SPECTROSCOPIC ANALYSIS OF THE WHITE DWARF KUV 02196+2816: A NEW UNRESOLVED DA+DB DEGENERATE BINARY

Journal Article · Sun May 10 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/696/2/1461; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21300680

Limoges, M -M; Bergeron, P; Dufour, Pierre ^[1]

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1. Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)

A spectroscopic analysis of the DBA (or DAB) white dwarf KUV 02196+2816 is presented. The observed hydrogen- and helium-line profiles are shown to be incompatible with model spectra calculated under the assumption of a homogeneous hydrogen and helium chemical composition. In contrast, an excellent fit to the optical spectrum of KUV 02196+2816 can be achieved if the object is interpreted as an unresolved double degenerate composed of a hydrogen-line DA star and a helium-line DB star. The atmospheric parameters obtained from the best fit are T {sub eff} = 27170 K and log g = 8.09 for the DA star, T {sub eff} = 36340 K and log g = 8.09 for the DB star, which implies that the total mass of the system (M {approx} 1.4 M {sub sun}) is very close to the Chandrasekhar limit. Moreover, the effective temperature of the DB stars lies well within the so-called DB gap where very few bright DB stars are found. The implications of this discovery with respect to the DAB and DBA spectral classes and to the evolution of double-degenerate binaries are discussed.

• OSTI ID: 21300680
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 696; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
CHEMICAL COMPOSITION
HELIUM
HYDROGEN
MASS
SPECTRA
STAR EVOLUTION
WHITE DWARF STARS