physikYou can weigh a star by watching its planets spin around it. The planets make the star wobble. The size of the wobble allows us to know a RATIO of star weight to planet weight. If we can figure a planet's weight based on rock density (4 grams per cubic centimeter) and its iron core (10 grams per cubic centimeter) we can know the stars weight to a few percent.
We don't even have to see the planets or the wobble of the star. By using a spectragraph, we can detect the wobble as red shift (star moving away from us) and blue shift (star moving toward us). This gives us the period of the wobble for stars too far away to directly detect the wobble in a telescope.
You can estimate the size of a star by its luminosity (brightness) and how far away it is. This gives the "absolute magnitude" (how bright the star would be at the distance of our sun). Hertzsprung and Russell came up with a weight to brightness ratio for stars that is always true to a few percent.
awesome tho
we are fucking small :D
appropriate joke.
We don't even have to see the planets or the wobble of the star. By using a spectragraph, we can detect the wobble as red shift (star moving away from us) and blue shift (star moving toward us). This gives us the period of the wobble for stars too far away to directly detect the wobble in a telescope.
You can estimate the size of a star by its luminosity (brightness) and how far away it is. This gives the "absolute magnitude" (how bright the star would be at the distance of our sun). Hertzsprung and Russell came up with a weight to brightness ratio for stars that is always true to a few percent.