Discovery of a peculiar DQ white dwarf

D. Carollo*, S. T. Hodgkin, A. Spagna, R. L. Smart, M. G. Lattanzi, B. J. McLean, D. J. Pinfield

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Citations (Scopus)

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 (μ ≃ 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.

Original languageEnglish
JournalAstronomy and Astrophysics
Volume393
Issue number3
Publication statusPublished - Oct 2002

Bibliographical note

Copyright ESO 2002. First published in Astronomy and astrophysics, Vol. 393 and No. 3, published by EDP Sciences. The original publication is available at http://dx.doi.org/10.1051/0004-6361:20021130

Keywords

  • Astrometry
  • Stars: carbon
  • Stars: individual: GSC2U J131147.2+292348
  • Stars: kinematics
  • Techniques: spectroscopic
  • White dwarfs

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