Why Distant Supernovae Explosions Outside Galaxies Excite Astronomers

Three supernovae explosions in distant space have got astronomers excited about the location of the stellar events.

The sightings were made by Hubble Space Telescope, confirming earlier sightings of the supernovae. Researchers who sighted the explosions are excited as they happened at a location far outside any galaxy. Supernovas are usually found inside galaxies. The stars which exploded were about 300 million light-years away from nearest galaxy. The stars exploded billion light-years away from Earth.

The sightings are rare and important as it reveals to researchers the forces at work in the inter-galactic space. Strong gravitational forces between galactic neighbors can wrench away 15 percent of stars from a galaxy and leave them isolated. Such stars are faint by themselves but can be seen when they explode as supernovae.

"We have provided the best evidence yet that intra-cluster stars truly do explode as Type Ia supernovae and confirmed that host-less supernovae can be used to trace the population of intra-cluster stars, which is important for extending this technique to more distant clusters," said Melissa Graham a post-doctoral fellow at UC Berkeley, who led the study.

The researchers also spotted a fourth exploding star in a red round region that could be a small galaxy or a globular cluster. If it is, this the first time a supernova has been spotted in dense small cluster.

"Since there are far fewer stars in globular clusters, only a small fraction of the supernovae are expected to occur in globular clusters. This might be the first confirmed case, and may indicate that the fraction of stars that explode as supernovae is higher in either low-mass galaxies or globular clusters," Graham said.