Messier Monday: A Titan in a Teapot, M69
"Messier 69 is so old that all the O, B, A, and even F-class stars have run through their entire life cycles. Even the brightest and bluest G-stars have died; the most massive main-sequence stars left in Messier 69 are G2-stars, the same class as our humdrum Sun. That places the age of this cluster at around 13.1 billion years, meaning that the stars in here formed when the Universe was only 700 million years old!
This isn’t that strange; globular clusters are often among the oldest objects known in the Universe, and even the Messier catalogue contains some that are older than this one. But when we look at the elements present inside, that’s where Messier 69 starts to look funny."
When a star cluster has a color/magnitude diagram that says it's very old but a heavy element abundance that says it's relatively young, who wins? We all do, by learning more about how, when and where atomic riches accumulate in galaxies!