Hydrogen EOS at megabar pressures and the search for Jupiter's core

William B. Hubbard

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)129-134
Number of pages6
JournalAstrophysics and Space Science
Issue number1-2
StatePublished - Jun 2005


  • Extrasolar planets
  • Jupiter
  • Saturn

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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