SN 2008ax
2008 supernova event in constellation Canes Venatici
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SN 2008ax was a helium-rich type Ib core-collapse supernova in the interacting galaxy NGC 4490.[3] It was independently discovered on 3 March 2008 by LOSS[5] and 4 March by Koichi Itagaki.[6] The site had been monitored six hours before discovery, thus constraining the time of the explosion breakout.[3] It was the third-brightest supernova of 2008.[7] The brightness in the B-band peaked about 20 days after the explosion.[3] X-ray emissions were detected from the event, which are most likely the result of shock heating from the supernova ejecta and circumstellar material.[8]
Position of SN 2008ax in NGC 4490; image courtesy of Hunter Wilson | |
| Event type | Supernova |
|---|---|
| Type Ib[1] | |
| Date | 3 March 2008 |
| Constellation | Canes Venatici |
| Right ascension | 12h 30m 40.80s[2] |
| Declination | +41° 38′ 16.1″[2] |
| Epoch | J2000.0 |
| Galactic coordinates | b = 137.95°, l = +74.88°[2] |
| Distance | 31 Mly (9.6 Mpc)[3] |
| Source | NGC 4490 |
| Peak apparent magnitude | +13.0[4] |
Images of the source location made using the Hubble Space Telescope in 2011 and 2013 were used to identify the progenitor. If it was a single star, the images are compatible with a supergiant star with a class of B to mid-A type. However, this is not favored by models which indicate the progenitor had a relatively low mass of 4–5 M☉ and extended hydrogen-rich atmosphere with a radius of 30–40 R☉. An alternative, more plausible model suggests the progenitor was part of an interacting binary system where much of the atmosphere was lost through mass transfer to the companion.[1]