What is the relationship between stars in a cluster

Star clusters are groups of stars which are gravitationally bound. Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young.

The president wanted to have the party at her house.

The forms his, her, hers, their and theirs are possessive in nature.

"His and her" is used when referring to one person while "their" is used for multiple people. The house is singular.