Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

D. Carollo*, D. Koester, A. Spagna, M. G. Lattanzi, S. T. Hodgkin

*Corresponding author for this work

Research output: Contribution to journalLetter

11 Citations (Scopus)
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Abstract

A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UBJVRFINJHK) and a low resolution spectrum (3500 < λ < 7500 Å) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate Teff ≃ 5120 ± 200 K and log[C/He] ≃ -5.8 ± 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C2 to C2H molecules around Teff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.

Original languageEnglish
JournalAstronomy and Astrophysics
Volume400
Issue number1
Publication statusPublished - Mar 2003

Bibliographical note

Copyright ESO 2003. First published in Astronomy and Astrophysics, Vol. 400, No. 1, published by EDP Sciences. The original publication is available at http://dx.doi.org/10.1051/0004-6361:20030132

Keywords

  • Stars: Individual: GSC2U J131147.2+292348
  • Stars: Kinematics
  • Techniques: Spectroscopic
  • White dwarfs

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