A REESTIMATE OF THE PROTOSOLAR (H-2 H-1)(P) RATIO FROM (HE-3/HE-4)(SW) SOLAR-WIND MEASUREMENTS/

We reanalyze the inference of the protosolar abundance of deuterium ma de by Geiss (1993) from measurements of (He-3/He-4)(SW) in the solar w ind. We use an evolutionary solar model with microscopic diffusion, co nstrained to fit the present age, radius and luminosity, as well as th e observed ratio of heavy elements to hydrogen. The protosolar (H-2/H- 1)(p) is obtained from the best fit of (He-3/He-4)(SW). Taking for the protosolar (He-3/He-4)(p) the value measured in Jupiter by the Galile o probe (Niemann et al. 1996), we derive (H-2/H-1)(p) = (3.01 +/- 0.17 ) x 10(-5). Compared to the present interstellar medium value (Linsky et al. 1993), this result is compatible with models of the chemical ev olution of the Galaxy in the solar neighborhood; it is also marginally compatible with the Jovian (H-2/H-1)(F) = (5 +/- 2) x 10(-5) ratio me asured by Galileo.