Gaia satellite spots dim, low-density galaxy hiding in the Milky Way's shadow
Massive amounts of data are generated by orbiting scientific platforms like the Hubble, and the ESA's Gaia satellite; so much data that it often takes years for researchers to pour through. An international team of astronomers were pouring through Gaia data recently and discovered a massive "ghost" galaxy hiding behind the shroud of the Milky Way's disc. The new galaxy has been named Antila 2 or Ant 2 and is said to be an extremely low-density galaxy.
Ant 2 is a dwarf galaxy, a type of structure that emerged in the early Universe and were among the first galaxies to form. This type of galaxy has mostly old, low-mass and metal-poor stars. One interesting fact about Ant 2 is that the galaxy is so massive compared to other dwarf galaxies.
Astronomers say that Ant 2 is about a third of the size of the Milky Way and is as big as the Large Magellanic Cloud. One reason this giant galaxy has stayed hidden so long is that it puts out little light; Ant 2 is 10,000 times fainter than the Large Magellanic Cloud. The team says that objects as diffuse as Ant 2 have never been seen before and the discovery was made because of the quality of data that Gaia collected. Gaia is on a mission to create the richest star catalog ever made with high precision measurements of almost 1.7 billion stars.
The team of researchers that discovered Ant 2 are from the US, UK, Taiwan, Australia, and Germany. The team tried to get more data on Ant 2 via the Anglo-Australian Telescope in Australia. The coordinates of Ant 2 gave a limited window of opportunity for observation before the movement of the Earth around the sun made it impossible to view Ant 2 for months to come.
The observations made were enough to confirm that Ant 2 is real and that it never comes closer to the Milky Way than 130,000 light-years. The team thinks that the reason Ant 2 has such a low mass is that the Galactic tides from the Milky Way are taking Ant 2 apart, but its massive size suggests that Ant 2 was born a giant.