Here’s a more recent photo, as of January 25. It’s going to get even brighter than that. Right now, it’s at about magnitude 10.5. In another week or so, it’s expected to hit magnitude 8.5, or in other words, as bright as the entire galaxy!
SN 2014J is a Type Ia supernova. This is not a case of an old, massive star exploding. The jury is still out on exactly how Type Ia’s happen, but we believe that they are caused by two dead stars–white dwarfs colliding and exploding. A Type Ia supernova is both rarer and brighter than the usual exploding stars, which are Type II.
M82 is about 12 million light-years away, which sounds like a lot, but this is actually the closest supernova of any type in a generation. The last one that was this close was SN 1993J, which went off in the neighboring galaxy M81. That was a Type II supernova, so this one should be even brighter–the brightest since SN 1987A in the Large Magellanic Cloud. And before that, you have to go all the way back to SN 1885 in the Andromeda Galaxy over a hundred years earlier to find anything even comparable. So this truly could be a once in a lifetime event.
So how do you find it? If you’re in the Northern Hemisphere, like me, you’re in luck, because this is a far northern object. And because it’s so close, it will be pretty easy to spot even with just binoculars. Go out in the late evening and look to the northeast. You should see something that looks like this:
In the yellow circle, near the familiar form of the Big Dipper, are the two nearby galaxies, M81 and M82. Take your binoculars to them, and they’ll look like little fuzzy patches, but one of those fuzzy patches will have a bright star in it–the supernova. In a long-exposure photograph, it will look something like this:
Here’s the other interesting thing about SN 2014J. M82 is a starburst galaxy–in other words, it’s forming lots and lots of new stars. Some of those star will be massive and will quickly explode…as Type II supernovae. We’d expect to see plenty of those in M82, but Type Ia’s come from old stars. We wouldn’t expect to see nearly as many of those there, so this one is an especially rare treat.