Scientists examine the cutest little galaxy!

Segue 2 has 1,000 stars that try so hard to burn bright

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Image credit: Flickr/CJ ISHERWOOD


It's easy to feel overwhelmed by the vastness of space, but there actually is some scale out there; not everything is seemingly infinite.

For example, while the Milky Way -- the spiral galaxy that contains our solar system -- holds an estimated 100 billion to 400 billion stars, a tiny galaxy orbiting the Milky Way has a mere 1,000 stars. You could count them on a clear night with a good telescope (if you were in the galaxy, that is).

The dwarf galaxy, named Segue 2, was measured by a group of scientists that published findings Monday in The Astrophysical Journal.

Scientists have known about a number of dwarf galaxies orbiting the Milky Way for some time now, but data from Hawaii's Keck Observatory provide the clearest picture yet of these relatively tiny collections of stars.

In addition to estimating the number of stars in Segue 2, the scientific team from several universities was able to ballpark the luminosity of the dwarf galaxy at 900 L, or 900 times the brightness of our sun. The Milky Way, in comparison, is 20 billion times brighter.

It's the brightness of the Milky Way that makes it difficult for scientists to locate and study the many dwarf galaxies they believe are orbiting our own galaxy.

In their abstract, researchers call Segue 2 "the least massive galaxy known."

One other interesting thing: Segue 2 is held together by dark matter. Interesting, not unique, because dark matter comprises more than one-quarter (26.8%) of the mass/energy density in the universe. Dark energy comprises 69%, while "normal matter" -- stars and galaxies -- make up just 4.9%. I guess that makes us part of the dwarf matter. Great.

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