Jupiter models with improved ab initio hydrogen EOS (H-REOS.2)

TL;DR

This paper introduces an improved ab initio hydrogen equation of state, H-REOS.2, enabling more accurate Jupiter models that align with observed atmospheric compositions and provide insights into its internal structure and evolution.

Contribution

The paper presents the H-REOS.2 hydrogen EOS and applies it to Jupiter modeling, resulting in models consistent with observed heavy element abundances and internal structure constraints.

Findings

Jupiter models with H-REOS.2 suggest a core mass of 0-8 Earth masses.

Total heavy element mass in Jupiter is estimated at 28-32 Earth masses.

Predicted internal oscillation frequencies and moment of inertia are insensitive to core mass.

Abstract

The amount and distribution of heavy elements in Jupiter gives indications on the process of its formation and evolution. Core mass and metallicity predictions however depend on the equations of state used, and on model assumptions. We present an improved ab initio hydrogen equation of state, H-REOS.2 and compute the internal structure and thermal evolution of Jupiter within the standard three-layer approach. The advance over our previous Jupiter models with H-REOS.1 by Nettelmann et al.(2008) is that the new models are also consistent with the observed 2 or more times solar heavy element abundances in Jupiter's atmosphere. Such models have a rock core mass Mcore=0-8 ME, total mass of heavy elements MZ=28-32 ME, a deep internal layer boundary at 4 or more Mbar, and a cooling time of 4.4-5.0 Gyrs when assuming homogeneous evolution. We also calculate two-layer models in the manner of Militzer et al.(2008) and find a comparable large core of 16-21 ME, out of which ~11 ME is helium, but a significantly higher envelope metallicity of 4.5 times solar. According to our preferred three-layer models, neither the characteristic frequency (nu0 ~156 microHz) nor the normalized moment of inertia (~0.276) are sensitive to the core mass but accurate measurements could well help to rule out some classes of models.