In 2012, a bright supernova appeared in the sky toward the constellation of Leo. This supernova, which was later called SN 2012a, is pictured in the image above, taken by Adam Block of the Mount Lemmon Sky Center.
Also pictured is SN 2012a’s host galaxy, NGC 3239: a bright, blue-tinged irregular galaxy located approximately 25 million light-years from Earth (numerous more distant galaxies can be seen to the left and right). Otherwise known as Arp 263, astronomers believe many of its peculiar characteristics are the result of a gravitational merger of some kind, whereby another galaxy wandered too close, and left a lasting impression.
One of the strangest qualities the merger likely left behind can be traced throughout the galaxy itself—an alignment between regions where active star formation is taking place (HII regions), and hot blue-white star clusters.
The brightest point of light in this field of view isn’t found within the confines of NGC 3239. Rather, it’s a foreground star belonging to the Milky Way galaxy. Its much closer proximity makes it appear larger in comparison.
See a larger image here.