Astronomers Observe a SuperNova Explode in Real-Time
For the first time a star has been observed in real-time as it goes supernova. Scientists used NASA's SWIFT satellite and a combination of orbiting and ground-based observatories to catch a supernova in the act of exploding. The event began in a star forming galaxy about 440 million light-years away toward the constellation Aries. At that time it was immediately realized that this was an unusual gamma-ray burst, about 25 times closer and 100 times longer than a typical gamma-ray burst. The burst lasted for almost 40 minutes as opposed to a typical GRB of a few milliseconds to tens of seconds. Because the burst was so long SWIFT was able to observe the bulk of the explosion with all three of its instruments: the Burst Alert Telescope, which detected the burst and relayed the location to ground observatories within 20 seconds; the X-ray telescope [XRT] and Ultraviolet/Optical Telescope [UVOT], which provides high-resolution imagery and spectra across a broad range of wavelengths.
Launched in November 2004, SWIFT detects gamma-ray burst and X-ray flashes, and relays their coordinates to the scientific community within seconds. While SWIFT rapidly re-points to continue observations with its high resolution telescopes of the decaying X-ray, UV, and optical afterglows that accompany these events, rapid follow-up observations are also be undertaken by other more powerful satellites such as Chandra, the Hubble Space Telescope or XMM satellites and by the European Southern Observatory (ESO) Very Large Telescope [VLT] and other major observatories. These powerful co-ordinated observation programmes, instigated by SWIFT, are slowly unravelling the mystery of star explosions.
"The fact that Swift can re-point very fast, slewing round to bring the XRT and UVOT to bear on the burst allowed us to get onto it very quickly indeed, enabling us to observe the critically important early behaviour of the event" remarked Dr. Alex Blustin from University College in London.
Careful, multi-wavelength analysis of space and ground-based observations has now revealed exactly what took place.
The exceptionally long burst, in the form of a jet of high-energy X-rays, pierced through the doomed star from its core and sent out a warning within minutes that a supernova was imminent. As the GRB faded away the massive star blew itself into smithereens.
"This GRB was the most extraordinary evolving object yet seen by SWIFT," said team member Dr. Paul OBrien at the University of Leicester. "The three on-board telescopes all detected a slowly brightening then fading object. The results suggest a broad jet expanded into the surroundings but it was accompanied by a slower-moving and incredibly hot - two million degree - bubble of gas produced from the shock-wave of the exploding star."
SWIFT's three telescopes - covering gamma ray, X-ray, ultraviolet and optical wavelengths - captured X-rays fading to ultraviolet and then optical light, evidence of the shock wave from the explosion pushing exploded star material into the surrounding medium.
Paul O'Brien added, "This is the first time such an extraordinary event has been seen from a GRB. The thermal component of the supernova shock wave was clearly seen in this case as the GRB itself was fairly modest, some 100 times less than a typical GRB - a mere ten million billion times the power of the Sun!"
Astronomers from the Universities of Leicester and Hertfordshire were part of a group led by Italy's National Institute for Astrophysics that used the European Southern Observatorys 8.2-metre Very Large Telescope [VLT] in Chile and the University of California's Lick Observatory Shane 3-metre telescope to obtain regularly-sampled optical spectroscopy of the shock wave. Two days later the classical supernova, a glowing cloud of gas powered by the decay of radioactive debris from the dead star, was beginning to outshine the fading shock wave.
Dr Andrew Levan, University of Hertfordshire said, "As well as studying the early evolution of the supernova for the first time these observations also show how the material ejected in the explosion evolve in the following days and weeks, the timescales on which supernovae are normally studied." Dr. Levan added, "This shows that the supernova associated with this GRB is a transition object, brighter than most supernovae in the universe, but fainter than those previously seen with GRBs. Understanding the reasons for this is a crucial step in understanding why only a small percentage of massive stars can create GRBs."
"Usually these events are not detected until after the supernova has brightened substantially in the optical wavelength, many days after the initial explosion," commented Prof. Keith Mason of the Particle Physics and Astronomy Research Council [PPARC], "but on this occasion we were able to study the remarkable event in all its glory from the very beginning."
For More Information:
http://www.pparc.ac.uk/Nw/Md/Artcl/GRB_supernova.asp
Launched in November 2004, SWIFT detects gamma-ray burst and X-ray flashes, and relays their coordinates to the scientific community within seconds. While SWIFT rapidly re-points to continue observations with its high resolution telescopes of the decaying X-ray, UV, and optical afterglows that accompany these events, rapid follow-up observations are also be undertaken by other more powerful satellites such as Chandra, the Hubble Space Telescope or XMM satellites and by the European Southern Observatory (ESO) Very Large Telescope [VLT] and other major observatories. These powerful co-ordinated observation programmes, instigated by SWIFT, are slowly unravelling the mystery of star explosions.
"The fact that Swift can re-point very fast, slewing round to bring the XRT and UVOT to bear on the burst allowed us to get onto it very quickly indeed, enabling us to observe the critically important early behaviour of the event" remarked Dr. Alex Blustin from University College in London.
Careful, multi-wavelength analysis of space and ground-based observations has now revealed exactly what took place.
The exceptionally long burst, in the form of a jet of high-energy X-rays, pierced through the doomed star from its core and sent out a warning within minutes that a supernova was imminent. As the GRB faded away the massive star blew itself into smithereens.
"This GRB was the most extraordinary evolving object yet seen by SWIFT," said team member Dr. Paul OBrien at the University of Leicester. "The three on-board telescopes all detected a slowly brightening then fading object. The results suggest a broad jet expanded into the surroundings but it was accompanied by a slower-moving and incredibly hot - two million degree - bubble of gas produced from the shock-wave of the exploding star."
SWIFT's three telescopes - covering gamma ray, X-ray, ultraviolet and optical wavelengths - captured X-rays fading to ultraviolet and then optical light, evidence of the shock wave from the explosion pushing exploded star material into the surrounding medium.
Paul O'Brien added, "This is the first time such an extraordinary event has been seen from a GRB. The thermal component of the supernova shock wave was clearly seen in this case as the GRB itself was fairly modest, some 100 times less than a typical GRB - a mere ten million billion times the power of the Sun!"
Astronomers from the Universities of Leicester and Hertfordshire were part of a group led by Italy's National Institute for Astrophysics that used the European Southern Observatorys 8.2-metre Very Large Telescope [VLT] in Chile and the University of California's Lick Observatory Shane 3-metre telescope to obtain regularly-sampled optical spectroscopy of the shock wave. Two days later the classical supernova, a glowing cloud of gas powered by the decay of radioactive debris from the dead star, was beginning to outshine the fading shock wave.
Dr Andrew Levan, University of Hertfordshire said, "As well as studying the early evolution of the supernova for the first time these observations also show how the material ejected in the explosion evolve in the following days and weeks, the timescales on which supernovae are normally studied." Dr. Levan added, "This shows that the supernova associated with this GRB is a transition object, brighter than most supernovae in the universe, but fainter than those previously seen with GRBs. Understanding the reasons for this is a crucial step in understanding why only a small percentage of massive stars can create GRBs."
"Usually these events are not detected until after the supernova has brightened substantially in the optical wavelength, many days after the initial explosion," commented Prof. Keith Mason of the Particle Physics and Astronomy Research Council [PPARC], "but on this occasion we were able to study the remarkable event in all its glory from the very beginning."
For More Information:
http://www.pparc.ac.uk/Nw/Md/Artcl/GRB_supernova.asp
