Stellar H2O masers

Abstract

Preliminary results of an observational program to determine the incidence of H2O maser emission among cool stars are discussed. To date, 17 new H2O masers have been found which are associated with stars in the Two-Micron Sky Survey or General Catalog of Variable Stars. An updated catalog of all known H2O/IR stars, including the most accurate available positions, is presented, and an analysis is given of the 0.9-20-micron photometry of these sources from the Two-Micron Sky Survey and the AFGL Infrared Sky Survey. These photometric data suggest that there is a strong dependence of the detectability of H2O maser emission on 2.2-micron brightness and that pumping by radiation near 2 microns is unlikely for some stars, but the flux near the 6.3-micron vibrational transition may be sufficient for all of them.