It turns out there are things in Lyra other than the Ring Nebula (Messier 57). This is NGC 6791. It’s an open cluster though when I first saw it I thought it might have been a fairly loose globular cluster, but the references say it’s an open cluster. But, it’s an unusual open cluster.

Its age is estimated at 8 billion years which seems quite a long time for an open cluster to hang together. What is also unusual is those oldest stars have an iron to hydrogen ratio that is more than twice that of our sun. That’s very odd for stars that old.

The cluster is a bit over 13,000 light years away.

For the technical details, see astrobin.