Milky Way has {at least} 3 more satellite galaxies (EarthSky.org)

[eppur_se_muova]

At least! Six other objects could be either dwarf galaxies or globular clusters. These humble Milky Way satellites are a key to the dark matter puzzle.

A team of astronomers from the University of Cambridge says it has identified nine new objects – three definite small galaxies and six either galaxies or globular clusters – orbiting our Milky Way galaxy. They say it’s the largest number of small objects orbiting the Milky Way ever discovered at once. Nine does sound like a lot, given that our Milky Way galaxy has only about 150 known globular clusters, and only a couple of dozen possible satellite galaxies, with the irregular Large and Small Magellanic Clouds – visible from Earth’s Southern Hemisphere – being the best known. These objects were found via newly-released imaging data taken from the Dark Energy Survey. The astronomers say these humble objects orbiting our Milky Way might help unravel the some of the mysteries behind dark matter. In a statement released on March 10, 2015, the University of Cambridge also said:

The new results also mark the first discovery of dwarf galaxies – small celestial objects that orbit larger galaxies – in a decade,* after dozens were found in 2005 and 2006 in the skies above the Northern Hemisphere.

The new satellites were found in the Southern Hemisphere near the Large and Small Magellanic Clouds …

Our Milky Way galaxy contains hundreds of billions of stars, but dwarf galaxies are known with as few as 5,000 stars. These astronomers say the newly discovered galaxies 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.

Dr. Sergey Koposov of Cambridge’s Institute of Astronomy, the study’s lead author, said:

The discovery of so many satellites in such a small area of the sky was completely unexpected. I could not believe my eyes.

In recent years, the couple of dozen Milky Way satellite galaxies have puzzled astronomers. The number of known dwarf galaxies orbiting our Milky Way is not as large as scientists believe it should be, based on computer simulations. The most accepted cosmological models of the universe predict there should be hundreds of dwarf galaxies in orbit around our Milky Way. But, so far, we haven’t seen hundreds.



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more: http://earthsky.org/space/milky-way-has-3-more-satellite-galaxies
http://www.cam.ac.uk/research/news/welcome-to-the-neighbourhood-new-dwarf-galaxies-discovered-in-orbit-around-the-milky-way

* Evidently, Cambridge astronomers don't read the International Business Times. Or DU.