NASA’s Hubble Space Telescope has imaged an incredible stellar explosion, blazing at an immense distance of over 7 billion light years, about halfway to the edge of the observable Universe. This is a type of fantastic cosmic explosions known as gamma-ray bursts (GRBs), extremely luminous flashes of gamma rays and other radiations, often lasting a few minutes or less. They are believed to be the explosions of hefty stars that are up to 50 times more massive than the Sun.

Hubble detected the visible light radiated through the GRB event. It appeared in our skies as a star-like object, barely visible to the unaided eye, but its intrinsic luminosity was as brilliant as 10 million galaxies!! Actually, it holds the record of the intrinsically brightest naked-eye object ever observed.

The GRB, designated GRB 080319B, occurred on 19 March 2008, and lasted nearly one minute. Hubble’s Wide Field and Planetary Camera 2 (WFPC2) images, taken on 7 April 2008, show the fading optical counterpart of the titanic blast. It was not possible to image the mother galaxy of the GRB, as it was still overwhelmed by the glare of the GRB.

The object erupted in a brilliant flash of gamma rays and other electromagnetic emissions, and was also detected by NASA's gamma ray burst satellite, Swift. Immediately after the explosion, the gamma ray burst glowed as a faint star in the spring constellation Bootes; its light has been fading since then.

This is particularly surprising because bright bursts have been known to decline in brightness more rapidly, in conformity with the theory that powerful GRBs emit their energy in a more tightly confined beam. The slow fading demands crucial new HST observations of GRB 080319B, due in May 2008.

Such explosions are also known as "hypernovae," as they are more powerful than ordinary supernova explosions and are far more luminous. Their energy rather seems to be concentrated into a blowtorch-like beam that, in this case, was aimed directly at Earth. The Hubble image also shows field galaxies around the object, which are probably unrelated to the burst itself.

Further Reading

Hubble Site
http://hubblesite.org/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist