NATS 1745 Lecture Notes - Lecture 16: Blueshift, Binary Star, Christian Doppler
13 Mar 2016
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Lecture 16: the doppler shift understanding the doppler shift method first astronomical observation of redshift using the doppler shift to study binary star orbits using doppler shift to find exoplanets: radial velocity method. Kepler spacecraft & hunt for alien earths using doppler shift to find black holes: stellar and supermassive. Christian doppler: propose that the frequency of light + sound get affected by the relative motion of a source + an observer. Perceived frequency shifts to higher frequency if source is moving towards us + lower frequency if source is moving away from you. Thought he could explain: red stars --- moving away from earth, blue stars --- moving towards earth, wrong: colour is due to temperature, not well received ---- in 1845 demonstrated idea with trumpet players (see pdf for details) 1868: 1st example of a stellar spectra affected by the doppler shift. William huggins observed sirius saw a red-shifted spectra --- concluded sirius is moving away from us.
