Star Formation may spread 'Like a Bushfire'
Star formation may jump from place to place inside
a galaxy like a
bushfire front, according to a team of astronomers
from the UK,
Australia and Spain. The team used the Hubble
Space Telescope and other
telescopes to study a galaxy called NGC 2903,
which lies 25 million
light-years away and is similar to our own galaxy.
The HST picture shows that known 'hot spots' near
the centre of the
galaxy are clusters of stars born 5 to 10 million
years ago. Other
spots in the galaxy are clouds of ionised hydrogen
gas where young
stars are forming today.
The two kinds of spots are far apart, meaning
activity is shifting from place to place.
"It's moving surprisingly fast, about a million
kilometres a year on
average," says team member Dr Stuart Ryder of
Observatory in Sydney.
Stars form when a giant cloud of cold hydrogen
gas collapses in on
"Star formation may be like a bushfire," says
Dr Ryder. "Once it has
burnt out an area, it has to move on to where
there's more fuel, or it
will die out."
"Perhaps when one cloud of gas is used up by being
turned into stars,
the star-forming process starts in a neighbouring
triggered by shock waves from stars exploding
The astronomers also found that a dense region
of stars in the galaxy,
called a bar, seems to funnel gas into the galaxy's
the birth of young stars.
"The centre of this galaxy is like a retirement
village," Dr Ryder
says. "Most of the stars are old. But we see
a bit more action in
places - a couple of discos starting up. That
means there are some
younger inhabitants as well."
The research team members are Almudena Alonso-Herrero
Hertfordshire, UK), Stuart D. Ryder (Anglo-Australian
Sydney, Australia) and Johan H. Knapen (Isaac
Newton Group of
Telescopes, Spain and the University of Hertfordshire,
The research results are described in Alonso-Herrero
et al. (2001)
available at http://arXiv.org/format/astro-ph/0010522.
The paper will
be published in a forthcoming issue of Monthly
Notices of the Royal
The Hubble Space Telescope is a project of international
between the European Space Agency and NASA.
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Image credit: ESA & NASA
Dr Stuart Ryder, Anglo-Australian Observatory,
Dr Almudena Alonso-Herrero, University of Hertfordshire,
(presently travelling in India)
Dr Johan H. Knapen, Isaac Newton Group of Telescopes,
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