- Outflows contain an extraordinary amount of energy — about a million times that of an exploding star
- Believed to be caused by 'star power' from many generations of exploding stars
- Researchers say they pose no harm to Earth - but could be crucial to magnetic fields
- Seen from Earth, the outflows stretch about two-thirds across the sky from horizon to horizon
Mysterious 'monster' outflows of charged particles
from the centre of our Galaxy, stretching more than halfway across the sky,
have been detected by astronomers.
Researchers say they contain an 'extraordinary'
amount of energy - but stress they pose no harm to us.
The researchers were able to map the cosmic 'geysers'
of gas.
The giant cosmic geysers were..
mapped mapped with CSIRO's 64-m Parkes radio telescope in Australia, and the outflows were detected by astronomers from Australia, the USA, Italy and The Netherlands.
mapped mapped with CSIRO's 64-m Parkes radio telescope in Australia, and the outflows were detected by astronomers from Australia, the USA, Italy and The Netherlands.
The finding is reported in today's issue of Nature.
'These outflows contain an
extraordinary amount of energy — about a million times the energy of an
exploding star," said the research team's leader, CSIRO's Dr Ettore
Carretti.
But the outflows pose no danger to Earth or the
Solar System.
The speed of the outflow is supersonic, about 1000
kilometres a second.
'That's fast, even for
astronomers," Dr Carretti said.
'They are not coming in our direction,
but go up and down from the Galactic Plane.
'We are 30,000 light-years away from
the Galactic Centre, in the Plane. They are no danger to us.'
From top to bottom the outflows extend 50,000
light-years [five hundred thousand million million kilometres] out of the
Galactic Plane.
Seen from Earth, the outflows stretch about
two-thirds across the sky from horizon to horizon.
The outflows correspond to a 'haze' of
microwave emission previously spotted by the WMAP and Planck space telescopes
and regions of gamma-ray emission detected with NASA's Fermi space telescope in
2010, which were dubbed the 'Fermi Bubbles'.
However, the the WMAP, Planck and Fermi observations did not provide enough evidence to indicate definitively the source of the radiation they detected, but the new Parkes observations do.
However, the the WMAP, Planck and Fermi observations did not provide enough evidence to indicate definitively the source of the radiation they detected, but the new Parkes observations do.
'The options were a quasar-like
outburst from the black hole at the Galactic Centre, or star-power — the hot
winds from young stars, and exploding stars,' said team member Dr Gianni Bernardi of
the Harvard-Smithsonian Center for Astrophysics, in Cambridge, Massachusetts.
'Our observations tell us it's
star-power.'
In fact, the outflows appear to have been driven by
many generations of stars forming and exploding in the Galactic Centre over the
last hundred million years.
The key to determining this was to measure the
outflows' magnetic fields.
'We did this by measuring a key
property of the radio waves from the outflows — their polarisation,' said team member Dr
Roland Crocker of the Max-Planck-Institut fuer Kernphysik in Heidelberg,
Germany, and the Australian National University.
The new observations also help to answer one of
astronomers' big questions about our Galaxy: how it generates and maintains its
magnetic field.
'The outflow from the Galactic Centre
is carrying off not just gas and high-energy electrons, but also strong
magnetic fields,' said team member Dr Marijke Haverkorn of Radboud University Nijmegen in
The Netherlands.
'We suspect this must play a big part
in generating the Galaxy's overall magnetic field.'
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