[ASC-media] Monster star blast 'brighter than full Moon'

Helen Sim Helen.Sim at csiro.au
Sat Feb 19 08:48:26 EST 2005

Issued by: Helen Sim
CSIRO Australia Telescope National Facility
+61-419-635-905 (mob.)
Helen.Sim at csiro.au


19 February 2005
For immediate use


Australian radio telescopes of CSIRO and the University of Sydney, and
others in Europe, India and the USA, have been watching the aftermath of one
of the most stupendous cosmic explosions ever recorded.

On 27 December last year a star 50 000 light-years away produced a monster
blast of radiation that made it, for a tenth of a second, brighter than the
full Moon ‹ the brightest object ever seen outside the solar system ‹ and
briefly disrupted a layer of the Earth¹s atmosphere.

The event was detected by X-ray and gamma-ray instruments on NASA and
European satellites, and by telescopes around the world.

The observations were presented at a NASA press briefing in Washington today
(0600 AEDT). Papers on the event will appear in the journal Nature.

This Œgiant flare¹ came from a highly magnetised neutron star, or magnetar,
called SGR 1806-20. It may have resulted from an eruption on the star¹s
surface, like a solar flare from the Sun, or from a quake in the solid
surface of the neutron star. Either way, it unleashed 10exp40 watts, putting
out more energy in a tenth of a second than the Sun emits in 100 000 years.

³Essentially, this was a mini gamma-ray burst in our backyard,² said Dr.
Bryan Gaensler of the Harvard-Smithsonian Center for Astrophysics, who led
the radio observations. ³It may be a once per century or once per millenium
event in our Galaxy.²

³Had this happened within 10 light-years of us, it would have severely
damaged our atmosphere and possibly have triggered a mass extinction.
Fortunately there are no magnetars anywhere near us,² he says.

The nearest known magnetar, 1E 2259+586, is about 13 000 light-years away.

CSIRO¹s Australia Telescope Compact Array started observing SGR 1806-20 on 5
January; the University of Sydney¹s Molonglo Observatory Synthesis Telescope
(MOST) began on 6 January.

>From the characteristics of the radio emission astronomers have been able to
confirm how much energy the explosion released, the physical processes
involved and the geometry of the event.

³The Compact Array is a uniquely versatile and flexible instrument,² says
Gaensler. ³It was able to observe at frequencies other telescopes couldn¹t,
which allowed us to fill in the full radio Œrainbow¹.²

The first week of observations at the Compact Array were made by Katherine
Newton-McGee, a University of Sydney astrophysics student who has just
completed the first year of her PhD.

³It was very exciting ‹ this was a hundred times larger than any such burst
ever seen before.²

Katherine is studying cosmic magnetic fields for her PhD, ³so the magnetar
was relevant², she says.

Other observing at the Compact Array was done by Yosi Gelfand, a PhD student
at the Harvard-Smithsonian Center for Astrophysics, and staff of CSIRO¹s
Australia Telescope National Facility.

³The MOST got the best low-frequency observations,² says the University of
Sydney¹s Professor Dick Hunstead. ³They confirmed that the radio source must
have expanded very rapidly early on.²

SGR 1806-20 is three thousand million times further away than the Sun. ³That
it can reach out and tap us on the shoulder like this, reminds us that we
really are linked to the cosmos,² says Dr. Phil Wilkinson of IPS Australia,
which monitors Œspace weather¹ and its effects on the Earth¹s atmosphere.






Bryan Gaensler, Harvard-Smithsonian Center for Astrophysics
+1-617-869-7153 (mob.)
+1-617-496-7854 (office)
bgaensler at cfa.harvard.edu
NOTE: ring any day up until 1400 AEDT or email and ask for call back.

Dr Bob Sault, CSIRO Australia Telescope National Facility
+61-2-6790-4050 (observatory, direct)
+61-2-6790-4000 (observatory, main)
+61-429-904-051 (mob.)
Bob.Sault at csiro.au

Dr Simon Johnston, CSIRO Australia Telescope National Facility
+61-2-9372-4573 (office)
+61-2-9869-2944 (home)
Simon.Johnston at csiro.au

Dr Dick Hunstead, University of Sydney
+61-2-9351-3871 (office)
+61-2- 9999 1847 (home)
rwh at physics.usyd.edu.au

Dr Phil Wilkinson, IPS Australia
+61-2-9213-8003 (office)
+61-417-508-003 (mob.)
phil at ips.gov.au

Katherine Newton-McGee, University of Sydney
+61-414-449-269 (mob)
+61-2-9351-5577 (office)
katnm at physics.usyd.edu.au

Dr Brian Schmidt, Research School of Astronomy and Astrophysics, ANU (for
independent comment)
+61-2-6125-8042 (office)
+61-408-383-365 (mob.)
brian at mso.anu.edu.au

Dr Andrew Melatos, University of Melbourne (for independent comment)
+61-3-8344-5436 (office)
a.melatos at physics.unimelb.edu.au

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