20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

Gaia EDR3 proper motions of Milky Way dwarfs

20 Mar 2023, 11:30
Haus H, Telegrafenberg

Haus H, Telegrafenberg

Potsdam, Germany
Contributed talk SESSION 1: From ground and space: motions, distances, chemistry and star formation measurements SESSION 1: From ground and space: motions, distances, chemistry and star formation measurements


Hefan Li (National Astronomical Observatories)


Based on Gaia Early Data Release 3 (EDR3), we estimate the proper motions for 46 dwarf galaxies of the Milky Way. The uncertainties in proper motions, determined by combining both statistical and systematic errors, are smaller by a factor 2.5, when compared with Gaia Data Release 2. We have derived orbits in four Milky Way potential models that are consistent with the MW rotation curve. Although the type of orbit (ellipse or hyperbola) are very dependent on the potential model, the pericenter values are firmly determined, largely independent of the adopted MW mass model. By analyzing the orbital phases, we found that the dwarf galaxies are highly concentrated close to their pericenter, rather than to their apocenter as expected from Kepler's law. This may challenge the fact that most dwarf galaxies are Milky Way satellites, or alternatively indicates an unexpected large number of undiscovered dwarf galaxies lying very close to their apocenters. Between half and two thirds of the satellites have orbital poles that indicate them to orbit along the Vast Polar Structure (VPOS), with the vast majority of these co-orbiting in a common direction also shared by the Magellanic Clouds, which is indicative of a real structure of dwarf galaxies.

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Primary authors

Hefan Li (National Astronomical Observatories) Francois Hammer Dr Carine Babusiaux (Paris Observatory) Dr Marcel S. Pawlowski (Leibniz-Institut fur Astrophysik Potsdam (AIP)) Yanbin YANG (CNRS France / Paris Observatory) Frederic Arenou Cuihua Du Jianling WANG

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