

Even finding these pulsars is extremely difficult - and the new discovery
could throw light on these mysterious cosmic objects. Heartbeat of the
universe pulsars are the 'beacons' of space - tiny, burnt out stars, which
emit regular pulses of gamma rays - regular, that is, until scientists found
one with hiccups.
A pulsar star, circled by the remnants of planets and solar
material, drifts through the vacuum of space (file picture) Pulsars form when a
star becomes unstable and goes supernova - first of all compressing into a tiny
space before exploding. The explosion sheds almost all the material of the star
off into the vacuum of space at almost ten per cent the speed of light.
All
that is left is a tiny, spinning core - the pulsar - which rotates at
astonishing speed, perhaps just seconds. As they spin, it sends off highly
concentrated beams of radio-waves, which to a distant stationary observer (for
instance on Earth) appear to flash on and off in a regular pattern - the pulse
of the pulsar star.The odd new star was found as astronomers sifted
astronomical data with supercomputers. 'By employing new optimal algorithms on
our ATLAS computer cluster, we were able to identify many previously-missed
signals,' says Bruce Allen, Director of the AEI. Back in November 2011, Allen's
team announced the discovery of nine new Fermi gamma-ray pulsars, which had
escaped all previous searches. Now the scientists have made a new extraordinary
find with the same methods.


The name of the newly discovered pulsar – J1838-0537 – comes from its
celestial coordinates. 'The pulsar is, at 5,000 years of age, very young. It
rotates about its own axis roughly seven times per second and its position in
the sky is towards the Scutum constellation,' says Holger Pletsch, a scientist
in Allen's group and lead author of the study which has now been published.
'After the discovery we were very surprised that the pulsar was initially only
visible until September 2009. Then it seemed to suddenly disappear.' Only a
complex follow-up analysis enabled an international team led by Pletsch to
solve the mystery of pulsar J1838-0537: it did not disappear, but experienced a
sudden glitch after which it rotated 38 millionths of a Hertz faster than
before. 'This difference may appear negligibly small, but it's the largest
glitch ever measured for a pure gamma-ray pulsar.' The pulsar J1838-0537
suddenly speed-ed up the rays it was blasting into space - and 'glitched', in a
cosmic hiccup that scientists still don't understand.
The precise cause of the
glitches observed in many young pulsars is unknown. Astronomers consider
"star quakes" of the neutron star crust or interactions between the
superfluid stellar interior and the crust to be possible explanations. 'Detecting a large number of strong
pulsar glitches makes it possible to learn more about the inner structure of
these compact celestial bodies,' says Lucas Guillemot from the Max Planck
Institute for Radio Astronomy in Bonn, the second author of the study.'


No comments:
Post a Comment