Jan 8, 2009

Science - New movie shows changes in time in famous supernova remnant

Washington, Jan 7 (ANI): A new movie of data from NASA's Chandra X-ray Observatory shows changes in time never seen before in a famous supernova remnant.

Nearly ten years ago, Chandra's "First Light" image of Cassiopeia A (Cas A) revealed previously unseen structures and detail.

Now, after eight years of observation, scientists have been able to construct a movie that tracks the remnant's expansion and changes over time.

"With Chandra, we have watched Cas A over a relatively small amount of its life, but so far the show has been amazing," said Daniel Patnaude of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. "And, we can use this to learn more about the aftermath of the star's explosion," he added.

Based on data from Chandra, NASA's Spitzer Space Telescope, and ground-based optical telescopes, Tracey Delaney and her colleagues have created the first three-dimensional fly-through of a supernova remnant.

"We have always wanted to know how the pieces we see in two dimensions fit together with each other in real life," said Delaney of the Massachusetts Institute of Technology. "Now we can see for ourselves with this 'hologram' of supernova debris," she added.

"Right now, we are focusing on improving three-dimensional visualization in both astronomy and medicine," said Harvard's Alyssa Goodman, who heads the project. "This project with Cas A is exactly what we have hoped would come out of it," she added.

While these are stunning visuals, both the data movie from Patnaude and the 3-D model from Delaney are, more importantly, rich resources for science.

Patnaude and his team have measured the expansion velocity of features in Cas A from motions in the movie, and find it is slower than expected based on current theoretical models.

According to Patnaude, the explanation for this mysterious loss of energy is cosmic ray acceleration.

Using estimates of the properties of the supernova explosion, including its energy and dynamics, Patnaude's group show that about 30 percent of the energy in this supernova has gone into accelerating cosmic rays, energetic particles that are generated, in part, by supernova remnants and constantly bombard the Earth's atmosphere.

The flickering in the movie provides valuable new information about where the acceleration of these particles occurs.

Likewise, the new 3-D model of Cas A provides researchers with unique ability to study this remnant.

With this new tool, Delaney and colleagues found two components to the explosion, a spherical component from the outer layers of the star and a flattened component from the inner layers of the star. (ANI)

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