SHORT-TERM RADIAL-VELOCITY VARIATIONS OF WATER-VAPOR MASER SPECTRAL COMPONENTS IN STAR-FORMING REGIONS

The radial-velocity variability of individual spectral features of H2O maser sources associated with star-forming regions is analyzed. Seven sources (S252A, ON1, ON2, W75N, W75S, S128, and S140) are considered. In addition to the regular drift that is present for virtually all th e spectral features, short-term radial-velocity variability was detect ed. For some features, this variability is more or less periodic, with periods from 1 to 2.5 years and amplitudes from 0.03 to 0.24 km/s. Th e lifetime of such features in their active phase was from two to nine years, Possible mechanisms for the observed radial-velocity variation s are discussed. The most probable origins may be clumpiness and turbu lence in the medium hosting the water-vapor masers.