SDSS¿J124043.01+671034.68: the partially burned remnant of a low-mass white dwarf that underwent thermonuclear ignition?
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hdl:2117/339664
Tipus de documentArticle
Data publicació2020-08-21
EditorOxford University Press
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Abstract
The white dwarf SDSS¿J124043.01+671034.68 (SDSS¿J1240+6710) was previously found to have an oxygen-dominated atmosphere with significant traces of neon, magnesium, and silicon. A possible origin via a violent late thermal pulse or binary interactions has been suggested to explain this very unusual photospheric composition. We report the additional detection of carbon, sodium, and aluminium in far-ultraviolet and optical follow-up spectroscopy. No iron-group elements are detected, with tight upper limits on titanium, iron, cobalt, and nickel, suggesting that the star underwent partial oxygen burning, but failed to ignite silicon burning. Modelling the spectral energy distribution and adopting the distance based on the Gaia parallax, we infer a low white dwarf mass, $M_\mathrm{wd}=0.41\pm 0.05\, \mathrm{M}_\odot$. The large space velocity of SDSS¿J1240+6710, computed from the Gaia proper motion and its radial velocity, is compatible with a Galactic rest-frame velocity of ¿ 250¿km¿s-1 in the opposite direction with respect to the Galactic rotation, strongly supporting a binary origin of this star. We discuss the properties of SDSS¿J1240+6710 in the context of the recently identified survivors of thermonuclear supernovae, the D6 and LP¿40-365 stars, and conclude that it is unlikely related to either of those two groups. We tentatively suggest that SDSS¿J1240+6710 is the partially burned remnant of a low-mass white dwarf that underwent a thermonuclear event.
CitacióGänsicke, B.T. [et al.]. SDSS¿J124043.01+671034.68: the partially burned remnant of a low-mass white dwarf that underwent thermonuclear ignition? "Monthly notices of the Royal Astronomical Society", 21 Agost 2020, vol. 496, núm. 4, p. 4079-4086.
ISSN0035-8711
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