Discovery of a peculiar DQ white dwarf
Abstract
We report the discovery of a new carbon rich white dwarf that was identified during a proper motion survey for cool white dwarfs based on photographic material used for the construction of the Guide Star Catalog II. Its large proper motion (0.48 arcsec/yr) and faint apparent magnitude (V = 18.7) suggest a nearby object of low luminosity. A low-resolution spectrum taken with the William Herschel Telescope clearly shows strong C2 Deslandres-d'Azambuja and Swan bands, which identify the star as a DQ white dwarf. The strength of the Deslandres-d'Azambuja bands and the depression of the continuum in the Swan-band region are signs of enhanced carbon abundance for the given Teff. Comparison of our spectrophotometric data to published synthetic spectra suggests 6000 K < Teff < 8000 K although further analysis with specialized synthetic models appear necessary to derive both Teff and chemical composition. Finally, the range of spatial velocity estimated for this object makes it a likely member of the halo or thick disk population.
Keywords
Cite
@article{arxiv.astro-ph/0208479,
title = {Discovery of a peculiar DQ white dwarf},
author = {D. Carollo and S. T. Hodgkin and A. Spagna and R. L. Smart and M. G. Lattanzi and B. J. McLean and D. J. Pinfield},
journal= {arXiv preprint arXiv:astro-ph/0208479},
year = {2009}
}
Comments
Accepted for publication in A&A Letters, 4 pages, 2 figures