Is There Evidence of a Type Ia Supernova Formed via the Single Degenerate Mode?

[Chronos]

This paper - http://arxiv.org/abs/1505.05158, Strong Ultraviolet Pulse From a Newborn Type Ia Supernova- discusses the first well established evidence of a type Ia supernova formed via the single degenerate mode. The double degenerate mode has gained considerable support over the past decade or so given the lack of evidence of any surviving companion star after an SNIa event. The single degenerate mode suffers the undeniable [and fortuitous] handicap that SNIa are generally too distant to permit detection of any surviving companion stars. It appears this particular SNIa belongs to a class of subluminous SNIa that are generally not relied upon as standard candles, although potential cosmological implications are not really addressed.

 

[|Glitch|]

This paper - http://arxiv.org/abs/1505.05158, Strong Ultraviolet Pulse From a Newborn Type Ia Supernova- discusses the first well established evidence of a type Ia supernova formed via the single degenerate mode. The double degenerate mode has gained considerable support over the past decade or so given the lack of evidence of any surviving companion star after an SNIa event. The single degenerate mode suffers the undeniable [and fortuitous] handicap that SNIa are generally too distant to permit detection of any surviving companion stars. It appears this particular SNIa belongs to a class of subluminous SNIa that are generally not relied upon as standard candles, although potential cosmological implications are not really addressed.

I wish the paper had included information concerning the velocity of the ejecta. Subluminous, or sub-Chandrasekhar, type Ia SNe are a relatively newly discovered phenomena. A new classification of SNe was proposed two years ago in order to distinguish them from the stereotypical Chandrasekhar type Ia SNe. The proposed new type Iax SNe have characteristics that allow us to easily distinguish between the two. For example, the ejecta velocity of all type Iax SNe is less than 8,000 km/s, the absolute visual magnitude varies between -14.2 and -18.9, and they have the same light-curve shape as SN 2002cx (which the paper you posted also references). All type Ia SNe have an ejecta velocity greater than 10,000 km/s and less than ~30,000 km/s, and have an absolute visual magnitude of -19.3.

According to the paper you posted, the iPTF14atg SN had an absolute magnitude of -17.9 and a similar light-curve shape as SN 2002cx, but it does not include information concerning the ejecta velocity. It is estimated that approximately 31% of all type Ia SNe are actually sub-Chandrasekhar type Iax SNe.

Type Iax Supernovae: A New Class of Stellar Explosion - The Astrophysical Journal, Volume 767, Number 1, Published March 25, 2013 (free issue)