Question

Which best describes stellar equilibrium?
O
A. The star produces fuel at the same rate it burns fuel.
O
B. The core contains equal amounts of hydrogen and helium.
O
c. Pressure caused by fusion reactions in the core is balanced by the
gravity exerted by the sun's mass.
O
D. Heat produced during fusion reactions in the core is transferred to
the surface.

Answer 1

The correct answer is letter B.

Explanation: Even for the best studied star we can only measure 4 parameters: mass, luminosity, radius and chemical composition of the outer layers. We can determine the structure of the star with these parameters, because we have one more condition: the constancy of the stars over long periods of time. Even variable stars have long-term stability of the average structure. The existence of fossil algae on the earth over 1 billion years old and fossils up to 3.5 billion years old is evidence that the temperature of the earth cannot have changed by more than about 20 ° C. Therefore, the interior of the stars must be in perfect balance.