Researchers focusing on an inset of the central region of NGC 5194 saw bright clouds of hot gas, with temperatures in the multi-millions of degrees, extending to the north and south of the nucleus of the galaxy. The gaseous extensions have diameters of about 1,500 light years and 500 light years, respectively, Their likeness to similar branches observed at radio wavelength suggests they are heated by the high-velocity jets of a supermassive black hole in the heart of the galaxy.

The lower left area of the inset image is a faint source that scientists determined was an unusual Type Ic supernova. Researchers identified it using a supernova discovered by amateur astronomers from Georgia in 1994. The massive stars responsible for these supernovas are thought to have lost their outer layers of hydrogen and helium gas thousands of years before they ultimately exploded, either through evaporation or transfer to a companion star.

In the millennia before a doomed star explodes into a supernova, it loses mass. X-ray observations of the supernova shock wave provide a method to sensitively probe this process. The Chandra data from the 1994 supernova and its surrounding area indicate that the star that caused it evaporated material into a cloud spanning at least 0.2 light years in diameter. Further monitoring of the system over the next few years will allow researchers to observe the cloud's exact size and determine how long it took it to lose its mass before exploding.

Astronomer Andrew Wilson of the University of Maryland, in College Park, was the principal investigator for Chandra's Whirlpool Galaxy observations. Other participants in the study include Yuichi Terashima, also at Maryland, and Stefan Immler of the University of Massachusetts, Amherst.