Monday, 27 January 2014

Supernova in M82

There is an unusually nearby supernova in the Galaxy M82. It's bright and easy to observe, and M82 is a brilliant target at this time of year.

 This supernova was first spotted at 19:20 on the 21st of January. The BRT's first image of the SN was taken (by chance) at 1:30am on the 22nd of January (6 hours later). Its brightness should peak at the end of January and still be visible for some time after that.

Type 1a Supernovae

 The supernova is thought to be a Type 1a supernova. These are unlike the Type II supernovae that I described briefly in my last post (in which a star explodes due to the collapse of its core at the end of its life). Rather, these supernovae originate in binary star systems, where two stars are in close orbit around each other.
 The more massive of the two stars will likely age fastest and may, like our Sun, end its life as a white dwarf. (White dwarves are the cores of stars left over after stars like our own Sun blow away their outer layers into space at the end of their lives). This does not generally disrupt the orbit of the two stars.
When the second star later expands to become a red giant towards the end of its life, its outer, hydrogen-rich layers may come within gravitational reach of the old white dwarf companion and be siphoned off onto it. If the second star is large enough, enough hydrogen may be accreted onto the first star for hydrogen fusion to reignite, which it does explosively, resulting in a Type 1a supernova.


 M82, also known as the Cigar Galaxy, is an edge-on spiral galaxy 11.5 million lightyears away. What this means of course is that the supernova we are seeing actually occurred 11.5 million years ago but the light is only just reaching us. It is visible to the BRT from October-June.


These pictures show a comparison between before and after the supernova occurred.

Hover to see the galaxy after the supernova

Taking your own images
  • You will want to use Galaxy Camera for this target
  • The image above was taken with BVR 180 000 ms - good for a colour picture
  • For a black & white image of the galaxy, use Clear 120 000 ms
  • If you want to collect photometric data about the supernova and don't really care about the host galaxy, 30 000 ms and a V filter should be fine.