Asked Nov 22, 2019
describe how the 21-cm line of hydrogen is formed. Why is this line such an
important tool for understanding the interstellar medium

Expert Answer

Step 1

In space almost all of the hydrogen atoms are in ground state. The electron moves around the proton has a spin in the same direction as the proton’s spin (parallel spin) or the electron may have spin in opposite direction of the proton (antiparallel spin).

The energy state of an electron which is spinning in the anti-parallel direc...

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