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Published online by Cambridge University Press: 14 August 2015
Time-resolved spectroscopy of the gaseous ring of RW Tau has revealed characteristics of its structure. Observations of H-alpha emission during one eclipse show a partial eclipse of the ring which is brighter at second contact than at third contact. The radial velocities became nearly constant after mideclipse. During two other eclipses the emission continued to strengthen after second contact. X Per has shown variability on a time scale of minutes. On one occasion H-alpha emission decreased in strength by a factor of two in 90 seconds.