A35 Lectures 12-13 - Lecture 12 Lives of the Stars[Telescope review and adaptive optics covered on the midterm Spectra of stars depend(mostly on their

A35 Lectures 12-13 - Lecture 12 Lives of the...

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Lecture 12: Lives of the Stars [Telescope review and adaptive optics covered on the midterm] Spectra of stars depend (mostly) on their temperatures, not on the distance! (Also depends on wavelength) H-R Diagram: Plots Luminosity vs. Temperature (increasing to the left!) You also need the flux and the parallax to measure the luminosity Amazing fact: stars are not found everywhere in this plot Most stars lie on the “main sequence” Lecture 13: The Secret Lives of Stars VLA – Very Large Array; radio telescope Inverse Square Law : flux (i.e. brightness) decreases proportionally to the square o the distance (remember he had those big square things in lecture – as the light travels it has more and more area to go through, thus more spread out and brightness decreases); need distance to compute luminosity (and flux) o L = 4πD 2 x flux [watts] Stars classified into spectral types based mostly on temperature
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  • Spring '09
  • RobertKirshner
  • main sequence

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