The apparent movement of a star in comparison to its background.
What is luminosity?
The amount of power a star radiates. (energy per second = watts)
How do we measure stellar luminosities?
Luminosity is equal to 4 times pi times the distance squared times the apparent brightness.
How do we measure stellar temperatures?
by measuring the type of light that is emitted by the star.
What is a Hertzsprung-Russell diagram?
A diagram used to cross measure temperature and luminosity.
What is the significance of the main sequence?
Most stars we know, including our sun are in the main sequence
Who was Ejnar Hertzsprung?
An astronomer and chemist who helped develop the Hertzsprung–Russell diagram.
Who was Henry Norris Russell?
An astronomer who helped develop the Hertzsprung–Russell diagram.
What is the mass of Betelgeuse?
About 20x the mass of the Sun.
What is the parallax of Sirius?
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