RAS PN 08/39: Astronomers find youngest supernova remnant in Milky Way
ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE
EMBARGOED UNTIL 1800 BST, 14 May 2008
Date: 13 May 2008
Ref.: PN 08/39
Issued by RAS Press Officer:
Dr Robert Massey
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Royal Astronomical Society
RAS PN 08/39 (EMBARGOED): ASTRONOMERS FIND YOUNGEST SUPERNOVA REMNANT IN MILKY WAY
An international team of astronomers have found the youngest known supernova remnant in the Galaxy. Using observations made with the Very Large Array (VLA) radio telescope in the US and the orbiting Chandra X-ray observatory, the scientists report that the remnant, G1.9+0.3, is just 150 years old. University of Cambridge scientist Dr Dave Green and colleagues discuss the discovery in a paper to be published in the journal Monthly Notices of the Royal Astronomical Society.
A supernova remnant (SNR) is the material ejected by a supernova, the explosion at the end of the life of a star much more massive than the Sun. In our own Galaxy, the Milky Way, there are about 250 known SNRs and up to now the youngest was thought to be about 340 years old.
Scientists including Dr Green and Dr Stephen Reynolds of North Carolina State University compared an X-ray image of G1.9+0.3 made using the Chandra satellite in 2007 with a radio image made with the VLA in 1985. They found that the SNR expanded considerably over the two decades, indicating it is very young. But the team were not sure whether some of the differences between the X-ray and radio images of G1.9+0.3 simply arose from comparing images made at very different frequencies from very different instruments.
To check their result, the team used the VLA to observe the SNR for a second time so that a direct comparison could be made with the 1985 image. The new observations confirm that G1.9+0.3 is expanding at an unprecedented rate, increasing its size by 15% in the intervening 23 years. Extrapolating backwards in time confirms G1.9+0.3 to be at most 150 years old, which makes it easily the youngest known SNR in our Galaxy and the only one that has been seen at such an early stage of its evolution. Another property of G1.9+0.3 that marks it out as unusual is that, uniquely among Galactic SNRs, it appears to have been increasing in radio brightness over the last few decades.
Although the distance to G1.9+0.3 is not known precisely, it is probably near the centre of our Galaxy. The SNR is obscured by a large amount of gas and dust, which means that Victorian astronomers would not have been able to see the explosion when it took place in the 1850s. Today scientists can observe the X-ray and radio emission from the ongoing aftermath of the explosion, as these penetrate the obscuring material.
Dr Green is delighted to have found such a young SNR. He comments "The discovery that G1.9+0.3 is so young is very exciting. It fits into a large gap in the known ages of supernova remnants, and since it is expanding so quickly, we will be able to follow its evolution over the coming years.”
FURTHER INFORMATION (INCLUDING IMAGES):
Radio images of supernova remnant G1.9+0.3
National Radio Astronomy Observatory (for VLA information)
Chandra home page
RAS home page
NOTES FOR EDITORS
The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
Dr Dave Green
19 J. J. Thomson Avenue
Cambridge CB3 0HE
Tel: +44 (0)1223 337305
Dr Stephen Reynolds
North Carolina State University
North Carolina 27695
Tel: +1 919 515 7751
Dr Dave Finley
Public Information Officer
National Radio Astronomy Observatory
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