Youngest Supernova in Milky Way Found

May 14, 2008

Scientists have peered through a thick shroud of interstellar dust to reveal the youngest supernova ever seen in the Milky Way.

Stephen Reynolds, an astrophysicist at North Carolina State University, and his team suspected that supernova G1.9+0.3 was very young.

So they compared 2007 images of the object from NASA's Chandra X-Ray Observatory with radio observations from the mid-1980s—and their suspicions were confirmed.

Estimated at just 140 years old, G1.9+0.3 is at least 200 years younger than the next oldest known supernova, Cassiopeia A, which was discovered in the 17th century A.D.

"Cas A had been the reigning youngest remnant for so long that it took a while to sink in that we had found something less than half its age," Reynolds said.

If it weren't so obscured by dust, people in the late 1800s would likely have seen G1.9+0.3 appear in the constellation Sagittarius.

As it is, G1.9+0.3—located about 26,000 light-years away—is still expanding at a surprisingly fast rate, and its discovery may pave the way to a greater understanding of exploding stars.

The results will appear in the June 10 edition of Astrophysical Journal Letters.

Galaxy Drivers

Supernovas, or exploding stars, are believed to help drive the life cycles of galaxies. A supernova explosion disperses heavy metals, as well as cosmic rays and high-energy particles that fuel the formation of new stars. (Related: "Brightest Known Supernova Detected" [October 15, 2007].)

The brightness of supernova remnants (SNRs) can easily be obscured from optical telescopes by gas and dust, but are usually visible to x-ray and radio telescopes.

Astronomers have been puzzled, however, by a shortage of young supernova remnants in our galaxy. Only half a dozen have been found, as opposed to the more than 30—roughly two a century—predicted to exist.

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