Discovery boosts efforts to understand dark matter
V. Belokurov and S. Koposov/IoA/Cambridge; Y. Beletsky/Carnegie Observatories
The Milky Way’s entourage of satellites just welcomed a few new members.
Two teams of astronomers independently discovered eight, or possibly nine, satellite galaxies around the Milky Way, adding to the 27 previously known. These galaxies, despite being tiny, hold clues about the formation of the Milky Way, the birth of the first galaxies, and the nature of dark matter, the elusive substance thought to hold galaxies together.
All the galaxies were found near the Large Magellanic Cloud, the largest Milky Way satellite. The nearest sits about 100,000 light-years away in the constellation Reticulum; the farthest, in the constellation Eridanus, is just over 1 million light-years from Earth — roughly half the distance to the Andromeda galaxy. The findings appear in four papers published online at arXiv.org on March 9.
Most of these satellites contain about a few thousand stars, far fewer than the Milky Way’s roughly 100 billion. But astronomers can see