A Search for Signatures of Preferential Heating by Ion Cyclotron Waves in the Low Corona

TitleA Search for Signatures of Preferential Heating by Ion Cyclotron Waves in the Low Corona
Publication TypeConference Paper
Year of Publication2004
AuthorsDolla, L., Solomon J., and Lemaire P.
EditorLacoste, H.
Conference NameSOHO 13 Waves, Oscillations and Small-Scale Transients Events in the Solar Atmosphere: Joint View from SOHO and TRACE
Date PublishedJan
Abstract

Pointing above the solar Poles (above the limb), in May 2002 (MEDOC Campaign #9), with the SUMER spectrometer (on board SOHO), we measure the width of several minor ion lines. Assuming the same so-called ''unresolved velocity'' for each ion, we derive the temperature of the ion species. We then investigate the possible presence of preferential heating of ions presenting a low charge-to-mass ratio, characteristic of ion cyclotron interaction. For a given altitude, the trend of the temperature as a function of the charge-to-mass ratio is difficult to interpret, due to the unknown value of . We get rid of that constraint by analysing the difference of line width with the altitude. Interpreted in terms of difference in temperature only, it is independent of the absolute value of the temperature, or of the unresolved velocity. Nevertheless, one could interpret, to a certain extent, the difference in line width as an increase of the unresolved velocity with altitude. We conclude that our results support the possibility of a preferential ion cyclotron heating.