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| Paper: |
Proper Motions of Water Masers in Circumstellar Shells |
| Volume: |
154, Cool Stars, Stellar Systems and the Sun: Tenth Cambridge Workshop |
| Page: |
1621 |
| Authors: |
Marvel, K. B.; Diamond, P. J.; Kemball, A. J. |
| Abstract: |
We present proper motion measurements of circumstellar water masers obtained with the VLBA. The objects observed include S Persei, VX Sagittarii, U Herculis, VY Canis Majoris, NML Cygni, IK Tauri and RX Bootis. Results of the observations and modeling indicate that the water masers exist in a kinematically complex region of the circumstellar envelope, which is not well fit by the standard model of a uniformly expanding spherical wind. Attempts at fitting an ellipsoidal geometric distribution with a variety of kinematic models are presented. Estimates for the distances of the stars are also discussed. A change in position of the maser spots as a function of velocity has been measured. This effect may be used to place limits on accelerations in the masing gas. |
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