1,720,995 research outputs found
Origin of slow-rotating minor bodies by tidal decoupling of binary pairs
Get PDFIn this paper, we show that the decoupling of binary pairs by tidal interaction and Kozai oscillations acting together can generate single objects in a slow-rotation-rate state. This mechanism has the merit of not being strongly dependent on the size or shape of the objects. The key parameter leading the process is ω/n, the ratio between the rotation rate and the orbital mean motion of the binary, which must be > 1. The proposed mechanism could also operate in other populations of minor bodies.Fil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Departamento de Ciencias Exactas y Naturales; Argentin
Flipping the orbital planes of primordial trans neptunian binaries by close encounters with Neptune during the planetary instability migration phase of the outer solar system
No full textThe distribution of inclinations of the mutual orbits of trans-Neptunian binaries contains valuable information about the formation of these binaries. The inclinations measured so far show a clear preference of orbital motion in the same sense as the orbits around the Sun. This fact strongly favours binary formation by the gravitational collapse of nebular clumps of small solid particles. A few binaries, however, are orbiting with a retrograde motion, challenging an origin by this mechanism. Here we show that an implanted population of binaries, formed by gravitational cloud collapse in direct orbits, flipped their orbital planes during close encounters with Neptune. The cloud collapse formation mechanism is therefore the most plausible way to form trans-Neptunian binaries in the innermost part of the outer Solar system, which were then implanted in the Kuiper belt during the planetary instability phase.Fil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Departamento de Ciencias Exactas y Naturales; Argentin
On the dynamical evolution and end states of binary centaurs
Get PDFIn this paper, we perform a numerical integration of 666 fictitious binary Centaurs coming from the trans Neptunian space. Our population is restricted to tight binaries whose components have sizes between 30 and 100 km. We included the dynamical perturbations from the giant planets, Kozai Cycles induced by the Sun and tidal friction on the orbits of the binaries. We found that most binaries are disrupted during one of the close planetary encounters, making the mean lifetime of binary Centaurs much shorter than the one of single Centaurs. Nearly 10 per cent of the binaries reach a very tight circular orbit, arguing in favour of the existence of a non-negligible population of contact Centaurs. Another 10 per cent survive as a binary during their lifetime as Centaur. Our simulations favour the existence of a small population of very tight binary Centaurs.Fil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica la Plata; Argentin
Dynamical evolution of a fictitious population of binary Neptune Trojans
Get PDFWe present numerical simulations of the evolution of a synthetic population of Binary Neptune Trojans, under the influence of the solar perturbations and tidal friction (the so-called Kozai cycles and tidal friction evolution). Our model includes the dynamical influence of the four giant planets on the heliocentric orbit of the binary centre of mass. In this paper, we explore the evolution of initially tight binaries around the Neptune L4 Lagrange point. We found that the variation of the heliocentric orbital elements due to the libration around the Lagrange point introduces significant changes in the orbital evolution of the binaries. Collisional processes would not play a significant role in the dynamical evolution of Neptune Trojans. After 4.5×109 yr of evolution, ~ 50 per cent of the synthetic systems end up separated as single objects, most of them with slow diurnal rotation rate. The final orbital distribution of the surviving binary systems is statistically similar to the one found for Kuiper Belt Binaries when collisional evolution is not included in the model. Systems composed by a primary and a small satellite are more fragile than the ones composed by components of similar sizes.Fil: Brunini, Adrian. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
The origin of an overpopulation of contact binary plutinos
No full textIn the trans-Neptunian region, 10-25% of binary objects are contact binaries. However, the amplitude of the light curves of a sample of Plutinos indicates that there this fraction could reach 50 % or even more. This remarkable difference cannot be explained by the single action of the Kozai cycles and tidal friction (KCTF), nor it can be assumed that it is due to a formation mechanism different from the one that gave rise to the binaries of the other hot populations. In this work we present numerical simulations showing that a super abundance of contact binaries occurs as a natural consequence of the coupling between the dynamical evolution of the mutual orbit of the binaries subject to the action of KCTF, and the variation of the heliocentric orbit of the binary centre of mass due to the perturbations of the giant planets. This same mechanism affects the other populations, but to a lesser extent, because the variations of the heliocentric orbits are much smaller for them than for objects that are within the 3:2 mean motion resonance with Neptune. This mechanism also increases the fraction of tight binaries in the Plutino population, where it could reach ∼ 30%.Fil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral; Argentin
The effect of the giant planets on the dynamical evolution of the mutual orbits of trans-Neptunian binaries
Get PDFThe action of tidal friction, coupled with the Kozai cycles, dras-tically changed the original orbits of trans-Neptunian binaries (TNBs). Thedynamics of the Kozai mechanism is driven by the solar torque on the mu-tual orbit, so that the orientation of the latter relative to the heliocentricorbital plane plays a fundamental role in this process, both in the magnitudeand in the characteristic of the cycles. In this way, any eect that makes thisrelative orientation vary may be relevant in the dynamics of the process.In this paper, we will focus on the eect that the perturbations of the gi-ant planets on the heliocentric orbit of TNBs have on the dynamics of theKozai cycles and tidal friction. For this task, we have performed numericalsimulations of the evolution of a synthetic population of TNBs subject toKozai cycles and tidal friction, and adding planetary perturbation on theirheliocentric orbits. We found that in a non-negligible fraction of cases ( 25%), this additional perturbation produces substantial changes in the orbitalevolution. The slow precession of the heliocentric orbit and the variation ofits inclination can make the dynamical evolution of the mutual orbits veryirregular, completely changing the morphology of the Kozai cycles. Whenthese variations are coupled to tidal friction, the life-time of the TNBs canchange substantially.Fil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia; Argentin
The Buildup of a Tightly Bound Comet Cloud around an Early Sun Immersed in a Dense Galactic Environment: Numerical Experiments
Get PDFWe simulate numerically the buildup of a comet reservoir around the early Sun assumed to be still immersed in the placental molecular gas that gave birth to it, and to be gravitationally bound to other young stars formed out of the same gas. We show that under certain reasonable assumptions about the early galactic environment of the Sun, an inner core of the Oort cloud of radius from a few 102 AU to a few 103 AU forms on a time scale of a few million year. Jupiter and Saturn are the main scatterers of matter to this inner core, though a significant fraction of the matter scattered by these two planets (perhaps more than 50%) might originally come from the accretion zones of Uranus and Neptune. If the formation process of the jovian planets left unaccreted an amount of solid material of the same order of their own planet masses (the rock-icy cores for the cases of Jupiter and Saturn), then a few M⊕ of the scattered solid material might have been trapped in the Oort reservoir, most of it in the inner core.Fil: Fernández, Julio A.. Facultad de Ciencias. Departamento de Astronomía; UruguayFil: Brunini, Adrian. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin
On oligarchic growth of planets in protoplanetary disks
Get PDFIn this paper we present a new semianalytical model of oligarchic growth of planets considering a distribution of planetesimal sizes, fragmentation of planetesimals in mutual collisions, sublimation of ices through the snow line, random velocities out of equilibrium and merging of planetary embryos. We show that the presence of several planetary embryos growing simultaneously at different locations in the protoplanetary disk affects the whole accretion history, specially for the innermost planets. The results presented here clearly indicate the relevance of considering a distribution of planetesimal sizes. Fragmentation occurring during planetesimal–planetesimal collisions represent only a marginal effect in shaping the surface density of solid material in the protoplanetary disc.Fil: Brunini, Adrian. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Benvenuto, Omar Gustavo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentin
The existence of a planet beyond 50 au and the orbital distribution of the classical Edgeworth–Kuiper-Belt objects
Get PDFWe study the effects of a Mars-like planetoid with a semimajor axis at about ∼60 AU orbiting embedded in the primordial Edgeworth–Kuiper belt (EKB). The origin of such an object can be explained in the framework of our current understanding of the origin of the outer Solar System, and a scenario for the orbital transport mechanism to its present location is given. The existence of such an object would produce a gap in the EKB distribution with an edge at about 50 AU, which seems to be in agreement with the most recent observations. No object at low eccentricity with semimajor axis beyond 50 AU has been detected so far, even though the present observing capabilities would allow an eventual detection (B. Gladman et al. 1998, Astron. J. 116, 2042–2054; D. Jewitt et al. 1998, Astron. J. 115, 2125–2135; E. I. Chiang and M. E. Brown 1999, Astron. J. 118, 1411–1422; R. L. Allen et al. 2000, Astrophys. J. 549, 241–244; C. A. Trujillo et al. 2001, Astron. J. 122, 457–473; B. Gladman et al. 2001, Astron. J. 122, 1051–1066; C. A. Trujillo and M. E. Brown 2001, Astrophys. J. 554, 95–98). Finally, ranges for the magnitude and proper motion of the proposed object are given.Fil: Brunini, Adrian. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Melita, Mario Daniel. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. City University of London; Reino Unid
Methods for computing giant planet formation and evolution
Get PDFWe present a numerical code for computing all stages of the formation and evolution of giant planets in the framework of the core instability mechanism. This code is a non-trivial adaption of the stellar binary evolution code and is based on a standard Henyey technique. To investigate the performance of this code we applied it to the computation of the formation and evolution of a Jupiter mass object from a half Earth core mass to ages in excess of the age of the Universe. We also present a new smoothed linear interpolation algorithm devised especially for the purpose of circumventing some problems found when some physical data (e.g. opacities, equation of state, etc.) are introduced into an implicit algorithm like the one employed in this work.Fil: Benvenuto, Omar Gustavo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Pontificia Universidad Católica de Chile; ChileFil: Brunini, Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin
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