Coronal radiation and helium lambda 584 emission in active regions

Based on EUV observations of eleven sunspot regions obtained with the Coron al Diagnostic Spectrometer, CDS, on SOHO we have studied the spatial distri bution, temporal variation and wavelength shift of the He I lambda 584 line . We find a relatively high spatial correlation between the coronal line Fe XVI lambda 360 and the He I lambda 584 line. This points to coronal back-r adiation as an important contributor to the formation of the He I line in a ctive regions. However, contribution to the line formation from another sou rce is suggested by the following two findings: First, the red-shifted line profiles of both He I lambda 584 and the transition region lines tend to b e more intense than blue-shifted profiles. Second, the He I lambda 584 emis sion changes significantly faster than the coronal line emission.