ASTR 20 Lecture Notes - Lecture 26: Planetary Nebula, Subgiant, Protostar
Document Summary
An h-r diagram plots the luminosities and temperatures of stars. Most stars fall somewhere on the main sequence of the h-r diagram. Diagram also tells us about stellar radii. Total luminosity depends upon temperature and area. If two stars have the same temperature, the larger of the two will be the most luminous. How to calculate the total luminosity- ***see phone for equation. Stars with lower temperature and higher luminosity than mian-sequence stars must have larger radii: giants and supergiants. Stars with higher t and lower l than main sequence stars must have smaller radii: white dwarfs. H-r diagram depicts: temperature, color, spectral type, luminosity, and radius. A star"s full classification includes spectral type and luminosity class (related to the size of the star): supergiant, bright giant, giant, subgiant, main sequence. Main sequence stars are powered like the sun- by fusing hydrogen into helium in their cores. Luminous main- sequence stars are hot (blue)
