The Zeeman effect or linear birefringence? — VLA polarimetric spectral line observations of H2O masers

  • Jun-Hui Zhao
  • W. M. Goss
  • P. Diamond
7. Water Masers in Star-Forming Regions
Part of the Lecture Notes in Physics book series (LNP, volume 412)


We present line profiles of the four Stokes parameters of H2O masers at 22 GHz observed with the VLA in full polarimetric spectral line mode. With careful calibration, the instrumental effects such as linear leakage and the difference of antenna gain between RCP and LCP, can be minimized. Our measurements show a few percent linear polarization. Weak circular polarization was detected at a level of 0.1 percent of the peak intensity. A large uncertainty in the measurements of weak circular polarization is caused by telescope pointing errors. The observed polarization of H2O masers can be interpreted as either the Zeeman effect or linear birefringence.


Linear Polarization Circular Polarization Zeeman Splitting Zeeman Effect Instrumental Effect 
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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Jun-Hui Zhao
    • 1
  • W. M. Goss
    • 1
  • P. Diamond
    • 1
  1. 1.National Radio Astronomy ObservatorySocorro

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