NASA has released an image of a supernova (SN 2004dg) that occurred in NGC 5806, a spiral galaxy in the constellation Virgo (the Virgin) located approximately 80 million light years from Earth.
The combined image exposures snapped by the Hubble Space Telescope were actually stitched together in early 2005 to help pinpoint the location of the supernova, which apparently exploded in 2004. The afterglow from this outburst of light, caused by a giant star exploding at the end of its life, can be seen as a faint yellowish dot near the bottom of the galaxy.
NGC 5806 was chosen as part of a recent supernovae study because Hubble’s archive already contained high resolution imagery of the galaxy, collected before the star had exploded. As supernovae are both relatively rare, and impossible to predict with any accuracy, the existence of such before-and-after images is quite useful for astronomers studying such events.
Aside from the supernova, NGC 5806 is a relatively unremarkable galaxy: it is neither particularly large or small, nor especially close or distant.
The galaxy’s bulge (the densest part in the center of the spiral arms) is a so-called disk-type bulge, in which the spiral structure extends right to the center of the galaxy, instead of there being a large elliptical bulge of stars present. It is also home to an active galaxy nucleus, a supermassive black hole which is pulling in large amounts of matter from its immediate surroundings. As the matter spirals around the black hole, it heats up and emits powerful radiation.
This image is produced from three exposures in visible and infrared light, observed by Hubble’s Advanced Camera for Surveys. The field of view is approximately 3.3 by 1.7 arcminutes.