My God. It’s full of stars.

This beautiful little image is of the Arches Star Cluster. Taken recently, using the VLT (Very Large Telescope), it’s the sharpest image ever taken of this ellusive group of stars.

You see, the Arches Cluster isn’t easy to see from Earth. It lies roughly 100 light years from the core of the Milky Way, which is really incredibly close. The trouble with anything that close to our old friend Sagittarius A* is that, well, there’s a couple of galactic spiral arms worth of dust and stars in the way. The dust is the troublesome part, obscuring and scattering light (a process astronomers refer to as “extinction”).

One quite remarkable thing about the Arches Cluster is that it’s actually the densest known cluster of young stars in the Galaxy! With over a thousand stars per cubic light year (it’s only around three light years in diameter), it makes the term “open cluster” seem slightly ironic. Very roughly, that’s one star every 6000 AU! I think it’s safe to say that if you lived on a planet there, you might not need street lights. Assuming you could live in an ultraviolet flux that potent. These are massive stars we’re talking about. They’re going to be putting out a considerable amount of UV.

It’s also just a baby, at a mere 4 million years old. As such, it’s full of short lived but extremely massive stars, with up to 130 solar masses. Stars with this much mass live fast and die young. In other words, fairly soon (at least on astronomical timescales), a lot of them will probably start bursting as supernovae.

Perhaps the most interesting thing though, about this little stellar garden, is where it is. They’re in close proximity to a supermassive black hole, and yet they seem to form in much the same way as they would anywhere else. To quote Steward Observatory’s Pablo Espinoza (first author on a recent paper);

“With the extreme conditions in the Arches Cluster, one might indeed imagine that stars won’t form in the same way as in our quiet solar neighbourhood. However, our new observations showed that the masses of stars in this cluster actually do follow the same universal law.”

It seems, star formation is quite a hardy process. You have to wonder if planet formation is similarly resilient. Seemingly, this all ties in fairly well with my recent post about hypervelocity stars. Maybe A*’s gravity will one day scatter the Arches Cluster and send a couple of them hurtling out of the galaxy. Time will tell…

EDIT– For more info, have a glance at the ESO press release!

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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  1. Pingback: The centre of the galaxy | Supernova Condensate

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