NASA’s Dawn Probe Sees Dwarf Planet Ceres as a Crescent


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After spending several weeks in the shadow of Ceres, NASA’s Dawn spacecraft is finally getting a close-up glimpse of the dwarf planet.

For Those Who Don’t Know About CERES : Ceres is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. It is composed of rock and ice, is 950 kilometers (590 miles) in diameter, and comprises approximately one third of the mass of the asteroid belt. It is the only dwarf planet in the inner Solar System and the only object in the asteroid belt known to be unambiguously rounded by its own gravity.

Ceres’ cratered north pole blazes through the darkness in new images captured by Dawn on April 10. The photos are the highest-resolution views of the world that Dawn has gotten since entering Ceres’ orbit on March 6, NASA officials said.

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Dawn was about 21,000 miles (33,000 kilometers) from the dwarf planet when the pictures were taken, and mission team members promise even better views of Ceres in the months to come.

Full science observations begin April 23, when lighting conditions will be better for Dawn and the probe will be even closer to Ceres — just 8,400 miles (13,500 kilometers) above the surface. Dawn will begin moving even lower down on May 9.

In future weeks, NASA hopes the mission will help scientists better understand a key mystery of Ceres: strange bright spots on its surface that, in some cases, have different temperatures than the terrain surrounding them. Mission scientists still don’t know what the spots are made of.

The $466 million Dawn mission, which launched in September 2007, aims to better characterize the solar system’s early days by studying Ceres and Vesta, two intact protoplanets that are the largest denizens of the asteroid belt between Mars and Jupiter. The probe spent 14 months at the 330-mile-wide (530-kilometer-wide) Vesta in 2011 and 2012, then headed to Ceres.

Mission scientists said they expect that Ceres, which is about 590 miles (950 km) wide, will be wetter than Vesta, and made of different stuff. Some researchers think Ceres may even harbor liquid water beneath its surface, perhaps making the dwarf planet capable of hosting life as we know it.

Source : NBS-news,Sci-news,Wikipedia

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Hubble captures green ‘quasar ghosts’ from past radiation blast


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The NASA/ESA Hubble Space Telescope has imaged a set of enigmatic quasar ghosts — ethereal green objects which mark the graves of these objects that flickered to life and then faded. The eight unusual looped structures orbit their host galaxies and glow in a bright and eerie goblin-green hue. They offer new insights into the turbulent pasts of these galaxies.

Hubble Space Telescope has discovered manifestations from the remote past, bright streams of gas, which look like immense looped objects glowing green, once ionized by quasars that no longer exist.

The telescope, which will turn 25 in 20 days, has taken photos of eight unusual space objects glowing emerald in the depths of space. Light emitting space areas dubbed ‘Hanny’s Voorwerp’ are tens of thousands of light years across.

The first object of this kind was spotted by Dutch schoolteacher Hanny van Arkel in 2007.

Hubble spies eight green filaments lit up by past quasar blasts

The ethereal wisps in these images were illuminated, perhaps briefly, by a blast of radiation from a quasar — a very luminous and compact region that surrounds a supermassive black hole at the center of a galaxy. Galactic material falls inwards towards the central black hole, growing hotter and hotter, forming a bright and brilliant quasar with powerful jets of particles and energy beaming above and below the disc of infalling matter.

In each of these eight images a quasar beam has caused once-invisible filaments in deep space to glow through a process called photoionisation. Oxygen, helium, nitrogen, sulphur and neon in the filaments absorb light from the quasar and slowly re-emit it over many thousands of years. Their unmistakable emerald hue is caused by ionised oxygen, which glows green.

hese objects were found in a spin-off of the Galaxy Zoo project, in which about 200 volunteers examined over 16 000 galaxy images in the SDSS to identify the best candidates for clouds similar to Hanny’s Voorwerp. A team of researchers analysed these and found a total of twenty galaxies that had gas ionised by quasars. Their results appear in a paper in the Astronomical Journal.

Source : RT , Spacetelescope.org

‘Perfect Storm’ Suffocating Star Formation around a Supermassive Black Hole


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High-energy jets powered by supermassive black holes can blast away a galaxy’s star-forming fuel — resulting in so-called “red and dead” galaxies: those brimming with ancient red stars yet little or no hydrogen gas available to create new ones.

Now astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that black holes don’t have to be nearly so powerful to shut down star formation. By observing the dust and gas at the center NGC 1266, a nearby lenticular galaxy with a relatively modest central black hole, the astronomers have detected a “perfect storm” of turbulence that is squelching star formation in a region that would otherwise be an ideal star factory.

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Fig 1. Artist impression of the central region of NGC 1266. The jets from the central black hole are creating turbulence in the surrounding molecular gas, suppressing star formation in an otherwise ideal environment to form new stars. Credit: B. Saxton (NRAO/AUI/NSF)

This turbulence is stirred up by jets from the galaxy’s central black hole slamming into an incredibly dense envelope of gas. This dense region, which may be the result of a recent merger with another smaller galaxy, blocks nearly 98 percent of material propelled by the jets from escaping the galactic center.

“Like an unstoppable force meeting an immovable object, the molecules in these jets meet so much resistance when they hit the surrounding dense gas that they are almost completely stopped in their tracks,” said Katherine Alatalo, an astronomer with the California Institute of Technology in Pasadena and lead author on a paper published in the Astrophysical Journal. This energetic collision produces powerful turbulence in the surrounding gas, disrupting the first critical stage of star formation. “So what we see is the most intense suppression of star formation ever observed,” noted Alatalo.

Previous observations of NGC 1266 revealed a broad outflow of gas from the galactic center traveling up to 400 kilometers per second. Alatalo and her colleagues estimate that this outflow is as forceful as the simultaneous supernova explosion of 10,000 stars. The jets, though powerful enough to stir the gas, are not powerful enough to give it the velocity it needs to escape from the system.

Continue reading ‘Perfect Storm’ Suffocating Star Formation around a Supermassive Black Hole

New Signal May Be Evidence of Dark Matter


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Scientists say they may have discovered a possible dark matter signal coded in the X-rays emanating from two bright objects in the sky.

The findings, set to be published next week in Physical Review Letters, could offer tangible evidence for the existence of dark matter — and help researchers build new tools to search for and study this mysterious stuff.

When it comes to matter in the universe, dark matter is like a backroom political power broker: You never see it, but behind the scenes, it’s been throwing its weight around. The effects of its gravitational influence can be seen in the large-scale structures of the cosmos. Dark matter makes up about 84.5% of the matter in the universe while all the stuff we actually see — stars, galaxies, planets, ourselves — makes up the remaining 15.5%. The enormous galaxies and clusters of galaxies that populate the universe are bantamweights compared to the massive, unseen dark matter ‘halos’ that anchor them.

Dark matter’s formidable gravitational influence is the only way that the strange stuff can be detected, because it’s invisible — it does not interact with light. Physicists have no idea what it’s made of, although they’ve looked for it by building detectors in underground former gold mines, sending satellites into space and other methods.

But now, a team led by researchers at Leiden University in the Netherlands and the École Polytechnique Fédérale de Lausanne in Switzerland say they’ve discovered a signal that could be a sign of dark matter.

The scientists looked at X-ray emissions coming from the Andromeda galaxy and the Perseus galaxy cluster, collected by the European Space Agency’s XMM-Newton space telescope. After accounting for all the light particles (called photons) emanating from known sources in the Andromeda galaxy, they were left with a strange set of photons that had no known source. The found the same light signature emanating from the Perseus cluster. And when they turned their attention to the Milky Way, they found signs of this signal in our home galaxy, as well.

“It is consistent with the behavior of a line originating from the decay of dark matter particles,” the authors wrote in a pre-print of the study.

This weird light signal, they think, could be coming from the destruction of a hypothetical particle called a sterile neutrino (which, if it exists, might help explain dark matter). But it’s going to take a lot of follow-up study to determine whether this signal is a scientific breakthrough or an anomalous blip.

“Future detections or non-detections of this line in multiple astrophysical targets may help to reveal its nature,” the study authors wrote.

Japan’s upcoming Astro-H mission, they said, might allow them to do just that.

Source :Science Tech Today

Isro to Test-Fly Heaviest Rocket, Crew Module on December 18


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India will test-fly its heaviest and upgraded rocket – the Geosynchronous Satellite Launch Vehicle (GSLV-Mark III) – on December 18, space agency Isro said Friday.

According to a tweet by the Indian Space Research Organisation (Isro), the 630-tonne rocket will be powered by liquid and solid fuel engines while the cryogenic stage/engine will be a passive one.

The rocket will also carry a crew module to test its re-entry characteristics.

“The main purpose of the mission is to test the atmospheric characteristics and stability of the rocket on its way up. We also decided to use this opportunity to test one component of the crew module – a human space mission that India may embark on at a later date,” M.Y.S Prasad, director of the Satish Dhawan Space Centre in Sriharikota, told reporters in a recent interaction.

The experimental mission will cost Rs. 155 crores and will not carry any satellite as the cryogenic engine needed for the purpose is still under development, he said.

“This will be India’s new launch vehicle. It is bigger and can carry satellites up to four tonnes,” said GSLV Mark III project director S. Somanath.

The main objective of the crew module is to demonstrate its re-entry flight and aero braking, and end-to-end parachute system validation.

The rocket will go up to 126km and the crew capsule will then detach and fall into the Bay of Bengal, 20 minutes after blast-off.

The descent speed of the crew module will be controlled on board motors for some distance and then by three parachutes.

The module will splash down 600km from Port Blair and 1,600km from the space centre. The capsule will be recovered by an Indian Coast Guard or Indian Navy ship.

Source : NDTV

The Fastest Stars in the Universe May Approach Light Speed


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Our sun orbits the Milky Way’s center at an impressive 450,000 mph. Recently, scientists have discovered stars hurtling out of our galaxy at a couple million miles per hour. Could there be stars moving even faster somewhere out there?

After doing some calculations, Harvard University astrophysicists Avi Loeb and James Guillochon realized that yes, stars could go faster. Much faster. According to their analysis, which they describe in two papers recently posted online, stars can approach light speed. The results are theoretical, so no one will know definitively if this happens until astronomers detect such stellar speedsters—which, Loeb says, will be possible using next-generation telescopes.

But it’s not just speed these astronomers are after. If these superfast stars are found, they could help astronomers understand the evolution of the universe. In particular, they give scientists another tool to measure how fast the cosmos is expanding. Moreover, Loeb says, if the conditions are right, planets could orbit the stars, tagging along for an intergalactic ride. And if those planets happen to have life, he speculates, such stars could be a way to carry life from one galaxy to another.

It all started in 2005 when a star was discovered speeding away from our galaxyfast enough to escape the gravitational grasp of the Milky Way. Over the next few years, astronomers would find several more of what became known as hypervelocity stars. Such stars were cast out by the supermassive black hole at the center of the Milky Way. When a pair of stars orbiting each other gets close to the central black hole, which weighs about four million times as much as the sun, the three objects engage in a brief gravitational dance that ejects one of the stars. The other remains in orbit around the black hole.

Loeb and Guillochon realized that if instead you had two supermassive black holes on the verge of colliding, with a star orbiting around one of the black holes, the gravitational interactions could catapult the star into intergalactic space at speeds reaching hundreds of times those of hypervelocity stars.

This appears to be the most likely scenario that would produce the fastest stars in the universe, Loeb says. After all, supermassive black holes collide more often than you might think. Nearly all galaxies have supermassive black holes at their centers, and nearly all galaxies were the product of two smaller galaxies merging. When galaxies combine, so do their central black holes.

Loeb and Guillochon calculated that merging supermassive black holes would eject stars at a wide range of speeds. Only some would reach near light speed, but many of the rest would still be plenty fast. For example, Loeb says, the observable universe could have more than a trillion stars moving at a tenth of light speed, about 67 million miles per hour.

Because a single, isolated star streaking through intergalactic space would be so faint, only powerful future telescopes like the James Webb Space Telescope , planned for launch in 2018, would be able to detect them. Even then, telescopes would likely only see the stars that have reached our galactic neighborhood. Many of the ejected stars probably would have formed near the centers of their galaxies, and would have been thrown out soon after their birth. That means that they would have been traveling for the vast majority of their lifetimes. The star’s age could therefore approximate how long the star has been traveling. Combining travel time with its measured speed, astronomers can determine the distance between the star’s home galaxy and our galactic neighborhood.

If astronomers can find stars that were kicked out of the same galaxy at different times, they can use them to measure the distance to that galaxy at different points in the past. By seeing how the distance has changed over time, astronomers can measure how fast the universe is expanding.

These superfast rogue stars could have another use as well. When supermassive black holes smash into each other, they generate ripples in space and time called gravitational waves, which reveal the intimate details of how the black holes coalesced. A space telescope called eLISA, scheduled to launch in 2028, is designed to detect gravitational waves. Because the superfast stars are produced when black holes are just about to merge, they would act as a sort of bat signal pointing eLISA to possible gravitational wave sources.

The existence of these stars would be one of the clearest signals that two supermassive black holes are on the verge of merging, says astrophysicist Enrico Ramirez-Ruiz of the University of California, Santa Cruz. Although they may be hard to detect, he adds, they will provide a completely novel tool for learning about the universe.

In about 4 billion years, our own Milky Way Galaxy will crash into the Andromeda Galaxy. The two supermassive black holes at their centers will merge, and stars could be thrown out. Our own sun is a bit too far from the galaxy’s center to get tossed, but one of the ejected stars might harbor a habitable planet. And if humans are still around, Loeb muses, they could potentially hitch a ride on that planet and travel to another galaxy. Who needs warp drive anyway?

Source : wired.com

Discovery of a Pulsar and Supermassive Black Hole Pairing Could Help Unlock the Enigma of Gravity


Last year, the very rare presence of a pulsar (named SGR J1745-2900) was also detected in the proximity of a supermassive black hole (Sgr A**, made up of millions of solar masses), but there is a combination that is still yet to be discovered: that of a pulsar orbiting a ‘normal’ black hole; that is, one with a similar mass to that of stars.

The intermittent light emitted by pulsars, the most precise timekeepers in the universe, allows scientists to verify Einstein’s theory of relativity, especially when these objects are paired up with another neutron star or white dwarf that interferes with their gravity. However, this theory could be analysed much more effectively if a pulsar with a black hole were found, except in two particular cases, according to researchers from Spain and India.

Pulsars are very dense neutron stars that are the size of a city (their radius approaches ten kilometres), which, like lighthouses for the universe, emit gamma radiation beams or X-rays when they rotate up to hundreds of times per second. These characteristics make them ideal for testing the validity of the theory of general relativity, published by Einstein between 1915 and 1916.

“Pulsars act as very precise timekeepers, such that any deviation in their pulses can be detected,” Diego F. Torres, ICREA researcher from the Institute of Space Sciences (IEEC-CSIC), explains to SINC. “If we compare the actual measurements with the corrections to the model that we have to use in order for the predictions to be correct, we can set limits or directly detect the deviation from the base theory.”

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These deviations can occur if there is a massive object close to the pulsar, such as another neutron star or a white dwarf. A white dwarf can be defined as the stellar remnant left when stars such as our Sun use up all of their nuclear fuel. The binary systems, comprised of a pulsar and a neutron star (including double pulsar systems) or a white dwarf, have been very successfully used to verify the theory of gravity.

Until now scientists had considered the strange pulsar/black hole pairing to be an authentic ‘holy grail’ for examining gravity, but there exist at least two cases where other pairings can be more effective. This is what is stated in the study that Torres and the physicist Manjari Bagchi, from the International Centre of Theoretical Sciences (India) and now postdoc at the IEEC-CSIC, have published in the Journal of Cosmology and Astroparticle Physics. The work also received an Honourable Mention in the 2014 Essays of Gravitation prize.

The first case occurs when the so-called principle of strong equivalence is violated. This principle of the theory of relativity indicates that the gravitational movement of a body that we test only depends on its position in space-time and not on what it is made up of, which means that the result of any experiment in a free fall laboratory is independent of the speed of the laboratory and where it is found in space and time.

The other possibility is if one considers a potential variation in the gravitational constant that determines the intensity of the gravitational pull between bodies. Its value is G = 6.67384(80) x 10-11 N m2/kg2. Despite it being a constant, it is one of those that is known with the least accuracy, with a precision of only one in 10,000.

In these two specific cases, the pulsar-black hole combination would not be the perfect ‘holy grail’, but in any case scientists are anxious to find this pair, because it could be used to analyse the majority of deviations. In fact, it is one of the desired objectives of X-ray and gamma ray space telescopes (such as Chandra, NuStar or Swift), as well as that of large radio telescopes that are currently being built, such as the enormous ‘Square Kilometre Array’ (SKA) in Australia and South Africa.

Source : Daily galaxy

The Dawn Spacecraft Is Closing in on Dwarf Planet Ceres


NASA’s Dawn spacecraft is currently en route to the asteroid belt where it will rendezvous with the region’s largest celestial body, Ceres. As a sneak preview, the spacecraft has snapped its best-yet image of the dwarf planet.

The image was snapped at a distance of 740,000 miles (1.2 million km) from Ceres. The dwarf planet features an average diameter of about 590 miles (950 km).

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At 9-pixels wide, the image isn’t much. It doesn’t hold a candle to the one previously snapped by the Hubble Space Telescope:

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But just wait until Dawn arrives at Ceres. In early 2015, the spacecraft will begin delivering images at much higher resolution.

Since launching in 2007, Dawn has visited Vesta, a giant protoplanet currently located 104 million miles (168 million kilometers) away from Ceres.

Images: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

Source : io9.com

DON’T FORGET TO SEE NASA ‘S 21th CENTURY SPACE CAPSULE !


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NASA’s newest capsule, designed to take astronauts deeper into space than ever before, is ready to launch to space for the first time on Thursday (Dec. 4).

The space agency’s new Orion space capsule is scheduled to fly to orbit on an unmanned test flight at 7:05 a.m. EST (1205 GMT) from Space Launch Complex 37 here in Cape Canaveral, Florida Thursday before being recovered in the Pacific Ocean 4.5 hours later. Orion is currently positioned on top of the United Launch Alliance Delta 4 Heavy rocket that will deliver it into space on its ambitious test flight, and everything is looking good for launch day.

ORION FLIGHT TEST ANIMATED VIDEO BY NASA

Orion — which was built for NASA by Lockheed Martin — will orbit Earth twice during its test flight, called Exploration Test Flight-1 (EFT-1). On its second orbit, the spacecraft will climb about 3,600 miles (5,793 kilometers) above Earth’s surface, farther than any spacecraft made for humans has flown in more than 40 years.

You can watch the historic Orion flight live on Space.com via NASA TV Thursday at 4:30 a.m. EST (0930 GMT).

NASA plans to use the Orion capsule as part of a system that could bring humans to Mars or an asteroid towed into orbit around the moon for the first time.

Source : Space.com

Hayabusa 2 launches on audacious asteroid adventure


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Japan’s Hayabusa 2 asteroid mission blasts off from Tanegashima Space Center aboard an H-2A rocket. Credit: JAXA

A Japanese H-2A launcher blasted off from an idyllic island spaceport Tuesday, dispatching a daring six-year expedition to bring a piece of an asteroid back to Earth.

The Hayabusa 2 mission’s roundtrip voyage began at 0422 GMT Wednesday (11:22 p.m. EST Tuesday) with a thunderous ascent from Tanegashima Space Center in southern Japan.

The 1,300-pound spacecraft rode a hydrogen-fueled H-2A rocket through clouds hanging over the seaside spaceport, leaving a twisting column of exhaust in its wake before disappearing hundreds of miles over the Pacific Ocean.

The rocket’s upper stage engine fired two times to accelerate Hayabusa 2 on a speedy departure fast enough to break free of the pull of Earth’s gravity.

The robotic explorer, packed with four stowaway landers to be deployed to the asteroid’s surface, separated from the H-2A rocket at 0609 GMT (1:09 a.m. EST). Applause could be heard in a live webcast of the launch provided by the Japan Aerospace Exploration Agency, which manages the Hayabusa 2 mission.

The launch marked the opening chapter in the most ambitious mission to an asteroid ever attempted. The roundtrip journey will take six years to complete, and Hayabusa 2 promises to expand scientists’ understanding of how asteroids may have seeded Earth with water and organic molecules, the building blocks of life.

Hayabusa 2 is heading for asteroid 1999 JU3, a carbon-rich world just 900 meters — about 3,000 feet — across with a tenuous gravity field 60,000 times weaker than Earth’s.

The mission follows up on the achievements of Japan’s Hayabusa 1 probe, which made the first roundtrip flight to an asteroid from 2003 to 2010. The first Hayabusa mission encountered several crippling problems, including a fuel leak, failures in its pointing system, and a glitch with the craft’s sample collection system.

Despite the challenges, the spacecraft returned to Earth in 2010 — a few years late and carrying a fraction of the asteroid specimens intended. But Japanese scientists found microscopic samples from asteroid Itokawa — Hayabusa 1’s research subject — inside the probe’s landing vehicle.

The success vaulted Japan into the big leagues of solar system exploration.

“Many scientific milestones have been achieved from asteroid observations and samples from the asteroid Itokawa,” said Tetsuo Tanaka, associate director general of JAXA’s Lunar and Planetary Exploration Program Group. “Going to a far-off asteroid and returning with samples from it for the first time, these are tremendous technological challenges and our success in meeting them has brought worldwide admiration.”

“For the Hayabusa 2 project, Japan’s development of its own deep space exploration technology aims to lead the world in that technical field,” Tanaka said. “The Hayabusa 2 project sets new challenges for Japan’s unique technologies. How we face those challenges and how we use (the) project results will surely bring new impacts to the world.”

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Artist’s concept of the Hayabusa 2 spacecraft at asteroid 1999 JU3. Credit: JAXA

Continue reading Hayabusa 2 launches on audacious asteroid adventure