Last month, the Swift satellite based in State College detected a cosmic explosion that may have indicated a supernova.
The explosion, called GRB 060218, lasted about 30 minutes and seems to be a precursor to a supernova, which is the death of a star larger than the sun. The origin of the cosmic explosion was in a galaxy about 440 million light years away.
Derek Fox, assistant professor of astronomy and astrophysics and leader of the monitoring efforts of GRB 060218 on the Hobby-Eberly Telescope, said the explosion emanated from the northwest part of the sky, near the constellation Aries. Gamma-ray bursts are the most powerful and distant type of explosions known, and this cosmic explosion has evidence of being a gamma-ray burst. However, this explosion was about 25 times closer and 100 times longer than the average gamma-ray burst. Swift's Mission Operations Director John Nousek said the burst was dimmer than other bursts.
"It looks like it gave off less energy. It is halfway between a supernova and a bright X-ray transient," said Nousek, professor of astronomy and astrophysics.
Most bursts last a couple of milliseconds to tens of seconds; however, this explosion lasted for almost 2,000 seconds. Fox said the probability of an explosion like this happening is about 1 percent.
"I think what we're seeing is the star itself exploding," said Fox.
The extended time of the explosion and the proximity still make this cosmic explosion quite unusual.
"I would just say the reason we're so excited is because of the burst that happened in 1998," said Fox. The 1998 burst was the closest gamma-ray burst ever. If GRB 060218 is truly a burst, it would be the second closest gamma-ray burst detected.
The 1998 burst was not monitored by Swift satellite because Swift wasn't launched until November 2004. Originally, it was not certain what exactly this new explosion was.
"The reason there was uncertainty was because it was closer than most gamma-ray bursts," said Nousek. "I would say this explosion is a rare gamma-ray burst, not something fundamentally new."
Fox said that data comes down from the Swift satellite every day. Nousek said Swift carries three different instruments, including the X-Ray Telescope and the UV/Optical Telescope that enable the most detailed observations of gamma-ray bursts to date. The X-Ray Telescope is designed to measure the position, spectrum and brightness of gamma-ray bursts, Nousek said. The UV/Optical Telescope, co-aligned with the other two instruments, provides simultaneous ultraviolet and optical coverage, Nousek said.
The third instrument on the Swift satellite is the Burst Alert Telescope, which Nousek said calculates an initial position and sends the position to the spacecraft if the burst merits a spacecraft slew.
