Friday, December 21, 2007

A Shot in the Dark

Earlier this week astronomer's announced that they had found yet another mysterious gamma-ray burst. NASA's Swift satellite detected GRB 070125 last January in the constellation of Gemini and sent its alert to ground-based astronomers.

Palomar's 60-inch telescope was one of the first to respond. The 60-inch, and indeed the entire observatory, is linked into the
High Performance Wireless Research and Education Network (HPWREN). HPWREN enabled the message from Swift to be received, allowing the automated 60-inch telescope to quickly measure the fast-fading visible-light afterglow of the GRB. Data was then sent away from Palomar. Measurements prompted observations with the giant 8-meter Gemini North telescope and the 10-meter Keck I telescope, both located in Hawaii. Astronomers were able to determine the distance to the GRB - 9.4 billion light-years distant.

Astronomers are interested in things like the peak brightness of the burst, how fast it fades, its distance and what type of galaxy it is located in. Measurements indicated that this burst was likely produced by the collapse and explosion of a massive star. These stars "live fast and die young" and are expected to be found in a galaxy where new stars are being produced, yet deep images from Keck failed to find any signs of a galaxy. This means there shouldn't have been that type of star where the burst was seen.

So where did this burst come from? Maybe a faint tidal tail, produced as galaxies collide, is lurking too faint for even Keck to see. Maybe our understanding of this type of GRB is flawed. Deep searches with the Hubble Space Telescope hope to answer the question soon. Stay tuned.

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