Modelling low charge ions in the solar transition region

Roger Dufresne

Hosted by University of Cambridge, United Kingdom on September 7, 2023


Developing models for line emission in the solar transition region has been overlooked in comparison to the chromosphere and corona. As a result, theoreticians and observers tend to use coronal modelling for this region because of its relative simplicity, especially in large scale simulations. Coronal modelling, however, can produce significant discrepancies compared to observations of transition region lines. The present work improves on coronal modelling by including atomic processes which become relevant in the cooler parts of the atmosphere. These include the influences of electron density, solar radiation field and collisions with hydrogen and helium. Results from the new models are compared with ion balances from the coronal modelling available in CHIANTI. The new data is also used to calculate line intensities, and comparison with average quiet sun observations of the transition region show clear improvements in predicted emission. Work is currently underway to include the new modelling in CHIANTI.

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