Bibcode
Santander-García, M.; Rodríguez-Gil, P.; Corradi, R. L. M.; Jones, D.; Miszalski, B.; Boffin, H. M. J.; Rubio-Díez, M. M.; Kotze, M. M.
Bibliographical reference
Nature, Volume 519, Issue 7541, pp. 63-65 (2015).
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3
2015
Journal
Citations
69
Refereed citations
54
Description
The planetary nebula stage is the ultimate fate of stars with masses one
to eight times that of the Sun (). The origin of their complex
morphologies is poorly understood, although several mechanisms involving
binary interaction have been proposed. In close binary systems, the
orbital separation is short enough for the primary star to overfill its
Roche lobe as the star expands during the asymptotic giant branch phase.
The excess gas eventually forms a common envelope surrounding both
stars. Drag forces then result in the envelope being ejected into a
bipolar planetary nebula whose equator is coincident with the orbital
plane of the system. Systems in which both stars have ejected their
envelopes and are evolving towards the white dwarf stage are said to be
double degenerate. Here we report that Henize 2-428 has a
double-degenerate core with a combined mass of ~1.76, which is above the
Chandrasekhar limit (the maximum mass of a stable white dwarf) of 1.4.
This, together with its short orbital period (4.2 hours), suggests that
the system should merge in 700 million years, triggering a type Ia
supernova event. This supports the hypothesis of the double-degenerate,
super-Chandrasekhar evolutionary pathway for the formation of type Ia
supernovae.
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