This image of the core of NGC 5194, the larger of two interacting galaxies called the Whirlpool, for the first time provides an X-ray portrait of a rare, so-called Ic supernova (box). The massive stars that end their lives as Ic supernovas have companion stars and shed their outer layers of hydrogen and helium gas thousands of years before they explode. Astronomers hadn't known whether the gases had been snared by the companion star or ejected by a strong stellar wind. Data from NASA's Chandra X-ray Observatory suggest the latter because they indicate that the blast wave from the supernova had slammed into material left behind by such a wind.
Stefan Immler of the University of Massachusetts in Amherst and Andrew S. Wilson and Yuichi Terashima of the University of Maryland in College Park report this and other findings