Hubble Spots Supernova in Distant Galaxy

The Hubble team has released a new image of NGC 5806, a barred spiral galaxy in the constellation Virgo.

The image shows the barred spiral galaxy NGC 5806 with the supernova SN 2004dg, circled. NGC 5806, found in the constellation Virgo, is located approximately 80 million light years from Earth (ESA / NASA / Andre van der Hoeven)

The exposures that are combined into the image were carried out in early 2005 in order to help pinpoint the location of the supernova SN 2004dg, which 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.

The galaxy was chosen to be one of a number of galaxies in a study into supernovae because Hubble’s archive already contained high resolution imagery of the galaxy, collected before the star had exploded. Since supernovae are both relatively rare, and impossible to predict with any accuracy, the existence of such before-and-after images is precious for astronomers who study these violent events.

NGC 5806, which is found about 80 million light years from Earth, is a relatively unremarkable galaxy. 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.

NGC 5806 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.