Our Old Friend the Doppler Effect
You’dbe hardput these days topickupany bookonastronomy and notfindsomewhere in its pages mention of the Doppler effect; this might be to dowith the proper motions of stars, the radial velocities of a binary star components or perhaps most famous of all the expansion of theUniverse (of coursewe knownowthat this actually isn’t aDoppler effect at all but the expansion of spacetime itself, even though mathematically the two effects are identical). As we shall see in the next chapter this most valuable of effects plays a big role in spectra too; first though for completeness I shall explain it here and we’ll also have a look at how important the ‘clever astronomer’s’ relativistic version of the Doppler effect really is.
KeywordsOrbital Period Radial Velocity Doppler Effect Wavelength Shift Radial Motion
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