energy and momentum. (Remember, the momentum of a photon of energy E is E/c.) When photons from inside the star strike the gas in the outer layers, and are absorbed, their momentum is also absorbed. By conservation of momentum, the shell must move slightly outward.

We do observe shells that are ejected. They are fuzzy in appearance in small telescopes, just like planets; when originally observed, they were called planetary nebulae (Fig. 10.8). (Their name has nothing to do with their properties, but with their appearance as viewed with small telescopes.) From the photograph in Fig. 10.8, we see that

Lines of Sight

0 0

Post a comment