Messier 30 – The Jellyfish Cluster

Generally found in globular clusters, blue stragglers are stars that appear brighter and bluer than we would expect given the cluster’s age. Scientists are not sure what causes this, but one prominent theory suggests they are the result of star collisions in a densely packed cluster or they form when one star siphons mass from another nearby star. Scientists have evidence to suggest that both kinds of blue stragglers are part of Messier 30 (M30) in the Capricornus constellation.

Globular clusters are ancient collections of stars that are gravitationally bound together in a spheroidal shape. Some are almost as old as the universe itself. They can contain anywhere from tens of thousands of stars to millions of stars. The stars they house tend to be very old as well, because star formation inside the cluster has largely ceased. The formation of globular clusters is not well understood. Current research leans toward the idea that they formed from very dense molecular clouds in the early universe. Some larger globular clusters may once have been dwarf galaxies whose larger star populations were stripped away from the core by larger galaxies.

M30 has undergone a process called core collapse. This phenomenon occurs when so many stars are packed in such a small space that they start attracting each other gravitationally toward the center of the cluster. Of the 157 globular clusters known to orbit the Milky Way, 21 of them have undergone a core collapse. Having so many stars so close together (it’s core spans less than a light year) may help explain why these blue stragglers are there.

M30 Facts

Distance: 27,100 light years

Number of stars: 150,000

Diameter: 139 light years

Age: 12.9 billion years