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F Roig - One of the best experts on this subject based on the ideXlab platform.
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taxonomy of asteroid families among the jupiter Trojans comparison between spectroscopic data and the sloan digital sky survey colors
Astronomy and Astrophysics, 2008Co-Authors: F Roig, A O Ribeiro, R GilhuttonAbstract:Aims. We present a comparative analysis of the spectral slope and color distributions of Jupiter Trojans, with particular attention to asteroid families. We use a sample of data from the Moving Object Catalog of the Sloan Digital Sky Survey, together with spectra obtained from several surveys. Methods. We extracted a first sample of 349 observations, corresponding to 250 Trojan Asteroids, from the Sloan Digital Sky Survey, and a second sample of 138 spectra, corresponding to 115 Trojans, from the literature. We computed the spectral slopes in the first sample by means of a least-squares fit to a straight line of the fluxes obtained from the Sloan observations, and in the second sample by means of a fit to the rebinned spectra. In both cases the reflectance fluxes/spectra were renormalized to 1 at 6230 A. Results. We found that the distribution of spectral slopes among Trojan Asteroids shows a bimodality. About 2/3 of the objects have reddish slopes compatible with D-type Asteroids, while the remaining bodies show less reddish colors compatible with the P-type and C-type classifications. The members of asteroid families also show a bimodal distribution with a very slight predominance of D-type Asteroids, but the background is clearly dominated by the D-types. The L4 and L5 swarms show different distributions of spectral slopes, and bimodality is only observed in L4. These differences can be attributed to the asteroid families since the background Asteroids show the same slope distributions in both swarms. The analysis of individual families indicates that the families in L5 are taxonomically homogeneous, but in L4 they show a mixture of taxonomic types. We discuss a few scenarios that might help to interpret these results.
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taxonomy of asteroid families among the jupiter Trojans comparison between spectroscopic data and the sloan digital sky survey colors
arXiv: Astrophysics, 2007Co-Authors: F Roig, A O Ribeiro, R GilhuttonAbstract:We present a comparative analysis of the spectral slope and color distributions of Jupiter Trojans, with particular attention to asteroid families. We use a sample of data from the Moving Object Catalogue of the Sloan Digital Sky Survey, together with spectra obtained from several surveys. A first sample of 349 observations, corresponding to 250 Trojan Asteroids, were extracted from the Sloan Digital Sky Survey, and we also extracted from the literature a second sample of 91 spectra, corresponding to 71 Trojans. The spectral slopes were computed by means of a least-squares fit to a straight line of the fluxes obtained from the Sloan observations in the first sample, and of the rebinned spectra in the second sample. In both cases the reflectance fluxes/spectra were renormalized to 1 at 6230 $\textrm{\AA}$. We found that the distribution of spectral slopes among Trojan Asteroids shows a bimodality. About 2/3 of the objects have reddish slopes compatible with D-type Asteroids, while the remaining bodies show less reddish colors compatible with the P-type and C-type classifications. The members of asteroid families also show a bimodal distribution with a very slight predominance of D-type Asteroids, but the background is clearly dominated by the D-types. The L4 and L5 swarms show different distributions of spectral slopes, and bimodality is only observed in L4. These differences can be attributed to the asteroid families since the backgraound Asteroids show the same slope distribtuions in both swarms. The analysis of individual families indicates that the families in L5 are taxonomically homogeneous, but in L4 they show a mixture of taxonomic types. We discuss a few scenarios that might help to interpret these results.
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planetary migration and the effects of mean motion resonances on jupiter s Trojan Asteroids
The Astronomical Journal, 2001Co-Authors: T A Michtchenko, C Beauge, F RoigAbstract:We present results of several numerical simulations of fictitious Trojan Asteroids under different resonant configurations of the outer planets, especially between Jupiter and Saturn. Although the present outer solar system is not locked in mean motion resonances, such commensurabilities may have been temporarily attained in the past if current theories of planetary migration are correct. By studying the evolution of Trojan-like test particles under these conditions, it is possible to obtain information related to the maximum variation of the semimajor axes of the two major Jovian planets, as well as insights on the duration of the migration itself. Results show that the 2S : 1J and 5S : 2J Jupiter-Saturn resonances introduce large instabilities in the Trojan region. In the case of 2S : 1J, a few thousand years are sufficient to expel all particles initially in tadpole orbits. For 5S : 2J, these may survive for up to 106 yr. The 7S : 3J commensurability, on the other hand, is much less disruptive. These results seem to indicate that the observed presence of the Jovian Trojans is compatible with a planetary migration as proposed by Han & Malhotra, in which the orbital distance between Jupiter and Saturn did not vary by more about 1 AU. Larger variations of the semimajor axes seem unlikely.
R S Gomes - One of the best experts on this subject based on the ideXlab platform.
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origin of the orbital architecture of the giant planets of the solar system
Nature, 2005Co-Authors: Kleomenis Tsiganis, Alessandro Morbidelli, R S Gomes, Harold F LevisoAbstract:A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan Asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and Asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Planetary formation theories1,2 suggest that the giant planets formed on circular and coplanar orbits. The eccentricities of Jupiter, Saturn and Uranus, however, reach values of 6 per cent, 9 per cent and 8 per cent, respectively. In addition, the inclinations of the orbital planes of Saturn, Uranus and Neptune take maximum values of ∼2 degrees with respect to the mean orbital plane of Jupiter. Existing models for the excitation of the eccentricity of extrasolar giant planets3,4,5 have not been successfully applied to the Solar System. Here we show that a planetary system with initial quasi-circular, coplanar orbits would have evolved to the current orbital configuration, provided that Jupiter and Saturn crossed their 1:2 orbital resonance. We show that this resonance crossing could have occurred as the giant planets migrated owing to their interaction with a disk of planetesimals6,7. Our model reproduces all the important characteristics of the giant planets' orbits, namely their final semimajor axes, eccentricities and mutual inclinations.
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chaotic capture of jupiter s Trojan Asteroids in the early solar system
Nature, 2005Co-Authors: Alessandro Morbidelli, Kleomenis Tsiganis, Harold F Levison, R S GomesAbstract:A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan Asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and Asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Jupiter's Trojans are Asteroids that follow essentially the same orbit as Jupiter, but lead or trail the planet by an angular distance of ∼60 degrees (co-orbital motion). They are hypothesized to be planetesimals that formed near Jupiter and were captured onto their current orbits while Jupiter was growing1,2, possibly with the help of gas drag3,4,5,6 and/or collisions7. This idea, however, cannot explain some basic properties of the Trojan population, in particular its broad orbital inclination distribution, which ranges up to ∼40 degrees (ref. 8). Here we show that the Trojans could have formed in more distant regions and been subsequently captured into co-orbital motion with Jupiter during the time when the giant planets migrated by removing neighbouring planetesimals9,10,11,12. The capture was possible during a short period of time, just after Jupiter and Saturn crossed their mutual 1:2 resonance, when the dynamics of the Trojan region were completely chaotic. Our simulations of this process satisfactorily reproduce the orbital distribution of the Trojans and their total mass.
Alessandro Morbidelli - One of the best experts on this subject based on the ideXlab platform.
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Observat·orio Nacional, Rio de Janeiro
2016Co-Authors: Harold F Levison, Alessandro Morbidelli, Rodney Gomes, Dana BackmanAbstract:Planets embedded in a planetesimal disk will migrate as a result of angular momentum and energy conservation as the planets scatter the planetesimals that they encounter. A surprising variety of interesting and complex dynamics can arise from this apparently simple process. In this Chapter, we review the basic characteristics of planetesimal-driven migration. We discuss how the structure of a planetary system controls migration. We describe how this type of migration can cause planetary systems to become dynamically unstable and how a massive planetesimal disk can save planets from being ejected from the planetary system during this instability. We examine how the Solar System’s small body reservoirs, particularly the Kuiper belt and Jupiter’s Trojan Asteroids, constrain what happened here. We also review a new model for the early dynamical evolution of the outer Solar System that quantitatively reproduces much of what we see. And nally, we briey discuss how planetesimal driven migration could have affected some of the extra-solar systems that have recently been discovered. 1
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origin of the orbital architecture of the giant planets of the solar system
Nature, 2005Co-Authors: Kleomenis Tsiganis, Alessandro Morbidelli, R S Gomes, Harold F LevisoAbstract:A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan Asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and Asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Planetary formation theories1,2 suggest that the giant planets formed on circular and coplanar orbits. The eccentricities of Jupiter, Saturn and Uranus, however, reach values of 6 per cent, 9 per cent and 8 per cent, respectively. In addition, the inclinations of the orbital planes of Saturn, Uranus and Neptune take maximum values of ∼2 degrees with respect to the mean orbital plane of Jupiter. Existing models for the excitation of the eccentricity of extrasolar giant planets3,4,5 have not been successfully applied to the Solar System. Here we show that a planetary system with initial quasi-circular, coplanar orbits would have evolved to the current orbital configuration, provided that Jupiter and Saturn crossed their 1:2 orbital resonance. We show that this resonance crossing could have occurred as the giant planets migrated owing to their interaction with a disk of planetesimals6,7. Our model reproduces all the important characteristics of the giant planets' orbits, namely their final semimajor axes, eccentricities and mutual inclinations.
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chaotic capture of jupiter s Trojan Asteroids in the early solar system
Nature, 2005Co-Authors: Alessandro Morbidelli, Kleomenis Tsiganis, Harold F Levison, R S GomesAbstract:A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan Asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and Asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Jupiter's Trojans are Asteroids that follow essentially the same orbit as Jupiter, but lead or trail the planet by an angular distance of ∼60 degrees (co-orbital motion). They are hypothesized to be planetesimals that formed near Jupiter and were captured onto their current orbits while Jupiter was growing1,2, possibly with the help of gas drag3,4,5,6 and/or collisions7. This idea, however, cannot explain some basic properties of the Trojan population, in particular its broad orbital inclination distribution, which ranges up to ∼40 degrees (ref. 8). Here we show that the Trojans could have formed in more distant regions and been subsequently captured into co-orbital motion with Jupiter during the time when the giant planets migrated by removing neighbouring planetesimals9,10,11,12. The capture was possible during a short period of time, just after Jupiter and Saturn crossed their mutual 1:2 resonance, when the dynamics of the Trojan region were completely chaotic. Our simulations of this process satisfactorily reproduce the orbital distribution of the Trojans and their total mass.
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Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets
Nature, 2005Co-Authors: Rodney Gomes, Harold F Levison, Kleomenis Tsiganis, Alessandro MorbidelliAbstract:A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan Asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and Asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. The petrology record on the Moon suggests that a cataclysmic spike in the cratering rate occurred ∼700 million years after the planets formed1; this event is known as the Late Heavy Bombardment (LHB). Planetary formation theories cannot naturally account for an intense period of planetesimal bombardment so late in Solar System history2. Several models have been proposed to explain a late impact spike3,4,5,6, but none of them has been set within a self-consistent framework of Solar System evolution. Here we propose that the LHB was triggered by the rapid migration of the giant planets, which occurred after a long quiescent period. During this burst of migration, the planetesimal disk outside the orbits of the planets was destabilized, causing a sudden massive delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, with these objects supplying a significant fraction of the LHB impactors in accordance with recent geochemical evidence7,8. Our model not only naturally explains the LHB, but also reproduces the observational constraints of the outer Solar System9.
David Vokrouhlický - One of the best experts on this subject based on the ideXlab platform.
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searching for Trojan Asteroids in the hd 209458 system space based most photometry and dynamical modeling
The Astrophysical Journal, 2010Co-Authors: Reka Moldovan, J M Matthews, Brett Gladman, W F Bottke, David VokrouhlickýAbstract:We have searched Microvariability and Oscillations of Stars (MOST) satellite photometry obtained in 2004, 2005, and 2007 of the solar-type star HD 209458 for Trojan asteroid swarms dynamically coupled with the system's transiting hot Jupiter HD 209458b. Observations of the presence and nature of Asteroids around other stars would provide unique constraints on migration models of exoplanetary systems. Our results set an upper limit on the optical depth of Trojans in the HD 209458 system that can be used to guide current and future searches of similar systems by upcoming missions. Using cross-correlation methods with artificial signals implanted in the data, we find that our detection limit corresponds to a relative Trojan transit depth of 1 ×10–4, equivalent to ~1 lunar mass of Asteroids, assuming power-law Trojan size distributions similar to Jupiter's Trojans in our solar system. We confirm with dynamical interpretations that some Asteroids could have migrated inward with the planet to its current orbit at 0.045 AU, and that the Yarkovsky effect is ineffective at eliminating objects of >1 m in size. However, using numerical models of collisional evolution we find that, due to high relative speeds in this confined Trojan environment, collisions destroy the vast majority of the Asteroids in <10 Myr. Our modeling indicates that the best candidates to search for exoTrojan swarms in 1:1 mean resonance orbits with hot Jupiters are young systems (ages of about 1 Myr or less). Years of Kepler satellite monitoring of such a system could detect an asteroid swarm with a predicted transit depth of 3 × 10–7.
Julie Ziffer - One of the best experts on this subject based on the ideXlab platform.
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Albedos of Small Jovian Trojans
The Astronomical Journal, 2009Co-Authors: Yanga R. Fernandez, David Jewitt, Julie ZifferAbstract:We present thermal observations of 44 Jovian Trojan Asteroids with diameters D ranging from 5 to 24 km. All objects were observed at a wavelength of 24 μm with the Spitzer Space Telescope. Measurements of the thermal emission and of scattered optical light, mostly from the University of Hawaii 2.2 m Telescope, together allow us to constrain the diameter and geometric albedo of each body. We find that the median R-band albedo of these small Jovian Trojans is about 0.12, much higher than that of large Trojans with D>57 km (0.04). Also the range of albedos among the small Trojans is wider. The small Trojans' higher albedos are also glaringly different from those of cometary nuclei, which match our sample Trojans in diameter, however, they roughly match the spread of albedos among (much larger) Centaurs and trans-Neptunian objects. We attribute the Trojan albedos to an evolutionary effect: the small Trojans are more likely to be collisional fragments and so their surfaces would be younger. A younger surface means less cumulative exposure to the space environment, which suggests that their surfaces would not be as dark as those of the large, primordial Trojans. In support of this hypothesis is a statistically significant correlation of higher albedo with smaller diameter in our sample alone and in a sample that includes the larger Trojans. This correlation of albedo and radius implies that the true size distribution of small Trojans is shallower than the visible magnitude distribution alone would suggest, and that there are approximately half the Trojans with D>1 km than previously estimated.
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Albedos of Small Jovian Trojans
The Astronomical Journal, 2009Co-Authors: Yanga R. Fernandez, David Jewitt, Julie ZifferAbstract:We present thermal observations of 44 Jovian Trojan Asteroids with diameters (D) ranging from 5 to 24 km. All objects were observed at a wavelength of 24 microns with the Spitzer Space Telescope. Measurements of the thermal emission and of scattered optical light, mostly from the University of Hawaii 2.2-meter telescope, together allow us to constrain the diameter and geometric albedo of each body. We find that the median R-band albedo of these small Jovian Trojans is about 0.12, much higher than that of "large" Trojans with D > 57 km (0.04). Also the range of albedos among the small Trojans is wider. We attribute the Trojan albedos to an evolutionary effect: the small Trojans are more likely to be collisional fragments and so their surfaces would be younger. A younger surface means less cumulative exposure to the space environment, which suggests that their surfaces would not be as dark as those of the large, primordial Trojans. In support of this hypothesis is a statistically significant correlation of higher albedo with smaller diameter in our sample alone and in a sample that includes the larger Trojans.
