Calculations of the evolution of the giant planets

Abstract Evolutionary calculations are presented for spherically symmetric protoplanetary configurations with a homogeneous solar composition and with masses of 10 −3 , 1.5 × 10 −3 , 2.85 × 10 −4 , and 4.2 × 10 −4 M ⊙ . Recent improvements in equation-of-state and opacity calculations are incorporated. Sequences start as subcondensations in the solar nebula with densities of ∼10 −10 to 10 −11 g cm −3 , evolve through a hydrostatic phase lasting 10 5 to 10 7 years, undergo dynamic collapse due to dissociation of molecular hydrogen, and regain hydrostatic equilibrium with densities ∼1 g cm −3 . The nature of the objects at the onset of the final phase of cooling and contraction is discussed and compared with previous calculations.