Youngest-known supernova remnants discovered
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Last Updated: Saturday, March 16, 2013, 21:40
  
Washington: NASA's Swift satellite has uncovered the previously unknown remains of a shattered star while performing an extensive X-ray survey of our galaxy's central regions.

Designated G306.3-0.9 after the coordinates of its sky position, the new object ranks among the youngest-known supernova remnants in our Milky Way galaxy.

"Astronomers have previously cataloged more than 300 supernova remnants in the galaxy," lead scientist Mark Reynolds, a postdoctoral researcher at the University of Michigan in Ann Arbor said.

"Our analysis indicates that G306.3-0.9 is likely less than 2,500 years old, making it one of the 20 youngest remnants identified," he said.

Astronomers estimate that a supernova explosion occurs once or twice a century in the Milky Way.

The expanding blast wave and hot stellar debris slowly dissipate over hundreds of thousands of years, eventually mixing with and becoming indistinguishable from interstellar gas.

A wider view places G306.3-0.9 in context with star-formation regions in southern Centaurus.

Like fresh evidence at a crime scene, young supernova remnants give astronomers the best opportunity for understanding the nature of the original star and the details of its demise.

Supernova remnants emit energy across the electromagnetic spectrum, from radio to gamma rays, and important clues can be found in each energy band.

X-ray observations figure prominently in revealing the motion of the expanding debris, its chemical content, and its interaction with the interstellar environment, but supernova remnants fade out in X-ray light after 10,000 years.

Indeed, only half of those known in the Milky Way galaxy have been detected in X-rays at all.

Reynolds leads the Swift Galactic Plane Survey, a project to image a two-degree-wide strip along the Milky Way's central plane at X-ray and ultraviolet energies at the same time. Imaging began in 2011 and is expected to complete this summer.

To further investigate the object, the team followed up with an 83-minute exposure using NASA's Chandra X-ray Observatory and additional radio observations from the Australia Telescope Compact Array (ATCA), located near the town of Narrabri in New South Wales.

Using an estimated distance of 26,000 light-years for G306.3-0.9, the scientists determined that the explosion's shock wave is racing through space at about 1.5 million mph (2.4 million km/h).

The Chandra observations reveal the presence of iron, neon, silicon and sulfur at temperatures exceeding 50 million degrees F (28 million C), a reminder not only of the energies involved but of the role supernova e play in seeding the galaxy with heavy elements produced in the hearts of massive stars.

The findings are set to be published in The Astrophysical Journal.

ANI


First Published: Saturday, March 16, 2013, 21:40


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