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MODELING THE NEAR-UV BAND OF GK STARS. II. NON-LTE MODELS
- Source :
- The Astrophysical Journal. 747:143
- Publication Year :
- 2012
- Publisher :
- American Astronomical Society, 2012.
-
Abstract
- We present a grid of atmospheric models and synthetic spectral energy distributions (SEDs) for late-type dwarfs and giants of solar and 1/3 solar metallicity with many opacity sources computed in self-consistent Non-Local Thermodynamic Equilibrium (NLTE), and compare them to the LTE grid of Short & Hauschildt (2010) (Paper I). We describe, for the first time, how the NLTE treatment affects the thermal equilibrium of the atmospheric structure (T(tau) relation) and the SED as a finely sampled function of Teff, log g, and [A/H] among solar metallicity and mildly metal poor red giants. We compare the computed SEDs to the library of observed spectrophotometry described in Paper I across the entire visible band, and in the blue and red regions of the spectrum separately. We find that for the giants of both metallicities, the NLTE models yield best fit Teff values that are ~30 to 90 K lower than those provided by LTE models, while providing greater consistency between \log g values, and, for Arcturus, Teff values, fitted separately to the blue and red spectral regions. There is marginal evidence that NLTE models give more consistent best fit Teff values between the red and blue bands for earlier spectral classes among the solar metallicity GK giants than they do for the later classes, but no model fits the blue band spectrum well for any class. For the two dwarf spectral classes that we are able to study, the effect of NLTE on derived parameters is less significant.
- Subjects :
- Thermal equilibrium
Physics
010504 meteorology & atmospheric sciences
Atmospheric models
Opacity
Thermodynamic equilibrium
Metallicity
Astronomy and Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Astrophysics
Stellar classification
01 natural sciences
Stars
Space and Planetary Science
0103 physical sciences
Arcturus
Astrophysics::Solar and Stellar Astrophysics
Astrophysics::Earth and Planetary Astrophysics
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 15384357 and 0004637X
- Volume :
- 747
- Database :
- OpenAIRE
- Journal :
- The Astrophysical Journal
- Accession number :
- edsair.doi...........ac6398a755e397d959c06816f8c1fe80