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Massive sets of stellar spectroscopic observations are rapidly becoming available and these can be used to determine the chemical composition and evolution of the Galaxy with unprecedented precision. One of the major challenges in this…

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.…

Non-local Thermodynamic Equilibrium (NLTE) calculations of hot white dwarf (WD) model atmospheres are the cornerstone of modern flux calibrations for the Hubble Space Telescope (HST) and for the CALSPEC database. These theoretical spectral…

太阳与恒星天体物理 · 物理学 2020-06-17 Ralph Bohlin , Ivan Hubeny , Thomas Rauch

We describe a self-consistent spectrum analysis technique employing non-LTE line formation, which allows precise atmospheric parameters of massive stars to be derived: 1sigma-uncertainties as low as ~1% in effective temperature and…

太阳与恒星天体物理 · 物理学 2015-03-17 Maria-Fernanda Nieva , Norbert Przybilla

The study of massive stars in different metallicity environments is a central topic of current stellar research. The spectral analysis of massive stars requires adequate model atmospheres. The computation of such models is difficult and…

太阳与恒星天体物理 · 物理学 2019-01-16 R. Hainich , V. Ramachandran , T. Shenar , A. A. C. Sander , H. Todt , D. Gruner , L. M. Oskinova , W. -R. Hamann

We provide here a significant extension of the NuGrid Set 1 models in mass coverage and toward lower metallicity, adopting the same physics assumptions. The combined data set now includes the initial masses M/Msun = 1, 1.65, 2, 3, 4, 5, 6,…

太阳与恒星天体物理 · 物理学 2018-09-05 C. Ritter , F. Herwig , S. Jones , M. Pignatari , C. Fryer , R. Hirschi

In this talk we review the basic assumptions and physics covered by classical 1D LTE model atmospheres. We will focus on ATLAS and MARCS models of F-G-K stars and describe what resources are available through the web, both in terms of codes…

太阳与恒星天体物理 · 物理学 2011-09-06 Piercarlo Bonifacio , Elisabetta Caffau , Hans-Guenter Ludwig , Matthias Steffen

Non-local thermodynamical equilibrium (NLTE) line formation for Mg I and Mg II lines is considered in classical 1D-LTE model atmospheres of the Sun and 17 stars with reliable atmospheric parameters and in a broad range of spectral types:…

太阳与恒星天体物理 · 物理学 2018-10-31 Sofya Alexeeva , Tatiana Ryabchikova , Lyudmila Mashonkina , Shaoming Hu

The current status of NLTE model atmosphere calculations of A type stars is reviewed. During the last decade the research has concentrated on solving the restricted NLTE line formation problem for trace elements assuming LTE model…

天体物理学 · 物理学 2007-05-23 Jiri Kubat , Daniela Korcakova

We performed extensive tests of the accuracy of atmospheric parameter determination for FGK stars based on the spectrum fitting procedure Spectroscopy Made Easy (SME). Our stellar sample consists of 13 objects, including the Sun, in the…

太阳与恒星天体物理 · 物理学 2016-01-27 T. Ryabchikova , N. Piskunov , Yu. Pakhomov , V. Tsymbal , A. Titarenko , T. Sitnova , S. Alexeeva , L. Fossati , L. Mashonkina

Models of stellar spectra are necessary for interpreting light from individual stars, planets, integrated stellar populations, nebulae, and the interstellar medium. We provide a comprehensive and homogeneous collection of synthetic spectra…

太阳与恒星天体物理 · 物理学 2018-10-10 Carlos Allende Prieto , Lars Koesterke , Ivan Hubeny , Manuel A. Bautista , Paul S. Barklem , Sultana N. Nahar

In the last decades, stellar atmosphere models have become a key tool in understanding massive stars. Applied for spectroscopic analysis, these models provide quantitative information on stellar wind properties as well as fundamental…

太阳与恒星天体物理 · 物理学 2017-11-15 Andreas A. C. Sander

We present results of our calculations of NLTE model stellar atmospheres for hot Population III stars composed of hydrogen and helium. We use our own computer code for calculation of spherically symmetric NLTE model atmospheres in…

太阳与恒星天体物理 · 物理学 2014-06-16 Jiří Kubát

The precise analysis of properties of planetary nebulae is strongly dependent on good models for the stellar ionizing spectrum. Observations in the UV - X-ray wavelength range as well as NLTE model atmosphere calculations of spectra of…

天体物理学 · 物理学 2009-11-07 Thomas Rauch

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…

天体物理学 · 物理学 2009-10-28 France Allard , Peter H. Hauschildt

Analyses of stellar spectra, stellar populations, and transit light curves rely on grids of synthetic spectra and center-to-limb variations (limb darkening) from model stellar atmospheres. Extensive model grids from PHOENIX, a generalized…

太阳与恒星天体物理 · 物理学 2025-05-28 Peter H. Hauschildt , T. Barman , E. Baron , J. P. Aufdenberg , A. Schweitzer

Aims. We compare the predictions of evolutionary models for early-type stars with atmospheric parameters, projected rotational velocities and nitrogen abundances estimated for a sample of Be-type stars. Our targets are located in 4 fields…

太阳与恒星天体物理 · 物理学 2015-05-30 P. R. Dunstall , I. Brott , P. L. Dufton , D. J. Lennon , C. J. Evans , S. J. Smartt , I. Hunter

Present observational techniques provide stellar spectra with high resolution at a high signal-to-noise ratio over the complete wavelength range -- from the far infrared to the X-ray. NLTE effects are particularly important for hot stars,…

天体物理学 · 物理学 2007-05-23 Thomas Rauch , Jochen L. Deetjen , Stefan Dreizler , Klaus Werner

$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R)…

太阳与恒星天体物理 · 物理学 2020-11-18 J. Zsargo , C. R. Fierro-Santillan , J. Klapp , A. Arrieta , L. Arias , J. M. Valencia , L. Di G. Sigalotti , M. Hareter , R. E. Puebla

Precise fundamental atmospheric stellar parameters and abundance determination of individual elements in stars are important for all stellar population studies. Non-Local Thermodynamic Equilibrium (Non-LTE; hereafter NLTE) models are often…

太阳与恒星天体物理 · 物理学 2023-03-15 Yangyang Li , Rana Ezzeddine