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Thread: Is Planet Nine almost certain, probable, possible or unlikely?

  1. #61
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    In 1992, the discovery of a small object unlocked a big secret: that the solar system was far more vast than we’d ever imagined. Before, we’d only confirmed the existence of lonely, strange, cold Pluto, in a region of space called the Kuiper Belt. The Kuiper Belt is a grouping of icy objects located in an area just outside the orbit of Neptune—like a colder, more watery asteroid belt. Up until 1992, it had been strictly theoretical because no one had observed anything beyond Pluto. The discovery of 1992 QB1 marked only the second time an object in the Kuiper Belt had been found. In the next few years, discoveries of these small, cold worlds snowballed—80+ were found between 1992 and 1999, and hundreds are known today. With the outer solar system surveys at Mauna Kea and La Palma observatories in the 1990s, we finally began to unlock the “third zone” of the solar system as something more than theoretical.
    First the author says the solar system was more vast than we had ever imagined, and then he acknowledges that there were theories about stuff beyond Pluto. That means we had imagined it. Yet another example of questionable writing by a popular media writer.

  2. #62
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    Quote Originally Posted by Hornblower View Post
    First the author says the solar system was more vast than we had ever imagined, and then he acknowledges that there were theories about stuff beyond Pluto. That means we had imagined it. Yet another example of questionable writing by a popular media writer.
    Pedants' Corner

    If you assume the word "we" refers to a section or grouping of people who had never imagined this, but there are other people who are not members of this group, strictly speaking it makes grammatical sense.

    It's not what he or she meant though !

  3. #63
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    How much nicer it would have been for the author to have presented the history of the Belt’s existence by going from early speculations by several scientists to real hypotheses, which doesn’t compare as well as is suggested for this new region.
    We know time flies, we just can't see its wings.

  4. #64
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    Now another explanation for the erratic movement of these worlds in the Kuiper belt. This explanation does not need a planet 9.

    https://www.colorado.edu/today/2018/...ective-gravity

    Bumper car-like interactions at the edges of our solar system—and not a mysterious ninth planet—may explain the the dynamics of strange bodies called “detached objects,” according to a new study.

    CU Boulder Assistant Professor Ann-Marie Madigan and a team of researchers have offered up a new theory for the existence of planetary oddities like Sedna—an icy minor planet that circles the sun at a distance of nearly 8 billion miles. Scientists have struggled to explain why Sedna and a handful of other bodies at that distance look separated from the rest of the solar system.

    One theory suggests that an as-of-yet-unseen ninth planet lurking beyond Neptune may have kicked up the orbits of these detached objects.

    But Madigan and her colleagues calculated that the orbits of Sedna and its ilk may result from these bodies jostling against each other and space debris in the outer solar system.

    “There are so many of these bodies out there. What does their collective gravity do?” said Madigan of the Department of Astrophysical and Planetary Sciences (APS) and JILA. “We can solve a lot of these problems by just taking into account that question.”

    The researchers presented their findings today at a press briefing at the 232nd meeting of the American Astronomical Society, which runs from June 3-7 in Denver, Colorado.

  5. #65
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    On the other hand, here is a suggestion that Sedna et al may have been perturbed by numerous planetoids:
    https://www.colorado.edu/today/2018/...ective-gravity
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  6. #66
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    One thing about that citizen science project looking for the planet, if anyone succeeds and flags up the thing will they be allowed to become immortal?

  7. #67
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    Quote Originally Posted by peteshimmon View Post
    One thing about that citizen science project looking for the planet, if anyone succeeds and flags up the thing will they be allowed to become immortal?
    Presuming you mean will they name the planet after its discoverer, that seems unlikely to me. The IAU has sole competency in recognising planet names. All other recognised planets have names from ancient mythology.

    "Eris" was not called "Brown" for example, and that is only a dwarf planet. The naming of a proper large planet would come under even more scrutiny.

    Having said that, the discoverer will be immortal as the discoverer.

  8. #68
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    Quote Originally Posted by kzb View Post
    Presuming you mean will they name the planet after its discoverer, that seems unlikely to me. The IAU has sole competency in recognising planet names. All other recognised planets have names from ancient mythology.
    Yes, there was once a planet named George. Perhaps Herschel didn't help things with this, though I kinda like it for some reason.
    We know time flies, we just can't see its wings.

  9. #69
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    Quote Originally Posted by selvaarchi View Post
    Now another explanation for the erratic movement of these worlds in the Kuiper belt. This explanation does not need a planet 9.

    https://www.colorado.edu/today/2018/...ective-gravity
    Is it possible that the occasional close passage of other Stars could also have caused the observed erratic orbits?

  10. #70
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    From Space.com:

    The collective-gravity hypothesis isn't a silver bullet, however. For example, there's still "clustering in pomega," which Madigan described as the odd fact that the orbits of the detached objects all tilt the same way.
    "Planet Nine explains this really well, and we do not," Madigan said.
    Ironically, while the new research discounts the need for an undiscovered planet, it requires the presence of thousands of smaller unseen objects.


    "Take your pick," it would seem, but I know which way I tilt. Ha!
    Where the telescope ends, the microscope begins. Which of the two has the greater view?

  11. #71
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    Quote Originally Posted by George View Post
    Yes, there was once a planet named George. Perhaps Herschel didn't help things with this, though I kinda like it for some reason.
    I have read that, several decades later, Leverrier was interested in reviving that designation.

  12. #72
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    Quote Originally Posted by ngc3314 View Post
    I have read that, several decades later, Leverrier was interested in reviving that designation.
    A Frenchman honoring King George? . That’s surprising. He was credited for discovering, via the math of dancing George, Neptune, which was, apparently, his suggestion. That might have something to do with supporting Herschel but I doubt it. Any idea why he would favor George? Did he have inside info on a plot by the Germans to consciously engage in planetary naming pun-ishment? I doubt that, too.

    Saturn...George...Jean...Clyde. I like it.
    We know time flies, we just can't see its wings.

  13. #73
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    I was looking through the abstracts when a single word leaped out at me. I realized then I had not kept up with the latest Outer Planet research at all.

    ============================

    http://adsabs.harvard.edu/abs/2018AJ....155..243T

    On the Detectability of Planet X with LSST

    Trilling, David E.; Bellm, Eric C.; Malhotra, Renu
    06/2018

    TWO planetary mass objects in the far outer solar system---collectively referred to here as Planet X--- have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the ``wide-fast-deep (WFD)'' survey) of the southern sky beginning in 2022, and it will therefore be an important tool in searching for these hypothesized planets. Here, we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the WFD survey plus additional coverage), we estimate that LSST will confidently detect or rule out the existence of Planet X in 61% of the entire sky. At orbital distances up to ~75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a nondetection of Planet X in LSST data.

    =============================

    [Emphasis mine.] I went to the article itself, and lo, it was not TWO Planet X's, it seemed to be a LOT. Or maybe just disagreements about ONE. Hard to tell.

    =============================

    https://arxiv.org/pdf/1804.07713.pdf

    "The possibility of undiscovered planets in the solar system has long fascinated astronomers and the public alike. Recent studies of the orbital properties of very distant Kuiper belt objects (KBOs) have identified several anomalies that may be due to the gravitational influence of one or more undiscovered planetary mass objects orbiting the Sun at distances comparable to the distant KBOs. Trujillo & Sheppard (2014) and Sheppard & Trujillo (2016) noted a clustering of the argument of perihelion (the angular position of the perihelion relative to the ascending node of an orbit on the J2000 reference plane) of KBOs whose semi-major axes exceed 150 au. Subsequently, Batygin & Brown (2016) and Brown & Batygin (2016) noted a clustering of the longitudes of perihelion and of the orbit poles of the same group of distant KBOs. Malhotra et al. (2016) noted that the most distant KBOs have near-integer period ratios, suggestive of dynamical resonances with a massive perturber. These orbital distribution peculiarities could be caused by an unseen massive body. Trujillo & Sheppard (2014) estimate a super-Earth mass object orbiting at a heliocentric distance & 250 au (while noting that a range of parameters for an unseen parameter could produce the observational signature that they observe); Brown & Batygin (2016) estimate a planet of mass 5–20 M⊕ in an orbit of semi-major axis 380–980 au, perihelion distance 150–350 au and moderately inclined (~30◦) to the ecliptic; and Malhotra et al. (2016) suggest a ~10 M⊕ planet in an orbit of semi-major axis ~665 au of moderate eccentricity and two possible inclinations (i  18◦ or i  48◦ to the ecliptic). The observational sample size for the above analyses is relatively small, 6–13 objects, depending upon choice of perihelion distance cut-off. Finally, in a separate line of argument, Bailey et al. (2016) and Gomes et al. (2017) show that the obliquity of the Sun of around 6 degrees can be explained by a 10–20 M⊕ perturber with a semi-major axis of 400–600 au. Separately, for a larger sample of ~160 distant KBOs whose semi-major axes are in the range 50–80 au, Volk & Malhotra (2017) reported a strong deviation of the mid-plane from the Solar System’s invariable plane. Based on this deviation, they suggest the presence of a smaller planetary mass object of mass 0.1–2.4 M⊕ at distance 60–100 au in an orbit inclined to the ecliptic by a few to a few tens of degrees. The predicted locations (in the sky) and brightnesses for these massive unseen objects — here referred to collectively as “Planet X” — are sufficiently unconstrained that large area sky surveys must be carried out. Such surveys require moderately large telescopes — a distant planet may be as bright as V=15 (Volk & Malhotra 2017) or as faint as V=22–25 (Brown & Batygin 2016) — and very large fields of view, as the search regions are at least hundreds of square degrees, and could easily be thousands.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  14. #74
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    NEW PAPER!!

    https://arxiv.org/abs/1808.01248

    The Influence of Planet 9 on the Orbits of Distant TNOs: The Case for a Low Perihelion Planet

    Jessica Cáceres, Rodney Gomes
    (Submitted on 3 Aug 2018)

    The hypothesis of an additional planet in the outer Solar System has gained new support as a result of the confinement noted in the angular orbital elements of distant trans-Neptunian objects. Orbital parameters proposed for the external perturber suggest semimajor axes between 500 and 1000 au, perihelion distances between 200 and 400 au for masses between 10 and 20 M⊕. In this paper we study the possibility that lower perihelion distances for the additional planet can lead to angular confinements as observed in the population of objects with semimajor axes greater than 250 au and perihelion distances higher than 40 au. We performed numerical integrations of a set of particles subjected to the influence of the known planets and the putative perturber during the age of the Solar System and compared our outputs with the observed population through a statistical analysis. Our investigations showed that lower perihelion distances from the outer planet usually lead to more substantial confinements than higher ones, while retaining the Classical Kuiper Belt as well as the ratio of the number of detached with perihelion distances higher than 42 au to scattering objects in the range of semimajor axes from 100 au to 200 au.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  15. #75
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    https://arxiv.org/abs/1805.05355

    Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination

    J. C. Becker, T. Khain, S. J. Hamilton, F. Adams, D. W. Gerdes, L. Zullo, K. Franson, S. Millholland, G. M. Bernstein, M. Sako, P. Bernardinelli, K. Napier, L. Markwardt, Hsing Wen Lin, W. Wester, F. B. Abdalla, S. Allam, J. Annis, S. Avila, E. Bertin, D. Brooks, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, C. E. Cunha, C. B. D'Andrea, L. N. da Costa, C. Davis, J. De Vicente, H. T. Diehl, P. Doel, T. F. Eifler, B. Flaugher, P. Fosalba, J. Frieman, J. Garcia-Bellido, E. Gaztanaga, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, W. G. Hartley, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, M. A. G. Maia, M. March, J. L. Marshall, F. Menanteau, R. Miquel, R. L. C. Ogando, A. A. Plazas, E. Sanchez, V. Scarpine, R. Schindler, I. Sevilla-Noarbe, M. Smith, R. C. Smith, et al. (5 additional authors not shown)
    (Submitted on 14 May 2018 (v1), last revised 6 Aug 2018 (this version, v2))

    We report the discovery and dynamical analysis of 2015 BP519, an extreme Trans-Neptunian Object detected by the Dark Energy Survey at a heliocentric distance of 55 AU and absolute magnitude Hr= 4.3. The current orbit, determined from a 1110-day observational arc, has semi-major axis a≈450 AU, eccentricity e≈0.92 and inclination i≈54 degrees. With these orbital elements, 2015 BP519 is the most extreme TNO discovered to date, as quantified by the reduced Kozai action, which is a conserved quantity at fixed semi-major axis a for axisymmetric perturbations. We discuss the orbital stability and evolution of this object in the context of the known Solar System, and find that 2015 BP519 displays rich dynamical behavior, including rapid diffusion in semi-major axis and more constrained variations in eccentricity and inclination. We also consider the long term orbital stability and evolutionary behavior within the context of the Planet Nine Hypothesis, and find that BP519 adds to the circumstantial evidence for the existence of this proposed new member of the Solar System, as it would represent the first member of the population of high-i,
    ϖ-shepherded TNOs.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  16. #76
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    https://arxiv.org/abs/1712.06547

    Chaotic Dynamics of Trans-Neptunian Objects Perturbed by Planet Nine

    Sam Hadden, Gongjie Li, Matthew J. Payne, Matthew J. Holman
    (Submitted on 18 Dec 2017 (v1), last revised 1 May 2018 (this version, v2))

    Observations of clustering among the orbits of the most distant trans-Neptunian objects (TNOs) has inspired interest in the possibility of an undiscovered ninth planet lurking in the outskirts of the solar system. Numerical simulations by a number of authors have demonstrated that, with appropriate choices of planet mass and orbit, such a planet can maintain clustering in the orbital elements of the population of distant TNOs, similar to the observed sample. However, many aspects of the rich underlying dynamical processes induced by such a distant eccentric perturber have not been fully explored. We report the results of our investigation of the dynamics of coplanar test-particles that interact with a massive body on an circular orbit (Neptune) and a massive body on a more distant, highly eccentric orbit (the putative Planet Nine). We find that a detailed examination of our idealized simulations affords tremendous insight into the rich test-particle dynamics that are possible. In particular, we find that chaos and resonance overlap plays an important role in particles' dynamical evolution. We develop a simple mapping model that allows us to understand, in detail, the web of overlapped mean-motion resonances explored by chaotically evolving particles. We also demonstrate that gravitational interactions with Neptune can have profound effects on the orbital evolution of particles. Our results serve as a starting point for a better understanding of the dynamical behavior observed in more complicated simulations that can be used to constrain the mass and orbit of Planet 9.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  17. #77
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    https://arxiv.org/abs/1712.04950

    A 3pi Search for Planet Nine at 3.4 microns with WISE and NEOWISE

    A. M. Meisner, B. C. Bromley, S. J. Kenyon, T. E. Anderson
    (Submitted on 13 Dec 2017)

    The recent 'Planet Nine' hypothesis has led to many observational and archival searches for this giant planet proposed to orbit the Sun at hundreds of astronomical units. While trans-Neptunian object searches are typically conducted in the optical, models suggest Planet Nine could be self-luminous and potentially bright enough at ~3-5 microns to be detected by the Wide-field Infrared Survey Explorer (WISE). We have previously demonstrated a Planet Nine search methodology based on time-resolved WISE coadds, allowing us to detect moving objects much fainter than would be possible using single-frame extractions. In the present work, we extend our 3.4 micron (W1) search to cover more than three quarters of the sky and incorporate four years of WISE observations spanning a seven year time period. This represents the deepest and widest-area WISE search for Planet Nine to date. We characterize the spatial variation of our survey's sensitivity and rule out the presence of Planet Nine in the parameter space searched at W1 < 16.7 in high Galactic latitude regions (90% completeness).
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

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