science & techESA/Hubble2008 · Pegasus constellation
A galaxy's supernova was probably only a partial explosion, a failed version of a stellar death
SN 2008ha was a supernova in the galaxy UGC 12682, about 70 million light-years away, and it was unusually weak. It was one of the faintest supernovae ever observed, and it expanded very slowly, which means it released far less energy than a typical explosion. Astronomers now classify it as a subclass of Type Ia supernova, the explosion of a white dwarf that pulls matter from a companion star. The leading explanation is that the blast was only partly successful, and the explosion did not destroy the whole star.
A Type Ia supernova begins when a white dwarf, the dense remnant of a Sun-like star, gathers gas from a companion star until it reaches a critical mass. It then undergoes a runaway nuclear reaction that blows it apart. In a weak event, the reaction fizzles before it consumes the whole star, so less energy is released and the debris expands more slowly.
Type Ia supernovae are used as standard candles to measure distances across the universe, so understanding the odd members of the family matters for accuracy. A weak, partly failed explosion shows that the family is more varied than once assumed. The discovery was also made by a 14-year-old amateur astronomer, Caroline Moore, who spotted it in 2008.
background
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.
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.
From Wikipedia: SN 2008ha (CC BY-SA 4.0) ↗
