Effect of Stellar Encounters on Comet Cloud Formation

Higuchi, Arika; Kokubo, Eiichiro

doi:10.1088/0004-6256/150/1/26

Cited by 23 publications

(19 citation statements)

References 27 publications

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“…There have been studies related to the effect of stellar encounters on the solar birth environment and on dynamics of highly eccentric and inclined objects in our solar system (Adams & Laughlin 2001;Kobayashi et al 2005;Adams 2010;BailerJones 2015;Mamajek et al 2015;Jílková et al 2015;Higuchi & Kokubo 2015). In our work, for an initial 100 AU disk and considering an equal-mass perturber, close stellar fly-bys at an encounter distance of ≈100−150 AU would result in a disk the size of the solar system ≈30−50 AU.…”

Section: Discussionmentioning

confidence: 86%

Effects of inclined star-disk encounter on protoplanetary disk size

Bhandare

Breslau

Pfalzner

2016

A&A

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Most, if not all, young stars are initially surrounded by protoplanetary disks. Owing to the preferential formation of stars in stellar clusters, the protoplanetary disks around these stars may potentially be affected by the cluster environment. Various works have investigated the influence of stellar fly-bys on disks, although many of them consider only the effects due to parabolic, coplanar encounters often for equal-mass stars, which is only a very special case. We perform numerical simulations to study the fate of protoplanetary disks after the impact of parabolic star-disk encounter for the less investigated case of inclined up to coplanar, retrograde encounters, which is a much more common case. Here, we concentrate on the disk size after such encounters because this limits the size of the potentially forming planetary systems. In addition, with the possibilities that ALMA offers, now a direct comparison to observations is possible. Covering a wide range of periastron distances and mass ratios between the mass of the perturber and central star, we find that despite the prograde, coplanar encounters having the strongest effect on the disk size, inclined and even the least destructive retrograde encounters mostly also have a considerable effect, especially for close periastron passages. Interestingly, we find a nearly linear dependence of the disk size on the orbital inclination for the prograde encounters, but not for the retrograde case. We also determine the final orbital parameters of the particles in the disk such as eccentricities, inclinations, and semi-major axes. Using this information the presented study can be used to describe the fate of disks and also that of planetary systems after inclined encounters.

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Section: Discussionmentioning

confidence: 86%

Effects of inclined star-disk encounter on protoplanetary disk size

Bhandare

Breslau

Pfalzner

2016

A&A

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“…The dynamics driven by ε G V HG V taken alone has been studied by many authors. The solutions can actually be expressed analytically in terms of elliptic integrals (see Breiter & Ratajczak 2005, Higuchi et al 2007, Higuchi & Kokubo 2015. The quantity…”

Section: Galactic Regimementioning

confidence: 99%

Chaos in the inert Oort cloud

Saillenfest

Fouchard

Itô

et al. 2019

A&A

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Context. Distant trans-Neptunian objects are subject to planetary perturbations and galactic tides. The former decrease with the distance, while the latter increase. In the intermediate regime where they have the same order of magnitude (the 'inert Oort cloud'), both are weak, resulting in very long evolution timescales. To date, three observed objects can be considered to belong to this category. Aims. We aim to provide a clear understanding of where this transition occurs, and to characterise the long-term dynamics of small bodies in the intermediate regime: relevant resonances, chaotic zones (if any), and timescales at play. Methods. The different regimes are explored analytically and numerically. We also monitored the behaviour of swarms of particles during 4.5 Gyrs in order to identify which of the dynamical features are discernible in a realistic amount of time.Results. There exists a tilted equilibrium plane (Laplace plane) about which orbits precess. The dynamics is integrable in the low and high semi-major axis regimes, but mostly chaotic in between. From about 800 to 1100 astronomical units (au), the chaos covers almost all the eccentricity range. The diffusion timescales are large, but not to the point of being indiscernible in a 4.5 Gyrs duration: the perihelion distance can actually vary from tens to hundreds of au. Orbital variations are damped near the ecliptic (where previous studies focussed), but favoured in specific ranges of inclination corresponding to well-defined resonances. Moreover, starting from uniform distributions, the orbital angles cluster after 4.5 Gyrs for semi-major axes larger than 500 au, because of a very slow differential precession. Conclusions. Even if it is characterised by very long timescales, the inert Oort cloud mostly features chaotic regions; it is therefore much less inert than it appears. Orbits can be considered inert over 4.5 Gyrs only in small portions of the space of orbital elements, which include (90377) Sedna and 2012VP113. Effects of the galactic tides are discernible down to semi-major axes of about 500 au. We advocate including the galactic tides in simulations of distant trans-Neptunian objects, especially when studying the formation of detached bodies or the clustering of orbital elements.

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“…We expect the concentrations even when we consider the effect of passing stars. Perturbations from passing stars change the conserved quantities and may break the relation between q, B, and L more or less; however, it takes a much longer time to change the eccentricity vector (i.e., L and B) than to change i (Higuchi & Kokubo 2015). Therefore, we suggest that observers, including the space mission Comet Interceptor, focus on the ecliptic plane and/or the empty ecliptic plane to find dynamically new comets.…”

Section: Summary and Discussionmentioning

confidence: 90%

Anisotropy of Long-period Comets Explained by Their Formation Process

Higuchi

2020

Preprint

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Long-period comets coming from the Oort cloud are thought to be planetesimals formed in the planetary region on the ecliptic plane. We have investigated the orbital evolution of these bodies due to the Galactic tide. We extended Higuchi et al. (2007) and derived the analytical solutions to the Galactic longitude and latitude of the direction of aphelion, L and B. Using the analytical solutions, we show that the ratio of the periods of the evolution of L and B is very close to either 2 or ∞ for initial eccentricities e i ≃ 1, as is true for the Oort cloud comets. From the relation between L and B, we predict that Oort cloud comets returning to the planetary region are concentrated on the ecliptic plane and a second plane, which we call the "empty ecliptic." This consists in a rotation of the ecliptic around the Galactic pole by 180 • . Our numerical integrations confirm that the radial component of the Galactic tide, which is neglected in the derivation of the analytical solutions, is not strong enough to break the relation between L and B derived analytically. Brief examination of observational data shows that there are concentrations near both the ecliptic and the empty ecliptic. We also show that the anomalies of the distribution of B of long-period comets mentioned by several authors are explained by the concentrations on the two planes more consistently than by previous explanations.

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Effect of Stellar Encounters on Comet Cloud Formation

Cited by 23 publications

References 27 publications

Effects of inclined star-disk encounter on protoplanetary disk size

Effects of inclined star-disk encounter on protoplanetary disk size

Chaos in the inert Oort cloud

Anisotropy of Long-period Comets Explained by Their Formation Process

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