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We present the extension of our NextGen model atmosphere grid to the regime of giant stars. The input physics of the models presented here is nearly identical to the NextGen dwarf atmosphere models, however spherical geometry is used…

Astrophysics · Physics 2009-10-31 Peter H. Hauschildt , France Allard , Jason Ferguson , E. Baron , David R. Alexander

We have calculated a grid of more than 700 model atmospheres valid for a wide range of parameters encompassing the coolest known M~dwarfs, M~subdwarfs and brown dwarf candidates: $1500\le \teff \le 4000\,$K, $3.5\le \log(g)\le 5.5$, and…

Astrophysics · Physics 2009-10-28 France Allard , Peter H. Hauschildt

We have constructed a grid of about 10,000 spherically symmetric and plane-parallel models with the MARCS program, and make it available for public use. Parameter ranges are: Teff=2500 to 8000 K, log g =log(GM/R2)= -1 to 5 (cgs) with…

A new grid of detailed atmosphere model spectra for hot and moderately cool subdwarf stars is presented. High-resolution spectra and synthetic photometry are calculated in the range from 1000{\AA} to 10,000{\AA} using Non-LTE fully…

Solar and Stellar Astrophysics · Physics 2021-10-07 Thayse A. Pacheco , Marcos P. Diaz , Ronaldo S. Levenhagen , Paula R. T. Coelho

S-type stars are late-type giants whose atmosphere is enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. A large…

We test state-of-the-art model atmospheres for young very low-mass stars and brown dwarfs in the infrared, by comparing the predicted synthetic photometry over 1.2-24 {\mu}m to the observed photometry of M-type spectral templates in…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jonathan Tottle , Subhanjoy Mohanty

We have constructed a comprehensive grid of 690 metal line-blanketed, NLTE, plane-parallel, hydrostatic model atmospheres for the basic parameters appropriate to O-type stars. The OSTAR2002 grid considers 12 values of effective…

Astrophysics · Physics 2009-11-07 Thierry Lanz , Ivan Hubeny

We present our NextGen Model Atmosphere grid for low mass stars for effective temperatures larger than $3000\K$. These LTE models are calculated with the same basic model assumptions and input physics as the VLMS part of the NextGen grid so…

Astrophysics · Physics 2008-11-26 Peter H. Hauschildt , France Allard , E. Baron

A grid of ATLAS9 model atmospheres has been computed, spanning 3500 K <= T_eff <= 8000 K, 0.0 <= log g <= 5.0, -4.0 <= [M/H] <= 0.0, and -0.8 < [alpha/Fe] <= +1.2. These parameters are appropriate for stars in the red giant branch, subgiant…

Solar and Stellar Astrophysics · Physics 2011-10-26 Evan N. Kirby

We have computed a grid of high resolution synthetic spectra for cool stars (2500<Teff<6000 K) in the wavelength range 6000 -- 10200A, by employing an updated line list of atomic and molecular lines, together with state-of-the-art model…

Astrophysics · Physics 2009-10-30 Ricardo P. Schiavon , Beatriz Barbuy

We derive the stellar parameters of a sample of Galactic early-O type stars by analysing their UV and Far-UV spectra from FUSE (905-1187A), IUE, HST-STIS and ORFEUS (1200-2000A). The data have been modeled with spherical, hydrodynamic,…

Astrophysics · Physics 2009-11-10 Miriam Garcia , Luciana Bianchi

With a uniform VLT SINFONI data set of nine targets, we have developed an empirical grid of J,H,K spectra of the atmospheres of objects estimated to have very low substellar masses of \sim5-20 MJup and young ages of \sim1-50 Myr. Most of…

Earth and Planetary Astrophysics · Physics 2015-06-03 J. Patience , R. R. King , R. J. De Rosa , A. Vigan , S. Witte , E. Rice , Ch. Helling , P. Hauschildt

Evolutionary and atmospheric models have become available for young ultralow-mass objects. These models are being used to determine fundamental parameters from observational properties. TiO bands are used to determine effective temperatures…

Astrophysics · Physics 2009-11-11 Ansgar Reiners

We present an update of the grid of detailed atmosphere models and homogeneous synthetic spectra for hot, high-gravity subdwarf stars. High-resolution spectra and synthetic photometry were calculated in the wavelength range 1,000 \r{A} -…

Solar and Stellar Astrophysics · Physics 2023-07-18 Thayse A. Pacheco , Ronaldo S. Levenhagen , Marcos P. Diaz , Paula R. T. Coelho

We present a comparison of low-resolution spectra of 60 stars covering the whole M-dwarf sequence. Using the most recent PHOENIX BT-Settl stellar model atmospheres (see paper by F. Allard, in this book) we do a first quantitative compari-…

Solar and Stellar Astrophysics · Physics 2011-02-09 C. Reyle , A. S. Rajpurohit , M. Schultheis , F. Allard

We present a database of 45,000 atmospheric models (which will become 80,000 models by the end of the project) with stellar masses between 9 and 120 M$_{\odot}$, covering the region of the OB main sequence and W-R stars in the H-R diagram.…

We rediscuss the temperature of O dwarfs based on new non-LTE line blanketed atmosphere models including stellar winds computed with the CMFGEN code of Hillier & Miller (1998). Compared to the latest calibration of Vacca et al. (1996), the…

Astrophysics · Physics 2010-04-29 F. Martins , D. Schaerer , D. J. Hillier

We calculate a grid of spherically symmetric OB stellar atmospheres at low metallicities, including both non-local thermodynamic equilibrium (NLTE) and metal line blanketing effects. This is done to assess the uncertainties in helium…

Astrophysics · Physics 2009-10-31 S. L. Pistinner , P. H. Hauschildt , D. Eichler , E. A. Baron

We compare the structures of model atmospheres and synthetic spectra calculated using different line lists for TiO and water vapor. We discuss the effects of different line list combinations on the model strutures and spectra for both dwarf…

Astrophysics · Physics 2010-05-17 France Allard , Peter H. Hauschildt , David Schwenke

We present the Stagger-grid, a comprehensive grid of time-dependent, 3D hydrodynamic model atmospheres for late-type stars with realistic treatment of radiative transfer, covering a wide range in stellar parameters. This grid of 3D models…

Solar and Stellar Astrophysics · Physics 2015-06-15 Z. Magic , R. Collet , M. Asplund , R. Trampedach , W. Hayek , A. Chiavassa , R. F. Stein , Å. Nordlund
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