Motion of stars in ultradiffuse galaxy measured for first time
DOI: 10.1063/PT.5.029977
Nature : Since the discovery last year of 47 extremely dim galaxies in the Coma cluster, hundreds more have been observed there and elsewhere. Such ultradiffuse galaxies (UDGs) are thought to be as large as the Milky Way but emit much less light. Now Pieter van Dokkum of Yale University and Roberto Abraham of the University of Toronto in Canada and their colleagues have focused on one of the largest and brightest of the UDGs, called Dragonfly 44. From measurements of the galaxy’s spectral line, the researchers have been able to determine that Dragonfly 44’s stars are moving very quickly relative to one another, at some 47 km/s, which indicates the galaxy is massive, perhaps a trillion times as massive as the Sun. Despite what has been learned so far about UDGs, their origin remains a mystery.
