WISE & NEOWISE Cannot Find Planet Nine

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

Authors:

Meisner et al

Abstract:
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 less than 16.7 in high Galactic latitude regions (90% completeness).

Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine

Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine

Authors:

Batygin et al

Abstract:

The trans-Neptunian region of the solar system exhibits an intricate dynamical structure, much of which can be explained by an instability-driven orbital history of the giant planets. However, the origins of a highly inclined, and in certain cases retrograde, population of trans-Neptunian objects remain elusive within the framework of this evolutionary picture. In this work, we show that the existence of a distant, Neptune-like planet that resides on an eccentric and mildly inclined orbit fully accounts for the anomalous component the trans-Neptunian orbital distribution. Adopting the same parameters for Planet Nine as those previously invoked to explain the clustering of distant Kuiper belt orbits in physical space, we carry out a series of numerical experiments which elucidate the physical process though which highly inclined Kuiper belt objects with semi-major axes smaller than 100 AU are generated. The identified dynamical pathway demonstrates that enigmatic members of the Kuiper belt such as Drac and Niku are derived from the extended scattered disk of the solar system.

Doubts About Planet Nine?

Consequences of a Distant Massive Planet on the Large Semi-major Axis Trans-Neptunian Objects

Authors:

Shankman et al

Abstract:

We explore the distant giant planet hypothesis by integrating the large semi-major axis, large pericenter Trans-Neptunian Objects (TNOs) in the presence of the giant planets and an external perturber whose orbit is consistent with the proposed distant, eccentric, and inclined giant planet, so called planet 9. We find that TNOs with semi-major axes greater than 250 au experience some longitude of perihelion shepherding, but that a generic outcome of such evolutions is that the TNOs evolve to larger pericenter orbits, and commonly get raised to retrograde inclinations. This pericenter and inclination evolution requires a massive disk of TNOs (tens of M$_\Earth$) in order to explain the detection of the known sample today. Some of the highly inclined orbits produced by the examined perturbers will be inside of the orbital parameter space probed by prior surveys, implying a missing signature of the 9th planet scenario. The distant giant planet scenarios explored in this work do not reproduce the observed signal of simultaneous clustering in argument of pericenter, longitude of the ascending node, and longitude of perihelion in the region of the known TNOs.

Niku: a Retrograde Orbiting Trans Neptunian Object

Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs

Authors:

Chen et al

Abstract:

Although the majority of Centaurs are thought to have originated in the scattered disk, with the high-inclination members coming from the Oort cloud, the origin of the high inclination component of trans-Neptunian objects (TNOs) remains uncertain. We report the discovery of a retrograde TNO, which we nickname "Niku", detected by the Pan-STARRS 1 Outer Solar System Survey. Our numerical integrations show that the orbital dynamics of Niku are very similar to that of 2008 KV42 (Drac), with a half-life of ∼500 Myr. Comparing similar high inclination TNOs and Centaurs (q>10 AU, a<100 and="" au="" i="">60∘), we find that these objects exhibit a surprising clustering of ascending node, and occupy a common orbital plane. This orbital configuration has high statistical significance: 3.8-σ. An unknown mechanism is required to explain the observed clustering. This discovery may provide a pathway to investigate a possible reservoir of high-inclination objects.

The Hunt for Planet Nine Finds Multiple Outer Solar System Objects

In the race to discover a proposed ninth planet in our Solar System, Carnegie's Scott Sheppard and Chadwick Trujillo of Northern Arizona University have observed several never-before-seen objects at extreme distances from the Sun in our Solar System. Sheppard and Trujillo have now submitted their latest discoveries to the International Astronomical Union's Minor Planet Center for official designations. A paper about the discoveries has also been accepted to The Astronomical Journal.

The more objects that are found at extreme distances, the better the chance of constraining the location of the ninth planet that Sheppard and Trujillo first predicted to exist far beyond Pluto (itself no longer classified as a planet) in 2014. The placement and orbits of small, so-called extreme trans-Neptunian objects, can help narrow down the size and distance from the Sun of the predicted ninth planet, because that planet's gravity influences the movements of the smaller objects that are far beyond Neptune. The objects are called trans-Neptunian because their orbits around the Sun are greater than Neptune's.

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There are an Estimated 2600 to 3800 Kuiper Belt Objects Beyond 50 AU

The orbital distribution of trans-Neptunian objects beyond 50 au

Authors:

Nesvorny et al

 

Abstract:

 The dynamical structure of the Kuiper belt beyond 50 au is not well understood. Here we report results of a numerical model with long-range, slow and grainy migration of Neptune. The model implies that bodies scattered outward by Neptune to semimajor axes a>50 au often evolve into resonances which subsequently act to raise the perihelion distances of orbits to q>40 au. The implication of the model is that the orbits with 5040 au should cluster near (but not in) the resonances with Neptune (3:1 at a=62.6 au, 4:1 at a=75.9 au, 5:1 at a=88.0 au, etc.). The recent detection of several distant Kuiper Belt Objects (KBOs) near resonances is consistent with this prediction, but it is not yet clear whether the orbits are really non-resonant as our model predicts. We estimate from the model that there should presently be ~1600-2400 bodies at the 3:1 resonance and ~1000-1400 bodies at the 4:1 resonance (for q>40 au and diameters D>100 km). These results favorably compare with the population census of distant KBOs inferred from existing observations.

2015 RR245: a dwarf planet candidate in the 9:2 resonance with Neptune

OSSOS: IV. Discovery of a dwarf planet candidate in the 9:2 resonance

Authors:

Bannister et al

Abstract:

We report the discovery and orbit of a new dwarf planet candidate, 2015 RR245, by the Outer Solar System Origins Survey (OSSOS). 2015 RR245's orbit is eccentric (e=0.586), with a semi-major axis near 82 au, yielding a perihelion distance of 34 au. 2015 RR245 has g−r=0.59±0.11 and absolute magnitude Hr=3.6±0.1; for an assumed albedo of pV=12% the object has a diameter of ∼670 km. Based on astrometric measurements from OSSOS and Pan-STARRS1, we find that 2015 RR245 is securely trapped in the 9:2 mean-motion resonance with Neptune. It is the first TNO identified in this resonance. On hundred-Myr timescales, particles in 2015 RR245-like orbits depart and sometimes return to the resonance, indicating that 2015 RR245 likely forms part of the long-lived metastable population of distant TNOs that drift between resonance sticking and actively scattering via gravitational encounters with Neptune. The discovery of a 9:2 TNO stresses the role of resonances in the long-term evolution of objects in the scattering disk, and reinforces the view that distant resonances are heavily populated in the current Solar System. This object further motivates detailed modelling of the transient sticking population.

Are There Trans Neptunian Objects in the Asteroid Belt?

CAPTURE OF TRANS-NEPTUNIAN PLANETESIMALS IN THE MAIN ASTEROID BELT

Authors:

Vokrouhlický et al

Abstract:

The orbital evolution of the giant planets after nebular gas was eliminated from the Solar System but before the planets reached their final configuration was driven by interactions with a vast sea of leftover planetesimals. Several variants of planetary migration with this kind of system architecture have been proposed. Here, we focus on a highly successful case, which assumes that there were once five planets in the outer Solar System in a stable configuration: Jupiter, Saturn, Uranus, Neptune, and a Neptune-like body. Beyond these planets existed a primordial disk containing thousands of Pluto-sized bodies, ~50 million D > 100 km bodies, and a multitude of smaller bodies. This system eventually went through a dynamical instability that scattered the planetesimals and allowed the planets to encounter one another. The extra Neptune-like body was ejected via a Jupiter encounter, but not before it helped to populate stable niches with disk planetesimals across the Solar System. Here, we investigate how interactions between the fifth giant planet, Jupiter, and disk planetesimals helped to capture disk planetesimals into both the asteroid belt and first-order mean-motion resonances with Jupiter. Using numerical simulations, we find that our model produces the right proportion of P- and D-type asteroids in the inner, central, and outer main belt, while also populating the Hilda and Thule regions in Jupiter's 3/2 and 4/3 resonances. Moreover, the largest observed P/D types in each sub-population are an excellent fit to our captured population results (within uncertainties). The model produces a factor of ~10 overabundance of diameter D > 10 km P/D types in the main belt, but this mismatch can likely be explained by various removal mechanisms (e.g., collision evolution over 4 Gyr, dynamical losses via Yarkovsky thermal forces over 4 Gyr, thermal destruction of the planetesimals en route to the inner solar system). Overall, our instability model provides a more satisfying match to constraints than that of Levison et al., and it provides us with strong supporting evidence that the five giant planet instability model is reasonable. Our results lead us to predict that D-type asteroids found in the near-Earth object population on low delta-V orbits with Earth are the surviving relics from the same source population that now make up the Kuiper Belt, the irregular satellites, and the Jupiter Trojans. The singular Tagish Lake meteorite, a primitive sample unlike other carbonaceous chondrite meteorites, is likely a fragment from a D-type asteroid implanted into the inner main belt. This would effectively make it the first known hand sample with the same composition as Kuiper Belt objects.

Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects

Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects

Authors:

Kaib et al

Abstract:

Recently, Sheppard et al. (2016) presented the discovery of 7 new trans-Neptunian objects with perihelia beyond 40 AU with moderate eccentricities and semimajor axes over 50 AU. Like the handful of previously known bodies on similar orbits, these objects' semimajor axes are just beyond the Kuiper belt edge and clustered around mean motion resonances (MMRs) with Neptune. The objects likely obtained their observed orbits while trapped in a MMR, where the Kozai-Lidov mechanism can raise their perihelia. This mechanism generates a high-perihelion population and also weakens Neptune's dynamical influence over these objects. Here we numerically model the production of this population under a variety of different migration scenarios for Neptune, varying both migration speed and migration smoothness. We find that high-perihelion objects near Neptunian MMRs constrain the nature of Neptune's migration. In particular, the population near the 3:1 MMR (near 62 AU) is especially useful due to its large population and short dynamical evolution timescale. If Neptune reaches its modern orbit after just ~100 Myrs or less of total migration time, we predict that ~90% of the high-perihelion objects near the 3:1 MMR will all have semimajor axes within 1 AU of each other, residing very near the modern resonance's center. On the other hand, if Neptune takes ~300 Myrs of total time to migrate to its final orbit, we expect ~50% of this population to be in dynamically fossilized orbits slightly closer (>~1 AU) to the Sun than the modern resonance location. We highlight 2015 KH162 as a likely member of this fossilized 3:1 population. Under any plausible migration scenario, the vast majority of high-perihelion objects in resonances more distant than the 4:1 MMR (near 76 AU) reach their orbits well after Neptune stops migrating and represent a recently generated, dynamically active population.

More Evidence for Planet Nine in Trans Neptunian Objects

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 Cambridge University 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.

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).

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New Kuiper Belt Objects IDed

Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With Moderate Semi-major Axes and Eccentricities

Authors:

Sheppard et al

Abstract:

We have been conducting a survey for distant solar system objects beyond the Kuiper Belt edge (∼50 AU) with new wide-field cameras on the Subaru 8 meter and CTIO 4 meter telescopes. We are interested in the orbits of objects that are decoupled from the giant planet region in order to understand the structure of the outer solar system, including whether a massive planet exists beyond a few hundred AU as first reported by Trujillo and Sheppard (2014). In addition to discovering extreme trans-Neptunian objects detailed elsewhere, we have found several objects with high perihelia (q>40 AU) that differ from the extreme and inner Oort cloud objects due to their moderate semi-major axes (5020 degrees). These moderate objects likely obtained their unusual orbits through combined interactions with Neptune's mean motion resonances and the Kozai resonance, similar to the origin scenarios for 2004 XR190. We also find the distant 2008 ST291 has likely been modified by the MMR+KR mechanism through the 6:1 Neptune resonance. We discuss these moderately eccentric, distant objects along with some other interesting low inclination outer classical belt objects like 2012 FH84 discovered in our ongoing survey.

Whitmire Returns: Periodicity Rears its Debunked Head With a SuperEarth as Planet X

Periodic mass extinctions and the Planet X model reconsidered

Author:

Whitmire

Abstract:

The 27 Myr periodicity in the fossil extinction record has been confirmed in modern data bases dating back 500 Myr, which is twice the time interval of the original analysis from thirty years ago. The surprising regularity of this period has been used to reject the Nemesis model. A second model based on the sun's vertical galactic oscillations has been challenged on the basis of an inconsistency in period and phasing. The third astronomical model originally proposed to explain the periodicity is the Planet X model in which the period is associated with the perihelion precession of the inclined orbit of a trans-Neptunian planet. Recently, and unrelated to mass extinctions, a trans-Neptunian super-Earth planet has been proposed to explain the observation that the inner Oort cloud objects Sedna and 2012VP113 have perihelia that lie near the ecliptic plane. In this Letter we reconsider the Planet X model in light of the confluence of the modern palaeontological and outer solar system dynamical evidence.

ok.  Gotta say this: periodicity evidence is very week.  Second, YAGUMETS, dude.  The Triassic Extinction and the Permian Extinction were volcano driven!  Not impacts!  The only extinction attributed to impacts is the end cretaceous.  There might be evidence for something in the Carnian, but it needs work.

Updated Taxonomy of Trans-neptunian Objects and Centaurs

Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo

Authors:

Belskaya et al

Abstract:

We present updated classification of 258 trans-neptunian objects (TNOs) and centaurs based on their visible and near-infrared colors. With increasing quality and quantity of color measurements we distinguished again four classes of objects confirming the previous classification into the BB, BR, IR, and RR taxonomic groups. Increasing accuracy of color measurements results in smaller scatter on color–color plots and better separation of classes. Albedos do not have any noticeable impact on the classification except for the separation of a sub-group of the brightest bodies inside the BB group. On the other side, all the BR objects for which albedo estimations are available have dark surfaces, while the IR and RR groups contain objects both with dark and moderate albedos. Analysis of the distribution of the groups with respect to their orbital parameters confirmed previous findings. The BB and RR groups are populated mainly with classical objects having generally high or low orbital inclinations, respectively. Any centaur belongs to the IR group and only one centaur is classified as BB: this is a confirmation of the existence of two separate classes in this population.

Dark Energy Survey Finds Multiple Trans Neptunian Objects

Sometimes when you stare at something long enough, you begin to see things. This is not the case with optical sensors and telescopes. Sure, there is noise from electronics, but it’s random and traceable. Stargazing with a telescope and camera is ideal for staring at the same patches of real estate for very long and repeated periods. This is the method used by the Dark Energy Survey (DES), and with less than one percent of the target area surveyed, astronomers are already discovering previously unknown objects in the outer Solar System.

The Dark Energy Survey is a five year collaborative effort that is observing Supernovae to better understand the structures and expansion of the universe. But in the meantime, transient objects much nearer to home are passing through the fields of view. Trans-Neptunian Objects (TNOs), small icy worlds beyond the planet Neptune, are being discovered. A new scientific paper, released as part of this year’s American Astronomical Society gathering in Seattle, Washington, discusses these newly discovered TNOs. The lead authors are two undergraduate students from Carleton College of Northfield, Minnesota, participating in a University of Michigan program.

The Palomar Sky Survey (POSS-1, POSS-2), the Sloan Digital Sky Survey, and every other sky survey have mapped not just the static, nearly unchanging night sky, but also transient events such as passing asteroids, comets, or novae events. The Dark Energy Survey is looking at the night sky for structures and expansion of the Universe. As part of the five year survey, DES is observing ten select 3 square degree fields for Type 1a supernovae on a weekly basis. As the survey proceeds, they are getting more than anticipated. The survey is revealing more trans-Neptunian objects. Once again, deep sky surveys are revealing more about our local environment – objects in the farther reaches of our Solar System.

link.

The Albedo-color Diversity of Transneptunian Objects

"TNOs Are Cool": A survey of the transneptunian region. XII. The albedo-color diversity of transneptunian objects

Authors:

Lacerda et al

Abstract:

We analyze albedo data obtained using the Herschel Space Observatory that reveal the existence of two distinct types of surface among midsized transneptunian objects. A color-albedo diagram shows two large clusters of objects, one redder and higher albedo and another darker and more neutrally colored. Crucially, all objects located in dynamically stable orbits within the classical Kuiper belt region and beyond are confined to the brighter and redder of the two groups, implying a compositional link. Those objects are believed to have formed further from the Sun than the dark-neutral bodies. This color-albedo separation is evidence for a compositional discontinuity in the young solar system.

The Objects Beyond Neptune

Trans-Neptunian Objects Close to the 2:5 and 1:3 Orbital Resonance With Neptune

Dynamical formation of detached trans-Neptunian objects close to the 2:5 and 1:3 mean motion resonances with Neptune

Authors:

Brasil et al

Abstract:

Through a semi-analytic approach of the Kozai resonance inside an MMR, we show phase diagrams (e,{\omega}) that suggest the possibility of a scattered particle, after being captured in an MMR with Neptune, to become a detached object. We ran several numerical integrations with thousands of particles perturbed by the four major planets, and there are cases with and without Neptune's residual migration. These were developed to check the semi-analytic approach and to better understand the dynamical mechanisms that produce the detached objects close to an MMR. The numerical simulations with and without a residual migration for Neptune stress the importance of a particular resonance mode, which we name the hibernating mode, on the formation of fossilized detached objects close to MMRs. When considering Neptune's residual migration we are able to show the formation of detached orbits. These objects are fossilized and cannot be trapped in the MMRs again. We find a ratio of the number of fossilized objects with moderate perihelion distance (35 less than q less than 40 au) to the number of objects with high perihelion distance (q greater than 40 au) as 3.0/1 for objects close to the 2:5, and 1.7/1 for objects close to the 1:3 resonance. We estimate that the two fossilized population have a total mass between 0.1 and 0.3 Pluto's mass.