Modeling Kuiper belt objects Charon, Orcus and Salacia by means of a new equation of state for porous icy bodies

Core cracking and hydrothermal circulation can profoundly affect Ceres' geophysical evolution

“…First, the bulk density of Orcus is only 1530 kg m −3 , implying a rock/ice mass ratio of 3 (with their chosen densities), twice as low as that we derive for Ceres (6.25). Second, the surface temperature of Orcus is only 41 K, assuming the albedo value used by Malamud and Prialnik []. Third, 26 Al heating is likely negligible at the accretion timescales of the Kuiper belt, of order 10 7 years [ Kenyon and Bromley , ].…”

“…Third, 26 Al heating is likely negligible at the accretion timescales of the Kuiper belt, of order 10 7 years [ Kenyon and Bromley , ]. Finally, silicate‐ice differentiation is very gradual in the models of Malamud and Prialnik [], proceeding as the diffusion of ice and volatiles through a rock matrix. In the present code, differentiation occurs when the temperature of a given layer exceeds a threshold; every layer below is rearranged instantaneously into a core and mantle.…”

“…This model is further discussed below. Finally, time‐evolution models developed by Malamud and Prialnik [] and applied to Enceladus, Mimas, and Kuiper belt objects include the rock swelling and heating effects due to serpentinization, the flow of water liquid and vapor, and a detailed treatment of rock and ice porosity by means of equations of state. These models therefore offer an opportunity for comparison with those presented here.…”

“…We then explain how this model is incorporated as a cracking subroutine into the thermal evolution code of Desch et al [], along with the inclusion of silicate hydration and dehydration, and hydrothermal circulation in the porous layer. The level of detail in the resulting code is similar to that of Malamud and Prialnik [], albeit with a different approach in the treatment of differentiation, porosity, and hydrothermal heat transfer. We apply the model to Ceres and investigate the influence of fracturing and physical water‐rock processes on its evolution.…”

The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë

“…The largest few are planet-sized bodies such as Pluto, Eris, and Makemake, massive enough to retain atmospheres in vapor pressure equilibrium with volatile surface ices (e.g., Elliot et al, 1989;Schaller and Brown, 2007). Numerous slightly smaller TNOs are large enough to relax into spherical shapes, and could have had some degree of geological activity in the past, or even still be active today (e.g., Desch et al, 2009;Malamud and Prialnik, 2015). The scope for comparative planetological studies of these bodies is tremendous, since they come in a range of sizes, occupy a variety of heliocentric orbits, and likely accreted at different heliocentric distances within the protoplanetary nebula, drawing on chemically distinct compositional reservoirs of solid materials.…”