Mon. Not. R. Astron. Soc., 483, 901-907 (2019/February-2)
Discovery of the first resolved triple white dwarf.
PERPINYA-VALLES M., REBASSA-MANSERGAS A., GANSICKE B.T., TOONEN S., HERMES J.J., GENTILE FUSILLO N.P. and TREMBLAY P.-E.
Abstract (from CDS):
We report the discovery of J1953-1019, the first resolved triple white dwarf system. The triplet consists of an inner white dwarf binary and a wider companion. Using Gaia DR2 photometry and astrometry combined with our follow-up spectroscopy, we derive effective temperatures, surface gravities, masses, and cooling ages of the three components. All three white dwarfs have pure-hydrogen (DA) atmospheres, masses of 0.60-0.63 M☉, and cooling ages of 40-290 Myr. We adopt eight initial-to-final mass relations to estimate the main-sequence progenitor masses (which we find to be similar for the three components, 1.6-2.6 M☉) and lifetimes. The differences between the derived cooling times and main sequence lifetimes agree for most of the adopted initial-to-final mass relations, hence the three white dwarfs in J1953-1019 are consistent with coeval evolution. Furthermore, we calculate the projected orbital separations of the inner white dwarf binary (303.25 ± 0.01 au) and of the centre of mass of the inner binary and the outer companion (6398.97±0.09 au). From these values, and taking into account a wide range of possible configurations for the triplet to be currently dynamically stable, we analyse the future evolution of the system. We find that a collision between the two inner white dwarfs due to Lidov-Kozai oscillations is unlikely, though if it occurs it could result in a sub-Chandrasekhar Type Ia supernova explosion.
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
binaries: close - stars: individual: J1953-1019 - white dwarfs
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