 | |
| Event type | Supernova  |
|---|---|
| Ia 2002cx-like[1] | |
| Date | November 7, 2008 |
| Constellation | Pegasus |
| Right ascension | 23 h 34 m 52 s |
| Declination | +18°13'35" |
| Epoch | J2000.0 |
| Galactic coordinates | 098.5631 −40.9944 |
| Distance | 21.3 Mpc (69 Mly) |
| Redshift | 0.0069, 0.0046, 0.0047 |
| Host | UGC 12682 |
| Other designations | SN 2008ha |
SN 2008ha was a type Ia supernova which was first observed around November 7, 2008 in the galaxy UGC 12682, which lies in the constellation Pegasus at a distance of about 21.3 megaparsecs (69 Mly) from Earth.[1]
SN 2008ha was unusual in several ways: with an absolute V band magnitude of −14.2 it is one of the faintest supernovae ever observed; its host galaxy type very rarely produces supernovae. Another unusual feature of SN 2008ha was its low expansion velocity of only ~2000 km/s at maximum brightness, which indicates a very small kinetic energy released in the explosion. For comparison, SN 2002cx expanded at a velocity of ~5000 km/s whereas typical SN Ia expand at around ~10,000 km/s. The low expansion velocity of SN2008ha resulted in relatively small Doppler broadening of spectral emission lines and this led to higher quality data.
The supernova was studied with ultraviolet, optical, and near-infrared photometry as well as optical spectra, using the Magellan telescopes in Chile, the MMT telescope in Arizona, the Gemini and Keck telescopes in Hawaii, and NASA's Swift satellite. Spectroscopically, SN 2008ha was identified as a SN 2002cx-type, a peculiar sub-class of SN Ia. SN 2008ha had a brightness period of only 10 days, which is significantly shorter than that of other SN 2002cx-like objects (~15 days) or normal Ia supernovas (~20 days). From the peak luminosity and the brightness time it was estimated that SN 2008ha generated (3.0 ± 0.9) × 10−3 M⊙ of 56Ni, had a kinetic energy of 2 × 1048 ergs, and ejected 0.15 M⊙ of material.[1][2]
- ^ a b c Foley, Ryan J.; Chornock, Ryan; Filippenko, Alexei V.; Ganeshalingam, Mohan; Kirshner, Robert P.; Li, Weidong; Cenko, S. Bradley; Challis, Peter J.; et al. (2009). "SN 2008ha: an extremely low luminosity and exceptionally low energy supernova". The Astronomical Journal. 138 (2): 376. arXiv:0902.2794. Bibcode:2009AJ....138..376F. doi:10.1088/0004-6256/138/2/376. S2CID 13855329.
- ^ Valenti, S; Pastorello, A; Cappellaro, E; Benetti, S; Mazzali, PA; Manteca, J; Taubenberger, S; Elias-Rosa, N; et al. (Jun 2009). "A low-energy core-collapse supernova without a hydrogen envelope". Nature. 459 (7247): 674–7. arXiv:0901.2074. Bibcode:2009Natur.459..674V. doi:10.1038/nature08023. PMID 19494909. S2CID 4418638.