Saturday, April 5, 2014

ScienceDaily: Astronomy News

ScienceDaily: Astronomy News


Watching for a black hole to gobble up a gas cloud: Gas cloud's fate illuminates growth of supermassive black holes

Posted: 04 Apr 2014 05:58 AM PDT

G2, a doomed gas cloud, is edging closer to Sgr A*, the hungry supermassive black hole at the Milky Way's center. The closest approach between the two is predicted to occur any day now. Astrophysicists have been watching closely, and the data do not show enhanced emission in the X-rays.

Gravity measurements confirm subsurface ocean on Saturn's moon Enceladus

Posted: 03 Apr 2014 11:20 AM PDT

In 2005, NASA's Cassini spacecraft sent pictures back to Earth depicting an icy Saturnian moon spewing water vapor and ice from fractures, known as "tiger stripes," in its frozen surface. It was big news that tiny Enceladus -- a mere 500 kilometers in diameter -- was such an active place. Since then, scientists have hypothesized that a large reservoir of water lies beneath that icy surface, possibly fueling the plumes. Now, using gravity measurements collected by Cassini, scientists have confirmed that Enceladus does in fact harbor a large subsurface ocean near its south pole, beneath those tiger stripes.

Monster 'El Gordo' galaxy cluster is bigger than thought

Posted: 03 Apr 2014 11:18 AM PDT

Astronomers have weighed the largest known galaxy cluster in the distant universe and found that it definitely lives up to its nickname: El Gordo (Spanish for "the fat one"). By precisely measuring how much the gravity from the cluster's mass warps images of far-more-distant background galaxies, a team of astronomers has calculated the cluster's mass to be as much as 3 million billion times the mass of our Sun. The Hubble data show that the cluster is roughly 43 percent more massive than earlier estimates based on X-ray and dynamical studies of the unusual cluster.

Fermi data tantalize with new clues to dark matter: Gamma rays from center of Milky Way galaxy

Posted: 03 Apr 2014 09:36 AM PDT

A new study of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe. Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

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