Saw this today and I find it pretty amazing that this galaxy was able to escape detection for so long due to it's low luminosity. Makes you wonder what else can be out there.
The scientists' abstract:
About four dozen known galaxies orbit our own. The largest in terms of breadth is the Sagittarius dwarf, discovered in 1994 but its big only because our galaxys gravity is ripping it apart. The next two largest are the Magellanic Clouds.
Now, Gabriel Torrealba at the University of Cambridge and his colleagues have found a new galaxy about 380,000 light years away in the constellation Crater. Its the fourth largest satellite of the Milky Way, Torrealba says.
Named the Crater 2 dwarf, the new galaxy is not apparent to human eyes, though individual stars within the galaxy are visible. The team were only able to find it this January by using a computer to look for over-densities of stars in data from images taken by a telescope in Chile.
Source: https://www.newscientist.com/articl...e-seen-galaxy-spotted-orbiting-the-milky-way/The galaxy eluded detection for so long because its stars are spread out from one another, giving it a ghostly appearance.
The scientists' abstract:
Source: http://arxiv.org/abs/1601.07178v3We announce the discovery of the Crater 2 dwarf galaxy, identified in imaging data of the VST ATLAS survey. Given its half-light radius of ∼1100 pc, Crater 2 is the fourth largest satellite of the Milky Way, surpassed only by the LMC, SMC and the Sgr dwarf. With a total luminosity of MV ≈ −8, this galaxy is also one of the lowest surface brightness dwarfs. Falling under the nominal detection boundary of 30 mag arcsec−2, it compares in nebulosity to the recently discovered Tuc 2 and Tuc IV and UMa II. Crater 2 is located ∼120 kpc from the Sun and appears to be aligned in 3-D with the enigmatic globular cluster Crater, the pair of ultra-faint dwarfs Leo IV and Leo V and the classical dwarf Leo II. We argue that such arrangement is probably not accidental and, in fact, can be viewed as the evidence for the accretion of the Crater-Leo group