Planet Nine from Outer Space

[Ann]

New evidence suggests a ninth planet lurking at the edge of the solar system

Click to view full size image

Washington Post wrote:

Astronomers at the California Institute of Technology announced Wednesday that they have found new evidence of a giant icy planet lurking in the darkness of our solar system far beyond the orbit of Pluto. They are calling it "Planet Nine."

Their paper, published in the Astronomical Journal, describes the planet as about five to 10 times as massive as the Earth. But the authors, astronomers Michael Brown and Konstantin Batygin, have not observed the planet directly.

Instead, they have inferred its existence from the motion of recently discovered dwarf planets and other small objects in the outer solar system. Those smaller bodies have orbits that appear to be influenced by the gravity of

darkness of our solar system far beyond the orbit of Pluto. They are calling it "Planet Nine."

Their paper, published in the Astronomical Journal, describes the planet as about five to 10 times as massive as the Earth. But the authors, astronomers Michael Brown and Konstantin Batygin, have not observed the planet directly.

Instead, they have inferred its existence from the motion of recently discovered dwarf planets and other small objects in the outer solar system. Those smaller bodies have orbits that appear to be influenced by the gravity of a hidden planet – a "massive perturber." The astronomers suggest it might have been flung into deep space long ago by the gravitational force of Jupiter or Saturn.

Ann

[bystander]

Researchers Find Evidence of a Real Ninth Planet
California Institute of Technology | 2016 Jan 20

Click to play embedded YouTube video.

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun. ...

Evidence for a Distant Giant Planet in the Solar System - Konstantin Batygin, Michael E. Brown

• Astronomical Journal 151(2):22 (2016 Feb) DOI: 10.3847/0004-6256/151/2/22
  arXiv.org > astro-ph > arXiv:1601.05438 > 20 Jan 2016

[BMAONE23]

Since it is still unknown where (if) it is, and it sits well beyond Pluto, what are the odds of it being intersected by New Horizons as that little probe traverses the Kuiper Belt?

[neufer]

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Since it is still unknown where (if) it is, and it sits well beyond Pluto, what are the odds of it being intersected by New Horizons as that little probe traverses the Kuiper Belt?

About the same odds as that of a banana slug randomly traveling out from the Black Rock Desert and accidentally finding itself passing under the Reno Arch.

[nealmcb]

Since it is still unknown where (if) it is, and it sits well beyond Pluto, what are the odds of it being intersected by New Horizons as that little probe traverses the Kuiper Belt?

That's the kind of question I like!

New Horizons is headed next to 2014 MU65, which in Jan 2019 will be at about RA 19h 09m, Dec -20 deg 33': http://theskylive.com/2014mu69-info
I don't know what its trajectory after that will be, but I'm guessing it is in that general direction.

The most likely spot for Planet Nine would be where it spends most of its time, at aphelion. Based on my initial perusal of the paper and diagrams, the aphelion point for Planet Nine would be a bit west of the perihelion point for Sedna, which is close to RA 6h, Dec 14 degrees, in between Orion and Gemini. That is just about the opposite point in the sky from 2014 MU65. Furthermore, in the direction New Horizons is headed, Planet Nine would be near perihelion, and as they've already said, we would have already seen it if it was that close.

So pretty close to zero chance, indeed!

But it brings up the $64000 question: exactly where SHOULD we look for Planet Nine?

Does anyone have the data that underlie the diagram from the top of this thread? In the paper they say:

For our nominal simulation, we adopted a' = 700 AU, e' = 0.6, and m' = 10 m⊕, as before, and set the inclination and initial argument of perihelion of the perturber to i' = 30° and ω' = 150°, respectively.

But they don't seem to indicate the longitude of the ascending node that they used for it. The ascending nodes for the cluster seem to average around 100 degrees, and since Planet Nine has about the same inclination, and ascends thru the ecliptic at about the same place, it should be similar. But the diagram isn't quite symmetrical, with the ellipse of Planet Nine rotated a bit counter-clockwise from the orientation that would be opposite the average of the cluster.

So far based on my best guesses, I figure that the big constellations Hydra and Eridanus and Monoceros would be likely discovery spots, with Orion my favorite in the sweet spot.

[nealmcb]

Science Friday just interviewed Brown and Batygin: http://www.sciencefriday.com/segments/s ... anet-nine/

They said the best bet is that you would be looking towards it in the November sky, I think at midnight. That would be centered at RA 3h or 4h or so.

[bystander]

Planet 9 Takes Shape
University of Bern | 2016 Apr 07

Simulated structure of planet candidate 9. © Esther Linder, Christoph Mordasini, Universität Bern

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Astrophysicists at the University of Bern have modelled the evolution of the putative planet in the outer solar system. They estimate that the object has a present-day radius equal to 3.7 Earth radii and a temperature of minus 226 degrees Celsius.

How big and how bright is Planet 9 if it really exists? What is its temperature and which telescope could find it? These were the questions that Christoph Mordasini, professor at the University of Bern, and his PhD student Esther Linder wanted to answer when they heard about the possible additional planet in the solar system suggested by Konstantin Batygin and Mike Brown of the California Institute of Technology in Pasadena.

The Swiss scientists are experts in modelling the evolution of planets. They usually study the formation of young exoplanets in disks around other stars light years away and the possible direct imaging of these objects with future instruments such as the James Webb Space Telescope. Therefore, Esther Linder says: “For me candidate Planet 9 is a close object, although it is about 700 times further away as the distance between the Earth and the Sun.” The astrophysicists assume that Planet 9 is a smaller version of Uranus and Neptune – a small ice giant with an envelope of hydrogen and helium. With their planet evolution model they calculated how parameters like the planetary radius or the brightness evolved over time since the solar system has formed 4,6 billion of years ago. The study was financed by the research project of the Swiss National Science Foundation PlanetsInTime and the National Center for Competence in Research (NCCR) PlanetS. ...

Evolution and Magnitudes of Candidate Planet Nine - Esther F. Linder, Christoph Mordasini

• Astronomy & Astrophysics (accepted 24 Mar 2016) DOI: 10.1051/0004-6361/201628350
  arXiv.org > astro-ph > arXiv:1602.07465 > 24 Feb 2016 (v1), 06 Apr 2016 (v2)

[bystander]

Did the Sun Steal Planet Nine?
Universe Today | 2016 Apr 04

The calculated 10,000–20,000-year-long orbit of Planet Nine. The green circle is the orbit of Pluto. Credit: Nature/K. Batygin and M. E. Brown AJ 151, 22 (2016)

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One of the biggest new mysteries in our Solar System is the purported presence of a large and distant “Planet Nine,” traveling around the Sun in a twenty-thousand-year orbit far beyond Pluto. Although this far-flung world’s existence has yet to actually be confirmed (or even detected) some scientists are suggesting it might have originally been an exoplanet around a neighboring star, pilfered by our Sun during its impudent adolescence.

In January 2016 the remorseless “planet killer” Mike Brown — a Caltech professor and astronomer whose discovery of Eris in 2005 prompted the IAU’s reclassification of planets, thereby knocking Pluto from the official list — announced evidence for the existence of a “real” ninth planet orbiting the Sun four times farther than Pluto…and possibly even farther out than the Kuiper Belt is thought to extend. According to Brown and co-researcher Konstantin Batygin their Planet Nine may be almost as massive as Neptune, but they’re still on the hunt for it within the regions where they think it should be.

Formed five billion years ago in a cluster of other stars, our Sun once had hundreds if not thousands of stellar siblings (now long since dispersed through the nearby galaxy.) As the stars developed many likely had planets form around them, just as the Sun did, and with all the young star systems in such relatively close proximity it’s possible that some planets wound up ejected from their host star to be picked up — or possibly even outright stolen — by another. ...

Planet Nine might be an exoplanet stolen by the Sun
New Scientist | 2016 Apr 04

Is there an exoplanet in the Solar System? - Alexander J. Mustill, Sean N. Raymond, Melvyn B. Davies

• arXiv.org > astro-ph > arXiv:1603.07247 > 23 Mar 2016

Making Planet Nine: Pebble Accretion at 250--750 AU in a Gravitationally Unstable Ring - Scott J. Kenyon, Benjamin C. Bromley

• arXiv.org > astro-ph > arXiv:1603.08008 > 25 Mar 2016

[bystander]

Saturn Spacecraft Not Affected by Hypothetical Planet 9
NASA | JPL-Caltech | Cassini | 2016 Apr 08

Saturn as seen by NASA's Cassini spacecraft in 2008. Long-term tracking of the spacecraft's position has revealed no unexplained perturbations in Cassini's orbit. (Credit: NASA/JPL/SSI)

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Contrary to recent reports, NASA's Cassini spacecraft is not experiencing unexplained deviations in its orbit around Saturn, according to mission managers and orbit determination experts at NASA's Jet Propulsion Laboratory in Pasadena, California.

Several recent news stories have reported that a mysterious anomaly in Cassini's orbit could potentially be explained by the gravitational tug of a theorized massive new planet in our solar system, lurking far beyond the orbit of Neptune. While the proposed planet's existence may eventually be confirmed by other means, mission navigators have observed no unexplained deviations in the spacecraft's orbit since its arrival there in 2004. ...

A recent paper predicts that, if data tracking Cassini's position were available out to the year 2020, they might be used to reveal a "most probable" location for the new planet in its long orbit around the sun. However, Cassini's mission is planned to end in late 2017, when the spacecraft -- too low on fuel to continue on a longer mission -- will plunge into Saturn's atmosphere. ...

Constraints on the location of a possible 9th planet derived from the Cassini data - A. Fienga et al

• Astronomy & Astrophysics 587:L8 (Mar 2016) DOI: 10.1051/0004-6361/201628227
  arXiv.org > astro-ph > arXiv:1602.06116 > 19 Feb 2016 (v1), 23 Feb 2016 (v3)

[neufer]

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[bystander]

Planet Nine: A World That Shouldn't Exist
Harvard Smithsonian Center for Astrophysics | 2016 May 03

Artist's conception of Planet Nine. [Credit: Robert Hurt (Caltech/IPAC)]

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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. ...

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? ...

Interaction Cross Sections and Survival Rates for Proposed Solar System Member Planet Nine - Gongjie Li, Fred C. Adams

• arXiv.org > astro-ph > arXiv:1602.08496 > 26 Feb 2016 (v1), 26 Apr 2016 (v2)

Making Planet Nine: A Scattered Giant in the Outer Solar System - Benjamin C. Bromley, Scott J. Kenyon

• arXiv.org > astro-ph > arXiv:1603.08010 > 25 Mar 2016

[Doum]

Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely that the so-called Planet 9 is an exoplanet. This would make it the first exoplanet to be discovered inside our own solar system. The theory is that our sun, in its youth some 4.5 billion years ago, stole Planet 9 from its original star.

Read more at: http://phys.org/news/2016-05-theft-plan ... r.html#jCp



http://phys.org/news/2016-05-theft-planet-solar.html

[bystander]

Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely that the so-called Planet 9 is an exoplanet. This would make it the first exoplanet to be discovered inside our own solar system. The theory is that our sun, in its youth some 4.5 billion years ago, stole Planet 9 from its original star.

viewtopic.php?p=256192#p256192

[saturno2]

Very interesting

[bystander]

Extreme Trans-Neptunian Objects Lead the Way to Planet Nine
Information and Scientific News Service | 2016 Jun 13

In the race towards the discovery of a ninth planet in our solar system, scientists from around the world strive to calculate its orbit using the tracks left by the small bodies that move well beyond Neptune. Now, astronomers from Spain and University of Cambridge have confirmed, with new calculations, that the orbits of the six extreme trans-Neptunian objects that served as a reference to announce the existence of Planet Nine are not as stable as it was thought.

The orbits of the six extreme trans-Neptunian objects (in magenta) are mysteriously aligned in one direction, a configuration which can be explained by the presence of a Planet Nine (in orange) in our solar system, according to the Caltech astronomers. Credit: Caltech/R. Hurt (IPAC) [Diagram created using WorldWide Telescope]

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At the beginning of this year, the astronomers K. Batygin and M. Brown from the California Institute of Technology (Caltech, USA) announced that they had found evidence of the existence of a giant planet ‑with a mass ten times larger than Earth’s‑ in the confines of the Solar System. Moving in an unusually elongated orbit, the mysterious planet will take between 10,000 and 20,000 years to complete one revolution around the Sun.

In order to arrive at this conclusion, Batygin and Brown run computer simulations with input data based on the orbits of six extreme trans-Neptunian objects (ETNOs). Specifically, these ETNOs are: Sedna, 2012 VP₁₁₃, 2004 VN₁₁₂, 2007 TG₄₂₂, 2013 RF₉₈ and 2010 GB₁₇₄.

Now, however, brothers Carlos and Raúl de la Fuente Marcos, two freelance Spanish astronomers, together with scientist Sverre J. Aarseth from the Institute of Astronomy of the University of Cambridge (United Kingdom), have considered the question the other way around: How would the orbits of these six ETNOs evolve if a Planet Nine such as the one proposed by K. Batygin and M. Brown really did exist? The answer to this important question has been published in the journal ‘Monthly Notices of the Royal Astronomical Society’ (MNRAS). ...

In any case, the statistical and numerical evidence obtained by the authors, both through this and previous work, leads them to suggest that the most stable scenario is one in which there is not just one planet, but rather several more beyond Pluto, in mutual resonance, which best explains the results. “That is to say we believe that in addition to a Planet Nine, there could also be a Planet Ten and even more,” the Spanish astronomer points out. ...

Dynamical impact of the Planet Nine scenario: N-body experiments - C. de la Fuente Marcos, R. de la Fuente Marcos, S. J. Aarseth

• Monthly Notices of the RAS: Letters 460(1):L123 (2016 July 21) DOI: 10.1093/mnrasl/slw078
  arXiv.org > astro-ph > arXiv:1604.06241 > 21 Apr 2016 (v1), 09 May 2016 (v2)

Commensurabilities between ETNOs: a Monte Carlo survey - C. de la Fuente Marcos, R. de la Fuente Marcos

• Monthly Notices of the RAS: Letters 460(1):L64 (2016 July 21) DOI: 10.1093/mnrasl/slw077
  arXiv.org > astro-ph > arXiv:1604.05881 > 20 Apr 2016 (v1), 05 May 2016 (v2)

[rstevenson]

Those extra planets might some day come in handy (if we survive long enough.)

In Robert Zubrin's suggested variation of the Kardashev scale, he describes a Type II civilization as one that "has extensive colonies in its respective stellar system." (We're a Type I civilization now, on that scale.) Any such Type II civilization would need all the resources it could get its hands on, and icy worlds full of volatiles are excellent caches of such resources.

Rob

[bystander]

viewtopic.php?p=260165#p260165

[bystander]

Curious Tilt of the Sun Traced to Undiscovered Planet
California Institute of Technology | 2016 Oct 19

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. ...

Solar Obliquity Induced by Planet Nine - Elizabeth Bailey, Konstantin Batygin, Michael E. Brown

• Astronomical Journal 152(5):126 (2016 Nov) DOI: 10.3847/0004-6256/152/5/126
  arXiv.org > astro-ph > arXiv:1607.03963 > 14 Jul 2016 (v1), 20 Jul 2016 (v2)

[bystander]

More Evidence for Ninth Planet Roaming Solar System's Outer Fringes
University of Arizona |via PhysOrg | 2016 Oct 19

Known objects in the Kuiper belt beyond the orbit of Neptune. (Scale in AU; epoch as of January 2015.). Credit: Wikipedia/CC BY-SA 3.0

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As the search for a hypothetical, unseen planet far, far beyond Neptune's orbit continues, research by a team of the University of Arizona provides additional support for the possible existence of such a world and narrows the range of its parameters and location. ...

According to the researchers' calculations, such a hypothetical planet would complete one orbit around the Sun roughly every 17,000 years and, at its farthest point from our central star, it would swing out more than 660 astronomical units, with one AU being the average distance between the Earth and the Sun.

Scientists think that objects in the Kuiper Belt, a vast region of dwarf planets and icy rocks populating the fringes of our solar system beyond the orbit of Neptune, dance mostly to the tune of the giant planets, Saturn, Jupiter, Uranus and Neptune, influenced by their gravity either directly or indirectly.

However, there are a few known Kuiper Belt objects (KBOs) that are unlikely to be significantly perturbed by the known giant planets in their current orbits. Referred to as "extreme KBOs" (eKBOs) by the authors, all of these have extremely large orbital eccentricities, in other words, they get very close to the Sun at one point on their orbital journey, only to swing far out into space once they pass the Sun, on long elliptical orbits that take these strange mini worlds hundreds of AUs away from the Sun. ...

Corralling a distant planet with extreme resonant Kuiper belt objects - Renu Malhotra, Kathryn Volk, Xianyu Wang

• Astrophysical Journal Letters 824/2/L22 (2016 Jun 20) DOI: 10.3847/2041-8205/824/2/L22
  arXiv.org > astro-ph > arXiv:1603.02196 > 07 Mar 2016 (v1), 02 Jun 2016 (v3)

[bystander]

Does Our Solar System Have an Undiscovered
Planet? You Can Help Astronomers Find Out
Arizona State University | 2017 Feb 15

Previously known brown dwarf WISE 0855-0714 is seen here in this Backyard World flipbook as a moving orange dot at upper left. Citizen scientists will be asked to inspect images just like this to search for new objects in the solar neighborhood. (Credit: NASA/WISE)

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Arizona State University astronomer Adam Schneider and his colleagues are hunting for an elusive object lost in space between our Sun and the nearest stars. They are asking for your help in the search, using a new citizen-science website called Backyard Worlds: Planet 9.

Astronomers have found evidence for a ninth planet in our solar system. The evidence comes from studying the orbits of objects in the solar system’s Kuiper Belt. This is a zone of comet-like bodies orbiting the Sun out beyond the orbit of Neptune. The Kuiper Belt is similar to the asteroid belt that circles the Sun between Mars and Jupiter, but it lies dozens of times farther out.

This hypothetical Planet 9 could be similar in size to Neptune, but it may orbit up to a thousand times farther away from the Sun than the Earth does. So while astronomers can see its effects on the Kuiper Belt objects, no one has yet observed Planet 9 directly.

"If it exists, Planet 9 could be large — maybe 10 times the mass of Earth but orbiting far out beyond the Kuiper Belt," says Schneider. "Yet it must be extremely dim and hard to find." A postdoctoral researcher in ASU's School of Earth and Space Exploration, Schneider is particularly interested in studying objects smaller than fully fledged stars and ranging down in size to planets. ...

Looking for Citizen Scientists to Help Find Planet 9
University of California, Berkeley | 2017 Feb 15

NASA-Funded Website Lets the Public Search for New Nearby Worlds
NASA | GSFC | WISE | 2017 Feb 15

Searching for Planet Nine with Coadded WISE and NEOWISE-Reactivation Images - Aaron M. Meisner et al

• Astronomical Journal 153(2):65 (Feb 2017) DOI: 10.3847/1538-3881/153/2/65
  arXiv.org > astro-ph > arXiv:1611.00015 > 31 Oct 2016

[bystander]

The Curious Case of the Warped Kuiper Belt
University of Arizona | 2017 Jun 21

The plane of the solar system is warped in the outer reaches of the Kuiper Belt, signaling the presence of an unknown Mars-to-Earth-mass planetary object far beyond Pluto, according to new research from the UA.

A yet to be discovered, unseen "planetary mass object" makes its existence
known by ruffling the orbital plane of distant Kuiper Belt objects, according
to research by Kat Volk and Renu Malhotra of the UA's Lunar and Planetary
Laboratory. The object is pictured on a wide orbit far beyond Pluto in this
artist's illustration. (Image: Heather Roper/LPL)

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An unknown, unseen "planetary mass object" may lurk in the outer reaches of our solar system, according to new research on the orbits of minor planets to be published in the Astronomical Journal. This object would be different from — and much closer than — the so-called Planet Nine, a planet whose existence yet awaits confirmation.

n the paper, Kat Volk and Renu Malhotra of the University of Arizona's Lunar and Planetary Laboratory, or LPL, present compelling evidence of a yet-to-be- discovered planetary body with a mass somewhere between that of Mars and Earth. The mysterious mass, the authors show, has given away its presence — for now — only by controlling the orbital planes of a population of space rocks known as Kuiper Belt objects, or KBOs, in the icy outskirts of the solar system.

While most KBOs — debris left over from the formation of the solar system — orbit the sun with orbital tilts (inclinations) that average out to what planetary scientists call the invariable plane of the solar system, the most distant of the Kuiper Belt's objects do not. Their average plane, Volk and Malhotra discovered, is tilted away from the invariable plane by about eight degrees. In other words, something unknown is warping the average orbital plane of the outer solar system. ...

The Curiously Warped Mean Plane of the Kuiper Belt - Kathryn Volk, Renu Malhotra

• arXiv.org > astro-ph > arXiv:1704.02444 > 08 Apr 2017 (v1), 19 Jun 2017 (v2)

[bystander]

New Evidence in Support of the Planet Nine Hypothesis
Spanish Foundation for Science and Technology (FECYT) |
Information and Scientific News Service (SINC) | 2017 Jul 12

Last year, the existence of an unknown planet in our solar system was announced. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they point out that there is something perturbing them: a planet located at a distance between 300 to 400 times the Earth-Sun separation.

Will another planet be added to the list of planets in our solar system? Credit: NASA/JPL-Caltech

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Scientists continue to argue about the existence of a ninth planet within our solar system. At the beginning of 2016, researchers from the California Institute of Technology (Caltech, USA) announced that they had evidence of the existence of this object, located at an average distance of 700 AU or astronomical units (700 times the Earth-Sun separation) and with a mass ten times that of the Earth. Their calculations were motivated by the peculiar distribution of the orbits found for the trans-Neptunian objects (TNO) of the Kuiper belt, which apparently revealed the presence of a Planet Nine or X in the confines of the solar system.

However, scientists from the Canadian-French-Hawaiian project OSSOS detected biases in their own observations of the orbits of the TNOs, which had been systematically directed towards the same regions of the sky, and considered that other groups, including the Caltech group, may be experiencing the same issues. According to these scientists, it is not necessary to propose the existence of a massive perturber (a Planet Nine) to explain these observations, as these are compatible with a random distribution of orbits.

Now, however, two astronomers from the Complutense University of Madrid have applied a new technique, less exposed to observational bias, to study a special type of trans-Neptunian objects: the extreme ones (ETNOs, located at average distances greater than 150 AU and that never cross Neptune's orbit). For the first time, the distances from their nodes to the Sun have been analysed, and the results, published in the journal ‘MNRAS: Letters’, once again indicate that there is a planet beyond Pluto.

The nodes are the two points at which the orbit of an ETNO, or any other celestial body, crosses the plane of the solar system. These are the precise points where the probability of interacting with other objects is the largest, and therefore, at these points, the ETNOs may experience a drastic change in their orbits or even a collision. ...

Evidence for a Possible Bimodal Distribution of the Nodal Distances of the Extreme Trans-Neptunian Objects:
Avoiding a Trans-Plutonian Planet or Just Plain Bias? - C. de la Fuente Marcos, R. de la Fuente Marcos

• Monthly Notices of the RAS: Letters (online 26 Jun 2017) DOI: 10.1093/mnrasl/slx106
  arXiv.org > astro-ph > arXiv:1706.06981 > 21 Jun 2017 (v1), 22 Jun 2017 (v2)

[bystander]

The Super-Earth That Came Home for Dinner
NASA | JPL-Caltech | 2017 Oct 04

It might be lingering bashfully on the icy outer edges of our solar system, hiding in the dark, but subtly pulling strings behind the scenes: stretching out the orbits of distant bodies, perhaps even tilting the entire solar system to one side.

If a planet is there, it’s extremely distant and will stay that way (with no chance -- in case you’re wondering -- of ever colliding with Earth, or bringing “days of darkness”). It is a possible “Planet Nine” -- a world perhaps 10 times the mass of Earth and 20 times farther from the Sun than Neptune. The signs so far are indirect, mainly its gravitational footprints, but that adds up to a compelling case nonetheless.

One of its most dedicated trackers, in fact, says it is now harder to imagine our solar system without a Planet Nine than with one.

“There are now five different lines of observational evidence pointing to the existence of Planet Nine,” said Konstantin Batygin, a planetary astrophysicist at Caltech in Pasadena, California, whose team may be closing in. “If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them.” ...

Evidence for a Distant Giant Planet in the Solar System - Konstantin Batygin, Michael E. Brown

• Astronomical Journal 151(2):22 (2016 Feb) DOI: 10.3847/0004-6256/151/2/22
  arXiv.org > astro-ph > arXiv:1601.05438 > 20 Jan 2016

http://asterisk.apod.com/viewtopic.php?p=253090#p253090

Solar Obliquity Induced by Planet Nine - Elizabeth Bailey, Konstantin Batygin, Michael E. Brown

• Astronomical Journal 152(5):126 (2016 Nov) DOI: 10.3847/0004-6256/152/5/126
  arXiv.org > astro-ph > arXiv:1607.03963 > 14 Jul 2016 (v1), 20 Jul 2016 (v2)

http://asterisk.apod.com/viewtopic.php?p=263394#p263394

[MargaritaMc]

These are the most recent posts on the dedicated, and detailed, blog that Batygin and Brown maintain regarding the search for planet 9.

• 30 June 2017
http://www.findplanetnine.com/2017/06/ status update pt 1 by Konstantin Batygin

• 2 July 2017
http://www.findplanetnine.com/2017/07/ status update pt 2 by Konstantin Batygin

• 21 September 2017
http://www.findplanetnine.com/2017/09/ status update by Mike Brown

[MargaritaMc]

Recent update from Konstantin Batygin on developments in a theory to underly the Planet Nine simulations:

http://www.findplanetnine.com/2017/10/theory.html
[...]Planet Nine is invoked to explain (1) physical clustering of distant Kuiper belt orbits, (2) the perihelion detachment of long-period KBOs such as Sedna and VP113, as well as (3) the origin of nearly-perpendicular orbits of centaurs in the solar system. Embarrassingly, until recently our understanding of the “machinery” behind how Planet Nine generates these observational signatures has been incomplete. That is, although we have plenty of numerical experiments to demonstrate that Planet Nine can nicely reproduce the observed solar system, the theory that underlies these simulations has remained largely elusive.

The good news is that this is no longer a problem. In a recently accepted paper that I co-authored with Alessandro “Morby” Morbidelli, the theory of Planet Nine is characterized from semi-analytical grounds. So, for the first time, we not only know what Planet Nine does to the distant Kuiper belt, but we understand how it does it.

Refers to:

Dynamical Evolution Induced by Planet Nine
Konstantin Batygin, Alessandro Morbidelli
(Submitted to the arXiv on 4 Oct 2017, accepted for publication in the Astronomical Journal)
https://arxiv.org/abs/1710.01804

ABSTRACT:
The observational census of trans-Neptunian objects with semi-major axes greater than ~250 AU exhibits unexpected orbital structure that is most readily attributed to gravitational perturbations induced by a yet-undetected, massive planet. Although the capacity of this planet to (i) reproduce the observed clustering of distant orbits in physical space, (ii) facilitate dynamical detachment of their perihelia from Neptune, and (iii) excite a population of long-period centaurs to extreme inclinations is well established through numerical experiments, a coherent theoretical description of the dynamical mechanisms responsible for these effects remains elusive. In this work, we characterize the dynamical processes at play, from semi-analytic grounds. We begin by considering a purely secular model of orbital evolution induced by Planet Nine, and show that it is at odds with the ensuing stability of distant objects. Instead, the long-term survival of the clustered population of long-period KBOs is enabled by a web of mean-motion resonances driven by Planet Nine. Then, by taking a compact-form approach to perturbation theory, we show that it is the secular dynamics embedded within these resonances that regulates the orbital confinement and perihelion detachment of distant Kuiper belt objects. Finally, we demonstrate that the onset of large-amplitude oscillations of orbital inclinations is accomplished through capture of low-inclination objects into a high-order secular resonance and identify the specific harmonic that drives the evolution. In light of the developed qualitative understanding of the governing dynamics, we offer an updated interpretation of the current observational dataset within the broader theoretical framework of the Planet Nine hypothesis.