Astro Notes November 3rd

Astro Notes November 3rd - Astro Notes November 3rd...

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Astro Notes November 3 rd Observations properties of stars So far b, d, L, T, Composition and spectral classification Spectral classification O B A F G K M L T Hot-- Coool 35,0000K-------------1500 K Why should combined strength of absorption lines be related to the temperature of the photosphere Meghnad saha Cecela Payne 1925 E.g H lines are strong in A and F stars A- 10,000K F- 7000 K Answer Goldilocks effect O stars T= 30,000K (huge number of every energetic photons) Energy comes into an H atom ionized to knock completely off atom M Star T= 3000K atom with electrons sitting on outside photons come in but they tend to be weak and not enough of high enough energy to make the electron moves around or jump between orbitals H lines are weak Eg H lines are stron in A and F stars A= 10,000 K F= 7,000 K These aare just right Photo in large numbers with right energy for absorbtion Done 1880 1929
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Radius and Mass (Later Radius: R Direct ovservation for near by large stars juse possible Either way: black body radiators Luminosity L proportional to Temperatur ^ 4 x (surface area) L proportional to Temp ^ 4 Radius^2 Radius proportional to Squared root (Luminosity / temperature History 1880-1920 Edward Pickering Director of havard college observatory Henry draper Catalog 400,000 stars Science Collect Data then look for patterns Herspring—Russell diagram (Hr Diagram)
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This note was uploaded on 12/01/2009 for the course ASTR 50800 at USC.

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Astro Notes November 3rd - Astro Notes November 3rd...

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