Editing Sirius (section)

=== {{Anchor|Sirius supercluster}}Star cluster membership ===
In 1909, [[Ejnar Hertzsprung]] was the first to suggest that Sirius was a member of the [[Ursa Major Moving Group]], based on his observations of the system's movements across the sky. The Ursa Major Group is a set of 220&nbsp;stars that share a common motion through space. It was once a member of an [[open cluster]], but has since become gravitationally unbound from the cluster.<ref name="Frommert2003"/> Analyses in 2003 and 2005 found Sirius's membership in the group to be questionable: the Ursa Major Group has an estimated age of 500 ± 100&nbsp;million years, whereas Sirius, with metallicity similar to the Sun's, has an age that is only half this, making it too young to belong to the group.<ref name="Liebert2005"/><ref name="King2003"/><ref name="Croswell2005"/> Sirius may instead be a member of the proposed Sirius Supercluster, along with other scattered stars such as [[Beta Aurigae]], [[Alpha Coronae Borealis]], [[Beta Crateris]], [[Beta Eridani]] and [[Beta Serpentis]].<ref name="Eggen1992"/> This would be one of three large clusters located within {{convert|500|ly|pc}} of the Sun. The other two are the [[Hyades (star cluster)|Hyades]] and the [[Pleiades]], and each of these clusters consists of hundreds of stars.<ref name="Olano2001"/>