ultrafaint dwarf galaxy tagged posts

The Milky Way is surrounded by dozens of dwarf galaxies that are thought to be relics of the very first galaxies in the universe. Among the most primitive of these galactic fossils is Tucana II—an ultrafaint dwarf galaxy that is about 50 kiloparsecs, or 163,000 light years, from Earth.

Now MIT astrophysicists have detected stars at the edge of Tucana II, in a configuration that is surprisingly far from its center but nevertheless caught up in the tiny galaxy’s gravitational pull. This is the first evidence that Tucana II hosts an extended dark matter halo—a region of gravitationally bound matter that the researchers calculated to be three to five times more massive than scientists had estimated...