A star cluster or a constellation can be a name given to a close knit grouping of stars. A group of constellations will form a galaxy..
Globular ClusterA huge group of stars that are close together is a star cluster. With many more stars it is a galaxy.
constelltions
A "cluster".
Constellation
A small group of stars that appear to be close together are often known a cluster. Technically its an asterism.
Globular ClusterA huge group of stars that are close together is a star cluster. With many more stars it is a galaxy.
They are called "Star Clusters".
A constellation is a group of stars that appear to be together in a group, but are not actually close to each other. They appear to be together because they are along the same general line from Earth to those stars. Also the constellations can change over time due to the position of the Earth. One star can have a surface temperature, but a group of stars does not have a common surface, or even an average temperature for the group.
no stars are not close together in a contellestion
The units currently used for distance between stars are either light-years, or parsecs. If the stars are very close together (as in a binary system), AU might also be used.
A galaxy
Yes