ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
Ref.: PN 08/14 (NAM 05)
Issued by RAS Press Officers:
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E-mail: rm(at)ras.org.uk
Anita Heward
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NATIONAL ASTRONOMY MEETING PRESS ROOM (31 MARCH - 4 APRIL ONLY):
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975263
975264
NAM 2008
http://nam2008.qub.ac.uk
Royal Astronomical Society
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CONTACT DETAILS ARE LISTED AT THE END OF THIS RELEASE
TWO SUPERNOVA FACTORIES FOUND IN THE MILKY WAY
The discovery of two “supernova factories”, rare clusters of Red
Supergiant (RSG) stars, located in the Galactic Bar of the Milky Way
will be presented at the RAS National Astronomy Meeting in Belfast on
Tuesday 1st April.
“RSGs represent the final brief stage in a massive star’s lifecycle
before it goes supernova. They are very rare objects, so to find this
many in the same place is remarkable. Together they contain 40 RSGs,
which is nearly 20% of all the known RSGs in the Milky Way. These stars
are all at the brink of going supernova,” said Dr Ben Davies of the
Rochester Institute of Technology.
The two clusters are located next to each other on the edge of the
Galactic Bar which is ploughing through the disc of the Milky Way. It is
likely to be this interaction between the bar and the disc that
triggered the star formation event that created the clusters.
The clusters are about 20 000 light years from Earth and separated from
each other by 800 light years. Cluster 1 contains 14 RSGs and is 12
million years old; Cluster 2 contains 26 RSGs and is 17 million years
old. Massive stars are rarely observed because they burn their fuel up
very quickly. RSGs are doubly rare because they are only a brief period
of that short life cycle.
Dr Davies said, “The next supernova could go off in one of these
clusters at any time. We estimate that it’s about 5000 years between
explosions for these clusters and we can see the remnants of a supernova
that went off around 5000 years ago. That means that the next one could
be any time between today and 7008 AD.”
The team identified the clusters initially using the mid-infrared
Galactic Plane survey (GLIMPSE), a huge database of images taken by the
Spitzer Space Telescope. They found two distinct groupings of bright
stars very close to one another in the constellation of Scutum. Using
the Keck Telescope in Mauna Kea, Hawaii, they were then able to
pin-point the exact distance from Earth of each star in each group.
These observations showed that, in each group, large numbers of stars
were at exactly the same distance from Earth, and therefore were members
of the same cluster.
Dr Davies said, “The discovery of these clusters gives us a great
opportunity to answer some long-standing questions in astrophysics, such
as exact mechanisms of how massive stars evolve toward supernovae, and
how the Galactic Bar can trigger huge starburst events in the Milky Way.”
IMAGES
Images can be found at http://www.cis.rit.edu/~bxdpci/RSGCimages
NOTES FOR EDITORS
RAS NATIONAL ASTRONOMY MEETING
The RAS National Astronomy Meeting (NAM 2008) is hosted by Queen’s
University Belfast. It is principally sponsored by the RAS and the STFC.
NAM 2008 is being held together with the UK Solar Physics (UKSP) and
Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring meetings.
RED SUPERGIANTS (RSGs)
Red Supergiants are approximately 14-18 times the mass of the Sun.
Their diameters are many hundreds of times the diameter of the Sun and
around a million Suns could fit inside one RSG.
Image 1: Colour composite of Cluster 1. Blue represents hot interstellar
gas, stars show up as green and hot dust shows as red. The RSGs are the
bright stars in the centre.
Image 2: Top-down illustration of the Milky Way, showing the Bar and the
location of the clusters.
CONTACTS
Dr Ben Davies
Center for Imaging Science
Rochester Institute of Technology
54 Lomb Memorial Drive
Rochester, NY 14623
USA
Phone: (+1) 585-475-2338
E-mail: davies(at)cis.rit.edu
From Monday 31st March to Friday 4th April Dr Davies can be contacted
through the NAM press office (see top of release for details)
