More M87

StarDate: May 14, 2009

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A project by Texas astronomer that's examining one of the most impressive galaxies around seems to have an unusual theme: darkness. The astronomers are studying the galaxy with an instrument that's designed to look for dark energy. One of the things they're considering is dark matter. And one of the goals is to "weigh" one of the greatest darknesses in the universe: a supermassive black hole.

The subject is M87, a galaxy that's about 60 million light-years away. It's many times larger and more massive than our own galaxy, the Milky Way.

A black hole sits in the center of the galaxy. Most estimates say it's about three billion times as massive as the Sun. Those estimates are based in part on the motions of stars around the galaxy's center.

But galaxies consist of more than just stars. In fact, most of their mass consists of dark matter -- matter that we can't see, but that exerts a gravitational pull on the visible matter around it.

Texas astronomer Karl Gebhardt recalculated the mass of the black hole by including the galaxy's dark matter. The results showed that the black hole is more than twice as massive as previously thought -- about seven billion times the mass of the Sun.

Now, Gebhardt and others are studying M87 with an instrument that's designed to look for dark energy. Its observations will provide a better look at how the stars of M87 move -- providing better measurements of M87's dark matter and dark heart.

Script by Damond Benningfield, Copyright 2009

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