Young stars discovered in dwarf spheroidal galaxies confirm their recent infall into the Milky way

TL;DR

Recent observations reveal young stars in dwarf spheroidal galaxies around the Milky Way, indicating recent infall and gas loss, which impacts understanding of their dynamics and dark matter content.

Contribution

This study provides observational evidence of recent infall of dwarf galaxies into the Milky Way, challenging previous assumptions about their gas content and evolution.

Findings

Detection of young stars in dwarf spheroidal galaxies

Recent infall of these galaxies into the Milky Way less than 3 Gyr ago

Implications for their dynamics and dark matter estimates

Abstract

Recent observations from the ESA Gaia satellite and with the ESO VLT, have identified the presence of a population of young, 0.5 to 2 Gyr old, stars in the halo and in dwarf spheroidal galaxies surrounding the Milky Way. It suggests that MW dwarf galaxies, currently devoid of gas, had, until recent times, enough gas to sustain a burst of star formation. The recent loss of gas coincides with their arrival in the vicinity of the Milky Way, in agreement with orbital predictions from Gaia that indicate that most dwarf galaxies reached the Milky Way halo less than 3 Gyr years ago. This completely changes the interpretation of their dynamics, mass, and dark matter content.