Maser Line Profiles and Mass Outflow of Long-Period Variable Stars

Extract

The long-period variable giants with maser emission (maser/LPV stars) can be divided into two groups. The stars in group 1 have color indices I (0.84μ) - K (2.2µ) < 6, those in group 2 have I - K≥6. Fig. 1 gives the velocity structure of the maser lines for both groups. I have included only those maser /LPV stars for which the radial velocity of the star is known. In most cases this is the mean velocity of the outer OH peaks (Winnberg, this Colloquium), but for R Leo and R Cas the stellar velocity is found from the ground-vibrational state SiO emission (Reid and Dickinson, 1976). The abscissa of fig. 1 gives the velocity relative to the stellar velocity and the verticale scale gives the number of stars that show emission in a specific line at the relative velocity indicated. Note that the “line profiles” obtained in this way are not real mean profiles, because I only counted the presence of emission, weak or strong.