Minuscule motions of stars in Sculptor dwarf galaxy
This visualisation shows the minuscule shifts in the positions observed on the plane of the sky – called proper motions – of about a hundred stars in the Sculptor dwarf galaxy, a satellite of our Milky Way.
To measure these proper motions and study how stars move in this galaxy, a team of astronomers have combined two different data sets collected twelve years apart: observations performed with the NASA/ESA Hubble Space Telescope in 2002, and the first set of publicly released Gaia data, gathered between 2014 and 2015.
To make them visible, the stellar motions have been exaggerated in this view, which shows an estimate of the shift in the star positions that would be observed after 100 000 years instead of twelve.
This study has allowed the astronomers to pin down for the first time the three-dimensional motions of individual stars in the Sculptor dwarf galaxy, shedding new light on the underlying distribution of invisible dark matter that pervades the galaxy.