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  • richardmitnick 11:56 am on May 16, 2016 Permalink | Reply
    Tags: , , Exoplanets, , Recent Kepler release of planets   

    From INVERSE: “Identify 1,284 New Exoplanets in One Fell Swoop” 

    INVERSE

    INVERSE

    May 12, 2016
    Neel V. Patel

    Before Tuesday, there were no shortage of theories about what NASA’s discovery announcement would entail. (Full disclosure: I was responsible for much of that speculation.) Then Tuesday hit and we found out exactly what the big news was: NASA scientists just confirmed the identify of 1,284 new exoplanets in the universe — including nine planets that have the potential to be habitable to life.

    It’s an announcement that has already inspired scientists and ordinary individuals around the world to ponder whether we might seriously find extraterrestrial life soon enough. But the new study raises an interesting question: what changed between the last few years and now that allowed scientists to identify so many new exoplanets all at once? Did all of these planets just show up at once? Did we develop better technology? Did the Kepler Space Telescope miraculously get better (after weirdly almost breaking down)? What gives?

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    The answer: It all comes down to a new method of validating exoplanet candidates that provides ”astrophysical false positive probability calculations” for such objects, according to a new paper* published in the latest issue of The Astrophysical Journal. Basically, the new method ascribes a number to every object found by Kepler that determines the likelihood that object is an exoplanet, and not an “imposter.” Call it a planet score. The higher the number, the more likely it’s a planet.

    The new method only allows an object to move from the “candidate” category to “exoplanet” if Kepler researchers can say so with 99 percent reliability or higher.

    1
    This is an artist’s conception of Kepler-20e, the first planet smaller than the Earth discovered to orbit a star other than the sun. A year on Kepler-20e only lasts six days, as it is much closer to its host star than the Earth is to the sun.

    We should slow down at this point and expound on exactly how astronomers find and evaluate potential exoplanets. Basically, through Kepler and a few other instruments**, scientists stare at distant stars and measure the brightness of light emitting from those balls of fiery energy. When a star has a planet in orbit, its brightness will dim as that planet transits past it in relation to the telescope we’re using to watch it (a recent, albeit small, example is Mercury passing in front of the sun). As long as that dimming isn’t just a technical error, it’s a sign that something is passing through the neighborhood. A consistent dimming occurring regularly over time is further evidence it might be a planet.

    In the past, scientists had to pore over the brightness numbers along with assessing a variety of different data that might be attainable, like radio velocity observation or high-resolution imaging. Unfortunately, doing that kind of work is extremely time consuming, and we don’t always have the resources to find what we need.

    So in this day-and-age, we turn to computers for help. Timothy Morton, a Princeton researcher who studies exoplanets, developed a new method for exoplanet validation that combines previous exoplanet observations and the current brightness measurements scientists are gathering with Kepler.

    There are two kinds of simulations. The first looks at how the dimming compares to that from known exoplanets and imposter objects. The second goes a step further and deduces whether dimming is indicative of exoplanet behavior given what we already about how exoplanets are distributed and laid around the Milky Way.

    The two simulations are used to determine the statistical likelihood the object in question is an exoplanet. It’s a faster way of doing this work — and by all accounts, it’s even more accurate. In fact, the method is actually being used to verify previously confirmed exoplanets and determine whether they might actually be false-positives.

    This is crucial for the direction of future exoplanet research. The work accomplished since Kepler’s launch in 2009 has been huge in illustrating just how many other worlds exist in the universe — and it has given humans a staggering amount of hope we may find another habitable planet, or even alien life.

    NASA is already getting ready to launch the Transiting Exoplanet Survey Satellite (TESS) in late 2017, and the James Webb Space Telescope in 2018.

    NASA/TESS
    NASA/TESS

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    Both will play a pivotal role in exoplanet investigations by acquiring lots more data that we’ve ever dealt with. Morton’s model will help our scientists on the ground sift through that data and identify potentially habitable exoplanets faster than we could have hoped.

    Photos via NASA/Ames/JPL-Caltech, NASA/JPL-Caltech

    *SCience paper:
    FALSE POSITIVE PROBABILITIES FOR ALL KEPLER OBJECTS OF INTEREST: 1284 NEWLY VALIDATED PLANETS AND 428 LIKELY FALSE POSITIVES

    **The only other telescope that is specifically referenced, NASA/Spitzer, is referenced in the Science paper.

    NASA/Spitzer Telescope
    NASA/Spitzer Telescope

    See the full article here .

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  • richardmitnick 5:40 pm on April 17, 2016 Permalink | Reply
    Tags: , , Exoplanets,   

    From CNN: “The planet hunter searching for another Earth” Sara Seager 

    1
    CNN

    April 15, 2016
    Jacopo Prisco

    “I want to find another Earth. That’s what I’m living for.”
    MIT astrophysicist Sara Seager has been looking at planets beyond our solar system, known as exoplanets, for almost 20 years.
    When the first ones were discovered in the 1990s, many questioned the finding and didn’t think it was real. But since then, with better technology, we have observed more than 6,000 of them, most of which are giant balls of gas.

    Today, the list grows every week.

    With so many planets now coming out of hiding, the race is on to identify one that resembles Earth: a rocky world with liquid water just like ours, and suitable to host life.
    Seager believes she knows how to make that discovery.

    ‘These aren’t planets!’

    It’s not easy to see exoplanets as you can’t just look at them through a telescope. This is due to the blinding light coming from their host stars, which can be very different in size and features compared to our sun. The process is often described as trying to spot a firefly circling a lighthouse, from thousands of miles away.

    The first ones were discovered indirectly, in 1995, by just looking at stars to see if they would wobble slightly, responding to the pull of another object’s gravity.

    At this time, Seager was a graduate student at Harvard searching for a topic for her Ph.D. and she was intrigued by the newborn field of faraway planets.
    “Since the planets were discovered indirectly, most people didn’t believe that the discoveries were real. They’d say to me ‘Why are you doing this? These aren’t planets!’,” says Seager.
    The contrarians weren’t entirely wrong: the wobble can be caused by other factors such as another star and several planet discoveries have been retracted over time for this reason.
    But then a different technique was found to make their hunt easier, called transit.

    Planet transit. NASA
    Planet transit. NASA

    This is when a planet moves in front of its host star and causes the star’s light to dim slightly.

    “One of the planets from the wobble technique showed transit: it went in front of the star at exactly the time it was predicted to and that was basically incontrovertible,” says Seager.
    Exoplanets were real.

    1
    Dwarfing even Jupiter – HD-106906b is a gaseous planet 11 times more massive than Jupiter. The planet is believed to have formed in the center of its solar system, before being sent flying out to the edges of the region by a violent gravitational event. No image credit.

    Alien atmospheres

    Seager did not want to simply look for distant planets. She set her sights on something more specific — their atmosphere. She was the first person to do so.
    “Atmospheres are important because they’re a way to look for signs of life: we look at gases that don’t belong and may have been produced by some life form,” she explains.
    But if seeing an exoplanet is already difficult, how do you observe an atmosphere? For this purpose the light from the star can come in handy. “When a planet transits in front of its star, we can very carefully analyze the atmosphere’s composition, thanks to the light of the star shining through it,” says Seager.

    The process becomes similar to looking at a rainbow.
    “If you look at a rainbow very closely, you see tiny little dark lines between the colors, pieces that are missing. Those lines are there because Earth’s atmosphere is taking away some of the light.”
    The dark lines are like fingerprints for specific gases and special tools can decode which ones are there. In 1999, Seager suggested that one particular element, sodium, should leave a detectable fingerprint.
    “It’s like skunk spray: a tiny bit of sodium can make a very big signature,” she says.

    Seager was right — her prediction was independently confirmed two years later using the Hubble telescope.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Sodium was found in the atmosphere of a “Hot Jupiter,” the name given to the first exoplanets ever discovered. These are huge spheres of gas many times larger than Earth — like our Jupiter — orbiting dangerously close to their stars, making them very hot.
    Because of their size, Hot Jupiters are the easiest exoplanets to spot, and hundreds have been found to date. But as they don’t have a solid surface, they are nothing like Earth.
    To find life, we need small, rocky planets — like ours.

    The Goldilocks Zone

    Compared to finding “Hot Jupiters”, searching for rocky planets is far more difficult, mainly because of their smaller size. And when spotting gases, it’s not sodium we’re after.

    “The number one thing we want to see in a planet’s atmosphere is water vapor,” says Seager.
    We see water vapour in some of the giant planets, like Jupiter, as they have it naturally within their atmosphere. “We have not seen that yet in a rocky planet.”
    Detecting water vapor on a rocky planet would be the tell-tale sign of a liquid ocean, and therefore the potential for life. “All life on Earth needs water, and we believe that all life needs a liquid,” says Seager.
    The need for liquid to create life is theorized due to the chemistry of molecules, as they require liquids to react and reform into other things — such as lifeforms. “Water is simply the most abundant liquid out there,” says Seager.
    For a planet to have liquid water, some basic conditions must be met. The planet must be such that its surface temperature is not too hot — or water will boil away — and not too cold — or it will freeze into ice. This all depends on its distance from the parent star: either too close, or too far.
    Astronomers call this sweet spot the “Goldilocks zone,” from the children’s tale “The Three Bears,” in which young Goldilocks likes her porridge “Not too cold, not too hot, but just right.”

    Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo
    Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo.

    These planets are not rare, but the challenge in spotting them can make it seem that way.
    “As many as one in five stars like the sun could have a planet with liquid water. And even though this number could be wrong, as things change quickly, we know for sure that small rocky planets are not rare,” says Seager.
    There may be billions of Earth-like planets in our galaxy alone.

    The galaxy’s finest

    Out of the 6,000 planets discovered so far, approximately 2,000 have been confirmed to be actual planets — work is underway on the rest — but only about 30 are considered potentially habitable.

    In 2014, NASA found the first Earth-sized planet orbiting a star in the habitable zone. This was named Kepler-186f — after the Kepler space telescope, used to spot it — and is about 500 light-years away in the constellation Cygnus, the galactic equivalent of our neighbourhood since the Milky Way is about 100,000 light years across.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    This planet is 10% larger than Earth.
    Described by NASA as “a significant step toward finding worlds like our planet Earth,” Kepler-186f orbits around a type of common star known as a red dwarf, which is about half the size of our sun.
    Then, in 2015, astronomers found the first Earth-like planet orbiting a star just like our sun, called Kepler-452b. This was dubbed Earth’s “bigger, older cousin,” as the planet is 60% larger than Earth and completes one orbit in 385 days, making its years remarkably close to our own
    With our current technology, however, it’s hard to know much more than the size of an exoplanet and how far it is from its star.
    But that’s about to change.

    New eyes in the sky

    The majority of exoplanet discoveries have been made by the Kepler space telescope, after which most of them have been named. Launched in 2009, the telescope has now entered emergency mode 75 million miles away from Earth, due to a malfunction.
    To study the atmospheres of potential Earth twins, scientists need new eyes in the sky.
    To date, Seager has only been able to study the atmospheres of a handful of exoplanets — all gas giants — but she’s involved in a new NASA program launching in 2017 to just scout the brightest nearby stars for small rocky planets in the habitable zone.


    Access mp4 video here .

    Called TESS (Transiting Exoplanet Survey Satellite), the two-year mission will accumulate data that will then be fed into the James Webb Space Telescope, the next Hubble, which is due to launch in 2018: “It’s going to be amazing,” says Seager.

    NASA/TESS
    NASA/TESS

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    The James Webb telescope — named after the head of NASA during the pioneering era of the 1960s — will look at the cosmos with unprecedented clarity thanks to its use of a primary mirror about five times larger than Hubble’s. It will also offer direct imaging of exoplanets by blocking the blinding light of their host stars with special instruments that make them more visible. This will allow Seager and other astronomers to study exoplanets like never before.
    Seager believes many of the planets in their search will be the rocky, watery worlds she’s been looking for.
    “I’m absolutely confident they’re out there.”

    See the full article here .

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  • richardmitnick 6:31 pm on April 11, 2016 Permalink | Reply
    Tags: , , , Exoplanets   

    From Carnegie: “New tool refines exoplanet search” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    April 11, 2016
    No writer credit found

    Planet-hunting is an ongoing process that’s resulting in the discovery of more and more planets orbiting distant stars. But as the hunters learn more about the variety among the tremendous number of predicted planets out there, it’s important to refine their techniques. New work led by Carnegie’s Jonathan Gagné, Caltech’s Peter Gao, and Peter Plavchan from Missouri State University reports on a technological upgrade for one method of finding planets or confirming other planetary detections. The result is published by The Astrophysical Journal.

    One of the most-popular and successful techniques for finding and confirming planets is called the radial velocity method. A planet is obviously influenced by the gravity of the star it orbits; that’s what keeps it in orbit. This technique takes advantage of the fact that the planet’s gravity also affects the star in return. As a result, astronomers are able to detect the tiny wobbles the planet induces as its gravity tugs on the star. Using this method, astronomers have detected hundreds of exoplanets.

    For certain kinds of low-mass stars, however, there are limitations to the standard radial velocity method, which can cause false positives—in other words, find something that looks like a planet, but isn’t.

    To address this issue, Gagné, Gao, and Plavchan decided to use the radial velocity technique, but they examined a different, longer wavelength of light.

    “Switching from the visible spectrum to the near-infrared, the wobble effect caused by an orbiting planet will remain the same regardless of wavelength,” Gagné explained. “But looking in the near-infrared will allow us to reject false positives caused by sunspots and other phenomena that will not look the same in near-infrared as they do in visible light,”

    Radial velocity work in the near-infrared wavelengths has been conducted before, but it has trailed behind planet hunting in the visible spectrum, partially due to technical challenges. The research team was able to develop a better calibration tool to improve the overall technology for near-infrared radial velocity work, which should make it a better option going forward.

    They examined 32 low-mass stars using this technological upgrade at the NASA Infrared Telescope Facility atop Mauna Kea, Hawaii.

    NASA Infrared Telescope facility
    NASA Infrared Telescope facility Mauna Kea Hawaii USA

    Their findings confirmed several known planets and binary systems, and also identified a few new planetary candidates.

    “Our results indicate that this planet-hunting tool is precise and should be a part of the mix of approaches used by astronomers going forward,” Gao said. “It’s amazing to think that two decades ago we’d only just confirmed exoplanets actually existed and now we’re able to refine and improve those methods for further discoveries.”

    Carnegie planet hunting tool cell that contains methane gas
    Carnegie planet hunting tool cell that contains methane gas

    Other members of the team were: Guillem Anglada-Escude of University of London and the Centre for Astrophysics Research; Elise Furlan, Carolyn Brinkworth, Chas Beichman, and David Ciardi of the NASA Exoplanet Science Institute (Brinkworth also of the National Center for Atmospheric Research); Cassy Davison, Todd Henry, and Russel White of Georgia State University; Angelle Tanner of Mississippi State University; Adric Riedel and Michael Bottom of the California Institute of Technology; David Latham and John Johnson of the Harvard-Smithsonian Center for Astrophysics; Sean Mills of University of Chicago; Kent Wallace, Bertrand Mennesson, Gautam Vasisht, and Timothy Crawford of the Jet Propulsion Laboratory; Kaspar Von Braun and Lisa Prato of Lowell Observatory; Stephen Kane of San Francisco State University; Eric Mamajek of University of Rochester; Bernie Walp of the NASA Dryden Flight Research Center; Raphael Rougeot of the Euroopean Space Research and Technology Centre; Claire Geneser of Missouri State; and Joseph Catanzarite of NASA Ames Research Center.

    This work was supported by an Infrared Processing and Analysis Center (IPAC) fellowship, a grant from the Fond de Recherche Québécois – Nature et Technologie and the Natural Science, a grant from the Engineering Research Council of Canada, an iREx postdoctoral Fellowship, and a JPL Research and Technology Development Grant. This work was performed in part under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by the National Aeronautics and Space Administration (NASA) through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

    See the full article here .

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

     
  • richardmitnick 2:04 pm on March 15, 2016 Permalink | Reply
    Tags: , , Exoplanets,   

    From phys.org: “Four new giant planets detected around giant stars” 

    physdotorg
    phys.org

    March 15, 2016
    Tomasz Nowakowski

    Gas giants
    Artist’s concept of a giant extrasolar planet. Credit: NASA/JPL-Caltech.

    An international team of astronomers reports the discovery of four new giant exoplanets orbiting stars much bigger than our sun. The newly detected alien worlds are enormous, with masses from 2.4 to 5.5 the mass of Jupiter and have very long orbital periods ranging from nearly two to slightly more than four Earth years. The findings were published on Mar. 11 in a research paper available online at arXiv.org.

    The team, led by Matias Jones of the Pontifical Catholic University of Chile, made the discovery during observations under the EXPRESS (EXoPlanets aRound Evolved StarS) radial velocity program. They used two telescopes located in the Atacama desert in Chile: the 1.5 m telescope at the Cerro Tololo Inter-American Observatory and the 2.2 m telescope at La Silla observatory. Complementary observations were conducted at the 3.9 m Anglo-Australian telescope [AAT] in Australia.

    NOAO SMARTS
    NOAO /CTIO SMARTS CHIRON 1.5 meter telescope

    NOAO Cerro Tolo
    NOAO CTIO

    ESO 2.2 meter telescope
    ESO 2.2 meter telescope at La Silla

    ESO LaSilla
    La Silla

    AAO Anglo Australian Telescope Exterior
    AAO Anglo Australian Telescope Interior
    AAT

    Using spectrographs mounted on these telescopes, the researchers were monitoring a sample of 166 bright giant stars that are observable from the southern hemisphere. They took several spectra for each of the stars in the sample thanks to these instruments. The observation campaign lasted from 2009 to 2015.

    The astronomers have computed a series of precision radial velocities of four giant stars: HIP8541, HIP74890, HIP84056 and HIP95124. According to them, these velocities show periodic signal variations. The team concluded that the most probable explanation of the periodic radial velocity signals observed in these stars must be the presence of planetary companions.

    “These velocities show periodic signals, with semi-amplitudes between approximately 50 to 100 ms−1, which are likely caused by the doppler shift induced by orbiting companions. We performed standard tests (chromospheric emission, line bisector analysis and photometric variability) aimed at studying whether these radial velocity signals have an intrinsic stellar origin. We found no correlation between the stellar intrinsic indicator with the observed velocities,” the paper reads.

    HIP8541b is the most massive of the newly found quartet of planets. With a mass of about 5.5 Jupiter masses, this exoplanet also has a much longer orbital period than the other three worlds, equal to 1,560 days. Its parent star is slightly more massive than the sun and has a radius of nearly eight solar radii.

    HIP74890b and HIP84056b are very similar in terms of mass and orbital period. The mass of HIP74890b is estimated to be 2.4 Jupiter masses, what is about 92 percent of the mass of HIP84056b. The more massive planet of this comparable duo has an orbital period lasting nearly 819 days – about three fewer days than the other planet. Their host stars are also of similar mass and size, about 1.7 the mass of the sun, with a radius of 5.03 (HIP 84056) and 5.77 (HIP 74890) solar radii.

    Among the exoplanets described in the paper, the one with the shortest orbital period (562 days), is designated HIP95124b. It has a mass of 2.9 Jupiter masses and orbits a star nearly two times more massive than the sun, with a radius of 5.12 solar radii.

    The discovery of these planets also yielded interesting results about correlations between the stellar properties and the occurrence rate of planets. The researchers have found that giant planets are preferentially detected around metal-rich stars.

    “We also present a statistical analysis of the mass-metallicity correlations of the planet-hosting stars in our sample. (…) We show that the fraction of giant planets increases with the stellar mass in the range between 1 to 2.1 solar masses, despite the fact that planets are more easily detected around less massive stars,” the scientists noted.

    The team concluded that the high fraction of multiple systems observed in giant stars is a natural consequence of the planet formation mechanism around intermediate-mass stars.

    More information: Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars, arXiv:1603.03738 [astro-ph.EP] arxiv.org/abs/1603.03738

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 3:47 pm on March 9, 2016 Permalink | Reply
    Tags: , , Exoplanets,   

    From Kepler: “NASA’s K2 mission: The Kepler Space Telescope’s Second Chance to Shine” 

    NASA Kepler Logo

    NASA Kepler Telescope
    NASA/Kepler

    March 9, 2016
    Michele Johnson
    Ames Research Center, Moffett Field, Calif.
    650-604-6982
    michele.johnson@nasa.gov

    K2 How It Will Work
    K2 How It Will Work.
    Engineers developed an innovative way to stabilize and control the spacecraft. This technique of using the sun as the “third wheel” has Kepler searching for planets again, but also making discoveries on young stars to supernovae. Credits: NASA Ames/W Stenzel

    The engineers huddled around a telemetry screen, and the mood was tense. They were watching streams of data from a crippled spacecraft more than 50 million miles away – so far that even at the speed of light, it took nearly nine minutes for a signal to travel to the spacecraft and back.

    It was late August 2013, and the group of about five employees at Ball Aerospace in Boulder, Colorado, was waiting for NASA’s Kepler space telescope to reveal whether it would live or die. A severe malfunction had robbed the planet-hunting Kepler of its ability to stay pointed at a target without drifting off course.

    The engineers had devised a remarkable solution: using the pressure of sunlight to stabilize the spacecraft so it could continue to do science. Now, there was nothing more they could do but wait for the spacecraft to reveal its fate.

    “You’re not watching it unfold in real time,” said Dustin Putnam, Ball’s attitude control lead for Kepler. “You’re watching it as it unfolded a few minutes ago, because of the time the data takes to get back from the spacecraft.”

    Finally, the team received the confirmation from the spacecraft they had been waiting for. The room broke out in cheers. The fix worked! Kepler, with a new lease on life, was given a new mission as K2. But the biggest surprise was yet to come. A space telescope with a distinguished history of discovering distant exoplanets – planets orbiting other stars – was about to outdo even itself, racking up hundreds more discoveries and helping to usher in entirely new opportunities in astrophysics research.

    “Many of us believed that the spacecraft would be saved, but this was perhaps more blind faith than insight,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at NASA’s Ames Research Center in California’s Silicon Valley. “The Ball team devised an ingenious solution allowing the Kepler space telescope to shine again.”

    The discoveries roll in

    A little more than two years after the tense moment for the Ball engineers, K2 has delivered on its promise with a breadth of discoveries. Continuing the exoplanet-hunting legacy, K2 has discovered more than three dozen exoplanets and with more than 250 candidates awaiting confirmation. A handful of these worlds are near-Earth-sized and orbit stars that are bright and relatively nearby compared with Kepler discoveries, allowing scientists to perform follow-up studies. In fact, these exoplanets are likely future targets for the Hubble Space Telescope and the forthcoming James Webb Space Telescope (JWST), with the potential to study these planets’ atmospheres in search of signatures indicative of life.

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Webb telescope annotated
    NASA/ESA/CSA JWST

    K2 also has astronomers rethinking long-held planetary formation theory, and the commonly understood lonely “hot Jupiter” paradigm. The unexpected discovery of a star with a close-in Jupiter-sized planet sandwiched between two smaller companion planets now has theorists back at their computers reworking the models, and has sent astronomers back to their telescopes in search of other hot Jupiter companions.

    “It remains a mystery how a giant planet can form far out and migrate inward leaving havoc in its wake and still have nearby planetary companions,” said Barclay.

    Like its predecessor, K2 searches for planetary transits – the tiny, telltale dip in the brightness of a star as a planet crosses in front – and for the first time caught the rubble from a destroyed exoplanet transiting across the remains of a dead star known as a white dwarf. Exoplanets have long been thought to orbit these remnant stars, but not until K2 has the theory been confirmed.

    K2 has fixed its gaze on regions of the sky with densely packed clusters of stars which has revealed the first transiting exoplanet in such an area, popularly known as the Hyades star cluster. Clusters are exciting places to find exoplanets because stars in a cluster all form around the same time, giving them all the same “born-on” date. This helps scientists understand the evolution of planetary systems.

    The repurposed spacecraft boasts discoveries beyond the realm of exoplanets. Mature stars – about the age of our sun and older – largely populated the original single Kepler field of view. In contrast, many K2 fields see stars still in the process of forming. In these early days, planets also are assembled and by looking at the timescales of star formation, scientists gain insight into how our own planet formed.

    Studies of one star-forming region, called Upper Scorpius, compared the size of young stars observed by K2 with computational models. The result demonstrated fundamental imperfections in the models. While the reason for these discrepancies is still under debate, it likely shows that magnetic fields in stars do not arise as researchers expect.

    Looking in the ecliptic – the orbital path traveled around the sun by the planets of our solar system and the location of the zodiac – K2 also is well equipped to observe small bodies within our own solar system such as comets, asteroids, dwarf planets, ice giants and moons. Last year, for instance, K2 observed Neptune in a dance with its two moons, Triton and Nereid. This was followed by observations of Pluto and Uranus.

    “K2 can’t help but observe the dynamics of our planetary system, ” said Barclay. “We all know that planets follow laws of motion but with K2 we can see it happen.”

    These initial accomplishments have come in the first year and a half since K2 began in May 2014, and have been carried off without a hitch. The spacecraft continues to perform nominally.

    Searching for far out worlds

    In April, K2 will take part in a global experiment in exoplanet observation with a special observing period or campaign, Campaign 9. In this campaign, both K2 and astronomers at ground-based observatories on five continents will simultaneously monitor the same region of sky towards the center of our galaxy to search for small planets, such as the size of Earth, orbiting very far from their host star or, in some cases, orbiting no star at all.

    For this experiment, scientists will use gravitational microlensing – the phenomenon that occurs when the gravity of a foreground object, such as a planet, focuses and magnifies the light from a distant background star. This detection method will allow scientists to find and determine the mass of planets that orbit at great distances, like Jupiter and Neptune do our sun.

    Design by community

    What could turn out to be one of the most important legacies of K2 has little to do with the mechanics of the telescope, now operating on two wheels and with an assist from the sun.

    The Kepler mission was organized along traditional lines of scientific discovery: a targeted set of objectives carefully chosen by the science team to answer a specific question on behalf of NASA – how common or rare are “Earths” around other suns?

    K2’s modified mission involves a whole new approach– engaging the scientific community at large and opening up the spacecraft’s capabilities to a broader audience.

    “The new approach of letting the community decide the most compelling science targets we’re going to look at has been one of the most exciting aspects,” said Steve Howell, the Kepler and K2 project scientist at Ames. “Because of that, the breadth of our science is vast, including star clusters, young stars, supernovae, white dwarfs, very bright stars, active galaxies and, of course, exoplanets.”

    In the new paradigm, the K2 team laid out some broad scientific objectives for the mission and planned to operate the spacecraft on behalf of the community.

    Kepler’s field of view surveyed just one patch of sky in the northern hemisphere. The K2 ecliptic field of view provides greater opportunities for Earth-based observatories in both the northern and southern hemispheres, allowing the whole world to participate.

    With more than two years of fuel remaining, the spacecraft’s scientific future continues to look unexpectedly bright.

    For more information about the Kepler and K2 missions, visit:

    http://www.nasa.gov/kepler

    Authored by Michele Johnson and H. Pat Brennan/JPL

    See the full article here .

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    The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone→ and determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.
    The operations phase of the Kepler mission is managed for NASA by the Ames Research Center, Moffett Field, CA. NASA’s Jet Propulsion Laboratory (JPL), Pasadena, CA, managed the mission through development, launch and the start of science operations. Dr. William Borucki of NASA Ames is the mission’s Science Principal Investigator. Ball Aerospace and Technologies Corp., Boulder, CO, developed the Kepler flight system.

    In October 2009, oversight of the Kepler project was transferred from the Discovery Program at NASA’s Marshall Space Flight Center, Huntsville, AL, to the Exoplanet Exploration Program at JPL

    K2

    Extending Kepler’s power to the ecliptic

    The loss of a second of the four reaction wheels on board the Kepler spacecraft in May 2013 brought an end to Kepler’s four plus year science mission to continuously monitor more than 150,000 stars to search for transiting exoplanets. Developed over the months following this failure, the K2 mission represents a new concept for spacecraft operations that enables continued scientific observations with the Kepler space telescope. K2 became fully operational in June 2014 and is expected to continue operating until 2017 or 2018.

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  • richardmitnick 7:12 am on February 8, 2016 Permalink | Reply
    Tags: , Exoplanets,   

    From New Scientist: “How Do You Find an Exoplanet? An insider account gives top tips” 

    NewScientist

    New Scientist

    3 February 2016
    Lewis Dartnell

    ESO VLT
    Soon, Chile’s giant telescope will search for Earth-like exoplanets ESO/S. Bruner

    ASTRONOMY has changed a lot in the days since you had to go and sit for hours with your eyeball at the focal point of a 5-metre-diameter telescope atop a mountain.

    This is quickly evident in How Do You Find an Exoplanet? by John Asher Johnson, formerly a leading researcher at NASA. In 2012, his team discovered three exoplanets orbiting a red dwarf, including the smallest found to date. Now a professor at Harvard University, Johnson’s enthusiasm for his vibrant field is palpable in this valuable, concise guide for amateur astronomers and anyone else not afraid of a few technicalities.

    Today, telescopes are controlled from a computer in a heated room. We have also lived through a revolution in our understanding of the cosmos. At the time of writing, we have discovered 2042 worlds orbiting other stars. This is one of the hottest areas in current research, with new finds making headlines almost weekly.

    Since these remote planets are vanishingly dim alongside the overwhelming glare of their host stars, how do we find them? Johnson rattles through the astronomers’ main tricks. The two most successful techniques involve measuring the radial velocity, or wobble, of a star as it is tugged by an orbiting planet, and registering the minuscule dimming of starlight as a planet transits across the face of a star.

    We are also getting good at capturing images of exoplanets alongside their stars. And then there is microlensing, where an exoplanet is detected by the way its gravity focuses the light of a distant background star. [Albert] Einstein’s general theory of relativity predicts this effect, but attempts to apply it to astronomy were abandoned in 1936 because of the limits of photographic plate technology at the time.

    The greatest value of reading an “insider” book, though, is the insight the author can give us into what we can expect in the near future. For my money, the most exciting discoveries will come from ESPRESSO – a particularly apt acronym for this nocturnal profession – which stands for Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations.

    ESO Espresso
    Espresso in the clean room

    This ultra-high-resolution spectrometer will soon be installed in the [ESO] Very Large Telescope in northern Chile, where it will simultaneously harness the light-gathering capabilities of four huge 8.2- metre telescopes. By measuring the wobble of a targeted star down to a velocity of just 10 centimetres per second, ESPRESSO will be able to detect Earth-like planets in the habitable zone of their star.

    As those headlines about new exoplanets increase, after reading this book, you will be able to say you predicted as much.

    How Do You Find an Exoplanet?
    John Asher Johnson
    Princeton University Press

    See the full article here .

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  • richardmitnick 9:48 am on January 17, 2016 Permalink | Reply
    Tags: , , , Exoplanets   

    From ESO: ESOCast 79 – 20 Years of Exoplanets 


    European Southern Observatory

    Published on Dec 8, 2015

    Not a single confirmed planet outside the Solar System had been detected before the year 1990. But, remarkably, we now know of thousands and have studied many in surprising detail. This ESOcast takes a look at how ESO’s observatories in Chile have been at the forefront of this enormous expansion in knowledge, and how their state-of-the-art instruments are continuing to discover and study the extraordinary diversity of exoplanets.

    Watch, enjoy, learn.

    See the full article here .

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO NTT
    NTT

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
  • richardmitnick 9:49 am on January 15, 2016 Permalink | Reply
    Tags: , , , Exoplanets   

    From Daily Galaxy: “”Nixing 100 Billion Galaxies” –Bayesian Reasoning Dismisses Existence of Alien Life” 

    Daily Galaxy
    The Daily Galaxy

    January 14, 2016
    No writer credit found

    Temp 1
    Image credits: NASA/ESA/IAC/HFF Team, STScI

    Carl Sagan said that “extraordinary claims, require extraordinary evidence.” In a stunning display of mathematical logic, David Spiegel of Princeton University and Edwin Turner from the University of Tokyo published a paper in 2012 that turns the Drake equation upside down using Bayesian reasoning to show that just because we evolved on Earth, doesn’t mean that the same occurrence would necessarily happen elsewhere; “using evidence of our own existence doesn’t show anything” they argue, “other than that we are here.”
    The recent Kepler Space-Telescope discoveries of planets similar to Earth in size and proximity to the planets’ respective suns have sparked scientific and public excitement about the possibility of also finding Earth-like life on those worlds.

    NASA Kepler Telescope
    NASA/Kepler

    But the Princeton University researchers have found that the expectation that life — from bacteria to sentient beings — has or will develop on other planets as on Earth might be based more on optimism than scientific evidence.

    Astrophysical sciences professor Turner and lead author Spiegel analyzed what is known about the likelihood of life on other planets in an effort to separate the facts from the mere expectation that life exists outside of Earth. The researchers used a Bayesian analysis — which weighs how much of a scientific conclusion stems from actual data and how much comes from the prior assumptions of the scientist — to determine the probability of extraterrestrial life once the influence of these presumptions is minimized.

    Turner and Spiegel, who is now at the Institute for Advanced Study, argued in the Proceedings of the National Academy of Sciences [no link to paper] that the idea that life has or could arise in an Earth-like environment has only a small amount of supporting evidence, most of it extrapolated from what is known about abiogenesis, or the emergence of life, on early Earth. Instead, their analysis showed that the expectations of life cropping up on exoplanets — those found outside Earth’s solar system — are largely based on the assumption that it would or will happen under the same conditions that allowed life to flourish on this planet.

    In fact, the researchers conclude, the current knowledge about life on other planets suggests that it’s very possible that Earth is a cosmic aberration where life took shape unusually fast. If so, then the chances of the average terrestrial planet hosting life would be low.

    “Fossil evidence suggests that life began very early in Earth’s history and that has led people to determine that life might be quite common in the universe because it happened so quickly here, but the knowledge about life on Earth simply doesn’t reveal much about the actual probability of life on other planets,” Turner said.

    “Information about that probability comes largely from the assumptions scientists have going in, and some of the most optimistic conclusions have been based almost entirely on those assumptions,” he said.

    Turner and Spiegel used Bayes’ theorem to assign a sliding mathematical weight to the prior assumption that life exists on other planets. The “value” of that assumption was used to determine the probability of abiogenesis, in this case defined as the average number of times that life arises every billion years on an Earth-like planet. Turner and Spiegel found that as the influence of the assumption increased, the perceived likelihood of life existing also rose, even as the basic scientific data remained the same.

    “If scientists start out assuming that the chances of life existing on another planet as it does on Earth are large, then their results will be presented in a way that supports that likelihood,” Turner said. “Our work is not a judgment, but an analysis of existing data that suggests the debate about the existence of life on other planets is framed largely by the prior assumptions of the participants.”

    Joshua Winn, an associate professor of physics at the Massachusetts Institute of Technology, said that Turner and Spiegel cast convincing doubt on a prominent basis for expecting extraterrestrial life. Winn, who focuses his research on the properties of exoplanets, is familiar with the research but had no role in it.

    “There is a commonly heard argument that life must be common or else it would not have arisen so quickly after the surface of the Earth cooled,” Winn said. “This argument seems persuasive on its face, but Spiegel and Turner have shown it doesn’t stand up to a rigorous statistical examination — with a sample of only one life-bearing planet, one cannot even get a ballpark estimate of the abundance of life in the universe.

    “I also have thought that the relatively early emergence of life on Earth gave reasons to be optimistic about the search for life elsewhere,” Winn said. “Now I’m not so sure, though I think scientists should still search for life on other planets to the extent we can.”

    Deep-space satellites and telescope projects have recently identified various planets that resemble Earth in their size and composition, and are within their star’s habitable zone, the optimal distance for having liquid water.

    Of particular excitement have been the discoveries of NASA’s Kepler Space Telescope. In December 2011, NASA announced the first observation of Kepler-22b, a planet 600 light years from Earth and the first found within the habitable zone of a Sun-like star.

    Temp 3
    Kepler-22b — Comfortably Circling within the Habitable Zone.This diagram compares our solar system to Kepler-22, a star system containing the first “habitable zone” planet discovered by NASA’s Kepler mission. The habitable zone is the spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth.

    Kepler-22’s star is a bit smaller than our sun, so its habitable zone is slightly closer in. The diagram shows an artist’s rendering of the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. Kepler-22b has a yearly orbit of 289 days. The planet is the smallest known to orbit in the middle of the habitable zone of a sun-like star. It’s about 2.4 times the size of Earth.
    Image credit: NASA/Ames/JPL-Caltech
    Date 5 December 2011

    Weeks later, NASA reported Keplers-20e and -20f, the first Earth-sized planets found orbiting a Sun-like star. NASA has since announced the discovery of over 2000 Kepler planets, with some 500 possible Earth-like candidates.

    While these observations tend to stoke the expectation of finding Earth-like life, they do not actually provide evidence that it does or does not exist, Spiegel explained. Instead, these planets have our knowledge of life on Earth projected onto them, he said.

    Yet, when what is known about life on Earth is taken away, there is no accurate sense of how probable abiogenesis is on any given planet, Spiegel said. It was this “prior ignorance,” or lack of expectations, that he and Turner wanted to account for in their analysis, he said.

    “When we use a mathematical prior that truly represents prior ignorance, the data of early life on Earth becomes ambiguous,” Spiegel said.

    “Our analysis suggests that abiogenesis could be a rather rapid and probable process for other worlds, but it also cannot rule out at high confidence that abiogenesis is a rare, improbable event,” Spiegel said. “We really have no idea, even to within orders of magnitude, how probable abiogenesis is, and we show that no evidence exists to substantially change that.”

    Spiegel and Turner also propose that once this planet’s history is considered, the emergence of life on Earth might be so distinct that it is a poor barometer of how it occurred elsewhere, regardless of the likelihood that such life exists.

    In a philosophical turn, they suggest that because humans are the ones wondering about the emergence of life, it is possible that we must be on a planet where life began early in order to reach a point so soon after the planet’s formation 4.5 billion years ago where we could wonder about it.

    Thus, Spiegel and Turner explored how the probability of exoplanetary abiogenesis would change if it turns out that evolution requires, as it did on Earth, roughly 3.5 billion years for life to develop from its most basic form to complex organisms capable of pondering existence. If that were the case, then the 4.5 billion-year-old Earth clearly had a head start. A planet of similar age where life did not begin until several billion years after the planet formed would have only basic life forms at this point.

    “Dinosaurs and horseshoe crabs, which were around 200 million years ago, presumably did not consider the probability of abiogenesis. So, we would have to find ourselves on a planet with early abiogenesis to reach this point, irrespective of how probable this process actually is,” Spiegel said. “This evolutionary timescale limits our ability to make strong inferences about how probable abiogenesis is.”

    Turner added, “It could easily be that life came about on Earth one way, but came about on other planets in other ways, if it came about at all. The best way to find out, of course, is to look. But I don’t think we’ll know by debating the process of how life came about on Earth.”

    Again, said Winn of MIT, Spiegel and Turner offer a unique consideration for scientists exploring the possibility of life outside of Earth.

    “I had never thought about the subtlety that we as a species could never have ‘found’ ourselves on a planet with a late emergence of life if evolution takes a long time to produce sentience, as it probably does,” Winn said.

    “With that in mind,” he said, “it seems reasonable to say that scientists cannot draw any strong conclusion about life on other planets based on the early emergence of life on Earth.”

    What Bayesian reasoning overlooks, of course, is the inconvenient fact that there are some one trillion galaxies in the known universe and some 50 billion planets estimated to exist in the Milky Way alone and some 500,000,000 predicted to exist in a habitable zone. Spiegel and Turner point out that basing our expectations of life existing on other planets, for no better reason that it exists here, is really only proof that were are more than capable of deceiving ourselves into thinking that things are much more likely than they really are.

    NASA’s Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies shown below that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed “Pandora’s Cluster,” also known as Abell 2744. The Hubble team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster’s brightness.

    Temp 2
    No image credit found

    NASA Hubble Telescope
    NASA/ESA Hubble

    They argue that other unknown factors exist that could have contributed to us being here that we don’t yet understand. So, they conclude that, deriving numbers from an equation such as that put forth by Drake, only serves to underscore our belief in the existence of other alien life forms, rather than the actual chances of it being so.

    We think evidence will be discovered in the next 20 years: The Kepler mission has discovered 1,235 exoplanets that revolve around a sun, in an area that represents around 1/400th of the Milky Way. By extrapolating these numbers, the Kepler team has estimated that there are at least 50 billion exoplanets in our galaxy — 500 million of which sit inside the habitable “Goldilocks” zones of their suns, the area that it is neither too hot nor too cold to support life.

    Astronomers estimate that there are 100 billion galaxies in the universe. If you want to extrapolate those numbers, that means there are around 50,000,000,000,000,000,000 (50 quintillion) potentially habitable planets in the universe.

    As Arthur C. Clarke, physicist and author of 2001: A Space Odyssey wrote, “The idea that we are the only intelligent creatures in a cosmos of a hundred billion galaxies is so preposterous that there are very few astronomers today who would take it seriously. It is safest to assume therefore, that they are out there and to consider the manner in which this may impinge upon human society.”To an objectivist, empirical view, the rules of Bayesian statistics can be justified by requirements of rationality and consistency and interpreted as an extension of logic. Using a subjectivist view, however, the state of knowledge measures a “personal belief”.

    More information: “Life might be rare despite its early emergence on Earth: a Bayesian analysis of the probability of abiogenesis” http://arxiv.org/abs/1107.3835 and physorg.com

    The Daily Galaxy via Princeton University

    Image credit: Image credit: NASA/ESA/IAC/HFF Team, STScI

    See the full article here .

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  • richardmitnick 11:15 pm on January 14, 2016 Permalink | Reply
    Tags: , , Exoplanets, ,   

    From Ethan Siegel: “Kepler found its longest-period exoplanet ever” 

    Starts with a bang
    Starts with a Bang

    1.14.16
    Ethan Siegel

    Temp 1
    Image credit: NASA / Michele Johnson.

    And it didn’t even need a transit to do it!

    “Mars is much closer to the characteristics of Earth. It has a fall, winter, summer and spring. North Pole, South Pole, mountains and lots of ice. No one is going to live on Venus; no one is going to live on Jupiter.”
    -Buzz Aldrin

    The Kepler spacecraft was one of the most brilliant technical and scientific achievements of the 2010s.

    NASA Kepler Telescope
    NASA/Kepler

    By launching a telescope into space and pointing it at the same field-of-view of stars for years and years, collecting the light from each one continuously, it became sensitive to tiny, minuscule variations in the intensity of their starlight.

    2
    Image credit: Painting by Jon Lomberg, Kepler mission diagram added by NASA.

    There are a number of reasons the amount of light a star emits could vary in intensity: it could be an intrinsically variable star (like a Cepheid, RR Lyrae or Delta Scuti variable, among others), it could be an eclipsing binary star system (an example of an extrinsic variable star), where one star periodically slips behind the other, or it could be due to the most exciting reason of all: something is transiting in front of that star to block a fraction of its light.

    3
    Image credit: NASA Ames.

    Sometimes, the transiting object could be close by, like an asteroid or a Kuiper belt object.

    4
    Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.)

    Other times, it could be more distant, like an interstellar object. But what Kepler’s built to look for, and what it’s particularly seeking, is planets around the stars it’s looking at. In order for this method to be successful, you need for a number of things to happen all at once:

    You need the planetary orbit to be so serendipitously aligned with the star and your spacecraft that the orbital path appears to transit across the disk of the star from your point of view.

    You need the ratio of the planet’s size to the star’s to be large enough that your spacecraft can measure the transit’s magnitude.
    And you need the planet to transit across the star’s surface more than once so that you can be sure it wasn’t a foreground object having nothing to do with the star system you’re observing.

    Even if every star out there had a Solar System like our own, all three of these things being true would be a relatively rare occurrence, so if you’re just searching blindly, you need lots of targets. Kepler began operation in late 2009, pointing at an area of the Milky Way containing about 150,000 stars it was sensitive to. It measured the light from those stars over a long period of time — years — and to date has found close to 10,000 planetary candidates using these criteria. Some of them turn out not to be planets after all, as lots of things can mimic a planetary signal.

    This is why, if you want to confirm an exoplanet candidate, you need a second, independent method to do so.

    5
    Image credit: ESO, under the Creative Commons Attribution 4.0 International License.

    Normally, we use the stellar wobble method. Every planet that orbits a star has a mass, and just as the star pulls the planet into an elliptical orbit around it, the planet adds a tiny elliptical motion to the star’s orbit as well. This doesn’t produce a perceptible change in the star’s position, but does produce a perceptible change in the wavelength of the light emitted from the star: a redshift or blueshift, as the star moves either away or towards you in its periodic dance.

    Over a thousand planetary systems discovered by Kepler have been confirmed by the stellar wobble method, including Kepler-56, which is a star that’s presently evolving into a red giant as its core runs out of hydrogen to burn. Two large, inner planets — one about the mass of Neptune and one about half the mass of Jupiter — were found around this system. The large masses and close-in orbits make these exactly the types of planets that Kepler can find most easily, and also the types of planets that can easily and quickly be confirmed via stellar wobble.

    6
    Image credit: NASA Ames/W. Stenzel, of the Kepler planetary candidates as of July 2015.

    Kepler’s no good at finding planets that are much farther out than Earth is from our Sun, since in order to build up a robust, quality signal, you need multiple transits (more is better) of the planet across the star, which is very hard to do for a planet like say, Jupiter in our Solar System, which has an orbital period of 12 years, especially if your spacecraft has only been up there since 2009. To make things even worse, your chances of having a good alignment with a planet that’s more distant from its parent star drops very quickly as you move away. There’s a reason that hot, inner worlds are so abundant with Kepler: they’re the easiest ones to find.

    But sometimes, you do your follow-up for the transiting planets (the ones Kepler easily finds), and when you look for the stellar wobble, you not only find it…

    7
    Image credit: D. Huber et al., Science 18 October 2013: Vol. 342 no. 6156 pp. 331–334; DOI: 10.1126/science.1242066.

    but you find something else. In the case of Kepler-56, the innermost planet (blue line) gives off a clear signal that can be teased out; the second large planet (red line, higher mass) gives off an even more prominent signal. Yet perhaps the most notable signal is just labeled “trend,” which you need to add to the two planetary signals to get the observed data. When this was first reported in 2013, it was assumed this was probably a planet, but more data was needed to know its orbital properties: mass and period. As first released this week at the American Astronomical Society’s annual meeting, Kepler-56 appears to have a third planet orbiting it — about six times the mass of Jupiter with a period of around three Earth-years — thanks to the work of Justin Otor, Benjamin Montet and John A. Johnson.

    8
    Image credit: Danny Barringer, of Justin Otor’s poster at AAS 227.

    Finally, one almost complete “wobble cycle” of the outer planet has been observed with the follow-up data, and it’s actually a planet that doesn’t transit the star from our line-of-sight. It turns out that Kepler really can’t find these outer worlds on its own, but the clues that Kepler provides, of where to look for planetary systems where the stellar wobble can teach you so much more, can lead us to discover massive, outer planets that we never would’ve known to look for otherwise. Where there’s smoke, you look for the fire; where there are inner worlds, look for the outer ones. If you see the steep rise or fall associated with a massive wobble, you just might break the record.

    This article was partially based on information obtained during the 227th American Astronomical Society meeting, some of which may be unpublished.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 3:53 pm on December 1, 2015 Permalink | Reply
    Tags: , , Exoplanets,   

    From Berkeley: “Exoplanet kicked into exile” 

    UC Berkeley

    UC Berkeley

    December 01, 2015
    Robert Sanders

    A planet discovered last year sitting at an unusually large distance from its star – 16 times farther than Pluto is from the sun – may have been kicked out of its birthplace close to the star in a process similar to what may have happened early in our own solar system’s history.

    1
    A wide-angle view of the star HD 106906 taken by the Hubble Space Telescope and a close-up view from the Gemini Planet Imager reveal a dynamically disturbed system of comets, suggesting a link between this and the unusually distant planet (upper right), 11 times the mass of Jupiter. Click image for hi-res versions & caption. Paul Kalas image, UC Berkeley.

    Images from the Gemini Planet Imager (GPI) in the Chilean Andes and the Hubble Space Telescope show that the star has a lopsided comet belt indicative of a very disturbed solar system, and hinting that the planet interactions that roiled the comets closer to the star might have sent the exoplanet into exile as well.

    NASA Hubble Telescope
    NASA/ESA Hubble

    The planet may even have its own ring of debris that it dragged along with it.

    “We think that the planet itself could have captured material from the comet belt, and that the planet is surrounded by a large dust ring or dust shroud,” said Paul Kalas, an adjunct professor of astronomy at the University of California, Berkeley. “We conducted three tests and found tentative evidence for a dust cloud, but the jury is still out.”

    “The measurements we made on the planet suggest it may be dustier than comparison objects, and we are making follow-up observations to check if the planet is really encircled by a disk – an exciting possibility,” added Abhi Rajan, a graduate student at Arizona State University who analyzed the planet images.

    Such planets are of interest because in its youth, our own solar system may have had planets that were kicked out of the local neighborhood and are no longer among of the eight planets we see today.

    “Is this a picture of our solar system when it was 13 million years old?” asks Kalas. “We know that our own belt of comets, the Kuiper belt, lost a large fraction of its mass as it evolved, but we don’t have a time machine to go back and see how it was decimated.

    3
    Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.

    One of the ways, though, is to study these violent episodes of gravitational disturbance around other young stars that kick out many objects, including planets.”

    The disturbance could have been caused by a passing star that perturbed the inner planets, or a second massive planet in the system. The GPI team looked for another large planet closer to the star that may have interacted with the exoplanet, but found nothing outside of a Uranus-sized orbit.

    Kalas and Rajan will discuss the observations during a Google+ Hangout On Air at 7 a.m. Hawaii time (noon EST) on Dec. 1 during Extreme Solar Systems III, the third in a series of international meetings on exoplanets that this year takes place on the 20th anniversary of the discovery of the first exoplanet in 1995. Viewers without Google+ accounts may participate via YouTube.

    A paper about the results, with Kalas as lead author, was published in the The Astrophysical Journal on Nov. 20, 2015.

    Young, 13-million-year-old star

    The star, HD 106906, is located 300 light years away in the direction of the constellation Crux and is similar to the sun, but much younger: about 13 million years old, compared to our sun’s 4.5 billion years. Planets are thought to form early in a star’s history, however, and in 2014 a team led by Vanessa Bailey at the University of Arizona discovered a planet HD 106906 b around the star weighing a hefty 11 times Jupiter’s mass and located in the star’s distant suburbs, an astounding 650 AU from the star (one AU is the average distance between Earth and the sun, or 93 million miles).

    3
    The star HD 106906 and the planet HD 106906 b, with Neptune’s orbit for comparison

    3
    The Gemini Planet Imager mounted on the Gemini South telescope in Chile. Courtesy of Gemini Telescopes.

    Planets were not thought to form so far from their star and its surrounding protoplanetary disk, so some suggested that the planet formed much like a star, by condensing from its own swirling cloud of gas and dust. The GPI and Hubble discovery of a lopsided comet belt and possible ring around the planet points instead to a normal formation within the debris disk around the star, but a violent episode that forced it into a more distant orbit.

    Kalas and a multi-institutional team using GPI first targeted the star in search of other planets in May 2015 and discovered that it was surrounded by a ring of dusty material very close to the size of our own solar system’s Kuiper Belt. The emptiness of the central region – an area about 50 AU in radius, slightly larger than the region occupied by planets in our solar system – indicates that a planetary system has formed there, Kalas said.

    He immediately reanalyzed existing images of the star taken earlier by the Hubble Space Telescope and discovered that the ring of dusty material extended much farther away and was extremely lopsided. On the side facing the planet, the dusty material was vertically thin and spanned nearly the huge distance to the known planet, but on the opposite side the dusty material was vertically thick and truncated.

    “These discoveries suggest that the entire planetary system has been recently jostled by an unknown perturbation to its current asymmetric state,” he said. The planet is also unusual in that its orbit is possibly tilted 21 degrees away from the plane of the inner planetary system, whereas most planets typically lie close to a common plane.

    Kalas and collaborators hypothesized that the planet may have originated from a position closer to the comet belt, and may have captured dusty material that still orbits the planet. To test the hypothesis, they carefully analyzed the GPI and Hubble observations, revealing three properties about the planet consistent with a large dusty ring or shroud surrounding it. However, for each of the three properties, alternate explanations are possible.

    The investigators will be pursuing more sensitive observations with the Hubble Space Telescope to determine if HD 106906b is in fact one of the first exoplanets that resembles Saturn and its ring system.

    The inner belt of dust around the star has been confirmed by an independent team using the planet-finding instrument SPHERE on the ESO’s Very Large Telescope in Chile. The lopsided nature of the debris disk was not evident, however, until Kalas called up archival images from Hubble’s Advanced Camera for Surveys.

    The GPI Exoplanet Survey, operated by a team of astronomers at UC Berkeley and 23 other institutions, is targeting 600 young stars, all less than approximately 100 million years old, to understand how planetary systems evolve over time and what planetary dynamics could shape the final arrangement of planets like we see in our solar system today. GPI operates on the Gemini South telescope and provides extremely high-resolution, high-contrast direct imaging, integral field spectroscopy and polarimetry of exoplanets.

    Gemini South telescope
    Gemini South

    Among Kalas’s coauthors are UC Berkeley graduate student Jason Wang. The research was supported by the National Science Foundation and NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate.

    NASA NExSS bloc

    See the full article here .

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