I'm sorry but I don't really understand the question. What is the quest actually asking???
Answer:
Period of brightness variation and luminosity.
Explanation:
The Cepheid variables are used as distance indicators. This requires estimation of periods and (usually) intensity-mean magnitudes in order to establish a period—apparent luminosity relation. It is particularly important for the techniques employed to be as accurate and efficient as possible.
The diffusion coefficient of the gas is proportional to the average rate of thermal motion of the molecules.
the average velocity is inversely proportional to the square root of the molar mass
so
The gas diffusion rate is inversely proportional to the square root of its molecular weight.
Answer: velocity = -0.65 speed =0.65
Explanation:
Velocity =speed+direction speed =distance/time