Modeling Planetary Accretion
Isaacman and Sagan (1977) say that any model of solar system formation should be able to account for three main solar system characteristics. What are these characteristics? (3 points)
Explain how the ACRETE model determines whether a particular dust grain sticks to an accretion nucleus. Include any relevant mathematical expressions in your answer, and define the variables used. (3 points)
What additional requirement is necessary for the accretion nucleus to collect gas? (2 points)
Compare the two values of 0, and use this information to explain why the model generates terrestrial and Jovian planets. (4 points)
Describe and explain the results of varying the ratio of gas to dust K. (3 points)
What happens at nebular masses below 0.02 Me? Why is 0.2 M. the upper limit? (4 points)
The range of nebular mass from 0.02 M. to 0.2 M. is much smaller than the nebular mass of 1 M., which is used by astronomers studying the earlier history of the solar system. Why do Isaacman and Sagan not find this discrepancy problematic? (3 points)
Describe and explain the outcome of changing the eccentricity (r) of the dust particles in the nebula. (5 points)
Would you say that the model is sensitive or insensitive to changes in the distribution of density in the nebula? Support your conclusion with examples from the paper. (5 points)
Isaacman and Sagan (1977) find that the model produces planetary spacings that appear to be consistent with Trout-Bode-type laws, even for very unusual planetary systems. How do the authors interpret this outcome? (2 points)
