Three-fluid 2.5-dimensional magnetohydrodynamic model of the effective temperature in coronal holes

Recent SOHO Ultraviolet Coronagraph Spectrometer (UVCS) observations show that protons and minor ions are hot (T-p > 10(6) K, T-i > 10(7) K) and anisotropic in coronal holes. A possible cause of the large perpendicular motions is unresolved fluctuations in the solar wind. Using the three-fluid Alfvenic 2.5-dimensional MHD model, we have shown that the unresolved fluctuations lead to apparent Alfvenic proton temperature and anisotropy consistent with UVCS observations. However, waves with Alfven realistic amplitudes cannot reproduce the O5+ perpendicular temperature and anisotropy deduced from UVCS observations. This suggests that the minor ions are heated by a different mechanism than protons.