Gaia spots ghost of a galaxy
Our new neighbour, Ant 2, is a third the size of the Milky Way
Our Galaxy has a vast ghostly neighbour hidden from view, astronomers have discovered. It’s a third the size of the Milky Way, but too dim to be seen through it.
An international team, including researchers from the University of Cambridge, identified the galaxy using data from ESA’s Gaia mission. It has been named Antlia 2, or Ant 2 for short.
It’s a dwarf galaxy, the first type to form in the Universe, which astronomers found by checking for RR Lyrae variable stars and finding several moving through the sky together. 130,000 lightyears distant, it is bigger than the Large Magellanic Cloud, but 10,000 times fainter. Scientists believe it lost mass due to the tidal pull of the Milky Way but are puzzled by its size.
“This is a ghost of a galaxy,” says Gabriel Torrealba, from Taiwan’s Academia Sinica in Taipei. “Objects as diffuse as Ant 2 have simply not been seen before.”