After bright explosion, astronomers rush to study new supernova

The bright circle at image center is a probable white dwarf supernova in M82 ("Cigar Galaxy"); the color-reversed inset shows the location more clearly.

Ernest Guido, Nick Howes, Martino Nicolini

Overnight, astronomers spotted what may be a very close white dwarf supernova—close in cosmic terms at least. This bright explosion, seen in the M82 "Cigar" galaxy, is roughly 12 million light-years away—close enough to be seen with small telescopes and observed in detail by larger instruments. Even amateur astronomers and astrophotographers can see an explosion this bright and close.

By 08:47 UT (3:47am US EST) on January 22, 2014, astronomers working with the ARC 3.5-meter telescope at the Apache Point Observatory reported they had measured the spectrum of the supernova. Based on that data, they identified it as a probable type Ia supernova, meaning it has little hydrogen, but significant amounts of silicon and other heavier elements.

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.