These two stars make up the second star in the handle of the Big Dipper. Some change brightness because of mutual eclipses of double stars. Others are stars, which actually change in size and temperature. These stars are thought to be near the end of their life cycle and vary in brightness because their fuel is nearly exhausted. Instead, they form in groups, associations, and clusters.
Gravity is the deciding factor for all clusters.
If the gravitational force is weak, the stars drift apart forming an open cluster. There are two types of clusters, open clusters that are thought to be relatively young on the cosmic time scale, and globular clusters, which are thought to be the oldest stars in the galaxy. All the stars, clusters, and nebulae seen with the unaided eye are part of the Milky Way Galaxy. The Milky Way is just one of millions or perhaps billions of galaxies in the universe. The locations of many of these galaxies have been known for decades.