Out of the Blue | by Brian Koberlein



13 June 2014

A Hubble WFPC2 image of the core of M31.
A Hubble WFPC2 picture of the core of M31.

The picture above is of the very heart of the Andromeda galaxy. When you look in the midst of this picture, you’ll see a smudge of blue. As first demonstrated in an article in Astrophysical Journal, the central blue area is a group of about 400 younger blue stars. They’re concentrated in a area a couple of gentle yr throughout, and are transferring at about 1,000 km/s.

Artist rendering of Andromeda's core.
NASA, ESA, and A. Feild (STScI)
Artist rendering of Andromeda’s core.

We all know these stars are so densely packed and transferring so rapidly as a result of they’re orbiting Andromeda’s supermassive black gap. However what’s notably attention-grabbing about these stars is that they’ve quick lifetimes on a cosmic scale, so it’s unlikely that simply occurred to look round Andromeda’s core. What’s extra possible is that they fashioned close to the core, and that Andromeda’s core undergoes cycles of stellar formation to provide this sort of blue cluster.

It’s an attention-grabbing perception into the area close to a supermassive black gap, and one we don’t totally perceive. What would drive this sort of cyclic star formation within the area? Maybe the reply will seem someday out of the blue.

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