Stars in Star Clusters Observed To Age At Varying Rates

Astronomers at the ESO, ESA, and NASA have observed that some stars in star clusters appear young looking than other stars. This is despite the fact that most of the stars in a cluster were formed at the same time and are roughly the same age. This observation was arrived at upon studying bright blue stars called blue stragglers which appear younger than other stars in the cluster.

Star clusters, as the name suggests, are groups of stars that are grouped together. These stars are bound together by their respective gravitational fields.

There are two kinds of clusters; open star clusters and globular star clusters. Open star clusters are a loosely group of hundreds of young stars. Their gravitational attraction is not strong enough to form a tight bond.

A globular star cluster is made up of hundreds and thousands of very old stars whose gravitational attraction to each other is strong enough that they form a very tight spherical shape. As one goes closer to the center, the number of stars get denser.

These clusters orbit a galaxy or the galactic core as one unit much like a satellite would.

The Milky Way galaxy is known to host around 150 star clusters but many more are believed to be undiscovered. The closest galaxy to the Milky Way, the Andromeda galaxy, has 500 clusters while Galaxy M87 has 13,000 globular clusters.

The image above shows the globular cluster NGC 6388 observed by the European Southern Observatory.