Researchers Find Evidence Of Distant Outer Planet |
Researchers Find Evidence Of Distant Outer Planet |
Jan 20 2016, 04:58 PM
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#1
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Free to view paper:
Evidence for a Distant Giant Planet in the Solar System Konstantin Batygin and Michael E. Brown QUOTE Abstract Recent analyses have shown that distant orbits within the scattered disk population of the Kuiper Belt exhibit an unexpected clustering in their respective arguments of perihelion. While several hypotheses have been put forward to explain this alignment, to date, a theoretical model that can successfully account for the observations remains elusive. In this work we show that the orbits of distant Kuiper Belt objects (KBOs) cluster not only in argument of perihelion, but also in physical space. We demonstrate that the perihelion positions and orbital planes of the objects are tightly confined and that such a clustering has only a probability of 0.007% to be due to chance, thus requiring a dynamical origin. We find that the observed orbital alignment can be maintained by a distant eccentric planet with mass gsim10 m⊕ whose orbit lies in approximately the same plane as those of the distant KBOs, but whose perihelion is 180° away from the perihelia of the minor bodies. In addition to accounting for the observed orbital alignment, the existence of such a planet naturally explains the presence of high-perihelion Sedna-like objects, as well as the known collection of high semimajor axis objects with inclinations between 60° and 150° whose origin was previously unclear. Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet. QUOTE 6. SUMMARY To date, the distinctive orbital alignment observed within the scattered disk population of the Kuiper Belt remains largely unexplained. Accordingly, the primary purpose of this study has been to identify a physical mechanism that can generate and maintain the peculiar clustering of orbital elements in the remote outskirts of the solar system. Here, we have proposed that the process of resonant coupling with a distant, planetary mass companion can explain the available data, and have outlined an observational test that can validate or refute our hypothesis. We began our analysis with a re-examination of the available data. To this end, in addition to the previously known grouping of the arguments of perihelia (Trujillo & Sheppard 2014), we have identified ancillary clustering in the longitude of the ascending node of distant KBOs and showed that objects that are not actively scattering off of Neptune exhibit true orbital confinement in inertial space. The aim of subsequent calculations was then to establish whether gravitational perturbations arising from a yet-unidentified planetary-mass body that occupies an extended, but nevertheless bound, orbit can adequately explain the observational data. The likely range of orbital properties of the distant perturber was motivated by analytic considerations, originating within the framework of octupole-order secular theory. By constructing secular phase-space portraits of a strictly planar system, we demonstrated that a highly eccentric distant perturber can drive significant modulation of particle eccentricities and libration of apsidal lines such that the perturber's orbit continuously encloses interior KBOs. Intriguingly, numerical reconstruction of the projected phase-space portraits revealed that, in addition to secular interactions, resonant coupling may strongly affect the dynamical evolution of KBOs residing within the relevant range of orbital parameters. More specifically, direct N-body calculations have shown that grossly overlapped, apsidally anti-aligned orbits can be maintained at nearly Neptune-crossing eccentricities by a highly elliptical perturber, resulting in persistent near-colinearity of KBO perihelia. Having identified an illustrative set of orbital properties of the perturber in the planar case, we demonstrated that an inclined object with similar parameters can dynamically carve a population of particles that is confined both apsidally and nodally. Such sculpting leads to a family of orbits that is clustered in physical space, in agreement with the data. Although the model proposed herein is characterized by a multitude of quantities that are inherently degenerate with respect to one another, our calculations suggest that a perturber on an a' ~ 700 AU, e' ~ 0.6 orbit would have to be somewhat more massive (e.g., a factor of a few) than m' = 10 m⊕ to produce the desired effect. A unique prediction that arises within the context of our resonant coupling model is that the perturber allows for the existence of an additional population of high-perihelion KBOs that do not exhibit the same type of orbital clustering as the identified objects. Observational efforts aimed at discovering such objects, as well as directly detecting the distant perturber itself constitute the best path toward testing our hypothesis. So about the size of Neptune, if their hypothesis is correct. |
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Sep 1 2016, 01:18 AM
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#2
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
New Extreme Trans-Neptunian Objects: Towards a Super-Earth in the Outer Solar System
QUOTE We are conducting a wide and deep survey for extreme distant solar system objects. Our goal is to understand the high perihelion objects Sedna and 2012 VP113 and determine if an unknown massive planet exists in the outer solar system. The discovery of new extreme objects from our survey of some 1080 square degrees of sky to over 24th magnitude in the r-band are reported. Two of the new objects, 2014 SR349 and 2013 FT28, are extreme detached trans-Neptunian objects, which have semi-major axes greater than 150 AU and perihelia well beyond Neptune (q>40 AU). Both new objects have orbits with arguments of perihelia within the range of the clustering of this angle seen in the other known extreme objects. One of these objects, 2014 SR349, has a longitude of perihelion similar to the other extreme objects, but 2013 FT28, which may have more significant Neptune interactions, is about 180 degrees away or anti-aligned in its longitude of perihelion. We also discovered the first outer Oort cloud object with a perihelion beyond Neptune, 2014 FE72. We discuss these and other interesting objects discovered in our ongoing survey. All the high semi-major axis (a>150 AU) and high perihelion (q>35 AU) bodies follow the previously identified argument of perihelion clustering between 290 and 40 degrees as first reported and explained as being from an unknown massive planet by Trujillo and Sheppard (2014), which some have called Planet X or Planet 9. We also report objects with lower perihelia (q<35 AU) and a>200 AU show arguments of perihelia clustering at the opposite angles between 100 and 200 degrees. Finally, we find that the longitude of perihelion is significantly correlated with the argument of perihelion for all extreme objects.
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