II, Mg II, O I), along the line-of-sight to the
binary system, with an expansion velocity of -1200 km/s. There is no
variation of the co-added absorption feature with orbital phase and
its equivalent width is 0.035 nm, with FWHM = 30 km/s. The absorption
appears in seven lines of the Fe II uv1 multiplet (258.5-261.7 nm),
co-added in velocity space for each of the 11 LWP images around the
orbit, in co-added LWP velocity plots of Mg II, Mn II, and Cr II,
as well as in SWP plots of C II (133.5 nm), Si II (126.0 nm), and O I
(130.2 nm), co-added in velocity space. This feature very likely has an
origin distinct from the persistent lower velocity (-500, -260 km/s)
absorption components of the K2 V stellar wind discovered by Mullan
et al. (1988, ESA SP-281, p. 378; Ap.J. Letters, submitted) and from
the narrow co-added feature of C II, Si II, and O I, at -590 km/s
discovered by Bruhweiler and Sion (1986, Ap.J. 202, L45). The large
expansion velocity suggests the possibility of its association with an
ancient nova outburst. Further observations in other wavelength regions,
including deep CCD imaging and direct photography, are strongly urged."

---------------------------------------------------------
Title: Detection of a Cool Wind From the K Dwarf in V471 Tauri
Authors: Mullan, D. J.; Sion, E. M.; Bruhweiler, F.; Carpenter, K.
1988BAAS...20..997M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Far-UV Spectrum of K and M Supergiant Stars
Authors: Carpenter, K. G.
1988BAAS...20..995C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: V471 Tauri: The Oldest and Nearest Old Nova?
Authors: Sion, E. M.; Bruhweiler, F. C.; Carpenter, K.; Mullan, D. J.
1988BAAS...20S1021S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: What does C II lambda 2355 A emission tell us about
chromospheres of red supergiants ? A critical test using dzeta
Aurigae-type K supergiants.
Authors: Schroeder, K. -P.; Reimers, D.; Carpenter, K. G.; Brown, A.
1988A&A...202..136S Altcode:
Line fluxes and intensity ratios of the C II UV 0.01 intercombination
multiplet near λ2325 Å have been used by Carpenter et al. (1985)
to determine the density and the geometric extent of red giant
chromospheres. Here the authors test the limitations of the C II method
and the validity of the assumptions inherent in the method by means of
observations of C II 2325 Å emission of two stars (K type supergiants
ζ Aurigae, 32 Cygni) for which spatially resolved, empirical model
chromospheres has been derived earlier from high resolution IUE
observations at chromospheric eclipse phases (Schröder, 1985).

---------------------------------------------------------
Title: Fluorescence processes and line identifications in the UV
spectra of cool stars (Contributed paper)
Authors: Carpenter, Kenneth G.; Johansson, Sveneric
1988ESASP.281a.349C Altcode: 1988uvai....1..349C; 1988duvb.conf..349C
Fluorescence processes active in the outer atmospheres of noncoronal
cool stars and the UV lines they produce are summarized. Eight
pumping processes and 21 fluorescent line products are discussed. The
processes, which produce 12 lines, involves energy levels not previously
known to be radiatively populated. Four of these are examples of
self-fluorescence, whereby one or more lines of Fe II photo-excite
through coincident lines the upper levels of other Fe II lines lines
seen in emission, while two others explain the selective excitation
of solitary Ni II and Si I lines. Nine of the line products are decays
from levels in Fe I and Fe II already known to be radiatively populated.

---------------------------------------------------------
Title: Identification of new fluorescence processes in the UV spectra
of cool stars from new energy levels of FeII and CrII
Authors: Johansson, Sveneric; Carpenter, Kenneth G.
1988ESASP.281a.361J Altcode: 1988IUE88...1..361J; 1988uvai....1..361J
Two fluorescence processes operating in atmospheres of cool stars,
symbiotic stars, and the Sun are presented. Two emission lines, at
1347.03 and 1360.17 A, are identified as fluorescence lines of Cr
II and Fe II. The lines are due to transitions from highly excited
levels, which are populated radiatively by the hydrogen Lyman alpha
line due to accidental wavelength coincidences. Three energy levels,
one in Cr II and two in Fe II, are reported.

---------------------------------------------------------
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 Goddard High Resolution Spectrograph for the Hubble Space
Telescope: Pre-Launch Status
Authors: Brandt, J.; Ebbets, D.; Carpenter, K.; Heap, S.
1988BAAS...20..677B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Space telescope and the Fe II problem
Authors: Carpenter, Kenneth G.
1988ASSL..138..323C Altcode: 1988IAUCo..94..323C; 1988pffl.proc..323C
The capabilities of the Hubble Space Telescope, especially as they
apply to the "Fe II problem" are reviewed. The major spectroscopic
observing modes of both the Faint Object Spectrograph and the High
Resolution Spectrograph are discussed and compared with those of
the IUE satellite, with a detailed illustrative look at the options
available for observations of Fe II (UV 1) near 2600 Å. Finally, the
major impacts to be expected on astrophysical investigations of Fe II
from the Space Telescope and associated instrumentation are summarized.

---------------------------------------------------------
Title: Dinosaur Bone Beds and Mass Mortality: Implications for the
K-T Extinction
Authors: Carpenter, K.
1988LPICo.673...24C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Far-UV Low Resolution Spectroscopy of M Supergiants
Authors: Carpenter, Kenneth G.
1988iue..prop.3079C Altcode:
We propose the acquisition of SWP low resolution spectra of two M
supergiants. Our emission measure analysis which derive approximate
structure models of the outer atmospheric layers will be extended
to lower gravity, cooler effective temperatures with these data. In
combination with archive data, these spectra will be used to determine:
1) the dependence of radiative loss rates from cool star chromospheres
on Teff and luminosity, 2) whether there is a gradual shift in the
relative importance, to the chromospheric cooling, of higher and
lower temperature species as we go to cooler and more luminous stars,
3) whether there is a general trend of increasing flux in fluorescent
species with decreasing effective temperature and increasing luminosity
and 4) whether the weakness of specific fluorescent lines in Alpha
Ori is a general characteristic of M supergiants or is unique to Alpha
Ori. In addition, these new spectra will be very valuable in optimizing
the choice of such objects to be observed at higher resolution and
higher signal/noise with the Hubble Space Telescope.

---------------------------------------------------------
Title: Fe II emission line profiles in the ultraviolet spectrum of
cool, luminous stars
Authors: Carpenter, Kenneth G.
1988ASSL..138...95C Altcode: 1988IAUCo..94...95C; 1988pffl.proc...95C
The differences between the outer atmospheres of the coronal and
noncoronal cool stars and the importance of massive stellar winds to the
latter group are summarized. The utility of Fe II as a probe of such
winds is indicated and a brief review of previous observations of Fe
II in these stars is given. The early results of a current IUE program
to study the chromospheres and winds of the noncoronal, late-type stars
are presented, including evidence of a strong dependence of the mid-UV
Fe II profiles on stellar luminosity. In addition, the dependence of
the Fe II profiles on intrinsic line strength in spectra of Alpha Ori
and the discovery of a variation of the Fe II profiles with time in
spectra of Gamma Cru are discussed.

---------------------------------------------------------
Title: Emission Line Variations in the UV Spectrum of Gacrux
Authors: Carpenter, K. G.
1987BAAS...19.1026C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observaciones con IUE e IRAS de gigantes y supergigantes rojas.
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
1987RMxAA..14..380H Altcode:
. Previous observations of M giants and supergiants have indicated
that chromospheric Ca II,H and K emission is lacking in stars with high
circumstellar dust-to-gas ratios (Hagen, Stencel, and Dickinson 1983,
Ap. J., 274, 286). Observations with lUE detected other chromospheric
lines (e.g., Mg II, Al II, Fe II) in stars without Ca II emission,
indicating that the dust does not completely quench the . However,
line intensities in dusty stars were reduced. (Carpenter, Stencel, and
Hagen 1986, Ap. J., 308, 859). IRAS observations of visually bright
M giants and supergiants and simple dust shell models indicate that
the 60 and lO0 m excesses can be satisfactorily explained by silicate
grains. Examination of individual IRAS scans indicates spatially
extended emission for the stars R Dor,aOri, W Hya, a Sco, AH Sco, R
Lyr, Cep, PZ Cas and L2 Pup at 60 m. Kay : STARS-CIRCUMSTELLAR SHELLS
- STARS-CHROMOSPHERES

---------------------------------------------------------
Title: The Goddard High Resolution Spectrograph for the Hubble Space
Telescope Status June 1987
Authors: Brandt, J.; Heap, S.; Carpenter, K.; Ebbets, D.; Lindler, D.
1987BAAS...19..757B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A Roadmap to the Ultraviolet Spectrum of Cool, Non-Coronal
Stars
Authors: Carpenter, K. G.; Peace, J.; Stencel, R. E.; Brown, A.
1987BAAS...19..705C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: 119 Tau
Authors: Carpenter, Kenneth
1987iue..prop.2919C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Variations in the Chromosphere and Stellar Wind of Gamma Crucis
Authors: Carpenter, Kenneth G.
1987iue..prop.2752C Altcode:
We propose to follow up the recent discovery of significant variations
in the Fe II chromospheric emission line profiles from the M-giant
Gamma Cru for the purpose of determining the underlying cause of the
variations. The star will be observed at five different times during
the year with SWP low resolution and LWPHI and LWPLO resolution to
determine whether the apparent increase in the opacity of the stellar
wind and chromosphere is: 1) due to additional mass being added to the
outer atmosphere through a one-time ejection of mass or an increase
in the mass loss rate, or 2) due to a temporary or permanent increase
in the chromospheric heating rate, or 3) is a periodic effect due,
for example, to rotation and the resulting variable visibility of
inhomogeneities in the chromosphere. This star is the first single,
non-Mira M-giant for which there is clear evidence from UV lines of
substantial chromospheric variation. It is important that we monitor
the development of this event and attempt to understand its origin,
while the capabilities of IUE are still available to us.

---------------------------------------------------------
Title: Mg II Emission Lines in the Spectra of Cool, High Luminosity
Stars
Authors: Carpenter, Kenneth G.; Stencel, Robert E.; Pesce, Joseph E.
1987LNP...291..164C Altcode: 1987LNP87.291..164C; 1987csss....5..164C
We present the initial results of a survey of the Mg II emission
lines in the spectra of K and M giants, bright giants, and
supergiants. Profiles of the Mg II h and k lines in 12 such stars are
shown in a relative spectral type/luminosity class grid. Plots based
on the h-line data illustrate the existence of a Wilson-Bappu. effect
in these lines and of a slight dependence of the line asymmetry on V-R
color. A time series of Mg II profiles for the M3 giant Gamma Cru show
that the Mg II profiles have not undergone the profile shape changes
seen in the Fe II lines from this star over the same time period.

---------------------------------------------------------
Title: Corrected observed stellar Lyman Alpha profiles for the
effects of interstellar absorption and geocoronal emission
Authors: Neff, J. E.; Linsky, J. L.; Landsman, W. B.; Carpenter, K. G.
1986ESASP.263..669N Altcode: 1986NIA86......669N; 1986niia.conf..669N
Techniques to compensate for interstellar absorption and geocoronal
emission in IUE studies of late stars atmospheres were developed. Thus
it is possible to determine the Lyman alpha flux from nearby cool stars
using the low-resolution spectra in the IUE archives. The accuracy of
such a procedure depends fundamentally upon the assumptions regarding
the shape of the intrinsic profile and the density and velocity
structure of the local interstellar medium, not upon measurement
uncertainties of the low-resolution spectra. Geocoronal emission
and saturated spectra are fatal only to a one-dimensional spectral
analysis. When both the spatial and the spectral dimensions are
considered, the observed Lyman alpha flux can be recovered.

---------------------------------------------------------
Title: Current Status of the High Resolution Spectrograph (HRS)
for the Hubble Space Telescope
Authors: Brandt, J. C.; Carpenter, K. G.; Ebbets, D.; Garner, H.;
Heap, S.; Lindler, D.
1986BAAS...18..940B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Thermal Vacuum Test Results for the Hubble Space Telescope
High Resolution Spectrograph: II. Scientific Performance
Authors: Ebbets, D.; Garner, H.; Carpenter, K. G.; Brandt, J. C.;
Heap, S.; Lindler, D.
1986BAAS...18..940E Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet and Infrared Observations of Stars with
“Quenched” Chromospheres and the Nature of Mass Loss
Authors: Stencel, R. E.; Carpenter, K. G.; Hagen, W.
1986ApJ...308..859S Altcode:
Previous observational evidence implies that the presence of Ca II
emission, a chromospheric indicator, is correlated with the gas/dust
ratio in the envelopes of red giant and supergiant stars. An attempt
is made to determine whether this correlation can be generalized to
all chromospheric activity indicators and the gas/dust ratio. New
ultraviolet observations address the strength of UV emission features
and the fraction of the total chromospheric flux emitted in various
lines. Evidence is found that chromospheres are not completely quenched
in the presence of dust, but that significant alteration of relative
radiative loss patterns may occur. These observations are interpreted
in terms of an instability that converts warm, chromospheric gas into
near-surface dust grains and cool gas capable of supporting molecular
masing. This supports the dust-driven mass loss scenario for red
giant winds.

---------------------------------------------------------
Title: Thermal Vacuum Test Results for the Hubble Space Telescope
High Resolution Spectrograph: I. UV Optical Throughput
Authors: Carpenter, K. G.; Ebbets, D.; Garner, H.; Heap, S.; Lindler,
D.; Brandt, J. C.
1986BAAS...18..940C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Mg II Emission Line Variability of Hybrid Chromosphere Stars
Authors: Brown, A.; Linsky, J. L.; Drake, S. A.; Carpenter, K. G.
1986BAAS...18S.983B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: FeII emission line profiles in spectra of high luminosity,
non-coronal stars
Authors: Carpenter, K. G.
1986ESASP.263...99C Altcode: 1986NIA86.......99C; 1986niia.conf...99C
The results of a program to study the winds of noncoronal late-type
giant and supergiant stars with IUE are presented. The primary data for
this study are profiles, fluxes, and velocities of the Fe II emission
lines which occur throughout the 2200 to 3230 A region of the IUE long
wavelength spectrographs. The apparent dependence of the Fe II profiles
on stellar luminosity (surface gravity) and intrinsic line strength is
discussed. The discovery of significant changes in the Fe II profiles
in spectra of Gamma Crucis (M3 III), during the period 1978 to 1985,
that suggest a substantial change in its outer atmosphere is noted.

---------------------------------------------------------
Title: An IUE High-Dispersion Cool-Star Atlas
Authors: Ayres, T. R.; Brugel, E. W.; Linskyl, J. L.; Brown, A.;
Carpenter, K. G.
1986LNP...254..106A Altcode: 1986csss....4..106A
We are planning to compile a spectral atlas based on high-dispersion
images of representative late-type stars recorded by the International
Ultraviolet Explorer. We solicit advice from the ultraviolet community
concerning how best to present the spectral material.

---------------------------------------------------------
Title: Gamma Crucis
Authors: Carpenter, Kenneth
1986iue..prop.2633C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Optical, UV and Radio Observations of RS Canum Venaticorum
Authors: Catalano, S.; Rodono, M.; Linsky, J. F.; Carpenter, K.;
Gibson, D.; Gary, D.; Butler, J.
1986LNP...254..253C Altcode: 1986csss....4..253C
No abstract at ADS

---------------------------------------------------------
Title: IUE and IRAS observations of luminous M stars with varying
gas-to-dust ratios.
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
1986NASCP2403A...8H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Winds of High Luminosity K and M Stars
Authors: Carpenter, Kenneth G.
1986iue..prop.2426C Altcode:
The winds of high luminosity K and M stars likely play a major role
in stellar evolution, yet this region of the H-R diagram is one of
the least-studied with IUE, due to the very limited number of targets
that are bright in the ultraviolet. However, high-resolution spectra
of the long wavelength region of the few well-observed stars reveal
extremely interesting spectra containing dozens of broad, frequently
self-reversed and asymmetric Fe II emission lines in addition to the
Mg II, Al II, and C II lines seen in all late-type stars. We propose a
comprehensive study of a sample of 13 such stars using both archive and
new observations. We shall study the occurrence and characteristics of
the Fe II line asymmetries to determine the radial dependence of the
wind velocity for each star. We shall also investigate the dependence
of the Fe II profiles on spectral type and luminosity class and thus
the variation of the velocity fields with stellar type. This will
allow us to judge the generality of the results reported for alpha
Ori by Carpenter (1984b). In addition, we shall use new atomic data
along with observations of the C II(UV 0.01) multiplet to estimate Ne
in the stellar winds. Measures of relative Fe II fluxes will be used
in a probability-of-escape model to determine the opacity and hydrogen
column density versus height in the chromosphere of each star. Finally,
analysis of the fluorescent Fe II lines (pumped by Ly-alpha) near
2507 will yield estimates of the intrinsic stellar Ly-alpha flux that
cannot be measured directly because of interstellar and circumstellar
absorption. One important goal of this proposal is to acquire high
resolution spectra of the whole 2300-3200 A region of 13 luminous K and
M stars as a data base that will be enormously valuable in planning
observations with the Space Telescope High Resolution Spectrograph,
which will be able to observe only small portions of the spectrum at
one time with high sensitivity.

---------------------------------------------------------
Title: Efficiency functions for a 316 g/mm echelle grating.
Authors: Cushman, G. W.; Carpenter, K. G.
1986SPIE..627..395C Altcode:
The radiometric response function of the High Resolution Spectrograph
(HRS) for the Hubble Space Telescope was measured in 1984. From the
system efficiency measurements made in the HRS echelle modes, the
relative efficiencies ('ripple' functions) of 14 HRS echelle orders
have been deduced. The results agree well with a theoretical model
of echelle efficiency, except for a residual shift of apparent blaze
angle with spectral order. The discrepancy between nominal and fitted
blaze angle decreases with increasing order number.

---------------------------------------------------------
Title: The Effect of Dust on the Chromospheres of Cool, Luminous Stars
Authors: Carpenter, K. G.; Stencel, R. E.; Hagen, W.
1985BAAS...17..876C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Hydrogen Lyman Alpha Fluxes for Late-Type Dwarf Stars
Authors: Neff, J. E.; Carpenter, K. G.; Ayres, T. R.
1985BAAS...17..879N Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Densities, Temperatures and Geometric Extents of C II Emitting
Regions in the Winds of Luminous, Late-Type Stars
Authors: Carpenter, K. G.; Brown, A.; Stencel, R. E.
1985mlrg.proc...55C Altcode:
The authors summarize techniques for using IUE observations of the
C II UV 0.01 and UV 1 emission line multiplets at 2325 Å and 1335
Å to estimate the electron density (Ne) and temperature
(Te) in, and the geometric extent of, the chromospheres of
late-type stars. The results of applying these techniques to a sample
of 15 stars observed with the IUE satellite are discussed.

---------------------------------------------------------
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: Laboratory Calibration of the High Resolution Spectrograph
for Space Telescope: Absolute Sensitivity
Authors: Carpenter, K. G.; Cushman, G.; Ebbets, D.; Heap, S.;
Brandt, J.
1985BAAS...17..574C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Line identifications, line strengths and continuum flux
measurements in the ultraviolet spectrum of Arcturus.
Authors: Carpenter, K. G.; Wing, R. F.; Stencel, R. E.
1985ApJS...57..405C Altcode:
The ultraviolet spectrum of Arcturus has been observed at high
resolution with the IUE satellite. Line identifications, mean absolute
'continuum' flux measurements, integrated absolute emission-line
fluxes, and measurements of selected absorption line strengths are
presented for the 2250-2930 A region. In the 1150-2000 A region,
identifications are given primarily on the basis of low-resolution
spectra. Chromospheric emission lines have been identified with
low-excitation species including H I, C I, C II, O I, Mg I, Mg II,
Al II, Si I, Si II, S I, and Fe II; there is no evidence for lines of
C IV, N V, or other species requiring high temperatures. A search for
molecular absorption features in the 2500-2930 A interval has led to
several tentative identifications, but only OH could be established as
definitely present. Iron lines strongly dominate the identifications
in the 2250-2930 A region, Fe II accounting for about 86 percent
of the emission features and Fe I for 43 percent of the identified
absorption features.

---------------------------------------------------------
Title: The geometric extent of C II (UV 0.01) emitting regions around
luminous, late-type stars
Authors: Carpenter, K. G.; Brown, A.; Stencel, R. E.
1985ApJ...289..676C Altcode:
A method is presented by which the geometric extent of the chromospheres
around late-type stars can be estimated from measurements of the
total emission-line flux and line ratios within the C II (UV 0.01)
multiplet. Application of this technique to a sample of 15 late-type
stars indicates a clear difference in the radial extent of the
chromospheres around coronal and noncoronal stars. The former stars
appear to have very thin chromospheres (of no more than 0.1 percent of
the photospheric radius), while the latter stars have chromospheres
extending, on average, out to 2.5 photospheric radii. This, in
principle, provides information for understanding structural differences
between late-type giant and supergiant stars with and without coronae,
and could lead to an understanding of the mass-loss mechanisms involved.

---------------------------------------------------------
Title: The structures and spectra of magnetic, line-blanketed model
atmospheres
Authors: Carpenter, K. G.
1985ApJ...289..660C Altcode:
Magnetic, line-blanketed model atmospheres for upper-main-sequence
stars with normal elemental abundances and a slightly distorted
dipolar magnetic field have been constructed. These were computed
with a modified version of the Kurucz ATLAS6 model atmosphere code and
newly computed opacity distribution functions (ODFs), which take into
account the Zeeman splitting of the contributing atomic lines. The
inclusion of magnetic forces changes the structure of an atmosphere
by altering the net gravity and thus the pressure distribution in
the upper layers of the atmosphere. These magnetic forces cause the
structure of the stellar model to vary with latitude and to differ
from the nonmagnetic case. The enhanced blanketing represented by the
'magnetic' ODFS in combination with the structure changes and Zeeman
broadening of individual lines causes the emergent spectrum to vary
with viewing inclination and to differ from the nonmagnetic case. The
structure and spectrum computations are described and results compared
with those for nonmagnetic models. The results are discussed in light
of existing observations of Ap stars, which are thought to have magnetic
field configurations similar to the ones included in these models.

---------------------------------------------------------
Title: The temperature of C II emission-line formation regions in
cool stars.
Authors: Brown, A.; Carpenter, K. G.
1984ApJ...287L..43B Altcode:
An investigation has been conducted of the temperature of C II
emission-line formation regions in the outer atmospheres of late-type
giant and supergiant stars. A distinct dichotomy is seen in the C II
lambda 2325/lambda 1335 ratio between coronal and noncoronal stars. It
is found that C II emission from noncoronal giant and supergiant stars
comes from regions with temperatures of 7000-9000 K, with the mean
temperature being approximately 8500 K, whereas the C II emission
from coronal stars likely comes from hotter regions. The C II ratio
provides a powerful empirical tool for estimating the chromospheric
temperatures of cool giants and supergiants.

---------------------------------------------------------
Title: Chromospheric emission lines in high-resolution LWR spectra
(2200 - 3000 Å) of Gamma Cru (M3 III) and Alpha Ori (M2 Iab).
Authors: Carpenter, K. G.
1984NASCP2349..450C Altcode: 1984fiue.rept..450C; 1984IUE84......450C
The identity and characteristics of the chromospheric emission
features in the 2200 to 300 A region of high resolution spectra of
the stars gamma Cru and alpha Ori are summarized. The velocities,
fluxes, and asymmetries of a set of Fe II lines which share common
upper or lower energy levels are discussed and the information gained
from flux measurements of the C II (UV 0.01) lines is presented. The
Fe II lines in the alpha Ori spectra indicate the general shape of
the velocity versus radius relation in its wind. The C II (UV 0.01)
data are combined with measures of the C II (UV 1) flux to estimate
the electron density and temperature in the wind and the geometric
extent of the C II emitting region in both stars.

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

---------------------------------------------------------
Title: Rotational velocities of later B type and A type stars as
determined from ultraviolet versus visual line profiles.
Authors: Carpenter, K. G.; Slettebak, A.; Sonneborn, G.
1984ApJ...286..741C Altcode:
Theoretical line profiles of the Si III 1299 and Fe II 2756 lines are
computed for rotating B5-A7 model stars, and compared with observed
profiles from IUE spectra to derive rotational velocities. Real
differences in widths for ultraviolet as compared with visual line
profiles exist in the sample of B type stars (but not for the A type
rapidly rotating stars), although these are not as large as previously
reported in the literature. Comparison with the theoretical line
profiles gives rotational velocities that are in good agreement with
visually determined v sin i values for the same stars, which suggests
that the shape-distorted, gravity-darkened models are reasonable.

---------------------------------------------------------
Title: Characteristics of the Fe II and C II emission in
high-resolution IUEspectra (2300-3000 A ) of alpha Orionis.
Authors: Carpenter, K. G.
1984ApJ...285..181C Altcode:
A study is presented of Fe II and C II emission features in the
2300-3000 A region of four high-resolution IUE spectra of Alpha
Ori obtained during the period 1978 April-1982 November. A set of
42 unmutilated, unblended Fe II lines of multiplets UV 1-3, 32-33,
35-36, and 60-64 and the C II (UV 0.01) intercombination lines have
been identified and measured to determine their velocities, fluxes,
and asymmetries. A correlation of Fe II line asymmetry with intrinsic
line strength indicates a velocity field which is initially constant,
then algebraically increases with radius to a maximum value and then
decreases significantly before reaching an asymptotic flow speed far
from the star. The mean velocity of the chromospheric regions emitting
Fe II does not appear to differ substantially from the time-average
of the photospheric velocity, but there is evidence that the two
regions are not strongly coupled and thus that the chromosphere
does not strictly follow the semiperiodic 6 year pulsations of the
photosphere. An analysis of the C II line fluxes produces estimates of
the electron density in the chromosphere in the range 3.2 x 10 to the
7th-1.3 x 10 to the 8th per sq cm and indicates that the region emitting
C II is geometrically thick, extending at least one-tenth, and perhaps
as far as 1.2, photospheric radii from the base of the chromosphere.

---------------------------------------------------------
Title: IUE and IRAS Observations of Luminous M Stars with Varying
Gas-to-Dust Ratios
Authors: Hagen, W.; Carpenter, K. G.; Stencel, R. E.
1984BAAS...16..895H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atmospheric Structures in AR Lac. I. Mapping Quiescent Features
by Occultations &amp;Doppler Imaging
Authors: Walter, F. M.; Gibson, D. M.; Brown, A.; Carpenter, K.;
Linsky, J. L.; Rodono, M.; Eyles, C.
1984BAAS...16R.896W Altcode: 1984BAAS...16..896W
No abstract at ADS

---------------------------------------------------------
Title: Book-Review - Atlas of High Resolution IUE Spectra of Late-Type
Stars 2500-3230A
Authors: Wing, R. F.; Carpenter, K. G.; Wahlgren, G. M.
1984S&T....67R.527W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet spectroscopic observations of some Be stars of
later typeand A-F type shell stars.
Authors: Slettebak, A.; Carpenter, K. G.
1983ApJS...53..869S Altcode:
High-dispersion IUE spectra of 18 later type Be and A-F type shell
stars as well as eight standard nonemission line stars have been
analyzed for anomalous ionization and mass loss effects. It is found
that superionization in the Be stars extends to the latest spectral
subtypes but does not seem to be present in the A-F type stars. The
superionized lines in the Be stars appear to be correlated with v
sin i. Asymmetrical or violet-displaced resonance lines suggesting
mass loss are observed in all the Be stars except one, in some of the
standard stars, but not in the A-F stars. Lower limits to the mass
loss rates computed from Si IV lines range between 5.3 x 10 to the
-12th and 3.5 x 10 to the -11th solar masses/yr, with Be shell stars
showing the largest values. Mass loss is correlated with luminosity
and effective temperature but not with rotation.

---------------------------------------------------------
Title: Characteristics of the Fe II and C II Chromospheric Emission
Lines in Alpha Ori as a Function of Time
Authors: Carpenter, K. G.
1983BAAS...15..966C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atlas of high resolution IUE spectra of late-type stars
2500-3230 A
Authors: Wing, Robert F.; Carpenter, Kenneth G.; Wahlgren, Glenn M.
1983ahri.book.....W Altcode: 1983QB843.C6W56....
No abstract at ADS

---------------------------------------------------------
Title: Measurements of chromospheric densities and geometrical
extensions of late-type giant and super-giant stars
Authors: Wing, R. F.; Carpenter, K. G.; Stencel, R. E.; Linsky, J. L.
1983osuc.rept.....W Altcode:
The density sensitivity of the emission lines within the UV 0.01
multiplet of C II near 2325 A was examined in additional late type
giants and supergiants with deep LWR high dispersion exposures. The
new data support the original contention based on these lines that
noncoronal red giants possess geometrically extended chromospheres.

---------------------------------------------------------
Title: A Study of Magnetic, Line-Blanketed Model Atmospheres.
Authors: Carpenter, K. G.
1983PhDT.........2C Altcode:
Magnetic, line-blanketed model atmospheres for upper main-sequence
stars with normal elemental abundances and a slightly distorted
dipolar magnetic field have been constructed. These were computed with
a modified version of the ATLAS6 (Kurucz, 1979) model atmosphere code
and newly computed Opacity Distribution Functions (ODF's), which take
into account the Zeeman Splitting of the contributing atomic lines. The
calculation of the "magnetic" ODF's is described and the results
are compared with the original non-magnetic Kurucz functions. The
inclusion of magnetic forces changes the structure of an atmosphere
by altering the net gravity and thus the pressure distribution in
the upper layers of the atmosphere. These magnetic forces cause the
structure of the stellar model to vary with latitude and to differ
from the non-magnetic case. The enhanced blanketing represented by
the "magnetic" ODF's in combination with the structure changes cause
the emergent spectrum to vary with viewing inclination and to differ
from the non-magnetic case. The structure and spectra computations are
described and results compared with those for non-magnetic models. The
results are discussed in light of existing observations of Ap stars,
which are thought to have magnetic field configurations corresponding
to the ones included in these models.

---------------------------------------------------------
Title: A study of magnetic, line-blanketed model atmospheres
Authors: Carpenter, Kenneth George
1983PhDT.......177C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Outer atmospheres of cool stars. XII. A survey of IUE
ultraviolet emission line spectra of cool dwarf stars.
Authors: Linsky, J. L.; Bornmann, P. L.; Carpenter, K. G.; Wing,
R. F.; Giampapa, M. S.; Worden, S. P.; Hege, E. K.
1982ApJ...260..670L Altcode:
Quantitative information is obtained on the chromospheres and
transition regions of M dwarf stars, in order to determine how the outer
atmospheres of dMe stars differ from dM stars and how they compare with
the outer atmospheres of quiet and active G and K type dwarfs. IUE
spectra of six dMe and four dM stars, together with ground-based
photometry and spectroscopy of the Balmer and Ca II H and K lines,
show no evidence of flares. It is concluded, regarding the quiescent
behavior of these stars, that emission-line spectra resemble that of
the sun and contain emission lines formed in regions with 4000-20,000 K
temperatures that are presumably analogous to the solar chromosphere,
as well as regions with temperatures of 20,000-200,000 K that are
presumably analogous to the solar transition region. Emission-line
surface fluxes are proportional to the emission measure over the range
of temperatures at which the lines are formed.

---------------------------------------------------------
Title: An Atlas of High-Resolution IUE Spectra of Late-Type Stars
Authors: Wing, R. F.; Carpenter, K. G.; Wahlgren, G. M.
1982BAAS...14..918W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic, Line-blanketed Model Atmospheres
Authors: Carpenter, K. G.
1982BAAS...14..920C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Integrated Fluxes for Emission Lines in the Ultraviolet
Spectra of Several Planetary Nebulae
Authors: Carpenter, K. G.; Czyzak, S. J.
1982Ap&SS..84..495C Altcode:
The IUE satellite observatory has been used to obtain
absolutely-calibrated emission line fluxes for diagnostic lines of
multiply-ionized C, N, O, Si, Ne, and Ar which occur in the ultraviolet
spectral region of planetary nebulae. These data, when combined with
data from the blue, visual, and near infrared, will provide improved
estimates of ionic concentrations, plasma temperatures and densities,
and elemental abundances.

---------------------------------------------------------
Title: Fluorescence in Stellar Chromospheres
Authors: Carpenter, K. G.; Wing, R. F.; Stencel, R. E.
1982BAAS...14..614C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Density sensitive C II lines in cool giant stars.
Authors: Stencel, R. E.; Carpenter, K. G.
1982NASCP2238..243S Altcode: 1982NASCP2338..243S; 1982auva.nasa..243S; 1982IUE82......243S
The density sensitivity of the emission lines within the ultraviolet
0.01 multiplet of C II near 2325 A was examined in additional late type
giants and supergiants with deep LWR high dispersion exposures. The
new data support the original contention based on these lines that
noncoronal red giants posses geometrically extended chromospheres.

---------------------------------------------------------
Title: Integrated fluxes for emission lines in the ultraviolet
spectra of several planetaries
Authors: Carpenter, K. G.; Czyzak, S. J.
1981STIN...8213022C Altcode:
The IUE satellite observatory was used to obtain absolutely-calibrated
emission line fluxes for diagnostic lines of multiply-ionized C,
N, O, Si, Ne, and Ar which occur in the ultraviolet spectral region
of planetary nebulae. These data, when combined with data from the
blue, visual, and near infrared, provide improved estimates of ionic
concentrations, plasma temperatures and densities, and elemental
abundances.

---------------------------------------------------------
Title: Density sensitive C II lines in cool stars of low gravity.
Authors: Stencel, R. E.; Linsky, J. L.; Brown, A.; Jordan, C.;
Carpenter, K. G.; Wing, R. F.; Czyzak, S.
1981MNRAS.196P..47S Altcode:
It is shown that the relative intensities of emission lines within the
multiplet UV 0.01 of C II, around 2325 A, are sensitive to electron
density in the range 10 to the 9th to 10 to the 7th per cu cm. The lines
therefore offer a valuable method for measuring electron densities in
the chromospheres of late-type giants and supergiants. Calculated line
ratios are compared with those observed in a range of objects.

---------------------------------------------------------
Title: Notes on the early-type components of W Cep, omicron Cet,
CH Cyg, AR Mon, and BL Tel.
Authors: Wing, R. F.; Carpenter, K. G.
1981NASCP2171..341W Altcode: 1981uviu.nasa..341W; 1981NASCP3171..341W; 1980IUE80......341W
Low resolution IUE spectra in both spectral regions are used to clarify
the nature of the warmer components of several binary systems. The
W Cep, the primary of which is a luminous K-type supergiant, shows
an ultraviolet absorption spectrum of type B0 or B1; this system is
heavily reddened. The hot companion of Mira (o Cet) is surprisingly
faint in the short wavelength region, but it excites a rich emission
spectrum from the surrounding gas. The ultraviolet active M7 giant
CH Cyg is shown to be a binary with a hot companion. This system was
also observed at high resolution and shows variable Fe II emission
and well-separated circumstellar and interstellar absorptions within
the broad Mg II emission profiles. The eclipsing binaries AR Mon and
BL Tel are shown not to have hot companions.

---------------------------------------------------------
Title: A Search for Technetium in Zeta Cap and Several M star Mira
Variables
Authors: Little-Marenin, I. R.; Little, S. J.; Wing, R. F.; Carpenter,
K. G.; Wallerstein, G.
1980BAAS...12..826L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric Densities and Geometrical Extensions of Red
Giants and Supergiants using C II Lines as Diagnostics
Authors: Stencel, R. E.; Jordan, C.; Wing, R. F.; Linsky, J. L.;
Carpenter, K. G.; Brown, A.; Czyzak, S. J.
1980BAAS...12..806S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An IUE Survey of the Ultraviolet Emission Line Spectra of
dMe and dM Stars
Authors: Carpenter, K. G.; Wing, R. F.; Bornmann, P. L.; Linsky, J. L.
1980BAAS...12..538C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Extension of Line Identifications in Arcturus Shortward
to 2250A
Authors: Carpenter, K. G.; Stencel, R. E.; Wing, R. F.
1980BAAS...12..529C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Survey of the Ultraviolet Spectra of Late-Type Stars
Authors: Carpenter, K. G.; Wing, R. F.
1979BAAS...11..419C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet Spectra of M Stars.
Authors: Wing, R. F.; Carpenter, K. G.
1978BAAS...10..444W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Intercomparisons of Parallaxes from Nine Observatories.
Authors: Upgren, A. R.; Carpenter, K. G.
1977BAAS....9..355U Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An estimate of external errors in parallaxes
Authors: Upgren, A. R.; Carpenter, K. G.
1977AJ.....82..227U Altcode:
The estimate of the external errors in trigonometric paral1axes made
by Hertzsprung is repeated using a nonlinear least-squares procedure
to fit normal distributions to observed frequency distributions in
parallaxes. The best estimate of mean error in parallax is io' 016,
in exact agreement with Hertzsprung; but unlike him, it was made using
only parallaxes listed in the Yale Catalogue determined at a single
observatory. Using the entire catalogue as he did, an error of +0.018
was found, but the smaller value is considered more realistic.

---------------------------------------------------------
Title: Observations of the large Comet
Authors: Burder, W. C.; Stothard, J. M.; Tidmarsh, G. A.; Carpenter
1861MNRAS..21..242B Altcode:
No abstract at ADS