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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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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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