. 24/7 Space News .
December 3 Gamma-Ray Burst Was A New Type Of Cosmic Explosion

Astronomers have now seen "haloes" around an extremely powerful, distant "headlight", a gamma-ray burst which occurred for about 30 seconds on December 3, 2003. The GRB was detected by the INTEGRAL observatory and soon afterwards, an X-ray "afterglow" from the GRB was observed by XMM-Newton observatory. As the afterglow was observed through the disk of our Galaxy, sheets of dust in the Galaxy scattered the X-rays and produced the halo. Four images of the "GRB halo", obtained 25, 35, 45, and 55 thousand seconds after the GRB, are shown above. The X-ray afterglow from the GRB is at the center of each halo. The haloes seem to be expanding, but this is an optical illusion; it simply takes a bit longer for the X-rays to be scattered by the more distant dust. Credit: ESA, S. Vaughan (University of Leicester) Online reference
Pasadena CA (SPX) Aug 09, 2004
Astronomers have identified a new class of cosmic explosions that are more powerful than supernovae but considerably weaker than most gamma-ray bursts. The discovery strongly suggests a continuum between the two previously-known classes of explosions.

In this week's issue of Nature, astronomers from the Space Research Institute of the Russian Academy of Sciences and the California Institute of Technology announce in two related papers the discovery of the explosion, which was first detected on December 3, 2003, by the European-Russian Integral satellite and then observed in detail at ground-based radio and optical observatories.

The burst, known by its birthdate, GRB031203, appeared in the constellation Puppis and is about 1.6 billion light-years away.

Although the burst was the closest gamma-ray burst to Earth ever studied (all the others have been several billion light-years away), researchers noticed that the explosion was extremely faint - releasing only about one-thousandth of the gamma rays of a typical gamma-ray burst.

However, the burst was also much brighter than supernovae explosions, which led to the conclusion that a new type of explosion had been found.

Both supernovae and the rare but brilliant gamma-ray bursts are cosmic explosions marking the deaths of massive stars. Astronomers have long wondered what causes the seemingly dramatic differences between these events.

The question of how stars die is currently a major focus of stellar research, and is particularly directed toward the energetic explosions that destroy a star in one cataclysmic event.

Stars are powered by the fusion ("burning'') of hydrogen in their interiors. Upon exhaustion of fuel in the interior, the core of massive stars collapse to compact objects - typically a neutron star and occasionally a black hole.

The energy released as a result of the collapse explodes the outer layers, the visible manifestation of which is a supernova. In this process, new elements are added to the inventory of matter in the universe.

However, this nuclear energy may be insufficient to power the supernova explosions. One theory is that additional energy is generated from the matter falling onto the newly produced black hole. Many astronomers believe that this is what powers the luminous gamma-ray bursts.

But the connection between such extreme events and the more common supernovae is not yet clear, and if they are indeed closely related, then there should be a continuum of cosmic explosions, ranging in energy from that of "ordinary" supernovae to that of gamma-ray bursts.

In 1998, astronomers discovered an extremely faint gamma-ray burst, GRB 980425, coincident with a nearby luminous supernova. The supernova, SN 1998bw, also showed evidence for an underlying engine, albeit a very weak one.

The question that arose was whether the event, GRB 980425/SN 1998bw, was a "freak" explosion or whether it was indicative of a larger population of low-powered cosmic explosions with characteristics in between the cosmological gamma-ray bursts and typical supernovae.

"I knew this was an exciting find because even though this was the nearest gamma-ray burst to date, the gamma-ray energy measured by Integral is one thousand times fainter than typical cosmological gamma-ray bursts," says Sergey Sazonov of the Space Research Institute, the first author of one of the two Nature papers.

The event was studied in further detail by the Chandra X-Ray Observatory and the Very Large Array, a radio telescope facility located in New Mexico.

"I was stunned that my observations from the Very Large Array showed that this event confirmed the existence of a new class of bursts," says graduate student Alicia Soderberg, who is the principal author of the other Nature paper. "It was like hitting the jackpot."

There are several exciting implications of this discovery, including the possible existence of a significant new population of low-luminosity gamma-ray bursts lurking within the nearby universe, said Shrinivas Kulkarni, who is the MacArthur Professor of Astronomy and Planetary Science at Caltech and Soderberg's faculty adviser.

"This is an intriguing discovery," says Kulkarni.

"I expect a treasure trove of such events to be identified by NASA's Swift mission scheduled to be launched this fall from Cape Canaveral. I am convinced that further discoveries and studies of this new class of hybrid events will forward our understanding of the death of massive stars."

Related Links
Space Research Institute
Caltech
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Chandra Contributes To ESA's Integral Detection Of Closest Gamma-Ray Burst
Huntsville AL (SPX) Aug 06, 2004
A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, and also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed.



Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only














The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.