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Author name code: giampapa
ADS astronomy entries on 2022-09-14
author:"Giampapa, Mark" 

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Title: Final Report for SAG 21: The Effect of Stellar Contamination
    on Space-based Transmission Spectroscopy
Authors: Rackham, Benjamin V.; Espinoza, Néstor; Berdyugina, Svetlana
   V.; Korhonen, Heidi; MacDonald, Ryan J.; Montet, Benjamin T.; Morris,
   Brett M.; Oshagh, Mahmoudreza; Shapiro, Alexander I.; Unruh, Yvonne C.;
   Quintana, Elisa V.; Zellem, Robert T.; Apai, Dániel; Barclay, Thomas;
   Barstow, Joanna K.; Bruno, Giovanni; Carone, Ludmila; Casewell, Sarah
   L.; Cegla, Heather M.; Criscuoli, Serena; Fischer, Catherine; Fournier,
   Damien; Giampapa, Mark S.; Giles, Helen; Iyer, Aishwarya; Kopp, Greg;
   Kostogryz, Nadiia M.; Krivova, Natalie; Mallonn, Matthias; McGruder,
   Chima; Molaverdikhani, Karan; Newton, Elisabeth R.; Panja, Mayukh;
   Peacock, Sarah; Reardon, Kevin; Roettenbacher, Rachael M.; Scandariato,
   Gaetano; Solanki, Sami; Stassun, Keivan G.; Steiner, Oskar; Stevenson,
   Kevin B.; Tregloan-Reed, Jeremy; Valio, Adriana; Wedemeyer, Sven;
   Welbanks, Luis; Yu, Jie; Alam, Munazza K.; Davenport, James R. A.;
   Deming, Drake; Dong, Chuanfei; Ducrot, Elsa; Fisher, Chloe; Gilbert,
   Emily; Kostov, Veselin; López-Morales, Mercedes; Line, Mike; Močnik,
   Teo; Mullally, Susan; Paudel, Rishi R.; Ribas, Ignasi; Valenti, Jeff A.
2022arXiv220109905R    Altcode:
  Study Analysis Group 21 (SAG21) of the Exoplanet Exploration Program
  Analysis Group (ExoPAG) was organized to study the effect of stellar
  contamination on space-based transmission spectroscopy, a method for
  studying exoplanetary atmospheres by measuring the wavelength-dependent
  radius of a planet as it transits its star. Transmission spectroscopy
  relies on a precise understanding of the spectrum of the star being
  occulted. However, stars are not homogeneous, constant light sources
  but have temporally evolving photospheres and chromospheres with
  inhomogeneities like spots, faculae, and plages. This SAG has brought
  together an interdisciplinary team of more than 100 scientists, with
  observers and theorists from the heliophysics, stellar astrophysics,
  planetary science, and exoplanetary atmosphere research communities,
  to study the current needs that can be addressed in this context to
  make the most of transit studies from current NASA facilities like
  HST and JWST. The analysis produced 14 findings, which fall into
  three Science Themes encompassing (1) how the Sun is used as our best
  laboratory to calibrate our understanding of stellar heterogeneities
  ("The Sun as the Stellar Benchmark"), (2) how stars other than the Sun
  extend our knowledge of heterogeneities ("Surface Heterogeneities of
  Other Stars") and (3) how to incorporate information gathered for the
  Sun and other stars into transit studies ("Mapping Stellar Knowledge
  to Transit Studies").

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Title: The GAPS programme at TNG. XXII. The GIARPS view of the
    extended helium atmosphere of HD 189733 b accounting for stellar
    activity
Authors: Guilluy, G.; Andretta, V.; Borsa, F.; Giacobbe, P.; Sozzetti,
   A.; Covino, E.; Bourrier, V.; Fossati, L.; Bonomo, A. S.; Esposito,
   M.; Giampapa, M. S.; Harutyunyan, A.; Rainer, M.; Brogi, M.; Bruno,
   G.; Claudi, R.; Frustagli, G.; Lanza, A. F.; Mancini, L.; Pino, L.;
   Poretti, E.; Scandariato, G.; Affer, L.; Baffa, C.; Baruffolo, A.;
   Benatti, S.; Biazzo, K.; Bignamini, A.; Boschin, W.; Carleo, I.;
   Cecconi, M.; Cosentino, R.; Damasso, M.; Desidera, S.; Falcini,
   G.; Martinez Fiorenzano, A. F.; Ghedina, A.; González-Álvarez,
   E.; Guerra, J.; Hernandez, N.; Leto, G.; Maggio, A.; Malavolta, L.;
   Maldonado, J.; Micela, G.; Molinari, E.; Nascimbeni, V.; Pagano, I.;
   Pedani, M.; Piotto, G.; Reiners, A.
2020A&A...639A..49G    Altcode: 2020arXiv200505676G
  Context. Exoplanets orbiting very close to their parent star are
  strongly irradiated. This can lead the upper atmospheric layers to
  expand and evaporate into space. The metastable helium (He I) triplet
  at 1083.3 nm has recently been shown to be a powerful diagnostic
  to probe extended and escaping exoplanetary atmospheres. <BR />
  Aims: We perform high-resolution transmission spectroscopy of the
  transiting hot Jupiter HD 189733 b with the GIARPS (GIANO-B + HARPS-N)
  observing mode of the Telescopio Nazionale Galileo, taking advantage
  of the simultaneous optical+near infrared spectral coverage to detect
  He I in the planet's extended atmosphere and to gauge the impact of
  stellar magnetic activity on the planetary absorption signal. <BR />
  Methods: Observations were performed during five transit events of HD
  189733 b. By comparison of the in-transit and out-of-transit GIANO-B
  observations, we computed high-resolution transmission spectra. We
  then used them to perform equivalent width measurements and carry
  out light-curves analyses in order to consistently gauge the excess
  in-transit absorption in correspondence with the He I triplet. <BR />
  Results: We spectrally resolve the He I triplet and detect an absorption
  signal during all five transits. The mean in-transit absorption depth
  amounts to 0.75 ± 0.03% (25σ) in the core of the strongest helium
  triplet component. We detect night-to-night variations in the He I
  absorption signal likely due to the transit events occurring in the
  presence of stellar surface inhomogeneities. We evaluate the impact of
  stellar-activity pseudo-signals on the true planetary absorption using
  a comparative analysis of the He I 1083.3 nm (in the near-infrared)
  and the Hα (in the visible) lines. Using a 3D atmospheric code, we
  interpret the time series of the He I absorption lines in the three
  nights not affected by stellar contamination, which exhibit a mean
  in-transit absorption depth of 0.77 ± 0.04% (19σ) in full agreement
  with the one derived from the full dataset. In agreement with previous
  results, our simulations suggest that the helium layers only fill part
  of the Roche lobe. Observations can be explained with a thermosphere
  heated to ~12 000 K, expanding up to ~1.2 planetary radii, and losing ~1
  g s<SUP>-1</SUP> of metastable helium. <BR /> Conclusions: Our results
  reinforce the importance of simultaneous optical plus near infrared
  monitoring when performing high-resolution transmission spectroscopy of
  the extended and escaping atmospheres of hot planets in the presence
  of stellar activity. <P />Based on observations made with the Italian
  Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo
  Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the
  Observatorio del Roque de los Muchachos (La Palma, Canary Islands,
  Spain).

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Title: Towards Mitigating the Impact of Stellar Photospheric
    Heterogeneity on Precise Exoplanet Transmission Spectra
Authors: Rackham, Benjamin; Apai, Dániel; Giampapa, Mark; Espinoza,
   Néstor; Madhusudhan, Nikku; Zhou, Yifan
2019EPSC...13..971R    Altcode:
  Exoplanet transmission spectroscopy, the study of spectroscopic transit
  depths, provides our best opportunity to characterize the atmospheres of
  temperate, Earth-sized exoplanets in the next two decades. However, this
  technique is subject to spurious signals introduced by the photospheric
  heterogeneity of exoplanet host stars, which may mimic or mask real
  exoplanetary signals. As the late-type hosts that provide the most
  favorable planet-to-star radius ratios for studying small exoplanets
  also tend to be more photospherically heterogeneous, our ability
  to disentangle stellar and planetary signals represents a possible
  limitation for precise transmission spectroscopy. Here we present
  our recent work to understand the scale of TLS signals with forward
  models and to characterize the photospheres of important exoplanet
  host stars through (1) transit crossings of magnetic active regions,
  (2) joint retrievals of stellar and exoplanetary properties from
  transmission spectra, and (3) stellar photospheric decomposition with
  moderate-resolution visual and near-infrared spectra. Constraining the
  photospheric heterogeneity of exciting exoplanet host stars with these
  approaches will be key to realizing the opportunity to characterize
  Earth-sized exoplanets via transits.

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Title: Constraining Stellar Photospheres as an Essential Step for
    Transmission Spectroscopy of Small Exoplanets
Authors: Rackham, Benjamin; Pinhas, Arazi; Apai, Dániel; Haywood,
   Raphaëlle; Cegla, Heather; Espinoza, Néstor; Teske, Johanna;
   Gully-Santiago, Michael; Rau, Gioia; Morris, Brett M.; Angerhausen,
   Daniel; Barclay, Thomas; Carone, Ludmila; Cauley, P. Wilson; de Wit,
   Julien; Domagal-Goldman, Shawn; Dong, Chuanfei; Dragomir, Diana;
   Giampapa, Mark S.; Hasegawa, Yasuhiro; Hinkel, Natalie R.; Hu, Renyu;
   Jordán, Andrés; Kitiashvili, Irina; Kreidberg, Laura; Lisse,
   Carey; Llama, Joe; López-Morales, Mercedes; Mennesson, Bertrand;
   Molaverdikhani, Karan; Osip, David J.; Quintana, Elisa V.
2019BAAS...51c.328R    Altcode: 2019astro2020T.328R; 2019arXiv190306152R
  Transmission spectra probe the atmospheres of transiting exoplanets, but
  these observations are also subject to signals introduced by magnetic
  active regions on host stars. We outline scientific opportunities in
  the next decade for providing useful constraints on stellar photospheres
  for the purposes of exoplanet transmission spectroscopy.

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Title: The Transit Light Source Effect. II. The Impact of Stellar
    Heterogeneity on Transmission Spectra of Planets Orbiting Broadly
    Sun-like Stars
Authors: Rackham, Benjamin V.; Apai, Dániel; Giampapa, Mark S.
2019AJ....157...96R    Altcode: 2018arXiv181206184R
  Transmission spectra probe exoplanetary atmospheres, but they can
  also be strongly affected by heterogeneities in host star photospheres
  through the transit light source effect. Here we build upon our recent
  study of the effects of unocculted spots and faculae on M-dwarf
  transmission spectra, extending the analysis to FGK dwarfs. Using
  a suite of rotating model photospheres, we explore spot and facula
  covering fractions for varying activity levels and the associated
  stellar contamination spectra. Relative to M dwarfs, we find that the
  typical variabilities of FGK dwarfs imply lower spot covering fractions,
  though they generally increase with later spectral types, from ∼0.1%
  for F dwarfs to 2%-4% for late-K dwarfs. While the stellar contamination
  spectra are considerably weaker than those for typical M dwarfs,
  we find that typically active G and K dwarfs produce visual slopes
  that are detectable in high-precision transmission spectra. We examine
  line offsets at Hα and the Na and K doublets and find that unocculted
  faculae in K dwarfs can appreciably alter transit depths around the
  Na D doublet. We find that band-averaged transit depth offsets at
  molecular bands for CH<SUB>4</SUB>, CO, CO<SUB>2</SUB>, H<SUB>2</SUB>O,
  N<SUB>2</SUB>O, O<SUB>2</SUB>, and O<SUB>3</SUB> are not detectable
  for typically active FGK dwarfs, though stellar TiO/VO features are
  potentially detectable for typically active late-K dwarfs. Generally,
  this analysis shows that inactive FGK dwarfs do not produce detectable
  stellar contamination features in transmission spectra, though active
  FGK host stars can produce such features, and care is warranted in
  interpreting transmission spectra from these systems.

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Title: The Transit Light Source Effect in F to M Dwarf Systems
Authors: Rackham, Benjamin V.; Apai, Dániel; Giampapa, Mark S.;
   Zhang, Zhanbo; Zhou, Yifan
2019AAS...23310302R    Altcode:
  Transmission spectra are powerful probes of exoplanet atmospheres,
  but they are also subject to spectral features introduced by the
  transit light source (TLS) effect. This phenomenon imprints on transit
  depths the contrast between the emergent spectrum of the transit
  chord—the true light source for the transmission measurement—and the
  out-of-transit disk-averaged stellar spectrum—the necessarily assumed
  light source. Here we summarize a series of studies exploring the TLS
  effect in F to M dwarfs. We use a suite of model rotating photospheres
  to determine spot and faculae covering fractions for typical stellar
  activity levels, with which we calculate the corresponding TLS signals
  in transmission spectra. We find that transit depth changes due to the
  TLS effect can be comparable to or even an order of magnitude larger
  than those expected for transiting exoplanets. TLS signals are more
  pronounced in smaller and cooler main sequence stars—the same stars
  that have been the focus of many transit studies, given their favorable
  planet-to-star radius ratios. The TLS effect can mimic or mute H2O
  features from planetary atmospheres in M-dwarf systems and TiO/VO
  features in active late-G- and K-dwarf systems. We will discuss the
  spectral characteristics and scales of TLS signals for F to M spectral
  types and present transmission spectra from two M-dwarf systems that
  show evidence for TLS contamination: the GJ 1214 system (M4.5V) and
  the TRAPPIST-1 system (M8V). Robust methods of disentangling stellar
  and planetary features in transits will be crucial to interpretations
  of high-precision transmission spectra from JWST and future missions.

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Title: Enhanced Stellar Activity for Slow Antisolar Differential
    Rotation?
Authors: Brandenburg, Axel; Giampapa, Mark S.
2018ApJ...855L..22B    Altcode: 2018arXiv180208689B
  High-precision photometry of solar-like members of the open cluster M67
  with Kepler/K2 data has recently revealed enhanced activity for stars
  with a large Rossby number, which is the ratio of rotation period
  to the convective turnover time. Contrary to the well established
  behavior for shorter rotation periods and smaller Rossby numbers,
  the chromospheric activity of the more slowly rotating stars of M67
  was found to increase with increasing Rossby number. Such behavior has
  never been reported before, although it was theoretically predicted
  to emerge as a consequence of antisolar differential rotation (DR)
  for stars with Rossby numbers larger than that of the Sun, because in
  those models the absolute value of the DR was found to exceed that for
  solar-like DR. Using gyrochronological relations and an approximate
  age of 4 Gyr for the members of M67, we compare with computed rotation
  rates using just the B - V color. The resulting rotation-activity
  relation is found to be compatible with that obtained by employing
  the measured rotation rate. This provides additional support for the
  unconventional enhancement of activity at comparatively low rotation
  rates and the possible presence of antisolar differential rotation.

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Title: Understanding Stellar Contamination in Exoplanet Transmission
    Spectra as an Essential Step in Small Planet Characterization
Authors: Apai, Dániel; Rackham, Benjamin V.; Giampapa, Mark S.;
   Angerhausen, Daniel; Teske, Johanna; Barstow, Joanna; Carone, Ludmila;
   Cegla, Heather; Domagal-Goldman, Shawn D.; Espinoza, Néstor; Giles,
   Helen; Gully-Santiago, Michael; Haywood, Raphaelle; Hu, Renyu; Jordan,
   Andres; Kreidberg, Laura; Line, Michael; Llama, Joe; López-Morales,
   Mercedes; Marley, Mark S.; de Wit, Julien
2018arXiv180308708A    Altcode:
  Transmission spectroscopy during planetary transits is expected to be a
  major source of information on the atmospheres of small (approximately
  Earth-sized) exoplanets in the next two decades. This technique,
  however, is intrinsically affected by stellar spectral contamination
  caused by the fact that stellar photo- and chromospheres are not
  perfectly homogeneous. Such stellar contamination will often reach or
  exceed the signal introduced by the planetary spectral features. Finding
  effective methods to correct stellar contamination -- or at least to
  quantify its possible range -- for the most important exoplanets is a
  necessary step for our understanding of exoplanet atmospheres. This
  will require significantly deepening our understanding of stellar
  heterogeneity, which is currently limited by the available data.

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Title: The Transit Light Source Effect: False Spectral Features and
    Incorrect Densities for M-dwarf Transiting Planets
Authors: Rackham, Benjamin V.; Apai, Dániel; Giampapa, Mark S.
2018ApJ...853..122R    Altcode: 2017arXiv171105691R
  Transmission spectra are differential measurements that utilize stellar
  illumination to probe transiting exoplanet atmospheres. Any spectral
  difference between the illuminating light source and the disk-integrated
  stellar spectrum due to starspots and faculae will be imprinted in the
  observed transmission spectrum. However, few constraints exist for the
  extent of photospheric heterogeneities in M dwarfs. Here we model spot
  and faculae covering fractions consistent with observed photometric
  variabilities for M dwarfs and the associated 0.3-5.5 μm stellar
  contamination spectra. We find that large ranges of spot and faculae
  covering fractions are consistent with observations and corrections
  assuming a linear relation between variability amplitude, and covering
  fractions generally underestimate the stellar contamination. Using
  realistic estimates for spot and faculae covering fractions, we
  find that stellar contamination can be more than 10× larger than
  the transit depth changes expected for atmospheric features in rocky
  exoplanets. We also find that stellar spectral contamination can lead to
  systematic errors in radius and therefore the derived density of small
  planets. In the case of the TRAPPIST-1 system, we show that TRAPPIST-1's
  rotational variability is consistent with spot covering fractions
  {f}<SUB>{spot</SUB>}={8}<SUB>-7</SUB><SUP>+18</SUP> % and faculae
  covering fractions {f}<SUB>{fac</SUB>}={54}<SUB>-46</SUB><SUP>+16</SUP>
  % . The associated stellar contamination signals alter the transit
  depths of the TRAPPIST-1 planets at wavelengths of interest for
  planetary atmospheric species by roughly 1-15× the strength of
  planetary features, significantly complicating JWST follow-up
  observations of this system. Similarly, we find that stellar
  contamination can lead to underestimates of the bulk densities of the
  TRAPPIST-1 planets of {{Δ }}(ρ )=-{8}<SUB>-20</SUB><SUP>+7</SUP> %
  , thus leading to overestimates of their volatile contents.

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Title: Exoplanet Transits of Stellar Active Regions
Authors: Giampapa, Mark S.; Andretta, Vincenzo; Covino, Elvira;
   Reiners, Ansgar; Esposito, Massimiliano
2018AAS...23123402G    Altcode:
  We report preliminary results of a program to obtain high spectral-
  and temporal-resolution observations of the neutral helium triplet
  line at 1083.0 nm in transiting exoplanet systems. The principal
  objective of our program is to gain insight on the properties of
  active regions, analogous to solar plages, on late-type dwarfs by
  essentially using exoplanet transits as high spatial resolution
  probes of the stellar surface within the transit chord. The 1083 nm
  helium line is a particularly appropriate diagnostic of magnetized
  areas since it is weak in the quiet photosphere of solar-type stars
  but appears strongly in absorption in active regions. Therefore,
  during an exoplanet transit over the stellar surface, variations in
  its absorption equivalent width can arise that are functions of the
  intrinsic strength of the feature in the active region and the known
  relative size of the exoplanet. We utilized the Galileo Telescope and
  the GIANO-B near-IR echelle spectrograph to obtain 1083 nm spectra
  during transits in bright, well-known systems that include HD 189733,
  HD 209458, and HD 147506 (HAT-P-2). We also obtained simultaneous
  auxiliary data on the same telescope with the HARPS-N UV-Visible
  echelle spectrograph. We will present preliminary results from our
  analysis of the observed variability of the strength of the He I
  1083 nm line during transits.Acknowledgements: Based on observations
  made with the Italian Telescopio Nazionale Galileo (TNG) operated on
  the island of La Palma by the Fundación Galileo Galilei of the INAF
  (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del
  Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The
  NSO is operated by AURA under a cooperative agreement with the NSF.

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Title: The Light Source Problem: The Effect of Heterogeneous Stellar
    Photospheres on Searches for Transiting Exoplanet Biosignatures
Authors: Rackham, B. V.; Apai, D.; Giampapa, M. S.
2017LPICo2042.4032R    Altcode:
  TESS will soon enable the study of terrestrial exoplanet
  atmospheres. However, spots and faculae in stellar photospheres can
  complicate these measurements by mimicking or masking atmospheric
  features. We detail our work to constrain this effect.

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Title: VizieR Online Data Catalog: HeI 5876 &amp; 10830Å EWs of
    solar-type stars (Andretta+, 2017)
Authors: Andretta, V.; Giampapa, M. S.; Covino, E.; Reiners, A.;
   Beeck, B.
2017yCat..18390097A    Altcode:
  A total of 134 FEROS spectra (R=48000) of our targets (including
  telluric standards) were acquired on the night of UT 2011 December
  6-7; spectral coverage from 3500 to 9200Å. The Fiber Extended-range
  Optical Spectrograph (FEROS) was mounted at the 2.2m Max-Planck
  Gesellschaft/European Southern Observatory (MPG/ESO) telescope at La
  Silla (Chile). <P />The HeIλ10830 spectroscopic observations were
  carried out on the same night as the FEROS D<SUB>3</SUB> observations,
  using the CRyogenic high-resolution InfraRed Echelle Spectrograph
  (CRIRES), mounted at Unit Telescope 1 (Antu) of the VLT array at Cerro
  Paranal. <P />The details of the observations is given in table 1. <P
  />(3 data files).

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Title: The Effect of Stellar Contamination on Transmission Spectra
    of Low-mass Exoplanets
Authors: Rackham, Benjamin V.; Apai, Daniel; Giampapa, Mark S.
2017DPS....4941620R    Altcode:
  Transmission spectroscopy offers the exciting possibility of studying
  terrestrial exoplanet atmospheres in the near-term future. The
  Transiting Exoplanet Survey Satellite (TESS), scheduled for launch
  next year, is expected to discover thousands of transiting exoplanets
  around bright host stars, including an estimated twenty habitable zone
  super-Earths. The brightness of the TESS host stars, combined with
  refined observational strategies and near-future facilities, will
  enable searches for atmospheric signatures from smaller and cooler
  exoplanets. These observations, however, will be increasingly subject
  to noise introduced by heterogeneities in the host star photospheres,
  such as star spots and faculae. In short, the transmission spectroscopy
  method relies on the assumption that the spectrum of the transit
  chord does not differ from that of the integrated stellar disk
  or, if it does, the contribution of photospheric heterogeneities
  to the transmission spectrum can be constrained by variability
  monitoring. However, any axisymmetric populations of spots and faculae
  will strongly affect transmission spectra, and their presence cannot be
  deduced from monitoring efforts. A clear need exists for a more robust
  understanding of stellar contamination on transmission spectra. Here we
  summarize our work on the impact of heterogeneous stellar photospheres
  on transmission spectra and detail implications for atmospheric
  characterization efforts. By modeling spot and faculae distributions
  in stellar photospheres, we find that spot-covering fractions
  extrapolated from observed variability amplitudes are significantly
  underestimated. Likewise, corrections based on variability monitoring
  likely fall short of the actual stellar spectral contamination. We
  provide examples of contamination spectra for typical levels of stellar
  activity across a range of spectral types. For M dwarfs, molecular
  absorption features in spots and faculae can imprint apparent features
  in transmission spectra of small exoplanets, including those of the
  TRAPPIST-1 system. Constraining stellar contamination will likely be
  a limiting factor for detecting atmospheric features in transmission
  spectra of low-mass exoplanets around late-type stars from TESS.

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Title: Science-Driven Optimization of the LSST Observing Strategy
Authors: LSST Science Collaboration; Marshall, Phil; Anguita, Timo;
   Bianco, Federica B.; Bellm, Eric C.; Brandt, Niel; Clarkson, Will;
   Connolly, Andy; Gawiser, Eric; Ivezic, Zeljko; Jones, Lynne; Lochner,
   Michelle; Lund, Michael B.; Mahabal, Ashish; Nidever, David; Olsen,
   Knut; Ridgway, Stephen; Rhodes, Jason; Shemmer, Ohad; Trilling, David;
   Vivas, Kathy; Walkowicz, Lucianne; Willman, Beth; Yoachim, Peter;
   Anderson, Scott; Antilogus, Pierre; Angus, Ruth; Arcavi, Iair; Awan,
   Humna; Biswas, Rahul; Bell, Keaton J.; Bennett, David; Britt, Chris;
   Buzasi, Derek; Casetti-Dinescu, Dana I.; Chomiuk, Laura; Claver, Chuck;
   Cook, Kem; Davenport, James; Debattista, Victor; Digel, Seth; Doctor,
   Zoheyr; Firth, R. E.; Foley, Ryan; Fong, Wen-fai; Galbany, Lluis;
   Giampapa, Mark; Gizis, John E.; Graham, Melissa L.; Grillmair, Carl;
   Gris, Phillipe; Haiman, Zoltan; Hartigan, Patrick; Hawley, Suzanne;
   Hlozek, Renee; Jha, Saurabh W.; Johns-Krull, C.; Kanbur, Shashi;
   Kalogera, Vassiliki; Kashyap, Vinay; Kasliwal, Vishal; Kessler,
   Richard; Kim, Alex; Kurczynski, Peter; Lahav, Ofer; Liu, Michael C.;
   Malz, Alex; Margutti, Raffaella; Matheson, Tom; McEwen, Jason D.;
   McGehee, Peregrine; Meibom, Soren; Meyers, Josh; Monet, Dave; Neilsen,
   Eric; Newman, Jeffrey; O'Dowd, Matt; Peiris, Hiranya V.; Penny, Matthew
   T.; Peters, Christina; Poleski, Radoslaw; Ponder, Kara; Richards,
   Gordon; Rho, Jeonghee; Rubin, David; Schmidt, Samuel; Schuhmann,
   Robert L.; Shporer, Avi; Slater, Colin; Smith, Nathan; Soares-Santos,
   Marcelles; Stassun, Keivan; Strader, Jay; Strauss, Michael; Street,
   Rachel; Stubbs, Christopher; Sullivan, Mark; Szkody, Paula; Trimble,
   Virginia; Tyson, Tony; de Val-Borro, Miguel; Valenti, Stefano; Wagoner,
   Robert; Wood-Vasey, W. Michael; Zauderer, Bevin Ashley
2017arXiv170804058L    Altcode:
  The Large Synoptic Survey Telescope is designed to provide an
  unprecedented optical imaging dataset that will support investigations
  of our Solar System, Galaxy and Universe, across half the sky and
  over ten years of repeated observation. However, exactly how the LSST
  observations will be taken (the observing strategy or "cadence")
  is not yet finalized. In this dynamically-evolving community white
  paper, we explore how the detailed performance of the anticipated
  science investigations is expected to depend on small changes to
  the LSST observing strategy. Using realistic simulations of the LSST
  schedule and observation properties, we design and compute diagnostic
  metrics and Figures of Merit that provide quantitative evaluations of
  different observing strategies, analyzing their impact on a wide range
  of proposed science projects. This is work in progress: we are using
  this white paper to communicate to each other the relative merits
  of the observing strategy choices that could be made, in an effort
  to maximize the scientific value of the survey. The investigation of
  some science cases leads to suggestions for new strategies that could
  be simulated and potentially adopted. Notably, we find motivation for
  exploring departures from a spatially uniform annual tiling of the sky:
  focusing instead on different parts of the survey area in different
  years in a "rolling cadence" is likely to have significant benefits
  for a number of time domain and moving object astronomy projects. The
  communal assembly of a suite of quantified and homogeneously coded
  metrics is the vital first step towards an automated, systematic,
  science-based assessment of any given cadence simulation, that will
  enable the scheduling of the LSST to be as well-informed as possible.

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Title: Estimates of Active Region Area Coverage through Simultaneous
    Measurements of the He I λλ 5876 and 10830 Lines
Authors: Andretta, Vincenzo; Giampapa, Mark S.; Covino, Elvira;
   Reiners, Ansgar; Beeck, Benjamin
2017ApJ...839...97A    Altcode: 2017arXiv170310060A
  Simultaneous, high-quality measurements of the neutral helium triplet
  features at 5876 Å and 10830 Å in a sample of solar-type stars are
  presented. The observations were made with ESO telescopes at the La
  Silla Paranal Observatory under program ID 088.D-0028(A) and MPG Utility
  Run for Fiber Extended-range Optical Spectrograph 088.A-9029(A). The
  equivalent widths of these features combined with chromospheric models
  are utilized to infer the fractional area coverage, or filling factor,
  of magnetic regions outside of spots. We find that the majority of the
  sample is characterized by filling factors less than unity. However,
  discrepancies occur among the coolest K-type and the warmest and
  most rapidly rotating F-type dwarf stars. We discuss these apparently
  anomalous results and find that in the case of K-type stars, they are
  an artifact of the application of chromospheric models best suited to
  the Sun than to stars with significantly lower T <SUB>eff</SUB>. The
  case of the F-type rapid rotators can be explained by the measurement
  uncertainties of the equivalent widths, but they may also be due
  to a non-magnetic heating component in their atmospheres. With the
  exceptions noted above, preliminary results suggest that the average
  heating rates in the active regions are the same from one star to
  the other, differing in the spatially integrated, observed level of
  activity due to the area coverage. Hence, differences in activity in
  this sample are mainly due to the filling factor of active regions.

---------------------------------------------------------
Title: The Photometric Variability of Solar-Type Stars
Authors: Giampapa, Mark S.
2016IAUFM..29A.365G    Altcode:
  The joint variability of chromospheric emission with the integrated
  flux in the Kepler visible band for the Sun as a star is examined. No
  correlation between our Ca II K line parameter and the Kepler passband
  is seen, suggesting that visible-band variability in solar-like stars
  is mostly independent of solar-like chromospheric activity. However,
  the K-line parameter time series and the total solar flux in the
  infrared K band appear weakly correlated, reflecting the wavelength
  dependence of the relationship between magnetic activity and broadband
  variability. We then apply a schematic, three-component model as a
  framework for the discussion of stellar photometric variability as
  observed by Kepler. The model confirms that spots tend to dominate
  stellar photometric variability in the visible though interesting
  cases do emerge where the facular disk coverage may become important
  in determining the amplitude of broadband variability.

---------------------------------------------------------
Title: Maximizing Science in the Era of LSST: A Community-Based
    Study of Needed US Capabilities
Authors: Najita, Joan; Willman, Beth; Finkbeiner, Douglas P.; Foley,
   Ryan J.; Hawley, Suzanne; Newman, Jeffrey A.; Rudnick, Gregory; Simon,
   Joshua D.; Trilling, David; Street, Rachel; Bolton, Adam; Angus, Ruth;
   Bell, Eric F.; Buzasi, Derek; Ciardi, David; Davenport, James R. A.;
   Dawson, Will; Dickinson, Mark; Drlica-Wagner, Alex; Elias, Jay; Erb,
   Dawn; Feaga, Lori; Fong, Wen-fai; Gawiser, Eric; Giampapa, Mark;
   Guhathakurta, Puragra; Hoffman, Jennifer L.; Hsieh, Henry; Jennings,
   Elise; Johnston, Kathryn V.; Kashyap, Vinay; Li, Ting S.; Linder,
   Eric; Mandelbaum, Rachel; Marshall, Phil; Matheson, Thomas; Meibom,
   Soren; Miller, Bryan W.; O'Meara, John; Reddy, Vishnu; Ridgway, Steve;
   Rockosi, Constance M.; Sand, David J.; Schafer, Chad; Schmidt, Sam;
   Sesar, Branimir; Sheppard, Scott S.; Thomas, Cristina A.; Tollerud,
   Erik J.; Trump, Jon; von der Linden, Anja
2016arXiv161001661N    Altcode:
  The Large Synoptic Survey Telescope (LSST) will be a discovery machine
  for the astronomy and physics communities, revealing astrophysical
  phenomena from the Solar System to the outer reaches of the observable
  Universe. While many discoveries will be made using LSST data alone,
  taking full scientific advantage of LSST will require ground-based
  optical-infrared (OIR) supporting capabilities, e.g., observing
  time on telescopes, instrumentation, computing resources, and
  other infrastructure. This community-based study identifies, from a
  science-driven perspective, capabilities that are needed to maximize
  LSST science. Expanding on the initial steps taken in the 2015 OIR
  System Report, the study takes a detailed, quantitative look at the
  capabilities needed to accomplish six representative LSST-enabled
  science programs that connect closely with scientific priorities from
  the 2010 decadal surveys. The study prioritizes the resources needed
  to accomplish the science programs and highlights ways that existing,
  planned, and future resources could be positioned to accomplish the
  science goals.

---------------------------------------------------------
Title: Maximizing Science in the Era of LSST, Stars Study Group
Report: Rotation and Magnetic Activity in the Galactic Field
    Population and in Open Star Clusters
Authors: Hawley, Suzanne L.; Angus, Ruth; Buzasi, Derek; Davenport,
   James R. A.; Giampapa, Mark; Kashyap, Vinay; Meibom, Soren
2016arXiv160704302H    Altcode:
  This is the stars chapter of the Kavli workshop report, which resulted
  from the community-based study of needed US OIR capabilities in
  the LSST era. The full report, which will include this chapter,
  is anticipated to be available in Fall 2016. See NOAO website
  (http://www.noao.edu/meetings/lsst-oir-study/) for more details.

---------------------------------------------------------
Title: The solar-stellar connection
Authors: Giampapa, Mark S.
2016AsJPh..25..411G    Altcode:
  A review of some principal results achieved in the area of stellar
  astrophysics with its origins in solar physics - the Solar-Stellar
  Connection - is presented from the perspective of an observational
  astronomer. The historical origins of the Solar-Stellar Connection
  are discussed followed by a review of key results from observations
  of stellar cycles analogous to the solar cycle in terms of parameters
  relevant to dynamo theory. A review of facets of angular momentum
  evolution and irradiance variations, each of which is determined
  by emergent, dynamo-generated magnetic fields, is given. Recent
  considerations of the impacts of stellar magnetic activity on the
  ambient radiative and energetic particle environment of the habitable
  zone of exoplanet systems are summarized. Some anticipated directions
  of the Solar-Stellar Connection in the new era of astronomy as defined
  by the advent of transformative facilities are presented.

---------------------------------------------------------
Title: Variability of Kepler Solar-like Stars Harboring Small
    Exoplanets
Authors: Howell, Steve B.; Ciardi, David R.; Giampapa, Mark S.;
   Everett, Mark E.; Silva, David R.; Szkody, Paula
2016AJ....151...43H    Altcode: 2015arXiv151203108H
  We examine Kepler light-curve variability on habitable zone transit
  timescales for a large uniform sample of spectroscopically studied
  Kepler exoplanet host stars. The stars, taken from Everett et al.,
  are solar-like in their properties and each harbors at least one
  exoplanet (or candidate) of radius ≤2.5 {R}<SUB>{{e</SUB>}}. The
  variability timescale examined is typical for habitable zone planets
  orbiting solar-like stars and we note that the discovery of the
  smallest exoplanets (≤1.2 {R}<SUB>{{e</SUB>}}) with corresponding
  transit depths of less than ∼0.18 mmag occur for the brightest and
  photometrically quietest stars. Thus, these detections are quite rare in
  Kepler observations. Some brighter and more evolved stars (subgiants),
  the latter of which often show large radial velocity jitter, are found
  to be among the photometrically quietest solar-like stars in our sample
  and the most likely small planet transit hunting grounds. The Sun is
  discussed as a solar-like star proxy to provide insight into the nature
  and cause of photometric variability. It is shown that Kepler’s broad,
  visible light observations are insensitive to variability caused by
  chromospheric activity that may be present in the observed stars.

---------------------------------------------------------
Title: Photometric Variations In The Sun And Solar-Type Stars
Authors: Giampapa, Mark
2016csss.confE...1G    Altcode:
  The rich array of solar magnetic field-related phenomena we see occurs
  not only on stellar counterparts of our Sun but in stars that represent
  significant departures in their fundamental parameters from those of
  the<BR /> Sun. Though these phenomena appear energetically negligible
  when compared to the total luminosity of stars, they nevertheless
  govern the angular momentum evolution and modulate the radiative
  and particle output of the Sun and late-type stars. The term "The
  Solar-Stellar Connection" has been coined to describe the solar-stellar
  synergisms in the investigation of the generation, emergence and
  coupling of magnetic fields with the outer solar-stellar atmosphere
  to produce what we broadly refer to as magnetic activity. With the
  discovery of literally thousands of planets beyond our solar system,
  the Solar-Stellar-Planet Connection is quickly emerging as a new area
  of investigation of the impacts of magnetic activity on exoplanet
  atmospheres. In parallel with this rapid evolution in our perspectives
  is the advent of transformative facilities for the study of the Sun and
  the dynamic Universe. The primary focus of this invited talk will be on
  photometric variations in solar-type stars and the Sun. These brightness
  variations are associated with thermal homogeneities typically defined
  by magnetic structures that are also spatially coincident with key
  radiative proxies. Photometric variability in solar-type stars and the
  Sun includes transient brightening, rotational modulation by cool spots
  and cycle-related variability, each with a characteristic signature in
  time and wavelength. The emphasis<BR /> of this presentation will be on
  the relationship between broadband photometric variations and magnetic
  field-related activity in solar-type stars and the Sun. Facets of this
  topic will be discussed both retrospectively and prospectively as we
  enter a revolutionary, new era for astronomy.

---------------------------------------------------------
Title: Seeing SPOTS with SOFIA: Starspot Photometric Observations
    of Transiting Systems
Authors: Giampapa, Mark
2015sofi.prop...24G    Altcode:
  We propose to utilize the unique capabilities provided by HIPO/FLITECAM
  (FLIPO) and the FPI to obtain simultaneous, time-resolved multi-color
  photometry extending from the visible to the near infrared of
  magnetically active dwarf stars that are also the hosts of transiting
  exoplanets. In this way, we can measure the fundamental properties of
  starspots that are eclipsed by the transiting planet and thereby provide
  much improved constraints for starspot models than has been possible
  with the single-band data from Kepler and CoRoT. Since starspots are
  the strongest concentrations of magnetic flux on the Sun and stars, an
  understanding of their properties can yield critical constraints for
  stellar dynamo models and influence our views of the role of stellar
  magnetic activity in star-planet interactions.

---------------------------------------------------------
Title: A Method for Measuring Active Region Filling Factors on
    Solar-Type Stars
Authors: Giampapa, Mark Steven; Andretta, Vincenzo; Beeck, Benjamin;
   Reiners, Ansgar; Schussler, Manfred
2015TESS....120101G    Altcode:
  Radiative diagnostics of “activity” in the Sun and solar-type stars
  are spatially associated with sites of emergent magnetic flux. The
  magnetic fields themselves are widely regarded as the surface
  manifestations of a dynamo mechanism. The further development of
  both dynamo theory and models of the non-radiative heating of outer
  stellar atmospheres requires a knowledge of stellar magnetic field
  properties. In this context, it becomes important to determine the
  surface distribution, or at least the fractional coverage of, magnetic
  active regions as one critical constraint for dynamo models. But,
  while information on the spatial distribution of activity on stellar
  surfaces can be gathered in some special cases (mostly rapid rotators),
  such measurements have always been elusive in more solar-like stars. We
  discuss the challenges and results obtained from a method that relies
  on the non-linear response of the two principal He I triplet lines
  (at 1083 nm and 587.6 nm) to infer useful constraints on the fractional
  area coverage of magnetic active regions on solar-type stars.

---------------------------------------------------------
Title: SOLIS: Reconciling Disk-integrated and Disk-resolved Spectra
    from the Sun
Authors: Pevtsov, Alexei A.; Bertello, Luca; Harker, Brian; Giampapa,
   Mark; Marble, Andrew R.
2015csss...18..887P    Altcode: 2014arXiv1411.7266P
  Unlike other stars, the surface of the Sun can be spatially resolved
  to a high degree of detail . But the Sun can also be observed as if
  it was a distant star. The availability of solar disk-resolved and
  disk-integrated spectra offers an opportunity to devise methods to
  derive information about the spatial distribution of solar features
  from Sun-as-a-star measurements. Here, we present an update on work
  done at the National Solar Observatory to reconcile disk-integrated
  and disk-resolved solar spectra from the Synoptic Optical Long-term
  Investigation of the Sun (SOLIS) station. The results of this work
  will lead to a new approach to infer the information about the spatial
  distribution of features on other stars, from the overall filling factor
  of active regions to, possibly, the latitude/longitude distribution
  of features.

---------------------------------------------------------
Title: Line Bisector Variability in the Sun as a Star
Authors: Giampapa, Mark; Bertello, Luca
2015csss...18..495G    Altcode:
  We utilize spectra obtained with the Integrated Sunlight Spectrometer
  (ISS) instrument of the NSO SOLIS facility on Kitt Peak, AZ to perform
  a preliminary study of the variability of line asymmetries in the Mn I
  line at 539.5 nm and the nearby Fe I line at 539.3 nm, respectively. We
  derive the line bisector for these photospheric features from
  daily spectra of the Sun as a star acquired since January 2007, and
  characterize the variability of a measure of bisector amplitude with
  the solar cycle. A simple two-component model of the solar magnetic
  field is investigated as a possible origin for the variation in line
  depth with time of the magnetically sensitive Mn I feature.

---------------------------------------------------------
Title: Solar Cycle Dependency of Sun-as-a-Star Photospheric Spectral
    Line Profiles
Authors: Bertello, Luca; Pevtsov, Alexei A.; Giampapa, Mark S.;
   Marble, Andrew R.
2015csss...18..693B    Altcode:
  We investigate solar-cycle related changes in the profile of several
  photospheric spectral lines taken with the Integrated Sunlight
  Spectrometer (ISS) operating at the National Solar Observatory at Kitt
  Peak (Arizona). ISS, which is one of three instruments comprising
  the Synoptic Optical Long-term Investigations of the Sun (SOLIS)
  facility, is designed to obtain high spectral resolution (R = 300,000)
  observations of the Sun-as-a-star in a broad range of wavelengths
  (350 nm - 1100 nm). Daily measurements were obtained since December
  2006, covering the decline of solar cycle 23 and the rising phase of
  cycle 24. We present time series of line parameters and discuss their
  correlation to indices of solar magnetic activity. Because of their
  different response to variations in the thermodynamic and magnetic
  structures of the solar atmosphere, the measured line shape parameters
  provide an excellent tool for disentangling thermal and magnetic effects
  occurring during different phases of the solar cycle. The results of
  this analysis may also help with developing a better understanding of
  magnetic cycles of activity in other solar-like stars.

---------------------------------------------------------
Title: Stellar Activity and Variability: Our Sun in a Stellar Context
Authors: Giampapa, M.
2013ASPC..478..365G    Altcode:
  The variability of the Sun in its chromospheric emission and associated
  irradiance changes is compared with that of other solar-type stars. A
  review of the results thus far obtained indicates that the Sun is not
  atypical in its magnetic field-related variations when compared to
  relatively homogeneous samples of stars that are also solar-like in
  key parameters such as effective temperature, gravity, rotation rate,
  and mean level of activity. In a comparison with more heterogeneous
  samples of ostensibly solar-type stars, the Sun appears to reside
  at a boundary between “active” and “quiet” chromosphere
  stars, suggesting that the structure of the outer solar atmosphere as
  delineated by emergent magnetic fields includes attributes of each of
  these broad stellar categories.

---------------------------------------------------------
Title: Stellar cycles: general properties and future directions
Authors: Giampapa, Mark S.
2012IAUS..286..257G    Altcode:
  We discuss the general properties of stellar cycles with emphasis on
  their amplitudes as a function of stellar parameters, particularly
  those stellar characteristics relevant to dynamo-driven magnetic
  activity. We deduce an empirical scaling relation between cycle
  frequency and differential rotation based on previously established
  empirical relations. We also compare the recent Cycle 23 to cycles
  in solar-type stars. We find that the extended minimum of Cycle 23
  resembled in its Ca II H &amp; K emission at minimum the mean levels
  of activity seen in stars with no cycles.

---------------------------------------------------------
Title: Joint Response of the Helium Lines to Chromospheric Heating
    in Solar-type Stars
Authors: Giampapa, Mark S.; Andretta, V.; Beeck, B.; Reiners, A.;
   Schussler, M.
2012AAS...22020314G    Altcode:
  We present a preliminary report on simultaneous observations of
  the He I 5876 and 10830 triplet lines, respectively, in a sample of
  solar-type stars. The near-IR spectra were obtained with the VLT and
  CRIRES instrument while the visible spectra were acquired with the
  MPG/ESO 2.2-m telescope in conjunction with the FEROS spectrograph. The
  correlation of the observed strengths of these lines will be examined
  and their potential as diagnostics of active region area coverage in
  solar-type stars will be discussed. <P />The NSO is operated by AURA
  under a cooperative agreement with the National Science Foundation.

---------------------------------------------------------
Title: Estimating the Fractional Area Coverage of Active Regions in
    Dwarf Stars
Authors: Andretta, V.; Giampapa, M.
2011ASPC..448.1111A    Altcode: 2011csss...16.1111A
  It has been shown (Andretta &amp; Giampapa 1995) that the two He I
  triplet lines at 1.083 μm and 587.6 nm, respectively, can be utilized
  to infer the area coverage of active (plage-like) regions on stellar
  surfaces by exploiting their different responses to chromospheric
  heating. This kind of information, which is very difficult to obtain
  through other methods, can serve as a fundamental constraint for
  the development of stellar dynamo theory. We discuss the application
  and limitations of this approach to the interpretation of spatially
  resolved solar data along with some preliminary stellar observations.

---------------------------------------------------------
Title: Splinter Session "Solar and Stellar Flares"
Authors: Fletcher, L.; Hudson, H.; Cauzzi, G.; Getman, K. V.; Giampapa,
   M.; Hawley, S. L.; Heinzel, P.; Johnstone, C.; Kowalski, A. F.; Osten,
   R. A.; Pye, J.
2011ASPC..448..441F    Altcode: 2011csss...16..441F; 2012arXiv1206.3997F
  This summary reports on papers presented at the Cool Stars-16 meeting in
  the splinter session "Solar and Stellar flares." Although many topics
  were discussed, the main themes were the commonality of interests,
  and of physics, between the solar and stellar flare communities,
  and the opportunities for important new observations in the near future.

---------------------------------------------------------
Title: The evolution of stellar surface activity and possible effects
    on exoplanets
Authors: Giampapa, Mark S.
2011IAUS..273...68G    Altcode:
  The evolution of stellar activity involves a complex interplay
  between the interior dynamo mechanism, the emergent magnetic field
  configurations and their coupling with stellar winds, the subsequent
  angular momentum evolution, and fundamental stellar parameters. The
  discussion of the evolution of surface activity will emphasize the
  main sequence phase, from the ZAMS to stars of solar-age. We will
  focus particularly on the evolution of the fractional area coverages
  of spots on the surfaces of solar-type stars. We fit an empirical
  relation to the fractional mean spot area coverage as a function of age
  for ages greater than the Pleiades of the form log(MeanSpotCoverage) =
  0.90(+/-0.26) - 1.03(+/-0.10)log(Age), where Age is in Myr. In addition,
  we summarize the relative evolution of radiative emissions in various
  short wavelength bands that are associated with stellar magnetic
  field-related activity. Possible effects on young planetary atmospheres
  also are appropriate to consider given that stellar surface activity
  is the origin of the high-energy component of the ambient radiation
  and particle fields in which planetary atmosphere evolution occurs.

---------------------------------------------------------
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: Photometric Variability of Solar-Type Stars in the Young
    Pleiades Open Cluster
Authors: Giampapa, Mark S.; Sherry, W. H.; Craine, E. R.
2010AAS...21640014G    Altcode: 2010BAAS...41..856G
  We present some preliminary results from a program of intensive
  photometric monitoring of four solar-type stars in the young Pleiades
  cluster at an age of approximately 100 Myr utilizing a small-aperture
  robotic telescope. The Pleiades targets and their spectral types
  include hz 212 (K7), hz 253 (G1 V), hz 345 (G8 V) and hz 489 (G0
  V). Photometry of the comparison stars and selected field stars included
  in the CCD frame is also given. The monitoring program over 43 nights
  of observations and 1500 frames yields information on the nature of
  both long-term variability and any short-term, transient activity
  such as flare outbursts. <P />This investigation is part of a broad
  effort to delineate the joint evolution of activity and irradiance
  variability in solar-type stars that may be the hosts of planetary
  systems. Understanding the nature of the joint variability of irradiance
  and magnetic activity on sun-like stars spanning a range of ages will
  provide crucial insight on how frequently earth-like atmospheres are
  likely to form and survive, and how frequently exo-earths encounter
  benign climatic variations. <P />We acknowledge support by a grant from
  the NASA Astrobiology Institute. The NSO and the NOAO are each operated
  by AURA under separate cooperative agreements with the National Science
  Foundation. <P />This research was partially supported by a grant from
  the American Astronomical Association.

---------------------------------------------------------
Title: The Asteroseismic Potential of Kepler: First Results for
    Solar-Type Stars
Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García,
   R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz,
   J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.;
   Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki,
   W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.;
   Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt,
   H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan,
   G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.;
   Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe,
   R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic,
   M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.;
   Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.;
   Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.;
   Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi,
   D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.;
   Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.;
   Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss,
   L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev,
   A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.;
   Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes,
   R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.;
   Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre,
   V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.;
   Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A.
2010ApJ...713L.169C    Altcode: 2010arXiv1001.0506C
  We present preliminary asteroseismic results from Kepler on three G-type
  stars. The observations, made at one-minute cadence during the first
  33.5 days of science operations, reveal high signal-to-noise solar-like
  oscillation spectra in all three stars: about 20 modes of oscillation
  may be clearly distinguished in each star. We discuss the appearance of
  the oscillation spectra, use the frequencies and frequency separations
  to provide first results on the radii, masses, and ages of the stars,
  and comment in the light of these results on prospects for inference
  on other solar-type stars that Kepler will observe.

---------------------------------------------------------
Title: Simultaneous Multi-Wavelength Observations of Magnetic Activity
    in Ultracool Dwarfs. III. X-ray, Radio, and Hα Activity Trends in
    M and L dwarfs
Authors: Berger, E.; Basri, G.; Fleming, T. A.; Giampapa, M. S.;
   Gizis, J. E.; Liebert, J.; Martín, E.; Phan-Bao, N.; Rutledge, R. E.
2010ApJ...709..332B    Altcode: 2009arXiv0909.4783B
  As part of our on-going investigation into the magnetic field
  properties of ultracool dwarfs, we present simultaneous radio, X-ray,
  and Hα observations of three M9.5-L2.5 dwarfs (BRI 0021-0214, LSR
  060230.4+391059, and 2MASS J052338.2-140302). We do not detect X-ray
  or radio emission from any of the three sources, despite previous
  detections of radio emission from BRI 0021 and 2M0523-14. Steady
  and variable Hα emission are detected from 2M0523-14 and BRI
  0021, respectively, while no Hα emission is detected from LSR
  0602+39. Overall, our survey of nine M8-L5 dwarfs doubles the number
  of ultracool dwarfs observed in X-rays, and triples the number of
  L dwarfs, providing in addition the deepest limits to date, log(L
  <SUB>X</SUB>/L <SUB>bol</SUB>) lsim -5. With this larger sample we find
  the first clear evidence for a substantial reduction in X-ray activity,
  by about two orders of magnitude, from mid-M to mid-L dwarfs. We
  find that the decline in Hα roughly follows L <SUB>Hα</SUB>/L
  <SUB>bol</SUB> vprop 10<SUP>-0.4×(SP-6)</SUP> for SP &gt;= 6, where SP
  = 0 for spectral type M0. In the radio band, however, the luminosity
  remains relatively unchanged from M0 to L4, leading to a substantial
  increase in L <SUB>rad</SUB>/L <SUB>bol</SUB>. Our survey also
  provides the first comprehensive set of simultaneous radio/X-ray/Hα
  observations of ultracool dwarfs, and reveals a clear breakdown of the
  radio/X-ray correlation beyond spectral type M7, evolving smoothly
  from L <SUB>ν,rad</SUB>/L <SUB>X</SUB> ≈ 10<SUP>-15.5</SUP> to
  ~10<SUP>-11.5</SUP> Hz<SUP>-1</SUP> over the narrow spectral-type range
  M7-M9. This breakdown reflects the substantial reduction in X-ray
  activity beyond M7, but its physical origin remains unclear since,
  as evidenced by the uniform radio emission, there is no drop in the
  field dissipation and particle acceleration efficiency. Based on the
  results of our survey, we conclude that a further investigation of
  magnetic activity in ultracool dwarfs will benefit from a two-pronged
  approach: multi-rotation observations of nearby known active sources
  and a snapshot survey of a large sample within ~50 pc to uncover rare
  flaring objects.

---------------------------------------------------------
Title: The Origin of Enhanced Activity in the Suns of M67
Authors: Reiners, A.; Giampapa, M. S.
2009ApJ...707..852R    Altcode: 2009arXiv0911.0424R
  We report the results of the analysis of high-resolution photospheric
  line spectra obtained with the UVES instrument on the VLT for a sample
  of 15 solar-type stars selected from a recent survey of the distribution
  of H and K chromospheric line strengths in the solar-age open cluster
  M67. We find upper limits to the projected rotation velocities that
  are consistent with solar-like rotation (i.e., v sin ilsim 2-3 km
  s<SUP>-1</SUP>) for objects with Ca II chromospheric activity within
  the range of the contemporary solar cycle. Two solar-type stars in
  our sample exhibit chromospheric emission well in excess of even
  solar maximum values. In one case, Sanders 1452, we measure a minimum
  rotational velocity of v sin i = 4 ± 0.5 km s<SUP>-1</SUP>, or over
  twice the solar equatorial rotational velocity. The other star with
  enhanced activity, Sanders 747, is a spectroscopic binary. We conclude
  that high activity in solar-type stars in M67 that exceeds solar
  levels is likely due to more rapid rotation rather than an excursion
  in solar-like activity cycles to unusually high levels. We estimate
  an upper limit of 0.2% for the range of brightness changes occurring
  as a result of chromospheric activity in solar-type stars and, by
  inference, in the Sun itself. We discuss possible implications for
  our understanding of angular momentum evolution in solar-type stars,
  and we tentatively attribute the rapid rotation in Sanders 1452 to a
  reduced braking efficiency.

---------------------------------------------------------
Title: Periodic Radio and Hα Emission from the L Dwarf Binary 2MASSW
J0746425+200032: Exploring the Magnetic Field Topology and Radius
    Of An L Dwarf
Authors: Berger, E.; Rutledge, R. E.; Phan-Bao, N.; Basri, G.;
   Giampapa, M. S.; Gizis, J. E.; Liebert, J.; Martín, E.; Fleming, T. A.
2009ApJ...695..310B    Altcode: 2008arXiv0809.0001B
  We present an 8.5 hr simultaneous radio, X-ray, UV, and optical
  observation of the L dwarf binary 2MASSW J0746425+200032. We detect
  strong radio emission, dominated by short-duration periodic pulses
  at 4.86 GHz with P = 124.32 ± 0.11 min. The stability of the pulse
  profiles and arrival times demonstrates that they are due to the
  rotational modulation of a B ≈ 1.7 kG magnetic field. A quiescent
  nonvariable component is also detected, likely due to emission from
  a uniform large-scale field. The Hα emission exhibits identical
  periodicity, but unlike the radio pulses it varies sinusoidally
  and is offset by exactly 1/4 of a phase. The sinusoidal variations
  require chromospheric emission from a large-scale field structure,
  with the radio pulses likely emanating from the magnetic poles. While
  both light curves can be explained by a rotating misaligned magnetic
  field, the 1/4 phase lag rules out a symmetric dipole topology since it
  would result in a phase lag of 1/2 (poloidal field) or zero (toroidal
  field). We therefore conclude that either (1) the field is dominated
  by a quadrupole configuration, which can naturally explain the 1/4
  phase lag; or (2) the Hα and/or radio emission regions are not
  trivially aligned with the field. Regardless of the field topology,
  we use the measured period along with the known rotation velocity (v
  sin i ≈ 27 km s<SUP>-1</SUP>), and the binary orbital inclination
  (i ≈ 142°), to derive a radius for the primary star of 0.078 ±
  0.010 R <SUB>sun</SUB>. This is the first measurement of the radius of
  an L dwarf, and along with a mass of 0.085 ± 0.010 M <SUB>sun</SUB>
  it provides a constraint on the mass-radius relation below 0.1 M
  <SUB>sun</SUB>. We find that the radius is about 30% smaller than
  expected from theoretical models, even for an age of a few Gyr. The
  origin of this discrepancy is either a breakdown of the models at the
  bottom of the main sequence, or a significant misalignment between
  the rotational and orbital axes.

---------------------------------------------------------
Title: Photometric variability of solar-type members of the Pleiades
    open cluster
Authors: Giampapa, Mark; Sherry, William; Craine, Eric; Tucker, Roy
2009AIPC.1094..648G    Altcode: 2009csss...15..648G
  We present some preliminary results from a program utilizing a
  small-aperture transit telescope for the photometric monitoring of
  a set of solar-type stars in the young Pleiades cluster at an age of
  approximately 100 Myr. The photometry sample includes 12 stars in the
  (B-V)<SUB>0</SUB> color range of 0.58-0.76, corresponding to a range
  in spectral type of approximately F9 V-G9 V.

---------------------------------------------------------
Title: The Lifetime of Magnetic Fields in Fully Convective Brown
    Dwarfs
Authors: Berger, Edo; Giampapa, Mark; Sherry, William
2009noao.prop...84B    Altcode:
  Until recently theoretical expectation was that magnetic activity would
  disappear in fully convective ultracool dwarfs (very low mass stars
  and brown dwarfs). We now know that magnetic activity in fact exists,
  but the origin, configuration, and lifetime of the field and dynamo
  remain largely unconstrained. Numerical simulations cannot presently
  accommodate the relevant conditions in the lowest mass objects, and
  progress mainly relies on observational clues. Recently, we uncovered
  the first examples of periodic and sinusoidal H(alpha) emission from two
  ultracool dwarfs (with a period of 2 hours). The H(alpha) emission is
  due to a large-scale magnetic hot spot that rigidly rotates with the
  stars. Here we propose observations separated by 1 and 2 years from
  the original discovery in order to assess the stability timescale of
  the magnetic field, a crucial constraint on the nature of the dynamo
  mechanism.

---------------------------------------------------------
Title: The Stars as a Sun: Secular Variations of Cycling and
    Non-Cycling Stars
Authors: Hall, Jeffrey C.; Giampapa, Mark S.; Henry, Gregory W.;
   Lean, Judith L.; Saar, Steven H.; Soderblom, David R.
2009astro2010S.111H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Causes of Solar Activity
Authors: Giampapa, Mark S.; Gibson, Sarah; Harvey, J. W.; Hill, Frank;
   Norton, Aimee A.; Pevtsov, A.
2009astro2010S..92G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Asteroseismology: The Next Frontier in Stellar Astrophysics
Authors: Giampapa, Mark S.; Aerts, Conny; Bedding, Tim; Bonanno,
   Alfio; Brown, Timothy M.; Christensen-Dalsgaard, Jorgen; Dominik,
   Martin; Ge, Jian; Gilliland, Ronald L.; Harvey, J. W.; Hill, Frank;
   Kawaler, Steven D.; Kjeldsen, Hans; Kurtz, D. W.; Marcy, Geoffrey W.;
   Matthews, Jaymie M.; Monteiro, Mario Joao P. F. G.; Schou, Jesper
2009astro2010S..91G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A global SOLIS vector spectromagnetograph (VSM) network
Authors: Streander, K. V.; Giampapa, M. S.; Harvey, J. W.; Henney,
   C. J.; Norton, A. A.
2008SPIE.7014E..7PS    Altcode: 2008SPIE.7014E.251S
  Understanding the Sun's magnetic field related activity is far
  from complete as reflected in the limited ability to make accurate
  predictions of solar variability. To advance our understanding of solar
  magnetism, the National Solar Observatory (NSO) constructed the Synoptic
  Optical Long-term Investigations of the Sun (SOLIS) suite of instruments
  to conduct high precision optical measurements of processes on the Sun
  whose study requires sustained observations over long time periods. The
  Vector Spectromagnetograph (VSM), the principal SOLIS instrument,
  has been in operation since 2003 and obtains photospheric vector data,
  as well as photospheric and chromospheric longitudinal magnetic field
  measurements. Instrument performance is being enhanced by employing
  new, high-speed cameras that virtually freeze seeing, thus improving
  sensitivity to measure the solar magnetic field configuration. A major
  operational goal is to provide real-time and near-real-time data for
  forecasting space weather and increase scientific yield from shorter
  duration solar space missions and ground-based research projects. The
  National Solar Observatory proposes to build two near-duplicates of
  the VSM instrument and place them at international sites to form a
  three-site global VSM network. Current electronic industry practice
  of short lifetime cycles leads to improved performance and reduced
  acquisition costs but also to redesign costs and engineering impacts
  that must be minimized. The current VSM instrument status and experience
  gained from working on the original instrument is presented herein and
  used to demonstrate that one can dramatically reduce the estimated
  cost and fabrication time required to duplicate and commission two
  additional instruments.

---------------------------------------------------------
Title: Ca II H &amp; K Spectra From The National Solar Observatory
Authors: Livingston, W. C.; Giampapa, M. S.; Harvey, J. W.; Keil,
   S. L.; Toussaint, R. M.
2008AGUSMSP53B..04L    Altcode:
  When the Sun is observed as a star (i.e., spatially integrated full
  disk) the cores of the chronospheric H and K resonance lines of
  singly ionized calcium show the greatest cycle variability (up to
  40% peak-to-peak) accessible from the ground. Synoptic archives are
  available at monthly intervals from 1974 (Kitt Peak) and for K only
  at almost a daily cadence from 1984 (Sacramento Peak). We discuss
  these time series and compare them with, for example, sunspot numbers
  and magnetic fields. Less frequent are center disk observations in
  which the activity cycle is found to be absent, implying the quiet
  basal atmosphere is constant and not, say, heated by cycle magnetic
  activity. New, near daily, spatially integrated full disk solar data
  from the SOLIS Integrated Sunlight Spectrometer (ISS)agree well with
  the older work. We now propose to produce calibrated (Houtgast 1970;
  Solar Phys 15, 273, high points: 387.5, 395.3, and 402.0 nm), low
  dispersion full disk spectra that may be directly compared with that
  from solar-type stars.

---------------------------------------------------------
Title: Simultaneous Multiwavelength Observations of Magnetic Activity
    in Ultracool Dwarfs. II. Mixed Trends in VB 10 and LSR 1835+32 and
    the Possible Role of Rotation
Authors: Berger, E.; Basri, G.; Gizis, J. E.; Giampapa, M. S.;
   Rutledge, R. E.; Liebert, J.; Martín, E.; Fleming, T. A.; Johns-Krull,
   C. M.; Phan-Bao, N.; Sherry, W. H.
2008ApJ...676.1307B    Altcode: 2007arXiv0710.3383B
  As part of our ongoing investigation of magnetic activity in
  ultracool dwarfs we present simultaneous radio, X-ray, UV, and
  optical observations of LSR1835+32 (M8.5), and simultaneous X-ray
  and UV observations of VB10 (M8), both with a duration of about 9
  hr. LSR1835+32 exhibits persistent radio emission, and Hα variability
  on timescales of 0.5-2 hr. The detected UV flux is consistent with
  photospheric emission, and no X-ray emission is detected to a deep
  limit of L<SUB>X</SUB>/L<SUB>bol</SUB>lesssim 10<SUP>-5.7</SUP>. The
  Hα and radio emission are temporally uncorrelated, and the ratio of
  radio to X-ray luminosity exceeds the correlation seen in F-M6 stars
  by &gt;2 × 10<SUP>4</SUP>. The lack of radio variability during
  four rotations of LSR1835+32 requires a uniform stellar-scale field
  of ~10 G, and indicates that the Hα variability is dominated by much
  smaller scales, &lt;10% of the chromospheric volume. VB10, on the other
  hand, shows correlated flaring and quiescent X-ray and UV emission,
  similar to the behavior of early M dwarfs. Delayed and densely sampled
  optical spectra exhibit a similar range of variability amplitudes and
  timescales. Along with our previous observations of the M8.5 dwarf
  TVLM513-46546 we conclude that late M dwarfs exhibit a mix of activity
  patterns, which points to a transition in the structure and heating
  of the outer atmosphere by large-scale magnetic fields. We find that
  rotation may play a role in generating the fields as evidenced by a
  tentative correlation between radio activity and rotation velocity. The
  X-ray emission, however, shows evidence for supersaturation at vsin
  i &gt; 25 km s<SUP>-1</SUP>, which could be the result of secondary
  effects such as inefficient heating or centrifugal stripping of extended
  coronal loops. These effects may underlie the severe violation of the
  radio/X-ray correlation in ultracool dwarfs.

---------------------------------------------------------
Title: Externally Induced or Internally Produced: What is the Source
    of the Extreme Magnetic Activity Observed in Very Low Mass Stars?
Authors: Howell, Steve B.; Giampapa, Mark; Harrison, Thomas; Hawley,
   Suzanne; Hill, Frank; Honeycutt, Kent; Kafka, Stella; Silvestri,
   Nicole; Szkody, Paula; Walter, Fred; West, Andrew
2008noao.prop...95H    Altcode:
  Recent observations of the very low mass donor stars in short
  period interacting binaries have revealed the presence of active
  chromospheres. Our group has obtained initial spectra for five such
  systems to date and found evidence of stellar activity in all of
  them, including a brown dwarf mass (0.055 M-sun) donor star. The
  Washington group has obtained a SDSS sample of a number of close, but
  non-interacting white dwarf + red dwarf binaries and find H(alpha)
  emission related to activity. We plan to perform the first detailed
  phase-resolved spectroscopic study of the active chromospheres in
  this set of rapidly rotating (&lt;0.3 day), low mass (&lt;0.25 M-sun),
  fully convective late-type stars and brown dwarfs. Our observational
  goals are to study the extent, nature and short-term changes of these
  active chromospheres on the low mass stars of close binaries. Is
  the extreme activity caused by the low mass star itself or externally
  driven by tidal or magnetic forces? The long term goals are to complete
  a large enough sample (~10 systems) to provide statistically useful
  measurements and to use the extended time allocation to obtain long term
  “coverage" spectra of each system to monitor, measure, and understand
  the solar-type cycles likely to be present.

---------------------------------------------------------
Title: Simultaneous Multiwavelength Observations of Magnetic
    Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5
    Dwarf TVLM 513-46546
Authors: Berger, E.; Gizis, J. E.; Giampapa, M. S.; Rutledge, R. E.;
   Liebert, J.; Martín, E.; Basri, G.; Fleming, T. A.; Johns-Krull,
   C. M.; Phan-Bao, N.; Sherry, W. H.
2008ApJ...673.1080B    Altcode: 2007arXiv0708.1511B
  We present the first simultaneous radio, X-ray, ultraviolet, and
  optical spectroscopic observations of the M8.5 dwarf TVLM 513-46546,
  with a duration of 9 hr. These observations are part of a program to
  study the origin of magnetic activity in ultracool dwarfs, and its
  impact on chromospheric and coronal emission. Here we detect steady
  quiescent radio emission superposed with multiple short-duration, highly
  polarized flares; there is no evidence for periodic bursts previously
  reported for this object, indicating their transient nature. We also
  detect soft X-ray emission, with L<SUB>X</SUB>/L<SUB>bol</SUB> ≈
  10<SUP>-5.1</SUP>, the faintest to date for any object later than M5,
  and a possible X-ray flare. TVLM 513-46546 continues the trend of severe
  violation of the radio/X-ray correlation in ultracool dwarfs, by nearly
  4 orders of magnitude. From the optical spectroscopy we find that the
  Balmer line luminosity exceeds the X-ray luminosity by a factor of a
  few, ruling out chromospheric heating by coronal X-ray emission. More
  importantly, we detect sinusoidal Hα and Hβ equivalent width light
  curves with a period of 2 hr, matching the rotation period of TVLM
  513-46546. This behavior points to a corotating chromospheric hot spot
  or an extended magnetic structure, with a covering fraction of about
  50%. This feature may be transitory based on the apparent decline in
  light-curve peak during the four observed maxima. From the radio data
  we infer a large-scale and steady magnetic field of ~10<SUP>2</SUP>
  G. A large-scale field is also required by the sinusoidal Balmer
  line emission. The radio flares, on the other hand, are produced in a
  component of the field with a strength of ~3 kG and a likely multipolar
  configuration. The overall lack of correlation between the various
  activity indicators suggests that the short-duration radio flares do
  not have a strong influence on the chromosphere and corona, and that
  the chromospheric emission is not the result of coronal heating.

---------------------------------------------------------
Title: The First MOTESS-GNAT Variable-Star Survey
Authors: Kraus, Adam L.; Craine, Eric R.; Giampapa, Mark S.; Scharlach,
   Werner W. G.; Tucker, Roy A.
2007AJ....134.1488K    Altcode:
  We present the results of the first MOTESS-GNAT variable-star survey,
  a deep, wide-field variability survey conducted over 2 yr with a total
  sky coverage of 300 deg<SUP>2</SUP>. In this survey, we identified
  26,042 variable-star candidates with magnitudes R = 13-19, including
  5271 that are periodic at the 99% confidence level. We recovered 59
  out of 68 members of the General Catalogue of Variable Stars (GCVS)
  that are in this brightness range. We discuss the implications for
  completeness and accuracy for both this survey and the GCVS; the
  implied completeness for distinctly classifiable variable stars in
  our survey is ~85%-90%. We also discuss some of the caveats of our
  survey results. We conclude that this instrument design is ideal for an
  inexpensive, longitudinally distributed telescope network that could
  be used to study faint or rare transient phenomena in a previously
  unexplored regime of parameter space.

---------------------------------------------------------
Title: Variability of Young Solar-Type Stars in the Pleiades Open
    Cluster
Authors: Giampapa, Mark S.; Sherry, W. S.; Craine, E. R.; Tucker, R.
2007AAS...210.2301G    Altcode: 2007BAAS...39..128G
  We present a preliminary report on a program of photometric
  monitoring of the solar-type stars in the young Pleiades open
  cluster. Specifically, we report on the results for 37 nights of
  observation in our survey region that includes 12 solar-type Pleiades
  members. The goal of the program is to characterize the short- and
  long-term brightness variability of young solar-type stars during
  the epoch of the formation and early evolution of young planetary
  atmospheres. <P />This work is supported in part by a joint grant from
  the NASA Astrobiology Institute to the University of Arizona and the
  NOAO/NSO. The NSO is operated by AURA under a cooperative agreement
  with the NSF.

---------------------------------------------------------
Title: Sun-as-a-Star Spectrum Variations 1974-2006
Authors: Livingston, W.; Wallace, L.; White, O. R.; Giampapa, M. S.
2007ApJ...657.1137L    Altcode: 2006astro.ph.12554L
  We have observed selected Fraunhofer lines, both integrated over
  the full disk and for a small circular region near the center of the
  solar disk, on 1215 days over the past 30 years. Our full disk results
  for the chromosphere show that Ca II K 3933 Å nicely tracks the 11
  yr magnetic cycle based on sunspot number, with a peak amplitude in
  central intensity of ~37%. The wavelength of the midline core absorption
  feature, called K3, referenced to nearby photospheric Fe, displays
  an activity cycle variation with an amplitude of 3 mÅ (6 mÅ center
  disk). Other chromospheric lines, such as He I 10830 Å, Ca II 8542 Å,
  Hα, and the CN 3883 Å bandhead, track Ca II K intensity with lower
  relative amplitudes. In the low photosphere, temperature-sensitive C I
  5380 Å appears constant in intensity to 0.2%. In the high photosphere,
  the cores of strong Fe I lines, Na D1 and D2, and the Mg I b lines,
  present a puzzling signal, perhaps indicating a role for the 22 yr Hale
  cycle. Solar minimum around 1985 was clearly seen, but the following
  minimum in 1996 was missing. Our center disk results show that both
  Ca II K and C I 5380 Å intensities are constant, indicating that the
  basal quiet atmosphere is unaffected by cycle magnetism within our
  observational error. A lower limit to the Ca II K central intensity
  atmosphere is 0.040. This possibly represents conditions as they were
  during the Maunder minimum. Converted to the Mount Wilson S-index
  (H+K index), the Sun center disk is at the lower activity limit for
  solar-type stars. An appendix provides instructions for URL access to
  both the raw and reduced data.

---------------------------------------------------------
Title: A Survey of Chromospheric Activity in the Solar-Type Stars
    in the Open Cluster M67
Authors: Giampapa, Mark S.; Hall, Jeffrey C.; Radick, Richard R.;
   Baliunas, Sallie L.
2006ApJ...651..444G    Altcode: 2006astro.ph..7313G
  We present the results of a spectroscopic survey of the Ca II H and K
  core strengths in a sample of 60 solar-type stars that are members of
  the solar-age and solar-metallicity open cluster M67. We adopt the HK
  index, defined as the summed H+K core strengths in 1 Å bandpasses
  centered on the H and K lines, respectively, as a measure of the
  chromospheric activity that is present. We compare the distribution of
  mean HK index values for the M67 solar-type stars with the variation
  of this index as measured for the Sun during the contemporary solar
  cycle. We find that the stellar distribution in our HK index is broader
  than that for the solar cycle. Approximately 17% of the M67 Sun-like
  stars exhibit average HK indices that are less than solar minimum. About
  7%-12% are characterized by relatively high activity in excess of solar
  maximum values, while 72%-80% of the solar analogs exhibit Ca II H+K
  strengths within the range of the modern solar cycle. The ranges given
  reflect uncertainties in the most representative value of the maximum
  in the HK index to adopt for the solar cycle variations observed
  during the period AD 1976-2004. Thus, ~20%-30% of our homogeneous
  sample of Sun-like stars have mean chromospheric H+K strengths that
  are outside the range of the contemporary solar cycle. Any cycle-like
  variability that is present in the M67 solar-type stars appears to be
  characterized by periods greater than ~6 yr. Finally, we estimate a mean
  chromospheric age for M67 in the range of 3.8-4.3 Gyr. <P />The results
  presented herein are based on data obtained at the WIYN telescope and
  at the McMath-Pierce Solar Telescope. The WIYN Observatory is a joint
  facility of the University of Wisconsin-Madison, Indiana University,
  Yale University, and the National Optical Astronomy Observatory. The
  McMath-Pierce Solar Telescope Facility is operated by the National
  Solar Observatory for the National Science Foundation. This paper is
  WIYN Open Cluster Study XXVIII in the series.

---------------------------------------------------------
Title: Age-Activity Correlation at Young Stellar Ages
Authors: Giampapa, Mark; Sherry, William
2006noao.prop..321G    Altcode:
  We propose to utilize WIYN/Hydra to conduct a survey of the Ca II H
  &amp; K resonance line profiles in the solar-type stars in the young (~
  100 Myr) Pleiades cluster. The results of this program will represent
  the first comprehensive survey of chromospheric Ca II strengths and line
  shapes in the young solar-type members of the Pleiades. We will use
  the measured chromospheric Ca II H&amp; K line strengths to establish
  the empirical calibration between Ca II chromospheric emission and
  stellar age at young ages ~ 100 Myr. We will also directly compare the
  range of Ca II emission encountered in the young Pleiades sun-like
  stars to the range in variation of Ca II core emission seen in the
  contemporary Sun during the course of the modern solar cycle as well as
  to the results of our prior WIYN/Hydra survey of the solar-type stars
  in the solar-age cluster, M67. Finally, the results of the Pleiades
  survey will be compared to that obtained in our proposed Ca II survey
  of the solar-type stars in the intermediate- age cluster NGC 752 (1.8
  Gyr). The combined results of these programs will yield an accurate
  calibration of the age-activity correlation, including the dispersion
  in this correlation due to the range of activity in sun-like stars at a
  given age, extending from cluster ages ~ 0.1 Gyr to ~ 4.5 Gyr. Finally,
  the intercomparison of the survey results for the Pleiades, NGC 752,
  M67, and the Sun, will yield quantitative insight on the evolution of
  the ranges in cycle-related chromospheric activity from ~ 100 Myr to
  solar age.

---------------------------------------------------------
Title: Collaborative Research Opportunities with the Global Network
of Astronomical Telescopes (GNAT): Variable Star Research
Authors: Craine, E. R.; Tucker, R. A.; Kraus, A. L.; Culver, R. B.;
   Giampapa, M. S.
2006SASS...25..111C    Altcode:
  The Global Network of Astronomical Telescopes (GNAT) is modeling
  its observing system on a network of scan-mode telescopes following
  the designs of the Moving Object and Transient Event Search System
  (MOTESS), implemented at Goodricke-Pigott Observatory in Tucson,
  Arizona. GNAT has developed a comprehensive data pipeline for extracting
  photometric measurements of all of the stars observed in each of the
  discrete declination bands observed with the scan-mode system. This
  enormous volume of observations is leading to an aggressive program
  of discovery of objects that are in many cases of great interest in
  terms of follow-up observations. GNAT is reaching out to both the
  professional and amateur astronomy communities to identify potential
  collaborators who are interested in participating in a wide variety
  of follow-up research programs.

---------------------------------------------------------
Title: Structure and Availability of the MOTESS-GNAT Variable
    Star Surveys
Authors: Craine, E. R.; Kraus, A. L.; Giampapa, M. S.; Scharlach,
   W. W. G.; Tucker, R. A.
2005AAS...20712212C    Altcode: 2005BAAS...37.1365C
  The Moving Object Transient Event Search System (MOTESS) has resulted
  in hardware and data streams that are being used as prototypes for the
  Global Network of Astronomical Telescopes (GNAT) photometric monitoring
  systems. Multiple telescopes are operated in scan mode to collect CCD
  imagery of the sky, which is subsequently processed through a prototype
  GNAT data reduction pipeline. This process leads to large arrays of
  differential time series photometry for all of the detectable stars in
  the survey band. The first of several planned surveys is now complete,
  resulting in the MOTESS-GNAT MG1 variable star catalog. The MG1 survey
  is at a declination of 03d18m with a width of 48-arcmin. The survey
  has been reduced to observations of approximately 1.6 million stars
  with a detection limit of R=19; the MG1 variable star catalog contains
  26,042 variable star candidates with R = 13-19, including 5,271 which
  are periodic at the 99% confidence level. In this presentation we
  describe the structure of the catalog and its components and provide
  details on accessing these data. We conclude with a status report on
  subsequent MOTESS GNAT variable star survey programs.

---------------------------------------------------------
Title: Chromospheric Activity at Intermediate Ages
Authors: Giampapa, Mark; Stauffer, John; Deliyannis, Constantine;
   Sherry, William
2005noao.prop...84G    Altcode:
  The calibration of the empirical relation between Ca II chromospheric
  strength and stellar age between 0.6 Gyr (Hyades) and 4.0 - 5 Gyr
  (M67 and the Sun) relies on the uncertain determination of ages
  for individual field stars in the solar neighborhood. We therefore
  propose to obtain WIYN/Hydra spectra of ~ 100 solar-type dwarf stars
  in the 1.8 Gyr old open cluster, NGC 752. This cluster contains a
  sample of solar-type dwarfs that is homogeneous in age and chemical
  composition. Furthermore, NGC 752 is the nearest-and hence brightest-
  cluster at an age ~ 2 Gyr. The results will yield an improved
  calibration of the age-activity relation at intermediate ages. In
  addition, we will determine if the chromospheric Ca II strengths for the
  solar-type stars in NGC 752 lie in the so-called "Vaughan-Preston Gap”-
  an apparent discontinuity in the Ca II H&amp; K strength-(B-V) diagram
  found for field stars in the solar neighborhood. Our data will yield
  insight on the two proposed origins for the gap, namely, that it is a
  result of two different modes of dynamo action or that it is actually
  an artifact of a discontinuity in the local star formation rate. This
  is a resubmission of a previously approved proposal that was allocated
  two nights in 2004 November. The time was lost to instrument problems
  (Hydra gripper malfunctions) and weather. No usable data were obtained.

---------------------------------------------------------
Title: The Magnetic Properties of an L Dwarf Derived from Simultaneous
    Radio, X-Ray, and Hα Observations
Authors: Berger, E.; Rutledge, R. E.; Reid, I. N.; Bildsten, L.;
   Gizis, J. E.; Liebert, J.; Martín, E.; Basri, G.; Jayawardhana, R.;
   Brandeker, A.; Fleming, T. A.; Johns-Krull, C. M.; Giampapa, M. S.;
   Hawley, S. L.; Schmitt, J. H. M. M.
2005ApJ...627..960B    Altcode: 2005astro.ph..2384B
  We present the first simultaneous, multiwavelength observations of
  an L dwarf, the L3.5 candidate brown dwarf 2MASS J00361617+1821104,
  conducted with the Very Large Array, the Chandra X-Ray Observatory,
  and the Kitt Peak 4 m telescope. We detect strongly variable
  and periodic radio emission (P=3 hr) with a fraction of about
  60% circular polarization. No X-ray emission is detected to a
  limit of L<SUB>X</SUB>/L<SUB>bol</SUB>&lt;~2×10<SUP>-5</SUP>,
  several hundred times below the saturation level observed in early
  M dwarfs. Similarly, we do not detect Hα emission to a limit of
  L<SUB>Hα</SUB>/L<SUB>bol</SUB>&lt;~2×10<SUP>-7</SUP>, the deepest for
  any L dwarf observed to date. The ratio of radio to X-ray luminosity
  is at least 4 orders of magnitude in excess of that observed in a
  wide range of active stars (including M dwarfs), providing the first
  direct confirmation that late-M and L dwarfs violate the radio/X-ray
  correlation. The radio emission is due to gyrosynchrotron radiation
  in a large-scale magnetic field of about 175 G, which is maintained
  on timescales longer than 3 yr. The detected 3 hr period may be due
  to (1) the orbital motion of a companion at a separation of about 5
  stellar radii, similar to the configuration of RS CVn systems, (2)
  an equatorial rotation velocity of about 37 km s<SUP>-1</SUP> and an
  anchored, long-lived magnetic field, or (3) periodic release of magnetic
  stresses in the form of weak flares. In the case of orbital motion, the
  magnetic activity may be induced by the companion, possibly explaining
  the unusual pattern of activity and the long-lived signal. We conclude
  that fully convective stars can maintain a large-scale and stable
  magnetic field, but the lack of X-ray and Hα emission indicates that
  the atmospheric conditions are markedly different than in early-type
  stars and even M dwarfs. Similar observations are therefore invaluable
  for probing both the internal and external structure of low-mass stars
  and substellar objects, and for providing constraints on dynamo models.

---------------------------------------------------------
Title: The Sun, Solar Analogs and the Climate
Authors: Haigh, Joanna D.; Lockwood, Michael; Giampapa, Mark S.;
   Rüedi, Isabelle; Güdel, Manuel; Schmutz, Werner
2005ssac.conf.....H    Altcode: 2005SAAS...34.....H
  This book presents the lecture notes of the 34th Saas-Fee Advanced
  Course "The Sun, Solar Analogs and the Climate" given by leading
  scientists in the field. Emphasis is on the observed variability of
  the Sun and the present understanding of the variability's origin
  as well as its impact on the Earth's climate. The solar variability
  is then studied in the broader context of solar-type stars, allowing
  for better understanding of the solar-activity cycle and the magnetic
  activity in general. This book provides an accessible and up-to-date
  introduction to the field for graduate students and serves as a modern
  source of reference for active researchers in this field.

---------------------------------------------------------
Title: Stellar analogs of solar activity: the Sun in a stellar context
Authors: Giampapa, Mark S.
2005ssac.conf..307G    Altcode: 2005SAAS...34..307G
  Contents: 1. Introduction. 2. Stellar cycles. 3. Brightness changes
  in solar-type stars. 4. Activity in solar analogs. 5. Stellar surface
  inhomogeneities. 6. The coronae of solar analogs, low mass stars,
  and brown dwarfs. 7. The early Sun. 8. Stellar activity and extrasolar
  planets.

---------------------------------------------------------
Title: Photometric Precisions in the Prototype MOTESS-GNAT Surveys
Authors: Giampapa, M. S.; Kraus, A. L.; Craine, E. R.; Sherry, W. H.;
   Tucker, R. A.
2004AAS...205.1403G    Altcode: 2004BAAS...36.1360G
  The MG1 and MG2 MOTESS-GNAT surveys were conducted as 48-arcmin
  wide scan-mode CCD imaging surveys of selected areas of the sky in
  an efficient and highly successful asteroid search program. The
  images were reduced photometrically as a test of a prototype of
  a longitudinally distributed network of photometric scan-mode
  telescopes for the Global Network of Astronomical Telescopes,
  Inc. (GNAT). The MG1 and MG2 surveys, which are unfiltered, are
  centered at declinations +03<SUP>o</SUP> 18<SUP></SUP> m 20<SUP></SUP>
  s (MG1) and +02<SUP>o</SUP> 05<SUP></SUP> m 00<SUP></SUP> s (MG2),
  respectively. Although the source data were originally intended for
  astrometric use, they nonetheless have yielded a great deal of useful
  stellar brightness data. As such, they serve as excellent test-beds
  for both future GNAT photometry surveys and as valuable sources of
  new scientific discovery and analysis. To assist in defining some of
  the possible serendipitous programs using the MG1 and MG2 Surveys, we
  present in this poster an analysis of the photometric precisions that
  are attained in these data sets. <P />This effort is supported in part
  by the National Aeronautics and Space Administration through the NASA
  Astrobiology Institute under Cooperative Agreement No. CAN-02-OSS-02
  issued through the Office of Space Science. The NSO and the NOAO are
  operated by AURA for the NSF.

---------------------------------------------------------
Title: A Summary of Known Variable Stars in the MOTESS-GNAT MG1
    Survey and the Status of Future Surveys
Authors: Craine, E. R.; Scharlach, W. G. G.; Kraus, A. L.; Giampapa,
   M. S.; Tucker, R. A.
2004AAS...205.1402C    Altcode: 2004BAAS...36Q1360C
  The MG1 Survey is a two year unfiltered, scan-mode CCD imaging survey
  of a 48-arcmin wide band centered at declination +03° 18m 20s. The
  MG1 survey has yielded open channel photometry of about 2.1 million
  stars, of which some 35,000 were identified as likely variable star
  candidates. Of those 35,000 only about 200 are cataloged in the
  GCVS. In this poster we summarize the statistics of the detections
  of known variable stars which were made using the MG1 data. The
  results will be used to improve the methods and techniques that will
  be employed in future GNAT scan-mode surveys. We also indicate how
  these data can be used to develop useful student projects. Six new
  scan-mode telescopes are under construction for the Global Network of
  Astronomical Telescopes, Inc. (GNAT), effective October 2004. Three of
  these telescopes are expected to become operational during the winter of
  2004-05 and will be sited in Southern Arizona as a coordinated triplet
  of photometric CCD imaging instruments. Another existing telescope will
  be operational before December 2004. All four of these telescopes will
  be used primarily to gather low amplitude variability data on Solar-type
  stars in the Pleiades and M67, respectively, in a study of parameters
  that control the ambient radiative and particle environments of the
  habitable zones around such stars. Because the telescopes will operate
  nightly for several years there will be a huge collateral accumulation
  of photometric data from 24-hour long strips of the sky approximately
  48 arcmin wide. Nightly bandpass photometry will be obtained for an
  estimated 4-6 million stars, hence yielding a large archive of data
  for a wide variety of interesting research projects. We would like to
  attract collaborators comprised of students, professional and amateur
  astronomers. The next two surveys to be run are the G1 Survey, at a
  declination of approximately +24° (one telescope and a single filter),
  and the G2 survey, at a declination of approximately +12° (three
  telescopes and two filters). The exact declinations will be chosen to
  maximize the number of solar-type stars in the respective fields. We
  outline in this poster several of the possible research projects that
  offer opportunities for collaboration. <P />This material is based
  upon work supported in part by the National Aeronautics and Space
  Administration through the NASA Astrobiology Institute under Cooperative
  Agreement No. CAN-02-OSS-02 issued through the Office of Space Science.

---------------------------------------------------------
Title: High Amplitude Variable Stars in the MOTESS-GNAT MG1 Survey
Authors: Culver, R. B.; Craine, E. R.; Kraus, A. L.; Giampapa, M. S.;
   Tucker, R. A.
2004AAS...205.1404C    Altcode: 2004BAAS...36R1360C
  The Moving Object and Transient Event Search System (MOTESS) is
  a triplet of scan-mode telescopes located in Tucson, Arizona, and
  devised originally for high efficiency, unfiltered astrometric asteroid
  searches. Recently, the hardware system has been adopted by the Global
  Network of Astronomical Telescopes, Inc. (GNAT), as a prototype for a
  much expanded network of longitudinally distributed telescopes operating
  primarily as a high efficiency, high time frequency photometric survey
  system. The original MOTESS asteroid survey was operated for just over
  two years at a declination of +03° 18m 20s. We developed a photometric
  data reduction pipeline to process the extensive archive of deep,
  unfiltered digital images. As a result, we now have two years of open
  channel photometry for about 2.1 million stars, of which some 35,000
  are identified as likely variable star candidates. Of those 35,000,
  only ∼ 200 are cataloged in the General Catalogue of Variable Stars
  (GCVS). Our primary purpose has been to use this survey, which we call
  the MG1 Survey, as a proof-of-principle test-bed of our data reduction
  system. In the process, our work has serendipitously yielded an enormous
  amount of useful data, including tens of thousands of new variable
  star discoveries. In this presentation, we discuss specifically our
  efforts to characterize the highest amplitude variables in the MG1
  Variable Star Catalog. <P />This work has been supported in part by
  Walker &amp; Company.

---------------------------------------------------------
Title: Extragalactic Variable Objects in GNAT Image Archives
Authors: Craine, E. R.; Culver, R. B.; Giampapa, M. S.; Kraus, A. L.;
   Tucker, R. A.
2004AAS...204.4018C    Altcode: 2004BAAS...36..719C
  The Global Network of Astronomical Telescopes (GNAT) has used the
  image output of its prototype, the Moving Object and Transient Event
  Search System (MOTESS), to create a photometric database of two years
  observations of over 2.5 million celestial point sources. These
  observations have been made through the full 24-hr range of Right
  Ascension at a fixed declination of +3d18m, with a field of view
  of 48 arcmin. The integration time in each field is 191 sec allowing
  detection of objects as faint as 20 mag. This catalog has been searched
  for variable objects at the 6-sigma level, resulting in a list of about
  36,000 newly discovered variables. The majority of these objects are
  stars of a wide range of types, however, some of the variables are
  expected to be extragalactic objects. We report progress on a program
  to identify known extragalactic sources in the observed region of the
  sky and to develop light curves for these objects using the archived
  GNAT images. <P />We appreciate the support of Walker &amp; Company
  for this research program.

---------------------------------------------------------
Title: Early Results from SOLIS
Authors: Harvey, J.; Giampapa, M.; Henney, C.; Keller, C.; Jones, H.
2004AAS...204.3701H    Altcode: 2004BAAS...36..708H
  SOLIS (Synoptic Optical Long-Term Investigations of the Sun)
  is a project that is replacing antiquated synoptic observing
  equipment at the National Solar Observatory. SOLIS consists of
  a suite of three instruments on an equatorial mount that will be
  installed on Kitt Peak in April 2004. The major SOLIS instrument
  is a vector spectromagnetograph (VSM) that maps magnetic fields
  across the full solar disk using a slit spectrograph and one arc
  sec pixels. Limited daily observations started at a temporary site
  in August, 2003 and include line-of-sight component magnetograms in
  the photosphere and chromosphere and, for the first time, full-disk
  vector magnetograms. At a medium scan speed ( ∼ 10 minutes for the
  full disk) noise is less than 1 Mx/cm<SUP>2</SUP>. This low noise,
  combined with negligible instrumental polarization and well resolved
  spectral line profiles, yields moderate resolution magnetograms of
  unprecedented quality. Observations show magnetic flux nearly everywhere
  in the photosphere from the disk center to the solar limb. Weak,
  intranetwork fields are now routinely observed and show a tendency to
  be of opposite polarity to the stronger surrounding fields. Diffuse
  fields surround decaying active regions and appear to be distinct from
  canopy fields. Vector magnetograms easily show the radial orientation
  of network fields, and the diffuse component surrounding decaying active
  regions. Near the disk center, the transverse magnetic fields of network
  elements change on a time scale of minutes. Detailed quantitative
  calibration of the observations is in progress. Good results have been
  obtained from the other SOLIS instruments: a full-disk filter imager at
  several narrow wavelengths and a double-pass grating spectrograph that
  provides high-accuracy line spectra of integrated sunlight. SOLIS data
  are freely available via the Internet and users are invited to submit
  observing time requests for special observations. The National Solar
  Observatory is operated by AURA, Inc. under a cooperative agreement
  with the National Science Foundation. Additional support for the
  development of SOLIS from NASA and ONR is gratefully acknowledged.

---------------------------------------------------------
Title: GNAT/MOTESS Data Pipeline and Variable Star Catalog
Authors: Kraus, A. L.; Craine, E. R.; Giampapa, M. S.; Tucker, R. A.
2003AAS...203.0903K    Altcode: 2003BAAS...35.1218K
  The Global Network of Astronomical Telescopes (GNAT) is testing a
  prototype system of multiple scan-mode telescopes, the Moving Object
  and Transient Event Search System (MOTESS), at the Goodricke-Pigott
  Observatory in Tucson, Arizona. A primary goal of GNAT has been
  to develop a data pipeline for reduction of sky survey CCD images
  to extract photometric data for all of the stars detected in the
  images. This effort is now complete and we describe here the structure
  of the data reduction system as it has been applied to the first two
  years of observations. The system relies on IRAF at its core, augmented
  by several custom routines for handling of the raw photometry. To
  date, the system has been applied to a single declination of scanning,
  +3d18m20s, and has resulted in systematic photometric observations of
  about 1.5-2.5 million stars. Processing of these data has yielded a
  list of about 35,000 stars which are convincingly variable. All but
  about 200 of these stars are new variable discoveries. Funding for
  this project was provided by an NSF REU grant and an anonymous donor.

---------------------------------------------------------
Title: Known Variable Stars in GNAT/MOTESS Data
Authors: Craine, E. R.; Kraus, A. L.; Giampapa, M. S.; Tucker, R. A.;
   Scharlach, W.
2003AAS...203.0904C    Altcode: 2003BAAS...35.1218C
  The Global Network of Astronomical Telescopes (GNAT) is using as
  a hardware prototype a system of multiple scan mode telescopes of
  the Moving Object and Transient Event Search System (MOTESS) of the
  Goodricke-Pigott Observatory in Tucson, Arizona. During the first two
  years of operation of the system, approximately 35,000 variable stars
  were observed of which approximately 200 were previously known. In this
  paper we provide details of the GNAT observations of the previously
  known variable stars, compare these results with previously published
  data, and use the observational results to help characterize the
  observational system. Funding for this project was provided by an
  anonymous donor.

---------------------------------------------------------
Title: First Results from SOLIS
Authors: Harvey, J.; Giampapa, M.; Henney, C.; Jones, H.; Keller, C.
2003AGUFMSH42B0545H    Altcode:
  SOLIS (Synoptic Optical Long-term Investigations of the Sun) is a
  project to replace antiquated synoptic observing equipment at the
  National Solar Observatory. SOLIS includes a suite of three instruments
  on an equatorial mount originally installed at a site in Tucson and will
  be moved to Kitt Peak before the end of 2003. The major SOLIS instrument
  is a vector spectromagnetograph that maps magnetic fields across the
  full solar disk using a slit spectrograph and one arc sec pixels. Daily
  observations include several line-of-sight component magnetograms in the
  photosphere and chromosphere and, for the first time, full-disk vector
  magnetograms. At a medium scan speed ( ∼10 minutes for the full disk)
  noise is less than 1 Mx/cm<SUP>2</SUP>. This low noise, combined with
  negligible instrumental polarization and well resolved spectral line
  profiles, yields moderate resolution magnetograms of unprecedented
  quality. Sample observations show magnetic flux nearly everywhere
  in the photosphere from the disk center to the solar limb. The flux
  is organized in large scale patterns that heretofore had been visible
  only in strong flux elements or after substantial spatial smearing. Good
  results have been obtained from the other SOLIS instruments: a full-disk
  filter imager at several narrow wavelengths and a grating spectrograph
  that provides high-accuracy line spectra of integrated sunlight. SOLIS
  data are freely available via the Internet and users may submit
  observing time requests for special observations. The National Solar
  Observatory is operated by AURA, Inc. under a cooperative agreement
  with the National Science Foundation. Additional support for the
  development of SOLIS from NASA and ONR is gratefully acknowledged.

---------------------------------------------------------
Title: The Suns of M67
Authors: Giampapa, M.
2003csss...12...91G    Altcode:
  We discuss the methodology and some preliminary results of a survey
  of the chromspheric Ca II H &amp; K line strengths in a sample of
  solar-type stars in the galactic open cluster M67. We compare the
  distribution of H&amp;K line strength among the solar counterparts in
  this cluster with that seen in the contemporary Sun during the course
  of its 11-year cycle.

---------------------------------------------------------
Title: The Quiescent Corona of VB 10
Authors: Fleming, Thomas A.; Giampapa, Mark S.; Garza, David
2003ApJ...594..982F    Altcode:
  We present results from a Chandra ACIS observation of the M8 dwarf
  star VB 10, a star near the hydrogen-burning mass limit. Until now,
  VB 10 has only been detected to flare at X-ray wavelengths. We can now
  report that nonflare, “quiescent,” X-ray emission has been detected
  with a luminosity, L<SUB>X</SUB>=(2.4+/-0.05)×10<SUP>25</SUP> ergs
  s<SUP>-1</SUP> and log(L<SUB>X</SUB>/L<SUB>bol</SUB>)=-4.9. This is
  consistent with the previous ROSAT nondetections of quiescent emission
  from VB 10. We discuss the implications of this discovery for the
  nature of coronae in ultracool dwarfs.

---------------------------------------------------------
Title: Chromospheric Activity in Solar-Type Stars
Authors: Giampapa, M. S.; Hall, J. C.; Radick, R. R.; Baliunas, S. L.
2003SPD....34.0710G    Altcode: 2003BAAS...35..821G
  We present an update on the results of a survey of chromospheric
  activity in the solar-age and solar-metallicity open cluster, M67. The
  objective of the survey is to gain insight on the potential range of
  amplitudes of the solar cycle through observations of solar analogs
  that are presumably at random phases in their cycles of magnetic
  activity. We find that there is a significant overlap of the levels
  of Ca II H and K emission in the sun-like stars in M67 with the
  range of activity seen in the contemporary solar cycle. However,
  there are also stars that exhibit levels of activity outside of this
  range, including stars that are "super-solar" in their Ca II H and
  K emission. The implications of these results will be discussed. <P
  />The data presented in this investigation were obtained with the
  WIYN 3.5-m telescope on Kitt Peak. The WIYN Observatory is a joint
  facility of the University of Wisconsin-Madison, Indiana University,
  Yale University, and the NOAO. The NSO and the NOAO are operated by
  AURA for the National Science Foundation.

---------------------------------------------------------
Title: SOLIS: an innovative suite of synoptic instruments
Authors: Keller, Christoph U.; Harvey, John W.; Giampapa, Mark S.
2003SPIE.4853..194K    Altcode:
  SOLIS (Synoptic Optical Long-term Investigations of the Sun) is
  a suite of three innovative instruments under construction that
  will greatly improve ground-based synoptic solar observations. The
  Vector Spectromagnetograph (VSM) is a compact, high-throughput
  vector-polarimeter with an active secondary mirror, an actively
  controlled grating spectrograph, and two high-speed cameras with
  silicon-on-CMOS-multiplexer hybrid focal plane arrays. It will measure
  the magnetic field strength and direction over the full solar disk
  within 15 minutes. The Full-Disk Patrol (FDP) takes full-disk solar
  intensity and Doppler images in various spectral lines and in the
  continuum at a high cadence through liquid-crystal tuned birefringent
  filters. The Integrated Sunlight Spectrometer (ISS) uses a fiber-fed
  spectrograph to measure minute changes of the Sun-as-a-star in
  many spectral lines. A high degree of automation and remote control
  provides fast user access to data and flexible interaction with the
  data-collection process. SOLIS is currently in the final assembly
  phase and will become operational early in 2003.

---------------------------------------------------------
Title: Emission line variability in a newly discovered 2MASS star
Authors: Giampapa, Mark; Liebert, James; Reid, Neil; Cruz, Kelle
2003noao.prop..234G    Altcode:
  We propose to utilize the HET/HRS to obtain spectra of the newly
  discovered, low-mass star 2M075223.9+161215. The primary objectives
  are to search for (1) variability in the strength and position of
  the H(alpha) emission line profile and (2) determine if the Li I
  (lambda)6707 feature is present to confirm whether this enigmatic object
  is a field brown dwarf. Previous HET/HRS spectra of this object were
  obtained on the night of UT 01 April 2002. However, the S/N in the Li
  region was insufficient to arrive at a definitive conclusion concerning
  the presence of lithium in 2M075223.9. The additional spectra will
  be co-added to the previous spectra in order to examine the complex
  (lambda)6707 region in more detail. Of equal importance, the detection
  of either short- or long- term variability will yield insight on the
  origin of the emission line mechanism. The two competing models for the
  origin of the strong emission line spectrum involve either strongly
  enhanced chromospheric activity driven by magnetic dynamo action or
  accretion in a low mass binary system.

---------------------------------------------------------
Title: Implementation of the GNAT Network Design and System
    Configurations
Authors: Culver, R. B.; Craine, E. R.; Giampapa, M. S.; Tucker, R. A.;
   Kraus, A. L.
2002AAS...20112202C    Altcode: 2002BAAS...34.1304C
  Following the successful deployment of the three-telescope Moving Object
  Transient Event Search System (MOTESS), which is a model prototype of
  the Global Network of Astronomical Telescopes (GNAT) system, we have
  begun design of a geographically distributed network of 48 automated,
  scan-mode telescopes. During the course of the design effort it has
  become apparent that such a network offers great versatility by virtue
  of a large number of possible telescope and network configurations. This
  versatility allows us to modify such parameters as system limiting
  magnitude, image signal-to-noise ratios, time and frequency of field
  observation, and field of view, among others. In this paper we consider
  some of the most interesting system configurations discussed to date,
  provide a summary of the resultant system parameters and outline the
  nature of the science which can be most efficiently done with each
  configuration. We also discuss practical experience gained to date
  which scales the nature of the effort involved in reconfiguring the
  network to accommodate various types of observations.

---------------------------------------------------------
Title: A Prototype Data Reduction Pipeline for the GNAT System
Authors: Kraus, A. L.; Giampapa, M. S.; Tucker, R. A.; Craine, E. R.
2002AAS...20112203K    Altcode: 2002BAAS...34Q1304K
  The Moving Object and Transient Event Search System (MOTESS) has
  been operating for the past year as a prototype for the Global
  Network of Astronomical Telescopes (GNAT). During this time, it has
  produced approximately 200 nights of observations on a 48-arcminute
  band of declination near the celestial equator. We have developed an
  automated data reduction pipeline that performs aperture photometry
  and differential photometry on the nightly data and then matches
  the results to a standard catalog based on the United States Naval
  Observatory catalog. Objects that match the catalog are added to the
  data library, while unmatched objects are placed into a separate catalog
  for analysis. One data analysis technique we have been exploring is to
  search the new object catalog for transient events such as supernovae
  and cataclysmic variables. We have also been optimizing the pipeline
  so that it can be scaled as additional instruments are added to the
  GNAT network.

---------------------------------------------------------
Title: The Coronae of Low Mass Stars and Brown Dwarfs
Authors: Giampapa, M. S.; Fleming, T. A.
2002ASPC..277..247G    Altcode: 2002sccx.conf..247G
  No abstract at ADS

---------------------------------------------------------
Title: Stellar Variability Observations with MOTESS, a GNAT System
    Prototype
Authors: Craine, E. R.; Giampapa, M. S.; Kraus, A. L.; Tucker, R. A.;
   Scharlach, W.
2002AAS...20112201C    Altcode: 2002BAAS...34.1303C
  The Moving Object Transient Event Search System (MOTESS) is a three
  telescope, scan-mode system developed initially for near-Earth asteroid
  detection, and since adopted as a prototype for a Global Network of
  Astronomical Telescopes (GNAT) system. In this paper we summarize
  photometric characteristics of the prototype telescope network and
  discuss initial results of measurements of stellar variability
  using data obtained during the first full year of operation of
  the system. In the initial data set, 173 known variable stars were
  observed, of which 19 exceeded the useful upper brightness limits of
  the images. The remaining stars ranged down to about 17.5 mag with the
  brightness distribution peak at about 14.5 mag. The most frequently
  occurring types are Mira variables (52), eclipsing systems (33),
  and semi-regulars (25); with the remainder distributed over a wide
  range of variable types. We give examples of data for known variables,
  discuss the likely discovery of new variables and outline a strategy
  for using these data in screening stellar observations suggestive of
  possible planetary transits.

---------------------------------------------------------
Title: Stellar Chromospheres and the Sun
Authors: Giampapa, M.
2002AAS...200.5301G    Altcode: 2002BAAS...34..729G
  Observations combined with the development of semi-empirical models
  show that stellar chromospheres and the solar chromosphere share many
  of the same features. Nevertheless, are homogeneous, single-component
  models of stellar chromospheres adequate representations of their
  atmospheres in the light of observations that clearly indicate the
  multi-component natures of both the solar and stellar chromospheres? Is
  the distinction between "active" and "quiet" chromosphere stars mainly
  due to the fractional area coverage of otherwise identical magnetic
  active regions on their surfaces, or can the distinction be attributed
  primarily to differing heating rates in a relatively homogeneous
  atmosphere? Can single-component, static models successfully account
  for the levels of emission in the dominant radiative coolants in
  stellar chromospheres? How does the radiative energy balance between
  the chromosphere and corona change with effective temperature and
  gravity in the cool half of the H-R diagram? Is there evidence for
  "cool chromospheres" in main sequence stars? These issues will be
  addressed in an effort to compare and contrast stellar chromospheres
  with that of the Sun. The National Solar Observatory is operated for
  the National Science Foundation by the Association of Universities
  for Research in Astronomy.

---------------------------------------------------------
Title: Moving Object and Transient Event Search System (MOTESS):
    An Evaluation of Photometric Properties/Low Amplitude Stellar
    Variation Measurements
Authors: Craine, E. R.; Tucker, R. A.; Giampapa, M. S.; Scharlach,
   W. W. G.
2002AAS...200.6412C    Altcode: 2002BAAS...34R.750C
  The Moving Object and Transient Event Search System (MOTESS) is being
  expanded from its original task as an automated, moving object search
  system (astrometric application) to add the transient event detection
  capability (photometric application). In anticipation of this activity,
  photometric reductions of MOTESS images have been systematically
  undertaken to characterize the system in terms of photometric precision
  during a night, light curve stability from night to night and long term
  time series photometry. We discuss the data pipeline, characteristics
  of the system images, and photometric precision as a function of
  brightness of the object observed. We also present example light curves
  of known variable objects as a demonstration of the capabilities of the
  system. In this context we summarize key science programs of the Global
  Network of Automatic Telescopes (GNAT) which are being undertaken with
  the MOTESS facility, including extrasolar planetary transit searches,
  supernovae monitoring and other stellar variability programs.

---------------------------------------------------------
Title: Solar-stellar connections
Authors: Giampapa, M.
2002cosp...34E.638G    Altcode: 2002cosp.meetE.638G
  The observation of the solar cycle with the telescope extends over a few
  centuries while its study at high precisions with modern instrumentation
  is only a few decades old. In fact, the measurement of solar luminosity
  variability at the level of 0.1%, and the correlation of brightness
  changes with the solar cycle of magnetic activity, is less than two
  decades old. Thus, our knowledge of the full range of solar variability
  that may occur is extremely limited. We believe that a substantially
  larger brightness variation occurred during the Maunder minimum from
  AD 1645 to 1715. But, because individual solar cycles are different
  in form, amplitude and length, and because accurate solar data have
  been available only for the most recent cycles, there is no direct
  way of understanding long-term solar variability. The observation of
  solar-type stars, however, can overcome the temporal confines of the
  solar data-base, thereby revealing the potential range and nature of
  solar variability over time scales that are simply not accessible
  to the modern data-base of only a few decades. I will discuss the
  empirical properties of magnetic field-related activity variations in
  solar-type stars and the associated luminosity variability, and compare
  these properties to that of the Sun. In this way, we can gain insight
  on the full range of variability that the Sun can potentially exhibit
  over long time scales. The National Solar Observatory is operated for
  the National Science Foundation by the Association of Universities
  for Research in Astronomy.

---------------------------------------------------------
Title: Limits on Line Bisector Variability for Stars with Extrasolar
    Planets
Authors: Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman,
   T.; Barden, S.; Deming, D.; Livingston, W. C.; Pilachowski, C.
2001AJ....121.1136P    Altcode:
  We present an analysis of high-resolution synoptic spectra of ten F-
  and G-type stars, seven of which exhibit periodic radial velocity
  variations due to the presence of one or more substellar companions. We
  searched for subtle periodic variations in photospheric line asymmetry,
  as characterized by line bisectors. In principle, periodic variations
  in line asymmetry observed at lower spectral resolution could mimic the
  radial velocity signature of a companion, but we find no significant
  evidence of such behavior in our data. Observations were obtained
  from 1998 March to 1999 February using the National Solar Observatory
  (NSO) 1.52 m McMath-Pierce Solar Telescope Facility on Kitt Peak in
  conjunction with the solar-stellar spectrograph, achieving a resolving
  power of 1.2×10<SUP>5</SUP>. To characterize line asymmetry, we
  first measured line bisectors for the unblended Fe I photospheric
  line at 625.26 nm. To improve sensitivity to small fluctuations, we
  then combined points in each bisector to form a velocity displacement
  with respect to the line core. We searched for periodic variations in
  this displacement, finding no substantial difference between stars with
  substellar companions and those without reported companions. We find no
  correlation between bisector velocity displacement and the known orbital
  phase of substellar companions around our target stars. Simulations of
  a periodic signal with noise levels that mimic our measurement errors
  suggest that we can exclude bisector variations with amplitudes greater
  than about 20 m s<SUP>-1</SUP>. These results support the conclusion
  that extrasolar planets best explain the observed periodic variations
  in radial velocity.

---------------------------------------------------------
Title: Photometric Monitoring of M67 with the GNAT 0.5-m Telescope
Authors: Roberts, J. H.; Craine, E. R.; Giampapa, M. S.
2000AAS...197.4004R    Altcode: 2000BAAS...32.1459R
  A long-term program of nightly observations of the solar-age and
  solar-metallicity, galactic open cluster, M67, was initiated with
  the prototype GNAT 0.5-m automated telescope in conjunction with a
  SITe 512 x 512 thermoelectrically cooled CCD. The broad objective
  of this program is to investigate the utilization of the GNAT
  0.5-m telescope for long-term projects requiring high-precision
  photometry. The specific, dual applications include (1) the monitoring
  of low-amplitude luminosity variations in solar-type stars and (2)
  the detection of extrasolar planets via photometric transits. These
  science goals require that precisions of at least a few millimags be
  consistently achieved and maintained. As a prelude to these kinds of
  programs, we obtained a nightly time-series of automated photometric
  observations of M67 on 24 nights during a two month period from
  abbreviated JD51604-JD51679. Unfiltered photometry with an integration
  time of 180 sec per CCD frame was performed. A total of 1,260 frames
  were obtained. For those frames characterized by high signal-to-noise
  ratios, precisions of 4-5 mmag were attained on both an intranight
  and internight basis. No variations that could be attributed to a
  photometric transit event were detected. Further preliminary results
  from this program will be discussed. JR gratefully acknowledges the
  support of the NSF through the NSO/REU program. The NSO is operated
  by AURA under cooperative agreement with the NSF.

---------------------------------------------------------
Title: Red Dwarfs/Flare Stars
Authors: Giampapa, M.
2000eaa..bookE1866G    Altcode:
  The red dwarf stars are main-sequence stars characterized by masses
  in the approximate range from 0.51M⊙ to 0.08M⊙. The upper mass
  limit corresponds to a spectral type of M0 V and the lower limit is
  the critical mass for the onset of nuclear burning in the central cores
  of stars with chemical abundances similar to the Sun. Below the range
  of approximately (0.074-0.08)M⊙ is the realm of substellar...

---------------------------------------------------------
Title: The Coronae of Inactive Low-Mass Dwarfs
Authors: Kashyap, V. L.; Giampapa, M.; Drake, J. J.
2000HEAD....5.4217K    Altcode: 2000BAAS...32.1257K
  We analyze deep EUVE/SW data of two inactive low-mass dM stars GJ 205
  and GJ 411. The spectra do not show any spectral lines that can be
  used for temperature or density diagnostics. We therefore model these
  spectra with different types of Differential Emission Measure (DEM)
  distributions and show that the peak temperature in the corona is
  akin to the Quiet Sun. We also derive constraints on the metallicity
  of the corona of GJ 205, and suggest that compared to its photosphere
  the corona appears to be metal deficient.

---------------------------------------------------------
Title: A Survey of Activity in the Solar-Type Stars in M67
Authors: Giampapa, M. S.; Radick, R. R.; Hall, J. C.; Baliunas, S. L.
2000SPD....3102120G    Altcode: 2000BAAS...32..832G
  We present an update on a long-term study of the solar-type stars in
  the solar-age and solar-metallicity open cluster, M67. The primary
  objective of this program is to gain insight on the possible range of
  solar chromospheric activity and the associated, potential long-term
  variability of the Sun through the observation of stellar analogs of
  the Sun. Spectra in the Ca II H &amp; K line region of over 100 stars
  in M67, including 76 `solar-type' stars (with unreddened colors in
  the range +0.60 &lt;= B-V &lt;= +0.76) and 21 `solar-twins' (+0.63
  &lt;= B-V &lt;= +0.67), were obtained with the 3.5-m WIYN telescope
  on Kitt Peak in conjunction with the Hydra multi-fiber positioner
  to perform multi-object spectroscopy over a 1 degree field. We find
  that the distribution of chromospheric H&amp;K line strengths in
  the solar-type stars is broader than the distribution of H&amp;K line
  emission recorded in modern observations of the Sun, suggesting that the
  potential excursion in the amplitude of the solar cycle is greater than
  what we have seen so far in the contemporary record. Approximately 30%
  of the solar-type stars in M67 exhibit levels of activity that are
  outside the present envelope of solar activity. We interpret this to
  mean that the Sun can be in a state of magnetic activity---either
  exceptional quiescence similar to the Maunder-minimum episode or
  enhanced activity---about 30% of the time. The authors gratefully
  acknowledge both the NOAO Telescope Allocation Committee and the
  WIYN Queue Program for their support of this investigation. The WIYN
  Observatory is a joint facility of the University of Wisconsin-Madison,
  Indiana University, Yale University, and the NOAO. The NSO and NOAO are
  operated by AURA, Inc., under cooperative agreement with the National
  Science Foundation.

---------------------------------------------------------
Title: An X-Ray Flare Detected on the M8 Dwarf VB 10
Authors: Fleming, Thomas A.; Giampapa, Mark S.; Schmitt, Jürgen
   H. M. M.
2000ApJ...533..372F    Altcode: 2000astro.ph..2065F
  We have detected an X-ray flare on the very low mass star VB 10
  (GL 752 B; M8V) using the ROSAT High Resolution Imager. VB 10 is
  the latest type (lowest mass) main-sequence star known to exhibit
  coronal activity. X-rays were detected from the star during a single
  1.1 ks segment of an observation that lasted 22 ks in total. The
  energy released by this flare is on the order of 10<SUP>27</SUP> ergs
  s<SUP>-1</SUP>. This is at least 2 orders of magnitude greater than the
  quiescent X-ray luminosity of VB 10, which has yet to be measured. This
  X-ray flare is very similar in nature to the far-ultraviolet flare
  that was observed by Linsky et al. using the Goddard High Resolution
  Spectrograph onboard the Hubble Space Telescope. We discuss reasons
  for the extreme difference between the flare and quiescent X-ray
  luminosities, including the possibility that VB 10 has no quiescent
  (10<SUP>6</SUP> K) coronal plasma at all.

---------------------------------------------------------
Title: Line Bisector Variations in Stars with Extrasolar Planets
Authors: Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman, T.
1999AAS...19510901P    Altcode: 1999BAAS...31.1533P
  We present the results from a high-resolution, synoptic spectroscopic
  program of observation of ten F- and G-type stars, seven of which
  exhibit periodic radial velocity variations attributed to the
  presence of one or more substellar companions. The observations
  were obtained from 1998 March to 1999 February using the 1.52-m NSO
  McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction
  with the solar-stellar spectrograph. The spectra were acquired with a
  resolving power of approximately 1.2 x 10<SUP>5</SUP>. The line bisector
  was then derived from unblended photospheric features. In particular,
  we define the velocity displacement of the spectral line bisector
  and determine the bisector amplitude for the Fe I absorption line
  at 625.26 nm in order to search for variations in the line asymmetry
  over time. Such variations could mimic Doppler shifts in observations
  with lower spectral resolution. Examination of the bisector velocity
  displacement over the time span of our observations reveals no
  substantial difference between stars with planetary companions and
  those without reported companions. We find no correlation between the
  bisector variations and the orbital phase of a substellar companion
  in any of our target stars. Simulations of a periodic signal with
  noise levels based on our measurement errors suggest that we can
  exclude bisector variations with amplitudes greater than about 20 m
  s<SUP>-1</SUP>. These results support the conclusion that extrasolar
  planets best explain the observed periodic variations in radial
  velocity. This work was supported by a NASA grant to the NOAO under
  the auspices of the Origins of Solar Systems Program. MP gratefully
  acknowledges support from the NSF-sponsored Research Experience for
  Undergraduates (REU) program at the NOAO. The NOAO is operated by AURA,
  Inc., under a cooperative agreement with the NSF.

---------------------------------------------------------
Title: The Suns of M67
Authors: Giampapa, M. S.; Radick, R. R.; Baliunas, S. L.
1999AAS...194.9212G    Altcode: 1999BAAS...31..988G
  The results of our program to survey the level of chromospheric Ca II
  H&amp;K emission in ~ 100 solar analogs in the galactic cluster M67 are
  discussed. This cluster is an appropriate target of observation for
  the study of solar-type stars since it is approximately the same age
  and has the same chemical composition as the Sun. The key objective
  of our program is to investigate the nature of solar variability. In
  particular, we interpret the range of Ca II H&amp;K emission observed
  in the sun-like stars in M67 as indicative of the possible amplitudes
  of cycle-related variability that can occur in the Sun itself. In
  this way, we can efficiently gain insights on the potential long-term
  variability of the Sun that would not otherwise be possible with the
  modern solar Ca II synoptic database of just a few decades. This is
  especially important given that the amplitude of long-term solar
  (and stellar) variations in brightness are correlated with cycle
  variations in chromospheric emission. In view of the fact that the
  Sun is the engine that drives climate on the Earth, any variation
  in the solar “constant" must be taken into account in the study of
  the long-term behavior of the global climate. The NOAO is operated
  by the Association of Universities for Research in Astronomy, Inc.,
  under cooperative agreement with the National Science Foundation.

---------------------------------------------------------
Title: Cycles and Long-Term Variability in Solar-Type Stars
Authors: Giampapa, Mark S.; Radick, Richard R.; Hall, Jeffrey C.;
   Baliunas, Sallie L.
1999noao.prop..226G    Altcode:
  We propose a long-term extension of our current WIYN/Hydra program to
  study chromospheric activity cycles in the `Suns of M67.' Our results
  thus far have revealed that the distribution of activity among the
  solar- type stars in M67 is broader than what would be expected from a
  comparison with the solar cycle. The next step is to determine whether
  our results arise from the cyclic modulation of activity alone or
  if the relative amplitudes of cycles in solar-type stars and the Sun
  are actually similar and the spread in M67 is due to differences in
  the mean level of activity. Only a long-term monitoring program of
  regular observations can address these questions. The results of this
  program are expected to reveal all the potential modes and amplitudes
  of magnetic cycles in sun-like stars and, by inference, in the Sun
  itself, with important implications for dynamo models and models of
  global climate change.

---------------------------------------------------------
Title: Differential Photometry Using the GNAT 0. 5 m Prototype
Authors: Taylor, J. M.; Craine, E. R.; Giampapa, M. S.
1999ASPC..189..238T    Altcode: 1999pcp..conf..238T
  No abstract at ADS

---------------------------------------------------------
Title: X-Ray Activity in the Open Cluster IC 4665
Authors: Giampapa, Mark S.; Prosser, Charles F.; Fleming, Thomas A.
1998ApJ...501..624G    Altcode:
  We present the results of a joint ROSAT High Resolution Imager (HRI)
  and optical investigation of the open cluster IC 4665. The ROSAT data
  contains detections for 28 stellar sources in the field, including 22
  cluster members and candidate members spanning the color range -0.18
  &lt;= (B-V)<SUB>0</SUB> &lt;= 1.63 (~B3-M3). Upper limits are given for
  the remaining members (or candidate members) in the HRI field. Keck
  HIRES spectra have been obtained that yield radial and rotational
  velocity measures, respectively, for faint, low-mass candidate members
  located within the field of the ROSAT HRI observation. In addition,
  photometry of possible optical counterparts to previously uncataloged
  X-ray sources in the HRI field is presented. <P />The trends in
  X-ray properties with B-V color in IC 4665 are found to be quite
  similar to that for other, more nearby young clusters such as the
  Pleiades and α Persei. In particular a maximum in normalized X-ray
  luminosity of log (L<SUB>X</SUB>/L<SUB>bol</SUB>) ~= -3 is observed,
  beginning in the color range of (B-V)<SUB>0</SUB> = 0.7-0.8. This
  is similar to the corresponding color range among Pleiades members,
  in agreement with the earlier estimate by Prosser &amp; Giampapa
  that the age of IC 4665 is similar to the age of the Pleiades. The
  correlation of rotation and X-ray emission levels is consistent with
  that in other young clusters. <P />Among the high-mass stars in IC
  4665, five B stars are detected as X-ray sources. Of these, one is
  a spectroscopic binary while the remaining objects are apparently
  single stars. The level of intrinsic X-ray emission observed in the
  rapidly rotating (v sin i &gt; 200 km s<SUP>-1</SUP>), single B stars
  is consistent with an origin due to shock heating of the ambient
  medium by radiatively driven, rotationally enhanced winds. On the
  basis of these observations and the results for other clusters, we
  argue that observed levels of X-ray emission in high-mass stars of log
  (L<SUB>X</SUB>/L<SUB>bol</SUB>) &gt; -6.0 are likely due to intrinsic
  emission associated with the B star itself rather than emission from
  a late-type secondary. Finally, our results suggest that the initial
  angular momentum distributions and the subsequent evolution of rotation,
  L<SUB>X</SUB>, and (L<SUB>X</SUB>/L<SUB>bol</SUB>) occur in practically
  identical fashions in clusters with ages &lt;~100 Myr.

---------------------------------------------------------
Title: A Joint X-ray and Optical Investigation of the Young Open
    Cluster IC 4665
Authors: Giampapa, M. S.; Prosser, C. F.; Fleming, T. A.
1998ASPC..154.2106G    Altcode: 1998csss...10.2106G
  We summarize the results of a joint ROSAT High Resolution Imager (HRI)
  and optical investigation of the open cluster IC 4665. The ROSAT
  data-set contains detections for 28 stellar sources in the field,
  including 22 cluster members and candidate members spanning the color
  range -0.18 &lt;= (B-V)_o \&lt;= +1.63 (~B3 - M3). Keck HIRES spectra
  have been obtained that yield radial and rotational velocity measures,
  respectively, for faint, low mass candidate members located within
  the field of the ROSAT HRI observation.

---------------------------------------------------------
Title: A Survey of Chromospheric Activity in the Solar-Type Stars
    in M67
Authors: Giampapa, Mark S.
1998saco.conf...65G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Procyon campaign: Observations from Kitt Peak
Authors: Pilachowski, C. A.; Barden, S.; Hill, F.; Harvey, J. W.;
   Keller, C. U.; Giampapa, M. S.
1998IAUS..185..319P    Altcode:
  Time series spectra of the F5IV star Procyon (alpha CMi) were obtained
  at the Kitt Peak National Observatory during a 35-night observing run
  in January-February 1997. The observations were obtained as part of an
  international collaboration to detect and study acoustic oscillations
  in solar-type stars. Spectra covered the wavelength range from 4000
  to 5300 AA , with a resolving power of approximately 3500 (1.3 AA
  resolution). The sampling rate was one observation per minute, and
  the typical S/N ratio per observation is in excess of 1000. At the
  time of writing, we have obtained over 10,000 spectra. The spectra
  will be analyzed to identify any periodic signals due to acoustic
  oscillations in Procyon. In addition to measuring the equivalent widths
  of the three Balmer lines (Kjeldsen et al. 1995) covered by our spectra
  (Hβ, Hγ, and Hdelta) we will also examine the spectra for variations
  in the average metal line strength. Preliminary power spectra will
  be presented.

---------------------------------------------------------
Title: Asteroseismology from equivalent widths: a test of the sun
Authors: Keller, C. U.; Harvey, J. W.; Barden, S. C.; Giampapa, M. S.;
   Hill, F.; Pilachowski, C. A.
1998IAUS..185..375K    Altcode:
  Kjeldsen et al. (1995) reported a probable detection of solar-like,
  low-amplitude, p-mode oscillations of eta Bootes using equivalent
  width measurements from low-resolution spectra of the hydrogen Balmer
  lines. We tested the usefulness of this technique using observations of
  the Sun in integrated light. Despite the very high signal-to-noise ratio
  of the data stretching over six continuous days, no solar oscillation
  signal was found so far in the equivalent width of Hβ. Spatially
  resolved observations of the Hβ equivalent width at solar disk center
  reveal that the oscillation signal is suppressed in the wings of Hβ
  as compared to the continuum. Extrapolation of the oscillation signal
  seen in the spatially resolved data suggests an amplitude of about
  1ppm for integrated light measurements, which is about a factor of
  5 lower than expected from simple theoretical arguments. We explore
  other methods to deduce an oscillation signal from all spectral lines
  simultaneously. cont has: Deng, L. et al.; auths fixed below

---------------------------------------------------------
Title: Rotational Velocities and Chromospheric/Coronal Activity of
    Low-Mass Stars in the Young Open Clusters IC 2391 and IC 2602
Authors: Stauffer, John R.; Hartmann, Lee W.; Prosser, Charles F.;
   Randich, Sofia; Balachandran, Suchitra; Patten, Brian M.; Simon,
   Theodore; Giampapa, Mark
1997ApJ...479..776S    Altcode:
  We have obtained high-resolution, moderate signal-to-noise ratio spectra
  for approximately 80 candidate low-mass members of the nearby, very
  young open clusters IC 2391 and IC 2602. Most of the stars observed
  are confirmed as cluster members based on a combination of photometric
  and spectroscopic criteria. We provide radial velocities, rotational
  velocities, and Hα equivalent widths for these stars. From comparison
  to theoretical pre-main-sequence (PMS) evolutionary isochrones
  from D'Antona and Mazzitelli, we derive an estimated age of the two
  clusters of ~25 Myr. By contrast, the usually quoted upper main-sequence
  turnoff age for the clusters is ~35 Myr. We do not believe that this
  provides evidence for noncoeval star formation within these clusters,
  but rather that the best age estimate for them given the uncertainties
  is ~30 +/- 5 Myr. In principle, the scatter of stars about the PMS
  isochrone provides a measure of the age spread among the low-mass
  stars in these clusters; however, with the data presently available,
  we are able to derive only a relatively uninteresting upper limit for
  an age spread of order 20 Myr. <P />We compare the rotational velocity
  distribution for IC 2391/2602 to that observed for the Pleiades. For
  the G dwarfs in the IC clusters, we resolve rotation in all but one of
  the probable cluster members, and thus except for inclination effects,
  our data provide the complete distribution of rotational velocities for
  solar mass stars on their arrival on the ZAMS. The projected rotational
  velocities (v sin i) of the G dwarfs in the two IC clusters span the
  range from ~8 to ~200 km s<SUP>-1</SUP>. Comparison of the distribution
  of rotational velocities for the G dwarfs of the Pleiades and the IC
  clusters indicates that both the slow and the rapid rotators lose of
  order half their angular momentum during the first ~35 Myr on the main
  sequence if they rotate as solid bodies. <P />The low-mass stars in
  these two clusters exhibit a similar correlation between rotation and
  coronal activity as is found in several other young open clusters. That
  is, there is a large spread in coronal activity for stars with v sin
  i &lt; 25 km s<SUP>-1</SUP>, where we assume there is an intrinsic
  link between increasing rotation and increasing activity superimposed
  upon which are a variety of observational and physical mechanisms that
  act to smear out this relation; above v sin i ~ 25 km s<SUP>-1</SUP>,
  all of the low-mass stars have log (L<SUB>X</SUB>/L<SUB>bol</SUB>) ~
  -3.0, the canonical “saturation” limit. Our measurements of the Hα
  equivalent widths are consistent with a similar relationship holding
  for chromospheric activity. One and possibly two of our spectra for M
  dwarf members of the IC clusters show broad wings for the Hα profile,
  which we attribute to a flare event or to microflares. Since spectra
  of a small sample of late-type M dwarfs in the Pleiades also showed
  similarly broad Hα wings, this suggests that flare frequencies for
  very young M dwarfs may be quite high.

---------------------------------------------------------
Title: Preface
Authors: Jokipii, J. R.; Sonett, C. P.; Giampapa, M. S.
1997cwh..confD..11J    Altcode: 2006mslp.confD..11J
  No abstract at ADS

---------------------------------------------------------
Title: Cosmic Winds and the Heliosphere
Authors: Jokipii, Jack R.; Sonett, Charles P.; Giampapa, Mark S.
1997cwh..book.....J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Cosmic winds and the heliosphere.
Authors: Jokipii, J. R.; Sonett, C. P.; Giampapa, M. S.
1997cwh..conf.....J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Coronae of Low-Mass Dwarf Stars
Authors: Giampapa, M. S.; Rosner, R.; Kashyap, V.; Fleming, T. A.;
   Schmitt, J. H. M. M.; Bookbinder, J. A.
1996ApJ...463..707G    Altcode:
  We report the results of our analysis of pointed X-ray observations
  of nearby dMe and dM stars using the position sensitive proportional
  counter (PSPC) on board the ROSA T satellite (Roentgensatellit). In the
  cases of those M dwarf stars where PSPC pulse-height distributions of
  sufficient quality for spectral fitting were obtained, we derive key
  coronal plasma parameters in order to investigate stellar coronal
  structure in more detail. In particular, we utilize temperatures
  and emission measures inferred for one or more distinct components
  as constraints for the development of semiempirical magnetic loop
  models as representations of the coronae of low-mass stars. The
  consistency of these static models as adequate descriptions of the
  coronae of M dwarfs is then examined. <P />We find that the coronae of
  low-mass dwarfs consist of two distinct thermal components: a "soft"
  component with T ∼ 2-4 x 10<SUP>6</SUP> K and a "hard" component
  with T ∼ 10<SUP>7</SUP> K. We find that the pulse- height spectra
  are systematically fitted better with "depleted" abundances compared to
  solar; the high- temperature emission component on dMe stars appears to
  contribute a systematically larger fraction of the total flux than the
  corresponding component in dM stars; and the high-temperature emission
  component on dMe stars is responsible for most of the observed variation
  in the count rate. <P />We have modeled the observed temperature
  components with hydrostatic coronal loop models, and find that: the
  low-temperature components can be modeled with loops of small size (l
  ≪ R<SUB>*</SUB>) and high pressure (Po ); and the high-temperature
  components require solutions with either small filling factors (
  0.1), large loops (1 &gt; R*), and high base pressure (P<SUB>0</SUB>
  &amp;#8819 P<SUB>0</SUB><SUB>sun</SUB>), or very small filling factors
  (∼0.1), small loops (1 &amp;#8819 R<SUB>*</SUB>), and very high
  pressure (P<SUB>0</SUB> ≫ P<SUB>0</SUB><SUB>sun</SUB>)). Based on
  these observational and model results, we conclude that coronal emission
  in dMe stars can be interpreted as arising from quiescent active regions
  (a quiescent, low-temperature component) and compact flaring structures
  (variable, high- temperature component). <P />Our conclusion that the
  coronal geometry for low-mass dwarf stars is dominated by a combination
  of relatively compact, quiescent loop configurations and an unstable
  flaring component has implications for both stellar dynamo theory and
  for our understanding of stellar angular momentum evolution. With regard
  to rotation in late-type stars, which has a direct bearing on dynamo
  action, we know from observations that the lowest mass stars spin down
  (via magnetic braking) more slowly than the more nearly solar-type
  stars. The compact loops we find for the low-temperature component
  suggests a natural explanation for the observed mass dependence of
  angular momentum evolution in late-type, main-sequence stars.

---------------------------------------------------------
Title: Asteroseismology via equivalent widths - tests on Procyon,
    Eta Bootis, and Alpha Trianguli.
Authors: Harvey, J. W.; Pilachowski, C.; Barden, S.; Giampapa, M.;
   Keller, C. U.; Hill, F.
1996BAAS...28..917H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Asteroseismology via Equivalent Widths -- Tests on Procyon,
    Eta Bootes, and Alpha Triangulum
Authors: Harvey, J.; Pilachowski, C.; Barden, S.; Giampapa, M.;
   Keller, C.; Hill, F.
1996AAS...188.5903H    Altcode: 1996BAAS...28S.917H
  Recently, Kjeldsen et al. reported a probable detection of solar-like
  low-amplitude p-mode oscillations of Eta Bootes using equivalent
  width measurements from low-resolution spectra of the H Balmer
  lines. This technique has the potential to provide stellar oscillation
  measurements good enough to allow the asteroseismic inference of stellar
  structure. Here we report on the preliminary analysis of data from three
  observing runs with the Kitt Peak Coude Feed and 2.1-m telescope in
  November 1995 (Alpha Triangulum), February 1996 (Procyon), and March
  1996 (Eta Bootes). These runs are being used to develop observing
  and data reduction techniques, such as a synchronized timing system
  to maintain evenly spaced temporal samples, a continuous unshuttered
  CCD readout to increase the duty cycle of the observations, and a
  simulation of the probability of a detection as a function of observing
  run length. We observed the region around the H beta, gamma, and delta
  lines with a spectral dispersion of about 0.4 Angstroms per pixel,
  extracted equivalent widths, and performed time series analysis. The
  temporal spectrum of Alpha Triangulum contains a significant peak near
  the theoretical prediction, however, we do not yet know the origin of
  this peak.

---------------------------------------------------------
Title: The Future of High Resolution Spectroscopy at Kitt Peak
    National Observatory
Authors: Barden, S.; Pilachowski, C.; Giampapa, M.
1996AAS...188.3902B    Altcode: 1996BAAS...28..882B
  Many astronomical studies benefit from observations of celestial
  objects at high spectral resolving power. Some of the facilities and
  instrumentation for high dispersion spectroscopy, however, are coming
  under the threat of closure or are reaching their limit of usefulness
  due to the small aperture of the telescopes that feed them. Many of
  the new facilities either don't have sufficient spectral resolution
  or are located at observatories with very restricted access or
  scheduling. KPNO has convened a committee to 1) examine the scientific
  needs of high resolution spectroscopy, 2) evaluate the facilities which
  are available to the general astronomical community, and 3) develop
  and prioritize instrumentation goals for future KPNO facilities. The
  Committee will also consider policies for scheduling KPNO telescopes
  to maximize scientific return from high resolution spectrographs,
  including possible changes to the TAC process and visitor and queue
  observing modes. We desire community input and will formulate our
  report and recommendations over the next seven months.

---------------------------------------------------------
Title: Advances in solar-stellar physics: optical and infrared studies
Authors: Giampapa, M. S.
1996ASPC..109...11G    Altcode: 1996csss....9...11G
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Structwre in M Dwarf Stars
Authors: Giampapa, M. S.; Rosner, R.; Kashyap, V.; Fleming, T. A.;
   Schmitt, J. H. M. M.; Bookbinder, J. A.
1996mpsa.conf...81G    Altcode: 1996IAUCo.153...81G
  No abstract at ADS

---------------------------------------------------------
Title: The chromospheric activity of the many "suns" in M67.
Authors: Giampapa, M. S.; Baliunas, S. L.; Radick, R. R.
1996BAAS...28.1197G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Stellar Activity at the End of the Main Sequence: GHRS
    Observations of the M8 Ve Star VB 10
Authors: Linsky, Jeffrey L.; Wood, Brian E.; Brown, Alexander;
   Giampapa, Mark S.; Ambruster, Carol
1995ApJ...455..670L    Altcode:
  We present Goddard High Resolution Spectrograph observations of the M8
  Ve star VB 10 (= Gl 752B), located very near the end of the stellar
  main sequence, and its dM3.5 binary companion Gl 752A. These coeval
  stars provide a test bed for studying whether the outer atmospheres of
  stars respond to changes in internal structure as stars become fully
  convective near mass 0.3 M<SUB>sun</SUB> (about spectral type MS), where
  the nature of the stellar magnetic dynamo presumably changes, and near
  the transition from red to brown dwarfs near mass 0.08 M<SUB>sun</SUB>
  (about spectral type M9), when hydrogen burning ceases at the end of
  the main sequence. We obtain upper limits for the quiescent emission
  of VB 10 but observe a transition region spectrum during a large flare,
  which indicates that some type of magnetic dynamo must be present. Two
  indirect lines of evidence scaling from the observed X-ray emission and
  scaling from a time-resolved flare on AD Le suggest that the fraction of
  the stellar bolometric luminosity that heats the transition region of
  VB 10 outside of obvious flares is comparable to, or larger than, that
  for Gl 752A. This suggests an increase in the magnetic heating rates,
  as measured by L<SUB>line</SUB>/L<SUB>bol</SUB> ratios, across the
  radiative/convective core boundary and as stars approach the red/brown
  dwarf boundary. These results provide new constraints for dynamo models
  and models of coronal and transition-region heating in late-type stars.

---------------------------------------------------------
Title: The Photometric Method for the Detection of Extrasolar Planets
Authors: Giampapa, M. S.; Craine, E. R.; Hott, D. A.
1995AAS...187.7017G    Altcode: 1995BAAS...27.1382G
  We offer further perspectives on the application of the photometric
  technique to the search for extrasolar planets. The principal
  obstacles to this approach include (1) the ambiguous interpretation
  of the photometric signature of a possible transit event arising
  from the potential for confusion with stellar activity, and (2) the
  observational intensity of the search technique. We emphasize that
  the former issue can be addressed through multiband observations
  combined with considerations of the characteristic time scales of
  forms of stellar activity compared to that of a transit event. In the
  case of the latter concern, the advent of modern, automated telescope
  technologies offers the realistic prospect of meeting the demanding
  observational requirements of this approach. We find that joint
  visual and near infrared observations are necessary to immediately
  distinguish between, for example, a planetary transit and a cool spot
  on the stellar surface. However, these observations by themselves
  do not appear sufficient to distinguish between a brown dwarf and a
  Jovian-size planetary companion of a dwarf M star. In such cases,
  other complementary observations will be necessary. We develop a
  computer simulation to estimate the average number of transits per
  year that would be presented for a stellar sample characterized by
  realistic properties in terms of spectral type distribution, effective
  temperatures, masses, and radii. A simple thermal model is adopted
  to estimate star-planet separations. The simulation suggests that the
  frequency of transit events will be dominated by M dwarf systems. This
  is due to the large number of these objects combined with the relative
  proximity to these cool stars within which planetary formation can
  occur according to current models.

---------------------------------------------------------
Title: Comments on the photometric method for the detection of
    extrasolar planets.
Authors: Giampapa, Mark S.; Craine, Eric R.; Hott, Douglas A.
1995Icar..118..199G    Altcode:
  We offer further perspectives on the application of the photometric
  technique to the search for extrasolar planets. The principal
  obstacles to this approach include (1) the ambiguous interpretation
  of the photometric signature of a possible transit event arising
  from the potential for confusion with stellar activity and (2) the
  observational intensity of the search technique. We emphasize that the
  former issue can be addressed through multiband observations combined
  with consideration of the characteristic time scales of forms of
  stellar activity compared to the time scale of a transit event. In the
  case of the latter concern, the advent of modern, automated telescope
  technologies offers the realistic prospect of meeting the demanding
  observational requirements of this approach. <P />We find that joint
  visual and near infrared observations are necessary to immediately
  distinguish between, for example, a planetary transit and a cool spot
  on the stellar surface. However, these observations by themselves
  do not appear sufficient to distinguish between a brown dwarf and
  a jovian-size planetary companion of a dwarf M star. In such cases,
  other complementary observations will be necessary. We developed a
  computer simulation to estimate the average number of transits per
  year that would be presented for a stellar sample characterized by
  realistic properties in terms of spectral type distribution, effective
  temperatures, masses, and radii. A simple thermal model is adopted
  to estimate star-planet separations. The simulation suggests that the
  frequency of transit events will be dominated by M dwarf systems. This
  is due to the large number of these objects combined with the relative
  proximity to these cool stars within which planetary formation can
  occur according to current models.

---------------------------------------------------------
Title: The X-Ray View of the Low-Mass Stars in the Solar Neighborhood
Authors: Schmitt, Juergen H. M. M.; Fleming, Thomas A.; Giampapa,
   Mark S.
1995ApJ...450..392S    Altcode:
  We present the results of a complete and sensitive X-ray survey
  of all known stars of spectral type K and M in the immediate solar
  vicinity with distances less than 7 pc. The X-ray data were obtained
  primarily from the ROSA T all-sky survey (RASS); those program stars
  not detected in the RASS data were subsequently studied with the ROSAT
  pointed observation program. These new X-ray observations resulted
  in a detection rate of almost 94% for all K and M stars within 6
  pc around the Sun, and 87% for K and M dwarfs within 7 pc around
  the Sun. The resulting X-ray luminosity distribution function can be
  well described by a log-normal distribution; the largest and smallest
  X-ray luminosities from our sample stars differ by almost four orders
  of magnitude. We show the existence of a correlation between total
  emitted X-ray luminosity and spectral hardness, such that more luminous
  objects tend to have larger spectral hardness, thus implying higher
  coronal temperatures. A comparison with Einstein data shows the lack of
  significant variability in excess of a factor of 2 in our sample stars.

---------------------------------------------------------
Title: Correlations of Coronal X-Ray Emission with Activity, Mass,
    and Age of the Nearby K and M Dwarfs
Authors: Fleming, Thomas A.; Schmitt, Juergen H. M. M.; Giampapa,
   Mark S.
1995ApJ...450..401F    Altcode:
  Using the ROSAT telescope, we have detected X-ray emission from 87%
  of all known K and M dwarfs within 7 pc of the Sun. Analysis of this
  volume-limited sample of K and M dwarfs reveals no evidence for a
  decrease in coronal heating efficiency (as measured by L<SUB>x</SUB>/L
  <SUB>bol</SUB>) among the lowest mass, presumably fully convective,
  late-M dwarfs. Furthermore, our results indicate that those stars which
  exhibit little chromospheric activity (i.e., dM and dK stars) do indeed
  have cooler and weaker coronae than the more active dMe stars. While
  we also see a correlation between coronal temperature/strength and
  metallicity (and presumably age), no such correlation is seen with
  kinematic class. The latter result leads us to suggest that kinematic
  class is a poor age indicator for the nearby stars.

---------------------------------------------------------
Title: Helium in the Spectrum of the Sun and of Solar-Type Stars
Authors: Andretta, V.; Giampapa, M. S.; Jones, H. P.
1995IrAJ...22..177A    Altcode:
  We present results from detailed non-LTE radiative transfer calculations
  of the He I spectrum in the Sun. Using an extended grid of model
  chromospheres, we explore the relative importance of, respectively,
  the coronal XUV illumination and the thermal structure of the lower
  transition region. With reference to the He I lambda 587.6 and lambda
  1083.0 triplet lines, we point out some implications for the study of
  activity in solar-type stars.

---------------------------------------------------------
Title: The Coronae of Quiescent M Dwarf Stars
Authors: Giampapa, Mark S.
1995euve.prop....6G    Altcode:
  We propose to obtain SW and MW EUVE spectrometer observations of
  the quiescent M dwarf GL 205 (dM1). This non-dMe star in the solar
  neighborhood is an X-ray source as seen with the ROSAT PSPC. The
  infrared colors of GL 205 suggest that its photospheric abundances are
  solar-like. Our proposed EUVE data will be used to determine if the
  coronal structure is characterized by only two dominant components,
  as suggested by our analysis of X-ray data for dM stars, or if dwarf M
  coronae actually consist of multiple components with a distribution of
  maximum loop temperatures. This will yield valuable inputs for models
  of coronal heating and angular momentum evolution. A comparison between
  the results for a quiet non-dMe star with those for active dMe stars
  (available in the EUVE archives) will reveal if the difference in
  their emission levels arises from a fundamental difference in coronal
  structure or if it is merely a difference in scale (e.g., filling
  factors of active regions). In summary, the EUVE data for a dM star
  will be an important comparison for active dMe stars.

---------------------------------------------------------
Title: A Method for Estimating the Fractional Area Coverage of Active
    Regions on Dwarf F and G Stars
Authors: Andretta, Vincenzo; Giampapa, Mark S.
1995ApJ...439..405A    Altcode:
  The D<SUB>3</SUB> (lambda 5876) and lambda 10830 lines arising from
  triplet levels in neutral helium appear in absorption in active
  (plage) regions on the Sun and, by implication, in the active
  regions on Sun-like (F-early K) stars. These features either do not
  occur, or appear only very weakly, in the quite solar (or stellar)
  photosphere. Hence, these diagnostics are ideal tracers of magnetic
  regions outside of cool spots. The appearance of D<SUB>3</SUB> and
  lambda 10830 in absorption immediately suggests that these lines can
  be utilized to infer the fractional area coverage, or filling factor,
  of active region on stellar surfaces if their intrinsic absorption
  strengths in these regions are known. In particular, a meaningful
  lower limit to the active filling factor can be deduced if the maximum
  absorption equivalent width (W<SUB>max</SUB>) in D<SUB>3</SUB> or
  lambda 10830 as either appears in stellar analogs of solar plages
  can be estimated. We develop this approach by constructing a grid
  of model chromospheres based on the VAL C model of the quiet solar
  chromosphere. This thermal structure is superposed on published models
  for F and G dwarf photospheres. We solve for the non-LTE ionization of
  hydrogen to infer chromospheric electron densities. We then perform
  a multilevel, non-LTE computation of the helium triplet lines in the
  sequence of model chromospheres, taking into account the potential
  effects of coronal XUV back radiation on the line formation. We
  conservatively estimate that W<SUB>max</SUB> approximately = 100-150
  mA for D<SUB>3</SUB> in both F and G dwarfs. The implied lower limits
  to the filling factor of plagelike regions can be approximately 20%
  among active solar-type stars. We extend this approach by investigating
  a method by which the actual filling factor can be deduced through
  a study of the joint response of D<SUB>3</SUB> and lambda 10830 to
  chromospheric nonradiative heating. We emphasize that our filling factor
  estimates indicate the area coverage at the height of formation of
  the helium triplet lines in the active chromosphere. Because of field
  line spreading with height, filling factors based on chromospheric
  lines are expected to exceed estimates based on purely photospheric
  lines. Finally, we discuss the relative importance of collisional
  and photoionization processes in the formation of these important
  diagnostics.

---------------------------------------------------------
Title: Radial Velocities of Very Low Mass Stars and Candidate Brown
    Dwarf Members of the Hyades and Pleiades. II.
Authors: Stauffer, John R.; Liebert, James; Giampapa, Mark
1995AJ....109..298S    Altcode:
  We have determined H alpha equivalent widths and radial velocities
  with 1 sigma accuracies of approximately 5 km/s for approximately 20
  candidate very low mass members of the Pleiades cluster and for a few
  proposed very low mass members of the Hyades. Most of the Pleiades
  targets were selected from the recent Hambly, Hawkins, and Jameson
  proper motion survey, where they were identified as probable Pleiades
  brown dwarfs with an age spread from 3 to 70 Myr. Our spectroscopic
  data and a reinterpretation of the photometric data confirm that these
  objects are indeed likely Pleiades members; however, we believe that
  they more likely have masses slightly above the hydrogen burning mass
  limit and that there is no firm evidence for an age spread amongst
  these stars. All of the very low mass Pleiades and Hyades members show
  H alpha in emission. However, the ratio of H alpha flux to biometric
  flux in the Pleiades shows a maximum near M<SUB>Bol</SUB> approximately
  equal to 9.5 (M approximately equal to 0.3 solar mass) and a sharp
  decrease to lower masses. This break occurs at the approximate mass
  where low mass stars are expected to become fully convective, and it
  is tempting to assume that the decrease in H alpha flux is caused by
  some change in the behavior of stellar dynamos at this mass. We do not
  see a similar break in activity at this mass in the Hyades. We discuss
  possible evolutionary explanations for this difference in the H alpha
  activity between the two clusters.

---------------------------------------------------------
Title: The β Pictoris phenomenon among young stars. I. The case of
    the Herbig AE star UX Orionis.
Authors: Grinin, V. P.; The, P. S.; de Winter, D.; Giampapa, M.;
   Rostopchina, A. N.; Tambovtseva, L. V.; van den Ancker, M. E.
1994A&A...292..165G    Altcode:
  In this paper we present the first results of the study of very
  young stars having non-periodic Algol type brightness minima. It is
  based on cooperative observations between the Crimean Astrophysical
  Observatory (CAO), the European Southern Observatory (ESO) and
  the National Solar Observatory (NSO). In August-September, 1992,
  a very deep ({DELTA}V=2.5mag), long lasting minimum of the light of
  the isolated Herbig Ae star UX Ori occurred. At this event the star
  was observed photometrically (UBVRI) and polarimetrically at the
  CAO, and spectroscopically (high resolution: Hα and NaiD) at the
  ESO. The spectroscopic observations were continued at the NSO with
  the McMath solar/stellar telescope in October-December, 1992, when
  the star returned to maximum brightness and again at the ESO in July
  and October, 1993, when the star was bright. The main results of our
  observations can be briefly summarized as follows: 1) The photometric
  and polarimetric results are in agreement with the model according
  to which UX Ori is surrounded by an edge-on circumstellar disk-like
  envelope, and its variability is caused by variable obscuration of
  the star by opaque circumstellar dust clouds. 2) The double-peaked
  Hα profile observed at maximum light changed to single-peaked at
  deep minimum; obscuration of a part of the circumstellar gas by an
  optically thick dust cloud is causing this variation, 3) The inverse P
  Cygni profiles and variable redshifted absorption components have been
  observed in the NaiD lines indicating the infall of cool gas onto the
  star. We believe that, such as in the case of the star β Pictoris,
  violent comet-like activity takes place in the young protoplanetary
  disk of UX Ori which causes the observed variability.

---------------------------------------------------------
Title: Coronal Loop Model Atmospheres for Low Mass Stars
Authors: Giampapa, M.; Rosner, R.; Kashyap, V.; Fleming, T.; Schmitt,
   J.; Bookbinder, J.
1994AAS...185.9807G    Altcode: 1994BAAS...26Q1480G
  We have constructed semi-empirical loop models that best fit key
  coronal parameters derived from ROSAT PSPC observations of selected
  low mass stars. The X-ray pulse-height distributions are represented
  by two dominant components. These include a soft component that is
  characterized by compact loop configurations with loop lengths that are
  one or more orders of magnitude smaller than the stellar radius. By
  contrast, two types of stable solutions can be found for the hard
  component, namely very long loops (much larger than a pressure scale
  height) with large filling factors, and very compact loops with very
  small filling factors. The “long" solutions are physically excluded
  since they violate stability criteria. We identify the “small"
  solutions with compact loop flares. The implications of these results
  for coronal structure and angular momentum evolution in low mass dwarfs
  will be discussed.

---------------------------------------------------------
Title: A Radial Velocity Survey of the Open Cluster IC 4665
Authors: Prosser, Charles F.; Giampapa, Mark S.
1994AJ....108..964P    Altcode:
  A radial velocity survey of the open cluster IC 4665 is reported for a
  group of candidate members previously identified on the basis of proper
  motion and photometry. Of those candidates observed, 20 out of 42 have
  radial velocities consistent with membership; these cluster members
  populate the F5-K0 dwarf region and represent the first relatively
  conclusive membership determinations for such solar-type stars in IC
  4665. Three new spectroscopic binary members of the cluster have been
  identified. Rotational velocities have also been derived; the v sin i
  distribution among IC 4665 members reveals that most apparent G dwarf
  members of IC 4665 are seen to exhibit substantial rotation (v sin i
  greater than 10 km/s). When compared to evolutionary isochrones, the
  current list of intermediate-mass members appears to support earlier
  suggestions that IC 4665 has an age comparable to the Pleiades.

---------------------------------------------------------
Title: Radial Velocities of Very Low mass Stars and Candidate Brown
    Dwarf Members of the Hyades and Pleiades
Authors: Stauffer, John R.; Liebert, James; Giampapa, Mark; Macintosh,
   Bruce; Reid, Neill; Hamilton, Donald
1994AJ....108..160S    Altcode:
  We have determined H alpha equivalent widths and radial velocities
  with 1 sigma accuracies of approximately 5 km s<SUP>-1</SUP> for
  approximately 20 candidate very low mass members of the Hyades and
  Pleiades clusters. The radial velocities for the Hyades sample suggest
  that nearly all of these stars are indeed highly probable members of the
  Hyades. The faintest stars in the Hyades sample have masses of order 0.1
  solar mass. We also obtained radial velocities for four candidate very
  low mass members of the Pleiades and two objects that are candidate BD
  Pleiads. All of these stars have apparent V magnitudes fainter than the
  Hyades stars we observed, and the resultant radial velocity accuracy
  is worse. We believe that the three brighter stars are indeed likely
  very low mass stellar members of the Pleiades, whereas the status of
  the two brown dwarf candidates is uncertain. The Hyades stars we have
  observed and the three Pleiades very low mass stars are the lowest
  mass members of any open cluster whose membership has been confirmed by
  radial velocities and whose chromospheric activity has been measured. We
  see no change in chromospheric activity at the boundary where stars
  are expected to become fully convective (M approximately equals 0.3
  solar mass) in either cluster. In the Pleiades, however, there may be
  a decrease in chromospheric activity for stars with (V-I)<SUB>K</SUB>
  greater than 3.5 (M less than or equal to 0.1 solar mass).

---------------------------------------------------------
Title: Upgrade of the McMath-Pierce stellar spectrograph
Authors: Giampapa, Mark S.; Simmons, Jorge E.; Jaksha, David B.;
   Perkins, E. L.
1994SPIE.2198..302G    Altcode:
  We discuss a design for an echelle spectrograph based on three prisms
  as the cross-dispersing optical elements. Since high throughput in our
  particular system is achieved using an image slicer, obtaining adequate
  order separation is a challenge. We find that the design described
  herein yields good efficiencies throughout the visible wavelength
  range while also providing adequate order separation in the red.

---------------------------------------------------------
Title: Extrasolar planetary search using a network of automated
    telescopes
Authors: Craine, Eric R.; Giampapa, Mark S.; Hott, Douglas A.
1994SPIE.2198.1398C    Altcode:
  Conventional search techniques for extrasolar planets have not yielded
  indisputable evidence of such planets. The small sample sizes of
  previously employed searches ensure that a null result provides little
  or no information on the numbers or distributions of such planets. The
  photometric technique, wherein monitoring is performed to detect
  light curves distinctively characteristic of a planetary transit, has
  been a tantalizing prospect, but has always been rejected because of
  its observational intensity. Moderate aperture (0.5-1.0 m) automated
  telescopes and multi- color CCD imaging arrays with image recognition
  software form the instrumental foundation for a global network to
  conduct such a search. Catalogs of cool dwarf stars provide a program
  star list with the advantages of orbital geometries and photometric
  properties enabling detection of planetary transits with a network
  of modes proportions. We reaffirm the viability of the photometric
  approach and outline the methodology of the search. Computer modelling
  of various strategies of conducting such a planetary search has been
  undertaken and we outline the resulting network configurations and
  observing strategies suggested by this effort.

---------------------------------------------------------
Title: Lithium in RS Canum Venaticorum binaries and related
    chromospherically active stars. III. Northern RS CVn systems.
Authors: Randich, S.; Giampapa, M. S.; Pallavicini, R.
1994A&A...283..893R    Altcode:
  High-resolution spectra of Northern RS CVn binaries obtained at the
  NSO-Kitt Peak are analyzed with a spectrum synthesis code to derive Li
  abundances, metallicities and rotation rates. The data are then combined
  with previous observations of Southern RS CVn binaries obtained at ESO,
  yielding a total sample of 67 individual components in 54 catalogued
  RS CVn binaries. We confirm the presence of substantial amounts of
  Li in many chromospherically active stars in the sample, with no
  significant difference between the Northern and Southern samples. We
  specifically address the question of whether these relatively high
  Li abundances are due to enhanced chromospheric activity or rather
  are a consequence of evolutionary history in stars of sufficiently
  high mass. We investigate the dependence of Li abundance on mass by
  using mass determinations in binary systems as well as comparison
  with theoretical evolutionary tracks. We show that while Li abundances
  in subgiants and in the warmer stars of the sample may be consistent
  with a dependence on mass, there is no clear indication in the data
  that the cooler giants with larger Li abundances are also the more
  massive ones. Uncertainties in the comparison with evolutionary tracks
  may partially be responsible for this negative result. Alternatively,
  Li depletion and dilution in evolved stars may be more complex than
  predicted by standard evolutionary models.

---------------------------------------------------------
Title: The Beta Pictoris phenomenon among young stars. I. The case
    of Herbig AC star UX ORI
Authors: Grinin, V. P.; Rostopchina, A. N.; de Winter, D.; The, P. S.;
   van den Ancker, V.; Giampapa, M.; Tambovtseva, L. V.
1994ASPC...62..130G    Altcode: 1994nesh.conf..130G
  No abstract at ADS

---------------------------------------------------------
Title: Perspectives on the Relationship between Activity and
    Fundamental Stellar Parameters (Invited Review)
Authors: Giampapa, M. S.
1994ASPC...64..509G    Altcode: 1994csss....8..509G
  No abstract at ADS

---------------------------------------------------------
Title: The X-Ray Luminosity Function of the Nearby K and M Dwarfs:
    Results from ROSAT
Authors: Fleming, Thomas A.; Schmitt, J. H. M. M.; Giampapa, Mark S.
1994ASPC...64...77F    Altcode: 1994csss....8...77F
  No abstract at ADS

---------------------------------------------------------
Title: The Coronae of Low Mass Dwarf Stars
Authors: Giampapa, Mark S.
1994euve.prop...63G    Altcode:
  We propose to obtain SW and MW EUVE spectrometer observations of
  selected M dwarfs for which we have ROSAT PSPC X-ray pulse-height
  distributions. The EUVE data will be used to determine if the coronal
  structure is characterized by only two dominant components, as suggested
  by our analysis of the X-ray data, or if dwarf M coronae actually
  consist of multiple components with a distribution of maximum loop
  temperatures. We will use the potential constraints available with the
  density diagnostics in the EUV spectra to improve the determination
  of loop morphologies that thus far have been based solely on X-ray
  photometric data. This will yield valuable inputs for models of coronal
  heating (through the determination of heat dissipation scales) and
  models of angular momentum evolution (via magnetic braking) in low
  mass stars. A comparison of the results for the quiet dM star and
  the active dMe stars will reveal if the difference in their emission
  levels arises from a fundamental difference in coronal structure
  or if it is merely a difference in scale (e.g., filling factors of
  active regions). Finally, an inter-comparison of the results for the
  dMe stars in our program may reveal whether dynamo-related properties
  change across the boundary between partial and full interior convection.

---------------------------------------------------------
Title: The Relationship Between Radiative and Magnetic Fluxes on
    Three Active Solar-type Dwarfs
Authors: Linsky, J. L.; Andrulis, C.; Saar, S. H.; Ayres, T. R.;
   Giampapa, M. S.
1994ASPC...64..438L    Altcode: 1994csss....8..438L
  We present some preliminary results from our coordinated campaign of
  IUE and McMath Telescope magnetic field measurements of three active
  solar-type dwarf stars: 59 Vir, xi Boo A, and HD 131511. We observed
  the three stars nearly every day from May 9 to May 25, 1993, covering
  between 1 and 3 rotations. We explore the functional and spatial
  relationship between magnetic and radiative fluxes.

---------------------------------------------------------
Title: A Synoptic Study of H alpha Line Profile Variability in the
    T Tauri Star SU Aurigae
Authors: Giampapa, Mark S.; Basri, Gibor S.; Johns, Christopher M.;
   Imhoff, Catherine
1993ApJS...89..321G    Altcode:
  We present a catalog of 106 high spectral resolution observations of the
  H-alpha line profile in the T Tauri star SU Aurigae, obtained during
  the period from 1986 October through 1990 November. The spectra were
  acquired during joint synoptic programs to observe selected T Tauri
  stars using the Hamilton Echelle Spectrometer of the Lick Observatory
  and the solar-stellar spectrograph at the McMath telescope of the
  National Solar Observatory on Kitt Peak. A restricted set of Mg II h
  and k line profiles was also obtained in a coordinated program involving
  the International Ultraviolet Explorer (IUE) satellite observatory and
  the McMath solar-stellar facility. Striking variability is evident on
  a nightly basis. A key result is that the relative intensity in the
  blue wing of H-alpha spanning a range of velocities bear -150 km/s is
  modulated at a period of 2.98 +/- 0.4 days. We identify the 2.98 day
  period with the rotation period of the star. We also find that the
  occurrence of the periodic modulation of the mass outflow is episodic
  and most evident during a 2 week sequence of nightly observations. We
  find two other intervals where the periodic spectroscopic variability
  is likely present, although at a lower level of significance at a
  lower level of significance. The variability is otherwise stochastic in
  nature. The Mg II resonance lines exhibit clear variability that is most
  pronounced in the blue wing of the k line. A comparison of the Mg II k
  line profile with H-alpha profiles obtained nearly simultaneous yields
  no apparent correlation between the variable features in each line. The
  profile shapes of the Mg II h and k lines are generally indicative
  of formation in a wind. An analysis of the principal features that
  appear in the H-alpha profile set suggests that the line is composed of
  contributions from an enhanced chromosphere; a relatively slow moving,
  dense, optically thick component of a stellar wind formed relatively
  close to the star; and an optically thin, high-velocity, expanding
  stellar wind located further away from the star. An investigation of
  possible correlations among the principal features in the series of
  H-alpha profiles suggests that as the density in the wind increases,
  the wind may become more unstable to large turbulence. This may lead to
  a reduction in the wind bulk velocity, thus regulating the mass-loss
  rate. We also find that the position of the main absorption feature
  which is always present in the H-alpha profiles is not correlated
  with its depth, indicating that optical depth and wind velocity are
  not correlated in the denser portions of the wind.

---------------------------------------------------------
Title: The Structure of the Coronae of dMe and dM Stars
Authors: Giampapa, M. S.; Schmitt, J. H. M. M.; Fleming, T. A.
1993AAS...183.1507G    Altcode: 1993BAAS...25.1314G
  We discuss results obtained from preliminary coronal loop model
  atmospheres developed on the basis of x-ray pulse-height spectra
  obtained with the ROSAT PSPC. The limited sample is comprised of both
  active dMe stars and quiescent dM stars. An intercomparison of the
  inferred coronal loop parameters for the active and the relatively quiet
  objects will be presented. As reported earlier (Giampapa et al. 1993;
  BAAS, 25, 824), two-temperature fits are required to adequately
  represent the x-ray properties of the dMe stars. In the case of the
  non-dMe stars, the coronal emission measure is dominated by a single,
  relatively soft component. Preliminary estimates of densities, filling
  factors and loop lengths that characterize these separate components
  which define the coronae of low mass dwarf stars will be discussed.

---------------------------------------------------------
Title: Lithium and chromospheric activity in the Alpha Persei cluster.
Authors: Stauffer, John R.; Prosser, Charles F.; Giampapa, Mark S.;
   Soderblom, Mark S.; Simon, Theodore
1993AJ....106..229S    Altcode:
  We have obtained high resolution spectra of a set of proposed members
  of the Alpha Persei open cluster which had previously been shown to
  have anomalously low lithium abundances. We have used the new spectra
  to derive Ca II emission strengths, radial velocities, and reddening
  estimates in order to assess whether these stars truly are members
  of the Alpha Per cluster. We conclude that most of the weak lithium
  stars are indeed bonafide cluster members, and thus the problem of
  explaining their anomalous lithium abundances remains. We have also
  obtained spectra for another sample of stars for which the previous
  membership data were relatively limited. Most of these stars do not
  appear to be members of the cluster.

---------------------------------------------------------
Title: Active Region Area Coverages on Solar-Type Stars
Authors: Giampapa, M. S.; Andretta, V.
1993BAAS...25.1216G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Stellar Coronae at the End of the Main Sequence: A ROSAT
    Survey of the Late M Dwarfs
Authors: Fleming, Thomas A.; Giampapa, Mark S.; Schmitt, J. H. M. M.;
   Bookbinder, Jay A.
1993ApJ...410..387F    Altcode:
  We present X-ray data, both detections and upper limits, from the ROSAT
  all-sky survey for most known M dwarfs later than type M5, as well as
  from selected ROSAT pointed observations of some of these stars. We
  compare these data with similar data for early M dwarfs in an attempt
  to probe the nature of the magnetic dynamo and coronal heating mechanism
  for the very late M dwarfs, which are presumably totally convective. Our
  results indicate that late M dwarfs can have coronae which are just
  as active as those for the early M dwarfs and that coronal heating
  efficiency for 'saturated' stars does not drop at spectral type M6.

---------------------------------------------------------
Title: Coronal Structure of Late M Dwarf Stars
Authors: Giampapa, M. S.; Fleming, T. A.; Schmitt, J. H. M. M.
1993AAS...182.2205G    Altcode: 1993BAAS...25R.824G
  We present preliminary results of the analysis of x-ray pulse-height
  spectra of very late dwarf M stars as obtained with the ROSAT
  PSPC. The majority of the data are derived from a program of pointed
  observations. The limited sample is comprised of both active dMe
  stars and quiescent dM stars. The basic cornal properties are derived
  and compared among the dMe and dM stars in the sample. We find that
  two-temperature fits are required to account for the x-ray emission of
  dMe stars while single-temperature fits appear to adequately represent
  the x-ray properties of the non-dMe objects. In addition, we estimate
  emission measures and coronal loop parameters. The implications for
  coronal structure will be discussed. In particular, we suggest on the
  basis of these preliminary results that the coronae of low mass dwarfs
  are highly geometrically extended relative to the stellar radius. This
  may account for both the high absolute values of L_x and the high
  relative values, i.e., L_x /L<SUB>bol</SUB> , that characterize the
  x-ray emission levels of the dMe stars as compared to that of more
  nearly solar-type stars.

---------------------------------------------------------
Title: Astronomy with the Deep UV Explorer observatory.
Authors: Ferguson, D. H.; Giampapa, M. S.
1993uxrs.conf..309F    Altcode: 1993uxsa.conf..309F
  Recent advances in control systems and sensors allow construction of
  an inexpensive yet high-performance orbiting observatory to collect
  data at ultraviolet wavelengths between 1150 Å and 3000 Å. The Deep
  Ultraviolet Explorer satellite (DUVE) will obtain all-sky imagery at
  various broad band wavelengths, high-resolution images, and spectra
  across the UV region. The DUVE program offers substantial performance
  advantages over current space-based observatories.

---------------------------------------------------------
Title: Stellar coronae at the end of the main sequence: A ROSAT
    survey of the late M dwarfs
Authors: Fleming, T. A.; Giampapa, M. S.; Schmitt, J. H. M. M.;
   Bookbinder, J. A.
1993STIN...9419794F    Altcode:
  X-ray data, both detections and upper limits, from the Rosat
  all sky survey for most known M dwarfs later than type M5 are
  presented. Selected Rosat pointed observations of some of these stars
  are included. These data are compared to similar data for early M dwarfs
  in an attempt to probe the nature of the magnetic dynamo and coronal
  heating mechanism for the very late M dwarfs, which are presumably
  totally convective. The results indicate that late M dwarfs can have
  coronae which are just as active as those for the early M dwarfs and
  that coronal heating efficiency for 'saturated' stars does not drop
  at spectral type M6.

---------------------------------------------------------
Title: Next generation ultraviolet astronomy with the Deep Ultraviolet
    Explorer observatory
Authors: Ferguson, Donald H.; Giampapa, Mark S.
1992SPIE.1697..274F    Altcode:
  The Deep Ultraviolet Explorer (DUVE) satellite, which is a space-based
  observatory providing all-sky imagery and high-resolution spectroscopy
  at wavelengths between 1150 and 3000 A, is discussed. Sky coverage,
  resolution, and sensitivity of DUVE are each equal to or better than
  available on existing spacecraft. Recent advances in controls, sensors,
  and telescope lightweighting coupled with space-qualified designs
  combine to make the DUVE project affordable within the guidelines of
  the Medium Explorer-class mission scenario.

---------------------------------------------------------
Title: Science with GNAT: An Extra-Solar System Planetary Search
Authors: Craine, E. R.; Giampapa, M. S.
1992AAS...181.5702C    Altcode: 1992BAAS...24R1214C
  No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic and Photometric Observations of a Five-Magnitude
    Flare Event on UV CETI
Authors: Eason, Erik L. E.; Giampapa, M. S.; Radick, R. R.; Worden,
   S. P.; Hege, E. K.
1992AJ....104.1161E    Altcode:
  Optical observations of a 5-mag flare in the U band on UV Ceti (dM5.6e)
  at both spectral and temporal resolutions are presented. A strong
  violet continuum which cannot be reproduced solely with a thermal
  bremsstrahlung spectrum is seen. The energy emitted by the flare in the
  U band is about 5.0 x 10 exp 31 ergs. The corresponding total flare
  energy in white light is estimated to be 1.2 x 10 exp 32 ergs. This
  estimate, combined with the 700-s duration of the U-band event, yields
  an average white-light flare luminosity which is about 3 percent of
  the quiescent stellar bolometric luminosity. Strong H-alpha wings
  appeared after the impulsive phase. A discernible central reversal
  is present in both the quiescent H-alpha profile and, significantly,
  in the flare profile following the impulsive phase. It is suggested
  that the site of H-alpha flare emission is not necessarily associated
  with a compact, high pressure region. The flare-enhanced line emission
  arises from large flare volumes that are, in turn, a distinguishing
  feature of stellar flares of this magnitude.

---------------------------------------------------------
Title: Book-Review - the Sun in Time
Authors: Sonett, C. P.; Giampapa, M. S.; Matthews, M. S.
1992SciAm.266f.130S    Altcode: 1992SciAm.266..130S
  No abstract at ADS

---------------------------------------------------------
Title: Mg II Line Profiles in the T Tauri Stars
Authors: Imhoff, C. L.; Giampapa, M. S.; Basri, G.
1992AAS...180.4310I    Altcode: 1992BAAS...24..798I
  No abstract at ADS

---------------------------------------------------------
Title: Using Helium Lines as a Probe for Estimating Surface Filling
    Factors on Sun-Like Stars
Authors: Andretta, V.; Giampapa, M. S.
1992ASPC...26..552A    Altcode: 1992csss....7..552A
  No abstract at ADS

---------------------------------------------------------
Title: Chromospheric Activity; Kinematics of Very Low Mass M Dwarfs
Authors: Liebert, J.; Saffer, R. A.; Norsworthy, J.; Giampapa, M. S.;
   Stauffer, J. R.
1992ASPC...26..282L    Altcode: 1992csss....7..282L
  No abstract at ADS

---------------------------------------------------------
Title: Synoptic Studies of the T Tauri Star SU AUR
Authors: Johns, C. M.; Basri, G. S.; Giampapa, M. S.; Defonso, E.
1992ASPC...26..441J    Altcode: 1992csss....7..441J
  No abstract at ADS

---------------------------------------------------------
Title: Cool stars, stellar systems, and the sun : seventh Cambridge
    workshop
Authors: Giampapa, Mark S.; Bookbinder, Jay A.
1992ASPC...26.....G    Altcode: 1992csss....7.....G
  Bibliographic codes for individual papers begin with "1992csss....7".

---------------------------------------------------------
Title: Lithium in RS CVn binaries and related chromospherically
    active stars. I.Observational results.
Authors: Pallavicini, R.; Randich, S.; Giampapa, M. S.
1992A&A...253..185P    Altcode:
  The present survey of the Li I 6708 A line in a sample of spectral type
  G and K stars with luminosity classes III, IV, and V shows that many
  K-type stars in the sample, including a large number of RS CVn binaries,
  show an anomalously high Li abundance relative to typical inactive stars
  of the same spectral type. Only a few stars in the sample are likely to
  be premain sequence objects of stars which have recently arrived on the
  main sequence. Mechanisms that could lead to the enhanced Li absorption
  in chromospherically active stars are discussed; these encompass large
  cool spots on the stellar surface, the production of Li in stellar
  flares by spallation reactions, and the evolution from main-sequence
  progenitors without, or with very shallow, outer convective zones.

---------------------------------------------------------
Title: Proposed Upgrade of the McMath Solar/Stellar Telescope to a
    4 m Aperture
Authors: Giampapa, M. S.; Livingston, W. C.; Rabin, D. R.
1992LNP...397..279G    Altcode: 1992sils.conf..279G
  No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic Signatures of Active Regions on Main Sequence
    Stars
Authors: Giampapa, Mark S.
1992LNP...397...90G    Altcode: 1992sils.conf...90G
  The observed characteristics of Ha in M dwarf stars combined with a
  consideration of chromospheric line formation in cool dwarfs suggests
  that it is radial structure, rather than lateral inhomogeneities,
  which is the predominant factor in controlling chromospheric activity
  in low mass stars. This conclusion implies, in turn, that chromospheres
  determined by a single heating rate are relatively widespread on the
  stellar surface. The implications for magnetic field structures depend
  upon whether there is a unique association between chromospheric heating
  rate and specific kinds of magnetic field configurations. Synoptic
  observations of the marginal BY Draconis stars revealed irregular
  variability in the total strength and the positions of features in the
  their unique chromospheric Ha line. Further work must be done in order
  to ascertain the kind of chromospheric structures that yield the range
  of observed profiles. The special, and apparently rare, conditions
  that give rise to this subset of the low mass dwarfs remaim elusive.

---------------------------------------------------------
Title: Lithium Abundances in Northern RS CVn Binaries
Authors: Randich, S.; Giampapa, M. S.; Pallavicini, R.
1992ASPC...26..576R    Altcode: 1992csss....7..576R
  No abstract at ADS

---------------------------------------------------------
Title: Lithium in RS CVn Binaries and Related Chromospherically
    Active Stars
Authors: Pallavicini, R.; Randich, S.; Giampapa, M. S.
1992LNP...397..108P    Altcode: 1992sils.conf..108P
  No abstract at ADS

---------------------------------------------------------
Title: The Nature of the Dynamo at the End of the Main Sequence:
    A ROSAT Survey of the Late M Dwarfs
Authors: Fleming, T. A.; Giampapa, M. S.; Schmitt, J. H. M. M.;
   Bookbinder, J. A.
1992ASPC...26...93F    Altcode: 1992csss....7...93F
  No abstract at ADS

---------------------------------------------------------
Title: Next Generation Ultraviolet Astronomy with the Deep Ultraviolet
    Explorer Observatory
Authors: Ferguson, D. H.; Giampapa, M. S.
1992ASPC...26..629F    Altcode: 1992csss....7..629F
  No abstract at ADS

---------------------------------------------------------
Title: The Chromospheric Activity of Low-Mass Stars in the Hyades
Authors: Stauffer, John R.; Giampapa, Mark S.; Herbst, William;
   Vincent, James M.; Hartmann, Lee W.; Stern, Robert A.
1991ApJ...374..142S    Altcode:
  High-resolution spectra or narrow-band H-alpha photometry of 106 dwarf
  K and M stars in the Hyades cluster have been used to determine H-alpha
  equivalent widths. These data reveal a sequence of Hyades members with
  H-alpha in absorption for photospheric temperatures hotter than about
  3500 K. Within this sequence, the dispersion about the mean equivalent
  width-color relation is only slightly larger than the measurement
  errors. A second sequence of Hyades members, characterized by H-alpha
  emission and significant scatter at a given color, appears at effective
  temperatures cooler than about 4000 K. This bifurcation in H-alpha
  properties at 4000 K coincides with a bifurcation in the rotational
  characteristics of Hyades stars: the dispersion in the rotational
  velocities of the hotter Hyades members at a given effective temperature
  is small while the cooler stars exhibit significant scatter in their
  rotational velocities. On the basis of these data, it is suggested
  that low-mass stars spin down to rotational velocities dependent upon
  mass and age, but independent of premain-sequence angular momentum.

---------------------------------------------------------
Title: Magnetic Activity in Pre-Main Stars
Authors: Feigelson, Eric D.; Giampapa, Mark S.; Vrba, Frederick J.
1991suti.conf..658F    Altcode:
  The extensive new evidence for extremely high levels of magnetic
  activity on the surface of premain-sequence stars is reviewed and
  analyzed in the context of solar evolution. Most of these observations
  concern 'weak' T Tauri stars, in which the surface properties of the
  young stars are not dominated by circumstellar matter as in 'classical'
  T Tauri stars. Optical photometry shows that weak T Tauria stars are
  moderately rapid rotaters with cool starspots covering 5 to 40 percent
  of the surface. Optical and ultraviolet spectroscopy indicates that
  their chromospheres are enhanced about 50 times over contemporary solar
  levels. X-ray and radio intensities are of order 1000 to 100,000 times
  greater than peak solar levels, and they vary on time scales of days and
  (in a few cases) hours or minutes. The variability can only be explained
  in terms of some extremely powerful magnetic-flare model. The large
  numbers of weak T Tauri stars, probably larger than the population of
  classical T Tauri stars, strongly suggests that the sun was a weak
  T Tauri star for at least part of its premain-sequence evolutionary
  phase. These findings are summarized in a suggested portrait of the
  sun as a 1 Myr old weak T Tauri star.

---------------------------------------------------------
Title: The sun in time
Authors: Sonett, Charles P.; Giampapa, Mark S.; Matthews, Mildred S.
1991suti.conf.....S    Altcode:
  Various papers on solar science are presented. The optics considered
  include: variability of solar irradiance, sunspot number, solar
  diameter, and solar wind properties; theory of luminosity and radius
  variations; standard solar models; the sun and the IMF; variations of
  cosmic-ray flux with time; accelerated particles in solar flares; solar
  cosmic ray fluxes during the last 10 million yrs; solar neutrinos and
  solar history; time variations of Be-10 and solar activity; solar and
  terrestrial components of the atmospheric C-14 variation spectrum; solar
  flare heavy-ion tracks in extraterrestrial objects. Also addressed are:
  the faint young sun problem; atmospheric responses to solar irradiation;
  quaternary glaciations; solar-terrestrial relationships in recent sea
  sediments; magnetic history of the sun; pre- and main-sequence evolution
  of solar activity; magnetic activity in pre-main-sequence stars;
  classical T Tauri stars; relict magnetism of meteorites; luminosity
  variability of solar-type stars; evolution of angular momentum in
  solar-mass stars; time evolution of magnetic fields on solarlike stars.

---------------------------------------------------------
Title: The Sun in Time
Authors: Sonett, Charles P.; Giampapa, Mark S.; Matthews, Mildred
   Shapley
1991suti.book.....S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The solar-stellar connection
Authors: Giampapa, Mark S.
1990Natur.348..488G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Chromospheric H alpha and CA II Lines in Late-Type Stars
Authors: Robinson, Richard D.; Cram, Lawrence E.; Giampapa, Mark S.
1990ApJS...74..891R    Altcode:
  Observations of H-alpha and Ca II H and K in the chromospheres of 50
  main-sequence K and M stars are reported. The photospheric contribution
  to the integrated core flux in these lines is found to be more important
  than previously thought, and earlier estimates of the basal flux of cool
  dwarf stars are revised. The H-alpha data confirm the presence of both
  an upper and a lower limit to the H-alpha equivalent width attained
  at any given spectral type. The maximum H-alpha absorption strength
  decreases gradually toward cooler stars while the maximum 'saturated'
  quiescent emission strength increases. The Ca II emission strength
  is related to the strength of the emission or absorption feature at
  H-alpha, but there is not a one-to-one correlation. The main results may
  be explained in terms of photoionization and collisional control of the
  non-LTE H-alpha source function. Several aspects of the structure and
  heating of the outer atmospheres of dwarf K and M stars are discussed.

---------------------------------------------------------
Title: Lithium in chromospherically active stars.
Authors: Pallavicini, R.; Randich, S.; Giampapa, M.; Cutispoto, G.
1990Msngr..62...51P    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Rotational modulation and flares on RS Canum Venaticorum and
    BY Draconis-type stars. XV. Observations of Proxima Centauri and
    solar calibration data.
Authors: Haisch, B. M.; Butler, C. J.; Foing, B.; Rodono, M.; Giampapa,
   M. S.
1990A&A...232..387H    Altcode:
  Results are reported from simultaneous Exosat and IUE observations
  of flaring in Proxima Cen on March 2, 1985. The data are presented in
  extensive tables and sample spectra and discussed in detail. The peak
  emission of the soft-X-ray flare is found to be about 3 x 10 to the 27th
  erg/sec, with energy about 3 x 10 to the 30th erg and an associated
  increase in Mg II flux to 17,000-67,000 erg/sq cm sec, or about an
  order of magnitude lower than the solar value. The presence of flare-
  and microflare-related processes heating the corona is inferred.

---------------------------------------------------------
Title: Introduction - Sun in Time - Conference - Tucson - 1989MAR6-10
Authors: Sonett, Charles P.; Giampapa, Mark S.
1990SoPh..127..295S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Book Review: The restless sun / Smithsonian Institution
    Press, 1989
Authors: Giampapa, M. S.
1989S&T....78..602G    Altcode: 1989S&T....78..602W
  No abstract at ADS

---------------------------------------------------------
Title: A Search for Chromospheres at Faint Magnitudes
Authors: Fleming, Thomas A.; Giampapa, Mark S.
1989ApJ...346..299F    Altcode:
  The preliminary results of a program to detect chromospheric Ca
  II K line emission in the faintest dwarf stars yet observed at this
  wavelength using high spectral resolution are reported. The star LHS 429
  (VB 8; dM7e) exhibits K line emission in addition to H-alpha emission
  while LHS 2 (dM5-5.5) shows K line emission although no apparent
  H-alpha feature was seen in a spectrum obtained during the course
  of an earlier study by Giampapa and Liebert. A further seven stars
  observed did not exhibit any apparent feature at the position of the
  K line. The upper limits estimated for the K line surface flux in the
  case of the nondetections are still consistent with these stars having
  chromospheres characterized by a level of K line emission similar to
  that of LHS 2. The trend of the measured K line widths with absolute
  visual magnitude is qualitatively in accord with that expected from
  the Wilson-Bappu effect.

---------------------------------------------------------
Title: The CA II resonance lines in M dwarf stars without H-alpha
    emission.
Authors: Giampapa, Mark S.; Cram, Lawrence E.; Wild, Walter J.
1989ApJ...345..536G    Altcode:
  Spectra of the Ca II H and K lines in a sample of 31 M dwarf stars
  without H-alpha emission are used to calculate chromospheric K
  line radiative losses, F(k), and to study the joint response of Ca
  II K and H-alpha to chromospheric heating in dwarf M stars. It is
  suggested that the poor correlation found in the equivalent width
  - log F(K) diagram may be due either to radial segregation of the
  H-alpha and K line forming regions or to lateral inhomogeneities
  in the chromospheres. The results confirm the existence of dM stars
  with weak H-alpha absorption and K line emission only slightly weaker
  than that of the dMe stars, and show that dM stars with weak H-alpha
  but kinematics and metallicities representative of the young disk
  population belong to a class characterized by a comparatively high
  degree of chromospheric activity.

---------------------------------------------------------
Title: Analysis of the Chromospheric Spectrum of "Marginal" BY
    Draconis Stars
Authors: Giampapa, M. S.
1989BAAS...21.1116G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Variability of Chromospheric Lines in Late-Type Dwarf Stars
Authors: Cutispoto, Giuseppe; Giampapa, Mark S.
1988PASP..100.1452C    Altcode:
  The results of a high-resolution spectroscopic synoptic program of
  observations of key chromospheric diagnostics in a sample of dwarf
  stars are reported. Low-level variability in the strength of the
  chromospheric H-alpha absorption line is found. The nature of the
  variability implies that the operative chromospheric heating mechanism
  is partially characterized by a transient component. This fact, combined
  with the detectability of the low-level variability, suggests that
  magnetic field-related, nonradiative atmospheric heating is widespread
  in the dM stars. High-amplitude variability in the H-alpha emission
  strength of the active dMe star BY Dra was also observed. Synoptic
  observations of the He I 5876 A absorption line in three solar-type
  stars revealed low-level variability in the strength of this feature.

---------------------------------------------------------
Title: The High Resolution Spectroscopic Synoptic Program at the
    McMath Telescope
Authors: Jaksha, D.; Giampapa, M. S.
1988BAAS...20..998J    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Multiwavelength observations of magnetic fields and related
    activity on Xi Bootis A.
Authors: Saar, S. H.; Huovelin, J.; Giampapa, M. S.; Linsky, J. L.;
   Jordan, C.
1988ASSL..143...45S    Altcode: 1988acse.conf...45S
  The authors present preliminary results of coordinated observations
  of magnetic fields and related activity on the active dwarf, ξ Boo
  A. Combining the magnetic fluxes with the linear polarization data,
  a simple map of the stellar active regions has been constructed.

---------------------------------------------------------
Title: Evolutionary Changes in the UV and EUV Flux of the Sun
Authors: Giampapa, M.
1988srov.proc..241G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Formation of Chromospheric Lines in Cool Dwarf Stars
Authors: Cram, L. E.; Giampapa, M. S.
1987ApJ...323..316C    Altcode:
  A simple theory of the formation of H-alpha and Ca II K in dwarf M
  stars has been developed which relates the observed variations in the
  emission strengths of Ca II K and the equivalent widths of H-alpha to
  physical differences in the underlying chromospheric structure of the
  stars. The theory implies that Ca II K line emission fluxes increase
  monotonically with increasing chromospheric temperature or mass
  loading. However, H-alpha equivalent widths may increase or decrease
  with increasing chromospheric temperature or mass loading, depending
  on the actual values of the chromospheric parameters and the effective
  temperature. The theory is used to elucidate aspects of the available
  observational data on H-alpha and Ca II K lines in late-type dwarfs.

---------------------------------------------------------
Title: Simultaneous Observations of the Hα and Mg II Resonance Line
    Profiles in the T Tauri Star SU Aurigae
Authors: Giampapa, M. S.; Imhoff, C. L.
1987BAAS...19.1026G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Solar-Stellar Connection
Authors: Giampapa, Mark S.
1987S&T....74..142G    Altcode:
  The role of magnetic fields in the relation between solar and stellar
  theories is studied. The strength of a magnetic fields is related to the
  structure of a star's outer convection zone and stellar parameter such
  as rotation rate and surface gravity. The analyses of H and K emission
  lines of calcium for the sun and stars reveal the presence of plages and
  spots in both the sun and stars. The correlation between stellar winds,
  and coronal and chromospheric activity is investigated. It is determined
  that the magnetic field causes an interaction between a star's rotation
  and violent convective motions in its atmosphere. The magnetoacoustic
  hypothesis for heating the coronae is described. Research planned for
  the study of the solar-stellar relationship is discussed.

---------------------------------------------------------
Title: A Catalog of Mg II Emission Line Fluxes for T Tauri Stars
Authors: Imhoff, C. L.; Basri, G.; Giampapa, M. S.
1987BAAS...19..728I    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Status Report on the SYNOP Project to Monitor Stars with
    High-Resolution Spectroscopy
Authors: Linsky, J. L.; Giampapa, M. S.
1987BAAS...19..701L    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Spatial Distribution of Magnetic Fields on Xi Bootis A
Authors: Saar, S. H.; Huovelin, J.; Giampapa, M. S.
1987BAAS...19..703S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Atmospheres of Stars in the Limit of Thin and Thick Convection
Zones: The M Dwarf Stars (Invited review)
Authors: Giampapa, Mark S.
1987LNP...291..236G    Altcode: 1987csss....5..236G; 1987LNP87.291..236G
  This review summarizes our present understanding of the properties of
  M dwarf chromospheres and coronae determined from x-ray emission and
  ultraviolet and optical emission lines. These data permit estimates
  of the energy balance and heating rates for both dM and dMe stars and
  the presence of active regions. Two important questions are whether
  the dynamo is qualitatively different for the fully convective stars
  and whether the outer layers of dM stars are heated acoustically.

---------------------------------------------------------
Title: Magnetic Field Measurements on the Sun and Implications for
    Stellar Magnetic Field Observations
Authors: Sun, Wei-Hsin; Giampapa, Mark S.; Worden, Simon P.
1987ApJ...312..930S    Altcode:
  Results of solar magnetic field measurements in plages, sunspot umbrae,
  and sunspot penumbrae using high spectral resolution, unpolarized
  infrared H band spectral data are presented. A Fourier deconvolution
  analysis scheme similar to that utilized for stellar magnetic field
  measurements is adopted. As an example, a field strength of 3240 + or -
  450 G is determined in a sunspot umbra combined with a value of 2000 +
  or - 180 G in the associated penumbra. These values are compared with a
  direct measurement of the spot umbra and penumbra field strengths based
  on the observed separation of the Zeeman components of the magnetically
  sensitive lines. Possible origins for the discrepancy between the
  results inferred by these two different techniques are discussed. The
  Fourier analysis results confirm the widespread occurrence of kilogauss
  level fields in the solar photosphere. The implications of the solar
  results for stellar magnetic field measurements are considered.

---------------------------------------------------------
Title: 4 meter FTS observations of photospheric magnetic fields on
    M dwarfs.
Authors: Saar, Steven H.; Linsky, Jeffrey L.; Giampapa, Mark S.
1987LIACo..27..103S    Altcode: 1987oahp.proc..103S
  Much of the observed activity on M dwarfs (e.g., spots, flares,
  chromospheric and coronal emission) has been attributed to the
  interaction of magnetic fields with the stellar atmosphere. Since data
  on the magnetic field parameters of M dwarfs can potentially reveal much
  about the physical mechanisms behind these phenomena and, additionally,
  about stellar dynamos and the evolution of stellar angular momentum,
  the authors have begun a program to measure the mean magnetic field
  strength in stellar active regions, and the surface filling factor of
  these regions for a sample of M dwarfs. In this paper some preliminary
  results of this survey are discussed.

---------------------------------------------------------
Title: Non-Axisymmetric Winds in T Tauri Stars
Authors: Giampapa, Mark S.
1987iue..prop.2782G    Altcode:
  We propose to obtain high dispersion, large aperture LWP observations
  of the Mg II h and k lines of a T Tauri star during the course of
  its rotation period in order to determine the empirical relationship
  between surface magnetic field regions and winds and mass loss in T
  Tauri stars. More specifically, we propose to monitor the Mg II hand k
  line profiles during the rotation period of a T Tauri star to search for
  evidence of rotational modulation in the blue wings. Such modulation
  (in both position and the intensity of the wind absorption) would be
  expected if the wind regions are intimately linked to magnetic field
  configurations, similar to solar coronal holes, on or near the stellar
  surface. This phenomenon has recently been observed with the IUE by
  Praderie at al. (1986) in the wind of AB Aur and thus constitutes
  the first direct evidence of a non-axisymmetric wind in an A type
  pre-main sequence star. Clearly, it would be extremely interesting
  to determine if this phenomenon is present in the precursors of
  late-type, solar-like stars, namely, the T Tauri stars. The detection
  of a nonaxisymmetric wind component in a T Tauri star would strongly
  support the hypothesis that mass loss in T Tauri stars is associated
  with nonradiative heating. Magnetic field related mass loss mechanisms,
  such as the Alfven wave driven winds, would consequently become more
  applicable in the context of mass loss from T Tauri stars. Our previous
  work indicates that the Mg II 2800 lines are the best diagnostics
  of physical conditions in the wind acceleration region between the
  lower chromosphere and the more extended regions in the wind. In
  addition, we will supplement these IUE observations with simultaneous
  ground-based observations of the H-alpha profile. In this way we can
  discern the radial extent of magnetic-field-related variability in the
  wind component of the profile as modulated by rotation. This additional
  component of the proposed program may provide a valuable constraint on
  the lower bound for the Alfven radius in a pre-main sequence star. We
  propose to acquire high dispersion LWP observations of the Mg II h and
  k lines in the T Tauri star SU Aurigae. The upper limit to its rotation
  period is 3.8 days; hence, we request 4 shifts to completely cover a
  rotation period. The choice of SU Aur is dictated by the fact that
  this T Tauri star exhibits both strong X-ray emission and evidence
  for strong mass loss that Is variable. Thus, both open and closed
  magnetic field regions are likely present on the stellar surface if
  the solar analogy is applicable. The feasibility of this IUE program
  has been demonstrated by two previous high dispersion observations of
  SU Aur. In order to obtain adequate signal-to-noise, an exposure of
  7 hr is required. We must therefore request US1 shifts entirely. If
  approved, this program would represent the first time a T Tauri star
  has been monitored for line profile variations during a rotation period.

---------------------------------------------------------
Title: MOST: Multiple Object Spectroscopic Telescope.
Authors: Pilachowski, C.; Giampapa, M.; Barden, S.; Green, R.;
   Osmer, P.
1987inco.conf...53P    Altcode:
  MOST is a multiple object spectroscopic telescope based on the
  anticipated available of a 4 m, f/1.5 mirror from the NNTT mirror
  development program. The authors describe the MOST concept and give
  examples of how it can be applied to cosmological problems.

---------------------------------------------------------
Title: The McMath Solar-Stellar Synoptic Program
Authors: Smith, Myron A.; Giampapa, Mark S.
1987LNP...291..477S    Altcode: 1987LNP87.291..477S; 1987csss....5..477S
  No abstract at ADS

---------------------------------------------------------
Title: Synoptic Observations of the He I λ5876 Line in Active,
    Solar-Type Stars
Authors: Giampapa, M. S.
1986BAAS...18..982G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: IUE observations of the eruptive pre-main sequence object
    FU Orionis.
Authors: Ewald, R.; Imhoff, C. L.; Giampapa, M. S.
1986ESASP.263..205E    Altcode: 1986NIA86......205E; 1986niia.conf..203E
  IUE observations have been used to examine the nature of
  the eruptive pre-main sequence object FU Orionis. The Mg II
  emission line is quite strong, with a surface flux of about
  1.8×10<SUP>8</SUP>erg/cm<SUP>2</SUP>sec, and probably arises in a
  wind and extended envelope. The Mg II h and k line profiles appear
  to be P Cygni, indicating that a substantial wind persists 50 years
  after the original outburst in the star. The ultraviolet spectrum,
  aside from the Mg II emission, resembles F2 Ia standard star spectra.

---------------------------------------------------------
Title: High-Resolution H alpha Observations of M Dwarf Stars:
    Implications for Stellar Dynamo Models and Stellar Kinematic
    Properties at Faint Magnitudes
Authors: Giampapa, M. S.; Liebert, J.
1986ApJ...305..784G    Altcode:
  We present high-dispersion observations of the Hα spectral region for a
  sample of very late M dwarf stars, as obtained with the Multiple Mirror
  Telescope echelle spectrograph and Reticon detector. Radial velocities
  and total space motions are derived. The Hα emission line properties
  of our sample are thereby examined according to membership in stellar
  kinematic populations. We find that, contrary to previous assertions,
  M dwarf stars exist later than spectral type M5.5 which do not exhibit
  Hα line emission. In fact, there are comparable numbers showing and
  not showing Hα emission for M<SUB>v</SUB> &gt; + 15 in this sample of
  large proper motion stars. Thus, the onset of full convection along the
  main sequence does not necessarily imply an enhanced level of magnetic
  field related chromospheric activity. However, we do find for the small
  and biased sample considered in this investigation that dMe stars are
  the dominant class of objects for absolute magnitudes M<SUB>v</SUB>
  &gt; + 17. The dMe stars tend to exhibit the small total space motions
  and (U, V, W) velocity dispersions that are indicative of young disk
  kinematics, while nearly all the M dwarfs lacking Hα emission are
  members of either the old disk or halo kinematic populations. The
  faintest subdwarf included in this investigation has M<SUB>v</SUB>
  ≍ +14.8. The implications for stellar dynamo theory and for the
  nature of the stellar luminosity function at faint magnitudes are
  discussed. In particular, the results constitute corroborative evidence
  for a rotation-dependent distributed dynamo as a viable model for the
  generation of magnetic flux in the very low mass stars. Our results
  also suggest no significant difference between the kinematic properties
  of the stellar population that is brighter than the likely maximum in
  the luminosity function and that which is fainter.

---------------------------------------------------------
Title: The Surface Magnetic Fields of dM and dMe Stars
Authors: Saar, S. H.; Linsky, J. L.; Giampapa, M. S.
1986BAAS...18..670S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Nature of the Dynamo in the Very Late M Dwarf Stars
Authors: Giampapa, Mark S.; Liebert, James
1986LNP...254...62G    Altcode: 1986csss....4...62G
  The results demonstrate that there are non-dMe stars with spectral
  types later than M5.5. We also confirm the occurrence of dMe stars
  at very late spectral types that, on the basis of current models,
  correspond to fully convective interiors. Hence, the results support
  a rotation-dependent distributed dynamo (or some variation thereof)
  as a viable model for the generation of magnetic flux in the very low
  mass stars. Future work should include v sin i determinations in order
  to further extend the investigation of the properties of dynamos,
  the kinematics, and the occurrence of binaries in the very low mass
  stars. The acquisition of Ca II H and K line data for the old disk and
  halo population stars in order to verify if any chromospheric activity
  is at all present would prove valuable. Many of the known low luminosity
  M dwarfs should be targeted for observation with future X-ray satellite
  observatories. A monitoring program to determine whether cycles occur
  in the fully convective M dwarf stars would provide valuable input on
  the location of dynamo processes in the stellar interior, as suggested
  by Dr. P. Gilman during the course of this workshop.

---------------------------------------------------------
Title: Prospects for a new synoptic high resolution spectroscopic
    observing facility
Authors: Giampapa, Mark S.
1986pnsh.conf.....G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Summary of the Synoptic Spectroscopic Facility Workshop
Authors: Giampapa, M. S.
1986tswo.work..145G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: SHIRSOG Workshop / National Solar Observatory, Tucson,AZ., 1986
Authors: Giampapa, Mark S.
1986tswo.work.....G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: T Tauri stars: flare characteristics and flare models.
Authors: Giampapa, M. S.
1986RALR...85..232G    Altcode:
  The author notes the results of some recent work concerning surface
  magnetic activity on T Tauri stars. Then he discusses the flare
  properties of T Tauri stars.

---------------------------------------------------------
Title: The SHIRSOG Workshop. Proceedings of a workshop on prospects
    for a new synoptic high resolution spectroscopic observing facility,
    held at the National Solar Observatory, National Optical Astronomy
    Observatories, Tucson, Arizona, USA, 3 September 1986.
Authors: Giampapa, M. S.; Jefferies, J. T.; Linsky, J. L.
1986swpw.book.....G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Synoptic Studies of T-Tauri Stars
Authors: Giampapa, M. S.
1986tswo.work...53G    Altcode:
  The synoptic study of pre-main sequence stars at non-redundant
  wavelengths throughout the electromagnetic spectrum can elucidate
  critical problems in stellar evolution. Among these problems are:
  (1) The process of star formation in molecular clouds. (2) The
  redistribution of angular momentum as cloud collapse occurs. (3)
  The evolution of stellar magnetic activity up to the ZAMS. (4) The
  origin of chromospheres and coronae, including the operative heating
  mechanisms in the atmosphere and the associated mass flows. These
  processes may ultimately influence the structure of the star forming
  region and thereby play a role in regulating star formation rates.

---------------------------------------------------------
Title: Chromospheric and Coronal Emission in DM Stars
Authors: Giampapa, Mark S.
1986iue..prop.2455G    Altcode:
  We propose to obtain low dispersion, large aperture LWP spectra of the
  Mg II h+k chromospheric resonance lines for a volume limited sample
  of mainly single dM (i.e., nondMe) stars for which X-ray data are
  available. The combination of the IUE data-set we propose herein to
  obtain and the previously acquired X-ray data-set (Bookbinder 1985)
  will yield further insights on the nature of chromospheric and coronal
  heating in the ordinary, inactive (quiescent) dM stars. In particular,
  if the X-ray heating hypothesis for the source of chromospheric heating
  in the dMe stars, as advanced by Cram (1982), is also applicable to the
  dM stars then we would expect to find a linear correlation between the
  luminosity in the Mg II lines and the X-ray luminosity. In general, if a
  common source of in situ heating in the chromospheres and coronae of the
  dM stars is present then we would expect to find a linear relationship
  between the observed Mg II emission and the X-ray emission. Conversely,
  if the sources of chromospheric and coronal heating are different
  between these atmospheric regions in the dM stars then we expect to
  find a departure from a simple linear relationship. The results to be
  obtained in this program will yield critical observational constraints
  on the possible mechanisms for atmospheric heating in the dM stars.

---------------------------------------------------------
Title: The filling factor of active regions on the surfaces of the
    dM stars.
Authors: Giampapa, M. S.
1985ApJ...299..781G    Altcode:
  According to the appearance of the H-alpha line in their spectra, the M
  dwarf stars are subdivided into two classes, including the dMe stars and
  the dM stars. Arguments, based on the unique properties of H-alpha line
  formation in the M dwarf stars, are presented to demonstrate that the
  surfaces of the dM stars must be characterized by a significant areal
  coverage (or 'filling factor') of presumably magnetic field-related
  active regions. In addition, an estimate regarding the lower limit to
  the filling factor of chromospheric regions on dM stars is obtained, and
  an empirical relation is provided for the upper limit to the intrinsic
  Ca II (and Mg II) emission in these stellar surface regions. The
  discussion utilizes general model results obtained by Cram and Mullan
  (1979) and Giampapa et al. (1982).

---------------------------------------------------------
Title: Stellar magnetic field measurements utilizing infrared
    spectral lines.
Authors: Gondoin, Ph.; Giampapa, M. S.; Bookbinder, J. A.
1985ApJ...297..710G    Altcode:
  High-resolution spectra obtained with the KPNO 4 m telescope and FTS
  in the infrared H and K bands are examined in order to select spectral
  lines suitable for measurements of stellar magnetic field strengths and
  filling factors. Only four lines are found suitable for the magnetic
  field measurement technique adopted in this study. The authors analyze
  the co-added spectra of the active stars ξ Boo A (G8 V), 61 UMa
  (G8 V) and λ And (G8 IV-III) as obtained during four consecutive
  nights. The analysis technique involves the Fourier deconvolution
  of magnetically sensitive and insensitive line profiles in a single
  spectrum. No evidence for the presence of magnetic fields is detected
  in the co-added spectra of either ξ Boo A or 61 UMa. The data for λ
  And suggest magnetic fields of ≡600 G extending over at least 20%
  of the visible hemisphere. However, these values are near the detection
  limit for the spectrum of λ And.

---------------------------------------------------------
Title: Synoptic Observations of the Li I λ6707 Line in a Sample of
    Solar-Type Stars
Authors: Giampapa, M. S.
1985BAAS...17..902G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Simultaneous observations of CA II K and MG II K in T TAuri
    stars.
Authors: Calvet, N.; Basri, G.; Imhoff, C. L.; Giampapa, M. S.
1985ApJ...293..575C    Altcode:
  The first simultaneous, calibrated observations of the Ca II K and
  Mg II k resonance lines in T Tauri stars are presented. It is found
  that for T Tauri stars with mass greater than 1.5 solar mass, which
  have radiative cores and tend to be fast rotators, the k line seems to
  arise in an extended region (probably also responsible for the H-alpha
  emission), whereas the K line apparently originates closer to the highly
  inhomogeneous stellar surface. The lower mass stars, which are fully
  convective and tend to be slow rotators, are more easily described by
  a largely chromospheric model, consistent with main-sequence activity
  structures but at greater values of the nonradiative flux. The strongest
  emission-line stars in the low-mass group, however, are also likely
  to have extended k line regions.

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

---------------------------------------------------------
Title: The ambient radiation field of young solar systems: ultraviolet
    and X-ray emission from T Tauri stars.
Authors: Giampapa, M. S.; Imhoff, C. L.
1985prpl.conf..386G    Altcode:
  The authors review the principal results that have emerged from
  ultraviolet and X-ray observations of T Tauri stars. They emphasize
  that, as seen in the ultraviolet, T Tauri stars are characterized by
  strongly enhanced emission. The X-ray emission and its variability,
  when detected, is also enhanced and indicate of the occurrence of
  violent flare activity near the stellar surface. The authors discuss
  possible effects of these enhanced emissions on conditions in early
  solar systems and the chemical evolution of early planetary atmospheres.

---------------------------------------------------------
Title: Profiles of the MG II H and K Lines in Selected Red Dwarfs
Authors: Giampapa, Mark S.
1985iue..prop.2149G    Altcode:
  We propose to obtain high dispersion, large aperture, flux-calibrated
  LWP observations of the Mg II h and k resonance lines for a selected
  sample of 8 red dwarf stars in the spectral range dK7 - dM4.5. The
  sample includes 6 active chromosphere emission line stars and 1
  quiet chromosphere comparison dwarf. Furthermore, we will apply to
  arrange for simultaneous, high spectral resolution, flux-calibrated
  observations of the Ca II H and K lines and the H-alpha line using
  the KPNO 4m echelle spectrograph and CCD. The resulting data-set
  will be used to (1) develop self-consistent, semi-empirical model
  chromospheres with the eventual goal of gaining insight on the Possible
  atmospheric heating mechanisms operative in the chromospheres of
  these stars and the relative geometries of the line emitting regions,
  (2) testing the applicability of specific chromospheric scaling laws
  (Ayres 1979) to the Mg II lines in these stars, and (3) determine if
  the Wilson-Bappu effect persists through these late spectral types as
  seen in the Mg II lines as well as the Ca II and H-alpha lines. We will
  utilize a fully general, non-LTE transfer code at Berkeley to develop
  semi-empirical model chromospheres according to the techniques employed
  by Giampapa et al. (1982). The Mg II resonance lines in M dwarfs are
  particularly interesting since they are formed at a level between the
  lower chromospheric Ca II h and k lines and the upper chromospheric
  Balmer lines. Thus the Mg II lines represent a crucial "bridge" between
  these diagnostics. Moreover, the Mg II lines are significantly more
  optically thick than the Ca II lines by virtue of the greater (~ 10)
  abundance of magnesium relative to calcium. Thus they are potentially
  a more sensitive test of chromospheric scaling laws (Ayres 1979) for
  optically thick lines. Finally, an active star and a quiet chromosphere
  star of the same spectral types (dK7) are included in the observing
  program as a further test of the applicability of the Wilson-Bappu law
  to red dwarfs. According to this law, the widths should be identical
  within errors. Significant differences would be investigated within
  the context of differences in chromospheric structure which would,
  in turn, lead to new insights on chromospheric line formation and
  the Wilson-Bappu effect. The feasibility of this IUE program has been
  demonstrated by high dispersion, LWR observations of AU Mic (dM1.6e)
  of 4 hr duration during a US2 shift (Ayres et al. 1983). We use this
  result and low resolution Mg II flux measurements tabulated by Linsky et
  al. (1982) to obtain reliable LWP-high dispersion exposure estimates for
  the targets in our sample. We will precede each LWP - high with a LWP
  - low for accurate flux calibration purposes. In addition, we wish to
  bracket all exposures with FES visual magnitude estimates to check for
  flare activity. The LWP - high exposures for the more flare active stars
  in our program will be obtained in segments bracketed by FES magnitudes.

---------------------------------------------------------
Title: Stellar surface inhomogeneities and the interpretation of
    stellar spectra.
Authors: Giampapa, M. S.
1985ASIC..152..305G    Altcode: 1985pssl.proc..305G
  The author discusses manifestations of stellar surface thermal
  inhomogeneities in stellar spectra. He illustrates the effects
  of multi-components in stellar atmospheres on the interpretation
  of line diagnostics and single-component models as well as on the
  treatment of line transfer problems. The examples offered involve
  metal abundance determinations, chromospheric line diagnostics, the
  realistic representation of pre-main sequence atmospheres and stellar
  magnetic fields.

---------------------------------------------------------
Title: Coordinated Magnetic and Chromospheric Observations of Stars
Authors: Giampapa, Mark S.
1985iue..prop.2147G    Altcode:
  We propose to obtain time-resolved, coordinated observations of
  magnetic flux and the associated chromospheric and transition region
  line emissions for selected active chromosphere stars. The unique
  data to be obtained in this program will provide a crucial input to
  theories that describe the heating of stellar atmospheres. In essence,
  the results to be acquired through the observations will establish a
  preliminary empirical relationship between stellar photospheric magnetic
  field strengths and magnetic flux, and stellar outer atmospheric
  line emission. We are presently utilizing demonstrated methods to
  directly detect magnetic fields on stellar surfaces. Magnetic results
  indicate the existence of strong (a few kilogauss) fields that may
  cover up to 80% of the stellar surface. Moreover, these fields are
  observed to rapidly (2-3 days) vary in surface coverage, suggesting
  a single large magnetic spot complex on only one hemisphere of the
  star. We therefore propose a coordinated IUE/ground-based synoptic
  program to obtain chromospherictransition region data (with IUE),
  and photospheric magnetic field and flux measurements (ground-based
  observations) for several stars that exhibit rapidly varying surface
  field coverages over their rotational periods. Our IUE observing
  pattern will primarily consist of low dispersion, SWP observations
  and high-dispersion, LWR exposures. These data will be obtained
  simultaneously (or near simultaneously) with ground-based optical and
  IR observations. The ground-based data will be used to infer magnetic
  field strengths and flux in the photosphere. We also require that the
  IUE shifts be scheduled every third day to insure that we examine the
  entire stellar surface over 10-15 day rotational periods. We require
  two separate observing periods in order to have access to all objects
  in the target list from ground-based observing sites.

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

---------------------------------------------------------
Title: The appearance of magnetic flux on the surfaces of the early
    main-sequence F stars
Authors: Giampapa, M. S.; Rosner, R.
1984ApJ...286L..19G    Altcode:
  Available chromospheric, transition region, and coronal observations
  of the early main-sequence F stars are examined in order to find that
  while these objects exhibit enhanced levels of magnetic field-related
  radiative emissions, significant inhomogeneities in surface activity
  are not present. This phenomenon is discussed within the context of the
  calculations published by Schmitt and Rosner (1983) for the production
  of flux ropes of various spatial scales at a given rotation rate at
  the bottom of a stellar convection zone. It is found that the spatial
  scales and area contrast of emergent magnetic flux in these stars that,
  as a class, are characterized by rapid rotation and thin convection
  zones are substantially reduced relative to that of the sun.

---------------------------------------------------------
Title: The Filling Factor of Active Regions on non-dMe Stars
Authors: Giampapa, M. S.
1984BAAS...16..940G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Transition from Chromosphere to Wind for MgII in T Tauri
    Stars
Authors: Basri, G.; Calvet, N.; Imhoff, C. L.; Giampapa, M. S.
1984BAAS...16..938B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet Continuum and Mg II Emission Rotational Modulation
    in Three Pre-Main Sequence Stars
Authors: Imhoff, C. L.; Giampapa, M. S.
1984BAAS...16..997I    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Simultaneous IUE, Voyager, and Optical Observation of Epsilon
    Persei
Authors: Giampapa, Mark
1984iue..prop.1947G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: New spectrophotometry of the extremely cool proper motion
    star LHS 2924.
Authors: Liebert, J.; Boroson, T. A.; Giampapa, M. S.
1984ApJ...282..758L    Altcode:
  Improved spectrophotometric scans are presented for this very faint,
  red, large-proper motion star which has a peculiar spectrum. The
  Palomar Observatory 5 meter CCD spectrum shows the clear presence
  of VO λ7400 and λ7900. However, the TiO and hydride bands and
  the Na I and K I lines appear relatively weaker over the spectrum
  of LHS 2924 than they do in the benchmark low-luminosity star VB
  10. A high-resolution observation with the MMT echelle spectrograph
  shows very weak Hα emission, at best. These and other recent results
  eliminate all previously considered explanations of the nature of LHS
  2924 other than a very cool, main-sequence star or sub-stellar-mass
  "brown dwarf." The weakness of Hα emission tends to indicate that
  the star is an old, main-sequence object.

---------------------------------------------------------
Title: The Transition Regions of X-Ray Emitting Main-Sequence A Stars
Authors: Giampapa, Mark S.
1984iue..prop.1812G    Altcode:
  We propose to obtain low dispersion, large aperture SWP and high
  dispersion, large aperture LWR observations of two (2) X-ray emitting,
  single main-sequence A stars:: HR 7160 (A8V, log Lx = 29) and HD 117721
  (A3V, log Lx = 30.4). These stars were strongly detected by HEAO-B
  (Golub et al. 1983) and, unlike many of the other A stars detected by
  Einstein, these objects appear to be single stars. lie thus propose to
  verify the presence of hot plasma in these stars by searching for the
  occurrence of transition region and chromospheric line emission. The
  detection of transition region line emission (i.e. C IV, N V, Si IV,
  etc.) in main sequence A stars would have important implications for
  (1) our understanding of the precise location on the main sequence
  of the onset of convection, and (2) the role of convection zone depth
  and surface turbulence in the generation of stellar chromospheric and
  coronal activity.

---------------------------------------------------------
Title: Photometric variations of solar-type stars: results of the
    Cloudcroftsurvey.
Authors: Giampapa, M. S.
1984NASCP2310..173G    Altcode: 1984siva.work..173G
  The author summarizes the results of a synoptic program conducted
  at the Cloudcroft Observatory to search for the occurrence of
  photometric variability in solar-type stars as seen in continuum
  band photometry. The survey disclosed the existence of photometric
  variability in solar-type stars that is, in turn, related to the
  presence of spots on the stellar surface. Moreover, the observed
  variability detected in solar-type stars is at enhanced levels (≡1%)
  compared to that observed for the Sun.

---------------------------------------------------------
Title: Lithium abundances and chromospheric activity. I. Empirical
    results.
Authors: Giampapa, M. S.
1984ApJ...277..235G    Altcode:
  An empirical analysis is presented of the effects of chromospheric
  activity on lithium abundance determinations, as deduced from high
  signal-to-noise, high spectral resolution solar observations of
  the Li I resonance doublet at 6707.8 A. In particular, solar active
  (plage) regions and quiet comparison regions were observed to find a
  maximum relative change in the Li I 6707 equivalent width of -0.53
  among the limited number of solar plage observations available for
  this investigation. The relative weakening of the lithium resonance
  doublet is attributed to the increased ionization of neutral lithium
  due to the enhanced nonradiative heating that characterizes solar
  plages. The strong enhancement of the 6707 line in sunspot umbrae is
  confirmed and it is emphasized that the presence of stellar surface
  thermal inhomogeneities analogous to solar plages and sunspots can
  substantially alter the equivalent width of this feature in stellar
  spectra. Thus the effects of stellar chromospheric activity will
  introduce ambiguities into lithium abundance determinations that, in
  turn, can contribute significantly to the scatter in investigations
  that utilize this diagnostic.

---------------------------------------------------------
Title: Results from Ultraviolet Observations of T Tauri Stars
Authors: Giampapa, Mark S.
1984LNP...193...14G    Altcode: 1984csss....3...14G
  No abstract at ADS

---------------------------------------------------------
Title: The response of chromospheric emission lines to flares on YZ
    Canis Minoris.
Authors: Worden, S. P.; Schneeberger, T. J.; Giampapa, M. S.; Deluca,
   E. E.; Cram, L. E.
1984ApJ...276..270W    Altcode:
  Six flares of the dMe star YZ CMi have been observed with simultaneous
  photometry and high-dispersion, time-resolved spectroscopy.The spectra
  have temporal resolutions of 3 minutes with spectral resolutions
  of 0.24 Å. The largest observed flare had a U band amplitude of
  1.5 mag. Hα and Hβ line profiles did not broaden during any of the
  observed flares, although the line center intensity increased by over a
  factor of 2 during some flares. After the initial increase in intensity,
  the emission line strength decreases but remains at enhanced levels
  for hours following U band flares. The Hα flare luminosity and total
  energy are compared to corresponding properties of solar flares.

---------------------------------------------------------
Title: Direct and Indirect Methods of Measurement of Stellar
    Magnetic Fields
Authors: Giampapa, M. S.
1984srps.conf..309G    Altcode:
  Standard polarization methods for measuring stellar magnetic fields are
  inappropriate for solar-type field topologies. The author is therefore
  utilizing a "white-light" method that involves the interpretation
  of spectral line shapes as seen in high spectral resolution
  data. Through the application of Fourier deconvolution techniques,
  the field strength and area coverage on a stellar surface can be
  ascertained. The applicability and results of this method for both
  solar and stellar magnetic field measurements are discussed. Besides
  the aforementioned direct method, there potentially exist complementary
  indirect methods. They are less satisfactory than direct methods. They
  require a knowledge of the underlying physics that relates on observable
  radiative emission to the local magnetic field strength or flux.

---------------------------------------------------------
Title: Some Relevant Topics in Solar-Stellar Physics
Authors: Giampapa, M. S.
1984ssdp.conf..457G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Combined ultraviolet studies of astronomical sources
Authors: Dupree, A. K.; Giampapa, M. S.; Huchra, J. P.; Noyes,
   R. W.; Hartmann, L. W.; Raymond, J. C.; Blair, W. P.; Bothun, G. D.;
   Patterson, J. O.; Baliunas, S. L.
1983sao..reptR....D    Altcode:
  Ultraviolet spectra of non-radiataive shock waves grain destruction and
  elemental abundances in interstellar shocks, carbon abundance in M33
  and M31 from supernova remnants, determination of the mass function
  in the large Magellanic cloud, UV spectra of white dwarf pulsars,
  stellar flares, availability of the double quasar Q 0957 + 56' AB,
  spectra of late-F dwarfs and their relation to rotation, dynamics of
  hot gas surrounding hybrid stars, high resolution study of epsilon
  coronae Austriual, active regions on solar-type dwarfs as a function of
  rotation rate and age, coordinated chromospheric synoptic observations
  of selected late-type stars, the two-component atmosphere of Lambda
  Andromedae, and activity in Hyades giants are discussed.

---------------------------------------------------------
Title: Magnetic Field Measurements on the Sun and Synthesis of
    Stellar Spectrum from Solar Data
Authors: Sun, W.; Giampapa, M. S.; Worden, S. P.
1983BAAS...15..952S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The UV Variability of RW Aur
Authors: Imhoff, C. L.; Giampapa, M. S.
1983BAAS...15..928I    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Young Sun and The Atmosphere and Photochemistry of the
    Early Earth
Authors: Giampapa, M. S.; Canuto, V. M.; et al.
1983Natur.305..281G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Concerning Spot Formation in the Early Main Sequence F Stars
Authors: Giampapa, M. S.
1983BAAS...15..947G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The young Sun and the atmosphere and photochemistry of the
    early Earth
Authors: Canuto, V. M.; Levine, J. S.; Augustsson, T. R.; Imhoff,
   C. L.; Giampapa, M. S.
1983Natur.305..281C    Altcode:
  The origin and evolution of the Earth's early atmosphere depend
  crucially on the dissipation time t<SUB>N</SUB> of the primitive solar
  nebula, SN. Using different theories of turbulence, we estimate that
  for a 0.1 M<SUB>solar</SUB> SN, t<SUB>N</SUB> is 2.5-8.3Myr. Because
  accretion times are usually much longer, we conclude that most planetary
  accretion must have occurred in a gas-free environment. Using new IUE
  data, a wavelength-dependent UV flux is constructed for the young Sun
  which is then used to study the photochemistry and concentrations
  of O, O<SUB>2</SUB>, O<SUB>3</SUB>, OH, H, HCO and formaldehyde
  H<SUB>2</SUB>CO in the Earth's early prebiological atmosphere.

---------------------------------------------------------
Title: High Resolution Ultraviolet and Optical Observations of
    T-Tauri Stars
Authors: Giampapa, M. S.
1983RMxAA...7..195G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet Observations of the T-Tauri Stars - Inferences
    Regarding Their Chromospheres Transition Regions and Coronae
Authors: Imhoff, C. L.; Giampapa, M. S.
1983RMxAA...7..191I    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ultraviolet Observations of the T Tauri Stars: Inferences
    Regarding their Chromospheres, Transition Regions, and Coronae
Authors: Giampapa, M. S.
1983RMxAA...7..191G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: New Spectrophotometry of the Extremely Red Proper-Motion
    Star LHS2924
Authors: Liebert, J. W.; Boroson, T. A.; Giampapa, M. S.
1983nssl.conf..361L    Altcode: 1983IAUCo..76..361L; 1983LDP.....4..361L
  LHS 2924 (LP 271-25) is the uniquely-red, faint proper motion star
  recently reported to have a peculiar spectrum and colors by Probst
  and Liebert (1983). This paper reports briefly the results of two
  follow-up observations: an excellent red spectrum covering 5000 -
  9000 Å, and a high dispersion spectrum of the important Hα region.

---------------------------------------------------------
Title: The photometric variability of solar-type stars. II. Stars
    selected from Wilson's chromospheric activity survey.
Authors: Radick, R. R.; Wilkerson, M. S.; Worden, S. P.; Africano,
   J. L.; Klimke, A.; Ruden, S.; Rogers, W.; Armandroff, T. E.; Giampapa,
   M. S.
1983PASP...95..300R    Altcode:
  The authors have observed eleven solar-type main-sequence stars to
  search for continuum variability. Stars were selected from Wilson's
  chromospheric activity survey, and were observed for periods of three
  to six months with intermediate-band Stroemgren uvby photometry. The
  authors find evidence that two of these eleven stars are variable
  and that one other may be. Comparison with contemporaneous Ca II H +
  K emission flux measurements shows that the amplitude of photometric
  variability correlates strongly with both the mean emission flux
  and the amplitude of its variation. Variations in continuum light and
  emission flux tend to correlate in time, as well, with continuum minima
  coinciding with emission maxima and vice-versa. The authors infer that
  the surface activity of these stars tends to be confined to localized
  activity centers that include both emission plages and dark spots,
  similar to the active regions observed on the sun.

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

---------------------------------------------------------
Title: Methods and results for detecting magnetic fields on late-type
    stars.
Authors: Giampapa, M. S.; Worden, S. P.
1983IAUS..102...29G    Altcode:
  A program to detect and measure magnetic flux on the surfaces of
  late-type stars is discussed. A novel technique is adopted to deconvolve
  magnetically insensitive lines from similar, magnetically sensitive
  lines to infer the degree of Zeeman splitting in the latter lines. These
  measurements yield values for the magnetic field strength and filling
  factor (flux). To illustrate the approach multiple observations are
  presented of the RS CVn star Lambda And. At the epoch of observation
  26 April 1981 a field strength of 1290 + or - 50 gauss covering 48 +
  or - 2 percent of this stars's surface is found. Observations at other
  epochs clearly demonstrate magnetic flux variability on Lambda And.

---------------------------------------------------------
Title: Fractional stellar convection-zone depth and the generation
    of magnetic flux - an empirical approach
Authors: Giampapa, M. S.
1983IAUS..102..187G    Altcode:
  Preliminary results of an observational investigation of very late
  M dwarf stars utilizing the Multiple Mirror Telescope facility are
  presented. It is found that dwarf stars later than spectral type M5 do
  not necessarily exhibit H-alpha line emission, contrary to the assertion
  by Joy and Abt (1974). The preliminary results tentatively suggest,
  but do not prove, that the generation of significant magnetic fields
  and magnetic flux is severely inhibited in fully convective stars.

---------------------------------------------------------
Title: Observations of Flare Activity on Selected DME Flare Stars
Authors: Giampapa, Mark S.
1983iue..prop.1442G    Altcode:
  Optical and ultraviolet spectroscopy can enable the assessment of
  the physical conditions characterizing a stellar flare atmosphere and
  thereby potentially elucidate the possible radiative and hydrodynamic
  transport mechanisms operative during stellar flares. Observations
  of flares on M dwarf stars offers the opportunity to obtain detailed
  information on a solar-like phenomenon as it presumably occurs on many
  stars, but can presently only be observed on the cool dMe stars due
  to the highly favorable contrast between the UV and near UV bright
  flare emission and the faint quiescent background. We therefore
  propose to acquire timeresolved, low dispersion, large aperture SWP
  and LWR observations simultaneously with moderate resolution (3-4A)
  spectrophotometric optical observations of stellar flare events. We
  also will attempt to coordinate simultaneous VLA (radio corona)
  observations. We intend to monitor two highly flare active systems;
  the binary UV Ceti (GL65AB) system and the single flare star YZ CMi
  (GL 285). We wish to ascertain the dominant radiative transport
  mechanism that gives rise to the UV and optical continuum emission
  during flares as well as assess the relative energy balance in these
  wavelength regions. Furthermore, we will utilize density diagnostics and
  emission mesure analysis techniques developed for solar observations. In
  addition, we will infer flare X-ray luminosities from the enhancement
  of the He II 1640 recombination line. The UV data and inferred X-ray
  data will ultimately be used to determine the applicability of flare
  loop models. All data obtained in this program will be used as input
  for the construction of semiempirical flare atmospheres.

---------------------------------------------------------
Title: Results from optical and UV stellar flare spectroscopy
Authors: Giampapa, M. S.
1983ASSL..102..223G    Altcode: 1983ards.proc..223G; 1983IAUCo..71..223G
  Optical and ultraviolet spectroscopy can enable the assessment of
  the physical conditions characterizing a stellar flare atmosphere and
  thereby potentially elucidate the possible radiative and hydrodynamic
  transport mechanisms operative during stellar flares. In this review,
  illustrative examples are presented of the spectroscopic diagnostic
  techniques that can be applied to the analysis of stellar flare
  spectroscopic data and the resulting inferences concerning stellar
  flare properties for M dwarf flare events.

---------------------------------------------------------
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: Fractional Stellar Convection Zone Depth and the Generation
    of Magnetic Flux
Authors: Giampapa, M. S.
1982BAAS...14..865G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Stellar model chromospheres. XIII. M dwarf stars.
Authors: Giampapa, M. S.; Worden, S. P.; Linsky, J. L.
1982ApJ...258..740G    Altcode:
  Single-component, homogeneous model chromospheres that are consistent
  with high-resolution profiles of the Ca II K line calibrated in surface
  flux units for three dMe and 2 dM stars observed at quiescent times
  are constructed. The models reveal several systematic trends. Large
  values of the ratio of T(min) to T(eff) are derived, indicating a large
  amount of nonradiative heating present in the upper photospheres of M
  dwarf stars. It is also found that the lower chromospheric temperature
  gradient is similar for all the M dwarf stars. Since for the models here
  the chromospheric K line emission strength is most sensitive to the
  total amount of chromospheric material present within the approximate
  temperature range T(min)-6000 K, increasing the emission strength is not
  simply due to increasing chromospheric temperature gradients. It is also
  found that both the electron density and electron temperature at one
  thermalization length in the K line below the top of the chromospheres
  are greater in the dMe stars than in the dM stars. The M dwarf models
  here have microturbulent velocities between 1 and 2 km/sec, which are
  much smaller than for solar chromosphere models.

---------------------------------------------------------
Title: Observations of rapid line profile variability in the spectra
    of T Tau stars.
Authors: Mundt, R.; Giampapa, M. S.
1982ApJ...256..156M    Altcode:
  Observation of six T Tauri stars, having a spectral resolution
  of 240,000 and temporal resolutions in the 300-900 sec range, are
  presented. In addition to presenting evidence for the existence of rapid
  line profile variability in the spectrum of RW Aurigae, this object's
  line spectrum properties in the vicinity of the H-alpha, H-gamma, and
  Na D lines are discussed in view of three high-quality spectra, with
  the result that photospheric absorption features are identified and a
  rotational velocity of about 25 km/sec is tentatively estimated. The
  data set acquired for RW Aur also reveals the existence of mass motions
  with antiparallel velocity components in the line-emitting region of
  the object. A spectral type for this previously unclassified T Tauri
  star of K1 + or - 2 subclasses is determined.

---------------------------------------------------------
Title: Combined ultraviolet studies of astronomical sources
Authors: Dupree, A. K.; Giampapa, M. S.; Huchra, J. P.; Noyes, R. W.;
   Hartmann, L. W.; Raymond, J. C.
1982sao..reptQ....D    Altcode:
  Ultraviolet studies of astronomical sources are discussed. Some studies
  utilized IVE data. Non-radiative shock at the edge of the Cygnses Loop,
  stellar flares, local interestellar medium, hot galaxies, stellar mass
  ejection, contact binaries, double quasars, and stellar chromosphere
  and coronae are discussed.

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

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

---------------------------------------------------------
Title: Cool stars, stellar systems and the sun : 2 : 1981
Authors: Giampapa, M. S.; Golup, L.
1982SAOSR.392B....G    Altcode: 1982csss....2B....G
  No abstract at ADS

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

---------------------------------------------------------
Title: Far-ultraviolet and X-ray evidence concerning the chromospheres
    and coronae of the T Tauri stars.
Authors: Imhoff, C. L.; Giampapa, M. S.
1982SAOSR.392B.175I    Altcode: 1982csss....2..175I
  No abstract at ADS

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

---------------------------------------------------------
Title: The relevance of the IUE results on young stars for earth's
    paleoatmosphere.
Authors: Canuto, V. M.; Levine, J. S.; Augustsson, T. R.; Imhoff,
   C. L.; Giampapa, M. S.
1982NASCP2238..293C    Altcode: 1982auva.nasa..293C; 1982NASCP2338..293C
  Using the latest IUE results for seven T Tauri stars, which are believed
  to represent the young Sun and a detailed photochemical chemical model
  of the paleoatmosphere, the vertical distribution of Oxygen and Ozone
  in the early atmosphere was calculated. The calculations indicate that
  the surface Oxygen mixing ratio is as much as six orders of magnitude
  larger than previously estimated, but appears low enough for the
  formation of amino acids via the Urey-Miller type of experiments. It
  is believed that the quantification of the oxygen level in the Earth's
  paleoatmosphere presented can reconcile the demands of both biological
  and geological considerations.

---------------------------------------------------------
Title: Magnetic &amp; Chromospheric Synoptic Observations of
    Late-Type Stars
Authors: Giampapa, Mark S.
1982iue..prop.1099G    Altcode:
  We propose to obtain time-resolved, coordinated observations of
  magnetic flux and the associated chromospheric and transition region
  line emission for selected active chromosphere stars. The unique data
  to be obtained in this program will provide a crucial input to theories
  that describe the heating of stellar chromospheres and coronae. In
  essence, the results to be acquired through the observations proposed
  herein will (for the first time) establish a preliminary empirical
  relationship between stellar magnetic field strengths and magnetic flux,
  and stellar outer atmospheric line emission. We are presently utilizing
  a now and successfully demonstrated method to directly detect magnetic
  fields on stellar surfaces. These results indicate the existence of
  strong (~ a few kilogauss) magnetic fields that may cover up to 80%
  of the stellar surface. Moreover, these fields are observed to rapidly
  (2-3 days) vary in surface coverage. We therefore propose a coordinated
  IUE ground-based synoptic program to obtain chromospheric-transition
  region data (with IUE) and magnetic field and flux measurements
  (ground-based observations) for several stars that exhibit rapidly
  varying surface field coverages over their rotational periods. Our
  IUE observing pattern will primarily consist of low dispersion, SWP
  observations and high-dispersion, LWR exposures. These data will be
  obtained simultaneously (or near simultaneously) with groundbased
  optical and infrared observations. The groundbased data will

---------------------------------------------------------
Title: Chromospheres and coronae in the T Tauri stars.
Authors: Imhoff, C. L.; Giampapa, M. S.
1982NASCP2238..456I    Altcode: 1982NASCP2338..456I; 1982auva.nasa..456I
  The Tauri stars exhibit strong far ultraviolet emission lines of C
  II, III, IV; OI; Si II, III; IV; and sometimes N V and He II. Surface
  fluxes of the lines for several T Tauri stars were computed, drawing
  upon both International Ultraviolet Explorer observations and published
  spectra. The surface fluxes are quite high. The FUV lines together
  account for 0.1% of the stellar luminosity. These results indicate the
  presence of active relatively dense chromospheres. The Tauri stars
  showing very strong visual emission spectra exhibit weakened high
  temperature FUV lines of C IV and N V, as well as He II which may be
  produced by X-rays. In the same stars, no X-ray emission was detected
  with Einstein. Among all the T Tauri stars the X-ray luminosities are
  deficient by factors of 100 to 1000 compared to the FUV lines. It
  is argued that the X-ray flux has not been heavily absorbed by
  circumstellar gas, as has been previously suggested, but that the
  X-rays are truly underluminous, perhaps due to the stellar wind. It is
  suggested that the birth and development of the chromosphere and corona
  may be occurring during the T Tauri stage of protostellar evolution.

---------------------------------------------------------
Title: A preflare diminution in the quiescent flux of EQ Pegasi.
Authors: Giampapa, M. S.; Africano, J. L.; Klimke, A.; Parks, J.;
   Quigley, R. J.; Robinson, R. D.; Worden, S. P.
1982ApJ...252L..39G    Altcode:
  The occurrence of a remarkable flare event on EQ Peg is reported as
  recorded by high speed photometry in the Johnson U band: a stellar
  flare event is immediately preceded by a well-defined decline in
  the quiescent flux of the star. The U band flux decays to a minimum
  level that is 75% of the stellar quiescent flux, and the duration of
  the so-called negative flare event is 2.7 minutes. A description of
  the observation is presented and hypotheses are discussed that may
  eventually account for this phenomenon.

---------------------------------------------------------
Title: IUE observations of pre-main-sequence stars. I. MG II and CA
    II resonance line fluxes for T Tau stars.
Authors: Giampapa, M. S.; Calvet, N.; Imhoff, C. L.; Kuhi, L. V.
1981ApJ...251..113G    Altcode:
  IUE satellite and Lick 3 m reflector image tube scanner measurements
  of the Mg II and Ca II resonance lines in a sample of T Tauri stars
  are the basis of a discussion of the Mg II h and k line emission
  and the Ca II H and K line emission, within the context of stellar
  chromospheres. Corroborative evidence is presented for the chromospheric
  origin of these resonance lines, and chromospheric radiative loss rates
  in the Mg II and Ca II resonance lines are derived. It is found that
  the degree of nonradiative heating present in the outer atmospheres
  of T Tauri stars generally exceeds that of the RS CVn systems, as
  well as the dMe stars and other active chromospheric dwarfs, and it is
  inferred that the surfaces of such pre-main sequence stars are covered
  by regions similar to solar plages. The mean chromospheric electron
  density of T Tauri stars is determined as 10 to the 11th/cu cm.

---------------------------------------------------------
Title: High-resolution profiles of chromospheric lines in M dwarf
    stars.
Authors: Worden, S. P.; Schneeberger, T. J.; Giampapa, M. S.
1981ApJS...46..159W    Altcode:
  Forty-six hydrogen and sodium line profiles are presented for 17
  selected dwarf M and dwarf M emission line stars. These profiles,
  derived from echelle spectrograms, typically have 0.25 A spectral
  resolution. Most of the dMe stars show hydrogen emission lines with
  central reversals. Central emission features in the cores of the Na D
  lines are often observed, and the presence of these emission features
  is strongly correlated with hydrogen line emission.

---------------------------------------------------------
Title: Stellar model chromospheres. XII. High-resolution, absolute
    flux profiles of the CaII H and K lines in dMe and non-dMe stars.
Authors: Giampapa, M. S.; Worden, S. P.; Schneeberger, T. J.; Cram,
   L. E.
1981ApJ...246..502G    Altcode:
  We present 142 mÅ resolution spectra of the cores and wings of the
  Ca II H and K lines in three dMe and four comparison dwarf M stars,
  obtained with the KPNO 4 m echelle spectrograph and blue image
  tube. The narrow-band photometry of Willstrop and the Barnes and
  Evans relations for stellar angular diameters convert the observed
  relative flux to absolute surface flux units with an estimated
  uncertainty of ± 15 %. We derive chromospheric radiative loss rates
  in the H and K lines and discuss trends in these loss rates with
  effective temperature. Monochromatic surface fluxes are tabulated for
  different features in the H and K lines, and radiation temperatures
  are derived from the mean surface fluxes at K<SUB>1</SUB> and
  H<SUB>1</SUB>, respectively. We find T<SUB>R</SUB>(H<SUB>1</SUB>) &gt;
  T<SUB>R</SUB>(K<SUB>1</SUB>), consistent with partial redistribution
  theory. The T<SUB>R</SUB>(K<SUB>1</SUB>)/T<SUB>eff</SUB> ratio
  is higher in these M dwarfs than the giants studied in Paper X,
  and it is anomalously high for the dMe flare star YZ CMi. If
  T<SUB>R</SUB>(K<SUB>1</SUB>)/T<SUB>eff</SUB> is an empirical age
  indicator, then the result for YZ CMi implies that flare activity
  and youth are directly correlated, as has been suggested by other
  investigators. Moreover, the result implies that a high degree of
  nonradiative heating is present in the upper photospheres of dMe
  stars. Measurements of line widths at H<SUB>1</SUB> and K<SUB>1</SUB>
  are presented together with FWHM data for the H and K lines. We find
  that the scaling law proposed by Ayres generally agrees with the
  observed trend exhibited by the K<SUB>1</SUB> widths. We also discuss
  chromospheric radiative loss rates in the Hɛ line compared with loss
  rates in the H and K lines, and present corrected FWHM(K) widths and
  compare them to the widths predicted by the Wilson-Bappu relation as
  calibrated by Lutz.

---------------------------------------------------------
Title: High Resolution, Absolute Flux Profiles of the Mg II h and
    k Lines for T Tauri Stars
Authors: Giampapa, M. S.; Morossi, C.; Ramella, M.; Imhoff, C. L.
1981BAAS...13..811G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Mg II h and k lines in a sample of dMe and dM stars.
Authors: Giampapa, M. S.; Pornmann, P. L.; Ayres, T. R.; Linsky,
   J. L.; Worden, S. P.
1981NASCP2171..279G    Altcode: 1981uviu.nasa..279G; 1981NASCP3171..279G; 1980IUE80......279G
  Both Mg II h and k line fluxes are presented for a sample of 4 dMe and
  3 dM stars obtained with the IUE satellite in the long wavelength,
  low dispersion mode. The observed fluxes are converted to stellar
  surface flux units and the importance of chromospheric non radiative
  heating in this sample of M dwarf stars is intercompared. In addition,
  the net chromospheric radiative losses due to the Ca II H and K lines in
  those stars in the sample for which calibrated Ca II H and K line data
  exist are compared. Active region filling factors which likely give
  rise to the observed optical and ultraviolet chromospheric emission
  are estimated. The implications of the results for homogeneous, single
  component stellar model chromospheres analyses are discussed.

---------------------------------------------------------
Title: The ultraviolet variability of the T Tauri star RW Aurigae.
Authors: Imhoff, C. L.; Giampapa, M. S.
1981NASCP2171..185I    Altcode: 1981uviu.nasa..185I; 1980IUE80......185I; 1981NASCP3171..185I
  Between 1978 and 1979 the visible brightness of RW Aurigae increased
  by 0.9 mag. During this time (1) CIV and SiIV increased by factors
  of 2 to 4 while the lower ionization lines remained unchanged; (2)
  the fluorescent OI line increased by a factor of 8; (3) the shell
  spectrum changed from emission to absorption; and (4) the ultraviolet
  continuum brightened by 2.3 mag. On a time scale of a week the continuum
  varied by as much as 0.8 mag., but the MgII emission lines showed no
  variability over 10 percent. An active chromosphere, transition region,
  and envelope cooled by mass loss are hypothesized in order to explain
  the ultraviolet observations of RW Aur.

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Title: The Transition Regions &amp; Coronae of Solar-Type Stars
Authors: Giampapa, Mark S.
1981iue..prop..751G    Altcode:
  We propose to obtain low dispersion, high signal-to-noise, short
  wavelength spectra for a sample of solar-type stars for which X-ray
  data are available. The transition region pressures, as inferred from
  the short wavelength spectra to be obtained with the IUE satellite,
  will be compared to the values of the transition region pressures
  predicted by the scaling laws advanced by Rosner, Tucker and Vaiana
  (1978) and Golub et al. (1980) on the basis of HEAO-B soft X-ray
  observations. In addition, we will assess the energy balance in the
  outer atmospheres of solar-type stars by comparing the total transition
  region and chromospheric line luminosities to the X-ray luminosities
  for the stars considered in this proposal.

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Title: UV chromospheric and circumstellar diagnostic features among
    F supergiant stars.
Authors: Stencel, R. E.; Worden, S. P.; Giampapa, M. S.
1981NASCP2171..311S    Altcode: 1981NASCP3171..311S; 1980IUE80......311S; 1981uviu.nasa..311S
  A survey of F supergiant stars to evaluate the extension of
  chromospheric and circumstellar characteristics commonly observed
  in the slightly cooler G, K, and M supergiant is discussed. An
  ultraviolet survey was elected since UV features of Mg II and Fe II
  might persist in revealing outer atmosphere phenomena even among F
  supergiants. The encompassed spectral types F0 to G0, and luminosity
  classes Ib, Ia, and Ia-0. In addition, the usefulness of the emission
  line width-to-luminosity correlation for the G-M stars in both the Ca
  II and Mg II lines is examined.

---------------------------------------------------------
Title: High Dispersion, Long Wavelength Studies of T Tauri Stars
Authors: Giampapa, Mark S.
1981iue..prop..762G    Altcode:
  We propose to obtain high dispersion, high quality, long wavelength
  spectra as well as some low dispersion, short wavelength spectra for
  a sample of T Tauri stars. The data to be obtained in this program
  will be supplemented with ground-based, high spectral resolution
  optical observations to be acquired simultaneously with the IUE
  observations. These data will be used for a comprehensive study of the
  structure, energy balance, velocity fields and mass loss rates that
  characterize the atmospheres of T Tauri stars. More specifically,
  we will develop semi-empirical models for the chromospheres and
  transition regions of specific T Tauri stars in order to parameterize
  the atmospheres Of these pre-main sequence objects and to attempt to
  discover why the T Tauri stars do not obey the Wilson-Bappu relation.

---------------------------------------------------------
Title: IUE observations of the Mg II emission lines in T Tauri stars.
Authors: Imhoff, C. L.; Giampapa, M. S.
1980PASP...92..548I    Altcode:
  No abstract at ADS

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Title: The Chromospheres of M Dwarf Stars
Authors: Giampapa, M. S.; Worden, S. P.; Linsky, J. L.
1980BAAS...12..807G    Altcode:
  No abstract at ADS

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Title: The ultraviolet spectrum of the T Tau star RW Aur.
Authors: Imhoff, C. L.; Giampapa, M. S.
1980ApJ...239L.115I    Altcode:
  Ultraviolet spectra of the T Tauri star RW Aurigae have been obtained
  with the International Ultraviolet Explorer. Emission lines include
  Mg II, Fe II, Cr II, Si I, Si II, Si III, Si IV, C II, C IV, and
  L alpha. The spectrum roughly resembles the solar chromospheric
  spectrum, but the surface fluxes are 200 times greater. N V and He
  II appear to be absent, a possible indication of either an extended
  chromosphere cooled by mass loss or an optically thick, hot shocked
  region. The ultraviolet excess in RW Aur is strong, consistent with
  Balmer continuum emission. The observed continuum may be used to set
  limits on the type and amount of extinction affecting the star.

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Title: Emission measures derived from far ultraviolet spectra of T
    Tau stars.
Authors: Cram, L. E.; Giampapa, M. S.; Imhoff, C. L.
1980ApJ...238..905C    Altcode:
  Spectroscopic diagnostics based on UV emission line observations have
  been developed to study the solar chromosphere, transition region,
  and corona. The atmospheric properties that can be inferred from
  observations of total line intensities include the temperature, by
  identifying the ionic species present; the temperature distribution of
  the emission measure, from the absolute intensities; and the electron
  density of the source, from line intensity ratios sensitive to the
  electron density. In the present paper, the temperature distribution of
  the emission measure is estimated from observations of far UV emission
  line fluxes of the T Tauri stars, RW Aurigae and RU Lupi, made on the
  IUE. A crude estimate of the electron density of one star is obtained,
  using density-sensitive line ratios.

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Title: An Estimate of Active Region Filling Factors for Dme-Stars
    and Dm-Stars
Authors: Giampapa, M. S.
1980SAOSR.389..119G    Altcode: 1980csss....1..119G
  No abstract at ADS

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Title: The chromospheres of M dwarf stars
Authors: Giampapa, Mark Steven
1980PhDT.......127G    Altcode:
  No abstract at ADS

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Title: The chromospheres of M Dwarf Stars
Authors: Giampapa, Mark S.
1980cmds.book.....G    Altcode:
  No abstract at ADS

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Title: The Chromospheres of M Dwarf Stars.
Authors: Giampapa, M. S.
1980PhDT.........5G    Altcode:
  Single-component, homogeneous, quiescent semi-empirical model
  chromospheres are constructed, based upon high resolution,
  well-calibrated profiles of the Ca II K line in 3 dMe and 2 dM
  stars. The results of the atmospheric models inferred from the
  observed Ca II K line profiles reveal several systematic trends
  which characterize the chromospheres of M dwarf stars. In particular,
  high values of T min/Teff are deduced for the stars considered, thus
  indicating an unusually large degree of nonradiative heating present in
  the upper photospheres of M dwarf stars. Hence dissipation of mechanical
  energy is an important parameter in the control of the energy balance
  in the upper photospheres of M dwarf stars. The value of the lower
  chromospheric temperature gradient, dT/d log m, is similar for the
  M dwarf stars considered. Chromospheric K-line emission strength is
  most sensitive to the total amount of chromospheric material present
  within the approximate temperature range Tmin-6000K.

---------------------------------------------------------
Title: The Evolution of the Chromospheres and Transition Regions in
    Dwarf Stars
Authors: Giampapa, Mark S.
1980iue..prop..445G    Altcode:
  We propose to study the active chromosphere stars xi Boo A and 70
  Oph A. These are solar type stars which exhibit much larger levels
  of chromospheric activity than the sun. There are two complementary
  aspects of this proposal. Our first objective is to obtain high spectral
  resolution observations of upper chromospheric and transition region
  spectral diagnostics. These data will be used to model the quiescent
  states of these stars and compare their upper atmospheric structure to
  the sun and other quiet chromosphere G dwarf stars. Our second objective
  is to perform a coordinated optical, X-ray, radio, and IUE ultraviolet
  spectral monitoring of these two stars to study flare events. In
  particular we hope to observe flare events, model flare structure,
  and compare the derived physical conditions in stellar flares to solar
  events. We have recently observed extensive large magnetic fields
  on these stars, and we believe they exhibit frequent flares. We are
  confident that time resolved data needed to model the stellar flares is
  obtainable in the required spectral bands, including the IUE ultraviolet
  region. The results of these studies will improve our understanding
  of solar and stellar chromospheric and non-radiative phenomena.

---------------------------------------------------------
Title: IUE Observations of T. Tauri Stars
Authors: Imhoff, C. L.; Giampapa, M. S.
1979BAAS...11..681I    Altcode:
  No abstract at ADS

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Title: High Resolution Spectra of Stellar Flares
Authors: Worden, S. P.; Schneeberger, T. J.; Deluca, E.; Giampapa, M.
1979BAAS...11..628W    Altcode:
  No abstract at ADS

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Title: The Ca II H and K Lines in dMe and non-dMe Stars
Authors: Giampapa, M. S.; Worden, S. P.; Schneeberger, T. J.; Cram,
   L. E.
1979BAAS...11..625G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The effect of chromospheric activity on metallicity
    measurements.
Authors: Giampapa, M. S.; Gilliam, L. B.; Worden, S. P.
1979ApJ...229.1143G    Altcode:
  The intermediate band uvby-beta photometric system is used to observe
  solar active (plage) regions and quiescent regions in an effort
  to determine the effect of chromospheric activity on photometric
  metallicity measurements. It is found that the active regions appear
  metal deficient with respect to the quiet sun by approximately 35%.

---------------------------------------------------------
Title: Compact variable extragalactic objects and small-pitch-angle
    synchrotron theory.
Authors: Cocke, W. J.; Giampapa, M. S.; Pacholczyk, A. G.
1979ApJ...229..503C    Altcode:
  A small-pitch-angle synchrotron radiation model of luminous compact
  variable radio sources is applied to a large class of such objects. The
  model consists of a massive spinning object endowed with an extended
  magnetosphere. The electrons are accelerated near its surface by a
  strong electric field, spiral along the field lines, and lose their
  energy by the small-pitch-angle synchrotron process responsible for
  the observed centimeter and infrared radiation. The model adequately
  explains the observed variability of the majority of compact sources for
  (rest frame) frequencies greater than about 10 GHz. The model is not
  able to account for the variability of sources at lower frequencies,
  indicating clearly that an investigation of alternative radiation
  mechanisms or relativistic effects resulting from bulk motion is
  necessary.

---------------------------------------------------------
Title: A Survey of Astronomy Graduate Students
Authors: Giampapa, M. S.
1979AstQ....3....5G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Chromospheric emission lines in the red spectrum of AD
    Leonis. I. The nonflare spectrum.
Authors: Giampapa, M. S.; Linsky, J. L.; Schneeberger, T. J.; Worden,
   S. P.
1978ApJ...226..144G    Altcode:
  High-resolution red (5300-7300 A) spectra of the flare star AD Leonis
  were obtained with the Kitt Peak 4 m echelle spectrograph system
  at a spectral resolution of 0.22 A at Ha. A series of time-trailed
  plates with 5 hours integration in total were averaged together
  to obtain a representation of the star's nonflaring spectrum with
  high signal-to-noise ratio. The He i A5876 triplet line and A6678
  singlet line appear in emission with measured equivalent widths of
  0.312 + 0.016 A and 0.058 + 0.029 A, respectively. The corresponding
  triplet-to-singlet line flux ratio is 3.7, close to the ratio of the
  level statistical weights. We argue that the He i lines are not produced
  by recombination and cascade following photoionization by A &lt; 504
  A coronal photons, but are instead collisionally excited. We suggest
  that these lines are formed in a geometrically thin chromospheric layer
  at 20,000-50,000 K with a column density of nel 6 x 1018 . The sodium
  D emission lines (A5890, AS 896) are found to be stellar in origin,
  with measured FWHM of 0.7 A for both lines, and the Ha line has a
  FWHM of 1.4 A. No other chromospheric emission lines were found in
  this spectral region. Subject headings: stars: chromospheres - stars:
  emission-line - stars: flare - stars: individual

---------------------------------------------------------
Title: The Effects of Stellar Chromospheric Activity on Metallicity
    Measurements.
Authors: Giampapa, M. S.; Worden, S. P.
1978BAAS...10..458G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Application of the Small-Pitch Angle Synchrotron Theory to
    a Wide Class of Variable Compact Extragalactic Objects.
Authors: Cocke, W. J.; Giampapa, M. S.; Pacholczyk, A. G.
1978BAAS...10R.404C    Altcode:
  No abstract at ADS

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Title: On the polarization and mass of BL Lac objects.
Authors: Angel, J. R. P.; Boroson, T. A.; Adams, M. T.; Duerr, R.;
   Giampapa, M. S.; Gresham, M. S.; Gural, P. S.; Hubbard, E. N.; Kopriva,
   D. A.; Moore, R. L.; Peterson, B. M.; Schmidt, G. D.; Turnshek, D. A.;
   Wilkerson, M. S.; Zotov, N. V.; Maza, J.; Kinman, T. D.
1978bllo.conf..117A    Altcode: 1978blo..conf..117A
  Optical polarization measurements have been obtained for 12 BL Lac
  objects, including many repeated observations during a night. It
  is found that the shortest time scale for substantial changes in
  polarization is about 10 hours. Fluctuations with a 1-day characteristic
  time are common. This time is identified with the dynamical time
  scale of the most luminous material close to a black hole. It follows
  that the typical mass is about 2 billion solar masses. Observations
  over several years show that five out of 12 objects have a preferred
  orientation of position angle, perhaps defined by the angular-momentum
  vector of accreted material.

---------------------------------------------------------
Title: Chromospheric Emission Lines in the Quiescent Spectrum of
    the Flare Star AD Leo
Authors: Giampapa, M. S.; Linsky, J. L.; Schneeberger, T. J.; Worden,
   S. P.
1977BAAS....9..593G    Altcode:
  No abstract at ADS