Scientists Discover Multiple Dwarf Galaxies Orbiting Our Own

March 10, 2015 | Prachi Gupta

Astronomers are hyped after finding that there may up to nine dwarf galaxies orbiting the Milky Way Galaxy. A dwarf galaxy, the smallest type of galaxy, is a cluster of at least 5,000 stars. Though scientists predict that there are a lot of dwarf galaxies around our own massive galaxy, they are notoriously hard to spot because of their size. But the findings, released by researchers at the University of Cambridge and the Dark Energy Survey, reveal the first dwarf galaxy spotting in nearly a decade.

From Science Daily:

The newly discovered objects are a billion times dimmer than the Milky Way, and a million times less massive. The closest is about 95,000 light years away, while the most distant is more than a million light years away.

According to the Cambridge team, three of the discovered objects are definite dwarf galaxies, while others could be either dwarf galaxies or globular clusters — objects with similar visible properties to dwarf galaxies, but not held together with dark matter.

“The discovery of so many satellites in such a small area of the sky was completely unexpected,” said Dr Sergey Koposov of Cambridge’s Institute of Astronomy, the study’s lead author. “I could not believe my eyes.”

Scientists hope to learn more about dark matter, the material thought to exist between weakly associated particles:

“Dwarf satellites are the final frontier for testing our theories of dark matter,” said Dr Vasily Belokurov of the Institute of Astronomy, one of the study’s co-authors. “We need to find them to determine whether our cosmological picture makes sense. Finding such a large group of satellites near the Magellanic Clouds was surprising, though, as earlier surveys of the southern sky found very little, so we were not expecting to stumble on such treasure.”

(Image: Y. Beletsky/Carnegie Observatories)