Published online by Cambridge University Press: 03 August 2017
A sample of 14 water maser sources associated with young stellar objects (YSOs) has been monitored over 13 years with the Medicina 32-m antenna. The YSOs have been selected with bolometric luminosities from 20 L⊙ to 2 × 106 L⊙ with the aim of investigating the relationship between H2O maser variability and stellar mass. The results are presented in various graphical forms which allow to follow the variation of the different spectral components. In particular, four quantities have been considered in our analysis: the intensity of the maser lines as a function of time and velocity; the flux integrated over the observed velocity range as a function of time; the maximum flux ever observed at each velocity; and the frequency of occurrence of the maser emission at any given velocity.