Kashima 34-m water maser survey of late-type stars

This paper presents new results of a water maser survey of late-type stella r objects at 22.235 GHz with the Kashima 34-m radio telescope. We have dete cted 179 out of 643 observed sources, including 32 new detections. The sour ces were selected in terms of the IRAS flux density and colors of late-type stars, involving optically observable Mira/semiregular variables, IRC obje cts, OH/IR sources and protoplanetary nebulae. We found the highest H2O det ection rate for the type of stars with a thin dust envelope (Mira/semiregul ar variables) among other types of sources. This is attributed to the small er distances to such stars in the sample. The velocity spread of the H2O ma ser profile has an increasing tendency with the IRAS color, though it becom es more difficult to access this color dependence beyond an edge of the tra nsition of the (oxygen-rich) Asymptotic Giant Branch stars to protoplanetar y nebulae in the two-color diagram.