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The Pyrenean ibex, an impressive mountain goat that lived in the central Pyrenees in Spain, went extinct in 2000. But a...
Tight budgets are forcing NASA to consider turning off one or more planetary science projects that have completed their...
Ebola is not a stranger to West Africa—an outbreak in the 1990s killed chimpanzees and sickened one researcher. But the...
In an as-yet-unpublished report, an international panel of geoscientists has concluded that a pair of deadly...
Tropical disease experts tried and failed before to eradicate yaws, a rare disfiguring disease of poor countries. Now,...
Since 2002, researchers have reported that agricultural communities in the hot and humid Pacific Coast of Central...
Balkan endemic kidney disease surfaced in the 1950s and for decades defied attempts to finger the cause. It occurred...
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ScienceShot: Weighing Distant Black Holes
30 January 2013 1:10 pm
Give astronomers a few hours, and they can tell you the mass of any black hole within 244 million light-years. That's possible with a new technique that involves measuring the impacts of the light-sucking objects on clouds of molecular gas circling the centers of their home galaxies. In a paper published online today in Nature, researchers report that they have used the method to weigh the supermassive black hole at the heart of NGC 4526, which lies 53 million light-years away. Previously, researchers have estimated black hole masses by modeling their gravitational effects on individual stars or on clouds of electrically charged gases, but the motions of those objects are typically much more random than the motions of clouds containing uncharged gases. In the new work, scientists training their radio telescopes on NGC 4526 specifically measured the motions of gas clouds (depicted in purple, and superimposed on a Hubble Space Telescope image) containing carbon monoxide, a gas commonly found in such clouds. The motions of those clouds, as observed at a particular wavelength of microwave radiation, indicate that the black hole that resides there is about 450 million times the mass of our sun. Using the new technique with radio-telescope arrays poised to come on line soon, scientists should—working at the same resolution and sensitivity of today's instruments—be able to readily estimate in a matter of hours the masses of black holes inhabiting the centers of galaxies up to 244 million light-years away from ours. That's a volume of space that contains tens of thousands of galaxies, including hundreds that host substantial clouds of molecular gas, the researchers note.
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