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Accretional temperature profiles for Saturn’s large moon Titan are used to determine the conditions needed for accretion to avoid global melting as a function of the timing, duration, and nebular conditions of Titan’s accretion. We find that Titan can accrete undifferentiated in a “gas-starved” disk even with modest quantities of ammonia mixed in with its ices. Simulations of impact-induced core formation...
An icy satellite whose interior is composed of a homogeneous ice/rock mixture must avoid melting during its entire history, including during its formation when it was heated by deposition of accretional energy and short-lived radioisotopes. Estimates of the temperature rise associated with radiogenic and accretional heating, coupled with limits on satellite melting can be used to constrain the timing...
Prior models of lunar-forming impacts assume that both the impactor and the target protoearth were not rotating prior to the Moon-forming event. However, planet formation models suggest that such objects would have been rotating rapidly during the late stages of terrestrial accretion. In this paper I explore the effects of pre-impact rotation on impact outcomes through more than 100 hydrodynamical...
Results of about 100 hydrodynamic simulations of potential Moon-forming impacts are presented, focusing on the ''late impact'' scenario in which the lunar forming impact occurs near the very end of Earth's accretion (Canup and Asphaug, 2001, Nature 412, 708-712). A new equation of state is utilized that includes a treatment of molecular vapor (''M-ANEOS''; Melosh, 2000, in: Proc. Lunar Planet. Sci...
We describe a scaling relationship that can be used to characterize the results of numerical smooth particle hydrodynamic (SPH) experiments of potential satellite-forming impacts. The relationship is used to interpret and summarize data from 41 such SPH simulations, all employing an impactor-to-target mass ratio of 3:7, but with a variety of total masses and angular momenta. The results can be utilized...
We perform three-dimensional N-body integrations of the final stages of terrestrial planet formation. We report the results of 10 simulations beginning with 22-50 initial planetary embryos spanning the range 0.5-1.5 AU, each with an initial mass of 0.04-0.13M . Collisions are treated as inelastic mergers. We follow the evolution of each system for 2x10 8 years at which time a few...
An evolutionary model of the G Ring incorporating theoretical results from R. M. Canup and L. W. Esposito (1995,Icarus113, 331-352) yields a complete particle size distribution that is consistent with existing observations. Results from numerical modeling demonstrate that a G Ring origin from the disruption of a 1.5-3 km progenitor satellite can match all known properties of the ring. In addition,...
We present the first published numerical calculations of accretion of an impact-generated protolunar disk into a single large Moon. Our calculations are based on the model developed by R. M. Canup and L. W. Esposito (Icarus113, 331–352, 1995) to describe accretion in the Roche zones around the giant planets. Previous numerical simulations of a large impact event predict the formation of a disk of...
Traditional accretion simulations predict rapid accumulation of ring debris into single satellites, while most theories of ring formation dismiss any accretion within the classical Roche limit. The former contradicts the continued presence of planetary rings, while the latter fails to adequately account for the many small satellites observed within ring systems. The coexistence of rings and small...
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