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1969 - Formation of Planetary Systems by Aggregation.md

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Formation of Planetary Systems by Aggregation: A Computer Simulation

This is the main paper that the accretion part of the simulation is based upon. It was written in 1969 by Stephen Dole.

Basic Assumptions:

  • 1 star of 1 solar mass and 1 solar luminosity (basically equivalent to our own star)

  • Planets can form between the radii 0.3 astronomical units (AU) and 50.0 AU.

  • Planets form from a spherically symmetrical cloud of dust and gas with a constant ratio of gas to dust with the density decreasing with the distance from the center.

  • All particles in the cloud are moving on elliptical orbits with the center of mass (star) at one focus.

  • All particles in the cloud have the same orbital eccentricity

Features

  • Generates a Believable (for the 60s/70/s/80s) Sol-like Solar System.
  • Accretion algorithm for sequentially adding/growing/merging protoplanets as long as there is gas and dust remaining.
  • Distinguishes between rocky and gas planets.

Limitations:

In Recreation:

  • No way to recreate exact tests results; even with a seed listed in the sample run, the age of the computer hardware he used means that accurately recreating the pseudo-random number sequence is a tall order without the original software to hand. (internal random number generator of an IBM 7044 PC).

With the Model:

  • Collision calculations are less than accurate due to not taking into account any axial inclinations on the orbital plane.

  • No consideration given to the accretion of satellites.

  • Dust Density Calculation are in 2D

  • Dust / Gas removal is a discrete event, rather than a gradual one

  • No consideration given to the kind of atmosphere that rocky planets will have.

  • Arbitrarily set the outer and inner limits at with planets can form.

Compilation

N/a - no source