The H-R diagram main-sequence of stars has a limit at the lower-mass or energy-output end because
A)low-mass stars form from the interstellar medium very rarely.
B)low-mass objects are composed primarily of solids, not gases.
C)pressure does not depend on temperature in degenerate matter.
D)the lower limit represents when the radius of the star would be zero.
E)there is a minimum temperature for hydrogen nuclear fusion (the definition of a star).

Question

Quizplus · Accepted Answer

The minimum temperature required for hydrogen nuclear fusion (about 10 million K) is the defining characteristic of a star. Below this temperature, the object cannot sustain nuclear fusion and is not considered a true star. This sets a lower limit on the mass and energy output of stars, which is reflected in the lower end of the main-sequence on the H-R diagram.

The H-R Diagram Main-Sequence of Stars Has a Limit at the Lower-Mass