Monitoring of water masers from IRAS sources

Twenty-three water vapor masers in the direction of IRAS sources in the Southern Hemisphere had their intensities monitored systematically at Itapetinga Radio Observatory. These masers were detected in four surveys in which each run had different selection criteria. The IRAS fluxes analysis and the shape of the spectra of these masers suggest that the objects are associated with premain sequence stars, still surrounded by the dust cocoon. Almost all sources presented drastic changes in the overall spectral line distribution in their spectra.