Hot DQ White Dwarfs: Something Different
نویسندگان
چکیده
منابع مشابه
Follow-up Observations of the Second and Third Known Pulsating Hot Dq White Dwarfs
We present follow-up time-series photometric observations that confirm and extend the results of the significant discovery made by Barlow et al. (2008) that the Hot DQ white dwarfs SDSS J220029.08−074121.5 and SDSS J234843.30−094245.3 are luminosity variable. These are the second and third known members of a new class of pulsating white dwarfs, after the prototype SDSS J142625.71+575218.3 (Mont...
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Context. Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of the SDSS project. There exist nine of them, out of a total of several thousands white dwarfs spectroscopically identified. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible with pulsation g-modes. Aims. Here, we pres...
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We present an analysis of spectroscopic and photometric observations of cool DQ white dwarfs based on improved model atmosphere calculations. In particular , we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz, and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We...
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We present a phenomenological study of highly ionised, non-photospheric absorption features in high spectral resolution vacuum ultraviolet spectra of 23 hot DA white dwarfs. Prior to this study, four of the survey objects (Feige 24, REJ 0457-281, G191B2B and REJ 1614-085) were known to possess these features. We find four new objects with multiple components in one or more of the principal reso...
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We have analyzed FUSE observations of six hot white dwarf stars: four DA white dwarfs with Teff >∼ 45 000 K, the DAO Feige 55 (Teff ≈ 55 000 K), and the DA CD−38◦ 10980 (Teff ≈ 24 000 K). Photospheric lines from Si IV, PV, and S VI can be observed in the majority of the five hotter objects. Feige 55 shows also several other heavier elements. The measured abundances agree only partly with the pr...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2008
ISSN: 0004-637X,1538-4357
DOI: 10.1086/589855