Symmetry of supernova's remnants can reveal how the star exploded

Washington, December 18 (ANI): A new study of images from NASA's Chandra X-ray Observatory on supernova remnants shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded.

This is an important discovery because it shows that the remnants retain information about how the star exploded even though hundreds or thousands of years have passed.

"It's almost like the supernova remnants have a 'memory' of the original explosion," said Laura Lopez of the University of California at Santa Cruz, who led the study.

"This is the first time anyone has systematically compared the shape of these remnants in X-rays in this way," she added.

Astronomers sort supernovas into several categories, or "types", based on properties observed days after the explosion and which reflect very different physical mechanisms that cause stars to explode.

But, since observed remnants of supernovas are leftover from explosions that occurred long ago, other methods are needed to accurately classify the original supernovas.

Lopez and colleagues focused on the relatively young supernova remnants that exhibited strong X-ray emission from silicon ejected by the explosion so as to rule out the effects of interstellar matter surrounding the explosion.

Their analysis showed that the X-ray images of the ejecta can be used to identify the way the star exploded.

The team studied 17 supernova remnants both in the Milky Way galaxy and a neighboring galaxy, the Large Magellanic Cloud.

For each of these remnants there is independent information about the type of supernova involved, based not on the shape of the remnant but, for example, on the elements observed in it.

The researchers found that one type of supernova explosion - the so-called Type Ia - left behind relatively symmetric, circular remnants.

This type of supernova is thought to be caused by a thermonuclear explosion of a white dwarf, and is often used by astronomers as "standard candles" for measuring cosmic distances.

On the other hand, the remnants tied to the "core-collapse" supernova explosions were distinctly more asymmetric.

This type of supernova occurs when a very massive, young star collapses onto itself and then explodes.

"If we can link supernova remnants with the type of explosion, then we can use that information in theoretical models to really help us nail down the details of how the supernovas went off," said co-author Enrico Ramirez-Ruiz, also of University of California, Santa Cruz. (ANI)