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We compute model atmospheres and emergent spectra for low field (B<10^10 G) neutron stars, using new opacity and equation of state data from the OPAL project. These computations, incorporating improved treatments of flux transport and…

天体物理学 · 物理学 2009-10-28 Mohan Rajagopal , Roger Romani

LHS1070 is a nearby multiple system of low mass stars. It is an important source of information for probing the low mass end of the main sequence, down to the hydrogen-burning limit. The primary of the system is a mid-M dwarf and two…

太阳与恒星天体物理 · 物理学 2015-06-11 A. S. Rajpurohit , C. Reyle , M. Schultheis , Ch. Leinert , F. Allard , D. Homeier , T. Ratzka , P. Abraham , B. Moster , S. Witte , N. Ryde

Accurately known stellar lithium abundances may be used to shed light on a variety of astrophysical phenomena such as Big Bang nucleosynthesis, radial migration, ages of stars and stellar clusters, and planet engulfment events. We present a…

太阳与恒星天体物理 · 物理学 2020-10-30 E. Wang , T. Nordlander , M. Asplund , A. M. Amarsi , K. Lind , Y. Zhou

Large-scale stellar surveys, such as SDSS-V, 4MOST, WEAVE, and PLATO, require accurate atmospheric models and synthetic spectra of stars for accurate analyses of fundamental stellar parameters and chemical abundances. The primary goal of…

太阳与恒星天体物理 · 物理学 2024-07-15 Philipp Eitner , Maria Bergemann , Richard Hoppe , Åke Nordlund , Bertrand Plez , Jonas Klevas

We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars, and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples…

太阳与恒星天体物理 · 物理学 2015-06-11 Gregory R. Ruchti , Maria Bergemann , Aldo Serenelli , Luca Casagrande , Karin Lind

We present a grid of optical (3200--7200 \AA) synthetic spectra calculated with Tlusty/Synspec. The new NLTE model atmospheres include the most recent hydrogen Stark broadening profiles; were calculated in opacity sampling and limited to…

太阳与恒星天体物理 · 物理学 2013-08-02 Peter Nemeth , Roy Østensen , Pier-Emmanuel Tremblay , Ivan Hubeny

The measurement of atmospheric parameters is fundamental for scientific research using stellar spectra. The Chinese Space Station Telescope (CSST), scheduled to be launched in 2024, will provide researchers with hundreds of millions of…

太阳与恒星天体物理 · 物理学 2024-08-21 JiaRui Rao , HaiLiang Chen , JianPing Xiong , LuQian Wang , YanJun Guo , JiaJia Li , Chao Liu , ZhanWen Han , XueFei Chen

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,…

天体物理学 · 物理学 2009-11-10 Miriam Garcia , Luciana Bianchi

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-…

太阳与恒星天体物理 · 物理学 2011-02-09 C. Reyle , A. S. Rajpurohit , M. Schultheis , F. Allard

In this paper we investigate statistical equilibrium of Ti in the atmospheres of late-type stars. The Ti I/Ti II level populations are computed with available experimental atomic data, except for photoionization and collision induced…

太阳与恒星天体物理 · 物理学 2015-05-20 Maria Bergemann

Context. The modeling of stellar spectra of flux standards observed by the Hubble and James Webb space telescopes requires a large synthetic spectral library that covers a wide atmospheric parameter range. Aims. The aim of this paper is to…

The surface gravities of cool (Teff < 13,000 K) hydrogen-atmosphere DA white dwarfs, determined from spectroscopic analyses, are found to be significantly higher than the canonical value of log g ~ 8 expected for these stars. It was…

太阳与恒星天体物理 · 物理学 2015-05-28 P. -E. Tremblay , H. -G. Ludwig , M. Steffen , P. Bergeron , B. Freytag

We present a LTE model atmosphere analysis of the medium and long wavelength spectrum of the cool DO white dwarf HD149499B. This observation in the spectral range 230-700 A supplements a previous analysis of an ORFEUS spectrum between 912…

天体物理学 · 物理学 2007-05-23 S. Jordan , R. Napiwotzki , D. Koester , T. Rauch

We present new evolutionary synthesis models for Single Stellar Populations covering a wide range in age and metallicity. The most important difference with existing models is the use of NLTE atmosphere models for the hot stars (O, B, WR,…

天体物理学 · 物理学 2007-11-21 M. Mollá , M. L. García-Vargas , Alessandro Bressan , Pedro Gómez-Alvarez

There is growing observational and theoretical evidence suggesting that atmospheric escape is a key driver of planetary evolution. Commonly, planetary evolution models employ simple analytic formulae (e.g., energy limited escape) that are…

Very massive stars (VMS) dominate the light of young stellar populations and are sources of intense stellar feedback. Their evolution is mainly driven by strong wind mass loss, yet current evolution models make simplistic assumptions on…

We present the first grid of 3D simulations for the pure-helium atmospheres of DB white dwarfs. The simulations were computed with the CO5BOLD radiation-hydrodynamics code and cover effective temperatures and surface gravities between 12000…

太阳与恒星天体物理 · 物理学 2018-09-05 E. Cukanovaite , P. -E. Tremblay , B. Freytag , H. -G. Ludwig , P. Bergeron

We determine Mg abundances in 6 Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally- and spatially-averaged 3D model atmospheres (<3D>). The stars cover a range of Teff from 4700…

太阳与恒星天体物理 · 物理学 2017-09-27 Maria Bergemann , Remo Collet , Anish M. Amarsi , Mikhail Kovalev , Gregory Ruchti , Zazralt Magic

We investigate NLTE effects for magnesium and calcium in the atmospheres of late-type giant and supergiant stars. The aim of this paper is to provide a grid of NLTE/LTE equivalent width ratios W/W* of Mg and Ca lines for the following range…

太阳与恒星天体物理 · 物理学 2015-05-30 Thibault Merle , Frédéric Thévenin , Bernard Pichon , Lionel Bigot

We present calculations illustrating the potential of gravitational microlensing to discriminate between classical models of stellar surface brightness profiles and the recently computed ``Next Generation'' models of Hauschildt et al. These…

天体物理学 · 物理学 2009-11-07 H. M. Bryce , M. A. Hendry , D. Valls-Gabaud