A two-fluid, MHD coronal model

We describe first results from a numerical two-fluid MHD model of the globa l structure of the solar corona. The model is two-fluid in the sense that i t accounts for the collisional energy exchange between protons and electron s. As in our single-fluid model, volumetric heat and momentum sources are r equired to produce high speed wind from coronal holes, low speed wind above streamers, and mass fluxes similar to the empirical solar wind. By specify ing different proton and electron heating functions we obtain a high proton temperature in the coronal hole and a relatively low proton temperature ab ove the streamer tin comparison with the electron temperature). This is con sistent with inferences from SOHO/UltraViolet Coronagraph Spectrometer inst rument (UVCS) [Kohl ct al., 1997], and with the Ulysses/Solar Wind Observat ions Over the Poles of the Sun instrument (SWOOPS) proton and electron temp erature measurements which we show from the fast latitude scan. The density in the coronal hole between 2 and 5 solar radii (2 and 5 Rs) is similar to the density reported from SPARTAN 201-01 measurements by Fisher and Guhath akurta [1994]. The proton mass flux scaled to 1 AU is 2.4 x 10(8) cm(-2) s( -1), which is consistent with Ulysses observations [Phillips ct al., 1995]. Inside the closed field region, the density is sufficiently high so that t he simulation gives equal proton and electron temperatures due to the high collision rate. In open field regions tin the coronal hole and above the st reamer) the proton and electron temperatures differ by varying amounts. In the streamer the temperature and density are similar to those reported empi rically by Li et al. [1998], and the plasma beta is larger than unity every where above similar to 1.5 Rs, as it is in all other MHD coronal streamer m odels [e.g., Steinolfson ct al., 1982; also G. A. Gary and D. Alexander, Co nstructing the coronal magnetic field, submitted to Solar Physics, 1998].