The double degenerate LP 400-22 revisited*
Astronomický ústav AV ČR, Fričova 298, 251 65 Ondřejov, Czech Republic e-mail: vennes, email@example.com
2 Department of Physics & Astronomy, Francis Marion University, Box 100547, Florence, SC 29501, USA e-mail: firstname.lastname@example.org
3 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA e-mail: email@example.com
Accepted: 17 September 2009
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 d, somewhat longer than the previously published period, and a mass function = 0.180 , implying a mass for the companion M2 > 0.41 . We also re-appraised the mass and cooling age of the white dwarf using low-metallicity () evolutionary models appropriate for an old halo member, M1 = 0.19 , and ≈1.8 Gyr, and we infer a mass of 0.85–1.0 for the progenitor of the white dwarf. We discuss the likely origin of this system.
Key words: stars: binaries: close / stars: individual: LP 400-22 / white dwarfs
© ESO, 2009