Building Planets at PSI: Current Research in Progress

Current Research in Progress

Table of Contents

Introduction

Published Results and Abstracts

Current Research in Progress

Building Planets: An Example
The attached figure shows an example of the planet-building model in action. In the first step, the early solar system has particles in a size range up to 10²⁶ grams near 0.5 AU, and considerabley less beyond 1 AU.

Building planets with the PSI computer program. These three graphs show a typical output of the current PSI planet-building program. Each diagram shows a size distribution of planetesimals, (log number vs. log mass) at different distances from the sun (distance "a," measured in astronomical units, or AUs).

The first graph is 10,000 years after the start of the process. Size distributions show many small particles and few large particles. No particles are bigger than 10²⁶ grams. Earth's current mass is 6 x 10²⁷ grams.

The second graph is 100,000 years after the start of the process. on the end closer to the sun, we can see that the small particles are being depleted as they aggregate into a few larger bodies. Some of the largest bodies are larger than 10²⁶ grams.

The third graph shows the condition after 1 million years. Now, the largest bodies are beginning to become independent "planets" with more than a dozen bodies larger than 10²⁶ grams. At the same time, the system of small planetesimals is gradually being consumed to make the larger bodies.

These diagrams are taken from a paper by Weidenschilling, Spaute, Davis, Marzari, and Ohtsuki (1997, "Accretional Evolution of a Planetesimal Swarm 2. The Terrestrial Zone." Icarus, 123: 429- 455.

Building planets with the PSI computer program. These three graphs show a typical output of the current PSI planet-building program. Each diagram shows a size distribution of planetesimals, (log number vs. log mass) at different distances from the sun (distance "a," measured in astronomical units, or AUs).
	The first graph is 10,000 years after the start of the process. Size distributions show many small particles and few large particles. No particles are bigger than 10²⁶ grams. Earth's current mass is 6 x 10²⁷ grams.
	The second graph is 100,000 years after the start of the process. on the end closer to the sun, we can see that the small particles are being depleted as they aggregate into a few larger bodies. Some of the largest bodies are larger than 10²⁶ grams.
	The third graph shows the condition after 1 million years. Now, the largest bodies are beginning to become independent "planets" with more than a dozen bodies larger than 10²⁶ grams. At the same time, the system of small planetesimals is gradually being consumed to make the larger bodies.
These diagrams are taken from a paper by Weidenschilling, Spaute, Davis, Marzari, and Ohtsuki (1997, "Accretional Evolution of a Planetesimal Swarm 2. The Terrestrial Zone." Icarus, 123: 429- 455.