The mass of the white dwarf in GW Libra
Abstract
We report a mass and rotational broadening (vsini) for the pulsating white dwarf component of the WZ Sge type Dwarf Nova GW Lib based on high-resolution VLT spectroscopy that resolves the MgII 4481A absorption feature. Its gravitational redshift combined with white dwarf mass-radius models, provides us with a direct measurement of the white dwarf mass of M1 = 0.84 pm 0.02 Msun. The line is clearly resolved and if associated with rotational broadening gives vsini=87.0 pm 3.4 km/s, equivalent to a spin period of 97 pm 12s.
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