A Reestimate of the Protosolar 2H/1H ratio from 3He/4He solar wind measurements

Abstract

We reanalyze the inference of the protosolar abundance of deuterium made by Geiss (1993) from measurements of 3He/4He in the solar wind. We use an evolutionary solar model with microscopic diffusion, constrained to fit the present age, radius and luminosity, as well as the observed ratio of heavy elements to hydrogen. The protosolar 2H/1H is obtained from the best fit of 3He/4He in the solar wind. Taking for the protosolar 3He/4He the value measured in Jupiter by the Galileo probe (Niemann et al. 1996), we derive the protosolar 2H/1H=(3.01 +- 0.17) 10^{-5} ratio. Compared to the present interstellar medium value (Linsky et al. 1993), this result is compatible with models of the chemical evolution of the Galaxy in the solar neighborhood; it is also marginally compatible with the Jovian 2H/1H=(5 +- 2) 10^{-5} ratio measured by Galileo.