A team of astronomers used Hubble to study the blue straggler star
content in Messier 30, which formed 13 billion years ago and was discovered in 1764 by Charles Messier.
To better understand cluster ageing, the team mapped the location of blue straggler stars
in 21 globular clusters, as seen in images from Hubble and the MPG/ESO 2.2-metre telescope at the ESO La Silla Observatory, among other observatories.
Blue Straggler Stars
"A puzzling feature of many globular clusters is the presence in them of an appreciable number of fairly hot stars, in apparent defiance of the modern theory of stellar evolution....