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Weighing Black Holes

August 6, 2008

A new technique helps scientists measure the mass of giant black holes.


Sizing up black holes. I’m Bob Hirshon and this is Science Update.

A "black hole" isn’t really a hole, but collapsed matter so dense that not even light can escape its gravity. Now, University of California at Irvine X-ray astronomer Phillip Humphrey and his colleagues have developed a new way to weigh these massive objects. Humphrey says that has to be done indirectly, because nothing inside a black hole is visible.

PHILLIP HUMPHREY (University of California at Irvine):
It makes it a very difficult measurement to measure very accurately. // So what we do is we want to use as many different techniques as we can to look at an individual object.

His team calculated a nearby black hole’s mass from the temperature of gas in its vicinity: gas that’s compressed and heated by the black hole’s gravity. Their answer of 3.4 billion times the mass of the Sun confirmed prior estimates. I’m Bob Hirshon for AAAS, the Science Society.