Luminosity (absolute brightness) is the amount of energy emitted by a star each second. Stars radiate light over a broad range of frequencies in the electromagnetic spectrum, from the low energy radio waves to high energy gamma rays. The luminosity of a star depends on two factors:
A age and surface area.
B surface area and temperature.
C gravity and distance from Earth.
D distance from Earth and temperature.
The correct answer is B: surface area and temperature.
Explanation: A star’s luminosity is primarily determined by its surface area (or radius) and its temperature. The Stefan-Boltzmann Law states that the luminosity of a star is proportional to the fourth power of its temperature (in Kelvin) and its surface area. This means that a larger and hotter star will emit more energy than a smaller or cooler star.