Supernova Explosion captured in 'real time'

[Pastor Dale Morgan]

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Signs In The Sun, The Moon and The Stars

Supernova Explosion captured in 'real time'*

BBC - Astronomers say they have witnessed a stellar explosion - or
supernova - unfolding in real time.

Supernovae occur when a huge, mature star effectively runs out of fuel
and collapses in on itself.

Their observations, outlined in the journal Nature, offer the most
detailed picture yet of these cosmic explosions.

An initial release of energy from the star was picked up by the US Swift
satellite in February, allowing experts to train their telescopes on the
event.

This short, sharp outburst, known as an X-ray flash, is effectively an
early warning signal that the star was going to turn supernova.

Swift is designed to look out for gamma-ray bursts (GRBs), intense
energetic outbursts of radiation thought to arise from the collapse of
massive stars in a supernova. However, not all supernovae generate GRBs,
and it remains unclear what causes some but not others to produce these
bursts.

Compact remnant

An X-ray flash can be regarded as a less energetic form of GRB. It was
previously unclear whether these less energetic events were generated by
the same process of stellar collapse during a supernova. The latest
results seem to confirm that link.

The release of energy that occurs in the X-ray flash lasts for about 15
minutes and is followed by a day-long "breakout" phase, in which the
shockwave breaches the surface of the collapsing star, unleashing its
energy.

Supernova SN2006aj Image: European Southern Observatory (Eso)

The stellar explosion occurred 400 million light years away

This expands into space as radiation at all frequencies and lasts for a
period of days to months - the classic signature of a supernova.

Four groups of astronomers gathered data on the event, and publish
separate research papers in Thursday's issue of Nature.

"Those observations capture the time when the star collapsed, ejected
its outer envelope and most of its mass and left a compact remnant
behind. And we think that compact remnant is a neutron star," said Paolo
Mazzali, one of the authors who is based at the Max-Planck Institute in
Garching, Germany.

Analysis of the expanding debris suggests the initial star had a lower
mass than is the norm for such explosions. Gamma-ray bursts are thought
to be associated with the collapse of a star into a black hole. But
lower mass stars are thought to collapse into a compact object known as
a neutron star.

So what powered the X-ray flash and shockwave? The researchers think
these were produced by magnetic energy supplied by a highly magnetised
object at the core of the star called a magnetar.