1. A faint type of supernova from a white dwarf with a helium-rich companion.
- Author
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Perets HB, Gal-Yam A, Mazzali PA, Arnett D, Kagan D, Filippenko AV, Li W, Arcavi I, Cenko SB, Fox DB, Leonard DC, Moon DS, Sand DJ, Soderberg AM, Anderson JP, James PA, Foley RJ, Ganeshalingam M, Ofek EO, Bildsten L, Nelemans G, Shen KJ, Weinberg NN, Metzger BD, Piro AL, Quataert E, Kiewe M, and Poznanski D
- Abstract
Supernovae are thought to arise from two different physical processes. The cores of massive, short-lived stars undergo gravitational core collapse and typically eject a few solar masses during their explosion. These are thought to appear as type Ib/c and type II supernovae, and are associated with young stellar populations. In contrast, the thermonuclear detonation of a carbon-oxygen white dwarf, whose mass approaches the Chandrasekhar limit, is thought to produce type Ia supernovae. Such supernovae are observed in both young and old stellar environments. Here we report a faint type Ib supernova, SN 2005E, in the halo of the nearby isolated galaxy, NGC 1032. The 'old' environment near the supernova location, and the very low derived ejected mass ( approximately 0.3 solar masses), argue strongly against a core-collapse origin. Spectroscopic observations and analysis reveal high ejecta velocities, dominated by helium-burning products, probably excluding this as a subluminous or a regular type Ia supernova. We conclude that it arises from a low-mass, old progenitor, likely to have been a helium-accreting white dwarf in a binary. The ejecta contain more calcium than observed in other types of supernovae and probably large amounts of radioactive (44)Ti.
- Published
- 2010
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