Archive for October 4, 2012

Comet Crystals Found In A Nearby Planetary System

October 4, 2012 Leave a comment

Olivine crystals. Credits: J. Debosscher, KU Leuven

Pristine material that matches comets in our own Solar System have been found in a dust belt around the young star Beta Pictoris by ESA’s Herschel space observatory.

Thanks to the unique observing capabilities of Herschel, the composition of the dust in the cold outskirts of the Beta Pictoris system has been determined for the first time.

Of particular interest was the mineral olivine, which crystallises out of the protoplanetary disc material close to newborn stars and is eventually incorporated into asteroids, comets and planets.

“Thanks to Herschel, we were able to measure the properties of pristine material left over from the initial planet-building process in another solar system with a precision that is comparable to what we could achieve in the laboratory if we had the material here on Earth,” says ESA’s Herschel project scientist Göran Pilbratt.

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NASA’s Infrared Observatory Measures Expansion Of Universe

October 4, 2012 Leave a comment

Astronomers using NASA’s Spitzer Space Telescope have announced the most precise measurement yet of the Hubble constant, or the rate at which our universe is stretching apart.

The Hubble constant is named after the astronomer Edwin P. Hubble, who astonished the world in the 1920s by confirming our universe has been expanding since it exploded into being 13.7 billion years ago. In the late 1990s, astronomers discovered the expansion is accelerating, or speeding up over time. Determining the expansion rate is critical for understanding the age and size of the universe.

Unlike NASA’s Hubble Space Telescope, which views the cosmos in visible light, Spitzer took advantage of long-wavelength infrared light to make its new measurement. It improves by a factor of 3 on a similar, seminal study from the Hubble telescope and brings the uncertainty down to 3 percent, a giant leap in accuracy for cosmological measurements. The newly refined value for the Hubble constant is 74.3 plus or minus 2.1 kilometers per second per megaparsec. A megaparsec is roughly 3 million light-years.

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UCLA Astronomers Discover Star Racing Around Black Hole At Center Of Our Galaxy

October 4, 2012 Leave a comment

UCLA astronomers report the discovery of a remarkable star that orbits the enormous black hole at the center of our Milky Way galaxy in a blistering 11-and-a-half years — the shortest known orbit of any star near this black hole.

The star, known as S0-102, may help astronomers discover whether Albert Einstein was right in his fundamental prediction of how black holes warp space and time, said research co-author Andrea Ghez, leader of the discovery team and a UCLA professor of physics and astronomy who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics.

Before this discovery, astronomers knew of only one star with a very short orbit near the black hole: S0-2, which Ghez used to call her “favorite star” and whose orbit is 16 years. (The “S” is for Sagittarius, the constellation containing the galactic center and the black hole).

“It is the tango of S0-102 and S0-2 that will reveal the true geometry of space and time near a black hole for the first time,” Ghez said. “This measurement cannot be done with one star alone.”

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Surprising Black-Hole Discovery Changes Picture Of Globular Star Clusters

October 4, 2012 1 comment

An unexpected discovery by astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) is forcing scientists to rethink their understanding of the environment in globular star clusters, tight-knit collections containing hundreds of thousands of stars.

The astronomers used the VLA to study a globular cluster called Messier 22 (M22), a group of stars more than 10,000 light-years from Earth. They hoped to find evidence for a rare type of black hole in the cluster’s center. They wanted to find what scientists call an intermediate-mass black hole, more massive than those a few or more times the Sun’s mass, but smaller than the supermassive black holes found at the cores of galaxies.

“We didn’t find what we were looking for, but instead found something very surprising — two smaller black holes,” said Laura Chomiuk, of Michigan State University and the National Radio Astronomy Observatory. “That’s surprising because most theorists said there should be at most one black hole in the cluster,” she added.

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