Final answer:
The total energy a star produces per second is known as its luminosity, which is different from its apparent brightness observed from Earth.
Step-by-step explanation:
The total energy that a star produces in one second is known as its luminosity. Luminosity refers to the total energy output of a star across all wavelengths and is an intrinsic property of the star itself. This is different from apparent brightness, which is how bright a star appears to an observer on Earth and depends on both the star's luminosity and its distance from Earth. The apparent magnitude of a star is a measure of its apparent brightness as seen from Earth, whereas absolute magnitude measures the intrinsic brightness or luminosity of the star at a standard distance.