Temperature and density structures of solar corona - A test of iron line diagnostic capability of EIS instrument on board Hinode

Increased diagnostic capability of the EUV Imaging Spectrometer (EIS) aboard Hinode (former Solar-B) has been demonstrated with a set of iron emission lines emerging in the two EIS observing wavelength bands (170-210 angstrom and 250-290 angstrom) and their line-intensity ratios. Abundance-uncertainty free relative emission measure distributions as a function of temperature were deduced using only iron emission lines of various ionization stages. First-light spectra of a small active region show iron lines ranging from Fe VIII (185.2 angstrom and 186.6 angstrom) through Fe XVII (204.7 angstrom, 254.9 angstrom, and 269.4 angstrom). Spectra of a C-class flare confirms the presence of one of these higher temperature lines (Fe XVII at 254.9 angstrom) more clearly, as well showing Fe XXIV (192.0 angstrom and 255.1 angstrom) and Fe XXIII (263.8 angstrom), which are normally only seen at flare temperatures.