Astronomy blog

October 4, 2011, 10:05 PM CT

ALMA Opens Its Eyes

Scientists presented details about an eagerly awaited new astronomical observatory during a live webcast last Thursday with the National Science Foundation and the National Radio Astronomy Observatory (NRAO).

Astronomers Kartik Sheth and Adam Leroy of the NRAO's North American ALMA Science Center, and Brad Whitmore of the Space Telescope Science Institute, discussed details of the first scientific observing cycle with the Atacama Large Millimeter/submillimeter Array or ALMA. They explained how ALMA will contribute to understanding the universe.

The scientists also discussed the first test image released by the ALMA collaboration. The image, a composite of views of the "Antennae Galaxy" was taken with several different types of telescopes, including test data from ALMA.

The ALMA image reveals hidden starbirth nestled inside otherwise obscuring dust clouds. The Antennae galaxies are the nearest and youngest example of a prototypical merging galaxy.

Additional discussions centered on a description of astronomers' strong response to the availability of observing time on ALMA, life at the ALMA site, and how ALMA will evolve over coming months from its current complement of 16 radio telescopes to its final array of 66......... Posted by: Sean      Read more         Source

July 7, 2011, 8:55 AM CT

Big step forward for SKA

The discovery potential of the future international SKA radio telescope has been glimpsed following the commissioning of a working optical fibre link between CSIRO's Australian SKA Pathfinder (ASKAP) telescope in Western Australia, and other radio telescopes across Australia and New Zealand.

7 July 2011.

The achievement will be announced at the 2011 International SKA Forum, taking place this week in Banff, Canada.

On 29 June, six telescopes - ASKAP, three CSIRO telescopes in New South Wales, a University of Tasmania telescope and another operated by the Auckland University of Technology - were used together to observe a radio source that appears to be two black holes orbiting each other.

Data from all sites were streamed in real time to Curtin University in Perth (a node of the International Centre for Radio Astronomy Research) and there processed to make an image.

This ability to successfully link antennas (dishes) over large distances will be vital for the future $2.5 billion SKA telescope, which will have several thousand antennas, up to 5500 km apart, working together as a single telescope. Linking antennas in such a manner allows astronomers to see distant galaxies in more detail.

"We now have an SKA-scale network in Australia and New Zealand: a combination of CSIRO and NBN-supported fibre and the existing AARNET and KAREN research and education networks," said SKA Director for Australasia Dr Brian Boyle......... Posted by: Sean      Read more         Source

July 5, 2011, 8:07 PM CT

Final space shuttle to carry 5 CU-Boulder-built payloads

The University of Colorado Boulder is involved with five different space science payloads ranging from antibody tests that may lead to new bone-loss therapys to an experiment to improve vaccine effectiveness for combating salmonella when Atlantis thunders skyward July 8 on the last of NASA's 135 space shuttle missions.

One experiment, sponsored by the global pharmaceutical companies Amgen and UCB, will test an antibody to sclerostin -- a protein that has a negative effect on bone formation, mass and strength -- on lab mice flying on the shuttle. Scientists on the project hope the sclerostin antibody therapy will inhibit the action of sclerostin.

The research team hopes the findings may lead to potential therapeutic therapys for astronauts, who suffer significant bone loss during spaceflight, particularly on long-term missions. They also might provide insight for future research in the prevention and therapy of skeletal fragility that appears to be caused by stroke, cerebral palsy, muscular dystrophy, spinal cord injury and reduced physical activity. Amgen is headquartered in Thousand Oaks, Calif., while UCB is headquartered in Brussels, Belgium.

There are seven co-principal researchers on the sclerostin antibody experiment, including Louis Stodieck, director of CU-Boulder's BioServe Space Technologies and a faculty member in the aerospace engineering sciences department. The research team includes a second CU-Boulder co-principal investigator, Assistant Professor Virginia Ferguson of mechanical engineering, an expert in biomaterials, including bone......... Posted by: Sean      Read more         Source

June 5, 2011, 8:50 PM CT

Jupiter's foray robbed Mars of mass

Planetary researchers have long wondered why Mars is only about half the size and one-tenth the mass of Earth. As next-door neighbors in the inner solar system, probably formed about the same time, why isn't Mars more like Earth and Venus in size and mass? A paper reported in the journal Nature this week provides the first cohesive explanation and, by doing so, reveals an unexpected twist in the early lives of Jupiter and Saturn as well.

Dr. Kevin Walsh, a research scientist at Southwest Research Institute� (SwRI�), led an international team performing simulations of the early solar system, demonstrating how an infant Jupiter may have migrated to within 1.5 astronomical units (AU, the distance from the Sun to the Earth) of the Sun, stripping a lot of material from the region and essentially starving Mars of formation materials.

"If Jupiter had moved inwards from its birthplace down to 1.5 AU from the Sun, and then turned around when Saturn formed as other models suggest, eventually migrating outwards towards its current location, it would have truncated the distribution of solids in the inner solar system at about 1 AU and explained the small mass of Mars," says Walsh. "The problem was whether the inward and outward migration of Jupiter through the 2 to 4 AU region could be compatible with the existence of the asteroid belt today, in this same region. So, we started to do a huge number of simulations......... Posted by: Sean      Read more         Source

April 29, 2011, 8:39 AM CT

Swift and Hubble probe asteroid collision debris

Late last year, astronomers noticed an asteroid named Scheila had unexpectedly brightened, and it was sporting short-lived plumes. Data from NASA's Swift satellite and Hubble Space Telescope showed these changes likely occurred after Scheila was struck by a much smaller asteroid.

"Collisions between asteroids create rock fragments, from fine dust to huge boulders, that impact planets and their moons," said Dennis Bodewits, an astronomer at the University of Maryland in College Park and main author of the Swift study. "Yet this is the first time we've been able to catch one just weeks after the smash-up, long before the evidence fades away".

Asteroids are rocky fragments believed to be debris from the formation and evolution of the solar system approximately 4.6 billion years ago. Millions of them orbit the sun between Mars and Jupiter in the main asteroid belt. Scheila is approximately 70 miles across and orbits the sun every five years.

"The Hubble data are most simply explained by the impact, at 11,000 mph, of a previously unknown asteroid about 100 feet in diameter," said Hubble team leader David Jewitt at the University of California in Los Angeles. Hubble did not see any discrete collision fragments, unlike its 2009 observations of P/2010 A2, the first identified asteroid collision......... Posted by: Sean      Read more         Source

April 5, 2011, 7:03 PM CT

Frozen comet had a watery pas

For the first time, researchers have found convincing evidence for the presence of liquid water in a comet, shattering the current paradigm that comets never get warm enough to melt the ice that makes up the bulk of their material.

"Current thinking suggests that it is impossible to form liquid water inside of a comet," said Dante Lauretta, an associate professor of cosmochemistry and planet formation at the UA's Lunar and Planetary Laboratory. Lauretta is the principal investigator of the UA team involved in analysis of samples returned by NASA's Stardust mission.

UA graduate student Eve Berger, who led the study, and her colleagues from Johnson Space Center and the Naval Research Laboratory made the discovery analyzing dust grains brought back to Earth from comet Wild-2 as part of the Stardust mission. Launched in 1999, the Stardust spacecraft scooped up tiny particles released from the comet's surface in 2004 and brought them back to Earth in a capsule that landed in Utah two years later.

"In our samples, we found minerals that formed in the presence of liquid water," Berger said. "At some point in its history, the comet must have harbored pockets of water".

The discovery is to be published in an upcoming online edition of the journal Geochimica et Cosmochimica Acta........ Posted by: Sean      Read more         Source

March 31, 2011, 7:07 AM CT

A look inside red giant stars

NASA's Kepler Mission is giving astronomers such a clear view of changes in star brightness that they can now see clues about what's happening inside red giant stars.

"No one anticipated seeing this before the mission launched," said Steve Kawaler, an Iowa State University professor of physics and astronomy and a leader of the Kepler Asteroseismic Investigation. "That we could see so clearly down below a red giant star's surface was unexpected".

The astronomers' preliminary findings appear in two papers:

"Kepler Detected Gravity-Mode Period Spacings in a Red Giant Star," published online March 17 in the Brevia section of the journal Science The paper's principal author is Paul Beck of Leuven University in Belgium.

"Gravity Modes as a way to Distinguish between Hydrogen- and Helium-burning Red Giant Stars," reported in the Letters section of the March 31 edition of Nature The paper's principal author is Timothy Bedding of the University of Sydney in Australia.

Both papers describe how Kepler tracks tiny, regular changes in star brightness. Their regularity resembles steady drumbeats at different, precise rhythms. Each rhythm can be thought of as an individual tooth of a comb. Astronomers have studied those oscillations from ground-based telescopes to determine star basics such as mass and radius. But they noticed departures from the steady patterns in the Kepler data � "dandruff on the comb," Kawaler said......... Posted by: Sean      Read more         Source

March 30, 2011, 7:05 AM CT

The rose-red glow of star formation

The object dominating this image may resemble a pool of spilled blood, but rather than being linked to death, such regions of ionised hydrogen -- known as HII regions -- are sites of creation with high rates of recent star birth. NGC 371 is an example of this; it is an open cluster surrounded by a nebula. The stars in open clusters all originate from the same diffuse HII region, and over time the majority of the hydrogen is used up by star formation, leaving behind a shell of hydrogen such as the one in this image, along with a cluster of hot young stars.

The host galaxy to NGC 371, the Small Magellanic Cloud, is a dwarf galaxy a mere 200 000 light-years away, which makes it one of the closest galaxies to the Milky Way. In addition, the Small Magellanic Cloud contains stars at all stages of their evolution; from the highly luminous young stars found in NGC 371 to supernova remnants of dead stars. These energetic youngsters emit copious amounts of ultraviolet radiation causing surrounding gas, such as leftover hydrogen from their parent nebula, to light up with a colourful glow that extends for hundreds of light-years in every direction. The phenomenon is depicted beautifully in this image, taken using the FORS1 instrument on ESO's Very Large Telescope (VLT).

Open clusters are by no means rare; there are numerous fine examples in our own Milky Way. However, NGC 371 is of particular interest due to the unexpectedly large number of variable stars it contains. These are stars that change in brightness over time. A especially interesting type of variable star, known as slowly pulsating B stars, can also be used to study the interior of stars through asteroseismology [1], and several of these have been confirmed in this cluster. Variable stars play a pivotal role in astronomy: some types are invaluable for determining distances to far-off galaxies and the age of the Universe......... Posted by: Sean      Read more         Source

March 25, 2011, 7:28 AM CT

Clearest Picture Yet of Perseus Galaxy Cluster

X-ray observations made by the Suzaku observatory provide the clearest picture to date of the size, mass and chemical content of a nearby cluster of galaxies. The study also provides the first direct evidence that million-degree gas clouds are tightly gathered in the cluster's outskirts.

Suzaku is sponsored by the Japan Aerospace Exploration Agency (JAXA) with contributions from NASA and participation by the international scientific community. The findings will appear in the March 25 issue of the journal Science.

Galaxy clusters are millions of light-years across, and most of their normal matter comes in the form of hot X-ray-emitting gas that fills the space between the galaxies.

"Understanding the content of normal matter in galaxy clusters is a key element for using these objects to study the evolution of the universe," explained Adam Mantz, a co-author of the paper at NASA's Goddard Space Flight Center in Greenbelt, Md.

Clusters provide independent checks on cosmological values established by other means, such as galaxy surveys, exploding stars and the cosmic microwave background, which is the remnant glow of the Big Bang. The cluster data and the other values didn't agree.

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) explored the cosmic microwave background and established that baryons -- what physicists call normal matter -- make up only about 4.6 percent of the universe. Yet prior studies showed that galaxy clusters seemed to hold even fewer baryons than this amount......... Posted by: Sean      Read more         Source

March 25, 2011, 7:25 AM CT

A millisecond from doom

ESA's Integral gamma-ray observatory has spotted extremely hot matter just a millisecond before it plunges into the oblivion of a black hole. But is it really doomed? These unique observations suggest that some of the matter appears to be making a great escape.

No one would want to be so close to a black hole. Just a few hundred kilometres away from its deadly surface, space is a maelstrom of particles and radiation. Vast storms of particles are falling to their doom at close to the speed of light, raising the temperature to millions of degrees.

Ordinarily, it takes just a millisecond for the particles to cross this final distance but hope appears to be at hand for a small fraction of them.

Thanks to the new Integral observations, astronomers now know that this chaotic region is threaded by magnetic fields.

This is the first time that magnetic fields have been identified so close to a black hole. Most importantly, Integral shows they are highly structured magnetic fields that are forming an escape tunnel for some of the doomed particles.

Philippe Laurent, CEA Saclay, France, and his colleagues made the discovery by studying the nearby black hole, Cygnus X-1, which is ripping a companion star to pieces and feeding on its gas.

Their evidence points to the magnetic field being strong enough to tear away particles from the black hole's gravitational clutches and funnel them outwards, creating jets of matter that shoot into space. The particles in these jets are being drawn into spiral trajectories as they climb the magnetic field to freedom and this is affecting a property of their gamma-ray light known as polarisation......... Posted by: Sean      Read more         Source

March 18, 2011, 6:03 PM CT

Is space like a chessboard?

Physicists at UCLA set out to design a better transistor and ended up discovering a new way to think about the structure of space.

Space is commonly considered infinitely divisible � given any two positions, there is always a position halfway between. But in a recent study aimed at developing ultra-fast transistors using graphene, scientists from the UCLA Department of Physics and Astronomy and the California NanoSystems Institute show that dividing space into discrete locations, like a chessboard, may explain how point-like electrons, which have no finite radius, manage to carry their intrinsic angular momentum, or "spin." .

While studying graphene's electronic properties, professor Chris Regan and graduate student Matthew Mecklenburg observed that a particle can acquire spin by living in a space with two types of positions � dark tiles and light tiles. The particle seems to spin if the tiles are so close together that their separation cannot be detected.

"An electron's spin might arise because space at very small distances is not smooth, but rather segmented, like a chessboard," Regan said.

Their findings appear in the March 18 edition of the journal Physical Review Letters.

In quantum mechanics, "spin up" and "spin down" refer to the two types of states that can be assigned to an electron. That the electron's spin can have only two values � not one, three or an infinite number � helps explain the stability of matter, the nature of the chemical bond and a number of other fundamental phenomena......... Posted by: Sean      Read more         Source

March 17, 2011, 10:52 PM CT

Seasonal rains on Titan

As spring continues to unfold on Saturn, April showers on the planet's largest moon, Titan, have brought methane rain to its equatorial deserts, as revealed in images captured by NASA's Cassini spacecraft.

This is the first time researchers have obtained existing evidence of rain soaking Titan's surface at low latitudes. The observations are released recently in the journal Science

"Titan continues to surprise and amaze us," said Alfred McEwen, a planetary scientist at the UA's Lunar and Planetary Lab and a co-author on the paper. "After years of dry weather in the tropics, an area the size of Arizona and New Mexico combined was darkened by methane rain over a period of just a few weeks".

Extensive rain from large cloud systems, spotted by Cassini's cameras in late 2010, has apparently darkened the surface of the moon. The best explanation is these areas remained wet after methane rainstorms.

The new findings, combined with earlier results reported in Geophysical Research Letters last month, show the weather systems of Titan's thick atmosphere and the changes wrought on the moon's surface are affected by the changing seasons.

"It's amazing to be watching such familiar activity as rainstorms and seasonal changes in weather patterns on a distant, icy satellite," said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Md., and main author of today's publication. "These observations are helping us to understand how Titan works as a system, as well as similar processes on our own planet"......... Posted by: Sean      Read more         Source

March 15, 2011, 7:30 AM CT

Hubble snaps close-up of the Tarantula

The wispy arms of the Tarantula Nebula were originally thought to resemble spindly spider legs, giving the nebula its unusual name. The part of the nebula visible in this image from Hubble's Advanced Camera for Surveys is criss-crossed with tendrils of dust and gas churned up by recent supernovae. These supernova remnants include NGC 2060, visible above and to the left of the centre of this image, which contains the brightest known pulsar.

The tarantula's bite goes beyond NGC 2060. Near the edge of the nebula, outside the frame, below and to the right, lie the remains of supernova SN 1987a, the closest supernova to Earth to be observed since the invention of telescopes in the 17th century. Hubble and other telescopes have been returning to spy on this stellar explosion regularly since it blew up in 1987, and each subsequent visit shows an expanding shockwave lighting up the gas around the star, creating a pearl necklace of glowing pockets of gas around the remains of the star. SN 1987a is visible in wide field images of the nebula, such as that taken by the MPG/ESO 2.2-metre telescope.

Together with dying stars, the Tarantula Nebula is packed with young stars which have recently formed from the nebula's supply of hydrogen gas. These toddler-stars shine forth with intense ultraviolet light that ionises the gas, making it light up red. The light is so intense that eventhough around 170 000 light-years distant, and outside the Milky Way, the Tarantula Nebula is nevertheless visible without a telescope on a dark night to Earth-bound observers. This nebula might be far away, but it is the most luminous example of its type that astronomers have observed in the local Universe......... Posted by: Sean      Read more         Source

March 1, 2011, 9:21 PM CT

NASA's Glory Satellite scheduled for launch March 4

NASA's Glory spacecraft is scheduled for launch on Friday, March 4. Technical issues with ground support equipment for the Taurus XL launch vehicle led to the scrub of the original Feb. 23 launch attempt. Those issues have been resolved.

The March 4 liftoff from Vandenberg Air Force Base, Calif., is targeted for 5:09:43 a.m. EST, in the middle of a 48-second launch window. Spacecraft separation occurs 13 minutes after launch.

Data from the Glory mission will allow researchers to better understand how the sun and tiny atmospheric particles called aerosols affect Earth's climate. The Taurus XL also carries the first of NASA's Educational Launch of Nanosatellite missions. This auxiliary payload contains three small satellites called CubeSats, which were designed and created by university and college students.

NASA Television will carry launch coverage beginning March 4 at 3:30 a.m. EST. This coverage will be streamed live online at:

http://www.nasa.gov/ntv.

Real-time updates of countdown and launch milestones will be posted on NASA's launch blog beginning March 4 at 3:30 a.m. EST at:

http://www.nasa.gov/glory......... Posted by: Sean      Read more         Source

February 27, 2011, 7:25 PM CT

January's Eclipse in Dubai

On 4 January 2011, the people of Dubai had the exciting opportunity to view a partial solar eclipse during the afternoon. Just after noon, viewers could see the celestial body passing over the sun, creating a partial eclipse that lasted for a few hours. This was the first partial eclipse viewed in Dubai since 2008. A full solar eclipse has not occurred since 1999. The next solar eclipse will happen in 2019.

Viewers gathered at the Burj Steps at the Dubai Mall. The solar eclipse began in Jerusalem earlier in the day and was not viewable in Dubai until 12:11 pm.

Culturally, people in Dubai have always worried about the effects of a solar eclipse on unborn children. In the past, when there was to be a full eclipse, women were kept inside if they were pregnant. While this belief goes back hundreds of years, there were actually people calling to see if it was safe for pregnant women to view the January eclipse. They were told that since it was a partial eclipse, it would be safe for them to view the event.

The eclipse obscured about 34 percent of the sun. During the maximum eclipse, the sun was obscured for 11 minutes and eight seconds. Astronomers state that there will not be another solar eclipse that lasts this long until December of 3043. Most normal solar eclipses do not last any longer than 5 minutes, so this occurrence was very rare.

Thousands of people from around the world were booking cheap flights to Dubai just to get a glimpse of this eclipse. The event actually attracted many tourists to the area during eclipse time.

Viewers were warned not to look at the sun directly as the rays can be harmful to the eye. Other than that, the solar eclipse was perfectly safe to view. This celestial event attracted thousands of people from all locations around the globe. Many booked last minute flights just to see this amazing event. Seeing an eclipse that lasted for a record amount of time is something that will happen only once on a lifetime.

The eclipse in Dubai may have been just another partial solar eclipse to some people, but for others it was a very exciting event and one of the rare ones in recent years. Even though this area saw another eclipse just a few years back, it was a drop in the ocean compared to this 11 minute eclipse.

Dubai is known for many things around the world, mainly for its unique architecture and wealth. Now, it is can add solar eclipse on to its increasingly long list of happenings. The next total solar eclipse will not occur until 2019. There may be some partial eclipses in the meantime, but nothing that will ever compare to what happened in Dubai in January. This was truly a memorable experience for all who viewed it and will be one of the most talked about partial solar eclipses for quite some time. With the average eclipse maxing out at 5 minutes, this 11 minute phenomena will go down in the history books as being one of the longest eclipses on record.
Posted by: Sean      Read more         Source

February 14, 2011, 7:09 AM CT

2-timing spacecraft has date with another comet

NASA's Stardust spacecraft, equipped with the University of Chicago's Dust Flux Monitor Instrument (DFMI), is hurtling at more than 24,000 miles an hour toward a Valentine's Day encounter with comet Tempel 1.

Stardust will approach to within 124 miles of Tempel 1 at 10:56 p.m. CST Monday, Feb. 14. The spacecraft flew within 150 miles of comet Wild 2 in 2004, when it collected thousands of tiny dust particles streaming from the comet's nucleus for laboratory analysis.

The spacecraft dropped off the samples in a canister that parachuted onto the desert salt flats of Utah in January 2006 following a journey of nearly approximately 3.5 billion miles. But Stardust, still healthy and with fuel to spare, soon went back onto the interplanetary market, looking for a second mission.

The mission will be the first to allow Thanasas Economou, Senior Scientist at UChicago's Enrico Fermi Institute, and his fellow members of the Stardust-NExT (New Exploration of Tempel) science team to look for changes on a comet's surface that occurred following an orbit around the sun. They will compare Stardust's data from Tempel 1 with findings from a prior probe that also studied that comet.

"We are very excited that we can visit a second comet�comet Tempel 1�with the same spacecraft after we visited the Wild 2 comet in 2004," Economou said. "The Dust Flux Monitor Instrument is healthy and ready to take another look at this comet."........ Posted by: Sean      Read more         Source

February 1, 2011, 8:01 AM CT

Tracking the origins of speedy space particles

Time History of Events and Macroscale Interaction during Substorms (THEMIS) spacecraft combined with computer models have helped track the origin of the energetic particles in Earth's magnetic atmosphere that appear during a kind of space weather called a substorm. Understanding the source of such particles and how they are shuttled through Earth's atmosphere is crucial to better understanding the Sun's complex space weather system and thus protect satellites or even humans in space.

The results show that these speedy electrons gain extra energy from changing magnetic fields far from the origin of the substorm that causes them. THEMIS, which consists of five orbiting satellites, helped provide these insights when three of the spacecraft traveled through a large substorm on February 15, 2008. This allowed researchers to track changes in particle energy over a large distance. The observations were consistent with numerical models showing an increase in energy due to changing magnetic fields, a process known as betatron acceleration.

"The origin of fast electrons in substorms has been a puzzle," says Maha Ashour-Abdalla, the main author of a Nature Physics paper that appeared online on January 30, 2011 on the subject and a physicist at the University of California, Los Angeles. "It hasn't been clear until now if they got their burst of speed in the middle of the storm, or from some place further away"......... Posted by: Sean      Read more         Source

January 28, 2011, 7:53 PM CT

Research on Asteroid Deflection

So you think global warming is a big problem? What could happen if a 25-million-ton chunk of rock slammed into Earth? When something similar happened 65 million years ago, the dinosaurs and other forms of life were wiped out.

"A collision with an object of this size traveling at an estimated 30,000 to 40,000 mile per hour would be catastrophic," as per NASA researcher and New York City College of Technology (City Tech) Associate Professor of Physics Gregory L. Matloff. His recommendation? "Either destroy the object or alter its trajectory".

Dr. Matloff, whose research includes the best means to avert such a disaster, believes that diverting such objects is the wisest course of action. In 2029 and 2036, the asteroid Apophis (named after the Egyptian god of darkness and the void), at least 1,100 feet in diameter, 90 stories tall, and weighing an estimated 25 million tons, will make two close passes by Earth at a distance of about 22,600 miles.

"We don't always know this far ahead of time that they're coming," Dr. Matloff says, "but an Apophis impact is very unlikely." If the asteroid did hit Earth, NASA estimates, it would strike with 68,000 times the force of the atom bomb that leveled Hiroshima. A possibility also exists that when Apophis passes in 2029, heating as it approaches the sun, it could fragment or emit a tail, which would act like a rocket, unpredictably changing its course. If Apophis or its remnants enter one of two "keyholes" in space, impact might happen when it returns in 2036......... Posted by: Sean      Read more         Source

January 16, 2011, 9:57 PM CT

The Best Way to Measure Dark Energy

Dark energy is a mysterious force that pervades all space, acting as a "push" to accelerate the Universe's expansion. Despite being 70 percent of the Universe, dark energy was only discovered in 1998 by two teams observing Type Ia supernovae. A Type 1a supernova is a cataclysmic explosion of a white dwarf star.

These supernovae are currently the best way to measure dark energy because they are visible across intergalactic space. Also, they can function as "standard candles" in distant galaxies since the intrinsic brightness is known. Just as drivers estimate the distance to oncoming cars at night from the brightness of their headlights, measuring the apparent brightness of a supernova yields its distance (fainter is farther). Measuring distances tracks the effect of dark energy on the expansion of the Universe.

The best way of measuring dark energy just got better, thanks to a newly released study of Type Ia supernovae led by Ryan Foley of the Harvard-Smithsonian Center for Astrophysics. He has found a way to correct for small variations in the appearance of these supernovae, so that they become even better standard candles. The key is to sort the supernovae based on their color.

"Dark energy is the biggest mystery in physics and astronomy today. Now, we have a better way to tackle it," said Foley, who is a Clay Fellow at the Center. He presented his findings in a press conference at the 217th meeting of the American Astronomical Society......... Posted by: Sean      Read more         Source

January 16, 2011, 9:53 PM CT

Physicists discover Crab nebula is slowly dimming

The Crab Nebula, once considered to be a source of energy so stable that astronomers used it to calibrate their instruments, is dimming. LSU physicists Mike Cherry, Gary Case and graduate student James Rodi, together with an international team of colleagues using the Gamma-ray Burst Monitor, or GBM, on NASA's Fermi gamma-ray space telescope, discovered the anomaly. This revelation has proven astonishing for astronomers.

The Crab Nebula, one of the most studied objects in the sky, is the wreckage of a star that exploded in 1054. Considered a cornerstone of astronomical research, it even inspired its own unit of measurement, the "millicrab," which is used as a standard for measuring the intensity from other high-energy sources.

The GBM instrument was launched into orbit in summer 2008. This summer, the researchers were working on a catalog of the high energy X-ray and gamma ray signals detected mainly from sources in the galaxy powered by black holes and neutron stars. As they were preparing the catalog, which has been accepted for publication in the Astrophysical Journal, they realized that the intensity coming from the Crab Nebula was dimming.

"We were using the Crab as our calibration source and comparing the other high energy sources to it," said Case. "But as we collected more and more data, we noticed that the intensity we were measuring for the Crab was going down. This was a rather startling discovery, and it took awhile for us to believe it"......... Posted by: Sean      Read more         Source

January 16, 2011, 9:49 PM CT

Torrent of Star Formation

A new Chandra X-ray Observatory image of Messier 82, or M82, shows the result of star formation on overdrive. M82 is located about 12 million light years from Earth and is the nearest place to us where the conditions are similar to those when the Universe was much younger with lots of stars forming.

M82 is a so-called starburst galaxy, where stars are forming at rates that are tens or even hundreds of times higher than in a normal galaxy. The burst of star birth appears to be caused by a close encounter or collision with another galaxy, which sends shock waves rushing through the galaxy. In the case of M82, astronomers believe that a brush with its neighbor galaxy M81 millions of years ago set off this torrent of star formation.

M82 is seen nearly edge-on with its disk crossing from about 10 o'clock to about 4 o'clock in this image from Chandra (where low, medium, and high-energy X-rays are colored red, green, and blue respectively.) Among the 104 point-like X-ray sources in the image, eight so far have been observed to be very bright in X-rays and undergo clear changes in brightness over periods of weeks and years. This means they are excellent candidates to be black holes pulling material from companion stars that are much more massive than the Sun. Only a handful of such binary systems are known in the Local Group of galaxies containing the Milky Way and M31......... Posted by: Sean      Read more         Source

January 12, 2011, 6:33 PM CT

Taking the pulse of a black hole system

Using two NASA X-ray satellites, astronomers have discovered what drives the "heartbeats" seen in the light from an unusual black hole system. These results give new insight into the ways that black holes can regulate their intake and severely curtail their growth.

This study examined GRS 1915+105 (GRS 1915 for short), a binary system in the Milky Way galaxy containing a black hole about 14 times more massive than the Sun that is feeding off material from a companion star. As this material falls towards the black hole, it forms a swirling disk that emits X-rays. The black hole in GRS 1915 has been estimated to rotate at the maximum possible rate, allowing material in the inner disk to orbit very close to the black hole, at a radius only 20% larger than the event horizon, where the material travels at 50% the speed of light.

Using the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE), scientists monitored this black hole system over a period of eight hours. As they watched, GRS 1915 gave off a short, bright pulse of X-ray light approximately every 50 seconds, varying in brightness by a factor of about three. This type of rhythmic cycle closely resembles an electrocardiogram of a human heart -- though at a slower pace.

"Trying to understand the physics of this 'heartbeat state' is a little like trying to understand how a person's heart beats by watching changes in the blood flow through their veins," said Joey Neilsen, a graduate student at Harvard University, who presented these results from his dissertation at the American Astronomical Society (AAS) meeting in Seattle, Wash......... Posted by: Sean      Read more         Source

January 11, 2011, 6:27 AM CT

Missing link between young and old galaxies

University of California, Berkeley, astronomers may have found the missing link between gas-filled, star-forming galaxies and older, gas-depleted galaxies typically characterized as "red and dead."

In a poster to be presented this week at the American Astronomical Society meeting in Seattle, UC Berkeley astronomers report that a long-known "early-type" galaxy, NGC 1266, is expelling molecular gas, mostly hydrogen, from its core.

Astronomers have long recognized the distinction between early-type red and dead galaxies, believed to be largely devoid of gas and dust and thus not forming stars, and galaxies that are currently forming stars from the raw material molecular hydrogen. One of the outstanding problems in astronomy is how galaxies evolve from being star-forming spirals to red and dead.

With such a rapid outflow � about 13 solar masses per year traveling at up to 400 kilometers per second � the galaxy NGC 1266 could easily shed all of its molecular gas in less than 100 million years, equivalent to about one percent the age of the Milky Way, as per the researchers.

"This is the first example of an early-type galaxy where all the molecular gas � the star-forming gas � is concentrated in the nucleus and where we have such a high-resolution picture of what's going on with the molecular gas in the core," said Leo Blitz, UC Berkeley professor of astronomy. "We see molecular gas being expelled at speeds that will allow it to escape from the galaxy and return to the intergalactic medium, and we see the reservoir of gas from which it's drawing. That tells us that if things go on at the current rate, the gas will only last another 85 million more years"......... Posted by: Sean      Read more         Source

January 6, 2011, 6:16 PM CT

Longstanding Mystery of Sun's Hot Outer Atmosphere

One of the most enduring mysteries in solar physics is why the Sun's outer atmosphere, or corona, is millions of degrees hotter than its surface.

Now researchers believe they have discovered a major source of hot gas that replenishes the corona: jets of plasma shooting up from just above the Sun's surface.

The finding addresses a fundamental question in astrophysics: how energy is moved from the Sun's interior to create its hot outer atmosphere.

"It's always been quite a puzzle to figure out why the Sun's atmosphere is hotter than its surface," says Scott McIntosh, a solar physicist at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who was involved in the study.

"By identifying that these jets insert heated plasma into the Sun's outer atmosphere, we can gain a much greater understanding of that region and possibly improve our knowledge of the Sun's subtle influence on the Earth's upper atmosphere".

The research, results of which are published this week in the journal Science, was conducted by researchers from Lockheed Martin's Solar and Astrophysics Laboratory (LMSAL), NCAR, and the University of Oslo. It was supported by NASA and the National Science Foundation (NSF), NCAR's sponsor......... Posted by: Sean      Read more         Source

January 5, 2011, 6:44 AM CT

VISTA stares deeply into the blue lagoon

This new infrared image of the Lagoon Nebula was captured as part of a five-year study of the Milky Way using ESO's VISTA telescope at the Paranal Observatory in Chile. This is a small piece of a much larger image of the region surrounding the nebula, which is, in turn, only one part of a huge survey.

Astronomers are currently using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) to scour the Milky Way's central regions for variable objects and map its structure in greater detail than ever before. This huge survey is called VISTA Variables in the Via Lactea (VVV) [1]. The new infrared image presented here was taken as part of this survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8, see eso0936), which lies about 4000-5000 light-years away in the constellation of Sagittarius (the Archer).

Infrared observations allow astronomers to peer behind the veil of dust that prevents them from seeing celestial objects in visible light. This is because visible light, which has a wavelength that is about the same size as the dust particles, is strongly scattered, but the longer wavelength infrared light can pass through the dust largely unscathed. VISTA, with its 4.1-metre diameter mirror � the largest survey telescope in the world � is dedicated to surveying large areas of the sky at near-infrared wavelengths deeply and quickly. It is therefore ideally suited to studying star birth......... Posted by: Sean      Read more         Source

December 29, 2010, 6:30 AM CT

SOHO Spots 2000th Comet

As people on Earth celebrate the holidays and prepare to ring in the New Year, an ESA/NASA spacecraft has quietly reached its own milestone: on December 26, the Solar and Heliospheric Observatory (SOHO) discovered its 2000th comet.

Drawing on help from citizen researchers around the world, SOHO has become the single greatest comet finder of all time. This is all the more impressive since SOHO was not specifically designed to find comets, but to monitor the sun.

"Since it launched on December 2, 1995 to observe the sun, SOHO has more than doubled the number of comets for which orbits have been determined over the last three hundred years," says Joe Gurman, the U.S. project scientist for SOHO at NASA's Goddard Space Flight Center in Greenbelt, Md.

Of course, it is not SOHO itself that discovers the comets -- that is the province of the dozens of amateur astronomer volunteers who daily pore over the fuzzy lights dancing across the pictures produced by SOHO's LASCO (or Large Angle and Spectrometric Coronagraph) cameras. Over 70 people representing 18 different countries have helped spot comets over the last 15 years by searching through the publicly available SOHO images online.

The 1999th and 2000th comet were both discovered on December 26 by Michal Kusiak, an astronomy student at Jagiellonian University in Krakow, Poland. Kusiak found his first SOHO comet in November 2007 and has since found more than 100......... Posted by: Sean      Read more         Source

December 16, 2010, 7:22 AM CT

About gamma-ray bursts

Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow.

While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Prior studies had suggested that obscuring dust between the burst and us might also explain why they were so dim.

"Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's main author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei Mnchen, Gera number of.

NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the newly released study, astronomers combined Swift data with new observations made using GROND [2] a dedicated gamma-ray burst follow-up observation instrument, which is attached to the 2.2-metre MPG/ESO telescope at La Silla in Chile. In doing so, astronomers have conclusively solved the puzzle of the missing optical afterglow......... Posted by: Sean      Read more         Source

December 13, 2010, 6:53 AM CT

How Iapetus got its ridge

For centuries, people wondered how the leopard got its spots. The consensus is pretty solid that evolution played a major role.

But it's only been five years since the arrival of high-resolution Cassini Mission images of Saturn's bizarre moon Iapetus that the international planetary community has pondered the unique walnut shape of the large (735 kilometer radius) body, considered by a number of to be one of the most astonishing features in the solar system.

And there's no consensus as to how a mysterious large ridge that covers more than 75 percent of the moon's equator was formed. It's been a tough nut to crack.

But now a team including an outer solar system specialist from Washington University in St. Louis has proposed a giant impact explains the ridge, up to 20 kilometers tall and 100 kilometers wide.

William B. McKinnon, PhD, Washington University professor of earth and planetary sciences in Arts & Sciences, and his former doctoral student, Andrew Dombard, PhD, associate professor of earth and environmental sciences at the University of Illinois Chicago (UIC), propose that at one time Iapetus itself had a satellite, or moon, created by a giant impact with another big body. The sub-satellite's orbit, they say, would have decayed because of tidal interactions with Iapetus, and it would have gradually migrated towards Iapetus. At some point, the scientists say, the tidal forces would have torn the sub-satellite apart, forming a ring of debris around Iapetus that would eventually slam into the moon near its equator......... Posted by: Sean      Read more         Source

December 8, 2010, 6:58 AM CT

The globular cluster Messier 107

The globular cluster Messier 107, also known as NGC 6171, is a compact and ancient family of stars that lies about 21 000 light-years away. Messier 107 is a bustling metropolis: thousands of stars in globular clusters like this one are concentrated into a space that is only about twenty times the distance between our Sun and its nearest stellar neighbour, Alpha Centauri, across. A significant number of these stars have already evolved into red giants, one of the last stages of a star's life, and have a yellowish colour in this image.

Globular clusters are among the oldest objects in the Universe. And since the stars within a globular cluster formed from the same cloud of interstellar matter at roughly the same time typically over 10 billion years ago they are all low-mass stars, as lightweights burn their hydrogen fuel supply much more slowly than stellar behemoths. Globular clusters formed during the earliest stages in the formation of their host galaxies and therefore studying these objects can give significant insights into how galaxies, and their component stars, evolve.

Messier 107 has undergone intensive observations, being one of the 160 stellar fields that was selected for the Pre-FLAMES Survey a preliminary survey conducted between 1999 and 2002 using the 2.2-metre telescope at ESO's La Silla Observatory in Chile, to find suitable stars for follow-up observations with the VLT's spectroscopic instrument FLAMES [1]. Using FLAMES, it is possible to observe up to 130 targets at the same time, making it especially well suited to the spectroscopic study of densely populated stellar fields, such as globular clusters......... Posted by: Sean      Read more         Source

November 11, 2010, 7:26 AM CT

Saturn Is on a Cosmic Dimmer Switch

Like a cosmic light bulb on a dimmer switch, Saturn emitted gradually less energy each year from 2005 to 2009, as per observations by NASA's Cassini spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere consistently emitted more energy than its northern one. On top of that, energy levels changed with the seasons and differed from the last time a spacecraft visited in the early part of 1980s. These never-before-seen trends came from an analysis of comprehensive data from the Composite Infrared Spectrometer (CIRS), an instrument built by NASA's Goddard Space Flight Center in Greenbelt, Md., as well as a comparison with earlier data from NASA's Voyager spacecraft. When combined with information about the energy coming to Saturn from the sun, the results could help researchers understand the nature of Saturn's internal heat source.

The findings were reported November 9 in the Journal of Geophysical Research-Planets by Liming Li of Cornell University in Ithaca, N.Y. (now at the University of Houston), and his colleagues from several institutions, including Goddard and NASA's Jet Propulsion Laboratory in Pasadena Calif., which manages the Cassini mission. "The Cassini CIRS data are very valuable because they give us a nearly complete picture of Saturn," says Li. "This is the only single data set that provides so much information about this planet, and it's the first time that anybody has been able to study the power emitted by one of the giant planets in such detail"......... Posted by: Sean      Read more         Source

November 8, 2010, 7:30 AM CT

Secrets of exploding plasma clouds on the sun

The Sun sporadically expels trillions of tons of million-degree hydrogen gas in explosions called coronal mass ejections (CMEs). Such cloudsan example is shown in Figure 1aare enormous in size (spanning millions of miles) and are made up of magnetized plasma gases, so hot that hydrogen atoms are ionized. CMEs are rapidly accelerated by magnetic forces to speeds of hundreds of kilometers per second to upwards of 2,000 kilometers per second in several tens of minutes. CMEs are closely correlation to solar flares and, when they impinge on the Earth, can trigger spectacular auroral displays. They also induce strong electric currents in the Earth's plasma atmosphere (i.e., the magnetosphere and ionosphere), leading to outages in telecommunications and GPS systems and even the collapse of electric power grids if the disturbances are very severe.

Since the first observation of a solar flare in 1859, solar eruptions ("explosions") have attracted much attention from researchers around the world and have been studied with a succession of increasingly sophisticated international satellite missions in the past three decades. A major challenge has been that enormous and complicated plasma structures accelerating away from the Sun can only be observed remotely. As a result, it has been difficult to test theoretical models to establish a correct understanding of the mechanisms that cause such eruptions. But in 2006, an international twin-satellite mission called STEREO was launched to continuously observe the erupting plasma structures from the Sun to the Earth......... Posted by: Sean      Read more         Source

November 5, 2010, 7:50 AM CT

Deep impact spacecraft flies by comet Hartley 2

The University of Maryland-led EPOXI mission successfully flew by comet Hartley 2 at 10 a.m. EDT today, and the spacecraft has begun returning images. Hartley 2 is the fifth comet nucleus visited by any spacecraft and the second one visited by the Deep Impact spacecraft.

Researchers and mission controllers are studying never-before-seen images of Hartley 2 appearing on their computer terminal screens. See images at: http://epoxi.umd.edu/.

"We are all holding our breath to see what discoveries await us in the observations near closest approach," said University of Maryland astronomer Michael A'Hearn, one of the originators of science team leader for both the Deep Impact mission and its follow on mission EPOXI.

At approximately 10 a.m. EDT, the spacecraft passed within 700 kilometers (435 miles) of the comet. Minutes after closest approach, the spacecraft's High-Gain Antenna was pointed at Earth and began downlinking vital spacecraft health and other engineering data stored aboard the spacecraft's onboard computer during the encounter. Twenty minutes later, the first images of the encounter made the 37 million kilometer (23 million mile) trip from the spacecraft to NASA's Deep Space Network antenna, appearing moments later on the mission's computer screens......... Posted by: Sean      Read more         Source

October 15, 2010, 6:49 AM CT

Into cosmic mysteries

An Ohio State University astronomer is working to unlock some of the mysteries surrounding the formation of vast galaxies and the evolution of massive black holes with his own large constellation of silicon wafers.

Over the last year, two research teams led by Stelios Kazantzidis, a Long-Term Fellow at the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University, have used what would average out to nearly 1,000 computing hours each day on the parallel high performance computing systems of the Ohio Supercomputer Center (OSC). To develop their detailed models and resulting simulations, Kazantzidis and colleagues tapped OSC's flagship system, the Glenn IBM Cluster 1350, which features more than 9,600 Opteron cores and 24 terabytes of memory.

Kazantzidis and University of Zurich student Simone Callegari recently authored a paper, "Growing Massive Black Hole Pairs in Minor Mergers of Disk Galaxies," and submitted it for publication in the Astrophysical Journal. Their study involved a suite of high-resolution, smoothed-particle hydrodynamics simulations of merging disk galaxies with supermassive black holes (SMBHs). These simulations include the effects of star formation and growth of the SMBHs, as well as feedback from both processes.

"Binary SMBHs are very important, because once they form there is always the possibility that the two black holes may subsequently merge," Kazantzidis explained. "Merging SMBHs will produce the strongest signal of gravitational wave emission in the universe. Gravitational waves have still not been directly detected, eventhough Einstein predicted them in his Theory of General Relativity"......... Posted by: Sean      Read more         Source