Exploding star at edge of galaxy

Astronomers believe they have observed the most distant explosion – and possibly the most distant object – ever seen in the Universe: an exploding star with a redshift of 9.4.

The exploding star – a gamma-ray burst (GRB) – was first detected by NASA’s Swift satellite in April 2009, but over the past two years, a team of international researchers have been examining their data to see if the burst really was a record breaker.

The research involved major contributions from the Universities of Leicester and Warwick. Dr Andrew Levan from Warwick was one of the first to observe the explosion.

“The race to find distant objects stems from the desire to find and study the first stars and galaxies that formed in the Universe, in the first few hundred million years after the Big Bang.”

When a star explodes, it can be as bright as several thousand galaxies – more than a million million times brighter than the Sun – for a few minutes. Their fading afterglow remains observable with very large telescopes – like Swift, the Hubble Space Telescope and the Gemini North Observatory used in this research – for days, even weeks.

Sophisticated analysis of this afterglow light led researchers to conclude that the GRB has a redshift – a measure of distance used by astronomers – of approximately 9.4. This puts the star at an estimated distance of 13.14 billion light years – approximately 96% of the way to the edge of our observable Universe.

“This GRB shows us that there is a lot of action going on in the Universe which we can’t currently see,” said Professor Nial Tanvir, leader of the Hubble Space Telescope programme, which was also involved in the research.

“Our observations show us that even the Hubble Space Telescope is only seeing the tip of the iceberg in the distant Universe.”