Messier 10

The stars in a binary system can be quite intimate. One star can pull gas off the surface of its companion, for example. And in extreme cases, the stars can merge to form a single star. Both types of interactions can make the stars look a lot younger than they really are. Many examples of this are found in Messier 10. It’s a globular cluster – hundreds of thousands of stars all packed into a ball a few dozen light-years across. The cluster includes an especially large number of blue stragglers – stars that look a lot younger and bluer than the cluster should contain. M10 itself is billions of years older than the Sun. It probably was born with many hot, blue stars. But such stars burn out quickly. So there’s no way that any of the cluster’s original blue stars could still be around. Instead, the blue stragglers probably were rejuvenated. Some appear to have stolen gas from a companion. The extra material “revs up” the nuclear reactions in the recipient, making it look much younger. Other blue stragglers may be the results of mergers – the stars spiral together. That would increase the rate of nuclear reactions as well – turning two old stars into what looks like a brand new one. Messier 10 is in Ophiuchus, the serpent bearer. The cluster is in the southwest as night falls, to the upper right of the teapot of Sagittarius. Through binoculars, the cluster looks like a hazy smudge of light. Script by Damond Benningfield