Re: Yahoo! News Story - US astronomers spot massive, record-setting stellar-mass
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> US astronomers spot massive, record-setting stellar-mass black hole
zodiacal coordinates, yet. I'll try to get that up soon.
Mark A. Holmes
US astronomers spot massive, record-setting stellar-mass black hole
Wed Oct 31, 4:14 PM ET
WASHINGTON (AFP) - US astronomers have discovered the biggest black
hole orbiting a star 1.8 million light-years from Earth in the
constellation Cassiopeia, with a record-setting mass of 24 to 33 times
that of our Sun, NASA said Tuesday.
The massive newcomer beats the previous stellar-mass black hole
discovered October 17 in the M33 galaxy that has 16 times the mass of
our Sun, the US space agency said.
Like the much larger, supermassive black holes found at galaxy
centers, stellar-mass black holes have such powerful gravity fields
that not even light can escape them. Astronomers estimate their mass
by measuring their gas emissions and the gravitational effect on the
stars they orbit.
"We weren't expecting to find a stellar-mass black hole this massive,"
says Andrea Prestwich of the Harvard-Smithsonian Center for
Astrophysics in Cambridge, Massachusetts.
Lead author of the discovery paper in the November 1 Astrophysical
Journal Letters, Prestwich and his team found the new stellar-mass
black hole using NASA's Chandra X-ray Observatory.
"We now know that black holes that form from dying stars can be much
larger than we had realized," he added.
Prestwich's team was able to measure the black hole's mass because it
has an orbiting companion: a hot, highly evolved star. The star is
ejecting gas in the form of a wind.
Some of this material spirals toward the black hole, heats up, and
gives off powerful X-rays before crossing the point of no return.