Star clusters or Clouds of stars are groups of stars that are gravitatively and formally bonded to each other. There are two types of star clusters that are commonly found, namely:
The ball group is a group of hundreds or thousands of very old stars and is tightly bound to each other. Because of its relatively close interstellar distance, these clusters form like spheres where the star density is higher in the center. An example of a spherical cluster is a Messier group of 13.
Open groups are groups of stars that are tied more apart, typically consisting of no more than a hundred stars where members are often very young. This cluster will split over time because of the gravitational influence of molecular clouds in their movement orbiting the galaxy, An example of an open group is the Kartika cluster. 