Of the globular clusters within the Milky Way, the majority are found in a halo around the galactic core, and the large majority are located in the celestial sky centered on the core.

Globular clusters are old clusters of stars that have remained in a gravitationally bound system. Open clusters are much younger and smaller than globular clusters. They are the recent birthplaces of new stars, which form out of clouds of dust and gas, and contain only hundreds or thousands of stars.

150 globular clusters

Omega Centauri

Globular star clusters are known to be located mostly in the great spherical halo of the Milky Way. Spiral galaxies like our Milky Way contain stars, gas and dust, mostly organized into a flat disk containing the spiral arms, but with the addition of a more rounded bulge and halo, centered on the galaxy’s center.

It has several hundred thousand stars. A globular cluster is a group of stars of a similar age which often orbits the central bulge of a galaxy. Gravity holds clusters together and gives them their spherical shape. Towards the centre of a clusters there are many stars in a relatively small space.

To live on an Earth in a globular cluster would mean that the cluster’s stars (if they were like our Sun) would combine to create a night sky at around 20 times brighter than Earth’s night sky at full Moon.

disk of the Galaxy

cluster Omega Centauri

Omega Centauri is also the brightest globular cluster, at apparent visual magnitude 3.9 it is visible to southern observers with the unaided eye.

Globular clusters are incredibly dense structures often featuring hundreds of thousands of stars packed into a relatively small space. This cluster packs 570,000 stars in an expanse of space that’s a “mere” 120 light-years across.

One of the densest globular clusters in the Milky Way, M80 is located roughly 28,000 light-years from Earth and holds hundreds of thousands of stars. What keeps these clusters from collapsing is the angular momentum of the stars as they orbit the cluster’s center of mass.

Physics. Globular clusters formed from giant molecular clouds, or huge masses of gas that form stars as they collapse. Because there is less free gas available now than at the beginning of the universe, globular clusters generally cannot form today.

Globular clusters (GCs) are spheroidal collections of 100,000 to a million stars found orbiting in the halos of all large galaxies. Some GCs have been shown to be almost as old as the age of the Universe, making them among the oldest stellar populations known.

Elliptical galaxies

Virgo Cluster

Star cluster, 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. The two types are open (formerly called galactic) clusters and globular clusters.

Stars in an open cluster have a common origin – they formed from the same initial giant molecular cloud. Clusters typically contain a few hundred stars though this can vary from as low as a few dozen up to a few thousand.

The three basic types of clusters astronomers have discovered are globular clusters, open clusters, and stellar associations.

Advantages in studying stars clusters. we can easily find the main sequence and figure the distance. Also, if a cluster is close enough, we can measure proper motions. The proper motions will converge toward a point in the sky, which indicates the direction of travel for the cluster.

By determining the mass of the main-sequence turnoff stars, we get the age of the cluster. The cluster age equals the main-sequence lifetime of the turnoff stars. This is one of the ways we have studied the age of the Universe and the formation history of the Galaxy.

Star Clusters. When stars are born they develop from large clouds of molecular gas. This means that they form in groups or clusters, since molecular clouds are composed of hundreds of solar masses of material. After the remnant gas is heated and blow away, the stars collect together by gravity.

Eventual fate These clusters will rapidly disperse within a few million years. In many cases, the stripping away of the gas from which the cluster formed by the radiation pressure of the hot young stars reduces the cluster mass enough to allow rapid dispersal.

It is often stated that star clusters are the fundamental units of star formation and that most (if not all) stars form in dense stellar clusters.

Star clusters: Star clusters are groups of stars, from a few dozen to a few million, that are loosely held together by gravity. Galaxies: Galaxies are huge collections of solar systems and star clusters, often containing billions of stars. Galaxies are held together by gravity.