UVCS observations and modeling of streamers

We present results derived from the analysis of an equatorial streamer stru cture as observed by the UVCS instrument aboard SOHO. From observations of the H I Ly alpha and Ly beta lines we infer the density and temperature of the plasma. We develop a preliminary axisymmetric, magnetostatic model of t he corona which includes the effects of gas pressure gradients on the magne tic structure. We infer a coronal plasma beta > 1 in the closed field regio ns and near the cusp of the streamer. We add to the model a parallel veloci ty field assuming mass flux conservation along magnetic flux tubes. We then compute the Ly alpha emissivity and the line-of-sight integrals to obtain images of Ly alpha intensity, taking into account projection effects and Do ppler dimming. The images we obtain from this preliminary model are in good general agreement with the UVCS observations, both qualitatively and quant itatively.