EDP Sciences
Free access
Volume 412, Number 3, December IV 2003
Page(s) 837 - 848
Section Formation and evolution of planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20031307

A&A 412, 837-848 (2003)
DOI: 10.1051/0004-6361:20031307

Theoretical UBVRI colors of iron core white dwarfs

J. Madej1, M. Pietrachowicz1, P. C. Joss2, A. Majczyna3, A. Rózanska3 and M. Nalezyty1

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

(Received 31 October 2002 / Accepted 30 July 2003 )

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 B-V vs. U-B and B-V vs. V-I 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.

Key words: stars: atmospheres -- stars: white dwarfs -- stars: fundamental parameters

Offprint request: M. Pietrachowicz, pietrach@tryton.astrouw.edu.pl

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