Hydrogen Eos at Megabar Pressures and the Search for Jupiter’s Core |
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| Authors: | William B Hubbard |
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| Institution: | (1) Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ, USA |
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| Abstract: | The interior structure of Jupiter serves as a benchmark for an entire astrophysical class of liquid–metallic hydrogen-rich
objects with masses ranging from ~0.1M
J to ~80M
J (1M
J = Jupiter mass = 1.9e30 g), comprising hydrogen-rich giant planets (mass < 13M
J) and brown dwarfs (mass > 13M
J but ~ < 80M
J), the so-called substellar objects (SSOs). Formation of giant planets may involve nucleated collapse of nebular gas onto
a solid, dense core of mass ~0.04M
J rather than a stellar-like gravitational instability. Thus, detection of a primordial core in Jupiter is a prime objective
for understanding the mode of origin of extrasolar giant planets and other SSOs. A basic method for core detection makes use
of direct modeling of Jupiter’s external gravitational potential terms in response to rotational and tidal perturbations,
and is highly sensitive to the thermodynamics of hydrogen at multi-megabar pressures. The present-day core masses of Jupiter
and Saturn may be larger than their primordial core masses due to sedimentation of elements heavier than hydrogen. We show
that there is a significant contribution of such sedimented mass to Saturn’s core mass. The sedimentation contribution to
Jupiter’s core mass will be smaller and could be zero. |
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| Keywords: | Jupiter Saturn extrasolar planets |
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