Observation of quasi-continuum line emission from Fe VII to Fe X in the extreme-ultraviolet region below 140 angstrom

The line emission of Fe vn-Fe x ions in the extreme-ultraviolet region belo w 140 Angstrom was measured in controlled laboratory experiments under cond itions representative of stellar coronae. The observations are compared wit h predictions from standard spectral models using the CHIANTI and MEKAL ato mic databases. We find that the atomic databases miss most of the line flux in this region. While some of the missing lines form isolated features, mo st add up to form a quasi continuum in the 60-120 Angstrom region. This inc ompleteness can explain the poor fit when applying global-fitting technique s to spectra from cool stars measured by the Extreme-Ultraviolet Explorer s atellite, the origin of which has been a source of controversy since the or iginal observations were made.