Archive for June, 2013

Spiral Galaxies Like Milky Way Bigger Than Thought Says CU-Boulder Study

Image courtesy NASA

Image courtesy NASA

Let’s all fist bump: Spiral galaxies like our own Milky Way appear to be much larger and more massive than previously believed, according to a new University of Colorado Boulder study by researchers using the Hubble Space Telescope.

CU-Boulder Professor John Stocke, study leader, said new observations with Hubble’s $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter. The current estimated diameter of the Milky Way, for example, is about 100,000 light-years. One light-year is roughly 6 trillion miles.

The material for galaxy halos detected by the CU-Boulder team originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process, said Stocke of CU-Boulder’s astrophysical and planetary sciences department. “This gas is stored and then recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation,” he said. “In many ways this is the ‘missing link’ in galaxy evolution that we need to understand in detail in order to have a complete picture of the process.”

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Revealed The Mystery Of The Gigantic Storm On Saturn

We now understand the nature of the giant storms on Saturn. Through the analysis of images sent from the Cassini space probe belonging to the North American and European space agencies (NASA and ESA respectively), as well as the computer models of the storms and the examination of the clouds therein, the Planetary Sciences Group of the University of the Basque Country has managed to explain the behaviour of these storms for the very first time. The article explaining the discovery, the lead author being Enrique García Melendo, researcher at the Fundació Observatori Esteve Duran – Institut de Ciències de l’Espai, of Catalonia, was published in Nature Geosciences.

Approximately once every Saturnian year – equivalent to 30 Earth years – an enormous storm is produced on the ringed planet and which affects the aspect of its atmosphere on a global scale. These gigantic storms are known as Great White Spots, due to the appearance they have on the atmosphere of the planet. The first observation of one of these was made in 1876; the Great White Spot of 2010 was the sixth one to be observed. On this occasion the Cassini space vehicle was able to obtain very high resolution images of this great meteorological structure.

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The Violent Birth Of Neutron Stars

A team of researchers at the Max Planck Institute for Astrophysics conducted the most expensive and most elaborate computer simulations so far to study the formation of neutron stars at the center of collapsing stars with unprecedented accuracy. These worldwide first three-dimensional models with a detailed treatment of all important physical effects confirm that extremely violent, hugely asymmetric sloshing and spiral motions occur when the stellar matter falls towards the center. The results of the simulations thus lend support to basic perceptions of the dynamical processes that are involved when a star explodes as supernova.

Stars with more than eight to ten times the mass of our Sun end their lives in a gigantic explosion, in which the stellar gas is expelled into the surrounding space with enormous power. Such supernovae belong to the most energetic and brightest phenomena in the universe and can outshine a whole galaxy for weeks. They are the cosmic origin of chemical elements like carbon, oxygen, silicon, and iron, of which the Earth and our bodies are made of, and which are bred in massive stars over millions of years or freshly fused in the stellar explosion.

Supernovae are also the birth places of neutron stars, those extraordinarily exotic, compact stellar remnants, in which about 1.5 times the mass of our Sun is compressed to a sphere with the diameter of Munich. This happens within fractions of a second when the stellar core implodes due to the strong gravity of its own mass. The catastrophic collapse is stopped only when the density of atomic nuclei – gargantuan 300 million tons in a sugar cube – is exceeded.

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G1.9+0.3: The Remarkable Remains Of A Recent Supernova

Credit: X-ray (NASA/CXC/NCSU/K. Borkowski et al.); Optical (DSS)

Credit: X-ray (NASA/CXC/NCSU/K. Borkowski et al.); Optical (DSS)

Astronomers estimate that a star explodes as a supernova in our Galaxy, on average, about twice per century. In 2008, a team of scientists announced they discovered the remains of a supernova that is the most recent, in Earth’s time frame, known to have occurred in the Milky Way.

The explosion would have been visible from Earth a little more than a hundred years ago if it had not been heavily obscured by dust and gas. Its likely location is about 28,000 light years from Earth near the center of the Milky Way. A long observation equivalent to more than 11 days of observations of its debris field, now known as the supernova remnant G1.9+0.3, with NASA’s Chandra X-ray Observatory is providing new details about this important event.

The source of G1.9+0.3 was most likely a white dwarf star that underwent a thermonuclear detonation and was destroyed after merging with another white dwarf, or pulling material from an orbiting companion star. This is a particular class of supernova explosions (known as Type Ia) that are used as distance indicators in cosmology because they are so consistent in brightness and incredibly luminous.

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First Transiting Planets In A Star Cluster Discovered

All stars begin their lives in groups. Most stars, including our Sun, are born in small, benign groups that quickly fall apart. Others form in huge, dense swarms that survive for billions of years as stellar clusters. Within such rich and dense clusters, stars jostle for room with thousands of neighbors while strong radiation and harsh stellar winds scour interstellar space, stripping planet-forming materials from nearby stars.

It would thus seem an unlikely place to find alien worlds. Yet 3,000 light-years from Earth, in the star cluster NGC 6811, astronomers have found two planets smaller than Neptune orbiting Sun-like stars. The discovery, published in the journal Nature, shows that planets can develop even in crowded clusters jam-packed with stars.

“Old clusters represent a stellar environment much different than the birthplace of the Sun and other planet-hosting field stars,” says lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics (CfA). “And we thought maybe planets couldn’t easily form and survive in the stressful environments of dense clusters, in part because for a long time we couldn’t find them.”

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Three Planets In Habitable Zone Of Nearby Star

June 26, 2013 1 comment

Artist's impression of the Gliese 667C system. Image Credit: ESO/M. Kornmesser

Artist’s impression of the Gliese 667C system. Image Credit: ESO/M. Kornmesser

A team of astronomers has combined new observations of Gliese 667C with existing data from HARPS at ESO’s 3.6-metre telescope in Chile, to reveal a system with at least six planets. A record-breaking three of these planets are super-Earths lying in the zone around the star where liquid water could exist, making them possible candidates for the presence of life. This is the first system found with a fully packed habitable zone.

Gliese 667C is a very well-studied star. Just over one third of the mass of the Sun, it is part of a triple star system known as Gliese 667 (also referred to as GJ 667), 22 light-years away in the constellation of Scorpius (The Scorpion). This is quite close to us — within the Sun’s neighbourhood — and much closer than the star systems investigated using telescopes such as the planet-hunting Kepler space telescope.

These planets orbit the third fainter star of a triple star system. Viewed from one of these newly found planets the two other suns would look like a pair of very bright stars visible in the daytime and at night they would provide as much illumination as the full Moon. The new planets completely fill up the habitable zone of Gliese 667C, as there are no more stable orbits in which a planet could exist at the right distance to it.

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U Re-Enlists With Astronomy Project University: Joins Sky Survey’s Fourth Phase With W.L. Eccles Grant

University of Utah astronomers will participate in a six-year project to study the formation of our Milky Way galaxy; map stars, gas and supermassive black holes in 10,000 neighbor galaxies; and chart 1 million galaxies and quasars to learn about mysterious “dark energy” that makes the universe expand.

Five years after joining the third phase of the Sloan Digital Sky Survey, or SDSS-III, Utah’s largest research university is signing up for the fourth phase of the international effort to map the heavens – thanks to a $350,000 “challenge grant” from the Willard L. Eccles Charitable Foundation and a matching $350,000 from the university.

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Astronomers Spy On Galaxies In The Raw

A CSIRO radio telescope has detected the raw material for making the first stars in galaxies that formed when the Universe was just three billion years old — less than a quarter of its current age. This opens the way to studying how these early galaxies make their first stars.

The telescope is CSIRO’s Australia Telescope Compact Array telescope near Narrabri, NSW. “It one of very few telescopes in the world that can do such difficult work, because it is both extremely sensitive and can receive radio waves of the right wavelengths,” says CSIRO astronomer Professor Ron Ekers.

The raw material for making stars is cold molecular hydrogen gas, H2. It can’t be detected directly but its presence is revealed by a ‘tracer’ gas, carbon monoxide (CO), which emits radio waves.

In one project, astronomer Dr Bjorn Emonts (CSIRO Astronomy and Space Science) and his colleagues used the Compact Array to study a massive, distant conglomerate of star-forming ‘clumps’ or ‘proto-galaxies’ that are in the process of coming together as a single massive galaxy. This structure, called the Spiderweb, lies more than ten thousand million light-years away [at a redshift of 2.16].

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Dusty Surprise Around Giant Black Hole

Artist’s impression. Credit: ESO/M. Kornmesser

Artist’s impression. Credit: ESO/M. Kornmesser

ESO’s Very Large Telescope Interferometer has gathered the most detailed observations ever of the dust around the huge black hole at the centre of an active galaxy. Rather than finding all of the glowing dust in a doughnut-shaped torus around the black hole, as expected, the astronomers find that much of it is located above and below the torus. These observations show that dust is being pushed away from the black hole as a cool wind — a surprising finding that challenges current theories and tells us how supermassive black holes evolve and interact with their surroundings.

Over the last twenty years, astronomers have found that almost all galaxies have a huge black hole at their centre. Some of these black holes are growing by drawing in matter from their surroundings, creating in the process the most energetic objects in the Universe: active galactic nuclei (AGN). The central regions of these brilliant powerhouses are ringed by doughnuts of cosmic dust dragged from the surrounding space, similar to how water forms a small whirlpool around the plughole of a sink. It was thought that most of the strong infrared radiation coming from AGN originated in these doughnuts.

But new observations of a nearby active galaxy called NGC 3783, harnessing the power of the Very Large Telescope Interferometer (VLTI) at ESO’s Paranal Observatory in Chile [2], have given a team of astronomers a surprise.

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Billion-Pixel View Of Mars Comes From Curiosity Rover

Image credit: NASA/JPL-Caltech/MSSS

Image credit: NASA/JPL-Caltech/MSSS

A billion-pixel view from the surface of Mars, from NASA’s Mars rover Curiosity, offers armchair explorers a way to examine one part of the Red Planet in great detail.

The first NASA-produced view from the surface of Mars larger than one billion pixels stitches together nearly 900 exposures taken by cameras onboard Curiosity and shows details of the landscape along the rover’s route.

The full-circle scene surrounds the site where Curiosity collected its first scoops of dusty sand at a windblown patch called “Rocknest,” and extends to Mount Sharp on the horizon.

“It gives a sense of place and really shows off the cameras’ capabilities,” said Bob Deen of the Multi-Mission Image Processing Laboratory at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “You can see the context and also zoom in to see very fine details.”

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