Exeter team helps set astronomy record

The detection of the gamma-ray burst, named GRB 090423, is reported in two papers now published in leading academic journal Nature. The explosion is thought to accompany the catastrophic death of a very massive star as it ended its life, and is triggered by the centre of the star collapsing to form a black hole.

An automated software system called eSTAR is run by Exeter astronomers Dr Alasdair Allan and Professor Tim Naylor and links telescopes from around the world. eSTAR first picked up the gamma-ray burst alert from the Swift satellite, and calculated that the STFC’s United Kingdom Infrared Telescope UKIRT) on Mauna Kea, Hawaii could observe exactly the right spot in the sky. It then sent the telescope detailed instructions as to what was required. 21 minutes after the alert, a UKIRT observation began, which successful detected the gamma-ray burst.

"The observations with UKIRT via eSTAR and the GCN were critical," said Dr Alasdair Allan of the University of Exeter's School of Engineering, Physical Sciences and Mathematics. "It was undetectable in the optical for those telescopes that attempted to observe it, as the high redshift made it very faint in the optical bands. The UKIRT detection triggered the use of some large, 8 and 10m optical facilities. Only with these larger telescopes was the event detectable in the optical bands."

Gamma-ray bursts are the Universe's most luminous explosions. Most occur when massive stars run out of nuclear fuel. As their cores collapse into a black hole or neutron star, gas jets - driven by processes not fully understood - punch through the star and blast into space. There, they strike gas previously shed by the star and heat it, which generates short-lived afterglows in other wavelengths.

The University of Exeter has one of the UK’s largest astrophysics groups working in the fields of star formation and exoplanet research. The group focuses on one of the most fundamental problems in modern astronomy – when do stars and planets form and how does it happen? They conduct observations with the world’s leading telescopes and carry out numerical simulations to study young stars, their planet-forming discs, and exoplanets. This research helps to put our Sun and the solar system into context and understand the variety of stars and planetary systems that exist in our Galaxy. Over the next three years, the University is investing £80 million in five areas of interdisciplinary scientific research, one of which is Extrasolar Planets.