Fe XIII DENSITY DIAGNOSTICS IN THE EIS OBSERVING WAVELENGTHS

The diagnostic capability of Fe XIII line features seen in the 170-210 angstrom waveband of the EUV Imaging Spectrometer (EIS) on Hinode is investigated, with emphasis on density diagnostics applied to solar active regions. Four diagnostic line pairs are found to yield consistent densities ranging from 10(8.5) to 10(9.5) cm(-3) across an active region using a new theoretical model of the ion. In separate EIS observations of a small flare, the widely used line pair, Fe XIII lambda 203.8/lambda 202.0, is found to reach the high density limit predicted by a new theoretical model of the iron ion.