Two images of the supernova detected early this morning in M82, the Cigar Galaxy. The bright circle near the image center is the supernova, which you can see more clearly in the negative-color version at the right. [Credit: Ernest Guido, Nick Howes, Martino Nicolini]
Pardon me, I’m a little excited. When I logged onto my computer this morning, I found that every astronomer and astronomy fan was talking about the same thing: a new observation of a probable white dwarf supernova
in M82, also known as the Cigar Galaxy. This is exciting because M82 is practically a neighbor in cosmic terms, a mere 12 million light-years distant. That makes this supernova the closest of its kind in decades (though I’m still trying to sort out which was closer, and when it happened). Suffice to say, the galaxy is close enough that the supernova is sufficiently bright to be visible with relatively small telescopes, and will continue to get brighter over the next few weeks. It’s projected to reach a magnitude of +8, which is bright enough to be seen with binoculars!
Type Ia supernovae are triggered either by the explosion of white dwarfs that accrete too much matter and exceed their maximum stable mass, or by the collision of two white dwarfs. (That’s as opposed to core-collapse supernovae, which are the explosions of stars much more massive than the Sun.) Because they all explode in very similar ways, Type Ia supernovas are “standard candles”: objects that can be used to measure distances to very distant galaxies. The use of them to track the expansion of the Universe was recognized by the 2011 Nobel Prize. [read more…]
What’s cool is that various astronomers, including a number of amateur astronomers, spotted the supernova before it was identified as such. M82 is a popular observing target because it’s distinctive and (yes) not far away. My colleagues at Universe Today and CosmoQuest actually highlighted the galaxy during their Virtual Star Party on Sunday evening, meaning they saw the supernova before we knew what a big deal it was going to be!