Star Explodes and Turns Inside-Out in Supernova Explosion
Posted on April 1, 2012
A new X-ray study of the remains of an exploded star indicates that the supernova that disrupted the massive star may have turned it inside out in the process. Scientists made long observations of Cassiopeia A and mapped the distribution elements in the supernova remnant. The information shows where the different layers of the pre-supernova star are located three hundred years after the explosion.
The artist's illustration (the top image) shows a simplified picture of the inner layers of the star that formed Cassiopeia A just before it exploded. The predominant concentrations of different elements are represented by different colors. For example, iron in the core is blue. The image from NASA's Chandra X-ray Observatory above uses the same color scheme to show the distribution of elements in the supernova remnant. The data shows that the distributions of sulfur and silicon are similar, as are the distributions of magnesium and neon. Most of the iron is now located near the outer edges of the remnant. There is no evidence from X-ray (Chandra) or infrared (Spitzer Space Telescope) observations for iron near the center of the remnant, where it was formed. Also, much of the silicon and sulfur, as well as the magnesium, is now found toward the outer edges of the still-expanding debris. The distribution of the elements indicates that a strong instability in the explosion process turned the star inside out.
The astronomers found clumps of almost pure iron, indicating that this material must have been produced by nuclear reactions near the center of the pre-supernova star, where the neutron star was formed. The existence of pure was anticipated because a signature of this type of nuclear reaction is the formation of the radioactive nucleus titanium-44, or Ti-44.
This first video shows how the innermost elements become located on the outer edges of the star remnant. The second video shows a movie of observations of Cassiopeia A over eight years. Both videos are from the Chandra X-Ray Observatory. Take a look:
These results appeared in the February 20th issue of The Astrophysical Journal in a paper by Una Hwang of Goddard Space Flight Center and Johns Hopkins University, and (John) Martin Laming of the Naval Research Laboratory.