Discovery of a hot ultramassive rapidly rotating DBA white dwarf
Postnov, K. A.; Blinnikov, S. I.; Dodin, A. V.; Potanin, S. A.; Zheltoukhov, S. G.; Belinski, A. A.; Pshirkov, M. S.; Fedoteva, A. A.; Voziakova, O. V.
Russia, Ukraine
Abstract
We report the discovery of a nearby massive white dwarf with He-H atmosphere. The white dwarf is located at a distance of 74.5 ± 0.9-=pc. Its radius, mass, effective temperature, H/He ratio, and age are R = 2500 ± 100-=km, M = 1.33 ± 0.01-= $\rm M_{\odot }$ , Teff = 31-=200 ± 1200-=K, H/He ∼ 0.1, and 330 ± 40-=Myr, respectively. The observed spectrum is redshifted by Vr = +240 ± 15-=km-=s-1, which is mostly attributed to the gravitational redshift. The white dwarf shows a regular stable photometric variability with amplitude Δg ≈ 0.06m and period P = 353.456 s suggesting rapid rotation. This massive, hot, and rapidly rotating white dwarf is likely to originate from the merging of close binary white dwarf system that avoided explosion in a thermonuclear Type Ia supernova.