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Paper: Ion Temperatures in the Low Solar Corona: Polar Coronal Holes at Solar Minimum
Volume: 428, SOHO-23: Understanding a Peculiar Solar Minimum
Page: 197
Authors: Landi, E.; Cranmer, S. R.
Abstract: We use a SUMER spectrum of a polar coronal hole to measure the ion temperatures Ti of many ions between 0.03 and 0.17 Rsun above the limb. We find that the measured Ti are almost always larger than the electron temperatures (Te) and exhibit a non-monotonic dependence on the charge-to-mass ratio. We use these measurements to provide empirical constraints to a theoretical model of ion heating and acceleration based on gradually replenished ion-cyclotron waves and anisotropic magnetohydrodynamic turbulence. We find that the empirical heating model and the turbulent cascade model agree with one another and with observations for charge-to-mass (Z/A) ratios smaller than about 0.25. Ions with Z/A > 0.25 disagree with the model.
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