| Issue |
A&A
Volume 507, Number 3, December I 2009
|
|
|---|---|---|
| Page(s) | 1613 - 1616 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361/200912955 | |
| Published online | 08 October 2009 | |
The double degenerate LP 400-22 revisited*
1
Astronomický ústav AV ČR, Fričova 298, 251 65 Ondřejov, Czech Republic e-mail: vennes, kawka@sunstel.asu.cas.cz
2
Department of Physics & Astronomy, Francis Marion University, Box 100547, Florence, SC 29501, USA e-mail: tvaccaro@fmarion.edu
3
Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA e-mail: nms@astro.washington.edu
Received:
22
July
2009
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
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