2014년 1월 30일 목요일

First-Ever Weather Map of Failed Star Reveals Patchy Alien Clouds

Scientists have created the first weather map of a space oddity known as a brown dwarf, revealing a rare glimpse at alien weather patterns on the failed, wannabe star.

The map shows the weather on the surface of WISE J104915.57-531906.1B (called Luhman 16B for short), the nearest brown dwarf to Earth at 6.5 light-years away. Scientists mapped the light and dark features of the failed star's surface, according to officials with the European Southern Observatory, whose Very Large Telescope in Chile contributed to the new science. You can take video tour of the brown dwarf and its weather map on SPACE.com.

Brown dwarfs are called failed stars because they are larger than gas giant planets like Jupiter, yet still too small to produce nuclear fusion like a true star. Scientists have only found a few hundred of the odd objects, with the first confirmed 20 years ago, ESO officials said.

"Previous observations have inferred that brown dwarfs have mottled surfaces, but now we can start to directly map them," the new study's lead author, Ian Crossfield of the Max Planck Institute for Astronomy, said in a statement. "What we see is presumably patchy cloud cover, somewhat like we see on Jupiter."

Crossfield and his team found that Luhman 16B probably harbors gaseous clouds made of iron and other minerals in a mostly hydrogen atmosphere. The brown dwarf rotates fully about every four hours. Weather on the brown dwarf would not be favorable for humans, however. Temperatures soar to about 2,000 degrees Fahrenheit (1,100 degrees Celsius), Max Planck officials said.

Luhman 16B is one in a pair of brown dwarfs in the southern constellation of Vela, the sail. Its brighter counterpart is known as Luhman 16A. In another study, scientists were able to dissect what is happening in different atmospheric layers on both Luhman 16B and Luhman 16A.

The two brown dwarfs were first discovered in 2013 using data from NASA's WISE space telescope, which maps the sky in infrared light.
Scientists used Doppler imaging to create the Luhman 16B weather map, which somewhat resembles satellite weather views of Earth, Max Planck officials wrote in a news release.

"In the future, we will be able to watch cloud patterns form, evolve and dissipate — eventually, maybe exo-meteorologists will be able to predict whether a visitor to Luhman 16B can expect clear or cloudy skies," Crossfield said in a statement.

By examining weather on brown dwarfs, scientists might be able to better understand how the atmospheres of giant planets outside of the solar system work, researchers have said.

"We've learned that the weather patterns on these brown dwarfs are quite complex," Beth Biller, leader of the second study detailing the atmospheric layers, said in a statement. "The cloud structure of the brown dwarf varies quite strongly as a function of atmospheric depth and cannot be explained with a single layer of clouds."

Source of Article: Space.com
By: Miriam Kramer, Staff Writer

Bizarre Magnetic Particle Revealed in Ultra-Cold Lab Experiment

Bizarre magnetic behavior that was predicted by a famous physicist more than 80 years ago has finally been demonstrated in the lab, according to a new study.

The behavior of an electron in response to a magnetic monopole, or a solitary magnet with just a north pole, has been demonstrated in an ultra-cold material that mimics a natural magnetic system. And the monopole and electron system behaves just as English physicist Paul Dirac predicted it would in 1931.

Though the new experiment, described today (Jan. 29) in the journal Nature, doesn't prove that such monopoles exist outside the lab in other magnetic systems, it could help physicists know what to look for in nature, said study co-author David Hall, a physicist at Amherst College in Massachusetts.

Magnetic monopoles

All known magnets have a north and south pole: Break a magnetic compass needle in two, for instance, and there will always be two smaller magnets with both poles. 
"You can slice up your needle as much as you like and you can even get down to the atomic level, and you'll still have a north pole and a south pole," Hall told LiveScience.  Even electrons and protons have two poles.

This is a mystery because many physicists believe that a magnetic monopole — a magnet with just one pole — should exist. For instance, monopoles would explain why the electric charge of subatomic particles such as electrons and protons always come in discrete units of a fundamental charge, Hall said.

And if such magnetic monopoles exist, they likely formed just after the Big Bang when all of space was much hotter and denser than it is today; the conditions may have been energetic enough to form these bizarre magnetic particles, scientists have said.

In 1931, Dirac tried to imagine how this monopole could be consistent with the Standard Model, the reigning physics theory that describes the behavior of tiny particles.

He predicted that a magnetic monopole would leave a little whirlpool trail as it passed through an electron, with a blank corridor in the middle where the electron is completely absent, terminating in the magnetic monopole. (In quantum theory, electrons aren't solid masses with fixed boundaries, but rather fuzzy blobs that other objects can pass through.)

Revealing vortex

Unfortunately, scientists have searched in vain for natural monopoles, so it was difficult to 
test Dirac's theory.

To do so, Hall and his colleagues cooled rubidium atoms to just a billionth of a degree above absolute zero. At this temperature, the atoms display weird quantum behavior, essentially acting like a single wave instead of an aggregation of particles.

They used one rubidium atom to mimic an electron, and then created the magnetic field of a monopole by tweaking the alignment of millions of other rubidium atoms, each of which essentially acts like a tiny compass needle pointing in a slightly different way.

They then took pictures of the "electron" as it interacted with the "magnetic field."
Sure enough, as the synthetic monopole encountered the electron, it created a whirling vortex and a corridor region with no atoms that terminates at the center, just as Dirac predicted, Hall said.

The work "is a beautiful demonstration of quantum simulation, a growing field that uses real quantum systems to model others that are difficult to make, calculate, or observe," said Lindsay Leblanc, a physicist at the University of Alberta in Canada, who wrote a News & Views article about the new study in Nature.

Source of Article: Space.com
By: Tia Ghose, Staff Writer

What's the Universe Made Of? Math, Says Scientist

Scientists have long used mathematics to describe the physical properties of the universe. But what if the universe itself is math? That's what cosmologist Max Tegmark believes.

In Tegmark's view, everything in the universe — humans included — is part of a mathematical structure. All matter is made up of particles, which have properties such as charge and spin, but these properties are purely mathematical, he says. And space itself has properties such as dimensions, but is still ultimately a mathematical structure.

"If you accept the idea that both space itself, and all the stuff in space, have no properties at all except mathematical properties," then the idea that everything is mathematical "starts to sound a little bit less insane," Tegmark said in a talk given Jan. 15 here at The Bell House. The talk was based on his book "Our Mathematical Universe: My Quest for the Ultimate Nature of Reality" (Knopf, 2014).

"If my idea is wrong, physics is ultimately doomed," Tegmark said. But if the universe really is mathematics, he added, "There's nothing we can't, in principle, understand."

Nature is full of math

The idea follows the observation that nature is full of patterns, such as the Fibonacci sequence, a series of numbers in which each number is the sum of the previous two numbers. The flowering of an artichoke follows this sequence, for example, with the distance between each petal and the next matching the ratio of the numbers in the sequence.

The nonliving worldalso behaves in a mathematical way. If you throw a baseball in the air, it follows a roughly parabolic trajectory. Planets and other astrophysical bodies follow elliptical orbits.

"There's an elegant simplicity and beauty in nature revealed by mathematical patterns and shapes, which our minds have been able to figure out," said Tegmark, who loves math so much he has framed pictures of famous equations in his living room.

One consequence of the mathematical nature of the universe is that scientists could in theory predict every observation or measurement in physics. Tegmark pointed out that mathematics predicted the existence of the planet Neptune, radio waves and the Higgs boson particle thought to explain how other particles get their mass.

Some people argue that math is just a tool invented by scientists to explain the natural world. But Tegmark contends the mathematical structure found in the natural world shows that math exists in reality, not just in the human mind.
And speaking of the human mind, could we use math to explain the brain?

Mathematics of consciousness

Some have described the human brain as the most complex structure in the universe. Indeed, the human mind has made possible all of the great leaps in understanding our world.

Someday, Tegmark said, scientists will probably be able to describe even consciousness using math. (Carl Sagan is quoted as having said, "the brain is a very big place, in a very small space.")

"Consciousness is probably the way information feels when it's being processed in certain, very complicated ways," Tegmark said. He pointed out that many great breakthroughs in physics have involved unifying two things once thought to be separate: energy and matter, space and time, electricity and magnetism. He said he suspects the mind, which is the feeling of a conscious self, will ultimately be unified with the body, which is a collection of moving particles.

But if the brain is just math, does that mean free will doesn't exist, because the movements of particles could be calculated using equations? Not necessarily, he said.
One way to think of it is, if a computer tried to simulate what a person will do, the computation would take at least the same amount of time as performing the action. So some people have suggested defining free will as an inability to predict what one is going to do before the event occurs.

But that doesn't mean humans are powerless. Tegmark concluded his talk with a call to action: "Humans have the power not only to understand our world, but to shape and improve it."

Source of Article: Space.com
By: Tanya Lewis, Staff Writer

On Mars, NASA's Curiosity Rover Seeks Smoother Road to Reduce Wheel Damage

NASA engineers are looking for ways to reduce the wear and tear on the Mars rover Curiosity's wheels, which have accumulated an increasing number of dings and punctures over the last few months.

Curiosity's handlers are driving the 1-ton rover more cautiously now and are checking the condition of its wheels frequently, NASA officials said. The rover team is also considering sending Curiosity over a 3-foot-tall (1 meter) sand dune soon to access a potentially smoother, less rocky route to its ultimate science destination, the foothills of the towering Mount Sharp.

"The decision hasn't been made yet, but it is prudent to go check," Curiosity project manager Jim Erickson, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a statement.

"We'll take a peek over the dune into the valley immediately to the west to see whether the terrain looks as good as the analysis of orbital images implies," Erickson added, referring to pictures snapped by NASA's Mars Reconnaissance Orbiter.

Engineers at JPL are also testing out techniques that may help mitigate Curiosity's wheel wear, including driving the rover backward and engaging only four of its six wheels at any one time. This latter strategy could prevent some punctures that occur when Curiosity's rear wheels push its middle and front wheels against sharp rocks, officials said.  

The Curiosity rover, which landed inside Mars' huge Gale Crater in August 2012, is in the middle of a long trek to the base of Mount Sharp, which rises about 3 miles (5 kilometers) into the Martian sky from Gale's center. Scientists want Curiosity to climb up the mountain's foothills, reading a history of the Red Planet's changing environmental conditions as it goes.

While Curiosity likely won't reach Mount Sharp until the middle of the year, engineers are already preparing to do science work there. For example, they've used a test rover on the ground to see how well Curiosity can drill into rock while perched on a slope.
The early returns from these trials are promising, team members said.

"These tests are building confidence for operations we are likely to use when Curiosity is on the slopes of Mount Sharp," said JPL's Daniel Limonadi, systems engineering leader for surface sampling with the rover's arm.

The rover team is currently examining photos taken by Curiosity to determine whether or not to cross the small sand dune. Mission scientists and engineers are also evaluating potential routes to a site called "KMS-9," where the rover may break out its trusty drill once again.

"At KMS-9, we see three terrain types exposed and a relatively dust-free surface," said science team collaborator Katie Stack of Caltech in Pasadena.
Curiosity has driven a total of 3.04 miles (4.89 kilometers) since arriving on Mars, officials said. The robot thus has a long way to go to catch its older, smaller cousin Opportunity, which has racked up 24 miles (38.7 km) to date since its January 2004 touchdown on the Red Planet.

Source of Article: Space.com
By: Mike Wall, Senior Writer

2014년 1월 19일 일요일

Japan to Test Space Junk Cleanup Tether Soon: Report

Japanese scientists are getting ready to launch a test of a space junk-cleaning tether, according to press reports.
Japan Aerospace Exploration Agency (JAXA) researchers are developing an electrodynamic tether designed to generate electricity that will slow down space-based debris, according to a report from Agence France Presse.

The slowed-down space junk will fall into lower and lower orbits until burning up harmlessly in Earth's atmosphere.

Scientists are planning to launch a satellite that will test part of the system on Feb. 28. "We have two main objectives in the trial next month," Masahiro Nohmi, associate professor at Kagawa University, who is working with JAXA on the project, told the AFP. "First, to extend a 300-metre (1,000-foot) tether in orbit and secondly to observe the transfer of electricity." 
"The experiment is specifically designed to contribute to developing a space debris cleaning method," Nohmi said.

The scientists aren't planning on capturing any orbital debris during February's test launch. However, that could be the goal of a future test. AFP also reports that JAXA may launch a tether test sometime in 2015.

Upper stages of launch vehicles, defunct satellites, flecks of paint and other pieces of fast-moving space junk can all threaten active spacecraft. In 1996, a French satellite was damaged by debris from a rocket that exploded 10 years earlier, and a 2007 anti-satellite test launched by China introduced more than 3,000 pieces of debris to space, according to NASA.

As of Sept. 2013, NASA officials estimate there are more than 500,000 pieces of debris the size of a marble or larger orbiting Earth. More than 20,000 pieces of space junk are larger than a softball, but there are millions more that are too small to track, NASA officials have said.

Aside from the tether idea, scientists have also come up with other methods for cleaning up space. CleanSpace One is a spacecraft developed by the company Swiss Space Systems and is designed to grapple satellites and plunge them both into Earth's atmosphere. The robotic Phoenix spacecraft would scavenge parts off derelict satellites to use in new space operations on orbit.

Source of Article: Space.com
By: Miriam Kramer, Staff Writer

Giant Planet-Forming Ring Spotted Surprisingly Far from Young Star

Alien planets may be forming inside a giant gas ring located surprisingly far from its young parent star, scientists say. 

In fact, the planet-forming region is so far from its star — about five times the distance between our own sun and Neptune — that it appears to be the first time researchers have seen such an arrangement for the birth of alien planets. 

Japanese astronomers spotted the giant planet-forming ring while studying new images of the star named HD 142527 taken by the Atacama Large Millimeter/submillimeter Array, or ALMA, in the Chilean desert. They created a video animation of the strange planet nursery to illustrate the discovery. The star is located about 450 light-years away from Earth and is around 2 million years old.

The powerful radio telescopes that make up ALMA offer astronomers a chance to peek at cosmic phenomena that are normally invisible. By detecting light with very short wavelengths, in the millimeter and submillimeter range, ALMA can spot the clouds of gas and dust where new stars are form, as well as the disks of debris around stare where planets are born. 

The new ALMA observations of HD 142527 found that the star is surrounded by cosmic dust that could be smashing together to form planets. Especially encouraging is a bright "knot" in on the northern side of this disk — a submillimeter emission that is 30 times stronger than the southern side emission.

"We are very surprised at the brightness of the northern side," Misato Fukagawa, an assistant professor at Osaka University, said in a statement. "I have never seen such a bright knot in such a distant position. This strong submillimeter emission can be interpreted as an indication that large amount of material is accumulated in this position. When a sufficient amount of material is accumulated, planets or comets can be formed here."

Fukagawa and colleagues believe that if the ring has a ratio of dust to gas (1 to 100) comparable to other solar systems, then giant gas planets several times more massive than Jupiter could be forming in the disk. But if this dense knot in the ring has a higher ratio of dust, it could spawn a "dust trap" that gives rise to Earth-like rocky planets and small bodies like comets.
In any case, the solar system HD "offers a rare opportunity for us to directly observe the critical moment of planet formation and can provide new insights into the origin of wide-orbit planetary bodies," the scientists wrote in their paper posted on the preprint service ArXiv.org.

The scientists say they hope to get more precise measurements of the amount of gas in the disk to identify what kinds of planets might be forming around the baby star. They also hope ALMA can help them spot even more planet-forming disks around other stars.

"HD 142527 is a peculiar object, as far as our limited knowledge goes," Fukagawa added. "Our final goal is to reveal the major physical process which controls the formation of planets. To achieve this goal, it is important to obtain a comprehensive view of the planet formation through observations of many protoplanetary disks."

Source of Article: Space.com
By: Megan Gannon, News Editor

Mystery Rock 'Appears' in Front of Mars Rover

After a decade of exploring the Martian surface, the scientists overseeing veteran rover Opportunity thought they’d seen it all. 

That was until a rock mysteriously "appeared" a few feet in front of the six-wheeled rover a few days ago.
News of the errant rock was announced by NASA Mars Exploration Rover lead scientist Steve Squyres of Cornell University at a special NASA Jet Propulsion Laboratory "10 years of roving Mars" event at the California Institute of Technology (Caltech), Pasadena, Calif., on Thursday night. The science star-studded public event was held in celebration of the decade since twin rovers Spirit and Opportunity landed on the red planet in January 2004.

While chronicling the scientific discoveries made by both rovers over the years, Squyres discussed the recent finding of suspected gypsum near the rim of Endeavour Crater — a region of Meridiani Planum that Opportunity has been studying since 2011 — and the discovery of clays that likely formed in a pH-neutral wet environment in Mars past. While these discoveries have been nothing short of groundbreaking, Squyres shared the Mars rover's team's excitement for that one strange rock, exclaiming: "Mars keeps throwing new stuff at us!"

In a comparison of recent photographs captured by the rover’s panoramic camera, or Pancam, on sol 3528 of the mission, only bare bedrock can be seen. But on sol 3540, a fist-sized rock had appeared (raw Pancam images can be found in the mission archive). MER scientists promptly nicknamed the object “Pinnacle Island."

"It's about the size of a jelly doughnut," Squyres told Discovery News. "It was a total surprise, we were like 'wait a second, that wasn't there before, it can't be right. Oh my god! It wasn't there before!’ We were absolutely startled."
But the rover didn't roll over that area, so where did Pinnacle Island come from?

Only two options have so far been identified as the rock's source: 1) The rover either "flipped" the object as it maneuvered or, 2) it landed there, right in front of the rover, after a nearby meteorite impact event. The impact ejecta theory, however, is the least likely of the two.

"So my best guess for this rock … is that it's something that was nearby," said Squyres. "I must stress that I’m guessing now, but I think it happened when the rover did a turn in place a meter or two from where this rock now lies."

Opportunity's front right steering actuator has stopped working, so Squyres identified that as the possible culprit behind the whole mystery.

Each wheel on the rover has its own actuator. Should an actuator jam or otherwise fail, the robot's mobility can suffer. In the case of this wheel, it can no longer turn left or right. "So if you do a turn in place on bedrock," continued Squyres, "as you turn that wheel across the rock, it's gonna kinda 'chatter.'" This jittery motion across the bedrock may have propelled the rock out of place, "tiddlywinking" the object from its location and flipping it a few feet away from the rover.

Never missing a scientific opportunity, Opportunity scientists hope to study the bright rock. “It obligingly turned upside down, so we’re seeing a side that hasn’t seen the Martian atmosphere in billions of years and there it is for us to investigate. It’s just a stroke of luck,” he said.

“You think of Mars as being a very static place and I don’t think there’s a smoking hole nearby so it’s not a bit of crater ejecta, I think it’s something that we did … we flung it.”
Although this is the leading theory behind the case of the random rock, Squyres pointed out that the investigation is still under way and it will be a few days before his team can definitively say where Pinnacle Island came from.

Opportunity has outlived its 3-month primary missionby ten years, notching up nearly 23 miles on the odometer so far. Sister rover Spirit succumbed to the Martian elements in 2009 when it became stuck in a sand trap in Gusev Crater. Spirit’s mission was declared lost when it stopped transmitting in March 2010, likely drained of energy. 

Although Spirit had the rougher time on Mars and was the first to die, it was also a huge success, aiding our understanding of Mars' geological history and outliving its warranty by 5 years. But now it's just Opportunity and Mars' new arrival Curiosity that soldier on to reveal more than we ever dreamed about our neighboring Red Planet.

As the NASA Jet Propulsion Laboratory rover drivers, scientists and engineers recounted stories of their beloved robots on Thursday, it became very clear that they aren't just machines of discovery, they are family.

Source of Article: Space.com 
By: Ian O'Neill, Discovery News 

2014년 1월 11일 토요일

Searching for Time Travelers, Scientists Look to Social Media

Time travelers, if they exist amongst us, have yet to betray their period-hopping ways online, according to a fun, new study aimed at finding visitors from another time, based on their digital footprints.

Theoretically, the idea of time travel forward in time should be possible according to Einstein's General Theory of Relativity. In fact, scientists have already sent teensy particles called muons forward in time. But sending a large object, such as an entire person, into the future remains in the echelons of science fiction, for now.

Even so, over a summer poker game, Robert Nemiroff, an astrophysicist at Michigan Technological University in Houghton, sparked an amusing discussion with his students by asking: If time travelers were living in our midst, would they leave traces of their presence online?

The researchers chose two recent events — the March 2013 election of Pope Francis to lead the Catholic Church, and the sungrazing Comet ISON, which was first spotted in September 2012 — to search for premature online references to time travelers. Perhaps careless time travelers made mention of Pope Francis or Comet ISON on Twitter or Facebook before they were supposed to know about them, the researchers said.
"The Internet is essentially a vast database, and I thought that if time travelers were here, their existence would have already come out in some other way, maybe by posting winning lottery numbers before they were selected," Nemiroff said in a statement.

Nemiroff and his students combed through results from search engines, such as Google and Bing, and social media sites, including Facebook and Twitter. Ultimately, their hunt came up empty.

"In our limited search we turned up nothing," Nemiroff said in a statement. "I didn't really think we would. But I'm still not aware of anyone undertaking a search like this."
The researchers did find one blog post that mentioned a "Pope Francis" before Jorge Mario Bergoglio, then-Archbishop of Buenos Aires, was elected to lead the Catholic Church, but they think the reference was accidental, rather than a message from a time-traveling visitor.
Nemiroff and his students even created their own special blog post in September 2013 that asked potential time travelers to email or tweet "#ICanChangeThePast2" or "#ICannotChangeThePast2" a month earlier, on or before August 2013. But, they again found no signs of time travel.

Still, Nemiroff, whose research typically covers more serious topics such as gravitational lensing and gamma-ray bursts, said the study, while focused on a seemingly far-out concept, was an enjoyable undertaking.

"I'm always doing stuff on space and time," he said. "This has been a lot of fun."
Nemiroff said the study was conducted during his students' own time, and without the use of any grant funding. The researchers presented their findings (or lack thereof) during a poster session Monday (Jan. 6) at the 223rd meeting of the American Astronomical Society in Washington, D.C.

Source of Article: Space.com
By: Denise Chow

2014년 1월 8일 수요일

Abundant 'Mini-Neptunes' Form New Class of Alien Planets

There's a new kind of planet to add to Kepler's cornucopia of alien worlds, and you won't find it in Earth's own solar system.

Ground-based follow-up observations of planets found by NASA's Kepler spacecraft reveal the masses and densities of 16 new planets ranging between one and four times the size of Earth. Many of the newfound orbs, described here today (Jan. 6) at a meeting of the American Astronomical Society, have a rocky core surrounded by a puffed-up envelope of gas, which scientists are calling "sub-Neptunes" or "mini-Neptunes."

"This marvelous avalanche of information about the sub-Neptunian planets is telling us about their core-envelope structure, not unlike a peach with its pit and fruit," study leader Geoff Marcy, a professor of astronomy at University of California, Berkeley, said in a statement.

Marcy and colleagues confirmed 41 of the planets discovered by Kepler, which spies the tiny dimming in starlight when a planet transits in front of its host star. The scientists used the ground-based telescopes at the Keck Observatory in Hawaii to measure the wobble of the host star as the planet exerts a slight gravitational tug on it.
Using this Doppler method, the team found the mass of 16 of the planets. Combining the planetary masses and their radii, inferred from the Kepler dimming data, the team determined the planets' densities, offering clues to whether they are rocky, gaseous or some hybrid of the two.

Five of the new planets are rocky, including Kepler-406b, a planet 1.4 times the radius of Earth that orbits its planet every 2.4 days.
But the majority of them appear to have a rocky core encased in a hydrogen- and helium-rich envelope. These kinds of mysterious planets don't exist in the solar system. The planets vary from having a puffy, thick envelope to having no envelope at all. The findings, published in the Astrophysical journal, confirm 38 new planets, six of which weren't seen by Kepler.

There's another way to determine the mass of a planet besides measuring the wobble of its host star. Neighboring planets gravitationally tug on each other, making one planet speed up in its orbit while the other slows down. By measuring variations in the timing of planetary transits, astronomers can figure out the mass.

Ji-Wei Xie of the University of Toronto and colleagues used this method to confirm 15 pairs of Kepler's planets between Earth-size and slightly larger than Neptune. The team reported the masses of these 30 planets in the Astrophysical Journal.

The primary objective of the Kepler mission is to determine the prevalence of Earth-like planets in the galaxy. To date, Kepler has identified more than 3,500 potential planets, including many orbiting in a habitable region around their stars. But whether they are rocky or could support alien life remains elusive.

The masses and densities of these newest planets start to answer these questions, allowing scientists to determine what fraction of stars harboring Earth-size planets in fact have rocky planets — which could hint at whether or not humans are alone.

Source of Article: Space.com
By: Tanya Lewis, Staff Writer

Newfound Earth-Mass Planet Is a Gassy Puffball

Astronomers have spotted a hotter and puffier version of Earth circling a distant star.
The oddball exoplanet candidate KOI-314c is located about 200 light-years away and is roughly the same mass as Earth, but its extremely thick atmosphere makes the world about 60 percent larger than our home planet, scientists say.

"This planet might have the same mass as Earth, but it is certainly not Earth-like," study lead author David Kipping, of the Harvard-Smithsonian Center for Astrophysics (CfA), said in a statement. "It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants."

Kipping announced the discovery of KOI-314c, which was made using observations by NASA's Kepler space telescope, today (Jan. 6) at the 223rd meeting of the American Astronomical Society in Washington.

Kepler was designed to spot exoplanets by noticing the telltale brightness dips they cause when crossing the face of, or transiting, their host stars' faces from the telescope's perspective. KOI-314c is the first transiting Earth-mass planet ever found and is the lightest alien world to have both its mass and size measured, researchers said.

The planet orbits its parent red dwarf star once every 23 days. The discovery team estimates KOI-314c's surface temperature to be 220 degrees Fahrenheit (104 degrees Celsius), meaning it's probably too hot to support life as we know it.

KOI-314c is likely surrounded by a hydrogen-helium atmosphere hundreds of miles thick, researchers said. This atmosphere may once have been even thicker, with much of it being boiled off into space over the eons by the red dwarf's radiation.

KOI-314c has a sibling planet called KOI-314b, which completes one orbit every 13 days. To calculate the mass of KOI-314c, the study team measured how the planet's gravity affects the movement of its neighbor world.

This technique, known as transit timing variations (TTV), is a departure from the usual method, in which astronomers measure the wobbles a planet's gravity induces in its parent star. TTV was first used successfully in 2010 but has a great deal of potential going forward, especially with regard to low-mass alien planets, researchers said.
"We are bringing transit timing variations to maturity," Kipping said.

Kipping and his team discovered KOI-314c by serendipity as they were poring over Kepler data looking for satellites of alien planets, known as exomoons.
"When we noticed this planet showed transit timing variations, the signature was clearly due to the other planet in the system and not a moon," Kipping said. "At first we were disappointed it wasn't a moon, but then we soon realized it was an extraordinary measurement."

Source of Article: Space.com
By: Mike Wall, Senior Writer

2014년 1월 7일 화요일

5 Rocky Alien Planets Revealed by NASA's Kepler Spacecraft

Five rocky planets are among a slew of newly discovered alien worlds found by NASA's prolific Kepler spacecraft. The planets, which range in size from ten to eighty percent larger than Earth, were announced Monday (Jan. 6) at the 223rd meeting of the American Astronomical Society in Washington, D.C.

Two of the newfound rocky planets, named Kepler-99b and Kepler-406b, are both 40 percent larger than Earth and have densities similar to lead, the researchers said. But, the chances of finding life on these exoplanets are slim, they added, since the two planets orbit their respective stars in less than five days, making these worlds sweltering and unable to support life as we know it.

Geoff Marcy, a professor of astronomy at the University of California, Berkeley, presented the findings, which included the masses and densities of 16 new planets — so-called mini-Neptunes — that are between one and four times the size of Earth.

"Kepler's primary objective is to determine the prevalence of planets of varying sizes and orbits," Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center in Moffett Field, Calif., said in a statement. "Of particular interest to the search for life is the prevalence of Earth-sized planets in the habitable zone. But the question in the back of our minds is: are all planets the size of Earth rocky? Might some be scaled-down versions of icy Neptunes or steamy water worlds? What fraction are recognizable as kin of our rocky, terrestrial globe?"

Source of Article: Space.com
By: Denise Chow, SPACE.com Staff Writer

Fast-Spinning Star Tests Einstein's General Relativity Theory

A unique triple-star system may help scientists resolve some of the gravitational conflicts behind general relativity and alternate theories of gravity.

A dense, fast-spinning star known as a millisecond pulsar closely orbits one white dwarf star, as the pair treks around a second white dwarf. The three stars are crammed into a region of space smaller than Earth's orbit around the sun.

"This is the first millisecond pulsar found in such a system, and we immediately recognized that it provides us a tremendous opportunity to study the effects of gravity," lead author Scott Ransom of the National Radio Astronomy Observatory (NRAO) said in a statement.

"This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work, and potentially for detecting problems with general relativity that physicists expect to see under extreme conditions," Ransom added.

A unique system

When a massive star explodes in a violent supernova, the remaining core can be transformed into a fast-spinning object known as a neutron star. These incredibly dense stars pack the mass of 1.4 suns into a space roughly the size of Washington, D.C.
If such a neutron star also spins, it is known as a pulsar; exceptionally fast-spinning stars are known as millisecond pulsars.

Lying 4,200 light-years from Earth, the millisecond pulsar PSR J0337+1715 spins 366 times per second, emitting radio waves much like a lighthouse emits visible light. The fast-spinning star was discovered in 2011 as part of a large-scale search for pulsars using the NRAO's Green Bank Telescope by graduate student Jason Boyles, then at West Virginia University. Scientists quickly realized that the pulsar was in orbit with two dead stars known as white dwarfs.

"The gravitational perturbations imposed on each member of this system by the others are incredibly pure and strong," Ransom said. "The millisecond pulsar serves as an extremely powerful tool for measuring those perturbations incredibly well."
Precision timing of the pulses from the spinning star allowed the scientists to compute details of the system.

"We have made some of the most accurate measurements of masses in astrophysics," study team member Anne Archibald, of the Netherlands Institute for Radio Astronomy, said in the same statement.

"Some of our measurements of the relative positions of the stars in the system are accurate to hundreds of meters," Archibald said.

The true nature of gravity

When Albert Einstein published his general theory of relativity in 1905, he defined gravity as a distortion of space-time by massive objects. But subsequent discoveries have led to attempts to develop a better understanding of the force.

The newly discovered triple system will allow scientists to study a violation of a concept known as the equivalence principle, which states that gravity's effects do not depend on the nature or internal structure of a body.

The most well-known example of this concept comes from the story wherein Italian astronomer Galileo Galilei reputedly dropped two balls of different masses from the top of the Leaning Tower of Pisa, though there is no historical conformation of the famous tale. In 1971, Apollo 15 Commander Dave Scott performed a similar experiment when he dropped a falcon feather and a hammer on the airless surface of the moon.
The same fast pulses that allowed Ransom's team to measure precisely the movement of the stars can also create a real-life gravitational laboratory.

When the remains of the massive progenitor star collapse into a neutron star, some of the mass is converted into gravitational binding energy that holds the super-dense star together. According to the strong equivalence principle, the binding energy will react gravitationally as mass, while the alternatives to general relativity say that it will not.
"This system offers the best test yet of which is the case," Ransom said.

If Einstein's theory is correct in all cases, the gravitational effect of the outer white dwarf would be identical for both the inner white dwarf and the neutron star. But if the strong equivalence principle is invalid, the outer star's gravitational effects on the inner system would be slightly different for each star.

High-precision timing of the pulses would allow scientists to test for deviations from the strong equivalence principle far more precisely than has ever been possible, a deviation that would lead to a greater understanding of gravity, researchers said.

"This is a fascinating system in many ways, including what must have been a completely crazy formation history, and we have much work to do to fully understand it," Ransom said.

Source of Article: Space.com
By: Nola Taylor Redd, SPACE.com Contributor

Storms on 'Failed Stars' Rain Molten Iron

 Violent storm clouds and molten-iron rain may be common occurrences on the failed stars known as brown dwarfs, new research suggests.

Astronomers used NASA's infrared Spitzer Space Telescope to observe brown dwarfs, finding changes in brightness that they believe signify the presence of storm clouds. These storms appear to last at least several hours, and may be as tempestuous as the famous Great Red Spot on Jupiter.

"A large fraction of brown dwarfs show cyclical variability in brightness, suggesting clouds or storms," study researcher Aren Heinze of Stony Brook University said in a news conference here today (Jan. 7) at the 223rd meeting of the American Astronomical Society.

Brown dwarfs are cool, star-like objects that don't have enough mass to fuse hydrogen into helium, the main energy source for stars. They can be considered the giant cousins of planets like Jupiter.

Heinze and his colleagues measured the brightness of 44 brown dwarfs for up to 20 hours, as part of Spitzer's "Weather on Other Worlds" program.

Previous research suggested that brown dwarfs had stormy weather 5 to 10 percent of the time, so the scientists expected to see some variation in brightness. But surprisingly, almost half of the brown dwarfs observed showed such variation. Taking into account the fact that about half of the brown dwarfs are oriented such that storms are hidden, or simply unchanging, the data suggest that turbulent storms on brown dwarfs are common.

"We're talking about cloud masses larger than the Earth forming and dissipating over the timescale of just a few hours in some of these objects," Heinze told SPACE.com.
These clouds are much too hot to be composed of water. Instead, astronomers believe they are made up of sand and molten iron.

Spitzer monitored the storms for less than a day, so astronomers don't know whether the storms persist for months or years, like Jupiter's Great Red Spot. In some cases, the storms are clearly dynamic and rapidly changing, Heinze said.

The brightness observations were only possible because Spitzer is above Earth's atmosphere, where our planet's glowing heat doesn't obscure them.

Another surprise from Spitzer's observations was how slowly the brown dwarfs rotated. Conventional thinking held that brown dwarfs spin quickly when they form and contract, without slowing down as the orbs age. The team doesn't know why the brown dwarfs spin so slowly. They may have formed in an unusual way, or they may be dragged by gravity from an unknown closely orbiting planet.

Studying weather on brown dwarfs could widen scientists' understanding of weather on giant planets outside the solar system, which are harder to see because of the glare of their host stars, researchers said.

Source of Article: Space.com
By: Tanya Lewis, Staff Writer