DPS Pasadena Meeting 2000, 23-27 October 2000
Session 53. Solar System Origin Posters
Displayed, 1:00pm, Monday - 1:00pm, Friday, Highlighted Tuesday and Thursday, 3:30-6:30pm, C101-C105, C211

## [53.04] A new 2-D model of the Solar Nebula constrained by D/H observations in the Solar System : Implications on the the formation of giant planets

F. Hersant (Obs. Paris and CEA Saclay), D. Gautier, J.-M. Huré (Obs. Paris)

From the density temperature profiles of the 2-D solar nebula model of Huré (2000, Astron. Astrophys., in press), we integrate the equation of diffusion which rules the evolution of the D/H ratio in H2O and HCN throughout the nebula. Fitting D/H in LL3 meteorites, comets and Uranus and Neptune constrains the parameters which define 2-D model, namely the initial accretion rate and radius of the nebula, and the \alpha coefficient of turbulent viscosity. The value of turbulent Prandtl number is discussed and chosen equal to 0.7. In this case, the initial accretion rate is between 2.2 \times 10-6 and 1 \times 10-5 solar mass/year, the initial radius of the nebula is between 12.8 and 39 AU, and the \alpha coefficient is betwen 6 \times 10-3 and 5 \times 10-2. The minimum time required to obtain the current mass of hydrogen in Jupiter and Saturn is found equal 0.7 Myr and 5.7 Myr, respectively, after the formation of the Sun. To the contrary, Uranus and Neptune were completed after the dissipation of the nebula, assuming a lifetime of the nebula consistent with values observed in circumstellar disks.