NASA's Kepler Announces 11 New Planetary Systems Hosting 26 Planets

This artist's concept shows an overhead view of the orbital position of the planets in systems with multiple transiting planets discovered by NASA's Kepler mission. All the colored planets have been verified. More vivid colors indicate planets that have been confirmed by their gravitational interactions with each other or the star. Several of these systems contain additional planet candidates (shown in grey) that have not yet been verified. (Credit: NASA Ames/UC Santa Cruz)

NASA's Kepler mission has discovered 11 new planetary systems hosting 26 confirmed planets. These discoveries nearly double the number of verified Kepler planets and triple the number of stars known to have more than one planet that transits, or passes in front of, the star. Such systems will help astronomers better understand how planets form.

The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen are between Earth and Neptune in size. Further observations will be required to determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune. The planets orbit their host star once every six to 143 days. All are closer to their host star than Venus is to our sun.

"Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits."

Kepler identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars to detect when a planet passes in front of the star. That passage casts a small shadow toward Earth and the Kepler spacecraft.

"Confirming that the small decrease in the star's brightness is due to a planet requires additional observations and time-consuming analysis," said Eric Ford, associate professor of astronomy at the University of Florida and lead author of the paper confirming Kepler-23 and Kepler-24. "We verified these planets using new techniques that dramatically accelerated their discovery."

Each of the newly confirmed planetary systems contains two to five closely spaced transiting planets. In tightly packed planetary systems, the gravitational pull of the planets on each other causes some planets to accelerate and some to decelerate along their orbits. The acceleration causes the orbital period of each planet to change. Kepler detects this effect by measuring the changes, or so-called Transit Timing Variations.

Planetary systems with Transit Timing Variations can be verified without requiring extensive ground-based observations, accelerating confirmation of planet candidates. This detection technique also increases Kepler's ability to confirm planetary systems around fainter and more distant stars.

"By precisely timing when each planet transits its star, Kepler detected the gravitational tug of the planets on each other, clinching the case for 10 of the newly announced planetary systems," said Dan Fabrycky, Hubble Fellow at the University of California, Santa Cruz, and lead author for a paper confirming Kepler-29, 30, 31 and 32.

Five of the systems (Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33) contain a pair of planets where the inner planet orbits the star twice during each orbit of the outer planet. Four of the systems (Kepler-23, Kepler-24, Kepler-28 and Kepler-32) contain a pairing where the outer planet circles the star twice for every three times the inner planet orbits its star.

"These configurations help to amplify the gravitational interactions between the planets, similar to how my sons kick their legs on a swing at the right time to go higher," said Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Ill., and lead author of a paper confirming Kepler-25, 26, 27 and 28.

Kepler-33, a star that is older and more massive than our sun, had the most planets. The system hosts five planets, ranging in size from 1.5 to 5 times that of Earth. All of the planets are located closer to their star than any planet is to our sun.

The properties of a star provide clues for planet detection. The decrease in the star's brightness and duration of a planet transit combined with the properties of its host star present a recognizable signature. When astronomers detect planet candidates that exhibit similar signatures around the same star, the likelihood of any of these planet candidates being a false positive is very low.

"The approach used to verify the Kepler-33 planets shows the overall reliability is quite high," said Jack Lissauer, planetary scientist at NASA Ames Research Center at Moffett Field, Calif., and lead author of the paper on Kepler-33. "This is a validation by multiplicity."

These discoveries are published in four different papers in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.

Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., managed the Kepler mission's development.

Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission and to view the digital press kit, visit http://www.nasa.gov/kepler . More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov 

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Planets smashed into dust near supermassive black holes

ScienceDaily (Oct. 28, 2011) — Fat doughnut-shaped dust shrouds that obscure about half of supermassive black holes could be the result of high speed crashes between planets and asteroids, according to a new theory from an international team of astronomers.

The scientists, led by Dr. Sergei Nayakshin of the University of Leicester, are publishing their results in the journal Monthly Notices of the Royal Astronomical Society.

Supermassive black holes reside in the central parts of most galaxies. Observations indicate that about 50% of them are hidden from view by mysterious clouds of dust, the origin of which is not completely understood. The new theory is inspired by our own Solar System, where the so-called zodiacal dust is known to originate from collisions between solid bodies such as asteroids and comets. The scientists propose that the central regions of galaxies contain not only black holes and stars but also planets and asteroids.

Collisions between these rocky objects would occur at colossal speeds as large as 1000 km per second, continuously shattering and fragmenting the objects, until eventually they end up as microscopic dust. Dr. Nayakshin points out that this harsh environment -- radiation and frequent collisions -- would make the planets orbiting supermassive black holes sterile, even before they are destroyed. "Too bad for life on these planets," he says, "but on the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy."

He also believes that understanding the origin of the dust near black holes is important in our models of how these monsters grow and how exactly they affect their host galaxies. "We suspect that the supermassive black hole in our own Galaxy, the Milky Way, expelled most of the gas that would otherwise turn into more stars and planets," he continues, "Understanding the origin of the dust in the inner regions of galaxies would take us one step closer to solving the mystery of the supermassive black holes."

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Sergei Nayakshin, Sergey Sazonov, Rashid Sunyaev. Are SMBHs shrouded by 'super-Oort' clouds of comets and asteroids? Monthly Notices of the Royal Astronomical Society, 2011; (submitted) [link]

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Planets smashed into dust near supermassive black holes

ScienceDaily (Oct. 28, 2011) — Fat doughnut-shaped dust shrouds that obscure about half of supermassive black holes could be the result of high speed crashes between planets and asteroids, according to a new theory from an international team of astronomers.

The scientists, led by Dr. Sergei Nayakshin of the University of Leicester, are publishing their results in the journal Monthly Notices of the Royal Astronomical Society.

Supermassive black holes reside in the central parts of most galaxies. Observations indicate that about 50% of them are hidden from view by mysterious clouds of dust, the origin of which is not completely understood. The new theory is inspired by our own Solar System, where the so-called zodiacal dust is known to originate from collisions between solid bodies such as asteroids and comets. The scientists propose that the central regions of galaxies contain not only black holes and stars but also planets and asteroids.

Collisions between these rocky objects would occur at colossal speeds as large as 1000 km per second, continuously shattering and fragmenting the objects, until eventually they end up as microscopic dust. Dr. Nayakshin points out that this harsh environment -- radiation and frequent collisions -- would make the planets orbiting supermassive black holes sterile, even before they are destroyed. "Too bad for life on these planets," he says, "but on the other hand the dust created in this way blocks much of the harmful radiation from reaching the rest of the host galaxy. This in turn may make it easier for life to prosper elsewhere in the rest of the central region of the galaxy."

He also believes that understanding the origin of the dust near black holes is important in our models of how these monsters grow and how exactly they affect their host galaxies. "We suspect that the supermassive black hole in our own Galaxy, the Milky Way, expelled most of the gas that would otherwise turn into more stars and planets," he continues, "Understanding the origin of the dust in the inner regions of galaxies would take us one step closer to solving the mystery of the supermassive black holes."

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Journal Reference:

Sergei Nayakshin, Sergey Sazonov, Rashid Sunyaev. Are SMBHs shrouded by 'super-Oort' clouds of comets and asteroids? Monthly Notices of the Royal Astronomical Society, 2011; (submitted) [link]

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Spiral arms hint at presence of planets: High resolution image of young star with circumstellar disks verifies predictions

ScienceDaily (Oct. 19, 2011) — A new image of the disk of gas and dust around a sun-like star has spiral-arm-like structures. These features may provide clues to the presence of embedded but as-yet-unseen planets.

"Detailed computer simulations have shown us that the gravitational pull of a planet inside a circumstellar disk can perturb gas and dust, creating spiral arms. Now, for the first time, we're seeing these features," said Carol Grady, a National Science Foundation (NSF)-supported astronomer with Eureka Scientific, Inc.

The newly imaged disk surrounds SAO 206462, a star located about 456 light-years away in the constellation Lupus. Astronomers estimate that the system is only about 9 million years old. The gas-rich disk spans some 14 billion miles, which is more than twice the size of Pluto's orbit in our own solar system.

"The surprise," said Grady, "was that we caught a glimpse of this stage of planet formation. This is a relatively short-lived phase."

A near-infrared image from the National Astronomical Observatory of Japan shows a pair of spiral features arcing along the outer disk. Theoretical models show that a single embedded planet may produce a spiral arm on each side of a disk. The structures around SAO 206462 do not form a matched pair, suggesting the presence of two unseen worlds, one for each arm. However, the research team cautions that processes unrelated to planets may also give rise to these structures.

"What we're finding is that once these systems reach ages of a few million years, their disks begin to show a wealth of structure--rings, divots, gaps and now spiral features," said John Wisniewski, a collaborator at the University of Washington in Seattle. "Many of these structures could be caused by planets within the disks."

Grady's research is part of the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS), a five-year-long near-infrared study of young stars and their surrounding dust disks using the Subaru Telescope atop Mauna Kea in Hawaii. The international consortium of researchers now includes more than 100 scientists at 25 institutions.

"These arm-like structures have been predicted by models, but have never before been seen," said Maria Womack, program director for the division of Astronomical Sciences at NSF. "It is the first observation of spiral arms in a circumstellar disk, and an important test for models of planetary formation."

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Astronomers find elusive planets in decade-old Hubble data

ScienceDaily (Oct. 6, 2011) — In a painstaking re-analysis of Hubble Space Telescope images from 1998, astronomers have found visual evidence for two extrasolar planets that went undetected back then.

Finding these hidden gems in the Hubble archive gives astronomers an invaluable time machine for comparing much earlier planet orbital motion data to more recent observations. It also demonstrates a novel approach for planet hunting in archival Hubble data.

Four giant planets are known to orbit the young, massive star HR 8799, which is130 light-years away. In 2007 and 2008 the first three planets were discovered in near-infrared ground-based images taken with the W.M. Keck Observatory and the Gemini North telescope by Christian Marois of the National Research Council in Canada and his team. Marois and his colleagues then uncovered a fourth innermost planet in 2010. This is the only multiple exoplanetary system for which astronomers have obtained direct snapshots.

In 2009 David Lafreniere of the University of Montreal recovered hidden exoplanet data in Hubble images of HR 8799 taken in 1998 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). He identified the position of the outermost planet known to orbit the star. This first demonstrated the power of a new data-processing technique for retrieving faint planets buried in the glow of the central star.

A new analysis of the same archival NICMOS data by Remi Soummer of the Space Telescope Science Institute in Baltimore has recovered all three of the outer planets. The fourth, innermost planet is 1.5 billion miles from the star and cannot be seen because it is on the edge of the NICMOS coronagraphic spot that blocks the light from the central star.

By finding the planets in multiple images spaced over years of time, the orbits of the planets can be tracked. Knowing the orbits is critical to understanding the behavior of multiple-planet systems because massive planets can perturb each other's orbits. "From the Hubble images we can determine the shape of their orbits, which brings insight into the system stability, planet masses and eccentricities, and also the inclination of the system," says Soummer.

These results are to be published in the Astrophysical Journal.

The three outer gas-giant planets have approximately 100-, 200-, and 400-year orbits. This means that astronomers need to wait a very long time to see how the planets move along their paths. The added time span from the Hubble data helps enormously. "The archive got us 10 years of science right now," he says. "Without this data we would have had to wait another decade. It's 10 years of science for free."

Nevertheless, the slowest-moving, outermost planet has barely changed position in 10 years. "But if we go to the next inner planet we see a little bit of an orbit, and the third inner planet we actually see a lot of motion," says Soummer.

The planets weren't found in 1998 when the Hubble observations were first taken because the methods used to detect them were not available at that time. When astronomers subtracted the light from the central star to look for the residual glow of planets, the residual light scatter was still overwhelming the faint planets.

Lafreniere developed a way to improve this type of analysis by using a library of reference stars to more precisely remove the "fingerprint" glow of the central star. Soummer's team took Lafreniere's method a step further and used 466 images of reference stars taken from a library containing over 10 years of NICMOS observations assembled by Glenn Schneider of the University of Arizona.

Soummer's team further increased contrast and minimized residual starlight. They completely removed the diffraction spikes, which are artifacts common to telescope imaging systems. This allowed them to see two of the faint inner planets in the Hubble data. The planets recovered in the NICMOS data are about 1/100,000th the brightness of the parent star when viewed in near-infrared light.

Soummer next plans to analyze approximately 400 other stars in the NICMOS archive with the same technique, improving image quality by a factor of 10 over the imaging methods used when the data were obtained.

Soummer's work demonstrates the power of the Hubble Space Telescope data archive, which harbors images and spectral information from over twenty years of Hubble observations. Astronomers tap into this library to complement new observations with a wealth of invaluable data already gathered, yielding much more discovery potential than new observations alone.

From the NICMOS archive data Soummer's team will assemble a list of planetary candidates to be confirmed by ground-based telescopes. If new planets are discovered they will once again have several years' worth of orbital motion to measure.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Goddard Space Flight Center.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Astronomers find elusive planets in decade-old Hubble data

ScienceDaily (Oct. 6, 2011) — In a painstaking re-analysis of Hubble Space Telescope images from 1998, astronomers have found visual evidence for two extrasolar planets that went undetected back then.

Finding these hidden gems in the Hubble archive gives astronomers an invaluable time machine for comparing much earlier planet orbital motion data to more recent observations. It also demonstrates a novel approach for planet hunting in archival Hubble data.

Four giant planets are known to orbit the young, massive star HR 8799, which is130 light-years away. In 2007 and 2008 the first three planets were discovered in near-infrared ground-based images taken with the W.M. Keck Observatory and the Gemini North telescope by Christian Marois of the National Research Council in Canada and his team. Marois and his colleagues then uncovered a fourth innermost planet in 2010. This is the only multiple exoplanetary system for which astronomers have obtained direct snapshots.

In 2009 David Lafreniere of the University of Montreal recovered hidden exoplanet data in Hubble images of HR 8799 taken in 1998 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). He identified the position of the outermost planet known to orbit the star. This first demonstrated the power of a new data-processing technique for retrieving faint planets buried in the glow of the central star.

A new analysis of the same archival NICMOS data by Remi Soummer of the Space Telescope Science Institute in Baltimore has recovered all three of the outer planets. The fourth, innermost planet is 1.5 billion miles from the star and cannot be seen because it is on the edge of the NICMOS coronagraphic spot that blocks the light from the central star.

By finding the planets in multiple images spaced over years of time, the orbits of the planets can be tracked. Knowing the orbits is critical to understanding the behavior of multiple-planet systems because massive planets can perturb each other's orbits. "From the Hubble images we can determine the shape of their orbits, which brings insight into the system stability, planet masses and eccentricities, and also the inclination of the system," says Soummer.

These results are to be published in the Astrophysical Journal.

The three outer gas-giant planets have approximately 100-, 200-, and 400-year orbits. This means that astronomers need to wait a very long time to see how the planets move along their paths. The added time span from the Hubble data helps enormously. "The archive got us 10 years of science right now," he says. "Without this data we would have had to wait another decade. It's 10 years of science for free."

Nevertheless, the slowest-moving, outermost planet has barely changed position in 10 years. "But if we go to the next inner planet we see a little bit of an orbit, and the third inner planet we actually see a lot of motion," says Soummer.

The planets weren't found in 1998 when the Hubble observations were first taken because the methods used to detect them were not available at that time. When astronomers subtracted the light from the central star to look for the residual glow of planets, the residual light scatter was still overwhelming the faint planets.

Lafreniere developed a way to improve this type of analysis by using a library of reference stars to more precisely remove the "fingerprint" glow of the central star. Soummer's team took Lafreniere's method a step further and used 466 images of reference stars taken from a library containing over 10 years of NICMOS observations assembled by Glenn Schneider of the University of Arizona.

Soummer's team further increased contrast and minimized residual starlight. They completely removed the diffraction spikes, which are artifacts common to telescope imaging systems. This allowed them to see two of the faint inner planets in the Hubble data. The planets recovered in the NICMOS data are about 1/100,000th the brightness of the parent star when viewed in near-infrared light.

Soummer next plans to analyze approximately 400 other stars in the NICMOS archive with the same technique, improving image quality by a factor of 10 over the imaging methods used when the data were obtained.

Soummer's work demonstrates the power of the Hubble Space Telescope data archive, which harbors images and spectral information from over twenty years of Hubble observations. Astronomers tap into this library to complement new observations with a wealth of invaluable data already gathered, yielding much more discovery potential than new observations alone.

From the NICMOS archive data Soummer's team will assemble a list of planetary candidates to be confirmed by ground-based telescopes. If new planets are discovered they will once again have several years' worth of orbital motion to measure.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

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Blackberry Service Finally Restored on All Planets

Interplanetary Outage via TechCrunch

RIM said Thursday morning its BlackBerry service had been restored to all terrestrial worlds after the worst outage ever. BlackBerry Messenger is still spotty on Vulcan, but service is back to normal in the other Federation planets.

The company said in an investor call that its infrastructure suffered a hardware error and the problem cascaded, CNN reported today.

[via TechCrunch]

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From the comfort of home, web users may have found new planets

ScienceDaily (Sep. 25, 2011) — Since the online citizen science project Planet Hunters launched last December, 40,000 web users from around the world have been helping professional astronomers analyze the light from 150,000 stars in the hopes of discovering Earth-like planets orbiting around them.

Users analyze real scientific data collected by NASA's Kepler mission, which has been searching for planets beyond our own solar system -- called exoplanets -- since its launch in March 2009.

Now astronomers at Yale University have announced the discovery of the first two potential exoplanets discovered by Planet Hunters users in a new study to be published in the Monthly Notices of the Royal Astronomical Society.

"This is the first time that the public has used data from a NASA space mission to detect possible planets orbiting other stars," said Yale astronomer and exoplanet expert Debra Fischer, who helped launch the Planet Hunters project.

The candidate planets orbit their host stars with periods ranging from 10 to 50 days -- much shorter than the 365 days it takes Earth to orbit the Sun -- and have radii that range in size from two-and-a-half to eight times Earth's radius. Despite those differences, one of the two candidates could be a rocky planet similar to the size of Earth (as opposed to a giant gas planet like Jupiter), although they aren't in the so-called "habitable zone" where liquid water, and therefore life as we know it, could exist.

Next, the Planet Hunters team -- a collaboration between astronomers at Yale, the University of Oxford and the Adler Planetarium in Chicago -- used the Keck Observatory in Hawaii to analyze the host stars. "I think there's a 95 percent chance or greater that these are bona fide planets," Fischer said.

The Kepler team has already announced the discovery of 1200 exoplanet candidates and will follow up on the highest potential ones with further analysis, but they had discarded the two found by Planet Hunters users for various technical reasons that led them to believe they weren't promising candidates.

"These three candidates might have gone undetected without Planet Hunters and its citizen scientists," said Meg Schwamb, a Yale researcher and Planet Hunters co-founder. "Obviously Planet Hunters doesn't replace the analysis being done by the Kepler team. But it has proven itself to be a valuable tool in the search for other worlds."

Users found the two candidates in the first month of Planet Hunters operations using data the Kepler mission made publicly available. The Planet Hunters team sent the top 10 candidates found by the citizen scientists to the Kepler team, who analyzed the data and determined that two of the 10 met their criteria for being classified as planet candidates. The two candidates were flagged as potential planets by several dozen different Planet Hunters users, as the same data are analyzed by more than one user.

"Scientists on the Kepler team obtained the data, but the public helped finance the project with their tax dollars," Fischer said. "It's only right that this data has been pushed back into the public domain, not just as scientifically digested results but in a form where the public can actively participate in the hunt. The space program is a national treasure -- a monument to America's curiosity about the Universe. It is such an exciting time to be alive and to see these incredible discoveries being made."

Planet Hunters users are now sifting through the next 90 days of Kepler data in the hopes of adding to the count. "This is what we found after just a preliminary glance through the first round of Kepler data," Fischer said. "There's no doubt that, with each new round of data, there will be more discoveries to come."

Learn more about Planet Hunters at: http://www.planethunters.org.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Yale University. The original article was written by Karen N. Peart.

Journal Reference:

Debra Fischer, Megan Schwamb, Kevin Schawinski, Chris Lintott, John Brewer, Matt Giguere, Stuart Lynn, Michael Parrish, Thibault Sartori, Robert Simpson, Arfon Smith, Julien Spronck, Natalie Batalha, Jason Rowe, Jon Jenkins, Steve Bryson, Andrej Prsa, Peter Tenenbaum, Justin Crepp, Tim Morton, Andrew Howard, Michele Beleu, Zachary Kaplan, Nick vanNispen, Charlie Sharzer, Justin DeFouw, Agnieszka Hajduk, Joe Neal, Adam Nemec, Nadine Schuepbach, Valerij Zimmermann. Planet Hunters: The First Two Planet Candidates Identified by the Public using the Kepler Public Archive Data. Monthly Notices of the Royal Astronomical Society, 2011; (submitted) [link]

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

From the comfort of home, web users may have found new planets

ScienceDaily (Sep. 25, 2011) — Since the online citizen science project Planet Hunters launched last December, 40,000 web users from around the world have been helping professional astronomers analyze the light from 150,000 stars in the hopes of discovering Earth-like planets orbiting around them.

Users analyze real scientific data collected by NASA's Kepler mission, which has been searching for planets beyond our own solar system -- called exoplanets -- since its launch in March 2009.

Now astronomers at Yale University have announced the discovery of the first two potential exoplanets discovered by Planet Hunters users in a new study to be published in the Monthly Notices of the Royal Astronomical Society.

"This is the first time that the public has used data from a NASA space mission to detect possible planets orbiting other stars," said Yale astronomer and exoplanet expert Debra Fischer, who helped launch the Planet Hunters project.

The candidate planets orbit their host stars with periods ranging from 10 to 50 days -- much shorter than the 365 days it takes Earth to orbit the Sun -- and have radii that range in size from two-and-a-half to eight times Earth's radius. Despite those differences, one of the two candidates could be a rocky planet similar to the size of Earth (as opposed to a giant gas planet like Jupiter), although they aren't in the so-called "habitable zone" where liquid water, and therefore life as we know it, could exist.

Next, the Planet Hunters team -- a collaboration between astronomers at Yale, the University of Oxford and the Adler Planetarium in Chicago -- used the Keck Observatory in Hawaii to analyze the host stars. "I think there's a 95 percent chance or greater that these are bona fide planets," Fischer said.

The Kepler team has already announced the discovery of 1200 exoplanet candidates and will follow up on the highest potential ones with further analysis, but they had discarded the two found by Planet Hunters users for various technical reasons that led them to believe they weren't promising candidates.

"These three candidates might have gone undetected without Planet Hunters and its citizen scientists," said Meg Schwamb, a Yale researcher and Planet Hunters co-founder. "Obviously Planet Hunters doesn't replace the analysis being done by the Kepler team. But it has proven itself to be a valuable tool in the search for other worlds."

Users found the two candidates in the first month of Planet Hunters operations using data the Kepler mission made publicly available. The Planet Hunters team sent the top 10 candidates found by the citizen scientists to the Kepler team, who analyzed the data and determined that two of the 10 met their criteria for being classified as planet candidates. The two candidates were flagged as potential planets by several dozen different Planet Hunters users, as the same data are analyzed by more than one user.

"Scientists on the Kepler team obtained the data, but the public helped finance the project with their tax dollars," Fischer said. "It's only right that this data has been pushed back into the public domain, not just as scientifically digested results but in a form where the public can actively participate in the hunt. The space program is a national treasure -- a monument to America's curiosity about the Universe. It is such an exciting time to be alive and to see these incredible discoveries being made."

Planet Hunters users are now sifting through the next 90 days of Kepler data in the hopes of adding to the count. "This is what we found after just a preliminary glance through the first round of Kepler data," Fischer said. "There's no doubt that, with each new round of data, there will be more discoveries to come."

Learn more about Planet Hunters at: http://www.planethunters.org.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Yale University. The original article was written by Karen N. Peart.

Journal Reference:

Debra Fischer, Megan Schwamb, Kevin Schawinski, Chris Lintott, John Brewer, Matt Giguere, Stuart Lynn, Michael Parrish, Thibault Sartori, Robert Simpson, Arfon Smith, Julien Spronck, Natalie Batalha, Jason Rowe, Jon Jenkins, Steve Bryson, Andrej Prsa, Peter Tenenbaum, Justin Crepp, Tim Morton, Andrew Howard, Michele Beleu, Zachary Kaplan, Nick vanNispen, Charlie Sharzer, Justin DeFouw, Agnieszka Hajduk, Joe Neal, Adam Nemec, Nadine Schuepbach, Valerij Zimmermann. Planet Hunters: The First Two Planet Candidates Identified by the Public using the Kepler Public Archive Data. Monthly Notices of the Royal Astronomical Society, 2011; (submitted) [link]

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Sun and planets constructed differently, analysis from NASA mission suggests

ScienceDaily (June 30, 2011) — The sun and the solar system's rocky inner planets, including Earth, may have formed differently than previously thought, according to UCLA scientists and colleagues analyzing samples returned by NASA's Genesis mission.

The data from Genesis, which collected material from the solar wind blowing from the sun, reveal differences between the sun and planets with regard to oxygen and nitrogen, two of the most abundant elements in our solar system, the researchers report in two studies in the June 24 issue of the journal Science. And although the differences are slight, the research could help determine how our solar system evolved.

"We want to understand how rocky planets form, particularly our rocky planet," said Genesis co-investigator and UCLA professor of Earth and space sciences Kevin McKeegan, who was the lead author of the Science study on oxygen. "To understand that, we need to understand how the isotope composition of the most abundant element in the Earth came to be what it is."

On Earth, the air contains three kinds, or isotopes, of oxygen atoms, which differ in the number of neutrons they contain. All three have eight protons, and almost all have eight neutrons (O-16), but a small proportion of isotopes contain nine neutrons (O-17) or 10 neutrons (O-18). Although isotopes of an element behave similarly, there are subtle differences in reaction rates according to the isotopic mass, McKeegan said.

"We found that the Earth and moon, as well as Martian and other meteorites, which are samples of asteroids, have a lower concentration of the O-16 than does the sun," McKeegan said. "The implication is that we did not form out of the same solar nebula materials that created the sun. Just how and why remains to be discovered."

McKeegan and his colleagues measured, for the first time, the isotopic composition of oxygen in the solar wind. They found that the sun has about 6 percent more O-16 -- relative to both of the minor oxygen isotopes -- than Earth does. Because the sun represents the "starting composition of the entire solar system," these findings are surprising, McKeegan said.

"It's the most abundant element in the Earth, and it is isotopically anomalous," he said, adding that something chemically unusual happened to the material that eventually formed Earth and other rocky planets some 4.6 billion years ago, after the sun had already formed.

"The present composition of the rocky planets is quite different from the starting composition in a way we do not fully understand," he said, "but it must have involved interesting chemistry before the planets formed in the gaseous nebula that produced the sun and planets."

The data were obtained from an analysis of material ejected from the outer portion of the sun. That material can be thought of as a "fossil of our nebula" because scientific evidence suggests that the sun's outer layer has not changed measurably in billions of years. The sample of solar material collected by Genesis was small, but there was enough to be analyzed using UCLA's MegaSIMS (secondary ion mass spectrometer).

"This is the first time the heavy elements in the sun have had their isotope composition determined with precision, directly from solar material," McKeegan said. "The Genesis mission was a success. The mission has achieved its highest priority objectives. We are learning how planets form."

Analyses of meteorites from Mars indicate that oxygen on Mars is very similar to oxygen on Earth, but not identical, McKeegan said.

Genesis launched in August 2001. The spacecraft traveled to the L1 Lagrange Point, about 1 million miles from Earth, where it remained for 886 days between 2001 and 2004, passively collecting solar wind samples.

On Sept. 8, 2004, the spacecraft released a sample return capsule that entered Earth's atmosphere. Although the capsule made a hard landing -- the result of a failed parachute -- in the Utah Test and Training Range in Dugway, Utah, it marked NASA's first sample return since the final Apollo lunar mission in 1972 and the first material collected beyond the moon.

Co-authors of the oxygen study included Veronika Heber, a UCLA research scientist in the Department of Earth and Space Sciences; George Jarzebinski, senior electronics engineer at UCLA; Chris Coath, a former UCLA researcher who designed the ion optics of the MegaSIMS; Peter Mao, a former UCLA researcher who is currently an astrophysicist at the California Institute of Technology; Antti Kallio, a former UCLA postdoctoral scholar who acquired much of the solar wind data; Takaya Kunihiro, a former UCLA postdoctoral scholar currently at Japan's Okayama University; and Don Burnett, a professor at the California Institute of Technology, who was Genesis' principal investigator. A team from Los Alamos National Laboratory led by Roger Wiens built a device on the Genesis spacecraft for the analysis of oxygen and nitrogen from the solar wind. Wiens and his colleagues are also co-authors of the study. NASA funded the research.

"The sun houses more than 99 percent of the material currently in our solar system, so it's a good idea to get to know it better," Burnett said.

A second paper in Science by different researchers details differences between the sun and planets with regard to the element nitrogen. Like oxygen, nitrogen has one isotope (N-14) that makes up nearly 100 percent of the nitrogen atoms in the solar system, but there is also a tiny amount of N-15.

Researchers studying the same Genesis samples found that compared to Earth's atmosphere, nitrogen in the sun and Jupiter had slightly more N-14 -- but 40 percent less N-15. The sun and Jupiter appear to have the same nitrogen composition, but as with oxygen, the nitrogen composition of Earth and the rest of the inner solar system is very different.

"These findings show that all solar system objects, including the terrestrial planets, meteorites and comets, are anomalous compared to the initial composition of the nebula from which the solar system formed," said Bernard Marty, a Genesis co-investigator from the Centre de Recherches Pétrographiques et Géochimiques in France and lead author of the second Science study. "Understanding the cause of such a heterogeneity will impact our view on the formation of the solar system."

The Jet Propulsion Laboratory in Pasadena, Calif., managed the Genesis mission for NASA's Science Mission Directorate in Washington, D.C. Genesis was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver developed and operated the spacecraft. Analysis at the Centre de Recherches Pétrographiques et Géochimiques was supported by the Centre National d'Etudes Spatiales and the Centre National de la Recherche Scientifique, both in Paris.

For more information on the Genesis mission, visit http://genesismission.jpl.nasa.gov.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California - Los Angeles. The original article was written by Stuart Wolpert.

Journal References:

K. D. McKeegan, A. P. A. Kallio, V. S. Heber, G. Jarzebinski, P. H. Mao, C. D. Coath, T. Kunihiro, R. C. Wiens, J. E. Nordholt, R. W. Moses, D. B. Reisenfeld, A. J. G. Jurewicz, D. S. Burnett. The Oxygen Isotopic Composition of the Sun Inferred from Captured Solar Wind. Science, 2011; 332 (6037): 1528 DOI: 10.1126/science.1204636B. Marty, M. Chaussidon, R. C. Wiens, A. J. G. Jurewicz, D. S. Burnett. A 15N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples. Science, 2011; 332 (6037): 1533 DOI: 10.1126/science.1204656

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View the original article here

Free-floating planets may be more common than stars

ScienceDaily (May 18, 2011) — Astronomers, including a NASA-funded team member, have discovered a new class of Jupiter-sized planets floating alone in the dark of space, away from the light of a star. The team believes these lone worlds were probably ejected from developing planetary systems.

The discovery is based on a joint Japan-New Zealand survey that scanned the center of the Milky Way galaxy during 2006 and 2007, revealing evidence for up to 10 free-floating planets roughly the mass of Jupiter. The isolated orbs, also known as orphan planets, are difficult to spot, and had gone undetected until now. The newfound planets are located at an average approximate distance of 10,000 to 20,000 light-years from Earth.

"Although free-floating planets have been predicted, they finally have been detected, holding major implications for planetary formation and evolution models," said Mario Perez, exoplanet program scientist at NASA Headquarters in Washington.

The discovery indicates there are many more free-floating Jupiter-mass planets that can't be seen. The team estimates there are about twice as many of them as stars. In addition, these worlds are thought to be at least as common as planets that orbit stars. This would add up to hundreds of billions of lone planets in our Milky Way galaxy alone.

"Our survey is like a population census," said David Bennett, a NASA and National Science Foundation-funded co-author of the study from the University of Notre Dame in South Bend, Ind. "We sampled a portion of the galaxy, and based on these data, can estimate overall numbers in the galaxy."

The study, led by Takahiro Sumi from Osaka University in Japan, appears in the May 19 issue of the journal Nature.

The survey is not sensitive to planets smaller than Jupiter and Saturn, but theories suggest lower-mass planets like Earth should be ejected from their stars more often. As a result, they are thought to be more common than free-floating Jupiters.

Previous observations spotted a handful of free-floating, planet-like objects within star-forming clusters, with masses three times that of Jupiter. But scientists suspect the gaseous bodies form more like stars than planets. These small, dim orbs, called brown dwarfs, grow from collapsing balls of gas and dust, but lack the mass to ignite their nuclear fuel and shine with starlight. It is thought the smallest brown dwarfs are approximately the size of large planets.

On the other hand, it is likely that some planets are ejected from their early, turbulent solar systems, due to close gravitational encounters with other planets or stars. Without a star to circle, these planets would move through the galaxy as our sun and other stars do, in stable orbits around the galaxy's center. The discovery of 10 free-floating Jupiters supports the ejection scenario, though it's possible both mechanisms are at play.

"If free-floating planets formed like stars, then we would have expected to see only one or two of them in our survey instead of 10," Bennett said. "Our results suggest that planetary systems often become unstable, with planets being kicked out from their places of birth."

The observations cannot rule out the possibility that some of these planets may have very distant orbits around stars, but other research indicates Jupiter-mass planets in such distant orbits are rare.

The survey, the Microlensing Observations in Astrophysics (MOA), is named in part after a giant wingless, extinct bird family from New Zealand called the moa. A 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand is used to regularly scan the copious stars at the center of our galaxy for gravitational microlensing events. These occur when something, such as a star or planet, passes in front of another, more distant star. The passing body's gravity warps the light of the background star, causing it to magnify and brighten. Heftier passing bodies, like massive stars, will warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less.

A second microlensing survey group, the Optical Gravitational Lensing Experiment (OGLE), contributed to this discovery using a 4.2-foot (1.3 meter) telescope in Chile. The OGLE group also observed many of the same events, and their observations independently confirmed the analysis of the MOA group.

NASA's Jet Propulsion Laboratory, Pasadena,Calif., manages NASA's Exoplanet Exploration program office. JPL is a division of the California Institute of Technology in Pasadena.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Jet Propulsion Laboratory.

Journal Reference:

T. Sumi, K. Kamiya, D. P. Bennett, I. A. Bond, F. Abe, C. S. Botzler, A. Fukui, K. Furusawa, J. B. Hearnshaw, Y. Itow, P. M. Kilmartin, A. Korpela, W. Lin, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, M. Motomura, Y. Muraki, M. Nagaya, S. Nakamura, K. Ohnishi, T. Okumura, Y. C. Perrott, N. Rattenbury, To. Saito, T. Sako, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, P. C. M. Yock, A. Udalski, M. K. Szymanski, M. Kubiak, G. Pietrzynski, R. Poleski, I. Soszynski, L. Wyrzykowski, K. Ulaczyk. Unbound or distant planetary mass population detected by gravitational microlensing. Nature, 2011; 473 (7347): 349 DOI: 10.1038/nature10092

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View the original article here

New SETI survey focuses on Kepler's top Earth-like planets

ScienceDaily (May 16, 2011) — Now that NASA's Kepler space telescope has identified 1,235 possible planets around stars in our galaxy, astronomers at the University of California, Berkeley, are aiming a radio telescope at the most Earth-like of these worlds to see if they can detect signals from an advanced civilization.

The search began on May 8, when the Robert C. Byrd Green Bank Telescope -- the largest steerable radio telescope in the world -- dedicated an hour to eight stars with possible planets. Once UC Berkeley astronomers acquire 24 hours of data on a total of 86 Earth-like planets, they'll initiate a coarse analysis and then, in about two months, ask an estimated 1 million SETI@home users to conduct a more detailed analysis on their home computers.

"It's not absolutely certain that all of these stars have habitable planetary systems, but they're very good places to look for ET," said UC Berkeley graduate student Andrew Siemion.

The Green Bank telescope will stare for about five minutes at stars in the Kepler survey that have a candidate planet in the star's habitable zone -- that is, the planet has a surface temperature at which liquid water could be maintained.

"We've picked out the planets with nice temperatures -- between zero and 100 degrees Celsius -- because they are a lot more likely to harbor life," said physicist Dan Werthimer, chief scientist for SETI@home and a veteran SETI researcher.

Werthimer leads a 30-year-old SETI project on the world's largest radio telescope, the Arecibo receiver in Puerto Rico, which feeds data to SETI@home for a detailed analysis that could only be done on the world's largest distributed computer. He was involved in an early SETI project with the previous Green Bank telescope, which collapsed in 1988, as well as with the Allen Telescope Array (ATA) , which also conducted a broader search for intelligent signals from space run by the SETI Institute of Mountain View, Calif. The ATA went into hibernation mode last month after the SETI Institute and UC Berkeley ran out of money to operate it.

"With Arecibo, we focus on stars like our sun, hoping that they have planets around them that emit intelligent signals," Werthimer said. "But we've never had a list of planets like this before."

The radio dish in rural West Virginia was needed for the new search because the Arecibo dish cannot view the area of the northern sky on which Kepler focuses. But the Green Bank telescope also offers advantages over Arecibo. UC Berkeley's SETI observations piggyback on other astronomical observations at Arecibo, and is limited in the wavelength range it can observe, which centers on the 21 centimeter (1420 MHz) line where hydrogen emits light. These wavelengths easily pass through the dust clouds that obscure much of the galaxy.

"Searching for ET around the 21 centimeter line works if civilizations are broadcasting intentionally, but what if planets are leaking signals like 'I Love Lucy'?" Werthimer said. "With a new data recorder on the Green Bank telescope, we can scan a 800 megaHertz range of frequencies simultaneously, which is 300 times the range we can get at Arecibo."

Thus, one day on the Green Bank telescope provides as much data as one year's worth of observations at Arecibo: about 60 terabytes (60,000 gigabytes) in all, Siemion said. If they recorded a similar chunk of the radio spectrum from Arecibo, SETI@home would be overwhelmed with data, since the Arecibo sky survey observes nearly full time for years on end.

"It's also great that we will completely span the water hole, a canonical place to look for intentional signals from intelligent civilizations," Siemion said.

The water hole is a relatively quiet region of the radio spectrum in the universe and a range of wavelengths not significantly absorbed by material between the stars and galaxies. The water hole is bounded on one end by the 21 cm emissions from neutral hydrogen and on the other by the 18 cm emissions from the hydroxyl ion (OH). Because life is presumed to require the existence of liquid water, and water is composed of hydrogen and hydroxyl, this range was dubbed the water hole and seen as a natural window in which water-based life forms would signal their existence. That makes the water hole is a favorite of SETI projects.

"This is an interesting place, perhaps a beacon frequency, to look for signals from extraterrestrial civilizations," Siemion added.

The 86 stars were chosen from the 1,235 candidate planetary systems -- called Kepler Objects of Interest, or KOIs with the help of Kepler team member Geoffrey Marcy, professor of astronomy at UC Berkeley. UC Berkeley's targets include the 54 KOIs identified by the Kepler team as being in the habitable temperature range and with sizes ranging from Earth-size to larger than Jupiter; 10 KOIs not on the Kepler team's habitable list but with orbits less than three times Earth's orbit and orbital periods greater than 50 days; and all systems with four or more possible planets.

After the Green Bank telescope has targeted each star, it will scan the entire Kepler field for signals from planets other than the 86 targets.

A coarse analysis of the data by Werthimer and his team will be followed by a more thorough analysis by SETI@home users, who will be able to see whether they are analyzing Green Bank data as opposed to Arecibo data. The complete analysis for intelligent signals could take a year, Werthimer said.

"If you extrapolate from the Kepler data, there could be 50 billion planets in the galaxy," he said. "It's really exciting to be able to look at this first batch of Earth-like planets."

The Green Bank telescope is operated by the National Radio Astronomy Observatory, with funds provided by the National Science Foundation (NSF). SETI@home is supported by NSF, NASA and private donations.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California - Berkeley.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

New SETI survey focuses on Kepler's top Earth-like planets

ScienceDaily (May 16, 2011) — Now that NASA's Kepler space telescope has identified 1,235 possible planets around stars in our galaxy, astronomers at the University of California, Berkeley, are aiming a radio telescope at the most Earth-like of these worlds to see if they can detect signals from an advanced civilization.

The search began on May 8, when the Robert C. Byrd Green Bank Telescope -- the largest steerable radio telescope in the world -- dedicated an hour to eight stars with possible planets. Once UC Berkeley astronomers acquire 24 hours of data on a total of 86 Earth-like planets, they'll initiate a coarse analysis and then, in about two months, ask an estimated 1 million SETI@home users to conduct a more detailed analysis on their home computers.

"It's not absolutely certain that all of these stars have habitable planetary systems, but they're very good places to look for ET," said UC Berkeley graduate student Andrew Siemion.

The Green Bank telescope will stare for about five minutes at stars in the Kepler survey that have a candidate planet in the star's habitable zone -- that is, the planet has a surface temperature at which liquid water could be maintained.

"We've picked out the planets with nice temperatures -- between zero and 100 degrees Celsius -- because they are a lot more likely to harbor life," said physicist Dan Werthimer, chief scientist for SETI@home and a veteran SETI researcher.

Werthimer leads a 30-year-old SETI project on the world's largest radio telescope, the Arecibo receiver in Puerto Rico, which feeds data to SETI@home for a detailed analysis that could only be done on the world's largest distributed computer. He was involved in an early SETI project with the previous Green Bank telescope, which collapsed in 1988, as well as with the Allen Telescope Array (ATA) , which also conducted a broader search for intelligent signals from space run by the SETI Institute of Mountain View, Calif. The ATA went into hibernation mode last month after the SETI Institute and UC Berkeley ran out of money to operate it.

"With Arecibo, we focus on stars like our sun, hoping that they have planets around them that emit intelligent signals," Werthimer said. "But we've never had a list of planets like this before."

The radio dish in rural West Virginia was needed for the new search because the Arecibo dish cannot view the area of the northern sky on which Kepler focuses. But the Green Bank telescope also offers advantages over Arecibo. UC Berkeley's SETI observations piggyback on other astronomical observations at Arecibo, and is limited in the wavelength range it can observe, which centers on the 21 centimeter (1420 MHz) line where hydrogen emits light. These wavelengths easily pass through the dust clouds that obscure much of the galaxy.

"Searching for ET around the 21 centimeter line works if civilizations are broadcasting intentionally, but what if planets are leaking signals like 'I Love Lucy'?" Werthimer said. "With a new data recorder on the Green Bank telescope, we can scan a 800 megaHertz range of frequencies simultaneously, which is 300 times the range we can get at Arecibo."

Thus, one day on the Green Bank telescope provides as much data as one year's worth of observations at Arecibo: about 60 terabytes (60,000 gigabytes) in all, Siemion said. If they recorded a similar chunk of the radio spectrum from Arecibo, SETI@home would be overwhelmed with data, since the Arecibo sky survey observes nearly full time for years on end.

"It's also great that we will completely span the water hole, a canonical place to look for intentional signals from intelligent civilizations," Siemion said.

The water hole is a relatively quiet region of the radio spectrum in the universe and a range of wavelengths not significantly absorbed by material between the stars and galaxies. The water hole is bounded on one end by the 21 cm emissions from neutral hydrogen and on the other by the 18 cm emissions from the hydroxyl ion (OH). Because life is presumed to require the existence of liquid water, and water is composed of hydrogen and hydroxyl, this range was dubbed the water hole and seen as a natural window in which water-based life forms would signal their existence. That makes the water hole is a favorite of SETI projects.

"This is an interesting place, perhaps a beacon frequency, to look for signals from extraterrestrial civilizations," Siemion added.

The 86 stars were chosen from the 1,235 candidate planetary systems -- called Kepler Objects of Interest, or KOIs with the help of Kepler team member Geoffrey Marcy, professor of astronomy at UC Berkeley. UC Berkeley's targets include the 54 KOIs identified by the Kepler team as being in the habitable temperature range and with sizes ranging from Earth-size to larger than Jupiter; 10 KOIs not on the Kepler team's habitable list but with orbits less than three times Earth's orbit and orbital periods greater than 50 days; and all systems with four or more possible planets.

After the Green Bank telescope has targeted each star, it will scan the entire Kepler field for signals from planets other than the 86 targets.

A coarse analysis of the data by Werthimer and his team will be followed by a more thorough analysis by SETI@home users, who will be able to see whether they are analyzing Green Bank data as opposed to Arecibo data. The complete analysis for intelligent signals could take a year, Werthimer said.

"If you extrapolate from the Kepler data, there could be 50 billion planets in the galaxy," he said. "It's really exciting to be able to look at this first batch of Earth-like planets."

The Green Bank telescope is operated by the National Radio Astronomy Observatory, with funds provided by the National Science Foundation (NSF). SETI@home is supported by NSF, NASA and private donations.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California - Berkeley.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Free-floating planets may be more common than stars

ScienceDaily (May 18, 2011) — Astronomers, including a NASA-funded team member, have discovered a new class of Jupiter-sized planets floating alone in the dark of space, away from the light of a star. The team believes these lone worlds were probably ejected from developing planetary systems.

The discovery is based on a joint Japan-New Zealand survey that scanned the center of the Milky Way galaxy during 2006 and 2007, revealing evidence for up to 10 free-floating planets roughly the mass of Jupiter. The isolated orbs, also known as orphan planets, are difficult to spot, and had gone undetected until now. The newfound planets are located at an average approximate distance of 10,000 to 20,000 light-years from Earth.

"Although free-floating planets have been predicted, they finally have been detected, holding major implications for planetary formation and evolution models," said Mario Perez, exoplanet program scientist at NASA Headquarters in Washington.

The discovery indicates there are many more free-floating Jupiter-mass planets that can't be seen. The team estimates there are about twice as many of them as stars. In addition, these worlds are thought to be at least as common as planets that orbit stars. This would add up to hundreds of billions of lone planets in our Milky Way galaxy alone.

"Our survey is like a population census," said David Bennett, a NASA and National Science Foundation-funded co-author of the study from the University of Notre Dame in South Bend, Ind. "We sampled a portion of the galaxy, and based on these data, can estimate overall numbers in the galaxy."

The study, led by Takahiro Sumi from Osaka University in Japan, appears in the May 19 issue of the journal Nature.

The survey is not sensitive to planets smaller than Jupiter and Saturn, but theories suggest lower-mass planets like Earth should be ejected from their stars more often. As a result, they are thought to be more common than free-floating Jupiters.

Previous observations spotted a handful of free-floating, planet-like objects within star-forming clusters, with masses three times that of Jupiter. But scientists suspect the gaseous bodies form more like stars than planets. These small, dim orbs, called brown dwarfs, grow from collapsing balls of gas and dust, but lack the mass to ignite their nuclear fuel and shine with starlight. It is thought the smallest brown dwarfs are approximately the size of large planets.

On the other hand, it is likely that some planets are ejected from their early, turbulent solar systems, due to close gravitational encounters with other planets or stars. Without a star to circle, these planets would move through the galaxy as our sun and other stars do, in stable orbits around the galaxy's center. The discovery of 10 free-floating Jupiters supports the ejection scenario, though it's possible both mechanisms are at play.

"If free-floating planets formed like stars, then we would have expected to see only one or two of them in our survey instead of 10," Bennett said. "Our results suggest that planetary systems often become unstable, with planets being kicked out from their places of birth."

The observations cannot rule out the possibility that some of these planets may have very distant orbits around stars, but other research indicates Jupiter-mass planets in such distant orbits are rare.

The survey, the Microlensing Observations in Astrophysics (MOA), is named in part after a giant wingless, extinct bird family from New Zealand called the moa. A 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand is used to regularly scan the copious stars at the center of our galaxy for gravitational microlensing events. These occur when something, such as a star or planet, passes in front of another, more distant star. The passing body's gravity warps the light of the background star, causing it to magnify and brighten. Heftier passing bodies, like massive stars, will warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less.

A second microlensing survey group, the Optical Gravitational Lensing Experiment (OGLE), contributed to this discovery using a 4.2-foot (1.3 meter) telescope in Chile. The OGLE group also observed many of the same events, and their observations independently confirmed the analysis of the MOA group.

NASA's Jet Propulsion Laboratory, Pasadena,Calif., manages NASA's Exoplanet Exploration program office. JPL is a division of the California Institute of Technology in Pasadena.

More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Jet Propulsion Laboratory.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Huge dry ice deposit on Mars: NASA orbiter reveals big changes in Red Planet's atmosphere

ScienceDaily (Apr. 22, 2011) — NASA's Mars Reconnaissance Orbiter has discovered the total amount of atmosphere on Mars changes dramatically as the tilt of the planet's axis varies. This process can affect the stability of liquid water, if it exists on the Martian surface, and increase the frequency and severity of Martian dust storms.

Researchers using the orbiter's ground-penetrating radar identified a large, buried deposit of frozen carbon dioxide, or dry ice, at the Red Planet's south pole. The scientists suspect that much of this carbon dioxide enters the planet's atmosphere and swells the atmosphere's mass when Mars' tilt increases. The findings are published in the journal Science.

The newly found deposit has a volume similar to Lake Superior's nearly 3,000 cubic miles (about 12,000 cubic kilometers). The deposit holds up to 80 percent as much carbon dioxide as today's Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars' atmosphere is about 95 percent carbon dioxide, in contrast to Earth's much thicker atmosphere, which is less than .04 percent carbon dioxide.

"We already knew there is a small perennial cap of carbon-dioxide ice on top of the water ice there, but this buried deposit has about 30 times more dry ice than previously estimated," said Roger Phillips of Southwest Research Institute in Boulder, Colo. Phillips is deputy team leader for the Mars Reconnaissance Orbiter's Shallow Radar instrument and lead author of the report.

"We identified the deposit as dry ice by determining the radar signature fit the radio-wave transmission characteristics of frozen carbon dioxide far better than the characteristics of frozen water," said Roberto Seu of Sapienza University of Rome, team leader for the Shallow Radar and a co-author of the new report. Additional evidence came from correlating the deposit to visible sublimation features typical of dry ice.

"When you include this buried deposit, Martian carbon dioxide right now is roughly half frozen and half in the atmosphere, but at other times it can be nearly all frozen or nearly all in the atmosphere," Phillips said.

An occasional increase in the atmosphere would strengthen winds, lofting more dust and leading to more frequent and more intense dust storms. Another result is an expanded area on the planet's surface where liquid water could persist without boiling. Modeling based on known variation in the tilt of Mars' axis suggests several-fold changes in the total mass of the planet's atmosphere can happen on time frames of 100,000 years or less.

The changes in atmospheric density caused by the carbon-dioxide increase also would amplify some effects of the changes caused by the tilt. Researchers plugged the mass of the buried carbon-dioxide deposit into climate models for the period when Mars' tilt and orbital properties maximize the amount of summer sunshine hitting the south pole. They found at such times, global, year-round average air pressure is approximately 75 percent greater than the current level.

"A tilted Mars with a thicker carbon-dioxide atmosphere causes a greenhouse effect that tries to warm the Martian surface, while thicker and longer-lived polar ice caps try to cool it," said co-author Robert Haberle, a planetary scientist at NASA's Ames Research Center in Moffett Field, Calif. "Our simulations show the polar caps cool more than the greenhouse warms. Unlike Earth, which has a thick, moist atmosphere that produces a strong greenhouse effect, Mars' atmosphere is too thin and dry to produce as strong a greenhouse effect as Earth's, even when you double its carbon-dioxide content."

The Shallow Radar, one of the Mars Reconnaissance Orbiter's six instruments, was provided by the Italian Space Agency, and its operations are led by the Department of Information Engineering, Electronics and Telecommunications at Sapienza University of Rome. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter project for NASA's Science Mission Directorate at the agency's headquarters in Washington. Lockheed Martin Space Systems in Denver built the spacecraft.

For more information about the Mars Reconnaissance Orbiter mission, visit http://www.nasa.gov/mro .

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Jet Propulsion Laboratory.

Journal Reference:

Roger J. Phillips, Brian J. Davis, Kenneth L. Tanaka, Shane Byrne, Michael T. Mellon, Nathaniel E. Putzig, Robert M. Haberle, Melinda A. Kahre, Bruce A. Campbell, Lynn M. Carter, Isaac B. Smith, John W. Holt, Suzanne E. Smrekar, Daniel C. Nunes, Jeffrey J. Plaut, Anthony F. Egan, Timothy N. Titus, and Roberto Seu. Massive CO2 Ice Deposits Sequestered in the South Polar Layered Deposits of Mars. Science, 2011; DOI: 10.1126/science.1203091

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here