Feb. 26,
2006
Courtesy Penn State University
and World Science staff
Astronomers say they have detected a new type of cosmic explosion that has sent scientists around the world scrambling to telescopes to document the startling event.
Radiation from the blast, detected on Feb. 18 and lasting about half an hour, appears to be a precursor to a supernova, the death blast of a massive star, they said.
Scores of satellites and ground-based telescopes also are now trained on the sight, researchers said. They added that amateur astronomers in the northern hemisphere with a good telescope in dark skies also can view the source.
The explosion has the trappings of a gamma-ray burst, the most distant and powerful type of explosion known, researchers said.
“The observations indicate that this is an incredibly rare glimpse of an initial gamma-ray burst at the beginning of a supernova,” said Peter Brown, a graduate student of Penn State University in University Park, Penn., and a member of the Swift science team.
This event, however, was about 25 times closer and 100 times longer than the typical gamma-ray burst, the researchers added.
It was “totally new and unexpected,” said Neil Gehrels, principal investigator for NASA’s Swift satellite, which was used to make the finding. “This is the type of unscripted event in our nearby universe that we hoped Swift could catch.”
The explosion, called GRB 060218 after the date it was discovered, originated in a star-forming galaxy about 440 million light-years away toward the constellation Aries. This is the second closest gamma-ray burst ever detected, if indeed it is a true burst, researchers said.
“This is extremely exciting, not only for what it can potentially tell us about the relationship between gamma-ray bursts and ‘ordinary’ supernova explosions, but also because the detection of the gamma-ray flash has alerted us to the potential presence of a nearby supernova, which we can now study in detail from the very beginning,” said Keith Mason, chief executive of the U.K.’s Particle Physics and Astronomy Research Council, one of the researchers.
“Usually these events are not detected until after the exploding star has brightened substantially.”
In a separate event that further heightened hopes for
capturing supernovae early, a European team led by Italy’s National
Institute for Astrophysics reported Feb. 24 that it has found hints of a
budding supernova.
The team studied the spectrum of light emitted by the event, using
the European Southern Observatory’s Very Large Telescope in Chile.
“We expected to see the typical featureless spectrum of a
gamma-ray burst afterglow, but instead we found a mixture between this and
the more complex spectrum of a supernova similar to those generally
observed weeks after the gamma-ray burst,” said Nicola Masetti of the
institute. “A supernova must be in the works.”
