Minimum mass solar nebula model

SEDs) demonstrate that massive disks often extend to hundreds of astronomical units. A lower estimate for the initial mass distribution of our Solar System is provided by the minimum mass solar nebula (MMSN) model, which is the minimum mass required to produce the observed distribution of solids from a disk with solar composition. This analysis predicts a disk mass between 0.01 and 0.07 M extending out to 40 AU. Mass estimates for circumstellar disks derived from submillimeter and longer-wavelength observations are consistent with the range estimated for the MMSN (e.g. Beckwith et al. 1990 Williams etal. 2005). 

Turbulent mixing and dust disk evolution models for a range of stellar and disk masses correlations are much easier to observe and more difficult to fit than simulations restricted to the minimum-mass solar nebula... 

Attempts to model the accretion of Uranus and Neptune from planetesimals orbiting 20-30 AU from the Sun (the current locations of these planets) have met with severe difficulties. Long orbital periods in the outer solar system mean that accretion occurs very slowly. In addition, solar gravity is sufficiently weak here that gravitational interactions between planetary embryos would have ejected a substantial amount of mass from this region of the disk (Levison and Stewart, 2001). Numerical simulations show that it is unlikely that bodies larger than Earth could have accreted in situ at the locations of Uranus and Neptune, even if the nebula was substantially more massive than the minimum-mass nebula (Thommes et al., 2003). 

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