PHYS 183 Lecture Notes - Lecture 28: Doppler Broadening, Doppler Effect, Molecular Cloud
21 Apr 2018
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Document Summary
Lots oh helium and hydrogen in the universe in general. For every type of molecule there are certain vibrational, rotational modes that are excited by certain wavelengths of light. In stars (esp. hot stars) there are no molecules as temperatures are to high. Molecules absorb specific wavelengths of light too: due to motion of molecules. Moving gas particles, at high temp, absorb wider range of wavelengths, due to doppler shifting of particles some moving away from observer, some moving towards. Atomic hydrogen can absorb and emit light at wavelength = 21 c, frequency =1420 mhz. Hydrogen can flip, and emit light when it does does not happen often. Observed in 1951 by ewen and purcell. Predicted to be observable in 1944 by van der hulst. Stars are formed from h, he from the big bang along with from material in molecular clouds. Those stars spend their lives producing the elements heavier than h, he (up to fe)
