What is parallax?
A displacement/difference of an object viewed along two different lines of sight
What is luminosity?
Luminosity measures the total amount of energy emitted by a star
How do we measure stellar luminosities?
By measuring the star's apparent brightness and distance
How do we measure stellar temperatures?
By measuring the spectrum of light that stars emit
What is a Hertzsprung-Russell diagram?
A diagram that plots the stellar luminosity of stars versus surface temperature
What is the significance of the main sequence?
A star's mass determines its position along the main sequence
(high mass= luminous and blue, low mass=faint and red)
Who was Ejnar Hertzsprung?
He determined the differences of stars by statistical parallax and helped to create the Hertzsprung-Russell diagram
Who was Henry Norris Russell?
Helped to develop the Hertzsprung-Russell diagram
What is the mass of Betelgeuse?
20 times the mass of the sun
What is the parallax of Sirius?
approximately .377 arc seconds
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