The variability curves presented here deal with the integrated fluxes of the
red, blue and intermediate peaks, when they exist, in each emitting OH maser line
as well as the maximum intensity variations of the spectral components. These
latter components were determined through a spectral decomposition by
Gaussian fitting (Etoka 1996).
Observations of Miras at high velocity resolution, show that
the spectral profile of these sources is not smooth, but is in fact
composed of numerous rather narrow components blended together. Up to now,
only the global integrated flux has been considered. According to a
spectral decomposition method based on Gaussian fitting (Etoka
1996), we are able to study the OH variations in a more precise way. The
accepted tolerance on the velocity divergence under which a component was
considered to be the same from one fit to another was taken to be 1.5 times
the poorest velocity resolution of the whole data set (i.e., 0.14 km s-1).
This leads to a tolerated divergence of 0.2 km s-1.
Let us define the degree of circular polarization as follows:
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