On the electron temperatures, densities and hot ions in coronal hole plasma observed by SUMER on SOHO Original Research Article

Making use of high-resolution ultraviolet observations obtained with SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on the spacecraft SOHO (Solar and Heliospheric Observatory), we study plasma temperatures, densities and hot ions in polar coronal holes (source region of the high-speed solar wind). In particular, we present spectroscopic diagnostics for Ne viii, Mg viii, Si viii, and Mg ix lines to infer these physical parameters and discuss the constraints of their applications in the coronal hole plasma. We also present the implications of this investigation in addressing the acceleration mechanisms of the solar wind, one of the outstanding problems in solar physics.