New extended atomic data in cool star model atmospheres

Using Kurucz's new iron data in MAFAGS-OS models

¹ Max Planck Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany e-mail: frank@grupp-astro.de
² Universitäts Sternwarte München, Scheinerstr. 1, 81679 München, Germany e-mail: frank@grupp-astro.de
³ Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA e-mail: rkurucz@cfa.harvard.edu
⁴ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China e-mail: tan@bao.ac.cn

Received: 8 April 2009
Accepted: 14 June 2009

Abstract

Context. Cool star model atmospheres are a common tool for the investigation of stellar masses, ages and elemental abundance composition. Theoretical atmospheric models strongly depend on the atomic data used when calculating them.

Aims. We present the changes in flux and temperature stratification when changing from iron data computed by R.L. Kurucz in the mid 90s to the Kurucz 2009 iron computations.

Methods. MAFAGS-OS opacity sampling atmospheres were recomputed with Kurucz 2009 iron atomic data as implemented in the VALD database by Ryabchikova. Temperature stratification and emergent flux distribution of the new version, called MAFAGS-OS9, is compared to the former version and to solar flux measurements.

Results. Using the Kurucz line lists converted into the VALD format and new bound-free opacities for Mg i and Al i leads to changes in the solar temperature stratification by not more than 28 K. At the same time, the calculated solar flux distribution shows significantly better agreement between observations and theoretical solar models. 
These changes in the temperature stratification of the corresponding models are small, but nevertheless of a magnitude that affects stellar parameter determinations and abundance analysis.