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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Jan 20 2016, 06:56 PM
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#2
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Junior Member Group: Members Posts: 78 Joined: 20-September 14 Member No.: 7261 |
If they are mentioning 700 AU 700 AU is given as an example semi-major axis of a perturber, with from a cursory glance their possible range laying at 400 to 1500 AU semi-major axes. The minor planets cited as grouped by resonance with the hypothetical objext have semi-major axes of 150-600 AU. What NASA used as definition for the solar system for Voyager is the heliosphere, i.e. the extend to which the stellar wind of the Sun interferes with the interstellar medium; an object with aphelion (such as most long-period comets) beyond basically dips in and out of this bubble. The IAU definition of a planet does not have any distance limitation. The referred-to Hill Sphere of the Sun, being its gravitational influence zone, is probably the most appropriate measure when considering "interstellar companions" though. |
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Jan 21 2016, 06:46 AM
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#3
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Member Group: Members Posts: 204 Joined: 29-June 05 Member No.: 421 |
700 AU is given as an example semi-major axis of a perturber, with from a cursory glance their possible range laying at 400 to 1500 AU semi-major axes. Wow. If we launch a probe that goes at similar speed to voyager 1, it takes over 100 years to reach 400 AU. From the blog site, it sounds pretty likely this thing is sitting out near its aphelion. Seems like a multi-generation effort is needed to explore this. |
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Jan 21 2016, 05:15 PM
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#4
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Wow. If we launch a probe that goes at similar speed to voyager 1, it takes over 100 years to reach 400 AU. From the blog site, it sounds pretty likely this thing is sitting out near its aphelion. Seems like a multi-generation effort is needed to explore this. Unless we can resurrect the "Planet Imager" mission concept of a constellation of space interferometers. This next step to network several Terrestrial Planet Finder (TPF) systems was envisioned to image details on planets around other stars, though maybe it can be repurposed? Also, maybe new rocket technology will come along at some point if we want to speculate on that. Will a telescope like the LSST be able to locate this planet? And does this really clear out its orbit to qualify as a planet? -------------------- Steve [ my home page and planetary maps page ]
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Jan 21 2016, 06:06 PM
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#5
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Will a telescope like the LSST be able to locate this planet? And does this really clear out its orbit to qualify as a planet? That definition uses very unfortunate wording. A planet does not literally have to clear away all other objects close to its orbit. If that were so there would be NO planets in the Solar System (except maybe Mercury or Venus). Another equally acceptable wording is that a planet must gravitationally dominate its neighborhood, which does apply to all eight known planets in the Solar System, but not to any of the known dwarf planets. It appears that this "Planet Nine" would gravitationally dominate its neighborhood (indeed, that was how its existence was theorized), so it would qualify as a full planet. |
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Jan 22 2016, 03:36 AM
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#6
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Junior Member Group: Members Posts: 31 Joined: 8-October 12 Member No.: 6692 |
That definition uses very unfortunate wording. A planet does not literally have to clear away all other objects close to its orbit. If that were so there would be NO planets in the Solar System (except maybe Mercury or Venus). Another equally acceptable wording is that a planet must gravitationally dominate its neighborhood, which does apply to all eight known planets in the Solar System, but not to any of the known dwarf planets. It appears that this "Planet Nine" would gravitationally dominate its neighborhood (indeed, that was how its existence was theorized), so it would qualify as a full planet. Would that mean dear Pluto is back as a planet ? Whooopie ! |
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Jan 22 2016, 12:20 PM
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#7
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Would that mean dear Pluto is back as a planet ? Whooopie ! Nope. Pluto is far too small to have any significant gravitational effect on other objects in similar orbits. It's merely one of numerous bodies of similar or slightly smaller size in its region of the Solar System, none of which are gravitationally significant. The dominant mass in its region is Neptune, which does control which orbits around it are occupied and which are empty, through resonances. The possible "Planet Nine", on the other hand, would count as a full planet because of its huge gravitational impact on everything in its region of the Solar System. |
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