Question

What process heated the early solar nebula as it slowly condensed toward a central protosun?

A) radioactive decay of heavy elements originally formed in the Big Bang
B) release of heat as molecules formed and gases condensed into ices
C) thermonuclear fusion in the protosun, followed by radiative heating of the nebula
D) release of heat by collisions of particles as they gained kinetic energy in falling toward the center of the nebula

Answer 1

The early solar nebula was heated by collisions of particles that gained kinetic energy as the cloud contracted, converting gravitational potential energy into thermal energy, which is distinct from nuclear fusion processes that occur later in a star's life. The correct option is D.

Step-by-step explanation:

The process that heated the early solar nebula as it slowly condensed toward a central protosun was the release of heat by collisions of particles as they gained kinetic energy in falling toward the center of the nebula. As the nebula contracted under gravity, particles moved faster and collided more frequently, converting potential gravitational energy into thermal energy. This process of heating is separate from nuclear fusion, which occurred later in the dense core of the protosun leading to the formation of a star.

Nucleosynthesis and nuclear fusion are critical for star formation and involve combining smaller nuclei into larger ones, releasing energy and synthesizing new elements. The early universe also experienced nucleosynthesis when it was a few minutes old, allowing protons and neutrons to combine and form deuterium and helium.

Hence, Option D is correct.