The Milky Way's neighborhood is a bit more crowded than we thought.
Using data from NASA's Hubble Space Telescope, a Russian-American team of astronomers has discovered an isolated dwarf galaxy about 7 million light-years away from our galaxy.
Dubbed KKs3, the "dwarf spheroidal" galaxy is located in the southern sky in the direction of the constellation Hydrus. It's the most recently discovered member of the so-called Local Group of galaxies, which includes the Milky Way as well as the Andromeda Galaxy and dozens of other galaxies.
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A negative image of KKs 3 taken by the Hubble Space Telescope. The core of the galaxy is the right-hand dark object at top center, with its stars spreading out around it. (The left-hand of the two dark objects is a nearer globular star cluster.)
As galaxies go, KKs3 is pretty small. It's total mass is about one ten-thousandth the mass of the Milky Way, according to the astronomers. And it's only the second isolated dwarf spheroidal galaxy ever observed in the Local Group. (The first, known as KKR25, was discovered by the same astronomers in 1999.)
"Finding objects like KKs3 is painstaking work, even with observatories like the Hubble Space Telescope," Prof. Dimitry Makarov, of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia, and one of the members of the team, said in a written statement. "But with persistence, we're slowly building up a map of our local neighborhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there, something that would have profound consequences for our ideas about the evolution of the cosmos."
The discovery was described in Monthly Notices of The Royal Astronomical Society.