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The discovery of a short-period double-degenerate binary star

1995/04/25 by T. R. Marsh · 4 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Binary number #Binary star #Degenerate energy levels #Mass ratio #Orbital period #Physics #Radial velocity #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph

paper · pdf · doi:10.1093/mnras/275.1.l1

MNRAS pink pages in press. 5 pages including figures, uuencoded compressed PostScript

arxiv created 1995/04/25 · openalex publication_date 1995/07/01 · arxiv updated 2016/06/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We have found that the white dwarf PG 1101 + 364 is a double-lined white dwarf/white dwarf binary with an orbital period of 3.47 h. PG 1101 + 364 is the shortest period detached double-degenerate yet found, and gravitational radiation will cause it to merge in 2.5 × 109 yr. PG 1101 + 364 has a mass ratio of 0.87 ± 0.03. From the relative strengths of the narrow core of Hα, the lighter and therefore larger star appears to contribute more of the light by an amount that indicates almost equal temperatures for the two stars. We chose to observe PG 1101 + 364 on the basis of its low spectroscopic mass (0.31 M⊙), and the discovery of its binary nature confirms the belief that binary evolution is required to produce such low mass white dwarfs. The radial velocity semi-amplitudes (69.7 ± 1.7 and 80.3 ± 1.6 km s–1) and the spectroscopic mass show that we see the orbit of PG 1101 + 364 at a low inclination of ≈ 25°.

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