{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Planet Formation\n", "\n", "*Paul O. Hayne*\n", "\n", "Planets form through a process of *accretion* of gas and dust within circumstellar disks, which are made of raw materials condensed from the *protostellar nebula*. The nebula itself begins as a relatively dense fragment (\"core\") collapsing under self-gravity from within a larger *molecular cloud*, composed primarily of hydrogen gas (H$_2$). After H, the next most abundant element is He, followed by O, C, N, Ne, Mg, Si, Fe, S, Ar. These are the raw materials from which stars and planets form (Fig. 1).\n", "\n", "---" ] }, { "cell_type": "code", "execution_count": 7, "metadata": {}, "outputs": [ { "data": { "text/html": [ "\n", "
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