The double degenerate LP400-22 revisited

Abstract

We re-examine the properties of the high-velocity and extremely low mass white dwarf LP 400-22 and its close companion. Based on an extended observation timeline we determined a binary period of P= 1.01016 d, somewhat longer than the previously published period, and a mass function f(M_2)= 0.180 M_solar implying a mass for the companion M_2 > 0.41 M_solar. We also re-appraised the mass and cooling age of the white dwarf using low-metallicity (Z=0.001) evolutionary models appropriate for an old halo member, M_1 = 0.19 M_solar and t_cool~1.8 Gyr, and we infer a mass of 0.85 - 1.0 M_solar for the progenitor of the white dwarf. We discuss the likely origin of this system.

Accepted for publication in A&A

References in corpus (6)

• The masses of PSR J1911-5958A and its white dwarf companion
• The Discovery of a Companion to the Lowest Mass White Dwarf
• Populating the Galaxy with pulsars -- II. Galactic dynamics
• LP 400-22, A very low-mass and high-velocity white dwarf
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Cited by in corpus (11)

• The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
• The ELM Survey. IV. 24 White Dwarf Merger Systems
• The ELM Survey. V. Merging Massive White Dwarf Binaries
• The Discovery of Binary White Dwarfs that will Merge within 500 Myr
• The ELM Survey. VI. Eleven New Double Degenerates
• Discovery of a Bright, Extremely Low-Mass White Dwarf in a Close Double Degenerate System
• Orbital properties of an unusually low-mass sdB star in a close binary system with a white dwarf
• Accurate Masses for the Primary and Secondary in the Eclipsing White Dwarf Binary NLTT 11748
• The double degenerate system NLTT 11748
• The Runaway Binary LP 400-22 is Leaving the Galaxy
• Dynamically Forming Extremely Low-Mass White Dwarf Binaries in Wide Orbits