A Planet As Big As Its Star

Image Credit: NASA/JPL

Source and Credit: PlanetQuest (NASA/JPL)

A long-proposed tool for hunting planets has netted its first catch -- a Jupiter-like planet orbiting one of the smallest stars known.

The technique, called astrometry, was first attempted 50 years ago to search for planets outside our solar system, called exoplanets. It involves measuring the precise motions of a star on the sky as an unseen planet tugs the star back and forth. But the method requires very precise measurements over long periods of time, and until now, has failed to turn up any exoplanets.

A team of two astronomers from NASA's Jet Propulsion Laboratory, Pasadena, Calif., has, for the past 12 years, been mounting an astrometry instrument to a telescope at the Palomar Observatory near San Diego. After careful, intermittent observations of 30 stars, the team has identified a new exoplanet around one of them -- the first ever to be discovered around a star using astrometry.

"This method is optimal for finding solar-system configurations like ours that might harbor other Earths," said astronomer Steven Pravdo of JPL, lead author of a study about the results to be published in the Astrophysical Journal. "We found a Jupiter-like planet at around the same relative place as our Jupiter, only around a much smaller star. It's possible this star also has inner rocky planets. And since more than seven out of 10 stars are small like this one, this could mean planets are more common than we thought."

The finding confirms that astrometry could be a powerful planet-hunting technique for both ground- and space-based telescopes. For example, a similar technique would be used by SIM Lite, a NASA concept for a space-based mission that is currently being explored.

The newfound exoplanet, called VB 10b, is about 20 light-years away in the constellation Aquila. It is a gas giant, with a mass six times that of Jupiter's, and an orbit far enough away from its star to be labeled a "cold Jupiter" similar to our own. In reality, the planet's own internal heat would give it an Earth-like temperature.

The planet's star, called VB 10, is tiny. It is what's known as an M-dwarf and is only one-twelfth the mass of our sun, just barely big enough to fuse atoms at its core and shine with starlight. For years, VB 10 was the smallest star known -- now it has a new title: the smallest star known to host a planet. In fact, though the star is more massive than the newfound planet, the two bodies would have a similar girth.

Because the star is so small, its planetary system would be a miniature, scaled-down version of our own. For example, VB 10b, though considered a cold Jupiter, is located about as far from its star as Mercury is from the sun. Any rocky Earth-size planets that might happen to be in the neighborhood would lie even closer in.

"Some other exoplanets around larger M-dwarf stars are also similar to our Jupiter, making the stars fertile ground for future Earth searches," said Stuart Shaklan, Pravdo's co-author and the SIM Lite instrument scientist at JPL. "Astrometry is best suited to find cold Jupiters around all kinds of stars, and thus to find more planetary systems arranged like our home."

Two to six times a year, for the past 12 years, Pravdo and Shaklan have bolted their Stellar Planet Survey instrument onto Palomar's five-meter Hale telescope to search for planets. The instrument, which has a 16-megapixel charge-coupled device, or CCD, can detect very minute changes in the positions of stars. The VB 10b planet, for instance, causes its star to wobble a small fraction of a degree. Detecting this wobble is equivalent to measuring the width of a human hair from about three kilometers away.

Other ground-based planet-hunting techniques in wide use include radial velocity and the transit method. Like astrometry, radial velocity detects the wobble of a star, but it measures Doppler shifts in the star's light caused by motion toward and away from us. The transit method looks for dips in a star's brightness as orbiting planets pass by and block the light. NASA's space-based Kepler mission, which began searching for planets on May 12, will use the transit method to look for Earth-like worlds around stars similar to the sun.

"This is an exciting discovery because it shows that planets can be found around extremely light-weight stars," said Wesley Traub, the chief scientist for NASA's Exoplanet Exploration Program at JPL. "This is a hint that nature likes to form planets, even around stars very different from the sun."

Life 4.4 Billion Years Ago?

Image Credit:  NASA/JPL

Source and Credit:  UC-Boulder

The bombardment of Earth nearly 4 billion years ago by asteroids as large as Kansas would not have had the firepower to extinguish potential early life on the planet and may even have given it a boost, says a new University of Colorado at Boulder study.

Impact evidence from lunar samples, meteorites and the pockmarked surfaces of the inner planets paints a picture of a violent environment in the solar system during the Hadean Eon 4.5 to 3.8 billion years ago, particularly through a cataclysmic event known as the Late Heavy Bombardment about 3.9 million years ago. Although many believe the bombardment would have sterilized Earth, the new study shows it would have melted only a fraction of Earth's crust, and that microbes could well have survived in subsurface habitats, insulated from the destruction.

"These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago," said CU-Boulder Research Associate Oleg Abramov. "It opens up the possibility that life emerged as far back as 4.4 billion years ago, about the time the first oceans are thought to have formed."

A paper on the subject by Abramov and CU-Boulder geological sciences Professor Stephen Mojzsis appears in the May 21 issue of Nature.

Because physical evidence of Earth's early bombardment has been erased by weathering and plate tectonics over the eons, the researchers used data from Apollo moon rocks, impact records from the moon, Mars and Mercury, and previous theoretical studies to build three-dimensional computer models that replicate the bombardment. Abramov and Mojzsis plugged in asteroid size, frequency and distribution estimates into their simulations to chart the damage to the Earth during the Late Heavy Bombardment, which is thought to have lasted for 20 million to 200 million years.

The 3-D models allowed Abramov and Mojzsis to monitor temperatures beneath individual craters to assess heating and cooling of the crust following large impacts in order to evaluate habitability, said Abramov. The study indicated that less than 25 percent of Earth's crust would have melted during such a bombardment.

The CU-Boulder researchers even cranked up the intensity of the asteroid barrage in their simulations by 10-fold -- an event that could have vaporized Earth's oceans. "Even under the most extreme conditions we imposed, Earth would not have been completely sterilized by the bombardment," said Abramov.

Instead, hydrothermal vents may have provided sanctuaries for extreme, heat-loving microbes known as "hyperthermophilic bacteria" following bombardments, said Mojzsis. Even if life had not emerged by 3.9 billion years ago, such underground havens could still have provided a "crucible" for life's origin on Earth, Mojzsis said.

The researchers concluded subterranean microbes living at temperatures ranging from 175 degrees to 230 degrees Fahrenheit would have flourished during the Late Heavy Bombardment. The models indicate that underground habitats for such microbes increased in volume and duration as a result of the massive impacts. Some extreme microbial species on Earth today -- including so-called "unboilable bugs" discovered in hydrothermal vents in Yellowstone National Park -- thrive at 250 F.

Geologic evidence suggests that life on Earth was present at least 3.83 billion years ago, said Mojzsis. "So it is not unreasonable to suggest there was life on Earth before 3.9 billion years ago. We know from the geochemical record that our planet was eminently habitable by that time, and this new study sews up a major problem in origins of life studies by sweeping away the necessity for multiple origins of life on Earth."

Most planetary scientists believe a rogue planet as large as Mars smacked Earth with a glancing blow 4.5 billion years ago, vaporizing itself and part of Earth. The collision would have created an immense vapor cloud from which moonlets, and later our moon, coalesced, Mojzsis said. "That event, which preceded the Late Heavy Bombardment by at least 500 million years, would have effectively hit Earth's re-set button," he said.

"But our results strongly suggest that no events since the moon formation were capable of destroying Earth's crust and wiping out any biosphere that was present," Mojzsis said. "Instead of chopping down the tree of life, our view is that the bombardment pruned it."

The results also support the potential for microbial life on other planets like Mars and perhaps even rocky, Earth-like planets in other solar systems that may have been resurfaced by impacts, said Abramov.

"Exactly when life originated on Earth is a hotly debated topic," says NASA's Astrobiology Discipline Scientist Michael H. New, manager of the Exobiology and Evolutionary Biology program. "These findings are significant because they indicate life could have begun well before the Late Heavy Bombardment, during the so-called Hadean Eon of Earth's history 3.8 billion to 4.5 billion years ago."

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Read the full article at New Scientist.

Kepler's Planet Hunt Begins

Image Credit:  NASA/JPL

Source and Credit:  NASA/JPL

NASA's Kepler spacecraft has begun its search for other Earth-like worlds. The mission, which launched from Cape Canaveral, Fla., on March 6, will spend the next three-and-a-half years staring at more than 100,000 stars for telltale signs of planets. Kepler has the unique ability to find planets as small as Earth that orbit sun-like stars at distances where temperatures are right for possible lakes and oceans. 

"Now the fun begins," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "We are all really excited to start sorting through the data and discovering the planets." 

Scientists and engineers have spent the last two months checking out and calibrating the Kepler spacecraft. Data have been collected to characterize the imaging performance as well as the noise level in the measurement electronics. The scientists have constructed the list of targets for the start of the planet search, and this information has been loaded onto the spacecraft. 

"If Kepler got into a staring contest, it would win," said James Fanson, Kepler project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The spacecraft is ready to stare intently at the same stars for several years so that it can precisely measure the slightest changes in their brightness caused by planets." Kepler will hunt for planets by looking for periodic dips in the brightness of stars -- events that occur when orbiting planets cross in front of their stars and partially block the light. 

The mission's first finds are expected to be large, gas planets situated close to their stars. Such discoveries could be announced as early as next year. 

Kepler is a NASA Discovery mission. NASA Ames Research Center, Moffett Field, Calif., is the home organization of the science principal investigator, and is responsible for the ground system development, mission operations and science data analysis. JPL manages the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., is responsible for developing the Kepler flight system and supporting mission operations. 

For more information about the Kepler mission, visit: http://www.nasa.gov/kepler and http://www.kepler.nasa.gov .

First Optical SETI Detection?

From a recent article in The Australian:

AFTER you've spent more than 20 years hunting for an alien signal, you think you'd be celebrating if you noticed a mysterious pulse suddenly rising up on your computer readouts. A regular pulse, amid the random clatter of the cosmos, suggests that someone very smart at the other end is sending a message.

But when Ragbir Bhathal, an astrophysicist at the University of Western Sydney, who teaches the only university-based course on SETI (search for extraterrestrial intelligence) in Australia, detected the suspicious signal on a clear night last December, he knew better than to crack open the special bottle of champagne he has tucked away for the history-making occasion.

Instead, he's spent the past few months meticulously investigating whether the unrecognised signature was caused by a glitch in his instrumentation, a rogue astrophysical phenomenon, or some unknown random noise.

Even if he picks up the signal again - he's been scouring the same co-ordinates of the night sky on an almost daily basis since - the scientific rule book dictates he'll need to get it peer-reviewed before he can take his announcement to the world. "And that is a lot of ifs," he concedes.

Has Bhathal made the first detection of an advanced technological civilization from an extrasolar planetary system?  

According to the article, Bhathal's OZ OSETI program is an optical SETI program searching for extraterrestrial laser bursts.  The only optical SETI program in Earth's southern hemisphere, OZ OSETI searches out to 100 light-years -- an area large enough to contain at least 1000 stars and perhaps 20 times as many planets.

Which could mean -- if Bhathal finds that elusive signal again -- our first confirmed galactic neighbor may be closer than many predicted.

Astro-Comb To Hunt Planets

Artist's impression of an exoplanet.  Credit:  ESO

Source and Credit:  Optical Society of America, via EurekAlert!

Thanks to the ability of astronomers to detect the presence of extrasolar planets orbiting distant stars, scientists today are able to examine hundreds of solar systems. Now researchers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. have created an "astro-comb" to help astronomers detect lighter planets, more like Earth, around distant stars.

In most cases, extrasolar planets can't be seen directly—the glare of the nearby star is too great—but their influence can be discerned through spectroscopy, which analyzes the energy spectrum of the light coming from the star. Not only does spectroscopy reveal the identity of the atoms in the star (each element emits light at a certain characteristic frequency), it can also tell researchers how fast the star is moving away or toward Earth, courtesy of the Doppler effect, which occurs whenever a source of waves is itself in motion. By recording the change in the frequency of the waves coming from or bouncing off of an object, scientists can deduce the velocity of the object.

This process is used to judge the speed of automobiles, storm systems, fastballs, and stars. How can it be used to deduce the presence of a planet? Though the planet might weigh millions of times less than the star, the star will be jerked around a tiny amount owing to the gravity interaction between star and planet. This jerking motion causes the star to move toward or away from Earth slightly in a way that depends on the planet's mass and its nearness to the star. The better the spectroscopy used in this whole process, the better will be the identification of the planet in the first place and the better will be the determination of planetary properties.

Right now standard spectroscopy techniques can determine star movements to within a few meters per second (m/sec). In tests, the Harvard researchers are now able to calculate star velocity shifts of less than 1 m/sec, allowing them to more accurately pinpoint the planet's location.

Smithsonian researcher David Phillips says that he and his colleagues expect to reach a velocity resolution of 60 cm/sec, and maybe even 1 cm/sec, which when applied to the activities of large telescopes presently under construction, would open new possibilities in astronomy and astrophysics, including simpler detection of more Earth-like planets.

With this new approach, Harvard astronomers achieve their great improvement using a frequency comb as the basis for the astro-comb. A special laser system is used to emit light not at a single energy but a series of energies (or frequencies), evenly spaced across a wide range of values. A plot of these narrowly-confined energy components would look like the teeth of a comb, hence the name frequency comb. The energy of these comb-like laser pulses is known so well that they can be used to calibrate the energy of light coming in from the distant star. In effect, the frequency comb approach sharpens the spectroscopy process. The resultant astro-comb should enable a further expansion of extrasolar planetary detection.

The astro-comb method has been tried out on a medium-sized telescope in Arizona and will soon be installed on the much larger William Herschel Telescope, which resides on a mountaintop in the Canary Islands.

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More here from New Scientist.

Warp Speed Possible

Source and Credit:  Baylor University

Two Baylor University scientists have come up with a new method to cause a spaceship to effectively travel faster than the speed of light, without breaking the laws of physics.

Dr. Gerald Cleaver, associate professor of physics at Baylor, and Richard Obousy, a Baylor graduate student, theorize that by manipulating the extra spatial dimensions of string theory around a spaceship with an extremely large amount of energy, it would create a "bubble" that could cause the ship to travel faster than the speed of light. To create this bubble, the Baylor physicists believe manipulating the 10th spatial dimension would alter the dark energy in three large spatial dimensions: height, width and length. Cleaver said positive dark energy is currently responsible for speeding up the expansion rate of our universe as time moves on, just like it did after the Big Bang, when the universe expanded much faster than the speed of light for a very brief time.

"Think of it like a surfer riding a wave," said Cleaver, who co-authored the paper with Obousy about the new method. "The ship would be pushed by the spatial bubble and the bubble would be traveling faster than the speed of light."

The method is based on the Alcubierre drive, which proposes expanding the fabric of space behind a ship and shrinking space-time in front of the ship. The ship would not actually move, rather the ship would sit in a bubble between the expanding and shrinking space-time dimensions. Since space would move around the ship, the theory does not violate Einstein's Theory of Relativity, which states that it would take an infinite amount of energy to accelerate a massive object to the speed of light.

String theory suggests the universe is made up of multiple dimensions. Height, width and length are three dimensions, and time is the fourth dimension. String theorists use to believe that there were a total of 10 dimensions, with six other dimensions that we can not yet identify because of their incredibly small size. A new theory, called M-theory, takes string theory one step farther and states that the "strings" that all things are made of actually vibrate in an additional spatial dimensional, which is called the 10th dimension. It is by changing the size of this 10th spatial dimension that Baylor researchers believe could alter the strength of the dark energy in such a manner to propel a ship faster than the speed of light.

The Baylor physicists estimate that the amount of energy needed to influence the extra dimension is equivalent to the entire mass of Jupiter being converted into pure energy for a ship measuring roughly 10 meters by 10 meters by 10 meters.

"That is an enormous amount of energy," Cleaver said. "We are still a very long ways off before we could create something to harness that type of energy."

The paper appears in the Journal of the British Interplanetary Society.

The full paper can be viewed here.

 

Dead Suns, Dead Planets

Image Credit: NASA/JPL-Caltech

Source and Credit:  Royal Astronomical Society

Using NASA’s Spitzer Space Telescope, an international team of astronomers have found that at least 1 in 100 white dwarf stars show evidence of orbiting asteroids and rocky planets, suggesting these objects once hosted Solar Systems similar to our own.

White dwarf stars are the compact, hot remnants left behind when stars like our Sun reach the end of their lives. Their atmospheres should consist entirely of hydrogen and helium but are sometimes found to be contaminated with heavier elements like calcium and magnesium. The new observations suggest that these Earth-sized stars are often polluted by a gradual rain of closely orbiting dust that emits infrared radiation picked up by Spitzer.

The data suggest that at least 1% to 3% of white dwarf stars are contaminated in this way and that the dust originates from rocky bodies like asteroids (also known as minor planets). In our Solar System, minor planets are the left over building blocks of the rocky terrestrial planets like the Earth. The Spitzer results imply that asteroids are found in orbit around a large number of white dwarfs, perhaps as many as 5 million in our own Milky Way Galaxy.

The new findings indicate the dust is completely contained within the Roche limit of the star -- close enough that any object larger than a few kilometres would be ripped apart by gravitational tides (the same phenomenon which led to the creation of Saturn's rings).  This backs up the team’s hypothesis that the dust disks around white dwarfs are produced by tidally disrupted minor planets.  In order to pass this close to the white dwarf, an asteroid must be perturbed from its regular orbit further out – and this can occur during a close encounter with as yet unseen planets.

Because white dwarfs descend from main sequence stars like the Sun, the team’s work implies that at least 1% to 3% of main sequence stars have terrestrial planets around them. Dr Farihi comments. “In the quest for Earth-like planets, we have now identified numerous systems which are excellent candidates to harbour them. Where they persist at white dwarfs, any terrestrial planets will likely not be habitable, but may have been sites where life developed during a previous epoch. “

Perhaps the most exciting and important aspect of this research is that the composition of these crushed asteroids can be measured using the heavy elements seen in the white dwarf.

Dr Farihi sees this as a crucial step forward. “With high quality optical and ultraviolet observations (e.g. the Hubble Space Telescope), we should be able to measure up to two dozen different elements in debris-polluted white dwarfs.  We can then address the question, “Are the rocky extrasolar planets we find similar to the terrestrial planets of our Solar System?”

Comets Made Life Possible

Source and Credit:  Tel Aviv University

Comets have always fascinated us. In early cultures, a mysterious appearance of a comet could symbolize a deity's displeasure with humankind or mean a sure failure in battle, at least for one side. Now Tel Aviv University research adds a new twist to that fascination: comets might have provided the elements for the emergence of life on our planet.

While investigating the chemical make-up of comets, Prof. Akiva Bar-Nun of the Department of Geophysics and Planetary Sciences at Tel Aviv University found they were the source of missing ingredients needed for life in Earth's ancient primordial soup. "When comets slammed into the Earth through the atmosphere about four billion years ago, they delivered a payload of organic materials to the young Earth, adding materials that combined with Earth's own large reservoir of organics and led to the emergence of life," says Prof. Bar-Nun.

It was the chemical composition of comets, Prof. Bar-Nun believes, that allowed them to kickstart life. He has published his theory widely in scientific journals, including recently in the journal Icarus.

A Pinch of Argon, A Dash of Xenon

Using a one-of-a-kind machine built at Tel Aviv University, researchers were able to simulate comet ice, and found that comets contain ingredients necessary for providing the basic nutrients of life.

Specifically, Prof. Bar-Nun looked at the noble gases Argon, Krypton and Xenon, because they do not interact with any other elements and are not destroyed by Earth's oxygen. These elements have maintained stable proportions in the Earth's atmosphere throughout the lifetime of the planet, he explains.

"Now if we look at these elements in the atmosphere of the Earth and in meteorites, we see that neither is identical to the ratio in the sun's composition. Moreover, the ratios in the atmosphere are vastly different than the ratios in meteorites which make up the bulk of the Earth. So we need another source of noble gases which, when added to these meteorites or asteroid influx, could change the ratio. And this came from comets.

Solving the Otherworldly Puzzle

Comets are essentially large chunks of ice, whose temperature ranges from -200 to -250 degrees centigrade. Formed in the early days of the solar system far away from the sun, water vapor condensed directly into ice, making little grains. These grains came together to form the comets, which are less than 2/3 of a mile in diameter, explains Prof. Bar-Nun.

During the comets' formation, the porous ice trapped gases and organic chemicals that were present in outer space. "The pattern of trapping of noble gases in the ice gives a certain ratio of Argon to Krypton to Xenon, and this ratio — together with the ratio of gases that come from rocky bodies — gives us the ratio that we observe in the atmosphere of the Earth."

Thus, the arrival on Earth of comets and asteroids led to the necessary ratio of materials for organic life, "which eventually were dissolved in the ocean and started the long process leading to the emergence of life on Earth," says Prof. Bar-Nun.

Asteroid Showers and Thunderstorms

The story started between 4.6 and 3.8 billion years ago, when both the moon and the Earth were bombarded by a flux of asteroids and comets. "On the Earth, most of the craters were obliterated by continental movement and by weathering winds and water erosion. On the moon, they remained as they were," says Prof. Bar-Nun, who adds that no life could thrive during this period of bombardment.

But the Earth recovered, and three to four hundred million years later, fragile forms of life emerged after the comet-delivered elements precipitated into the ocean. "There was another chemical development of these molecules in water, which became more and more complex," says Prof. Bar-Nun, leading to the origin of life on Earth.

Thought-Controlled Robotic Wheelchair

Paralyzed people may soon be able to drive motorized wheelchairs controlled by a combination of mind-reading computers and autonomous software.  

Full story from New Scientist.

Invisibility Cloak Becomes Reality

Source and Credit:  DOE/Lawrence Berkeley National Laboratory

The great science fiction writer Arthur C. Clarke famously noted the similarities between advanced technology and magic. This summer on the big screen, the young wizard Harry Potter will once again don his magic invisibility cloak and disappear. Meanwhile, researchers with Berkeley Lab and the University of California (UC) Berkeley will be studying an invisibility cloak of their own that also hides objects from view.

A team led by Xiang Zhang, a principal investigator with Berkeley Lab’s Materials Sciences Division and director of UC Berkeley’s Nano-scale Science and Engineering Center, has created a “carpet cloak” from nanostructured silicon that conceals the presence of objects placed under it from optical detection. While the carpet itself can still be seen, the bulge of the object underneath it disappears from view. Shining a beam of light on the bulge shows a reflection identical to that of a beam reflected from a flat surface, meaning the object itself has essentially been rendered invisible.

“We have come up with a new solution to the problem of invisibility based on the use of dielectric (nonconducting) materials,” says Zhang. “Our optical cloak not only suggests that true invisibility materials are within reach, it also represents a major step towards transformation optics, opening the door to manipulating light at will for the creation of powerful new microscopes and faster computers.”

Zhang and his team have published a paper on this research in the journal Nature Materials entitled: An Optical Cloak Made of Dielectrics. Co-authoring the paper with Zhang were Jason Valentine, Jensen Li, Thomas Zentgraf and Guy Bartal, all members of Zhang’s research group.

Get the full story here.

History Of The Drake Equation

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