Table 1 shows the column densities,N H, calculated from equation (3) for typical stellar parameters and mass loss rates as compiled in ref.13.

This column density could cause factor of 100 attenuation in an active-region-like spectrum.

The density varies with season; the average column density is roughly 4 billion sodium atoms/cm.

The absolute air mass at zenith is also known as the column density.

Some algebra shows the vertical column density to be given by:

In atmospheric sciences, this is referred to as a column density.

To get a column density, we must integrate the total column over a height.

Methods applied so far have relied on column density derived from near infrared extinction and even star counting in a bid to probe these objects further.

They determine an upper limit for the column density of the ν state 3x10cm.

This equation assumes that the extinction coefficient is known, or that N, the column density, is known.