Title: On the nature of spectral features in peculiar DQ white dwarfs
Abstract: view Abstract Citations (60) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Nature of the Spectral Features in Peculiar ``DQ'' White Dwarfs Schmidt, Gary D. ; Bergeron, P. ; Fegley, Bruce Abstract Spectropolarimetric measurements are presented for the DQ white dwarfs ESO 439-162, LHS 1126, and G225-68, whose spectroscopic features in the optical have been interpreted in the past as pressure-shifted or magnetically shifted C2 Swan bands. The results convincingly demonstrate that none of these objects is strongly magnetic, with upper limits of 30, 3, and 2 MG respectively. Since Bergeron et al. (B 94) have recently ruled out the pressure-shift interpretation for LHS 1126 as well, we discuss alternative physical mechanisms for displacing the Swan bands. Although possibilities for explaining the observed shifts may exist, a comparison of the optical spectra (and that of a similar DQ star, LP 77-57) indicates that the locations and shapes of the profiles in all four objects are virtually identical. This last result suggests instead that a different molecular species could be responsible. A detailed chemical equilibrium analysis of H/He/C mixtures under the physical conditions encountered in the atmospheres of these peculiar objects reveals that C2H is a molecule preferentially formed in the photospheric regions. The nature and evolution of these objects are discussed. Publication: The Astrophysical Journal Pub Date: April 1995 DOI: 10.1086/175524 Bibcode: 1995ApJ...443..274S Keywords: Polarization; Spectrum Analysis; Swan Bands; White Dwarf Stars; Abundance; Astronomical Polarimetry; Astronomical Spectroscopy; Carbon Compounds; Frequency Shift; Helium; Hydrogen; Stellar Magnetic Fields; Visible Spectrum; Astrophysics; POLARIZATION; STARS: ABUNDANCES; STARS: ATMOSPHERES; STARS: MAGNETIC FIELDS; STARS: WHITE DWARFS full text sources ADS | data products SIMBAD (9)
Publication Year: 1995
Publication Date: 1995-04-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 51
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