Very Old Dwarf Galaxy Discovered With Hubble Telescope

Posted on December 28, 2014

KKs3 galaxy

A very old dwarf galaxy has been discovered using the Advanced Camera for Surveys on the Hubble Space Telescope. The galaxy is named KKs3. It is located over 7 million light years from Earth.

NPR reports that this location puts KKs3 about 2.5 times farther away from Earth than Andromeda, our nearest large galaxy. KKs3 has just 1/10,000 the stellar mass of the Milky Way. Most of the stars in the galaxy (74%) were formed 12 gigayears ago. The dwarf spheroidal (dSPh) galaxy lacks features like the spiral arms found on galaxies like the Milky Way.

The astronomers say the dwarf galaxy is considered isolated because it is 2 megaparsecs (Mpc) from the nearest large galaxy and 1 Mpc from any known dwarf. The astronomers also say KKs3 has exhausted its star-forming fuel.

The team of astronomers was lead by Professor Igor Karachentsev of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia. Another team member, Professor Dimitry Makarov, from the Special Astrophysical Observatory, explained how difficult it is to find small galaxies like KKs3 in a Royal Astronomical Society release.

Makarov says, "Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope. But with persistence, we're slowly building up a map of our local neighbourhood, 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."

A research paper on the new galaxy can be found here in the journal, Monthly Notices Letters of the Royal Astronomical Society.

Photo: D. Makarov/Royal Astronomical Society