Double Degenerates among DA white dwarfs

Abstract

view Abstract Citations (120) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Double Degenerates among DA White Dwarfs Bragaglia, Angela ; Greggio, Laura ; Renzini, Alvio ; D'Odorico, Sandro Abstract The results of a spectroscopic survey of catalog white dwarfs in search of radial velocity variations indicative of a binary motion are reported. In a sample of 54 DA white dwarfs, one Double Degenerate (DD) system with a period of 1.15 days (the shortest period DD system yet discovered) is found. Two other excellent and two good DD candidates, and two white dwarf + red dwarf pairs were also found. If all the candidates should be confirmed, this would indicate a frequency of about 13 percent of interacting binaries in an unbiased sample of evolved stars, with a DD frequency of about 10 percent. These results suggest fairly large values for the common-envelope parameter alpha, implying that a source of energy other than orbital may be required to eject the envelope during common-envelope events. Finally, in combination with previous evidence our result implies that DDs with WD components of the DA variety are unlikely to be the precursors of Type I supernovae, but DDs with non-DA components remain very attractive candidates. Publication: The Astrophysical Journal Pub Date: December 1990 DOI: 10.1086/185877 Bibcode: 1990ApJ...365L..13B Keywords: Degenerate Matter; Double Stars; Supernovae; White Dwarf Stars; Red Dwarf Stars; Roche Limit; Stellar Envelopes; Stellar Mass Ejection; Astrophysics; STARS: BINARIES; STARS: STELLAR STATISTICS; STARS: SUPERNOVAE; STARS: WHITE DWARFS full text sources ADS | data products SIMBAD (27)