AST201H1 Chapter Notes -Main Sequence, White Dwarf, Instability Strip
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AST201H1 Full Course Notes
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15. 2 patterns among stars: color = surface temperature (red: cooler/blue: hotter, luminosity is dependent on surface temperature, and surface area. If two stars have the same surface temperature, the larger will be more luminous: h-r diagrams: Luminosity & spectral type are all that"s required to plot a star on h-r. Surface temperature: x-axis (relates to spectral type) Luminosity: y-axis (in units of the sun"s luminosity (lsun)) Each tick on the y-axis is 10 times that of the one before it. Stellar masses decrease downward along the main sequence. Stars cluster in 4 major groups: main sequence: Most stars fall along here (including the sun) Runs from the upper left corner to the lower right on the h-r supergiants: Upper right (very large, and bright) giants: Still much larger and brighter than main sequence stars of same spectral type white dwarfs: White (due to their high temperature: luminosity classes: The region on the h-r in which a star falls.