Star Clusters : Recently Discovered
Astronomers recently discovered five young star clusters, and possibly the oldest star clusters ever, born from the time when the Universe was an infant.
- A Star cluster is either of two general types of stellar assemblages held together by the mutual gravitational attraction of its members, which are physically related through common origin.
- They are particularly useful to astronomers as they provide a way to study and model stellar evolution and ages.
- The two basic categories of stellar clusters are open clusters, also known as galactic clusters and globular clusters.
- Open clusters are so named due to the fact that the individual component stars are easily resolved through a telescope.
- They are sometimes called galactic clusters due to their location on the dusty spiral arms on the plane of spiral galaxies.
- Stars in an open cluster have a common origin: they formed from the same initial giant molecular cloud.
- Open clusters contain from a dozen to many hundreds of stars, usually in an unsymmetrical arrangement.
- Globular clusters contain several thousand to one million stars in a spherical, gravitationally-bound system.
- Located mostly in the halo surrounding the galactic plane, they comprise the oldest stars in the galaxy.
- There is little free dust or gas found in globular clusters, so no new star formation is taking place in them.
- Stellar densities within the inner regions of a globular cluster are very high compared with regions such as those around the Sun.
