October 5, 2010, 7:19 AM CT

Disentangle turbulence in the solar wind

From Earth, the Sun looks like a calm, placid body that does little more than shine brightly while marching across the sky. Images from a bit closer, of course, show it's an unruly ball of hot gas that can expel long plumes out into space but even this isn't the whole story. Surrounding the Sun is a roiling wind of electrons and protons that shows constant turbulence at every size scale: long streaming jets, smaller whirling eddies, and even microscopic movements as charged particles circle in miniature orbits. Through it all, great magnetic waves and electric currents move through, stirring up the particles even more.

This solar wind is some million degrees Celsius, can move as fast as 750 kilometers (466 statute miles) per second, and so far defies a complete description by any one theory. It's hotter than expected, for one, and no one has yet agreed which of several theories offers the best explanation.

Now, the ESA/NASA Cluster mission four identical spacecraft that fly in a tight formation to provide 3-dimensional snapshots of structures around Earth has provided new information about how the protons in the solar wind are heated.

"We had a perfect window of 50 minutes," says NASA scientist Melvyn Goldstein, chief of the Geospace Physics Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. and co-author of the new paper that appeared in Physical Review Letters on September 24. "It was a time when the four Cluster spacecraft were so close together they could watch movements in the solar wind at a scale small enough that it was possible to observe the heating of protons through turbulence directly for the first time"......... Posted by: Sean      Read more         Source

August 26, 2010, 11:02 PM CT

Two Planets Transiting Same Star

NASA's Kepler Mission has discovered the first confirmed planetary system with more than one planet transiting the same star.

Today's announcement of the discovery of the two planets, Kepler 9b and 9c, is based on seven months of observations of more than 156,000 stars being monitored for subtle brightness changes as part of an ongoing search for Earth-like planets outside our solar system. Scientists designated the sun-like star Kepler-9.

The inner world, Kepler 9-b, orbits its star every 19.2 days at a distance of 13 million miles, while the outer world orbits once in 38.9 days at a distance of 21 million miles. (In comparison, Mercury has an orbital period of 88 days.) They orbit nearly in resonance, with the inner planet completing two orbits for every one of the outer planet. Both are Saturn-sized gas giants, with the inner world weighing in at 0.25 Jupiter mass (80 Earths) while the outer world is a slimmer 0.17 Jupiter mass (54 Earths).

"This is the first confirmed system of more than one planet transiting the same star," said Matthew Holman, a Kepler Mission scientist from the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. Scientists confirmed the multiple transits with radial velocity observations conducted at the W.M Keck Observatory in Hawaii......... Posted by: Sean      Read more         Source

August 25, 2010, 6:55 AM CT

Pulverized Planet Dust

Tight double-star systems might not be the best places for life to spring up, as per a newly released study using data from NASA's Spitzer Space Telescope. The infrared observatory spotted a surprisingly large amount of dust around three mature, close-orbiting star pairs. Where did the dust come from? Astronomers say it might be the aftermath of tremendous planetary collisions.

"This is real-life science fiction," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "Our data tell us that planets in these systems might not be so lucky -- collisions could be common. It's theoretically possible that habitable planets could exist around these types of stars, so if there happened to be any life there, it could be doomed."

Drake is the principal investigator of the research, reported in the Aug. 19 issue of the Astrophysical Journal Letters.

The particular class of binary, or double, stars in the study are about as snug as stars get. Named RS Canum Venaticorums, or RS CVns for short, they are separated by only about two million miles (3.2 million kilometers), or one-fiftieth the distance between Earth and our sun. The stellar pairs orbit around each other every few days, with one face on each star perpetually locked and pointed toward the other......... Posted by: Sean      Read more         Source

August 25, 2010, 6:54 AM CT

Amazing new sun images

NJIT Distinguished Professor Philip R. Goode and the Big Bear Solar Observatory (BBSO) team have achieved "first light" using a deformable mirror in what is called adaptive optics at Big Bear Solar Observatory (BBSO). Using this equipment, an image of a sunspot was published yesterday on the website of Ciel et l'Espace, as the photo of the day: http://www.cieletespace.fr/node/5752.

"This photo of a sunspot is now the most detailed ever obtained in visible light," as per Ciel et l'Espace. In September, the publication, a popular astronomy magazine, will publish several more photos of the Sun taken with BBSO's new adaptive optics system.

Goode said that the images were achieved with the 1.6 m clear aperture, off-axis New Solar Telescope (NST) at BBSO. The telescope has a resolution covering about 50 miles on the Sun's surface.

The telescope is the crown jewel of BBSO, the first facility-class solar observatory built in more than a generation in the U.S. The instrument is undergoing commissioning at BBSO.

Since 1997, under Goode's direction, NJIT has owned and operated BBSO, located in a clear mountain lake.

Typically the mountain lake is characterized by sustained atmospheric stability, which is essential for BBSO's primary interests of measuring and understanding solar complex phenomena utilizing dedicated telescopes and instruments......... Posted by: Sean      Read more         Source

August 19, 2010, 7:18 AM CT

Ancient Galaxy Cluster Still Producing Stars

Much like quiet, middle-aged baby boomers peacefully residing in some of the world's largest cities, families of some galaxies also have a hidden wild youth that they only now are revealing for the first time, as per research by astronomers at Texas A&M University.

In ongoing observations of one of the universe's earliest, most distant cluster of galaxies using NASA's Spitzer Space Telescope, an international team of scientists led by Texas A&M's Dr. Kim-Vy Tran has discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Tran, an assistant professor in the Texas A&M Department of Physics and Astronomy and member of the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and her team have spent the past four months analyzing images taken from the Multiband Imaging Photometer for Spitzer (MIPS), essentially looking back in time nearly 10 billion years at a high red-shift cluster known as CLG J02182-05102. Mere months after first discovering the cluster and the fact that it is shockingly "modern" in its appearance and size despite being observed just 4 billion years after the Big Bang, the Texas A&M-led team was able to determine that the galaxy cluster produces hundreds to thousands of new stars every year - a far higher birthrate than what is present in nearby galaxies......... Posted by: Sean      Read more         Source

August 11, 2010, 7:44 PM CT

Spotting Stellar Nurseries

Astronomers scanning the skies as part of ESO's VISTA Magellanic Cloud survey have now obtained a spectacular picture of the Tarantula Nebula in our neighbouring galaxy, the Large Magellanic Cloud. This panoramic near-infrared view captures the nebula itself in great detail as well as the rich surrounding area of sky. The image was obtained at the start of a very ambitious survey of our neighbouring galaxies, the Magellanic Clouds, and their environment.

The leader of the survey team, Maria-Rosa Cioni (University of Hertfordshire, UK) explains: "This view is of one of the most important regions of star formation in the local Universe - the spectacular 30 Doradus star-forming region, also called the Tarantula Nebula. At its core is a large cluster of stars called RMC 136, in which some of the most massive stars known are located".

ESO's VISTA telescope [1] is a new survey telescope at the Paranal Observatory in Chile (eso0949). VISTA is equipped with a huge camera that detects light in the near-infrared part of the spectrum, revealing a wealth of detail about astronomical objects that gives us insight into the inner workings of astronomical phenomena. Near-infrared light has a longer wavelength than visible light and so we cannot see it directly for ourselves, but it can pass through much of the dust that would normally obscure our view. This makes it especially useful for studying objects such as young stars that are still enshrouded in the gas and dust clouds from which they formed. Another powerful aspect of VISTA is the large area of the sky that its camera can capture in each shot......... Posted by: Sean      Read more         Source

August 11, 2010, 7:31 PM CT

Dark-matter search plunges

This month physicist Juan Collar and his associates are taking their attempt to unmask the secret identity of dark matter into a Canadian mine more than a mile underground.

The team is deploying a 4-kilogram bubble chamber at SNOLab, which is part of the Sudbury Neutrino Observatory in Ontario, Canada. A second 60-kilogram chamber will follow later this year. Scientists anticipate that dark matter particles will leave bubbles in their tracks when passing through the liquid in one of these chambers.

Dark matter accounts for nearly 90 percent of all matter in the universe. Although invisible to telescopes, scientists can observe the gravitational influence that dark matter exerts over galaxies.

"There is a lot more mass than literally meets the eye," said Collar, Associate Professor in Physics at the University of Chicago. "When you look at the matter budget of the universe, we have a big void there that we can't explain".

Likely suspects for what constitutes dark matter include Weakly Interacting Massive Particles (WIMPS) and axions. Theorists originally proposed the existence of both these groups of subatomic particles to address issues unrelated to dark matter.

"These seem to be perfect to explain all of these observations that give us this evidence for dark matter, and that makes them very appealing," Collar said......... Posted by: Sean      Read more         Source

July 16, 2010, 7:12 AM CT

Refining a cosmic clock

Physicists will soon have a better measure of the age of our galaxy, thanks to experiments described in a trio of papers appearing in the journal Physical Review C The papers report on experiments at the CERN neutron time-of-flight (n_TOF) facility and the Karlsruhe Van de Graaff accelerator that clarify the processes that affect the abundance of the element osmium-187. The element is created when rhenium-187 decays. Because rhenium-187 was produced in the first stellar explosions after the birth of the galaxy, measuring the amounts of rhenium-187 and osmium-187 we observe today can provide an estimate of the galaxy's age. In effect, the elements act as a cosmic clock that started ticking when the galaxy was born.

Unfortunately, there are various processes that can affect the amounts of osmium we measure. Uncertainties in our understanding of those processes have limited the accuracy of the cosmic clock to more than a billion years. The CERN and Karlsruhe experiments involve firing pulses of neutrons into an osmium target to determine how frequently the element is likely to capture neutrons and convert to another material. The data the scientists collected has reduced uncertainties in the rhenium-osmium cosmic clock to less than a billion years, allowing a better estimate of our roughly 14 billion year old galaxy......... Posted by: Sean      Read more         Source

July 16, 2010, 7:04 AM CT

An unusual cosmic lens

Astronomers at the California Institute of Technology (Caltech) and Ecole Polytechnique Fdrale de Lausanne (EPFL) in Switzerland have discovered the first known case of a distant galaxy being magnified by a quasar acting as a gravitational lens. The discovery, based in part on observations done at the W. M. Keck Observatory on Hawaii's Mauna Kea, is being published July 16 in the journal Astronomy & Astrophysics

Quasars, which are extraordinary luminous objects in the distant universe, are believed to be powered by supermassive black holes in the cores of galaxies. A single quasar could be a thousand times brighter than an entire galaxy of a hundred billion stars, which makes studies of their host galaxies exceedingly difficult. The significance of the discovery, the scientists say, is that it provides a novel way to understand these host galaxies.

"It is a bit like staring into bright car headlights and trying to discern the color of their rims," says Frdric Courbin of EPFL, the main author on the paper. Using gravitational lensing, he says, "we now can measure the masses of these quasar host galaxies and overcome this difficulty".

As per Einstein's general theory of relativity, if a large mass (such as a big galaxy or a cluster of galaxies) is placed along the line of sight to a distant galaxy, the part of the light that comes from the galaxy will split. Because of this, an observer on Earth will see two or more close images of the now-magnified background galaxy......... Posted by: Sean      Read more         Source

July 13, 2010, 6:53 AM CT

Image of cosmic concoction

Strangely shaped dust clouds, resembling spilled liquids, are silhouetted against a colourful background of glowing gas in this newly released Hubble image. The star-forming region NGC 2467 is a vast cloud of gas mostly hydrogen that serves as an incubator for new stars. Some of these youthful stars have emerged from the dense clouds where they were born and now shine brightly, hot and blue in this picture, but a number of others remain hidden.

The full beauty of this object and hints of the astrophysical processes at work within it are revealed in this super-sharp image from Hubble. Hot young stars that recently formed from the cloud are emitting fierce ultraviolet radiation that is causing the whole scene to glow while also sculpting the environment and gradually eroding the gas clouds. Studies have shown that most of the radiation comes from the single hot and brilliant massive star just above the centre of the image. Its fierce radiation has cleared the surrounding region and some of the next generation of stars are forming in the denser regions around the edge.

One of the most familiar star-forming regions is the Orion Nebula, which can be seen with the naked eye. NGC 2467 is a similar but more distant example. Such stellar nurseries can be seen out to considerable distances in the Universe, and their study is important in determining the distance and chemical composition of other galaxies. Some galaxies contain huge star-forming regions, which may contain tens of thousands of stars. Another dramatic example is the 30 Doradus region in the Large Magellanic Cloud......... Posted by: Sean      Read more         Source