SP-345 Evolution of the Solar
System
FIGURE 25.6.3.- Angular velocity of
the Sun as a function of time. It is assumed that the solar system
does not lose any angular momentum to infinity (angular momentum is
conserved within the solar system). As the Sun contracts, its moment
of inertia decreases, so that its angular velocity increases. The
contraction during deuterium burning is small and the angular
velocity remains constant. The B cloud (forming the
Earth, Venus, and Mercury) forms during this period but does not
change the solar angular momentum appreciably. (The A cloud may have formed
earlier). When the C cloud (from which the giant planets accrete) forms,
the Sun loses most of its angular momentum and is brought into
isorotation with Jupiter (period 12 yr). When the deuterium is
totally consumed, the Sun contracts to its present state, with the
moment of inertia decreasing by a factor of 200. The angular velocity
increases by the same factor, accounting for the present angular
velocity of the Sun.
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