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May 2012
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Image of the Day: Pulsar in Supernova Remnant Sets Speed Record at 6 Million MPH




NASA's Chandra X-ray Observatory and ESA's XMM-Newton in space, and the Parkes radio telescope in Australia -- may have found the fastest moving pulsar ever seen. The evidence for this potentially record-breaking speed comes, in part, from the features highlighted in the composite image below. X-ray observations from Chandra (green) and XMM-Newton (purple) have been combined with infrared data from the 2MASS project and optical data from the Digitized Sky Survey (colored red, green and blue, but appearing in the image as white).

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EcoAlert: 100-Kilometer Wide Impact Crater Found in Greenland --Oldest Known on Planet




A 100 kilometer-wide crater has been found in Greenland, the result of a massive asteroid or comet impact a billion years before any other known collision on Earth. The previously oldest known crater on Earth formed 2 billion years ago and the chances of finding an even older impact were thought to be, literally, astronomically low.

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Saturn's Titan Harbors an Ocean of Water --Increases Odds for Life


           Titan (1)


Saturn's Titan has been considered a “unique world in the solar system” since 1908 when, the Spanish astronomer, José Comas y Solá, discovered that it had an atmosphere, something non-existent on other moons. It seems perfectly appropriate that one of the prime candidates for life in our solar system, Saturn's largest moon, Titan, should have surface lakes, lightning, shorelines, relatively thick nitrogen atmosphere -and seasons. And thanks to new Cassini data pointing to an ocean, it just become more so.

Data from NASA's Cassini spacecraft have revealed Saturn's moon Titan likely harbors a layer of liquid water under its ice shell.  Researchers saw a large amount of squeezing and stretching as the moon orbited Saturn. The Cassini team deduced that if Titan were composed entirely of stiff rock, the gravitational attraction of Saturn would cause bulges, or solid "tides," on the moon only 3 feet (1 meter) in height. Spacecraft data show Saturn creates solid tides approximately 30 feet (10 meters) in height, which suggests Titan is not made entirely of solid rocky material. 

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Did the Milky Way Have a Encounter with a Massive Dark Matter Structure 100 Million Years Ago?




"Our Milky Way had an encounter with a small galaxy or massive dark matter structure perhaps as recently as 100 million years ago," said Larry Widrow, professor at Queen’s University, part of a team of astronomers from Canada and the United States who have discovered what may well be the smoking gun of such an encounter, one that occurred close to our position in the galaxy and relatively recently, at least in the cosmological sense. "We clearly observe unexpected differences in the Milky Way’s stellar distribution above and below the Galaxy’s midplane that have the appearance of a vertical wave -- something that nobody has seen before," Widrow added.

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Mystery of the Missing Life-Giving Molecule in Space Deepens




A new search for molecular oxygen in the Orion Nebula has come up negative, leading to new ideas on what's wrong in the chemical models. Searches for interstellar molecular oxygen, O2, have a long history, and the motivation for these searches has evolved. Prior to the late 1990’s, efforts to detect O2 were driven by a desire to confirm its predicted role as a major reservoir of elemental oxygen within dense molecular clouds and as the most important gas coolant of typical clouds after carbon monoxide (CO). But O2 was never found. The SAO-led Submillimeter Wave Astronomy Satellite (SWAS) in 1998 and the Odin satellite in 2001 both failed to detect O2 toward a large number of sources at levels of a few percent of the abundances predicted by equilibrium gas-phase chemical models. Something in the chemical models was wrong, but what?

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Image of the Day: The Observable Universe in 3D




The evolution of the largest structures in the Universe are here simulated in this stunning video created on the NASA AMES' constellation of supercomputer processors. This Bolshoi simulation (based on the Lambda Cold Dark Matter model) is designed to study how dark matter halos evolved.

Credit: Anatoly Klypin / Joel Primack / Chris Henze / NASA

Violent Climate Change on an Alien Planet --A First!




Astronomers using the NASA/ESA Hubble Space Telescope have witnesseda dramatic changes in the upper atmosphere of a distant alien planet. Just after a violent flare on its parent star bathed it in intense X-ray radiation, the planet's atmosphere gave off a powerful burst of evaporation. The observations give a tantalizing glimpse of the changing climates and weather on planets outside our solar system.

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90 Billion Light Years --Evolution of Dark Matter in the Observable Universe (Video)




Jean-Michel Alimi from the French National Centre for Scientific Research (CNRS) and colleagues from the DEUS consortium, created a model of the evolution of dark mattter that covers 90 billion light years, which is the size of the universe that we are able to see, and follows 550 billion particles the mass of our Milky Way.

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Image of the Day: Odd Objects of the Helix Nebula




The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image at bottom of the page.

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Unique Object in Collision Course with Milky Way's Supermassive Black Hole




In 2011, astronomers using ESO’s Very Large Telescope have discovered a gas cloud with several times the mass of the Earth accelerating fast towards the black hole at the center of the Milky Way. This was the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed.

“The idea of an astronaut close to a black hole being stretched out to resemble spaghetti is familiar from science fiction. But we can now see this happening for real to the newly discovered cloud. It is not going to survive the experience,” explains Stefan Gillessen (MPE) the lead author of the paper.

During a 20-year program using ESO telescopes to monitor the movement of stars around the supermassive black hole at the centre of our galaxy (eso0846), a team of astronomers led by Reinhard Genzel at the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, discovered a unique new object fast approaching the black hole.

Over the last seven years, the speed of this object has nearly doubled, reaching more than 8 million km/h. It is on a very elongated orbit and in mid-2013 it will pass at a distance of only about 40 billion kilometres from the event horizon of the black hole, a distance of about 36 light-hours. This is an extremely close encounter with a supermassive black hole in astronomical terms.

This object is much cooler than the surrounding stars (only about 280 degrees Celsius), and is composed mostly of hydrogen and helium. It is a dusty, ionised gas cloud with a mass roughly three times that of the Earth. The cloud is glowing under the strong ultraviolet radiation from the hot stars around it in the crowded heart of the Milky Way.

The current density of the cloud is much higher than the hot gas surrounding the black hole. But as the cloud gets ever closer to the hungry beast, increasing external pressure will compress the cloud. At the same time the huge gravitational pull from the black hole, which has a mass four million times that of the Sun, will continue to accelerate the inward motion and stretch the cloud out along its orbit.

The cloud’s edges are already starting to shred and disrupt and it is expected to break up completely over the next few years. The astronomers can already see clear signs of increasing disruption of the cloud over the period between 2008 and 2011.* The material is also expected to get much hotter as it nears the black hole in 2013 and it will probably start to give off X-rays. There is currently little material close to the black hole so the newly-arrived meal will be the dominant fuel for the black hole over the next few years.

One explanation for the formation of the cloud is that its material may have come from nearby young massive stars that are rapidly losing mass due to strong stellar winds. Such stars literally blow their gas away. Colliding stellar winds from a known double star in orbit around the central black hole may have led to the formation of the cloud.

“The next two years will be very interesting and should provide us with extremely valuable information on the behaviour of matter around such remarkable massive objects,” concludes Reinhard Genzel.*

This research was presented in a paper “A gas cloud on its way towards the super-massive black hole in the Galactic Centre”, by S. Gillessen et al., that appeared in the 5 January 2012 issue of the journal Nature.

The Daily Galaxy via ESO