An ancient double degenerate merger in the Milky Way halo

Abstract

We present an analysis and re-appraisal of the massive, carbon-enriched (DQ) white dwarf (WD) LP 93-21. Its high mass (~1 M_sun) and membership to the class of warm DQ WDs, combined with its peculiar halo kinematics suggest that this object is the product of an ancient stellar merger event, most likely that of two WDs. Furthermore, the kinematics places this object on a highly retrograde orbit driven by the accretion of a dwarf galaxy onto the Milky Way that occurred at a red shift greater than 1.5. As the product of a stellar merger LP 93-21 is probably representative of the whole class of warm/hot DQ WDs.

Accepted for publication in MNRAS Letters

References in corpus (6)

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• Hot DQ White Dwarfs: Something Different
• Origin of the excess of high-energy retrograde stars in the Galactic halo
• An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova
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• An in-depth reanalysis of the alleged type Ia supernova progenitor Henize 2-428
• The non-explosive stellar merging origin of the ultra-massive carbon-rich white dwarfs
• The nearby magnetic cool DZ white dwarf PM J08186-3110
• Astrophysics with the Laser Interferometer Space Antenna
• A Catalog of 531 White Dwarf Candidates in the Local Galactic Halo from Gaia Data Release 2
• Two hot pre-white dwarfs inside the red-giant-branch planetary nebula Pa 13 -- Double core evolution or common envelope-induced rejuvenation?