Using equation (6.22) gives

1.7 X 10"24 | = 1.2 X 106 cm/s From equation (5.4), we estimate the linewidth as

In any spectral line, smaller Doppler shifts relative to the line center are more likely than larger ones. Therefore, the optical depth is greatest in the line center, and falls off to either side. At different Doppler shifts away from the line center, we will see different distances into the Sun. The farther we are from the line center, the deeper we see. By studying line profiles in detail we learn about physical conditions at different depths. Also, each spectral line has a different optical depth in the line center, so different lines allow us to see down to different depths in the photosphere. When we perform model stellar atmosphere calculations, we try to predict as many of the features of the spectrum as possible,

0 0

Post a comment