Bulk density of asteroid 243 Ida from the orbit of its satellite Dactyl

Belton, M. J. S.; Chapman, C. R.; Thomas, P. C.; Davies, Merton E.; Greenberg, R.; Klaasen, K. P.; Byrnes, Dennis V.; D’Amario, Louis A.; Synnott, S. P.; Johnson, T. V.; McEwen, A. S.; Merline, W. J.; Davis, Donald R.; Petit, J. M.; Storrs, A. D.; Veverka, J.; Zellner, B.

doi:10.1038/374785a0

Cited by 120 publications

(41 citation statements)

References 14 publications

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“…Moreover, a density ρ i = 2.7 g cm −3 is assumed for the impactors, which is consistent with the densities of several S-type asteroids (e.g. Belton et al 1995;Veverka et al 2000). On the other hand, the impactor velocity v i is given by Figure 4 shows the total number of craters on Ceres and Vesta produced by main belt asteroids as a function of crater diameter obtained using a pseudo-time of 9.5 Gyr.…”

Section: Cratering On Ceres and Vestamentioning

confidence: 79%

Impactor flux and cratering on Ceres and Vesta: implications for the early solar system

Elía

Sisto

2011

A&A

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Context. The forthcoming arrival of the NASA's Dawn spacecraft to Ceres and Vesta means that these unexplored worlds in the asteroid main belt are targets of several studies. Aims. We study the impactor flux and cratering on Ceres and Vesta caused by the collisional and dynamical evolution of the asteroid main belt. Methods. We develop a statistical code based on a well-tested model for the simultaneous evolution of the main belt and NEA size distributions. This code includes catastrophic collisions and noncollisional removal processes such as the Yarkovsky effect and the orbital resonances. It is worth noting that the model assumes that the dynamical depletion of the early main belt was very strong, and owing to that, most main belt comminution occurred when its dynamical structure was similar to the present one. Results. Our results indicate that the number of D > 1 km main belt asteroids striking Ceres and Vesta over the solar system history are approximately 4600 and 1100, respectively. Moreover, the largest main belt asteroids expected to have impacted Ceres and Vesta had a diameter of 71.7 km for Ceres and 21.1 km for Vesta. As for the cratering, our simulations show that the surfaces of Ceres and Vesta present a wide variety of craters with different sizes. In fact, the number of D > 0.1 km craters on Ceres is ∼3.4 × 10 8 and 6.2 × 10 7 on Vesta. Moreover, the number of craters with D > 100 km are 47 on Ceres and 8 on Vesta. On the other hand, our study indicates that the D = 460 km crater observed on Vesta had to be formed by the impact of a D ∼ 66.2 km projectile, which has a probability of occur of ∼30% over the solar system history. Conclusions. If significant discrepancies between our results about the cratering on Ceres and Vesta and data obtained from the Dawn Mission were found, they should be linked to a higher degree of collisional evolution during the early main belt and/or the existence of the late heavy bombardment. An increase in the collisional activity in the early phase may be provided for an initial configuration of the giant planets consistent with, for example, the Nice model. From this, the Dawn Mission would be able to give us clues about the initial configuration of the early solar system and its subsequent dynamical evolution.

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Section: Cratering On Ceres and Vestamentioning

confidence: 79%

Impactor flux and cratering on Ceres and Vesta: implications for the early solar system

Elía

Sisto

2011

A&A

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“…In 1993, the Galileo spacecraft discovered the first binary asteroid, (243) Ida, a 30km diameter S-type asteroid with a small satellite named Dactyl , Chapman et al 1995. It is unclear whether or not Ida should be considered as a rubble pile asteroid (Britt et al 2002), meaning that its internal structure is defined as a weak aggregate of diverse size components held together by gravity rather than material strength.…”

Section: Non Laosa Bodies Incorporated In the Studymentioning

confidence: 99%

Angular momentum of binary asteroids: Implications for their possible origin

Descamps

Marchis

2008

Icarus

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We describe in this work a thorough study of the physical and orbital characteristics of extensively observed main-belt and Trojan binaries, mainly taken from the LAOSA (Large Adaptive Optics Survey of Asteroids, Marchis et al., 2006c) database, along with a selection of bifurcated objects. Dimensionless quantities, such as the specific angular momentum and the scaled primary spin rate, are computed and discussed for each system. They suggest that these asteroidal systems might be the outcome of rotational fission or mass shedding of a parent body presumably subjected to an external torque.One of the most striking features of separated binaries composed of a large primary (R p > 100 km) with a much smaller secondary (R s < 20 km) is that they all have total angular momentum of ~0.27. This value is quite close to the Maclaurin-Jacobi bifurcation (0.308) of a spinning fluid body. Alternatively, contact binaries and tidally locked double asteroids, made of components of similar size, have an angular momentum larger than 0.48. They compare successfully with the fission equilibrium sequence of a rotating fluid mass. In conclusion, we find that total angular momentum is a useful proxy to assess the internal structure of such systems.

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“…The existence and importance of binary asteroids in smallbody populations has only been realized in the last decade, after the first unambiguous detection of a satellite around main-belt asteroid 243 Ida by the Galileo spacecraft (Belton et al 1995;Chapman et al 1995). It is now evident that binaries exist in the main-belt asteroids, the near-Earth asteroids, and the Kuiper Belt (see review by Richardson & Walsh 2006 and references therein).…”

Section: Introductionmentioning

confidence: 99%

Fraction of Contact Binary Trojan Asteroids

2007

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We present the results of an optical light-curve survey of 114 Jovian Trojan asteroids conducted to determine the fraction of contact binaries. Sparse sampling was used to assess the photometric range of the asteroids, and those showing the largest ranges were targeted for detailed follow-up observations. This survey led to the discovery of two Trojan asteroids, (17365) and (29314), displaying large light-curve ranges ($1 mag) and long rotation periods (<2 rotations day À1 ) consistent with a contact binary nature. The optical light curves of both asteroids are well matched by Roche binary equilibrium models. Using these binary models, we find low densities of $600 and 800 kg m À3 , suggestive of porous interiors. The fraction of contact binaries is estimated to be between 6% and 10%, comparable to the fraction in the Kuiper Belt. The total binary fraction in the Trojan clouds (including both wide and close pairs) must be higher.

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Bulk density of asteroid 243 Ida from the orbit of its satellite Dactyl

Cited by 120 publications

References 14 publications

Impactor flux and cratering on Ceres and Vesta: implications for the early solar system

Impactor flux and cratering on Ceres and Vesta: implications for the early solar system

Angular momentum of binary asteroids: Implications for their possible origin

Fraction of Contact Binary Trojan Asteroids

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