Proper Motions of Water Masers in Circumstellar Shells

K.B. Marvel, P.J. Diamond, A.J. Kemball

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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.
Original languageEnglish (US)
Title of host publicationThe Tenth Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
EditorsR.A. Donahue, J.A. Bookbinder
Pages1621-1628
StatePublished - 1998

Publication series

NameAstronomical Society of the Pacific Conference Series
Volume154

Keywords

  • MASERS, EVOLVED STARS, CIRCUMSTELLAR SHELLS

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    Marvel, K. B., Diamond, P. J., & Kemball, A. J. (1998). Proper Motions of Water Masers in Circumstellar Shells. In R. A. Donahue, & J. A. Bookbinder (Eds.), The Tenth Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (pp. 1621-1628). (Astronomical Society of the Pacific Conference Series; Vol. 154).