Ultra-Fast Outflows Help Monster Black Holes Shape Their Galaxies

A curious correlation between the mass of a galaxy's central black hole and the velocity of stars in a vast, roughly spherical structure known as its bulge has puzzled astronomers for years. An international team led by Francesco Tombesi at NASA's Goddard Space Flight Center in Greenbelt, Md., now has identified a new type of black-hole-driven outflow that appears to be both powerful enough and common enough to explain this link.

Most big galaxies contain a central black hole weighing millions of times the sun's mass, but galaxies hosting more massive black holes also possess bulges that contain, on average, faster-moving stars. This link suggested some sort of feedback mechanism between a galaxy's black hole and its star-formation processes. Yet there was no adequate explanation for how a monster black hole's activity, which strongly affects a region several times larger than our solar system, could influence a galaxy's bulge, which encompasses regions roughly a million times larger.

"This was a real conundrum. Everything was pointing to supermassive black holes as somehow driving this connection, but only now are we beginning to understand how they do it," Tombesi said.

Active black holes acquire their power by gradually accreting -- or "feeding" on -- million-degree gas stored in a vast surrounding disk. This hot disk lies within a corona of energetic particles, and while both are strong X-ray sources, this emission cannot account for galaxy-wide properties. Near the inner edge of the disk, a fraction of the matter orbiting a black hole often is redirected into an outward particle jet. Although these jets can hurl matter at half the speed of light, computer simulations show that they remain narrow and deposit most of their energy far beyond the galaxy's star-forming regions.

Astronomers suspected they were missing something. Over the last decade, evidence for a new type of black-hole-driven outflow has emerged. At the centers of some active galaxies, X-ray observations at wavelengths corresponding to those of fluorescent iron show that this radiation is being absorbed. This means that clouds of cooler gas must lie in front of the X-ray source. What's more, these absorbed spectral lines are displaced from their normal positions to shorter wavelengths -- that is, blueshifted, which indicates that the clouds are moving toward us.

In two previously published studies, Tombesi and his colleagues showed that these clouds represented a distinct type of outflow. In the latest study, which appears in the Feb. 27 issue of Monthly Notices of the Royal Astronomical Society, the researchers targeted 42 nearby active galaxies using the European Space Agency's XMM-Newton satellite to hone in on the location and properties of these so-called "ultra-fast outflows" -- or UFOs, for short. The galaxies, which were selected from the All-Sky Slew Survey Catalog produced by NASA's Rossi X-ray Timing Explorer satellite, were all located less than 1.3 billion light-years away.

The outflows turned up in 40 percent of the sample, which suggests that they're common features of black-hole-powered galaxies. On average, the distance between the clouds and the central black hole is less than one-tenth of a light-year. Their average velocity is about 14 percent the speed of light, or about 94 million mph, and the team estimates that the amount of matter required to sustain the outflow is close to one solar mass per year -- comparable to the accretion rate of these black holes.

"Although slower than particle jets, UFOs possess much faster speeds than other types of galactic outflows, which makes them much more powerful," Tombesi explained.

"They have the potential to play a major role in transmitting feedback effects from a black hole into the galaxy at large."

By removing mass that would otherwise fall into a supermassive black hole, ultra-fast outflows may put the brakes on its growth. At the same time, UFOs may strip gas from star-forming regions in the galaxy's bulge, slowing or even shutting down star formation there by sweeping away the gas clouds that represent the raw material for new stars. Such a scenario would naturally explain the observed connection between an active galaxy's black hole and its bulge stars.

Tombesi and his team anticipate significant improvement in understanding the role of ultra-fast outflows with the launch of the Japan-led Astro-H X-ray telescope, currently scheduled for 2014. In the meantime, he intends to focus on determining the detailed physical mechanisms that give rise to UFOs, an important element in understanding the bigger picture of how active galaxies form, develop and grow.

Dwarf Galaxy Questions Current Galaxy Formation Models

Researcher from the Centro de Astrofísica da Universidade do Porto (Center for Astrophysics of the University of Porto) observed the dwarf galaxy I Zw 18, and found that much of what is known about galaxy formation and evolution might need substantial revision.

CAUP Astronomer Polychronis Papaderos, along with his colleague Göran Östlin (Oskar Klein Center, U. Stokholm), used the Hubble Space Telescope (HST) to get extremely accurate observations of the I Zw 18 galaxy. Their research led to the conclusion that this enigmatic blue compact dwarf might force astronomers to review current galaxy formation models.

I Zw 18 is one of the most studied dwarf galaxies, because among those that have strong star forming activity, it's one of the poorest in heavy elements. Besides, it's proximity to Earth, combined with a total exposure time of nearly 3 days, gave the researchers data with unprecedented resolution and sensitivity.

Analysis of these data revealed an extended gas halo surrounding this galaxy, 16 times larger than the star component of the galaxy, and without any stars. This halo is the result of huge amounts of energy generated by the starburst this galaxy is going through. This energy heats and disturbs I Zw 18's cold gas, which ends up emitting an amount of light comparable to what's being emitted by the stellar component. This emission is designated nebular emission.

Papaderos, a greek astronomer working in Portugal, comments that: "This is ground-breaking work because it provides the first observational proof that, in the early Universe, young galaxies that underwent starbursts must have been surrounded by a huge halo of nebular emission. This extended nebular halo results from the cumulative energetic output from thousands of massive stars exploding as supernovae, shortly after their formation."

So far, in distant galaxies where it's not possible to reach resolutions high enough in order to distinguish between nebular and star emission, it was assumed that the gas occupied the same region as the stars and stars were responsible for emitting most of the light.

This study showed that galaxies undergoing starbursts, similar to I Zw 18, might not obey this rule. This result might lead to substantial corrections in a lot of the work being developed in cosmology and extragalactic astronomy. An example is the estimate of star mass in a galaxy, which is calculated from the galaxies total luminosity. But, as these results shows, up to 50% of that luminosity might originate in nebular, and not star, emission.

Another result from this research shows that, according to Papaderos, "the distribution of nebular emission might be misinterpreted as a stellar disk. These galaxies, still in early stages of formation, might thus be wrongly classified as fully formed galaxies" (such as spirals or ellipticals), a classification mistake that might have happened in many past studies to determine galaxy evolution in the early Universe.

These results are also of importance for our understanding of galaxy formation, because the team concluded that I Zw 18 is extremely young, with most stars younger than 1 billion years. So this galaxy is currently undergoing the dominant phase of its formation, much like the ones formed shortly after the Big Bang.

The Many Moods of Titan

A set of recent papers, many of which draw on data from NASA's Cassini spacecraft, reveal new details in the emerging picture of how Saturn's moon Titan shifts with the seasons and even throughout the day. The papers, published in the journal Planetary and Space Science in a special issue titled "Titan through Time," show how this largest moon of Saturn is a cousin -- though a very peculiar cousin -- of Earth.

"As a whole, these papers give us some new pieces in the jigsaw puzzle that is Titan," said Conor Nixon, a Cassini team scientist at the NASA Goddard Space Flight Center, Greenbelt, Md., who co-edited the special issue with Ralph Lorenz, a Cassini team scientist based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. "They show us in detail how Titan's atmosphere and surface behave like Earth's -- with clouds, rainfall, river valleys and lakes. They show us that the seasons change, too, on Titan, although in unexpected ways."

A paper led by Stephane Le Mouelic, a Cassini team associate at the French National Center for Scientific Research (CNRS) at the University of Nantes, highlights the kind of seasonal changes that occur at Titan with a set of the best looks yet at the vast north polar cloud.

A newly published selection of images -- made from data collected by Cassini's visual and infrared mapping spectrometer over five years -- shows how the cloud thinned out and retreated as winter turned to spring in the northern hemisphere.

Cassini first detected the cloud, which scientists think is composed of ethane, shortly after its arrival in the Saturn system in 2004. The first really good opportunity for the spectrometer to observe the half-lit north pole occurred on December 2006. At that time, the cloud appeared to cover the north pole completely down to about 55 degrees north latitude. But in the 2009 images, the cloud cover had so many gaps it unveiled to Cassini's view the hydrocarbon sea known as Kraken Mare and surrounding lakes.

"Snapshot by snapshot, these images give Cassini scientists concrete evidence that Titan's atmosphere changes with the seasons," said Le Mouelic. "We can't wait to see more of the surface, in particular in the northern land of lakes and seas."

In data gathered by Cassini's composite infrared mapping spectrometer to analyze temperatures on Titan's surface, not only did scientists see seasonal change on Titan, but they also saw day-to-night surface temperature changes for the first time. The paper, led by Valeria Cottini, a Cassini associate based at Goddard, used data collected at a wavelength that penetrated through Titan's thick haze to see the moon's surface. Like Earth, the surface temperature of Titan, which is usually in the chilly mid-90 kelvins (around minus 288 degrees Fahrenheit), was significantly warmer in the late afternoon than around dawn.

"While the temperature difference -- 1.5 kelvins -- is smaller than what we're used to on Earth, the finding still shows that Titan's surface behaves in ways familiar to us earthlings," Cottini said. "We now see how the long Titan day (about 16 Earth days) reveals itself through the clouds."

A third paper by Dominic Fortes, an outside researcher based at University College London, England, addresses the long-standing mystery of the structure of Titan's interior and its relationship to the strikingly Earth-like range of geologic features seen on the surface. Fortes constructed an array of models of Titan's interior and compared these with newly acquired data from Cassini's radio science experiment.

The work shows the moon's interior is partly or possibly even fully differentiated. This means that the core is denser than outer parts of the moon, although less dense than expected. This may be because the core still contains a large amount of ice or because the rocks have reacted with water to form low-density minerals.

Earth and other terrestrial planets are fully differentiated and have a dense iron core. Fortes' model, however, rules out a metallic core inside Titan and agrees with Cassini magnetometer data that suggests a relatively cool and wet rocky interior. The new model also highlights the difficulty in explaining the presence of important gases in Titan's atmosphere, such as methane and argon-40, since they do not appear to be able to escape from the core.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate, Washington, D.C. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center in Greenbelt, Md., where the instrument was built. The radio science subsystem has been jointly developed by NASA and the Italian Space Agency.

Chemical Clues On Formation of Planetary Systems: Earth 'Siblings' Can Be Different

An international team of researchers, with the participation of IAC astronomers, has discovered that the chemical structure of Earth-like planets can be very different from the bulk composition of Earth. This may have a dramatic effect on the existence and formation of the biospheres and life on Earth-like planets.

The study of the photospheric stellar abundances of the planet-host stars is the key to understanding how protoplanets form, as well as which protoplanetary clouds evolve planets and which do not. These studies, which have important implications for models of giant planet formation and evolution, also help us to investigate the internal and atmospheric structure and composition of extrasolar planets..
Theoretical studies suggest that C/O and Mg/Si, are the most important elemental ratios in determining the mineralogy of terrestrial planets, and they can give us information about the composition of these planets. The C/O ratio controls the distribution of Si among carbide and oxide species, while Mg/Si gives information on the silicate mineralogy. In 2010 Bond et al. (2010b) carried out the first numerical simulations of planet formation in which the chemical composition of the proto-planetary cloud was taken as an input parameter. Terrestrial planets were found to form in all the simulations with a wide variety of chemical compositions so these planets might be very different from Earth.
Delgado Mena et al. (2010) have carried out the first detailed and uniform study of C, O, Mg and Si abundances for 61 stars with detected planets and 270 stars without detected planets from the homogeneous high-quality unbiased HARPS GTO sample. They found mineralogical ratios quite different from those in the Sun, showing that there is a wide variety of planetary systems which are unlike the Solar System. Many planetary-host stars present a Mg/Si value lower than 1, so their planets will have a high Si content to form species such as MgSiO3. This type of composition can have important implications for planetary processes like plate tectonics, atmospheric composition and volcanism.
'There could be billions of Earth-like planets in the Universe but a great majority of them may have a totally different internal and atmospheric structure. Building planets in chemically non-solar environments (which are very common in the Universe) may lead to the formation of strange worlds, very different from the Earth! The amount of radioactive and some refractory elements (especially Si) may have drastic implications for planetary processes such as plate tectonics and volcanic activity,' concludes Garik Israelian.
The latest numerical simulations have shown that a wide range of extrasolar terrestrial planet bulk compositions are likely to exist. Planets simulated as forming around stars with Mg/Si ratios less than 1 are found to be Mg-depleted (compared to Earth), consisting of silicate species such as pyroxene and various types of feldspars. Planetary carbon abundances also vary in accordance with the host stars' C/O ratio. The predicted abundances are in keeping with observations of polluted white dwarfs (expected to have accreted their inner planets during their previous red giant stage).
'The observed variations in the key C/O and Mg/Si ratios for known planetary host stars implies that a wide variety of extrasolar terrestrial planet compositions are likely to exist, ranging from relatively "Earth-like" planets to those that are dominated by C, such as graphite and carbide phases (e.g. SiC, TiC),' Delgado Mena stresses.
The results of Delgado Mena et al. (2010) were used in this study as they are the first to determine the abundance of all of the required elements in a completely internally consistent manner, using high quality spectra and an identical approach for all stars and elements, for a large sample of both host and non-host stars.
The chemical and dynamical simulations were combined by assuming that each embryo retains the composition of its formation location and contributes the same composition to the simulated terrestrial planet. The innermost terrestrial planets (located within ?0.5 AU from the host star) contain a significant amount of the refractory elements Al and Ca (?47% of the planetary mass). Planets forming beyond ?0.5 AU from the host star contain steadily less Al and Ca with increasing distance. One planetary system, 55 Cnc, has a C/O ratio above 1 (C/O = 1.12). This system produced carbon-enriched "Earth-like" planets. All of the terrestrial planets considered in this work have compositions dominated by O, Fe, Mg and Si, most of these elements being delivered in the form of silicates or metals (in the case of iron). However, important differences between those planets forming in systems with C/O < 0.8 (HD17051, HD19994) and those with C/O > 0.8 (55Cnc) have been found.
'We are working hard to decrease abundance measurement errors and make the results of theoretical models and numerical simulations more reliable,' comments González Hernández, 'There is much work to be done'.

Black Hole Came from a Shredded Galaxy

Astronomers using NASA's Hubble Space Telescope have found a cluster of young, blue stars encircling the first intermediate-mass black hole ever discovered. The presence of the star cluster suggests that the black hole was once at the core of a now-disintegrated dwarf galaxy. The discovery of the black hole and the star cluster has important implications for understanding the evolution of supermassive black holes and galaxies.


"For the first time, we have evidence on the environment, and thus the origin, of this middle-weight black hole," said Mathieu Servillat, who worked at the Harvard-Smithsonian Center for Astrophysics when this research was conducted.
Astronomers know how massive stars collapse to form stellar-mass black holes (which weigh about 10 times the mass of our sun), but it's not clear how supermassive black holes (like the four million solar-mass monster at the center of the Milky Way) form in the cores of galaxies. One idea is that supermassive black holes may build up through the merger of smaller, intermediate-mass black holes weighing hundreds to thousands of suns.
Lead author Sean Farrell, of the Sydney Institute for Astronomy in Australia, discovered this unusual black hole in 2009 using the European Space Agency's XMM-Newton X-ray space telescope. Known as HLX-1 (Hyper-Luminous X-ray source 1), the black hole weighs in at 20,000 solar masses and lies towards the edge of the galaxy ESO 243-49, which is 290 million light-years from Earth.
Farrell and his team then observed HLX-1 simultaneously with NASA's Swift observatory in X-ray and Hubble in near-infrared, optical, and ultraviolet wavelengths. The intensity and the color of the light shows a cluster of young stars, 250 light-years across, encircling the black hole. Hubble can't resolve the stars individually because the suspected cluster is too far away. The brightness and color are consistent with other clusters of young stars seen in other galaxies.
Farrell's team detected blue light from hot gas in the accretion disk swirling around the black hole. However, they also detected red light produced by much cooler gas, which would most likely come from stars. Computer models suggested the presence of a young, massive cluster of stars encircling the black hole.
"What we can definitely say with our Hubble data is that we require both emission from an accretion disk and emission from a stellar population to explain the colors we see," said Farrell.
Such young clusters of stars are commonly seen in nearby galaxies, but not outside the flattened starry disk, as found with HLX-1. The best explanation is that the HLX-1 black hole was the central black hole in a dwarf galaxy. The larger host galaxy then captured the dwarf. Most of the dwarf's stars were stripped away through the collision between the galaxies. At the same time, new young stars were formed in the encounter. The interaction that compressed the gas around the black hole also triggered star formation.
Farrell and Servillat found that the star cluster must be less than 200 million years old. This means that the bulk of the stars were formed following the dwarf's collision with the larger galaxy. The age of the stars tells how long ago the two galaxies crashed into each other.
The future of the black hole is uncertain at this stage. It depends on its trajectory, which is currently unknown. It's possible the black hole may spiral in to the center of the big galaxy and eventually merge with the supermassive black hole there. Alternately, the black hole could settle into a stable orbit around the galaxy. Either way, it's likely to fade away in X-rays as it depletes its supply of gas.
"This black hole is unique in that it's the only intermediate-mass black hole we've found so far. Its rarity suggests that these black holes are only visible for a short time," said Servillat.
More observations are planned this year to track the history of the interaction between the two galaxies.
The new findings are being published in the February 15 issue of the Astrophysical Journal Letters.

Great Eruption Replay: Astronomers Watch Delayed Broadcast of Powerful Stellar Eruption

Astronomers are watching a delayed broadcast of a spectacular outburst from the unstable, behemoth double-star system Eta Carinae, an event initially seen on Earth nearly 170 years ago.




Dubbed the "Great Eruption," the outburst first caught the attention of sky watchers in 1837 and was observed through 1858. But astronomers didn't have sophisticated science instruments to accurately record the star system's petulant activity.
Luckily for today's astronomers, some of the light from the eruption took an indirect path to Earth and is just arriving now, providing an opportunity to analyze the outburst in detail. The wayward light was heading in a different direction, away from our planet, when it bounced off dust clouds lingering far from the turbulent stars and was rerouted to Earth, an effect called a "light echo." Because of its longer path, the light reached Earth 170 years later than the light that arrived directly.
The observations of Eta Carinae's light echo are providing new insight into the behavior of powerful massive stars on the brink of detonation. The views of the nearby erupting star reveal some unexpected results, which will force astronomers to modify physical models of the outburst.
"When the eruption was seen on Earth 170 years ago, there were no cameras capable of recording the event," explained the study's leader, Armin Rest of the Space Telescope Science Institute in Baltimore, Md. "Everything astronomers have known to date about Eta Carinae's outburst is from eyewitness accounts. Modern observations with science instruments were made years after the eruption actually happened. It's as if nature has left behind a surveillance tape of the event, which we are now just beginning to watch. We can trace it year by year to see how the outburst changed."
The team's paper will appear Feb. 16 in a letter to the journalNature.
Located 7,500 light-years from Earth, Eta Carinae is one of the largest and brightest star systems in our Milky Way galaxy. Although the chaotic duo is known for its petulant outbursts, the Great Eruption was the biggest ever observed. During the 20-year episode, Eta Carinae shed some 20 solar masses and became the second brightest star in the sky. Some of the outflow formed the system's twin giant lobes. Before the epic event, the stellar pair was 140 times heftier than our Sun.
Because Eta Carinae is relatively nearby, astronomers have used a variety of telescopes, including the Hubble Space Telescope, to document its escapades. The team's study involved a mix of visible-light and spectroscopic observations from ground-based telescopes.
The observations mark the first time astronomers have used spectroscopy to analyze a light echo from a star undergoing powerful recurring eruptions, though they have measured this unique phenomenon around exploding stars called supernovae. Spectroscopy captures a star's "fingerprints," providing details about its behavior, including the temperature and speed of the ejected material.
The delayed broadcast is giving astronomers a unique look at the outburst and turning up some surprises. The turbulent star system does not behave like other stars of its class. Eta Carinae is a member of a stellar class called Luminous Blue Variables, large, extremely bright stars that are prone to periodic outbursts. The temperature of the outflow from Eta Carinae's central region, for example, is about 8,500 degrees Fahrenheit (5,000 Kelvin), which is much cooler than that of other erupting stars. "This star really seems to be an oddball," Rest said. "Now we have to go back to the models and see what has to change to actually produce what we are measuring."
Rest's team first spotted the light echo while comparing visible-light observations he took of the stellar duo in 2010 and 2011 with the U.S. National Optical Astronomy Observatory's Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. He obtained another set of CTIO observations taken in 2003 by astronomer Nathan Smith of the University of Arizona in Tucson, which helped him piece together the whole 20-year outburst.
The images revealed light that seemed to dart through and illuminate a canyon of dust surrounding the doomed star system. "I was jumping up and down when I saw the light echo," said Rest, who has studied light echoes from powerful supernova blasts. "I didn't expect to see Eta Carinae's light echo because the eruption was so much fainter than a supernova explosion. We knew it probably wasn't material moving through space. To see something this close move across space would take decades of observations. We, however, saw the movement over a year's time. That's why we thought it was probably a light echo."
Although the light in the images appears to move over time, it's really an optical illusion. Each flash of light is reaching Earth at a different time, like a person's voice echoing off the walls of a canyon.
The team followed up its study with spectroscopic observations, using the Carnegie Institution of Washington's Magellan and du Pont telescopes at Las Campanas Observatory in Chile. That study helped the astronomers decode the light, revealing the outflow's speed and temperature. The observations showed that ejected material was moving at roughly 445,000 miles an hour (more than 700,000 kilometers an hour), which matches predictions.
Rest's group monitored changes in the intensity of the light echo using the Las Cumbres Observatory Global Telescope Network's Faulkes Telescope South in Siding Spring, Australia. The team then compared those measurements with a plot astronomers in the 1800s made of the light brightening and dimming over the course of the 20-year eruption. The new measurements matched the signature of the 1843 peak in brightness.
The team will continue to follow Eta Carinae because light from the outburst is still streaming to Earth. "We should see brightening again in six months from another increase in light that was seen in 1844," Rest said. "We hope to capture light from the outburst coming from different directions so that we can get a complete picture of the eruption."
Rest's team consists of J.L. Prieto, Carnegie Observatories, Pasadena, Calif.; N.R. Walborn and H.E. Bond, Space Telescope Science Institute, Baltimore, Md.; N. Smith, Steward Observatory, University of Arizona, Tucson; F.B. Bianco and D.A. Howell, Las Cumbres Observatory Global Telescope Network, Goleta, Calif., and University of California, Santa Barbara; R. Chornock, R.J. Foley, and W. Fong, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.; D.L. Welch and B. Sinnott, McMaster University, Hamilton, Ontario; M.E. Huber, Johns Hopkins University, Baltimore, Md.; R.C. Smith, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, La Serena, Chile; I. Toledo, Atacama Large Millimeter Array (ALMA), Chile; D. Minniti, Pontifica Universidad Catolica, Santiago, Chile; and K. Mandel, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., and Imperial College London, U.K.

Plasmas Torn Apart: Discovery Hints at Origin of Phenomena Like Solar Flares

January saw the biggest solar storm since 2005, generating some of the most dazzling northern lights in recent memory.


he source of that storm -- and others like it -- was the sun's magnetic field, described by invisible field lines that protrude from and loop back into the burning ball of gas. Sometimes these field lines break -- snapping like a rubber band pulled too tight -- and join with other nearby lines, releasing energy that can then launch bursts of plasma known as solar flares. Huge chunks of plasma from the sun's surface can zip toward Earth and damage orbiting satellites or bump them off their paths.
These chunks of plasma, called coronal mass ejections, can also snap Earth's magnetic field lines, causing charged particles to speed toward Earth's magnetic poles; this, in turn, sets off the shimmering light shows we know as the northern and southern lights.
Even though the process of field lines breaking and merging with other lines -- called magnetic reconnection -- has such significant effects, a detailed picture of what precisely is going on has long eluded scientists, says Paul Bellan, professor of applied physics in the Division of Engineering and Applied Science at the California Institute of Technology (Caltech).
Now, using high-speed cameras to look at jets of plasma in the lab, Bellan and graduate student Auna Moser have discovered a surprising phenomenon that provides clues to just how magnetic reconnection occurs. They describe their results in a paper published in the February 16 issue of the journal Nature.
"Trying to understand nature by using engineering techniques is indeed a hallmark of the Division of Engineering and Applied Science at Caltech," says Ares Rosakis, the Theodore von Kármán Professor of Aeronautics and professor of mechanical engineering and the chair of engineering and applied science.
In the experiments, Moser fired jets of hydrogen, nitrogen, and argon plasmas at speeds of about 10 to 50 kilometers per second across a distance of more than 20 centimeters in a vacuum. Plasma is a gas so hot that atoms are stripped of their electrons. As a throughway for speeding electrons, the jets act like electrical wires. The experiment requires 200 million watts of power to produce jets that are a scorching 20,000 degrees Kelvin and carry a current of 100,000 amps. To study the jets, Moser used cameras that can take a snapshot in less than a microsecond, or one millionth of a second.
As in all electrical currents, the flowing electrons in the plasma jet generate a magnetic field, which then exerts a force on the plasma. These electromagnetic interactions between the magnetic field and the plasma can cause the jet to writhe and form a rapidly expanding corkscrew. This behavior, called a kink instability, has been studied for nearly 60 years, Bellan says.
But when Moser looked closely at this behavior in her experimental plasma jets, she saw something entirely unexpected.
She found that -- more often than not -- the corkscrew shape that developed in her jets grew exponentially and extremely fast. The jets in the experiment formed 20-centimeter-long coils in just 20 to 25 microseconds. She also noticed tiny ripples that began appearing on the inner edge of the coil just before the jet broke -- the moment when there was a magnetic reconnection.
In the beginning, Moser and Bellan say, they did not know what they were seeing -- they just knew it was strange. "I thought it was a measurement error," Bellan says. "But it was way too reproducible. We were seeing it day in and day out. At first, I thought we would never figure it out."
But after months of additional experiments, they determined that the kink instability actually spawns a completely different kind of phenomenon, called a Rayleigh-Taylor instability. A Rayleigh-Taylor instability happens when a heavy fluid that sits on top of a light fluid tries to trade places with the light fluid. Ripples form and grow at the interface between the two, allowing the fluids to swap places.
What Moser and Bellan realized is that the kink instability creates conditions that give rise to a Rayleigh-Taylor instability. As the coiled plasma expands -- due to the kink instability -- it accelerates outward. Just like a passenger being pushed back into the seat of an accelerating car, the accelerated plasma is pushed down on the vacuum behind it. The plasma tries to swap places with the trailing vacuum by forming ripples that then expand -- just like when gravity forces a heavy fluid to try to change places with a light fluid underneath. The Rayleigh-Taylor instability -- as revealed by the ripples on the trailing side of the accelerating plasma -- grows in about a microsecond.
"People have not observed anything like this before," Bellan says.
Although the Rayleigh-Taylor instability has been studied for more than 100 years, no one had considered the possibility that it could be caused by a kink instability, Bellan says. The two types of instabilities are so different that to see them so closely coupled was a shock. "Nobody ever thought there was a connection," he says.
What is notable is that the two instabilities occur at very different scales, the researchers say. While the coil created by the kink instability spans about 20 centimeters, the Rayleigh-Taylor instability is much smaller, making ripples just two centimeters long. Still, those smaller ripples rapidly erode the jet, forcing the electrons to flow faster and faster through a narrowing channel. "You're basically choking it off," Bellan explains. Soon, the jet breaks, causing a magnetic reconnection.
Magnetic reconnection on the sun often involves phenomena that span scales from a million meters to just a few meters. At the larger scales, the physics is relatively simple and straightforward. But at the smaller scales, the physics becomes more subtle and complex -- and it is in this regime that magnetic reconnection takes place. Magnetic reconnection is also a key issue in developing thermonuclear fusion as a future energy source using plasmas in the laboratory. One of the key advances in this study, the researchers say, is being able to relate phenomena at large scales, such as the kink instability, to those at small scales, such as the Rayleigh-Taylor instability.
The researchers note that, although kink and Rayleigh-Taylor instabilities may not drive magnetic reconnection in all cases, this mechanism is a plausible explanation for at least some scenarios in nature and the lab.
The title of Moser and Bellan's Nature paper is "Magnetic reconnection from a multiscale instability cascade." This research was funded by the U.S. Department of Energy, the National Science Foundation, and the Air Force Office of Scientific Research.

Newborn Stars Emerge from Dark Clouds in Taurus

A new image from the APEX (Atacama Pathfinder Experiment) telescope in Chile shows a sinuous filament of cosmic dust more than ten light-years long. In it, newborn stars are hidden, and dense clouds of gas are on the verge of collapsing to form yet more stars. It is one of the regions of star formation closest to us. The cosmic dust grains are so cold that observations at wavelengths of around one millimetre, such as these made with the LABOCA camera on APEX, are needed to detect their faint glow.


The Taurus Molecular Cloud, in the constellation of Taurus (The Bull), lies about 450 light-years from Earth. This image shows two parts of a long, filamentary structure in this cloud, which are known as Barnard 211 and Barnard 213. Their names come from Edward Emerson Barnard's photographic atlas of the "dark markings of the sky," compiled in the early 20th century. In visible light, these regions appear as dark lanes, lacking in stars. Barnard correctly argued that this appearance was due to "obscuring matter in space."
We know today that these dark markings are actually clouds of interstellar gas and dust grains. The dust grains -- tiny particles similar to very fine soot and sand -- absorb visible light, blocking our view of the rich star field behind the clouds. The Taurus Molecular Cloud is particularly dark at visible wavelengths, as it lacks the massive stars that illuminate the nebulae in other star-formation regions such as Orion. The dust grains themselves also emit a faint heat glow but, as they are extremely cold at around -260 degrees Celsius, their light can only be seen at wavelengths much longer than visible light, around one millimetre.
These clouds of gas and dust are not merely an obstacle for astronomers wishing to observe the stars behind them. In fact, they are themselves the birthplaces of new stars. When the clouds collapse under their own gravity, they fragment into clumps. Within these clumps, dense cores may form, in which the hydrogen gas becomes dense and hot enough to start fusion reactions: a new star is born. The birth of the star is therefore surrounded by a cocoon of dense dust, blocking observations at visible wavelengths. This is why observations at longer wavelengths, such as the millimetre range, are essential for understanding the early stages of star formation.
The upper-right part of the filament shown here is Barnard 211, while the lower-left part is Barnard 213. The millimetre-range observations from the LABOCA camera on APEX, which reveal the heat glow of the cosmic dust grains, are shown here in orange tones, and are superimposed on a visible light image of the region, which shows the rich background of stars. The bright star above the filament is φ Tauri, while the one partially visible at the left-hand edge of the image is HD 27482. Both stars are closer to us than the filament, and are not associated with it.
Observations show that Barnard 213 has already fragmented and formed dense cores -- as illustrated by the bright knots of glowing dust -- and star formation has already happened. However, Barnard 211 is in an earlier stage of its evolution; the collapse and fragmentation is still taking place, and will lead to star formation in the future. This region is therefore an excellent place for astronomers to study how Barnard's "dark markings of the sky" play a crucial part in the lifecycle of stars.
The observations were made by Alvaro Hacar (Observatorio Astronómico Nacional-IGN, Madrid, Spain) and collaborators. The LABOCA camera operates on the 12-metre APEX telescope, on the plateau of Chajnantor in the Chilean Andes, at an altitude of 5000 metres. APEX is a pathfinder for the next generation submillimetre telescope, the Atacama Large Millimeter/submillimeter Array (ALMA), which is being built and operated on the same plateau.

Globular Clusters: Survivors of a 13-Billion-Year-Old Massacre

Our Milky Way galaxy is surrounded by some 200 compact groups of stars, containing up to a million stars each. At 13 billion years of age, these globular clusters are almost as old as the universe itself and were born when the first generations of stars and galaxies formed. Now a team of astronomers from Germany and the Netherlands have conducted a novel type of computer simulation that looked at how they were born -- and they find that these giant clusters of stars are the only survivors of a 13-billion-year-old massacre that destroyed many of their smaller siblings.
The new work, led by Dr Diederik Kruijssen of the Max Planck Institute for Astrophysics in Garching, Germany, appears in a paper in the journal Monthly Notices of the Royal Astronomical Society.
Globular star clusters have a remarkable characteristic: the typical number of stars they contain appears to be about the same throughout the Universe. This is in contrast to much younger stellar clusters, which can contain almost any number of stars, from fewer than 100 to many thousands. The team of scientists proposes that this difference can be explained by the conditions under which globular clusters formed early on in the evolution of their host galaxies.
The researchers ran simulations of isolated and colliding galaxies, in which they included a model for the formation and destruction of stellar clusters. When galaxies collide, they often generate spectacular bursts of star formation (“starbursts”) and a wealth of bright, young stellar clusters of many different sizes. As a result it was always thought that the total number of star clusters increases during starbursts. But the Dutch-German team found the opposite result in their simulations.
While the very brightest and largest clusters were indeed capable of surviving the galaxy collision due to their own gravitational attraction, the numerous smaller clusters were effectively destroyed by the rapidly changing gravitational forces that typically occur during starbursts due to the movement of gas, dust and stars. The wave of starbursts came to an end after about 2 billion years and the researchers were surprised to see that only clusters with high numbers of stars had survived. These clusters had all the characteristics that should be expected for a young population of globular clusters as they would have looked about 11 billion years ago.
Dr Kruijssen comments: “It is ironic to see that starbursts may produce many young stellar clusters, but at the same time also destroy the majority of them. This occurs not only in galaxy collisions, but should be expected in any starburst environment. In the early Universe, starbursts were commonplace – it therefore makes perfect sense that all globular clusters have approximately the same large number of stars. Their smaller brothers and sisters that didn’t contain as many stars were doomed to be destroyed.”
According to the simulations, most of the star clusters were destroyed shortly after their formation, when the galactic environment was still very hostile to the young clusters. After this episode ended, the surviving globular clusters have lived quietly until the present day.
The researchers have further suggestions to test their ideas. Dr Kruijssen continues: “In the nearby Universe, there are several examples of galaxies that have recently undergone large bursts of star formation. It should therefore be possible to see the rapid destruction of small stellar clusters in action. If this is indeed found by new observations, it will confirm our theory for the origin of globular clusters.”
The simulations suggest that most of a globular cluster’s traits were established when it formed. The fact that globular clusters are comparable everywhere then indicates that the environments in which they formed were very similar, regardless of the galaxy they currently reside in. In that case, Dr Kruijssen believes, they can be used as fossils to shed more light on the conditions in which the first stars and galaxies were born.

The above story is reprinted from materials provided by Royal Astronomical Society (RAS), via AlphaGalileo.

NASA's Chandra Finds Milky Way's Black Hole Grazing on Asteroids

 The giant black hole at the center of the Milky Way may be vaporizing and devouring asteroids, which could explain the frequent flares observed, according to astronomers using data from NASA's Chandra X-ray Observatory.

For several years Chandra has detected X-ray flares about once a day from the supermassive black hole known as Sagittarius A*, or "Sgr A*" for short. The flares last a few hours with brightness ranging from a few times to nearly one hundred times that of the black hole's regular output. The flares also have been seen in infrared data from ESO's Very Large Telescope in Chile.

"People have had doubts about whether asteroids could form at all in the harsh environment near a supermassive black hole," said Kastytis Zubovas of the University of Leicester in the United Kingdom, and lead author of the report appearing in the Monthly Notices of the Royal Astronomical Society. "It's exciting because our study suggests that a huge number of them are needed to produce these flares."

Zubovas and his colleagues suggest there is a cloud around Sgr A* containing trillions of asteroids and comets, stripped from their parent stars. Asteroids passing within about 100 million miles of the black hole, roughly the distance between the Earth and the sun, would be torn into pieces by the tidal forces from the black hole.

These fragments then would be vaporized by friction as they pass through the hot, thin gas flowing onto Sgr A*, similar to a meteor heating up and glowing as it falls through Earth's atmosphere. A flare is produced and the remains of the asteroid are swallowed eventually by the black hole.

"An asteroid's orbit can change if it ventures too close to a star or planet near Sgr A*," said co-author Sergei Nayakshin, also of the University of Leicester. "If it's thrown toward the black hole, it's doomed."

The authors estimate that it would take asteroids larger than about six miles in radius to generate the flares observed by Chandra. Meanwhile, Sgr A* also may be consuming smaller asteroids, but these would be difficult to spot because the flares they generate would be fainter.

These results reasonably agree with models estimating of how many asteroids are likely to be in this region, assuming that the number around stars near Earth is similar to the number surrounding stars near the center of the Milky Way.

"As a reality check, we worked out that a few trillion asteroids should have been removed by the black hole over the 10-billion-year lifetime of the galaxy," said co-author Sera Markoff of the University of Amsterdam in the Netherlands. "Only a small fraction of the total would have been consumed, so the supply of asteroids would hardly be depleted."

Planets thrown into orbits too close to Sgr A* also should be disrupted by tidal forces, although this would happen much less frequently than the disruption of asteroids, because planets are not as common. Such a scenario may have been responsible for a previous X-ray brightening of Sgr A* by about a factor of a million about a century ago. While this event happened many decades before X-ray telescopes existed, Chandra and other X-ray missions have seen evidence of an X-ray "light echo" reflecting off nearby clouds, providing a measure of the brightness and timing of the flare.

"This would be a sudden end to the planet's life, a much more dramatic fate than the planets in our solar system ever will experience," Zubovas said.

Very long observations of Sgr A* will be made with Chandra later in 2012 that will give valuable new information about the frequency and brightness of flares and should help to test the model proposed here to explain them. This work could improve understanding about the formation of asteroids and planets in the harsh environment of Sgr A*.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For Chandra images, multimedia and related materials, visit:

http://www.nasa.gov/chandra

For an additional interactive image, podcast, and video on the finding, visit:

http://chandra.si.edu

NASA Mission Takes Stock of Earth's Melting Land Ice

In the first comprehensive satellite study of its kind, a University of Colorado at Boulder-led team used NASA data to calculate how much Earth's melting land ice is adding to global sea level rise.

Using satellite measurements from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE), the researchers measured ice loss in all of Earth's land ice between 2003 and 2010, with particular emphasis on glaciers and ice caps outside of Greenland and Antarctica.

The total global ice mass lost from Greenland, Antarctica and Earth's glaciers and ice caps during the study period was about 4.3 trillion tons (1,000 cubic miles), adding about 0.5 inches (12 millimeters) to global sea level. That's enough ice to cover the United States 1.5 feet (0.5 meters) deep.

"Earth is losing a huge amount of ice to the ocean annually, and these new results will help us answer important questions in terms of both sea rise and how the planet's cold regions are responding to global change," said University of Colorado Boulder physics professor John Wahr, who helped lead the study. "The strength of GRACE is it sees all the mass in the system, even though its resolution is not high enough to allow us to determine separate contributions from each individual glacier."

About a quarter of the average annual ice loss came from glaciers and ice caps outside of Greenland and Antarctica (roughly 148 billion tons, or 39 cubic miles). Ice loss from Greenland and Antarctica and their peripheral ice caps and glaciers averaged 385 billion tons (100 cubic miles) a year. Results of the study will be published online Feb. 8 in the journal Nature.

Traditional estimates of Earth's ice caps and glaciers have been made using ground measurements from relatively few glaciers to infer what all the world's unmonitored glaciers were doing. Only a few hundred of the roughly 200,000 glaciers worldwide have been monitored for longer than a decade.

One unexpected study result from GRACE was the estimated ice loss from high Asian mountain ranges like the Himalaya, the Pamir and the Tien Shan was only about 4 billion tons of ice annually. Some previous ground-based estimates of ice loss in these high Asian mountains have ranged up to 50 billion tons annually.

"The GRACE results in this region really were a surprise," said Wahr, who also is a fellow at the University of Colorado-headquartered Cooperative Institute for Research in Environmental Sciences. "One possible explanation is that previous estimates were based on measurements taken primarily from some of the lower, more accessible glaciers in Asia and extrapolated to infer the behavior of higher glaciers. But unlike the lower glaciers, most of the high glaciers are located in very cold environments and require greater amounts of atmospheric warming before local temperatures rise enough to cause significant melting. This makes it difficult to use low-elevation, ground-based measurements to estimate results from the entire system."

"This study finds that the world's small glaciers and ice caps in places like Alaska, South America and the Himalayas contribute about .02 inches per year to sea level rise," said Tom Wagner, cryosphere program scientist at NASA Headquarters in Washington. "While this is lower than previous estimates, it confirms that ice is being lost from around the globe, with just a few areas in precarious balance. The results sharpen our view of land ice melting, which poses the biggest, most threatening factor in future sea level rise."

The twin GRACE satellites track changes in Earth's gravity field by noting minute changes in gravitational pull caused by regional variations in Earth's mass, which for periods of months to years is typically because of movements of water on Earth's surface. It does this by measuring changes in the distance between its two identical spacecraft to one-hundredth the width of a human hair.

The GRACE spacecraft, developed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., and launched in 2002, are in the same orbit approximately 137 miles (220 kilometers) apart.

For more on GRACE, visit:

http://www.csr.utexas.edu/grace

http://grace.jpl.nasa.gov

For more information about NASA and agency programs, visit:

http://www.nasa.gov

NASA Seeks Game Changing Technology Payloads for Suborbital Research Flights

NASA is seeking proposals for small technology payloads that could fly on future NASA-sponsored suborbital flights. These future flights will travel to the edge of space and back, testing the innovative new technologies before they're sent to work in the harsh environment of space.

"NASA's Game Changing Development Program focuses on maturing advanced space technologies that may lead to entirely new approaches for the agency's future space missions while providing solutions to significant national needs and adding to our nation’s innovation economy," said Michael Gazarik, director of NASA's Space Technology Program at NASA Headquarters in Washington. "This solicitation offers an opportunity to develop potentially transformative technologies that take advantage of our Flight Opportunities Program platforms, which allow frequent and predictable commercial access to near-space, with easy recovery of intact payloads."

NASA's Game Changing Opportunities research announcement seeks proposals for payloads, vehicle enhancements and onboard facilities for payload integration that will help the agency advance technology development in the areas of exploration, space operations and other innovative technology areas relevant to NASA's missions. Sponsored by NASA's Space Technology Program, the agency expects proposals from entrepreneurs, scientists, technologists, instrument builders, research managers, and vehicle builders and operators.

"This call for proposals is a great opportunity to develop innovative technology development payloads for flight on commercial suborbital, reusable vehicles which have novel ideas and approaches have the potential to revolutionize future space missions," said Stephen Gaddis, Game Changing Development program manager at NASA's Langley Research Center in Hampton, Va.

Special emphasis will be given to proposals that address basic and applied research as well as development for advanced technologies and the development of test articles and techniques for evaluating the articles. Following development, selected payloads will be made available to NASA's Flight Opportunities Program for pairing with appropriate suborbital reusable launch service provider flights.

In August 2011, NASA selected seven U.S. companies that can provide flight services and platforms to test innovative technology payloads through the Flight Opportunities Program. Under this solicitation, the selected Flight Opportunities suborbital reusable launch vehicles could be modified to facilitate integration and payload engineering of future payloads in support of specific research needs.

Proposals will be accepted from U.S. or non-U.S. organizations including NASA centers and other government agencies, federally funded research and development centers, educational institutions, industry and nonprofit organizations.

NASA expects to make approximately 20 awards this summer, with the majority of awards ranging between approximately $50,000 and $125,000 each. Several awards may be made for up to $500,000 in the area of vehicle integration and payload engineering technology enhancements and onboard research facilities to improve platform capabilities.

The Game Changing Opportunities in Technology Development research announcement is available through the NASA Solicitation and Proposal Integrated Review and Evaluation System website at:

http://tinyurl.com/7xk52wa

NASA's Langley Research Center manages the Game Changing Development Program and NASA's Dryden Flight Research Center at Edwards, Calif., manages the Flight Opportunities Program for the agency's Space Technology Program.

For more information on the Game Changing Development activities and information on this solicitation for payloads, visit:

http://go.usa.gov/RPS

For more information about NASA's Flight Opportunities Program, visit:

http://go.usa.gov/REv

Station Astronauts Capture Stunning Views of U.S., Canada, Northern Lights

Astronauts aboard the International Space Station recently filmed what is among the most spectacular night imagery ever taken from space of the United States. The video, comprised of hundreds of sequential still images, will air on NASA Television's video file beginning today.

The imagery also is available on the internet at NASA's Gateway to Astronaut Photography of Earth:

http://eol.jsc.nasa.gov

Taken between Jan. 29-Feb. 3, the images show a continent ablaze with light, from the electric glow of hundreds of cities to a spectacular aurora borealis flickering on the northern horizon. The video includes flights above Mexico showing the entire Gulf Coast and continuing the length of the East Coast. Other video capture scenes from Brownsville, Texas, to the Great Lakes and above the St. Lawrence Seaway. Still another sequence begins in the western U.S. and continues across the Great Plains.

New imagery also shows the aurora during flights above Canada. The imagery was taken using a still camera aboard the station, orbiting 240 miles above Earth. For more about the International Space Station, visit:

http://www.nasa.gov/station

For NASA Television schedules, downlink information and streaming video, visit:

 

http://www.nasa.gov/ntv

Putting the Squeeze On Planets Outside Our Solar System

Just as graphite can transform into diamond under high pressure, liquid magmas may similarly undergo major transformations at the pressures and temperatures that exist deep inside Earth-like planets.
Using high-powered lasers, scientists at Lawrence Livermore National Laboratory and collaborators discovered that molten magnesium silicate undergoes a phase change in the liquid state, abruptly transforming to a more dense liquid with increasing pressure. The research provides insight into planet formation.
"Phase changes between different types of melts have not been taken into account in planetary evolution models," said lead scientist Dylan Spaulding, a University of California, Berkeley graduate student who conducted most of his thesis work at the Laboratory's Jupiter Laser Facility. "But they could have played an important role during Earth's formation and may indicate that extra-solar 'Super-Earth' planets are structured differently from Earth."
Melts play a key role in planetary evolution. The team said that pressure-induced liquid-liquid phase separation in silicate magmas may represent an important mechanism for global-scale chemical differentiation and also may influence the thermal transport and convective processes that govern the formation of a mantle and core early in planetary history. Liquid-liquid phase separation is similar to the difference between oil and vinegar -- they want to separate because they have different densities. In the new research, however, the researchers noticed a sudden change between liquid states of silicate magma that displayed different physical properties even though they both have the same composition when high pressure and temperatures were applied.
The team used LLNL's Janus laser and OMEGA at the University of Rochester to conduct the experiments to achieve the extreme temperatures and pressures that exist in the interiors of exoplanets -- those objects outside our solar system.
In each experiment, a powerful laser pulse generated a shock wave while it traveled through the sample. By looking for changes in the velocity of the shock and the temperature of the sample, the team was able to identify discontinuities that signaled a phase change in the material.
"In this case, the decay in shock-velocity and thermal emission both reverse themselves during the same brief time interval," Spaulding said.
The team concluded that a liquid-liquid phase transition in a silicate composition similar to what would be found in terrestrial planetary mantles could help explain the thermal-chemical evolution of exoplanet interiors.
The research appears in the Feb. 10 edition of the journal, Physical Review Letters.
Other LLNL authors include Jon Eggert, Peter Celliers, Damien Hicks, Gilbert Collins and Ray Smith. Other collaborators include UC Berkeley, the Carnegie Institution of Washington and Howard University.
The work was funded by the National Nuclear Security Administration, the National Science Foundation and the University of California.
The above story is reprinted from materials provided by DOE/Lawrence Livermore National Laboratory. 

1st International Announcement of Opportunity for HAYABUSA Sample Investigation

Japan Aerospace Exploration Agency (JAXA) has been engaged in initial analysis* of Itokawa’s sample brought back by HAYABUSA. On this occasion we would like to inform you of offering the announcement of opportunity for HAYABUSA Sample Investigation.

Through the peer review, JAXA will provide HAYABUSA sample to researcher who submits research proposal in the framework of this Announce of 0pportunity (herein after referred as "AO"). This AO is planned to be conducted a few times. The 1st International AO issues on January 24th 2012.

Please see the appendix.

* "Initial analysis" means the analysis of typical particles to obtain information necessary for categorizing (identification, classification and numbering). Initial analysis is scheduled to end with announce of opportunity.

Appendix

HAYABUSA sample International Announcement of Opportunity (AO)
Outline

1. Objectives of AO
   To maximize scientific achievement of HAYABUSA project through the selection of outstanding research proposal by International AO for Itokawa's Sample Investigation. The objective of AO, therefore, is to contribute to development of planetary science worldwide.



2. Application method
   Proposers apply through "JAXA 1st International Announcement of Opportunity for HAYABUSA Sample Investigation website" which JAXA has prepared as follows.
   
   URL:http://hayabusaao.isas.jaxa.jp/



3. Review method
   JAXA International AO Committee that consists of domestic and foreign experts will review proposals and will select outstanding research.



4. Future plans
   

   Announcement of Opportunity Due date for proposals Completion of review Distribution of sample

   24 January, 2012 7 March, 2012 (15:00 UT) Mid May, 2012 Soonafter the completion of review

   (Details of subsequent AO are to be determined.)

Mission website:

Asteroid Explorer "HAYABUSA" (MUSES-C)
1St International Announcement of Opportunity for HAYABUSA Sample Investigation: A Brief Introduction


original article at http://www.jaxa.jp/press/2012/01/20120124_hayabusa_e.html 

New Image Captures 'Stealth Merger' of Dwarf Galaxies

The dwarf galaxy NGC 4449 is the first dwarf galaxy with an identified stellar stream (faintly seen at the lower right, and in inset). The star stream represents the remains of a smaller satellite galaxy merging with NGC 4449. The inset image shows the stream resolved into red giant stars. (Credit: Image credit and copyright: R. Jay Gabany (Black Bird Obs.); Insert credit: Subaru/Suprime-Cam (NAOJ))

New images of a nearby dwarf galaxy have revealed a dense stream of stars in its outer regions, the remains of an even smaller companion galaxy in the process of merging with its host. The host galaxy, known as NGC 4449, is the smallest primary galaxy in which a stellar stream from an ongoing merger has been identified and studied in detail.
"This is how galaxies grow. You can see the smaller galaxy coming in and getting shredded, eventually leaving its stars scattered through the halo of the host galaxy," said Aaron Romanowsky, a research astronomer at the University of California, Santa Cruz, and coauthor of a paper on the discovery that has been accepted for publication in Astrophysical Journal Letters. The study was carried out by an international team of astronomers led by David Martínez-Delgado of the Max Planck Institute for Astronomy in Heidelberg.
According to modern cosmological theory, large galaxies were built up from smaller progenitors through a hierarchical process of mergers. Astronomers can see many examples of mergers involving massive galaxies, but mergers of two dwarf galaxies have been hard to find. "We should see the same things at smaller scales, with small galaxies eating smaller ones and so on," Romanowsky said. "Now we have this beautiful image of a dwarf galaxy consuming a smaller dwarf."
NGC 4449 is located 12.5 million light-years from Earth and is a member of a group of galaxies in the constellation Canes Venatici. In size and morphology, it is very similar to one of the Milky Way's satellite galaxies, the Large Magellanic Cloud.
The stellar stream in NGC 4449 was first detected by another group of astronomers as a mysterious, faint smudge in digitized photographic plates from the Digitized Sky Survey project, and it is also visible in archival images from the Sloan Digital Sky Survey. But if it had been just a bit fainter, more diffuse, or farther from the host galaxy, it could easily have been missed. The authors of the new study called it a "stealth merger," where an infalling satellite galaxy is nearly undetectable by conventional means, yet has a substantial influence on its host galaxy.
Martínez-Delgado organized a campaign to follow up on the initial report with more detailed observations. R. Jay GaBany, a Bay Area amateur astronomer and astrophotographer with whom Martínez-Delgado has frequently collaborated, obtained exceptionally deep, wide-field images of NGC 4449 with the half-meter Black Bird Observatory telescope (located in the Sierra Nevada mountains). Those images confirmed the presence of a faint substructure in the halo of the galaxy. Romanowsky, along with UCSC graduate student Jacob Arnold, then used the 8.2-meter Subaru Telescope in Hawaii to obtain high-resolution images in which the individual stars in the stellar stream can be seen.
"I don't think I'd ever seen a picture of a galaxy merger where you can see the individual stars," Romanowsky said. "It's really an impressive image."
The new observations support the idea that the stellar haloes around many dwarf galaxies are the remnants of smaller satellites that were shredded in past merger events. The ongoing merger in NGC 4449 may also be responsible for the intense burst of star formation seen in the galaxy. "This galaxy is famous for its starburst activity, and it seems we've found the reason for that. The gravitational interaction of the incoming galaxy has probably disturbed the gas in the main galaxy and caused it to start forming stars," Romanowsky said.
The companion galaxy was also independently discovered by a team of scientists led by UCLA astronomer Michael Rich. Their study, based on images obtained by the Centurion 28-inch telescope located at the Polaris Observatory Association near Frazier Park, California, will be published in the February 9 issue of Nature.
In addition to Martínez-Delgado, Romanowsky, Arnold, and GaBany, the coauthors of the Astrophysical Journal Letters paper include Jean Brody, professor of astronomy and astrophysics at UC Santa Cruz; Francesca Annibali at the Astronomical Observatory of Bologna; Jurgen Fliri at the Observatory of Paris; Stefano Zibetti at the University of Copenhagen; Roeland van der Marel and Alessandra Aloisi at the Space Telescope Science Institute; Hans-Walter Rix and Andrea Maccio at the Max Planck Institute; Taylor Chonis at the University of Texas, Austin; Julio Carballo-Bello at the Canary Astrophysics Institute; J. Gallego-Laborda at Fosca Nit Observatory in Spain; and Michael Merrifield at the University of Nottingham, England.
This research was supported by the National Science Foundation, NASA, and the UCSC-UARC Aligned Research Program.
The above story is reprinted from materials provided by University of California - Santa Cruz. The original article was written by Tim Stephens. 

NASA's Galaxy Evolution Explorer in Standby Mode

NASA's Galaxy Evolution Explorer, or Galex, was placed in standby mode Feb. 7, 2012 as engineers prepare to end mission operations, nearly nine years after the telescope's launch. The spacecraft is scheduled to be decommissioned -- taken out of service -- later this year. The mission extensively mapped large portions of the sky with sharp ultraviolet vision, cataloguing millions of galaxies spanning 10 billion years of cosmic time.
The Galaxy Evolution Explorer launched into space from a Pegasus XL rocket in April of 2003. Since completing its prime mission in the fall of 2007, the mission was extended to continue its census of stars and galaxies.
The mission's science highlights include the discovery of a gigantic comet-like tail behind a speeding star, rings of new stars around old galaxies, and "teenager" galaxies, which help to explain how galaxies evolve. The observatory also helped confirm the existence of the mysterious substance or force known as dark energy, and even caught a black hole devouring a star.
The California Institute of Technology, Pasadena, Calif., leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program, managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission. Caltech manages JPL for NASA.
Graphics and additional information about the Galaxy Evolution Explorer are online at http://www.nasa.gov/galex/ and http://www.galex.caltech.edu/ .

Mars-Bound NASA Rover Carries Coin for Camera Checkup

The camera at the end of the robotic arm on NASA's Mars rover Curiosity has its own calibration target, a smartphone-size plaque that looks like an eye chart supplemented with color chips and an attached penny.
When Curiosity lands on Mars in August, researchers will use this calibration target to test performance of the rover's Mars Hand Lens Imager, or MAHLI. MAHLI's close-up inspections of Martian rocks and soil will show details so tiny, the calibration target includes reference lines finer than a human hair. This camera is not limited to close-ups, though. It can focus on any target from about a finger's-width away to the horizon.
Curiosity, the rover of NASA's Mars Science Laboratory mission, also carries four other science cameras and a dozen black-and-white engineering cameras, plus other research instruments. The spacecraft, launched Nov. 26, 2011, will deliver Curiosity to a landing site inside Mars' Gale Crater in August to begin a two-year investigation of whether that area has ever offered an environment favorable for microbial life.
The "hand lens" in MAHLI's name refers to field geologists' practice of carrying a hand lens for close inspection of rocks they find. When shooting photos in the field, geologists use various calibration methods.
"When a geologist takes pictures of rock outcrops she is studying, she wants an object of known scale in the photographs," said MAHLI Principal Investigator Ken Edgett, of Malin Space Science Systems, San Diego. "If it is a whole cliff face, she'll ask a person to stand in the shot. If it is a view from a meter or so away, she might use a rock hammer. If it is a close-up, as the MAHLI can take, she might pull something small out of her pocket. Like a penny."
Edgett bought the special penny that's aboard Curiosity with funds from his own pocket. It is a 1909 "VDB" cent, from the first year Lincoln pennies were minted, the centennial of Abraham Lincoln's birth, with the VDB initials of the coin's designer -- Victor David Brenner -- on the reverse.
"The penny is on the MAHLI calibration target as a tip of the hat to geologists' informal practice of placing a coin or other object of known scale in their photographs. A more formal practice is to use an object with scale marked in millimeters, centimeters or meters," Edgett said. "Of course, this penny can't be moved around and placed in MAHLI images; it stays affixed to the rover."
The middle of the target offers a marked scale of black bars in a range of labeled sizes. While the scale will not appear in photos MAHLI takes of Martian rocks, knowing the distance from the camera to a rock target will allow scientists to correlate calibration images to each investigation image.
Another part of MAHLI's calibration target displays six patches of pigmented silicone as aids for interpreting color and brightness in images. Five of them -- red, green, blue, 40-percent gray and 60-percent gray -- are spares from targets on NASA Mars rovers Spirit and Opportunity. The sixth, with a fluorescent pigment that glows red when exposed to ultraviolet light, allows checking of an ultraviolet light source on MAHLI. The fluorescent material was donated to the MAHLI team by Spectra Systems, Inc., Providence, R.I.
A stair-stepped area at the bottom of the target, plus the penny, help with three-dimensional calibration using known surface shapes.
Curiosity also carries calibration materials for other science instruments on the rover. "The importance of calibration is to allow data acquired on Mars to be compared reliably to data acquired on Earth," said Mars Science Laboratory Project Scientist John Grotzinger, of the California Institute of Technology, Pasadena.
The MAHLI calibration target, with its penny and a miniscule cartoon of a character named "Joe the Martian," serves an additional function: public engagement.
"Everyone in the United States can recognize the penny and immediately know how big it is, and can compare that with the rover hardware and Mars materials in the same image," Edgett said. "The public can watch for changes in the penny over the long term on Mars. Will it change color? Will it corrode? Will it get pitted by windblown sand?"
The Joe the Martian character appeared regularly in a children's science periodical, "Red Planet Connection," when Edgett directed the Mars outreach program at Arizona State University, Tempe, in the 1990s. Joe was created earlier, as part of Edgett's schoolwork when he was 9 years old and NASA's Mars Viking missions, launched in 1975, were inspiring him to dream of becoming a Mars researcher.
Edgett said, "The Joe the Martian on Curiosity really is a 'thank you' from the MAHLI team to the folks who have provided us with the opportunity to study Mars, the U.S. taxpayers. He is also there to encourage children around the world to set goals that will help them achieve their dreams in whatever interests they pursue."
The Mars Science Laboratory is managed by NASA's Jet Propulsion Laboratory, a division of the Caltech. For more information, visit http://www.nasa.gov/msl .

NASA Small Explorer Mission Celebrates 10 Years and 40,000 X-Ray Flares

On February 5, 2002, NASA launched what was then called the High Energy Solar Spectroscopic Imager (HESSI) into orbit. Renamed within months as the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) after Reuven Ramaty, a deceased NASA scientist who had long championed the mission, the spacecraft's job was to observe giant explosions on the sun called solar flares.
During a solar flare, the gas soars to over 20 million degrees Fahrenheit, and emits X-rays that scientists can use as fingerprints to study these events on the sun. X-rays cannot penetrate Earth's atmosphere, however, so RHESSI observes them from space. Its goal is simple: to understand how the sun so efficiently shoots out such huge amounts of energy and particles.
Ten years since its launch, RHESSI has observed more than 40,000 X-ray flares, helped craft and refine a model of how solar eruptions form, and fueled additional serendipitous science papers on such things as the shape of the sun and thunder-storm-produced gamma ray flashes.
RHESSI is in a class of NASA spacecraft called Small Explorers -- missions that cost under $120 million with highly focused research goals. Launching just after the sun reached its period of maximum activity, known as solar maximum, in 2001, RHESSI was poised to see many explosive bursts of energy from the sun, including both solar flares and another eruption of solar material called coronal mass ejections.
"Except, thanks in part to RHESSI, we don't even separate the biggest explosions into categories like that anymore," says Brian Dennis, the mission scientist for RHESSI at NASA's Goddard Space Flight Center in Greenbelt, Md. "RHESSI has taught us that 'Thou shalt instead say Solar Eruptive Events.' Now we know that one burst of energy in the sun's atmosphere creates both kinds of eruptions. Part of the energy shoots into the sky and becomes a CME (coronal mass ejection). Part of the material is driven down to the sun's surface and appears as the flare. RHESSI's 10 years of observations have helped fill in the holes in this picture."
To accomplish this, RHESSI made use of its one, and only one, instrument, which records both X-rays and even shorter wavelengths of light, gamma rays. The instrument combines high-resolution solar images with "spectroscopic" images that delineate the spectrum of energy coming from any particular point in the image. Together, this helps physically map out energy levels during an explosive event on the sun, as well as track the energy's movement.
For example, to understand how a solar flare forms, one has to understand where the energy to power it comes from. Early RHESSI observations of a flare on April 15, 2002, showed two X-ray sources -- one higher in the sun's atmosphere and one lower. RHESSI's unique spectroscopic imaging capability allowed scientists to interpret this to mean that a huge energy release had originally happened between the two spots: that crucial initiation in the current picture of solar eruptions where a single energy burst in the sun's atmosphere, creates both a CME and a flare.
Since RHESSI observes gamma rays as well as X-rays, it has been able to compare how events emit these two forms of radiation. X-rays generally represent electron activity and gamma rays represent activity from protons and other heavier charged particles called ions, so comparing both helps show how different particle populations move around. Scientists have spotted several flares, including their first one using RHESSI in October 2003, where the gamma rays and X-ray sources do not line up. Such a spatial difference was entirely unexpected and suggests that different circumstances guide the movements of different particle populations.
"This opens up new questions for our model," says Dennis. "The electrons and ions have different masses, but we'd still expect them to appear at the same locations in the flare. Perhaps the ions are accelerated in a different way and end up traveling on different magnetic field lines from the electrons."
In addition to observations of giant solar flares, RHESSI has observed more than 25,000 of a smaller version, known as microflares. These much smaller energy releases are also believed to play a role in how the sun transports energy from its surface up into its atmosphere. RHESSI has found that such flares all occur in active regions over the same range of latitudes on the sun as for the bigger events, so perhaps they are just smaller versions of the same phenomenon.
Another interesting result from RHESSI has nothing to do with flares at all, but with the very shape of the sun. Due to its spin, one expects the sun to be slightly flattened and not a perfect sphere, much the same as the slight flattening of Earth. Pre-RHESSI measurements of the sun, however, showed it to be much flatter than physics would dictate, raising questions of whether scientists had overlooked some fundamental piece of information about the sun's rotation.
RHESSI helped by providing information simply gathered as part of its constant assessment of where its instrument points. To keep perfectly oriented, RHESSI precisely records the position of the sun's horizon, or "limb," some 16 times per second. With such an extensive collection of data, scientists could determine the best ever measurement of the sun's shape. This data suggests the true shape more closely matches what physics predicts.
RHESSI's monitoring of gamma rays throughout the sky also made it a prime tool to measure what are called terrestrial gamma-ray flashes (TGFs), bursts of gamma rays emitted from high in Earth's atmosphere over lightning storms. The first of these had been spotted before, but RHESSI showed that they are more common and more luminous than previously thought. With RHESSI's help, scientists soon realized they occurred upwards of 50 times per day. Indeed, current numbers suggest there may be as many as 400 TGFs daily from thunderstorms at different locations around the world.
"RHESSI made great strides by taking the first high-resolution movies of flares using their high energy radiation," says Dennis. "The original mission was only for two years and we quickly achieved our initial science goals -- but RHESSI didn't stop there. The mission has been extended several times, and this small mission just keeps going and going, collecting great data."
In 2009, NASA extended the mission yet again. Now scientists are working to integrate RHESSI flare observations with data from other solar telescopes such as the Solar TErrestrial RElations Observatory (STEREO), Solar Dynamics Observatory (SDO), SOlar and Heliophysics Observatory (SOHO), and Hinode as they watch the sun's activity rise toward yet another solar maximum, currently predicted for 2013.
The Explorers Program Office at Goddard provides management and technical oversight for the RHESSI mission under the direction of NASA's Science Mission Directorate in Washington, D.C.
For more information about the mission, go to: http://science.nasa.gov/missions/rhessi/