The Extreme Kuiper Belt Binary 2001 QW
            <sub>322</sub>

Petit, Jean-Marc; Kavelaars, J. J.; Gladman, Brett; Margot, Jean-Luc; Nicholson, P. D.; Jones, Lynne; Parker, J. W.; Ashby, M. L. N.; Bagatín, Adriano Campo; Benavídez, Paula Gabriela; Coffey, J.; Rousselot, P.; Mousis, O.; Taylor, Patrick A.

doi:10.1126/science.1163148

Cited by 49 publications

(58 citation statements)

References 10 publications

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“…The black curve is obtained after thermal processing of bodies with 65% ice formed with v coll = v esc /2. Measured densities for dynamically cold classical disk objects (black, gray) are taken from Petit et al (2008), Vilenius et al (2012Vilenius et al ( , 2014, and Carry (2012) based on Grundy et al (2009Grundy et al ( , 2013. Densities for dynamically hot classical disk objects, SD objects, and Centaurs (red) are taken from Blum & Wurm 2008) can be added to the gravitational pressure.…”

Section: The Cold Classical Ekbmentioning

confidence: 99%

“…The targets in black were observed with Herschel by Vilenius et al (2012Vilenius et al ( , 2014 and have radiometrically determined sizes and geometric albedos (except 2001 QW 322 for which Petit et al 2008 assumed p V = 0.16). For the targets in gray Grundy et al (2009Grundy et al ( , 2013 assumed ranges for ρ bulk and p V to constrain diameters.…”

Section: The Cold Classical Ekbmentioning

confidence: 99%

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The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Davidsson

Sierks

Güttler

et al. 2016

A&A

187

162

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Context. We investigate the formation and evolution of comet nuclei and other trans-Neptunian objects (TNOs) in the solar nebula and primordial disk prior to the giant planet orbit instability foreseen by the Nice model. Aims. Our goal is to determine whether most observed comet nuclei are primordial rubble-pile survivors that formed in the solar nebula and young primordial disk or collisional rubble piles formed later in the aftermath of catastrophic disruptions of larger parent bodies. We also propose a concurrent comet and TNO formation scenario that is consistent with observations. Methods. We used observations of comet 67P/Churyumov-Gerasimenko by the ESA Rosetta spacecraft, particularly by the OSIRIS camera system, combined with data from the NASA Stardust sample-return mission to comet 81P/Wild 2 and from meteoritics; we also used existing observations from ground or from spacecraft of irregular satellites of the giant planets, Centaurs, and TNOs. We performed modeling of thermophysics, hydrostatics, orbit evolution, and collision physics. Results. We find that thermal processing due to short-lived radionuclides, combined with collisional processing during accretion in the primordial disk, creates a population of medium-sized bodies that are comparably dense, compacted, strong, heavily depleted in supervolatiles like CO and CO 2 ; they contain little to no amorphous water ice, and have experienced extensive metasomatism and aqueous alteration due to liquid water. Irregular satellites Phoebe and Himalia are potential representatives of this population. Collisional rubble piles inherit these properties from their parents. Contrarily, comet nuclei have low density, high porosity, weak strength, are rich in supervolatiles, may contain amorphous water ice, and do not display convincing evidence of in situ metasomatism or aqueous alteration. We outline a comet formation scenario that starts in the solar nebula and ends in the primordial disk, that reproduces these observed properties, and additionally explains the presence of extensive layering on 67P/Churyumov-Gerasimenko (and on 9P/Tempel 1 observed by Deep Impact), its bi-lobed shape, the extremely slow growth of comet nuclei as evidenced by recent radiometric dating, and the low collision probability that allows primordial nuclei to survive the age of the solar system. Conclusions. We conclude that observed comet nuclei are primordial rubble piles, and not collisional rubble piles. We argue that TNOs formed as a result of streaming instabilities at sizes below ∼400 km and that ∼350 of these grew slowly in a low-mass primordial disk to the size of Triton, Pluto, and Eris, causing little viscous stirring during growth. We thus propose a dynamically cold primordial disk, which prevented mediumsized TNOs from breaking into collisional rubble piles and allowed the survival of primordial rubble-pile comets. We argue that comets formed by hierarchical agglomeration out of material that remained after TNO formation, and that this slow growth was a necessity...

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Section: The Cold Classical Ekbmentioning

confidence: 99%

Section: The Cold Classical Ekbmentioning

confidence: 99%

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Davidsson

Sierks

Güttler

et al. 2016

A&A

187

162

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“…For example, according to Goldreich et al (2002), collisionless gravitational interactions are more efficient in forming the observed, widely separated binaries in the primordial KB than (3). Also, model (4) leads to binary eccentricities e 0.8 and very large semimajor axes, while observations of binary KBOs indicate moderate eccentricities and semimajor axes that are only a few percent of the Hill radius (Noll et al 2008a;Grundy et al 2009), except for 1998 WW 31 with e = 0.82 (Veillet et al 2002) and 2001 QW 322 with a = 120,000 km (Petit et al 2008). Schlichting & Sari (2008a) estimated that chaotic capture in (5) should be less common than direct capture in (1) or (2).…”

Section: Binary Formation In Hierarchical Coagulationmentioning

confidence: 99%

Formation of Kuiper Belt Binaries by Gravitational Collapse

Nesvorný¹,

Youdin²,

Richardson³

2010

The Astronomical Journal

227

324

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A large fraction of ∼100 km class low-inclination objects in the classical Kuiper Belt (KB) are binaries with comparable masses and a wide separation of components. A favored model for their formation is that they were captured during the coagulation growth of bodies in the early KB. However, recent studies have suggested that large, 100 km objects can rapidly form in the protoplanetary disks when swarms of locally concentrated solids collapse under their own gravity. Here, we examine the possibility that KB binaries formed during gravitational collapse when the excess of angular momentum prevented the agglomeration of available mass into a solitary object. We find that this new mechanism provides a robust path toward the formation of KB binaries with observed properties, and can explain wide systems such as 2001 QW 322 and multiples such as (47171) 1999 TC 36 . Notably, the gravitational collapse is capable of producing ∼100% binary fraction for a wide range of the swarm's initial angular momentum values. The binary components have similar masses (∼80% have a secondary-over-primary radius ratio >0.7) and their separation ranges from ∼1000 to ∼100,000 km. The binary orbits have eccentricities from e = 0 to ∼1, with the majority having e < 0.6. The binary orbit inclinations with respect to the initial angular momentum of the swarm range from i = 0 to ∼90• , with most cases having i < 50• . The total binary mass represents a characteristic fraction of the collapsing swarm's total initial mass, M tot , suggesting M tot equivalent to that of a radius ∼100-250 km compact object. Our binary formation mechanism also implies that the primary and secondary components in each binary pair should have identical bulk composition, which is consistent with the current photometric data. We discuss the applicability of our results to the Pluto-Charon, Orcus-Vanth, (617) Patroclus-Menoetius, and (90) Antiope binary systems.

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“…For example, typical high-eccentricity BMPs produced in some scenarios such as the expected e > 0.8 in the exchange scenario of Funato et al (2004), or 0.2 e 0.8 in the chaos assisted capture scenario (Lee et al 2007), could be observed with very low eccentricities, either due to the random phase in which they are observed during their Kozai cycle or due to their KCTF evolution which would have circularized their orbit (e.g., Figure 2). Recently, (and after the initial presentation of this manuscript), Petit et al (2008) have reported on the peculiar orbit of the Kuiper Belt binary 2001 QW 322 , with very large SMA but relatively small eccentricity. Such orbit is difficult to explain through previously suggested BMPs formation scenarios, since a binary with such wide SMA is likely to be produced through the exchange scenario, which would typically produce a highly eccentric binary (Funato et al 2004).…”

Section: Kctf Observational Signature and Bmps Formations Scenariomentioning

confidence: 99%

Kozai Cycles, Tidal Friction, and the Dynamical Evolution of Binary Minor Planets

Perets

Naoz

2009

ApJ

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In recent years, many binary minor planets (BMPs) have been discovered in the solar system. Many models have been suggested for their formation, but these encounter difficulties explaining their observed characteristics. Here, we show that secular perturbations by the Sun (Kozai mechanism) fundamentally change the evolution and the initial distribution of BMPs predicted by such models and lead to unique observational signatures. The Kozai mechanism can lead to a large periodic oscillations in the eccentricity and inclination of highly inclined BMP orbits, where we predict such effects to be observable with current accuracy within a few years (e.g., for the binary asteroid Huenna). In addition, the combined effects of the Kozai mechanism and tidal friction (KCTF) drives BMPs into short-period circular orbits. We predict a specific inclination-dependent distribution of the separation and eccentricity of BMPs, due to these effects, including a zone of avoidance at the highest inclinations. Specifically, the Kozai evolution could explain the recently observed peculiar orbit of the Kuiper Belt binary 2001 QW 322 . Additionally, the KCTF process could lead to BMPs coalescence and serve as an important route for the formation of irregular shaped single minor planets with large axial tilts.

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The Extreme Kuiper Belt Binary 2001 QW ₃₂₂

Cited by 49 publications

References 10 publications

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Formation of Kuiper Belt Binaries by Gravitational Collapse

Kozai Cycles, Tidal Friction, and the Dynamical Evolution of Binary Minor Planets

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The Extreme Kuiper Belt Binary 2001 QW 322

Cited by 49 publications

References 10 publications

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Formation of Kuiper Belt Binaries by Gravitational Collapse

Kozai Cycles, Tidal Friction, and the Dynamical Evolution of Binary Minor Planets

Contact Info

Product

Resources

About

The Extreme Kuiper Belt Binary 2001 QW ₃₂₂