An unusual white dwarf star may be a surviving remnant of a subluminous Type Ia supernova

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Science  18 Aug 2017:
Vol. 357, Issue 6352, pp. 680-683
DOI: 10.1126/science.aam8378

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Unusual star may be supernova debris

Type Ia supernovae occur when a white dwarf star is completely destroyed in a thermonuclear explosion. Recently, another class of supernova has been found, dubbed type Iax; these look like type Ia but are much fainter and may be the result of only partial destruction of a white dwarf. In support of this notion, Vennes et al. found a white dwarf star in our Galaxy that is low-mass, is moving quickly, and has an unusual composition. These properties suggest that it could be the predicted leftover remains from a type Iax supernova.

Science, this issue p. 680


Subluminous Type Ia supernovae, such as the Type Iax–class prototype SN 2002cx, are described by a variety of models such as the failed detonation and partial deflagration of an accreting carbon-oxygen white dwarf star or the explosion of an accreting, hybrid carbon-oxygen-neon core. These models predict that bound remnants survive such events with, according to some simulations, a high kick velocity. We report the discovery of a high proper motion, low-mass white dwarf (LP 40-365) that travels at a velocity greater than the Galactic escape velocity and whose peculiar atmosphere is dominated by intermediate-mass elements. Strong evidence indicates that this partially burnt remnant was ejected following a subluminous Type Ia supernova event. This supports the viability of single-degenerate supernova progenitors.

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