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arXiv · 0909.3261

The double degenerate LP400-22 revisited

S. Vennes·A. Kawka·T. R. Vaccaro·N. M. Silvestri
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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.

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S. Vennes, A. Kawka, T. R. Vaccaro, N. M. Silvestri. 2009-10-05. The double degenerate LP400-22 revisited. https://doi.org/10.1051/0004-6361%2F200912955

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