ANALYSIS
Calculation of Abundances
In order to calculate the abundances of an element in a spectrum, the area of its absorption lines must be determined. To do this, a curve must be fit to the spectrum to represent the continuum. For each absorption line, a triangle is supposed. The area of this triangle is equivalent to (1/2)(base)(height), with the height as the central depth. This area is also known as the equivalent width. In weak lines, the equivalent width tends to be proportional to the abundances. However, there is an alternate method which uses the central depths of the stars. This is discussed in the examples seen on the following page.