An overmassive Dark Halo around an Ultra-diffuse Galaxy in the Virgo Cluster

Ultra diffuse galaxies (UDGs) have the sizes of giant galaxies but the luminosities of dwarfs. A key to understanding their origins comes from their total masses, but their low surface brightnesses (\mu(V) \geq 25.0) generally prohibit dynamical studies. Here we report the first such measurements for a UDG (VCC~1287 in... Show more