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Session 36 - Solar Activity.
Display session, Tuesday, June 11
Helium lines are generally a valuable tool to trace activity in the solar atmosphere. The most prominent lines observable from ground-based observatories are the triplet lines at 587.6 and 1083 nm, but despite the wide use of these activity tracer (especially of the latter), little progress has been made towards the exploitation of their diagnostic potential. However, recent theoretical investigations have pointed out that of correlation between the two main triplet He I lines can discriminate between different scenarios of the line formation, ultimately giving informations on the structure of the upper chromosphere/lower transition region. The observations presented here address such issues for the first time. The spectra were obtained with the FTS at the McMath/Pierce telescope on Kitt Peak; they constitute in fact a set of simultaneous observations of the two lines for several solar features. The observed joint response of \lambda587.6 and \lambda1083 to the level of chromospheric heating can thus be directly compared with theoretical predictions.
Program listing for Tuesday