We present a preliminary model for time variations of type I H2O masers. We discuss the possibility that the variation in radial velocity of some H2O maser features reflects an actual variation in the kinematic state of the maser cloudlet. This mechanism, however, results in an insufficient range of variations and produces only monotonic variations. It is therefore not favored. On the other hand, a computation of feature blending shows that blending of intensity-varying features adjacent in the spectrum can account for the radial velocity variation. With constant maser pumping rate, we attribute the flux density variation to the rotation of the whole maser and/or the possible spin of the maser cloudlets, and to Kelvin-Helmholtz instability occurring on the surface of the cloudlet. A model that combines these two elements is able to simulate flux density variations with sufficient amplitudes and a wide range of time scales (102 - 108 s). Since any variation of maser pumping rate was excluded, the results cannot describe the actual flux density variation over a long time period (> 1 yr). However, the model is thought to adequately describe the flux density variation of type I H2O masers in an ordinary, physically quiet environment.
Peng RS. Time Variation of Type-I H2O Masers. II - a Preliminary Model for the Time Variation of H2O Masers in Ordinary Physically Quiet Environments[J]. ASTRONOMY & ASTROPHYSICS,1989,216(1-2):173-184.
APA
Peng RS.(1989).Time Variation of Type-I H2O Masers. II - a Preliminary Model for the Time Variation of H2O Masers in Ordinary Physically Quiet Environments.ASTRONOMY & ASTROPHYSICS,216(1-2),173-184.
MLA
Peng RS."Time Variation of Type-I H2O Masers. II - a Preliminary Model for the Time Variation of H2O Masers in Ordinary Physically Quiet Environments".ASTRONOMY & ASTROPHYSICS 216.1-2(1989):173-184.
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