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.

arXiv commentAccepted for publication in A&A Letters, 4 pages, 2 figures

Cited by in corpus (7)

• The Second-Generation Guide Star Catalog: Description and Properties
• Detailed Spectroscopic and Photometric Analysis of DQ White Dwarfs
• An Initial Survey of White Dwarfs in the Sloan Digital Sky Survey
• Spectroscopic Identification of Cool White Dwarfs in the Solar Neighbourhood
• New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5<mu<2.0 arcsec/yr at High Galactic Latitudes
• The GSC-II-based survey of ancient cool white dwarfs I. The sample of spectroscopically confirmed WDs
• Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348