By: Eugene Magnier

Eugene Magnier — Wed, 11 Mar 2015 00:49:18 +0000

Thanks for the comment. You are right about point (1): we did not really explain the double-detonation in the caption. In such a supernova, an Oxygen/Carbon white dwarf accumulates Hydrogen and Helium from a donor star (in this case, the star destined to become US708). When enough H/He accumulate on the surface of the white dwarf, they can spontaneously ignite in a fusion reaction. The heat and pressure from that reaction can then trigger a fusion reaction in the O/C white dwarf, resulting in the full-scale supernova (Type Ia).

As for your points 2 & 3, it is typical in astronomy to refer to the “Type Ia” or white-dwarf supernova, like I described above, as “thermonuclear” because the reaction is driven and sustained by the high temperatures (of the H/He reaction and the radioactive decay of the nickel by products). The other kind of supernova, in which massive star explodes, is called a core-collapse supernova, not a thermonuclear supernova. In the core collapse case, the supernova explosion is not driven by high temperatures, but instead by gravity. So, in this case, the supernova that disrupted the system and resulted in the high velocity of US708 was a thermonuclear, not a core-collapse supernova.

By: Mr. Raymond Kenneth Petry

Mr. Raymond Kenneth Petry — Tue, 10 Mar 2015 03:14:11 +0000

That was ‘one’ confused report—
1. The IFA captioned it a “double detonation” (but no explanation why);
2. All supernovae we know-about are ‘thermonuclear’ (beyond neutrinos);
3. Categorically ‘thermonuclear’ implicates the impulse given its core.
(And cores are considered stars too, e.g. ‘neutron stars’.)
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Comments on: Fastest star in Milky Way propelled by a thermonuclear supernova

By: Eugene Magnier

By: Mr. Raymond Kenneth Petry