SCI 102 Lecture Notes - Lecture 4: Cosmic Microwave Background, Radial Velocity, Radio Astronomy
13 Apr 2016
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Radial velocity problem: h spectral line is = 656. 2850 nm in the lab. = 656. 2927 nm in the spectrum of regulus. Radial velocity? vr = (3 x 108m/s)(656. 2927 -656. 2850) nm. 656. 2850 nm vr = 3519. 8123 m/s vr = 3. 52 km/s. When star > lab -> red shifted, moving away from you. When star < lab -> blue shifted, moving towards you. Use doppler to tell if a star is rotating by measuring each edge. Light-year = ly: distance that light travels in one year. Parsec = pc: 1 pc = 3. 26 ly. Astronomical unit = au: average distance between the earth and sun: 1 au = 1. 5 x 1011m. A galaxy is a large assemblage of stars which orbit a common center all held together by gravity contains from a few thousand to trillions of stars. Hubble and humason determined the distances and radial velocities of faraway galaxies. All faraway galaxies are redshifted and receding from us.
