Flash in the sky appears and disappearsSeptember 25th, 2008 - 2:23 pm ICT by IANS
London, Sep 25 (IANS) Astronomers have discovered a bizarre celestial object that emitted 40 flashes of light before disappearing again. Described as a hibernating stellar magnet, this weird object initially misled its discoverers showing up as a gamma-ray burst, suggesting the death of a star in a distant part of the universe.
After the initial gamma-ray pulse, there was a three-day active phase during which 40 visible-light flares were observed, followed by a brief near-infrared flaring episode 11 days later, recorded by ESO’s Very Large Telescope. Then the source became dormant again.
ESO is European Organisation for Astronomical Research in the Southern Hemisphere, based near Munich in Germany.
“We are dealing with an object that has been hibernating for decades before entering a brief period of activity,” explained Alberto J. Castro-Tirado of the ESO and co-author of a paper on the subject that has been published in this week’s issue of Nature.
Construed as a likely missing link in the family of neutron stars, it is the first of an object with an ultra powerful magnetic field that showed some brief, strong visible-light activity.
The most likely candidate for this mystery object is a ‘magnetar’ located in our own Milky Way galaxy, about 15,000 light-years away towards the constellation of Vulpecula, the Fox, according to an ESO release.
Magnetars are young neutron stars with an ultra-strong magnetic field a billion billion times stronger than that of the Earth. “A magnetar would wipe the information from all credit cards on Earth from a distance halfway to the Moon,” said co-author Antonio de Ugarte Postigo of the ESO.
Some scientists have noted that magnetars should be evolving towards a pleasant retirement as their magnetic fields decay, but no suitable source had been identified up to now as evidence for this evolutionary scheme.
Magnetars are very tiny neutron stars with magnetic fields hundreds of times more intense than the average neutron star fields. The energy released during a single flare can be equal to that released by the Sun in 10,000 years.