ASTR 1102 Lecture : Lecture14
Document Summary
Is the sun a typical star? (part 1) Luminous stars are less common than faint ones: The sun is among the more luminous stars in our neighborhood. Most luminous supergiant stars in the galaxy over 1,000,000 l ! E. g. for every 10,000 l star there are about 10,000 stars as luminous as the sun. Luminous stars burn nuclear fuel faster, so do not live so long. Luminosity is energy output, not apparent brightness. Stefan-boltzmann law - hotter stars are more luminous. Sirius is hotter than the sun (~10,000k) and more luminous. Betelgeuse has luminosity 41,000 l , but is cooler than the. Betelgeuse is much larger - it is a supergiant . The luminosity of a star is set by. Not doppler effect - color changes would be too small to see. Can estimate temperature even for faintest stars. Ratio of visual to blue is lower. There is another way to make a star red.
