Line-by-line opacity stellar model atmospheres

Author(s)
Denis Victorovich Shulyak, Vadim Tsymbal, Tanya A. Ryabchikova, Christian Stütz, Werner Wolfgang Weiss
Abstract

Modelling stellar atmospheres becomes increasingly demanding as more accurate observations draw a more complex picture of how real stars look like. What could be called a normal star becomes increasingly rare because of, e.g., significant deviations from the classical solar abundance pattern and clear evidence for stratification of elements in the atmospheres as well as surface inhomogeneities (spots) causing further severe deviations from "standard" atmospheres. We describe here a new code for calculating LIE plane-parallel stellar model atmospheres for early and intermediate type of stars which has been written in Compaq Fortran 95 and can be compiled for Windows and Linux/UNIX computer platforms. The code is based on modified ATLAS9 subroutines (Kurucz) and on spectrum synthesis codes written by V. Tsymbal with the main modifications of input physics concerning the block for opacity calculation. Each line contributing to opacity is taken into account for modelling the atmosphere, similar to synthetic spectrum calculations. This approach, which we call the line-by-line (LL) technique, avoids problems resulting from statistical methods (ODF, OS) and allows to calculate complex models with abundances which are not simply scaled from a standard pattern (usually the solar abundances) and which can be even depth dependent. Stratification is considered in this context as an empirical input parameter which has to be derived from observations. Due to the implemented numerical methods, mainly in the opacity calculation module, our code produces model atmospheres with modern PCs in a time comparable to that required by classical routines.

Organisation(s)
Department of Astrophysics
External organisation(s)
Russian Academy of Sciences
Journal
Astronomy & Astrophysics
Volume
428
Pages
993-1000
No. of pages
8
ISSN
0004-6361
Publication date
2004
Peer reviewed
Yes
Austrian Fields of Science 2012
103003 Astronomy
Portal url
https://ucrisportal.univie.ac.at/en/publications/6a819276-8bbb-4709-ae09-5fee6df5870f