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  • richardmitnick 11:20 am on July 19, 2017 Permalink | Reply
    Tags: , , , , Planet Nine,   

    From Science Alert: “We Now Have More Evidence For The Existence of Planet Nine…” 

    ScienceAlert

    Science Alert

    1
    Artist’s rendering of a Jupiter-sized lonely planet. NASA/JPL

    18 JUL 2017
    MATT WILLIAMS

    …And maybe even Planet Ten?

    In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System.

    Known as “Planet 9”, this hypothetical body was estimated to be about 10 times as massive as Earth and to orbit that our Sun at an average distance of 700 AU. Since that time, multiple studies have been produced that either support or cast doubt on the existence of Planet 9.

    While some argue that the orbits of certain Trans-Neptunian Objects (TNOs) are proof of Planet 9, others argue that these studies suffer from an observational bias.

    The latest study [MNRAS], which comes from a pair of astronomers from the Complutense University of Madrid (UCM), offers a fresh perspective that could settle the debate.

    Using a new technique that focuses on extreme TNOs (ETNOs), they believe the case for Planet 9 can be made.

    Extreme Trans-Neptunian Objects are those that orbit our Sun at average distances greater than 150 AU, and therefore never cross Neptune’s orbit.

    As the UMC team indicate in their study [see above], which was recently published in the Monthly Notices of the Royal Astronomical Society, the distances between the ETNOs nodes and the Sun may point the way towards Planet 9.

    These nodes are the two points at which the orbit of a celestial body crosses the plane of the Solar System. It is at these points that the chances of interacting with other bodies in the Solar System is the greatest, and hence where ETNOs are most likely to experience a drastic change in their orbits (or a collision).

    By measuring where these nodes are, the team believed they could tell if the ETNOs are being perturbed by another object in the area.

    As Carlos de la Fuente Marcos, one of the authors on the study, explained in an interview with The Information and Scientific News Service (SINC):

    “If there is nothing to perturb them, the nodes of these extreme trans-Neptunian objects should be uniformly distributed, as there is nothing for them to avoid, but if there are one or more perturbers, two situations may arise.

    One possibility is that the ETNOs are stable, and in this case they would tend to have their nodes away from the path of possible perturbers, he adds, but if they are unstable they would behave as the comets that interact with Jupiter do, that is tending to have one of the nodes close to the orbit of the hypothetical perturber”.

    For the sake of their research, Doctors Carlos and Raul de la Fuente Marcos conducted calculations and data mining to analyse the nodes of 28 ETNOs and 24 extreme Centaurs (which also orbit the Sun at average distances of more than 150 AUs).

    What they noticed was that these two populations became clustered at certain distances from the Sun, and also noted a correlation between the positions of the nodes and the inclination of the objects.

    This latter find was especially unexpected, and led them to conclude that the orbits of these populations were being affected by the presence of another body – much in the same way that the orbits of comets within our Solar System have been found to be affected by the way they interact with Jupiter.

    As De la Fuente Marcos emphasised:

    “Assuming that the ETNOs are dynamically similar to the comets that interact with Jupiter, we interpret these results as signs of the presence of a planet that is actively interacting with them in a range of distances from 300 to 400 AU.

    We believe that what we are seeing here cannot be attributed to the presence of observational bias”.

    As already mentioned, previous studies that have challenged the existence of Planet 9 cited how the study of TNOs have suffered from an observational bias.

    Basically, they have claimed that these studies made systematic errors in how they calculated the orientations in the orbits of TNOs, in large part because they had all been directed towards the same region of the sky.

    By looking at the nodal distances of ETNOs, which depend on the size and shape of their orbits, this most recent study offers the first evidence of Planet 9’s existence that is relatively free of this bias.

    At the moment, only 28 ETNOs are known, but the authors are confident that the discovery of more – and the analysis of their nodes – will confirm their observations and place further constraints on the orbit of Planet 9.

    In addition, the pair of astronomers offered some thoughts on recent work that has suggested the possible existence of a Planet 10.

    While their study does not take into account the existence of a Mars-sized body – which is said to be responsible for an observable “warp” in the Kuiper Belt – they acknowledge that there is compelling evidence that such a planet-sized body exists.

    As de la Fuente Marcos said:

    “Given the current definition of planet, this other mysterious object may not be a true planet, even if it has a size similar to that of the Earth, as it could be surrounded by huge asteroids or dwarf planets.

    In any case, we are convinced that Volk and Malhotra’s work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence”.

    It seems that the outer Solar System is getting more crowded with every passing year.

    And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t.

    If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!

    See the full article here .

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  • richardmitnick 7:17 am on April 2, 2017 Permalink | Reply
    Tags: , , , , Planet Nine   

    From ANU: “ANU leads citizen search for new planet in Solar System” 

    ANU Australian National University Bloc

    Australian National University

    27 March 2017

    1
    U Manchester Professor Brian Cox and ANU astronomer Dr. Brad Tucker. Credit: NASA

    2
    Courtesy Caltech / R. Hurt (IPAC)

    Four Candidates For Planet 9 Located

    ANU is launching a search for a new planet in our Solar System, inviting anyone around the world with access to the Internet to help make the historic discovery.

    A concentrated three-day search for a mysterious, unseen planet in the far reaches of our own solar system has yielded four possible candidates. The search for the so-called Planet 9 was part of a real-time search with a Zooniverse citizen science project, in coordination with the BBC’s Stargazing Live broadcast from the Australian National University’s Siding Spring Observatory.

    Researcher Brad Tucker from ANU, who led the effort, said about 60,000 people from around the world classified over four million objects during the three days, using data from the SkyMapper telescope at Siding Spring.



    ANU Skymapper telescope, a fully automated 1.35 m (4.4 ft) wide-angle optical telescope at Siding Spring Observatory , near Coonabarabran, New South Wales, Australia

    He and his team said that even if none of the four candidates turn out to be the hypothetical Planet 9, the effort was scientifically valuable, helping to verify their search methods as exceptionally viable.

    “We’ve detected minor planets Chiron and Comacina, which demonstrates the approach we’re taking could find Planet 9 if it’s there,” Tucker said. “We’ve managed to rule out a planet about the size of Neptune being in about 90 per cent of the southern sky out to a depth of about 350 times the distance the Earth is from the Sun.

    3
    SAMI, a new multi-object integral field spectrograph at Siding Spring Observatory, which was used to look for the hypothetical Planet 9. Credit: Dilyar Barat via Twitter.

    (Universe Today)

    Anyone who helps find the so-called Planet 9 will work with ANU astronomers to validate the discovery through the International Astronomical Union.

    3
    Researchers from Australian National University pose with BBC astronomers Chris Lintott, Brian Cox and Dara O’Brien. Credit: ANU.

    ANU astrophysicist Dr Brad Tucker is leading the project, which is being launched by Professor Brian Cox during a BBC Stargazing Live broadcast from the ANU Siding Spring Observatory.

    “We have the potential to find a new planet in our Solar System that no human has ever seen in our two-million-year history,” said Dr Tucker from the ANU Research School of Astronomy and Astrophysics.

    Dr Tucker said astronomers had long discussed the likelihood of a ninth planet on the outer edges of the Solar System, but nothing had been found yet.

    “Planet 9 is predicted to be a super Earth, about 10 times the mass and up to four times the size of our planet. It’s going to be cold and far away, and about 800 times the distance between Earth and the sun. It’s pretty mysterious,” he said.

    The ANU project will allow citizen scientists to use a website to search hundreds of thousands of images taken by the ANU SkyMapper telescope at Siding Spring.

    SkyMapper will take 36 images of each part of the southern sky, which is relatively unexplored, and identify changes occurring within the Universe.

    Finding Planet 9 involves citizen volunteers scanning the SkyMapper images online to look for differences, Dr Tucker said.

    “It’s actually not that complicated to find Planet 9. It really is spot the difference. Then you just click on the image, mark what is different and we’ll take care of the rest,” Dr Tucker said.

    He said he expected people to also find and identify other mystery objects in space, including asteroids, comets and dwarf planets like Pluto.

    “If you find an asteroid or dwarf planet, you can’t actually name it after yourself,” Dr Tucker said.

    “But you could name it after your wife, brother or sister. We need to follow all of the rules set by the International Astronomical Union.”

    Dr Tucker said modern computers could not match the passion of millions of people.

    “It will be through all our dedication that we can find Planet 9 and other things that move in space,” he said.

    Co-researcher and Head of SkyMapper Dr Chris Wolf said SkyMapper was the only telescope in the world that maps the whole southern sky.

    “Whatever is hiding there that you can’t see from the north, we will find it,” Dr Wolf said.

    From 28 to 30 March at 8pm London time, BBC Stargazing Live hosted by Professor Cox and comedian Dara O Briain is expected to be viewed by around five million people.

    The ABC [Australian, not U.S.] will broadcast an Australian Stargazing Live program from Siding Spring from 4 to 6 April, hosted by Professor Cox and Julia Zemiro.

    SkyMapper is a 1.3-metre telescope that is creating a full record of the southern sky for Australian astronomers.

    People can to participate in the ANU citizen science project to search for Planet 9 at http://www.planet9search.org

    See the full article here .

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    ANU Campus

    ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.

    Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.

     
  • richardmitnick 9:59 am on February 23, 2017 Permalink | Reply
    Tags: Extreme trans Neptunian objects (ETNOs), , Planet Nine, The visible spectrum can give some information also about their composition   

    From IAC: “New data about two distant asteroids give a clue to the possible ‘Planet Nine'” 

    IAC

    Instituto de Astrofísica de Canarias – IAC

    Feb. 17, 2017
    Julia de León (IAC):
    jmlc@iac.es
    +39922425717

    1
    No image caption. No image credit
    The dynamical properties of these asteroids, observed spectroscopiccally for the first time using the Gran Telescopio CANARIAS, suggest a possible common origin and give a clue to the existence of a planet beyond Pluto, the so-called “Planet Nine”.

    In the year 2000 the first of a new class of distant solar system objects was discovered, orbiting the Sun at a distance greater than that of Neptune: the “extreme trans Neptunian objects (ETNOs). Their orbits are very far from the Sun compared with that of the Earth. We orbit the Sun at a mean distance of one astronomical unit (1 AU which is 150 million kilometres) but the ETNOs orbit at more than 150 AU. To give an idea of how far away they are, Pluto’s orbit is at around 40 AU and its closest approach to the Sun (perihelion) is at 30 AU. This discovery marked a turning point in Solar System studies, and up to now, a total of 21 ETNOs have been identified.

    Recently, a number of studies have suggested that the dynamical parameters of the ETNOs could be better explained if there were one or more planets with masses several times that of the Earth orbiting the Sun at distances of hundreds of AU. In particular, in 2016 the researchers Brown and Batygin used the orbits of seven ETNOs to predict the existence of a “superearth” orbiting the sun at some 700 AU. This range of masses is termed sub Neptunian. This idea is referred to as the Planet Nine Hypothesis and is one of the current subjects of interest in planetary science. However, because the objects are so far away the light we receive from them is very weak and until now the only one of the 21 trans Neptunian objects observed spectroscopically was Sedna.

    Now, a team of researchers led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the Complutense University of Madrid has taken a step towards the physical characterization of these bodies, and to confirm or refute the hypothesis of Planet Nine by studying them. The scientists have made the first spectroscopic observations of 2004 VN112 and 2013 RF98, both of them particularly interesting dynamically because their orbits are almost identical and the poles of the orbits are separated by a very small angle. This suggest a common origin, and their present-day orbits could be the result of a past interaction with the hypothetical Planet Nine. This study, recently published in Monthly Notices of the Royal Astronomical Society, suggests that this pair of ETNOs was a binary asteroid which separated after an encounter with a planet beyond the orbit of Pluto.

    To reach these conclusions, they made the first spectroscopic observations of 2004 VN112 and 2013 RF98 in the visible range. These were performed in collaboration with the support astronomers Gianluca Lombardi and Ricardo Scarpa, using the OSIRIS spectrograph on the Gran Telescopio CANARIAS (GTC), situated in the Roque de los Muchachos Observatory (Garafía, La Plama). It was hard work to identify these asteroids because their great distance means that their apparent movement on the sky is very slow. Then, they measured their apparent magnitudes (their brightness as seen from Earth) and also recalculated the orbit of 2013 RF98, which had been poorly determined. They found this object at a distance of more than an arcminute away from the position predicted from the ephemerides. These observations have helped to improve the computed orbit, and have been published by the Minor Planet Center (MPEC 2016-U18: 2013 RF98), the organism responsible for the identification of comets and minor planets (asteroids) as well as for measurements of their parameters and orbital positions.

    The visible spectrum can give some information also about their composition. By measuring the slope of the spectrum, can be determined whether they have pure ices on their surfaces, as is the case for Pluto, as well as highly processed carbon compounds. The spectrum can also indicate the possible presence of amorphous silicates, as in the Trojan asteroids associated with Jupiter. The values obtained for 2004 VN112 and 2013 RF98 are almost identical and similar to those observed photometrically for two other ETNOs, 2000 CR105 and 2012 VP113. Sedna, however, the only one of these objects which had been previously observed spectroscopically, shows very different values from the others. These five objects are part of the group of seven used to test the hypothesis of Planet Nine, which suggests that all of them should have a common origin, except for Sedna, which is thought to have come from the inner part of the Oort cloud.

    “The similar spectral gradients observed for the pair 2004 VN112 – 2013 RF98 suggests a common physical origin”, explains Julia de León, the first author of the paper, an astrophysicist at the IAC. “We are proposing the possibility that they were previously a binary asteroid which became unbound during an encounter with a more massive object”. To validate this hypothesis, the team performed thousands of numerical simulations to see how the poles of the orbits would separate as time went on. The results of these simulations suggest that a possible Planet Nine, with a mass of between 10 and 20 Earth masses orbiting the Sun at a distance between 300 and 600 AU could have deviated the pair 2004 VN112 – 2013 RF98 around 5 and 10 million years ago. This could explain, in principle, how these two asteroids, starting as a pair orbiting one another, became gradually separated in their orbits because they made an approach to a much more massive object at a particular moment in time.

    Article: Visible spectra of (474640) 2004 VN112 – 2013 RF98 with OSIRIS at the 10.4m GTC: evidence for binary dissociation near aphelion among the extreme trans-Neptunian objects, by Julia de León, Carlos de la Fuente Marcos and Raúl de la Fuente Marcos. Published in Monthly Notices of the Royal Astronomical Society. DOI: https://doi.org/10.1093/mnrasl/slx003

    See the full article here.

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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teachingand outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

    Gran Telescopio  Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain
    Gran Telescopio CANARIAS, GTC

     
  • richardmitnick 8:43 am on February 16, 2017 Permalink | Reply
    Tags: , , Planet Nine,   

    From UC Berkeley: “UC Berkeley, NASA looking for citizen scientists to help find Planet 9” 

    UC Berkeley

    UC Berkeley

    February 15, 2017
    Robert Sanders
    rlsanders@berkeley.edu

    1
    A previously cataloged brown dwarf named WISE 0855−0714 shows up as a moving
    orange dot (upper left) in this loop of WISE images spanning five years. By viewing
    movies like this, anyone can help discover more brown dwarfs or even a 9th planet. (NASA/WISE images)

    Elusive planets and dim failed stars may be lurking around the edges of our solar system, and astronomers from NASA and UC Berkeley want the public’s help to hunt them down.

    Through a new website called Backyard Worlds: Planet 9, anyone can now help search for objects far beyond the orbit of our farthest planet, Neptune, by viewing brief “flipbook” movies made from images captured by NASA’s Wide-field Infrared Survey Explorer (WISE) mission. A faint spot seen moving through background stars might be a new and distant planet orbiting the sun or a nearby brown dwarf.

    NASA/WISE Telescope
    NASA/WISE Telescope

    WISE’s infrared images cover the entire sky about six times over. This has allowed astronomers to search the images for faint, glowing objects that change position over time, which means they are relatively close to Earth. Objects that produce their own faint infrared glow would have to be large, Neptune-size planets or brown dwarfs, which are slightly smaller than stars.

    UC Berkeley postdoctoral researcher Aaron Meisner, a physicist who specializes in analyzing WISE images, has automated the search using computers, but he jumped at the idea by NASA astronomer Marc Kuchner to ask the public to eyeball the millions of WISE images. NASA and its collaborators, including UC Berkeley, are launching the planet and brown dwarf search Feb. 15.

    “Automated searches don’t work well in some regions of the sky, like the plane of the Milky Way galaxy, because there are too many stars, which confuses the search algorithm,” said Meisner, who last month published the results of an automated survey of 5 percent of the WISE data, which revealed no new objects. Online volunteers “using the powerful ability of the human brain to recognize motion” may be luckier, he said.

    “Backyard Worlds: Planet 9 has the potential to unlock once-in-a-century discoveries, and it’s exciting to think they could be spotted first by a citizen scientist,” he added.

    “There are just over four light-years between Neptune, the farthest known planet in our solar system, and Proxima Centauri, the nearest star, and much of this vast territory is unexplored,” said Kuchner, the lead researcher and an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    “Because there’s so little sunlight, even large objects in that region barely shine in visible light. But by looking in the infrared, WISE may have imaged objects we otherwise would have missed.”

    Planet 9

    People have long theorized about unknown planets far beyond Neptune and the dwarf planet Pluto, but until recently there was no evidence to support the idea. Last year, however, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of an as-yet-unseen ninth planet in the solar system’s outer reaches. This “Planet 9” would be similar in size to Neptune, but up to a thousand times farther from the sun than Earth, and would orbit the sun perhaps once every 15,000 years. It would be so faint as to have so far evaded discovery.


    Video courtesy of the American Museum of Natural History.

    At the moment, the existence of Planet 9 is still under debate. Meisner thinks it’s more likely that volunteers will find brown dwarfs in the solar neighborhood. While Planet 9 would look very blue in WISE time-lapse animations, brown dwarfs would look very red and move across the sky more slowly.

    WISE images have already turned up hundreds of previously unknown brown dwarfs, including the sun’s third- and fourth-closest known neighbors. He hopes that the Backyard Worlds search will turn up a new nearest neighbor to our sun.

    “We’ve pre-processed the WISE data we’re presenting to citizen scientists in such a way that even the faintest moving objects can be detected, giving us an advantage over all previous searches,” Meisner said. Moving objects flagged by participants will be prioritized by the science team for later follow-up observations by professional astronomers. Participants will share credit for their discoveries in any scientific publications that result from the project.

    2
    A very blue Neptune-like planet, dubbed Planet 9, may be lurking dozens of times further from the sun than Pluto, as depicted in this artist’s rendering. Citizen scientists who join the Backyard Worlds: Planet 9 project may be the first to spot it. (NASA image)

    WISE and NEOWISE

    The WISE telescope scanned the entire sky between 2010 and 2011, producing the most comprehensive survey at mid-infrared wavelengths currently available. With the completion of its primary mission, WISE was shut down in 2011, then reactivated in 2013 and given a new mission: assisting NASA’s efforts to identify potentially hazardous near-Earth objects, which are asteroids and comets in the vicinity of our planet. The mission was renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE).

    The new website uses all of the WISE and NEOWISE data to search for unknown objects in and beyond our own solar system, including the putative Planet 9. If Planet 9 exists and is as bright as some predict, it could show up in WISE data.

    Meisner said WISE is uniquely suited for discovering extremely cold brown dwarfs, which can be invisible to the biggest ground-based telescopes despite being very close.

    “Brown dwarfs form like stars but evolve like planets, and the coldest ones are much like Jupiter,” said team member Jackie Faherty, an astronomer at the American Museum of Natural History in New York. “By using Backyard Worlds: Planet 9, the public can help us discover more of these strange rogue worlds.”

    Backyard Worlds: Planet 9 is a collaboration between NASA, UC Berkeley, the American Museum of Natural History in New York, Arizona State University, the Space Telescope Science Institute in Baltimore and Zooniverse, a collaboration of scientists, software developers and educators that collectively develops and manages citizen-science projects on the internet. Zooniverse will spread the word among its many citizen volunteers

    NASA’s Jet Propulsion Laboratory in Pasadena, California, manages and operates WISE, part of NASA’s Explorers Program.

    Meisner, who specializes in creating high-resolution maps of the universe, is also currently working on the Dark Energy Spectroscopic Instrument, a project at Lawrence Berkeley National laboratory that seeks to learn how mysterious dark energy affects the expansion of the universe.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018
    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

    Follow Backyard Worlds: Planet 9 on Facebook or Twitter, @backyardworlds.

    RELATED INFORMATION

    Backyard Worlds: Planet 9 Zooniverse Project
    Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images
    FindPlanetNine Blog [link did not work]

    See the full article here .

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  • richardmitnick 3:59 pm on October 19, 2016 Permalink | Reply
    Tags: , Curious Tilt of the Sun Traced to Undiscovered Planet, Planet Nine   

    From Caltech: “Curious Tilt of the Sun Traced to Undiscovered Planet” 

    Caltech Logo
    Caltech

    10/19/2016

    Robert Perkins
    (626) 395-1862
    rperkins@caltech.edu

    1
    This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Credit: Caltech/R. Hurt (IPAC).

    Planet Nine—the undiscovered planet at the edge of the Solar System that was predicted by the work of Caltech’s Konstantin Batygin and Mike Brown in January 2016—appears to be responsible for the unusual tilt of the sun, according to a new study.

    The large and distant planet may be adding a wobble to the solar system, giving the appearance that the sun is tilted slightly.

    “Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar system has no choice but to slowly twist out of alignment,” says Elizabeth Bailey, a graduate student at Caltech and lead author of a study announcing the discovery.

    All of the planets orbit in a flat plane with respect to the sun, roughly within a couple degrees of each other. That plane, however, rotates at a six-degree tilt with respect to the sun—giving the appearance that the sun itself is cocked off at an angle. Until now, no one had found a compelling explanation to produce such an effect. “It’s such a deep-rooted mystery and so difficult to explain that people just don’t talk about it,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.

    Brown and Batygin’s discovery of evidence that the sun is orbited by an as-yet-unseen planet—that is about 10 times the size of Earth with an orbit that is about 20 times farther from the sun on average than Neptune’s—changes the physics. Planet Nine, based on their calculations, appears to orbit at about 30 degrees off from the other planets’ orbital plane—in the process, influencing the orbit of a large population of objects in the Kuiper Belt, which is how Brown and Batygin came to suspect a planet existed there in the first place.

    “It continues to amaze us; every time we look carefully we continue to find that Planet Nine explains something about the solar system that had long been a mystery,” says Batygin, an assistant professor of planetary science.

    Their findings have been accepted for publication in an upcoming issue of the Astrophysical Journal, and will be presented on October 18 at the American Astronomical Society’s Division for Planetary Sciences annual meeting, held in Pasadena.

    The tilt of the solar system’s orbital plane has long befuddled astronomers because of the way the planets formed: as a spinning cloud slowly collapsing first into a disk and then into objects orbiting a central star.

    Planet Nine’s angular momentum is having an outsized impact on the solar system based on its location and size. A planet’s angular momentum equals the mass of an object multiplied by its distance from the sun, and corresponds with the force that the planet exerts on the overall system’s spin. Because the other planets in the solar system all exist along a flat plane, their angular momentum works to keep the whole disk spinning smoothly.

    Planet Nine’s unusual orbit, however, adds a multi-billion-year wobble to that system. Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly, Brown says.

    The next question, then, is how did Planet Nine achieve its unusual orbit? Though that remains to be determined, Batygin suggests that the planet may have been ejected from the neighborhood of the gas giants by Jupiter, or perhaps may have been influenced by the gravitational pull of other stellar bodies in the solar system’s extreme past.

    For now, Brown and Batygin continue to work with colleagues throughout the world to search the night sky for signs of Planet Nine along the path they predicted in January. That search, Brown says, may take three years or more.

    See the full article here .

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    Caltech campus
    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

     
  • richardmitnick 1:18 pm on May 3, 2016 Permalink | Reply
    Tags: , , , Planet Nine   

    From CfA: “Planet Nine: A World That Shouldn’t Exist” 

    Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory

    [This subject is getting old, but this article presents three new papers on the subject.]

    May 3, 2016
    Christine Pulliam
    Media Relations Manager
    Harvard-Smithsonian Center for Astrophysics
    617-495-7463

    1
    Alleged Planet nine. No image credit.

    Planet nine orbit image Credit Caltech R. Hurt (IPAC)
    Planet nine orbit image Credit Caltech R. Hurt (IPAC)

    Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. Since then theorists have puzzled over how this planet could end up in such a distant orbit.

    New research by astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) examines a number of scenarios and finds that most of them have low probabilities. Therefore, the presence of Planet Nine remains a bit of a mystery.

    “The evidence points to Planet Nine existing, but we can’t explain for certain how it was produced,” says CfA astronomer Gongjie Li, lead author on a paper accepted for publication* in the Astrophysical Journal Letters.

    Planet Nine circles our Sun at a distance of about 40 billion to 140 billion miles, or 400 – 1500 astronomical units. (An astronomical unit or A.U. is the average distance of the Earth from the Sun, or 93 million miles.) This places it far beyond all the other planets in our solar system. The question becomes: did it form there, or did it form elsewhere and land in its unusual orbit later?

    Li and her co-author Fred Adams (University of Michigan) conducted millions of computer simulations in order to consider three possibilities. The first and most likely involves a passing star that tugs Planet Nine outward. Such an interaction would not only nudge the planet into a wider orbit but also make that orbit more elliptical. And since the Sun formed in a star cluster with several thousand neighbors, such stellar encounters were more common in the early history of our solar system.

    However, an interloping star is more likely to pull Planet Nine away completely and eject it from the solar system. Li and Adams find only a 10 percent probability, at best, of Planet Nine landing in its current orbit. Moreover, the planet would have had to start at an improbably large distance to begin with.

    CfA astronomer Scott Kenyon believes he may have the solution to that difficulty. In two papers submitted to the Astrophysical Journal, Kenyon and his co-author Benjamin Bromley (University of Utah) use computer simulations to construct plausible scenarios for the formation of Planet Nine in a wide orbit.

    “The simplest solution is for the solar system to make an extra gas giant,” says Kenyon.

    They propose that Planet Nine formed much closer to the Sun and then interacted with the other gas giants, particularly Jupiter and Saturn. A series of gravitational kicks then could have boosted the planet into a larger and more elliptical orbit over time.

    “Think of it like pushing a kid on a swing. If you give them a shove at the right time, over and over, they’ll go higher and higher,” explains Kenyon. “Then the challenge becomes not shoving the planet so much that you eject it from the solar system.”

    That could be avoided by interactions with the solar system’s gaseous disk, he suggests.

    Kenyon and Bromley also examine the possibility that Planet Nine actually formed at a great distance to begin with. They find that the right combination of initial disk mass and disk lifetime could potentially create Planet Nine in time for it to be nudged by Li’s passing star.

    “The nice thing about these scenarios is that they’re observationally testable,” Kenyon points out. “A scattered gas giant will look like a cold Neptune, while a planet that formed in place will resemble a giant Pluto with no gas.”

    Li’s work also helps constrain the timing for Planet Nine’s formation or migration. The Sun was born in a cluster where encounters with other stars were more frequent. Planet Nine’s wide orbit would leave it vulnerable to ejection during such encounters. Therefore, Planet Nine is likely to be a latecomer that arrived in its current orbit after the Sun left its birth cluster.

    Finally, Li and Adams looked at two wilder possibilities: that Planet Nine is an exoplanet that was captured from a passing star system, or a free-floating planet that was captured when it drifted close by our solar system. However, they conclude that the chances of either scenario are less than 2 percent.

    Li and Adams’ paper has been accepted for publication in the Astrophysical Journal Letters and is available online*. Kenyon and Bromley have submitted their findings to the Astrophysical Journal in two papers available online: one on in-situ formation** and one on gas-giant scattering***.

    *Science paper:
    Interaction Cross Sections and Survival Rates for Proposed Solar System Member Planet Nine

    **Science Paper:
    Making Planet Nine: Pebble Accretion at 250–750 AU in a Gravitationally Unstable Ring

    ***Science paper:
    Making Planet Nine: A Scattered Giant in the Outer Solar System

    See the full article here .

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    About CfA

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy. The long relationship between the two organizations, which began when the SAO moved its headquarters to Cambridge in 1955, was formalized by the establishment of a joint center in 1973. The CfA’s history of accomplishments in astronomy and astrophysics is reflected in a wide range of awards and prizes received by individual CfA scientists.

    Today, some 300 Smithsonian and Harvard scientists cooperate in broad programs of astrophysical research supported by Federal appropriations and University funds as well as contracts and grants from government agencies. These scientific investigations, touching on almost all major topics in astronomy, are organized into the following divisions, scientific departments and service groups.

     
  • richardmitnick 8:59 am on May 2, 2016 Permalink | Reply
    Tags: , , Planet Nine,   

    From Science Alert: “Physicists think they’ve finally figured out how to locate Planet Nine” 

    ScienceAlert

    Science Alert

    29 APR 2016
    BRENDAN COLE

    1
    Caltech/R. Hurt (IPAC)

    The hunt for our mysterious new neighbour is heating up.

    We keep hearing about Planet Nine – the proposed new planet in the Solar System that might be herding asteroids out past Pluto – but astronomers are having a hard time actually finding it.

    Planet nine orbit image Credit Caltech R. Hurt (IPAC)
    Planet nine orbit image Credit Caltech R. Hurt (IPAC)

    New planets and asteroids have only ever been found using reflected sunlight. Our Sun sends out light in all directions, and a tiny amount of it bounces off a planet or asteroid, then an even tinier amount bounces back towards Earth.

    Planet Nine probably receives around half a million times less sunlight than we do here on Earth, which is going to make finding it this way extremely tricky. But according to two new studies, we might be able to find it using light emanating from within the planet itself.

    Everything in the Universe emits what’s called black-body radiation, where hotter objects shine in more energetic light and cooler objects shine in less energetic light. It’s why metal starts to glow red or orange when it’s heated up. And it isn’t because objects suddenly get hot enough to start emitting light – they’re always emitting light, but the kind of light they emit changes as they get hotter.

    Once an object passes a certain temperature, the light it emits starts to overlap with the light we can see, and it looks like they’re glowing red-hot. Once they cool down, the light they emit goes back to being invisible to our eyes, but it’s still being emitted just the same.

    This is also why infrared goggles can find people: people glow in the infrared, and our warmer parts (our faces and torsos) glow in slightly different light than the cooler parts do.

    Black-body radiation gives us a way to see Planet Nine, which probably emits light that’s right on the border between the infrared and microwaves. Conveniently, we have telescopes that search the sky for light on the border of the infrared and microwaves.

    That’s the idea behind papers by two different teams that say we should use Planet Nine’s black-body radiation to first find it, and then learn more about it.

    The first group*, led by Nicolas B. Cowan from McGill University in Canada, started out by asking whether our telescopes could even see something as cold, slow, and distant as Planet Nine. In their paper, they give the current best estimates for how hot Planet Nine is and how much light it produces, which together with the distance to the planet tell them how bright it should be to us.

    They found that, unless their estimates are way off, we could probably find Planet Nine using current telescopes. The telescopes just need to be pointed in the right places.

    Even better, even if those estimates are a bit far off, Planet Nine will probably still be visible to telescopes that are currently being planned, they say. Either way, we’re probably on the cusp of detecting this new planet for the first time.

    The second group**, led by Sivan Ginzburg from the Hebrew University of Jerusalem, Israel, went even further, claiming that the specifics of its black-body radiation could teach us about Planet Nine’s size and its atmosphere.

    All of the planets in our Solar System have been cooling since they were formed about 5 billion years ago. The planets that have big, thick atmospheres have generally cooled much more slowly, because the atmospheres tend to act like big, thick blankets that trap the planet’s heat and slow down the cooling.

    By modelling Planet Nine with the assumption that it’s a lot like Uranus or Neptune, Ginzburg’s team was able to find a relationship between the thickness of its atmosphere, its mass, and the black-body radiation. So once we measure that radiation, we pretty much get the other two for free.

    Since we’re probably on the verge of detecting this radiation, it won’t be long before we know something about Planet Nine’s composition, too.

    The big physics news of 2016 was the discovery of gravitational waves. The big news of 2017 might be finding and understanding Planet Nine…

    The new papers have been published in The Astrophysical Journal Letters, and you can access them here* and here**.

    *Science paper:
    COSMOLOGISTS IN SEARCH OF PLANET NINE: THE CASE FOR CMB EXPERIMENTS

    **Science paper:
    BLACKBODY RADIATION FROM ISOLATED NEPTUNES

    See the full article here .

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  • richardmitnick 8:54 am on April 7, 2016 Permalink | Reply
    Tags: , , , Planet Nine   

    From GIZMODO: “How Astronomers Are Going to Find Planet Nine” 

    GIZMODO bloc

    GIZMODO

    4.7.16
    Maddie Stone

    Planet nine orbit image Credit Caltech R. Hurt (IPAC)
    Planet nine orbit image Credit Caltech R. Hurt (IPAC)

    Ten years ago, billions of humans had their worldview upended when a group of astronomers announced that the solar system only contains eight planets. Now, the same guys are trying to rewrite our childhood mnemonics once again. A ninth planet may exist after all, and it isn’t Pluto.

    In January, Caltech’s Konstantin Batygin and Mike Brown (the astronomer credited with killing Pluto) shared compelling evidence * of a planet larger than Earth and over five hundred times further from the Sun. Planet nine hasn’t been spotted—its existence is inferred by the improbable orbits of a handful of distant, icy objects. A race is on to find the mysterious world, and help is coming from all corners of the astronomical community.

    “I’ve never seen anything like this happen before,” Brown told Gizmodo. “People look at the evidence and they are convinced. It almost makes me worried.”

    Planet nine’s overwhelmingly positive reception is indeed rather odd. This isn’t the first time astronomers have speculated about a distant world sitting in or beyond the icy ring of primordial rocks known as the Kuiper belt. They’ve been doing so for decades. As Brown puts it, “Anytime anything funny happens in the outer solar system, somebody will jump up and down and say planet.”

    But in every prior instance when astronomers have cried planet, the case has unraveled upon further analysis. This time, the evidence has only grown stronger. The first hint came in 2003, when Brown spotted a 600 mile-wide object circling the Sun on a highly elliptical path, far beyond the outer limit of the Kuiper belt.

    Kuiper Belt. Minor Planet Center
    Kuiper Belt. Minor Planet Center

    1
    The orbit of Sedna (red) compared with the outer planets and Pluto (purple). Image: NASA

    Sedna, named after the Inuit goddess of the sea, was the coldest, most distant known object to orbit the Sun, and nobody could explain how it got there. In a paper published the following year, Brown and his colleagues speculated Sedna could have been dragged into its extreme orbit by a passing star or an unseen planet. For more than a decade, it remained an isolated curiosity.

    Then in 2014, astronomers Chad Trujillo and Scott Sheppard announced the discovery of another distant object on a Sedna-like orbit, followed by a set of six Kuiper belt objects that share a bizarre orbital feature. Each of these icy rocks traces an elliptical path that loops out in the exact same part of the solar system. What’s more, all of their orbits are all tilted the same direction, pointing about 30 degrees down relative to the ecliptic plane (the plane in which planets orbit the Sun).

    Based on our understanding of Kuiper belt dynamics, any one of these orbits is extremely unlikely. The chance of all six being some sort of grand cosmic coincidence? Approximately one in 14,000.

    That’s when Batygin, a theoretician, and Brown, an observer, decided to put their heads together. “Our initial goal was to demonstrate that this was not a planet—that it’s some other dynamical effect,” Batygin said.

    And yet, after two years of calculations and supercomputer simulations, a planet is what they found in the math. It turns out Sedna, all six Kuiper belt objects, and a handful of other weird rocks that orbit perpendicular to the plane of our solar system, can all be explained by a distant planet roughly ten times the mass of the Earth. “What we’re really predicting here is not just the existence of a planet, but a physical process through which the shape of the outer solar system is explained,” Batygin said.

    According to Batygin and Brown’s calculations, Planet nine sits in an elongated, “anti-aligned” orbit—its point of closest approach to the Sun is directly opposite that of all other planets. It takes the frigid world 10 to 20 thousand years to complete a full orbit, and at its furthest point, it’s roughly 1,200 Earth distances (a hundred billion miles) away.

    In January, Batygin and Brown published ** their findings in the Astrophysical Journal. The announcement that a ninth planet may exist after all was not only embraced by the millions of laypersons who could finally fill the dark, Pluto-shaped holes in their hearts, but also by the scientific community. Folks with expertise ranging from the Big Bang to Saturn’s rings started asking whether a phantom planet may be lurking in their data.

    At this point, if astronomers are correct about Planet nine, it’s only a matter of time before we find it.

    The obvious way to prove the existence of a planet is to actually see the thing. In Planet nine’s case, that’s going to be tricky, because objects thirty times further from the Sun than Neptune on a good day don’t reflect a lot of light. But Brown, who’s built a career around finding small, distant Kuiper belt objects, is optimistic that Planet nine can be spotted.

    “In principle, this is exactly the same thing we do to look for KBOs,” Brown said. “You take a picture, go back, take another picture later, and see if something moved. If you told me exactly where Planet nine was, I could find it pretty easily.”

    The trouble is, we don’t know where Planet nine is, and its entire orbit is freakin’ enormous. And while astronomers can bag hundreds of random Kuiper belt objects by simply pointing a telescope at the sky, finding a specific object way off in the cosmic boondocks is going to be tougher.

    “For KBOs, we’re interested in a statistical sample,” Brown said. “For Planet nine, we just want to find it. So we have to be very systematic about surveying the sky, and we can’t leave any patch undone.”

    The best instrument for this job—both in terms of sensitivity and wide field of view—is Subaru, an 8.2 meter optical-infrared telescope located on the dormant volcano of Mauna Kea, Hawaii.

    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
    NAOJ Subaru Telescope interior
    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    Batygin and Brown have already put in a request for time on the popular telescope this fall. Meanwhile, several of their colleagues are bringing the southern hemisphere into the planet hunt, using a well-placed dark energy camera at an observatory in Chile.

    DECam, built at FNAL
    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo
    DECam, built at FNAL, and the NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile

    But you don’t need to be good with a telescope to help find Planet nine. Agnès Fienga, a planetary dynamicist at the Nice Observatory in France, has an entirely different take on how we can locate the beast— NASA’s Cassini probe.

    NASA/ESA/ASI Cassini Spacecraft
    NASA/ESA/ASI Cassini Spacecraft

    Since 2003, Fienga and her colleagues have used radio ranging data collected by the Cassini probe’s navigational system to precisely track the motion of Saturn. By doing so, they’ve constructed detailed models of the movement of all planets and major asteroids in the solar system. When Batygin and Brown published an orbital trajectory for a ninth planet, Fienga realized that her models could help narrow the search. “It’s not too complicated to add a supplementary planet and just test the theory,” Fienga told Gizmodo.

    By sticking Planet nine in a solar system model calibrated with over ten years of Cassini data, Fienga and her colleagues have already ruled out half of the planet’s possible positions in the sky. “This study is awesome,” Batygin said, noting that the positions Fienga’s team eliminated include perihelion—the planet’s closest approach to the Sun. This independently confirms Batygin’s view that the planet currently sits in a more distant orbit.

    Meanwhile, Nick Cowan of McGill University has thought of yet another way we can detect Planet nine—through its heat signature. Even an icebox of a planet like this one emits a small amount of energy at millimeter radio wavelengths. This turns out to be the same type of energy cosmologists use to study the birth of the universe.

    “I am not an expert on Planet nine at all, nor am I a cosmologist,” Cowan, who studies the composition of exoplanet atmospheres, told Gizmodo. But when his colleague Gil Holder suggested that Planet nine’s heat signature might be detectable with the instruments used to study the cosmic microwave background (CMB)—the ubiquitous energy signature left over from the Big Bang—Cowan’s interest was piqued.

    Cosmic Microwave Background per ESA/Planck
    Cosmic Microwave Background per ESA/Planck

    ESA/Planck
    ESA/Planck

    “I did a calculation, and came up with a surface temperature of 20 to 40 Kelvin,” Cowan said. That’s insanely cold, and it means Planet nine radiates about 2,000 times less heat than Uranus or Neptune. “I thought this crackpot idea would be over at this point,” he said.

    When Cowan brought his calculations back to Holder, he learned he was mistaken. “Turns out, we use Uranus and Neptune to calibrate CMB [experiments] because they’re really bright,” he said. “2,000 times colder is totally doable.”

    Cowan, Holder, and Nathan Kaib of the University of Oklahoma wrote up a paper on the idea, which is currently in review at The Astrophysical Journal. Cowan is hopeful that next-generation cosmology experiments will be able to detect Planet nine, or at least narrow the search. And if we’re really lucky, that faint heat signature might already exist in somebody’s CMB data.

    Batygin, for his part, continues to run model simulations. Several weeks back, those models got a big boost when Michele Bannister of the University of Victoria, Canada, revealed yet another Kuiper belt object on the same funky orbit as Planet nine’s original flock of six. “Our biggest worry was that the next set of objects we discover are going to destroy the pattern—that our brains had somehow tricked us,” Batygin said. “Instead, the first new object is exactly where our models say it should be. It basically falls on the mean.”

    Although we should save the champagne for hard proof, most astronomers agree that the case for a large, unseen planet beyond the Kuiper belt has never looked better. “I am not one hundred percent sure if there is a planet or not,” Fienga said. “But I think in a year we should have almost a definite answer.”

    And if we do discover a Planet nine? It’ll certainly expand our perspective on the solar system, just as discoveries of Kuiper belt objects did in the early 2000s. It’ll help us piece together our celestial history—how the planets formed, why they’re all so different, and how they arrived in their present orbits. And it’ll shed light on the diversity of worlds we can expect to find orbiting other stars.

    “The most exciting thing about Planet nine to me is that it’s uncharted territory,” Cowan said. “You do the math and realize, you could easily hide a planet out there, maybe more than one. Nature is amazingly good at making planets, and she puts them wherever the hell she wants.”

    Batygin agrees. “I think the one thing we we can be certain of,” he said, “is that the solar system hasn’t run out of mysteries.”

    *OBSERVATIONAL CONSTRAINTS ON THE ORBIT AND LOCATION OF PLANET NINE IN THE OUTER
    SOLAR SYSTEM

    Science team:
    Konstantin Batygin & Michael E. Brown
    Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125

    **Cosmologists in Search of Planet Nine: the Case for CMB Experiments
    Science team:
    Nicolas B. Cowan1,2,3,4, Gil Holder2,3, Nathan A. Kaib5
    Affiliations:
    1 Department of Earth & Planetary Sciences, McGill University,
    3450 rue University, Montreal, QC, H3A 0E8, Canada
    email: nicolas.cowan@mcgill.ca
    2 Department of Physics, McGill University, 3600 rue University,
    Montreal, QC, H3A 2T8, Canada
    3 McGill Space Institute
    4 Institut de recherche sur les exoplanetes
    5 Homer L. Dodge Department of Physics & Astronomy, University
    of Oklahoma, 440 W. Brooks St., Norman, OK 73019,
    USA

    See the full article here .

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    “We come from the future.”

    GIZMOGO pictorial

     
  • richardmitnick 10:18 am on February 28, 2016 Permalink | Reply
    Tags: , , , Planet Nine   

    From Astronomy Now: “Researchers home in on likely whereabouts of Planet Nine” 

    Astronomy Now bloc

    Astronomy Now

    27 February 2016
    No writer credit found

    Planet nine orbit image Credit CaltechR. Hurt (IPAC)
    Planet nine orbit image. Credit Caltech R. Hurt (IPAC)

    Using observations from NASA’s Cassini spacecraft, a team of French astronomers from the Institut de mécanique céleste et de calcul des éphémérides (Observatoire de Paris / CNRS / UPMC / université Lille 1), and the laboratory GeoAzur (Observatoire de la Côte d’Azur / CNRS / Université de Nice-Sophia Antipolis / IRD) have been able to specify the possible positions of a ninth planet in the Solar System.

    NASA Cassini Spacecraft
    NASA/ESA/ASI Cassini

    This research was published on 22 February 2016 in Astronomy & Astrophysics letters.

    The Kuiper Belt Objects, small bodies similar to Pluto beyond Neptune, have a particular distribution that is difficult to explain by pure chance.

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

    This is what led Konstantin Batygin and Mike Brown at Caltech (US) to propose, in a paper published 20 January 2016 in The Astronomical Journal, the existence of a ninth planet of 10 Earth masses, whose perturbations on Kuiper Objects could have led to their current distribution. Using numerical simulations, the two scientists determined the possible orbit of this planet. To be able to reproduce the observed distribution of Kuiper Belt Objects, this orbit, with a semi-major axis of 700 astronomical units (1 AU is the mean distance between the Earth and Sun, 92,955,807.3 miles or 149,597,870.7 kilometres), must be very eccentric (e = 0.6) and inclined (i = 30°), but no constraint on the current position of the planet is proposed in the study of Batygin and Brown. This does not facilitate the task of observers who need to search in all possible directions in longitude to try and discover this planet.

    Since 2003, Agnès Fienga (astronomer at the Observatoire de la Côte d’Azur), Jacques Laskar (CNRS senior researcher) and their team have been developing the INPOP planetary ephemerides, which calculate the motion of planets in the Solar System with the highest accuracy. In particular, using data from the Cassini spacecraft (NASA / ESA / ASI), the distance between The Earth and Saturn is known with an uncertainty of about 100 metres. The researchers had the idea to use the INPOP model to test the possibility of adding a ninth planet in the Solar System, as proposed by Batygin and Brown.

    In the study published this week, the French team shows that depending on the position of the planet from its perihelion, the ninth planet induces perturbations in the orbit of Saturn that can be detected by analysing the radio data from the Cassini spacecraft, orbiting Saturn since 2004. The researchers were able to compute the effect induced by the ninth planet and to compare the perturbed orbit to the Cassini data.

    For an angle from perihelion of less than 85° or greater than -65°, the perturbations induced by the ninth planet are inconsistent with the observed Cassini distances. The result is the same for the sector from -130° to -100° (Fig.1). This result allows to exclude half of the directions in longitude, in which the planet cannot be found. On the other hand, it appears that for some directions, the addition of the ninth planet reduces the discrepancies between the model calculated by the astronomers and the observed data, by comparison to a model that does not include this ninth planet. This makes plausible the presence thereof of the ninth planet for an angle from perihelion between 104° and 134°, with a maximum probability for 117°.

    The existence of a ninth planet can only be confirmed by direct observation, but by restricting the possible directions of research, the French research team makes an important contribution to this quest.

    See the full article here .

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