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Archive for June 13, 2013

Hubble Uncovers Evidence For Extrasolar Planet Under Construction


Nearly 900 extrasolar planets have been confirmed to date, but now for the first time astronomers think they are seeing compelling evidence for a planet under construction in an unlikely place, at a great distance from its diminutive red dwarf star.

The keen vision of NASA’s Hubble Space Telescope has detected a mysterious gap in a vast protoplanetary disk of gas and dust swirling around the nearby star TW Hydrae, located 176 light-years away in the constellation Hydra (the Sea Serpent). The gap’s presence is best explained as due to the effects of a growing, unseen planet that is gravitationally sweeping up material and carving out a lane in the disk, like a snow plow.

Researchers, led by John Debes of the Space Telescope Science Institute in Baltimore, Md., found the gap about 7.5 billion miles from the red dwarf star. If the putative planet orbited in our solar system, it would be roughly twice Pluto’s distance from the Sun.

Full Story: http://hubblesite.org/newscenter/archive/releases/2013/20/full/
Also: http://carnegiescience.edu/news/exoplanet_formation_surprise

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NASA’s Chandra Turns Up Black Hole Bonanza In Galaxy Next Door


 Andromeda. Image Credit: X-ray: NASA/CXC/SAO/R. Barnard, Z. Lee et al.; Optical: NOAO/AURA/NSF/REU Program/B. Schoening, V. Harvey and Descubre Foundation/CAHA/OAUV/DSA/V. Peris

Andromeda. Image Credit: X-ray: NASA/CXC/SAO/R. Barnard, Z. Lee et al.; Optical: NOAO/AURA/NSF/REU Program/B. Schoening, V. Harvey and Descubre Foundation/CAHA/OAUV/DSA/V. Peris

Using more than 150 Chandra observations, spread over 13 years, researchers identified 26 black hole candidates, the largest number to date, in a galaxy outside our own. Many consider Andromeda to be a sister galaxy to the Milky Way. The two ultimately will collide, several billion years from now.

“While we are excited to find so many black holes in Andromeda, we think it’s just the tip of the iceberg,” said Robin Barnard of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and lead author of a new paper describing these results. “Most black holes won’t have close companions and will be invisible to us.”

The black hole candidates belong to the stellar mass category, meaning they formed in the death throes of very massive stars and typically have masses five to 10 times that of our sun. Astronomers can detect these otherwise invisible objects as material is pulled from a companion star and heated up to produce radiation before it disappears into the black hole.

Full Story: http://www.chandra.harvard.edu/press/13_releases/press_061213.html
Also: http://www.nasa.gov/mission_pages/chandra/news/bonanza.html

Cosmic Giants Shed New Light On Dark Matter


An international team of astronomers from Taiwan, England, and Japan has used the Subaru Telescope to measure the distribution of dark matter in fifty galaxy clusters and found that its density gradually decreases from the center of these cosmic giants to their diffuse outskirts. This new evidence about the mysterious dark matter that pervades our Universe conforms to the predictions of cold dark matter theory, known as “CDM”.

Few scientists seriously doubt the existence of dark matter, which researchers discovered almost eighty years ago. Nevertheless, astronomers cannot directly see dark matter in the night sky, and particle physicists have not yet identified a dark matter particle in their experiments. “What is dark matter?” is a big unanswered question facing astronomers and particle physicists, especially because invisible dark matter probably makes up 85% of the mass of the Universe.

“A galaxy cluster is like a huge city viewed from above during the night”, said Dr. Graham Smith (University of Birmingham, England). “Each bright city light is a galaxy, and the dark areas between the lights that appear to be empty during the night are actually full of dark matter. You can think of the dark matter in a galaxy cluster as being the infrastructure within which the galaxies live,” he explained. The team wanted to use a large sample of galaxy clusters to find out how the density of dark matter changes from the center of a typical galaxy cluster to its outskirts.

Full Story: http://www.naoj.org/Pressrelease/2013/06/12/index.html
Also: http://www.ipmu.jp/node/1633

Astronomers Use Precision Pulsar Positions To Break Record


An international team of scientists led by astronomer Adam Deller (ASTRON) have used the Very Long Baseline Array (VLBA) to set a new distance accuracy record, pegging a pulsar called PSR J2222-0137 at 871.4 light-years from Earth. They did this by observing the object over a two-year period to detect its parallax, the slight shift in apparent position against background objects when viewed from opposite ends of Earth’s orbit around the Sun. With an uncertainty less than four light-years, this distance measurement is 30 percent more accurate than that of the previous-best pulsar distance. The VLBA observations were even able to discern the orbital motion of the pulsar around its as-yet undetected companion object, despite this motion being no larger than a small coin observed at a tenth of the distance to the Moon. The results of the research have been published in The Astrophysical Journal.

Full Story: http://www.astron.nl/about-astron/press-public/news/radio-astronomers-use-precision-pulsar-positions-break-distance-recor