A "Sternhaufen," or star cluster, is a group of stars that are physically close to each other in space. These clusters are bound together by gravity and can contain hundreds to thousands of stars. There are two main types of star clusters: open clusters, which are loosely packed and often contain younger stars, and globular clusters, which are densely packed and typically contain older stars. Star clusters are important for astronomers because they provide insights into the formation and evolution of stars. By studying a Sternhaufen, scientists can learn about the age, composition, and dynamics of stars, helping to improve our understanding of the Milky Way and the universe as a whole.