Topic: Astrography, Subject: Planetary Bodies
A new planet that's a real diamond
12 OCTOBER 2012 Sci/Tech
Source: News 4
It seems the universe has just got a little bit richer following the discovery of a new planet which scientists say is made largely out of diamonds.
The rocky planet called '55 Cancri e' orbits a sun-like star in the constellation of Cancer and is twice the size of Earth.
Time is said to move at hyper-speed on this gem-like planet so one year lasts just 18 hours compared to Earth's 365 days.
Despite being 40 light years away from earth, in dark skies 55 Cancri e's host star is clearly visible to the naked eye.
Researchers believe the planet's surface is covered primarily in carbon in the form of graphite and diamond rather than water and granite like our planet.
Marek Kukula, Public Astronomer at the Royal Observatory Greenwich told Channel 4 News, "It's a lovely image - diamonds in the sky - but there's not likely to be a space mission to the mine the diamonds any time soon because it would probably take 10,000 years to get there.
Buried deep down
"The planet is intensely hot, 2,000 degrees Centigrade and the diamonds are likely to be buried deep down. We'd end up spending all the diamonds on Earth in order to get there so it's not a way to get rich quick.
"In general mining in space is being talked about more and more and is moving away from being something science-fiction to something that is more serious. Asteroids are thought to have precious metals and they are relatively close to us in our solar system.
"Although they are moving, if we could chase and catch one it is not far-fetched to think in the next couple of decades this may be tested."
The study was led by researchers at Yale University who estimate that at least one third of the 55 Cancri e's mass - the equivalent of about three earth masses - could be diamond.
It's the first time astronomers have identified a diamond planet around a sun-like star and specified its chemical make-up. David Spergel, an astronomer at Princeton University, said it was relatively simple to work out the basic structure and history of a star once you know its mass and age.
He said: "Planets are much more complex. This 'diamond-rich super-Earth' is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars."
Topic: Astrography, Subject: Binary Star Systems
Many Planets Could Circle Twin Suns, NASA Says
Victoria Jaggard
from
National Geographic News
March 30, 2007
"But I was going into Toshi Station to pick up some power converters."
If life exists on other worlds, someone could be whining about doing their chores on a planet not unlike Star Wars's Tatooine. The latest data from NASA's Spitzer Space Telescope suggests that the universe might be brimming with planets that have two suns like the desert world that Luke Skywalker called home (see related images from Spitzer). More than half of all known star systems are binaries, with twin stars locked in a gravitational dance, NASA scientists say. The new data show that dusty disks of debris that could be indicators of planet formation are just as abundant around binaries as they are around single stars. "There could be countless planets out there with two or more suns," lead study author David Trilling of the University of Arizona, Tucson, said in a press release. Trilling and colleagues will publish a paper on their research in the April 1 issue of the Astrophysical Journal.
Twin Suns
Existing techniques for looking directly for planets don't work very well when searching around binary stars. Normally, planet hunters look for the so-called Doppler wobble as evidence of a planet's gravity tugging on its host star. "But everything in a binary system is more complicated," Trilling told National Geographic News. That's because, in addition to any planets in orbit, both stars are tugging on each other, he said. Each star's effect on the other would be great enough to mask the planet's effect.
So Trilling's team used Spitzer's infrared cameras to scan for planetary disks instead.
"Spitzer is very good at detecting emitted thermal radiation from dust," Trilling said. "When we're searching for the dust disks, we're looking at a wavelength at which the stars are faint but the dust is bright." Of the 69 binary systems the team studied, 40 percent were shown to have these dusty disks, meaning they could very well have planets in orbit.
Tatooine Plausible
Astronomers had previously found that planetary disks exist in binary systems where the twin stars are very far apart from each other—about a hundred times farther apart than the distance between Earth and the sun. Nearly 200 planets outside our solar system have been discovered so far with the wobble technique. About a quarter orbit one star in a binary system (related: "Many 'Earths' Are Out There, Study Says." The latest project focused on binary stars that are much closer together—less than 500 times the distance between Earth and the sun. What really astonished astronomers was that 60 percent of the tightly circling twin stars they saw had dusty disks—a setup that could create a scene like the Tatooine sunset in Star Wars. This finding actually makes perfect sense, said Alan P. Boss, an expert in planet formation at the Carnegie Institution in Washington, D.C. "The close binary appears to be pretty much a single, massive star to the material in orbit around it that is trying to form a planetary system," Boss said in an email interview. And "if the planetary orbits are stable and at a distance where liquid water is possible, then they will be habitable." If planets are in the dusty disks spied by Spitzer, there's no reason some of them couldn't support life, study author Trilling said. "I've been thinking about it, and there's nothing astronomically wrong with that picture," he noted, referring to the famous movie still. "But it is still science fiction—there's no reason to believe it really exists."
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Topic: Astrography, Subject: Binary Star Systems - Kapler 16b
My 2 Suns: Bounty of New Exoplanet Discoveries Includes a World Orbiting a Binary Star
By Rachel Kaufman
from
Scientific American
September 15, 2011
Leading planet hunters from around the world announced the discovery of some 75 extrasolar planets, and hints of many more
The hundreds of distant worlds, some large and some small, that are known to dot the galaxy provide plenty of intrigue for the scientists who hunt them. But the catalogued planetary population has just gotten a lot larger and more diverse, thanks to word this week of a newly identified planet orbiting two suns, more than a dozen newfound "super-Earths," and strong indications that the Milky Way Galaxy is home to an almost unfathomable number of planets awaiting discovery.
More than 350 researchers from around the globe gathered at the Extreme Solar Systems (ESS) II conference in Grand Teton National Park, Wyo., to share their findings on these newfound exoplanets, or planets outside our solar system, of every size and configuration.
The most exotic of the latest batch of exoplanets is the world with two suns, like Tatooine of Star Wars or Dr. Who's Gallifrey. The planet, named Kepler 16 b for the NASA Kepler spacecraft that spotted it, revolves around two stars locked in a tight binary pairing; the planet's wide, nearly circular orbit keeps it well outside the stars' orbital dance. The trio is not the only so-called circumbinary system known, but it is the first for which researchers have been able to measure the properties of both stars and the planet so precisely, and the first system where the planet has been directly detected, rather than inferred. [Read more about other planets Kepler has found.]
The researchers, led by Laurance Doyle of the SETI Institute in Mountain View, Calif., announced the finding at the ESS conference and with a September 15 press conference in California that included a visual-effects supervisor from Lucasfilm, the makers of Star Wars. Doyle, Joshua Carter of the Harvard–Smithsonian Center for Astrophysics (CfA), and their colleagues also described the Kepler 16 system in a study in the September 16 issue of Science.
Kepler 16 b is reminiscent of Saturn in its dimensions and mass, but slightly denser, implying that its makeup skews more to elements heavier than hydrogen and helium. The giant planet orbits its parent stars every 229 Earth days. As curious as Kepler 16 b is, the stellar binary that hosts it is noteworthy as well. The smaller of the two stars is just one fifth the mass of our sun, making it the smallest main-sequence star whose physical properties are well known.
"We thought we understood stellar evolution for a long time, but when you get to the end of the main sequence," the data do not fit the models, Doyle says. "Now any kind of excuse of 'you’re not measuring very well' goes out the window. This one, we nailed."
The astronomical oddball was not the only news from the Kepler mission at the ESS meeting. Sarah Ballard, a CfA graduate student and member of the Kepler team, described on September 12 a newly uncovered pair of planets orbiting the star Kepler 19.
Kepler 19 b, only twice as Earth's diameter, is among the smallest exoplanets knownto date. But it is likely a miserable place: at just 13.5 million kilometers from its host star, the planet's surface is likely a toasty 480 degrees Celsius.
The Kepler spacecraft detects planets such as Kepler 19 b by watching them dim the light of their host star as the planets pass in front, or "transit." Ordinarily, those transits will occur at regular intervals, like celestial clockwork, but oddities in Kepler 19 b's transit times suggest the influence of the other half of the pair—a larger, unseen planet also orbiting Kepler 19 and perturbing the motion of its neighbor.
"This is uncharted waters," Ballard says. This is the first time that anomalies in the occurrence times of transits have been used to make a solid claim for the discovery of an alien world, she says. The unseen planet, Kepler 19 c, is still mysterious, Ballard notes, adding that it "could be a rocky planet on a five-day orbit, or it could be a gas giant on an oblong, 100-day orbit."
Kepler is hardly the only planet-finding campaign meeting with success and making news this week at the Wyoming confab. A search based at institutions in the U.K. and Spain, the Wide-Angle Search for Planets (WASP), reported the discovery of some two dozen new planets. And a European contingent from the High Accuracy Radial velocity Planet Searcher (HARPS) had an even bigger haul to unveil.
There seem to be plenty of targets to go around: most of the tens of billions of yellow-orange stars in the galaxy might harbor planets, new HARPS data suggest. Previous HARPS results had implied that up to half of these stars could have planets, but a new statistical analysis shows the percentage to be even higher, about 70 percent, Francesco Pepe of the Observatory of Geneva in Switzerland said during a press conference announcing the HARPS results on September 12.
The HARPS team announced about 50 new planets, of which 16 are super-Earths—planets larger than our own but smaller than Neptune or Uranus. Statistical models suggest that four in 10 stars harbor super-Earths. One of the newfound HARPS planets, HD 85512 b, orbits on the edge of the habitable zone, a temperate band surrounding a star where temperatures could support liquid water and just maybe extraterrestrial life.
HARPS is an instrument that measures the wobble caused by a planet's gravitational tug on its host star, so it can be used to estimate planetary mass. It is not able to measure the diameter of planets, so these "super-Earths" could be large and gaseous, like Neptune, or small and rocky, like Earth, the researchers say.
Studying super-Earths is a particularly fruitful area of planetary science, says David Latham of the CfA, who was not involved in the HARPS work. "It's a kind of planet we don't have in our own system," he says. In fact, the existence of super-Earths has come to light only in the past few years.
Between the super-Earths, the circumbinary planet, and the dozens of other new discoveries, researchers are now turning up exoplanets in unprecedented numbers. "We are really in the age of discovery of new worlds," said Lisa Kaltenegger of the Max Planck Institute for Astronomy in Heidelberg, Germany, and the CfA during the press conference.
Topic: Astrography, Subject: Hot Planets
"Hot Jupiters" Could Give Rise to Earthlike Worlds, Study Says
Anne Minard
for
National Geographic News
September 7, 2006
It's more likely than ever that we are not alone in the universe, new research suggests. The latest computer models are telling scientists that more than a third of the star systems containing Jupiterlike gas giants may also harbor Earthlike planets. These so-called habitable exoplanets could be awash in oceans of liquid water, which means they might support life. The latest work focuses on a type of star system that contains gas giants known as hot Jupiters. Unlike gas giants in our solar system, hot Jupiters have orbits that swing tightly around their stars, says Sean Raymond, study co-author and astrophysicist at the University of Colorado in Boulder. Scientists believe that hot Jupiters initially form far from their host stars. Over time the gas giants migrate inward due to the irregular twisting motions of the gaseous disks in which they formed. As they move into their near-star orbits, hot Jupiters could be playing violent games of planetary billiards that produce Earthlike planets, he says.
Big Bullies
In general, massive gas giants have a reputation for slinging things around in space. Our Jupiter (Hubble image) is capable of hurling asteroids out of the solar system or into the sun and other planets by the sheer force of its gravity. "These gas giants cause quite a ruckus," Raymond said. Ten years ago, when scientists detected the first hot Jupiter, they assumed that as the giant exoplanets plowed through debris during their inward migrations, any surrounding material would be similarly ejected. He and his colleagues now think that such planets possibly only shake up debris in the habitable zone—the region at the right distance from a star where liquid water, necessary to life as we know it, could exist. This disrupted debris could coalesce into Earthlike planets. At the same time, small icy bodies from farther out in the star system also could have spiraled inward, delivering water to the fledgling planets. "We now think there is a new class of ocean-covered—and possibly habitable—planets in solar systems unlike our own," Raymond said. The simulations also showed that rocky planets known as hot Earths may often form when hot Jupiters push material forward during their inward treks. But hot Earths, which can be up to five times bigger than our Earth, orbit closer to their stars and are not likely to support life. Even if water does contribute to their formation, most hot Earths probably end up dry, study co-author Raymond says. "We don't think that they're really good places to harbor life, if you need liquid water on the surface [to support life]." Raymond and colleagues at Pennsylvania State University in University Park present their research in tomorrow's issue of the journal Science.
Telltale Wobble
For now, inhospitable gas giants appear to make up the majority of known planets outside our solar system. Astronomers have detected about 200 exoplanets, and 40 percent of them are hot Jupiters with orbits tighter than Mercury's. But the sample is biased, says study co-author Avi Mandell, an astrophysicist at Penn State and a researcher with the NASA Goddard Space Flight Center in Greenbelt, Maryland. That's because astronomers can't actually see the distant planets. They're mostly relying on the so-called Doppler wobble, the gravitational tug of the unseen planets on their host stars. The wobble decreases—and becomes harder to see—when it's caused by small planets that orbit farther away. As space scientists build ever bigger and more powerful telescopes, Mandell thinks higher percentages of small and distant planets will be found. The new findings will help narrow the search for life-supporting planets, the researchers write—just in time for NASA's upcoming Terrestrial Planet Finder mission and the European Space Agency's Darwin mission, which are dedicated to that effort. But other researchers are more cautious. Nick Woolf, an astronomer at the University of Arizona in Tucson, points out that the only certain planetary system we've actually seen is our own. "Our understanding of the processes that occur in the formation of a planetary system," he said, "is rudimentary."
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Topic: Astrography, Subject: Rogue Planets
Outcast Planets Could Support Life
by Jon Cartwright on 11 February 2011, 12:10 PM
Source:
Science Now
If aliens exist, where are they? Many astronomers look to the nearest stars, in the hope that they harbor a warm, wet planet like Earth. But now a pair of researchers believe extraterrestrial life could exist on a rogue planet that has been ejected from its birthplace.
Astronomers have never spotted a rogue planet with certainty, but computer simulations suggest that our galaxy could be teeming with them. Slingshotted out of their planetary system by the gravity of a bigger planet, these lone worlds zoom far from their parent suns, slowly freezing in the cold of outer space. Any water fit for life would freeze, too. Yet in a paper submitted to The Astrophysical Journal Letters, planetary scientists Dorian Abbot and Eric Switzer of the University of Chicago in Illinois suggest that a rogue planet could support a hidden ocean under its blanket of ice, kept warm by geothermal activity.
They call such a world a Steppenwolf planet after a novel by the German-Swiss author Hermann Hesse, because "any life ... would exist like a lone wolf wandering the galactic steppe." If Steppenwolf planets do exist, there's a chance that some of them could be lurking in space between Earth and nearby stars. If so, they might be a more realistic human destination for the search of alien life than another planetary system, which would be at least several light-years away. There is even a chance—albeit very small—that a Steppenwolf planet crashing into our solar system billions of years ago was the origin of life on Earth.
Abbot and Switzer came to their conclusion by simulating an isolated planet between 1/10th and 10 times the size of Earth. By comparing the rate at which heat would be lost through an ice shell with the rate at which heat would be produced by geothermal activity, they calculated that a planet with Earth's composition of rock and water but three times as big would generate enough heat to maintain a hidden ocean. If the planet had much more water than Earth, say Abbot and Switzer, it would need to be only about a third as big as our planet. "Several kilometers of water ice make an excellent blanket that could be sufficient to support liquid water at its base," says Switzer.
The Chicago researchers are not the first to consider the possibility of liquid water on rogue planets. In 1999, planetary scientist David Stevenson of the California Institute of Technology in Pasadena, calculated that liquid water could exist if a planet had a dense atmosphere of hydrogen—so dense that a greenhouse effect would trap warmth on the surface without the need for ice. But Abbot thinks the new result is more surprising because they are considering a more generic planet, without an extraordinary atmosphere.
"This is certainly an interesting study regarding the extent of the possible locations where life could arise, or be sustained, in the universe," says David Ehrenreich, a planetary scientist at the Joseph Fourier University in Grenoble, France. "However, it will certainly be very difficult to actually detect life on such a world, since it would be buried under an ice shell."
Switzer admits detection would be difficult. An astronomer would need to spot a Steppenwolf planet by looking for its infrared emission to see if it is as warm as he and Abbot predict. But at present, even the best observatories could detect rogue planets only within about 100 billion miles of Earth—not a huge distance in astronomical terms—and Switzer says the probability of a Steppenwolf planet existing in this range is just one in a billion.
Still, as planetary scientist Gaetano Di Achille of the University of Colorado, Boulder, points out, that might mean that the first occupied planet humans set foot on is not in another planetary system, but in the lonely depths of outer space. "If the hypothesis of oceans on rogue planets is correct, we will certainly have to expand the inventory of places with a high potential for life," he says.
Gaming Clack
The obvious advantages to rogue planets are too numerous to list. Their location and navigation coordinates do not appear with any reliable consistency on star charts. A moving stellar mass is harder to trace, locate, and travel to do to projected course. This can be solved, of course with warning beacons, orbital or planetary in manufacture.
As moving celestial bodies, they are at the mercy of gravitational pulls from other forms of galactic mass. Be it colossal gas giants, several gas giants, a star with a greater physical mass could easily "snag" a rogue plant and absorb it into it orbital rings. This planetary addition could play havoc with the original orbital configuration. A second theory explains it could "snag and sling" it back out of its adopted solar system on a new trajectory. The rogue planet could become a wayward orphan again.
Hyperspace travel becomes an obvious hazard as an exiting star ship could bounce off its atmosphere and burn in descent, or worse as a rogue planet passes dangerously close to a stellar anomaly, a quantum singularity of minute size, a pulsar, an asteroid field. An unexpected crew could find themselves in a dangerous predicament with little warning.
Rogue Planets can serve an excellent base of operations. Hoth, from the Empire Strikes Back, served as a Central Command Center, processing data and information do to its remote location and isolation. A Pirate's Haven would make an excellent locale for distributing services and goods like spice, weapons, slaves, whatnot. Rogue Planets with their limited eco-systems could serve as secure munition dumps, Research and Development faculties, or covert planetary shipyards.
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Topic: Astrography, Subject: Tilted Planet
Uranus Got Knocked Over by One-Two Punch
New models explain planet's tilted orbit, moon mystery.
Andrew Fazekas
for
National Geographic News
Published October 10, 2011
The planet Uranus got knocked on its side not by a single, massive blow but by two powerful impacts, new computer simulations hint.
The model helps explain a long-standing mystery: Why do Uranus's moons also lie in unexpected positions?
Unlike the other seven planets, Uranus's rotation axis has a bizarre 98-degree tilt relative to the solar system's orbital plane. In other words, the planet seems to roll around on its side as it orbits the sun.
Even odder, the rings and moons of Uranus circle the planet's tilted equator.
The widely accepted theory for how Uranus got knocked over is that a rogue Earth-size planet slammed into the ice giant billions of years ago. That lost world was mostly likely destroyed on impact.
But previous computer simulations showed that a single extreme impact wouldn't have affected Uranus's retinue of more than 25 moons, and the moons should now be circling the planet's poles instead of its equator.
Single Blow Would Have Meant "Backward" Moons
To explore this conundrum, a team led by Alessandro Morbidelli, of the Observatoire de la Cote d’Azur in France, ran several simulations of possible Uranus impacts.
The results showed that Uranus was most likely struck when its moons and rings were still forming from a disk of debris around the ice giant's equator.
When Uranus was hit, this disk was disrupted but then reformed around the planet's tilted equator, eventually giving rise to the moons in the positions we see today.
In the new simulations, however, a single impact led to moons that orbit "backward"—in the opposite direction of the planet's spin.
Instead, the most likely scenario involves a closely spaced double impact, Morbidelli's team found.
"Our computer simulations show that two sequential impacts occurred very early in the planet's history, when it was still surrounded by a protosatellite disk, and should have occurred relatively close in time," Morbidelli said.
"So far, this is the only model that explains the equatorial orbits of Uranus's satellites."
Big Impacts Once the Norm Among Giants?
The results suggest that giant impacts may have been more common than previously thought in the early days of the solar system, when today's planets were still sweeping up smaller objects from the large debris disk surrounding our young sun.
In fact, big collisions could have been important factors in the formation of planets such as Saturn and Neptune, which both display 30-degree tilts in their axes.
"In general, scientists have thought that these planets formed by accreting only small planetesimals, and the Uranus tilting event was an exceptional event," Morbidelli said.
"But now we show that Uranus has to have been tilted at least twice, so these giant impacts were not exceptional events—they were the norm."
Topic: Astrography, Subject: The Triplets
Bizarre solar system crams three giant planets into fraction of Mercury’s orbit
BY ALASDAIR WILKINS
OCT 4, 2011 4:00 PM
from
Io9.com
The Kepler-18 system is one of the galaxy's busiest places, with two Neptune-sized planets and a super-Earth orbiting around a single star. We know this, thanks to a bold new exoplanet-hunting technique that could help us find more Earth-like planets.
The planets are designated Kepler-18 b, c, and d. Planet b is the closest, completing an orbit every 3.5 days. The planet is a rocky super-Earth, weighing in at about seven times Earth's mass and twice our planet's size. Planets c and d are gas planets roughly the size of Neptune or Uranus. Planet c orbits every 7.6 days, it's 17 times more massive than Earth, and about 5.5 times our size. Finally, planet d is about 16 times more massive than Earth, 7 times our volume, and orbits every 14.9 days.
That's a whole lot of planets to stick into such a tiny amount of space, and it's not as though Kepler-18 is anything unusual as far as stars go. It's broadly similar to our Sun, about 97% the mass and about 1.1 times our star's size. What's more, the planets are trapped in a bizarre pattern. Planets c and d appear to be in a 2:1 resonance pattern, where planet c revolves around Kepler-18 twice for every one orbit planet d completes.
But the orbits don't quite line up to an exact 2:1 resonance, and that's because they're so close together that they're constantly pushing and pulling each other out of their natural orbits. University of Texas astronomer Bill Cochran explains:
"[They] are not staying exactly on that orbital period. One is slightly early when the other one is slightly late, [then] both are on time at the same time, and then vice-versa. It means they're interacting with each other. When they are close to each other...they exchange energy, pull and tug on each other."
Kepler-18 also represents the first chance for astronomers to use a new exoplanet-hunting methodology. Generally speaking, planets are found by the transit method, which detects planet by looking for regular dips in the brightness of a star that could only be caused by an orbiting planet passing in front of it. While false positives are possible with this approach, the resonance patterns between planets c and d quickly proved their existence — only two planets that were really in the same solar system could produce such a pattern.
But planet b is a trickier case, and it gave Cochran and his team a chance to try out the new approach of "validation", rather than "verification." What this means is they didn't set out to directly prove the existence of the planet; instead, they figured out the odds that this wasn't a planet. To do that, they used the Palomar 5-meter Hale Telescope to search the area around Kepler-18 for any objects that could mimic the signature of a transiting planet.
Cochran explains that, while it's still conceivable Kepler-18 b is really a perfectly positioned background star or galaxy, the probability is next to nothing:
"We successively went through every possible type of object that could be there. There are limits on the sort of objects that can be there at different distances from the star. There's a small possibility that [planet b] is due to a background object, but we're very confident that it's probably a planet."
According to their calculations, it's about 700 times more likely that Kepler-18 b is a planet than anything else. Cochran hopes that validation will catch on as a method of exoplanet validation, because it will allow astronomers to pinpoint potential planets that fall outside the relatively narrow range of easy verification. He explains:
"We're trying to prepare the astronomical community and the public for the concept of validation. The goal of Kepler is to find an Earth-sized planet in the habitable zone [where life could arise], with a one-year orbit. Proving that such an object really is a planet is very difficult [with current technology]. When we find what looks to be a habitable Earth, we'll have to use a validation process, rather than a confirmation process. We're going to have to make statistical arguments."
Those arguments would have seemed a lot shakier a few years ago, when only a relatively small number of exoplanets were known. But now that the Kepler mission has identified over a thousand exoplanet candidates, and current estimates suggest there are millions and millions of planets in our galaxy - if not billions - validation seems like a much more reasonable option than it once might have.
Topic: Heliology, Subject: The Diamond Pulsar
A destroyed star becomes a planet made of diamonds
BY ESTHER INGLIS-ARKELL
AUG 25, 2011
from
Io9.com
An international research team has found an exoplanet made entirely of diamonds. Although this may seem glamorous, researchers think it is only the desolate remains of a star, robbed of its mass by its companion.
Some time ago, a radio telescope picked up the repeated signal of a pulsar. A pulsar is a rapidly-spinning star with a rotation that emits radio waves in strong pulses outwards. This pulsar lay in the plane of the Milky Way, not particularly distinguishing itself from any other pulsar out there. That is, until the astronomers analyzed the spin of the pulsar and found that it was modulated in a certain way. It was almost as if the star was being tugged one way or another via gravity. The only thing that could be making that particular spin was an orbiting planet.
This planet was orbiting fast and close. It was circling the pulsar once every two hours and ten minutes, at a distance just about the radius of Earth's sun. It was about five times the size of earth, a relatively small planet, but it had the mass of Jupiter. This planet should not have gathered so much mass and packed it so tightly when it was so close to a high-gravity star.
Scientists think that it didn't. Actually, the planet is the remains of a star. The pulsar and the newly-discovered planet were once a binary system. As they burnt through their fuel and came closer to one another, one star starting siphoning off the matter of the other. When it was done, it left only a cold, fusion-less planet.
But a pretty one. Judging from the size and mass of the star, scientists think that a very large part of it will be crystalline carbon - the same stuff that diamonds are made of. The theft of most of its fuel left this celestial body a glittering jewel.
Topic: Heliology, Subject: "Nightmare" Sun
"Nightmare" Star Flares Dim Odds for Alien Life?
Richard A. Lovett in Seattle, Washington
for
National Geographic News
Published January 24, 2011
In the search for life on Earthlike planets, scientists have been particularly excited about finding worlds in the so-called Goldilocks zone, the region around a star that's just right for liquid water. But new research suggests that—Goldilocks or not—many of the known planets outside our solar system are orbiting stars that may be too hazardous for life. According to a new study, Jupiter-size planets in close orbits around their stars can make their middle-age stellar parents unexpectedly regain the violence of youth. Such stars produce gigantic flares, which could shower otherwise habitable planets with dangerous radiation, searing blasts of heat, and ozone-destroying ultraviolet light. In a related study, astronomers also found that old, dim stars in tight-knit pairs appear to be experiencing a similar effect, producing mega-flares that quickly and suddenly brighten the stars by up to 10 percent. "Imagine our sun brightening by 10 percent," said Geoffrey Marcy, an astronomer at the University of California, Berkeley, who was not part of either study. "Such powerful flares [would] bode ill for life close to that star."
"Nightmare" Flares Could Wreck Ozone Layer
Young stars are often spinning very rapidly shortly after birth, creating strong magnetic fields. Various forces on the star's surface cause magnetic field lines to get tied into knots, which produce flares and other types of radiation bursts. An extreme example is the red dwarf star YZ CMi, a young star that's probably only a few hundred million years old. By contrast, our sun is considered middle aged, at 4.5 billion years old.
YZ CMi rotates on its axis once every 2.8 days, nearly ten times faster than the sun. This spin is fast enough to produce stunningly violent flares, said Adam Kowalski, a graduate student at the University of Washington. In 2009, Kowalski watched as a particularly large flare jacked up YZ CMi's ultraviolet emissions by a factor of more than 200—enough to totally wreck the ozone layer of any rocky world orbiting within the star's habitable zone. "I have nightmares about this flare," Kowalski said earlier this month during a meeting of the American Astronomical Society in Seattle, Washington.
Big, Hot Planets Are "Fountains of Youth"
As a star ages, its spin will slow, which should tame its violence. Our sun, for example, still goes through cycles of activity and produces flares—some of which can be powerful enough to disable satellites or knock out power grids—but nothing on the scale of YZ CMi. Recently, however, Villanova University astronomer Edward Guinan saw giant x-ray flares, large star spots, and powerful coronal mass ejections coming from a star that should be about the same age as the sun. HD 189733 is an orange dwarf star that's 80 percent the size of the sun but that spins twice as fast: once every 12 days. Based on its activity levels, the star would seem to be about 600 million years old. The hyperactive star has a distant, more sedate companion star, which astronomers estimate is at least 4.5 billion years old. That's puzzling, since the two stars almost certainly formed at the same time and should be the same age, Guinan said. What's keeping HD 189733 dangerously young, Guinan said, is a Jupiter-size planet that's slowly spiraling into its host. This "hot Jupiter" is so close to the star that it orbits once every 2.2 days. In the process, the planet's magnetic field is pushing against the star's, Guinan said, transferring angular momentum and making the star spin faster. Astronomers don't know if the HD 189733 system hosts any rocky, Earthlike worlds. But thanks to the hot Jupiter, the star's youthful behavior would likely spell doom for life on any other potential planets. The finding could be a blow to the wider hunt for habitable worlds: Many of the more then 500 extrasolar planets found so far are hot Jupiters, and computer models suggest that more than a third of the star systems containing these giants may also harbor Earthlike planets. "In our study of other hot Jupiter systems," Guinan said, "it looks like many of the host stars rotate fast and appear young."
Hopes Dim For Life Under Twin Suns
In addition to hot Jupiters, some older stars may be tapping into a "fountain of youth" in the form of close stellar siblings. At the AAS meeting, the University of Washington's Kowalski presented Hubble Space Telescope data on 200,000 dim stars about twice the age of the sun. These types of stars, among the most plentiful in the galaxy, should have been among the most tranquil. But in the course of a week, Kowalski counted a hundred stars that emitted superhigh-energy flares, each strong enough to increase the star's brightness by up to 10 percent. "This is much larger than the largest solar flare we have observed" on our sun, he said. Astronomers don't yet know whether these stars host planets of any size. What scientists do know is that all these stars have stellar companions in extremely close orbits. The stars are so close they are tidally locked, which means that one side of a star always faces its companion, just as one side of the moon always faces Earth. Some of the tightest pairs orbit each other—and therefore spin on their axes—once every three days, Kowalski said, "which is really fast." And the intense activity coming from such rapidly spinning stars would put a serious damper on the chances of life existing on nearby planets. According to UC Berkeley's Marcy, "it's interesting that the most numerous stars in our galaxies pose these risks."
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