Looking Up: To Catch A Globular Cluster...

Oct 9, 2017

M 30, a glob of stars!
Credit NASA/STScI/WikiSky

This week on Looking Up we're back in the Constellation Capricornus, this time to hear about M 30, a globular cluster, and what makes it so special.

Have you ever felt like things were getting crowded? If so, you may have something in common with the remarkable globular cluster, known as Messier object number 30, high in the southern Colorado sky right now. 

Located in the constellation Capricornus, this cluster of about 200,000 stars is a wonder to behold. With stars around 13 billion years old, it’s almost as old as the universe itself. But what makes M 30 so special is that it is very crowded at its core. It seems this cluster has undergone what astronomers call a “core collapse” wherein lots of stars are pulled tightly toward the center of the cluster. It appears that the core is less than one light year across, with perhaps thousands and thousands of stars all crammed in there. Remember that the closest star to our own Sun is over 4 ly away. Imagine a night sky filled with super bright stars, all less than 1 ly away. Any astronomers in there must be very busy. 

But here is where it gets really weird. The orbit that M 30 follows around the core of our own Milky Way galaxy suggests strongly that M 30 didn’t form along with the Milky Way, but rather was stolen from another near-by galaxy by the Milky Way’s gravity. So if you see an astronomer looking at M 30 and yelling “thief, thief” at the sky, you’ll understand what’s going on.

If you’d like to take a closer look at M 30 or any of the wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.