Theoretical UBVRI colors of iron core white dwarfs

¹ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
² Department of Physics, Center for Theoretical Physics and Center for Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
³ Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland

Corresponding author: M. Pietrachowicz, pietrach@tryton.astrouw.edu.pl

Received: 31 October 2002
Accepted: 30 July 2003

Abstract

We explore photometric properties of hypothetical iron core white dwarfs and compute their expected colors in UBVRI Johnson broadband system. Atmospheres of iron core WDs in this paper consist of pure iron covered by a pure hydrogen layer of an arbitrary column mass. LTE model atmospheres and theoretical spectra are calculated on the basis of Los Alamos TOPS opacities and the equation of state from the OPAL project, suitable for nonideal Fe and H gases. We have also computed UBVRI colors of the models and determined an area on the vs. and vs. planes, occupied by both pure Fe, and pure H model atmospheres of WD stars. Finally, we search for iron core white dwarf candidates in the available literature.