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  Chandra X-ray Observatory Study of Vela Shrapnel A


A supernova is a spectacular energy outburst caused by an explosive disruption of a star, making the end of its life. Such stellar deaths are nature's most energetic single events, creating truly impressive celestial fireworks. Supernovae have typical kinetic energy releases of 1051 erg and total energy releases of up to 1053 erg. The resulting shock waves can heat and accelerate the surrounding gas and the emission from this gas identifies supernova remnants (SNRs).

The Vela SNR is one of the nearest and biggest SNRs. The Rosat satellite revealed the whole X-ray image of the Vela SNR and found that six extended X-ray objects outside the shock wave front. These objects show the 'boomerang' type structure which opens toward the SNR center. The symmetry axes of these six objects intersect each other close to the remnant's geometric center, strongly suggests their identical origin. This means these protruding objects are debris of exploded star, which are ejected at supernova explosion.If it is the case, these objects show a metal-rich composition synthesized during the explosion.

We have observed one of the brightest object (shrapnel A) with the Chandra X-ray Observatory. The superb imaging capability of Chandra enables us to reveal the bright knot structure and extended tailing emission toward the center of the Vela SNR. We detected a strong emission line from silicon. Abundance of silicon is much larger than that of the interstellar medium and abundance ratio of heavy elements is anomalous. These facts strongly suggest that the view that shrapnel A is debris of the exploded star created in the supernova explosion.

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