New EUV Fe ix emission line identifications from hinode/eis

Abstract

Four Feix transitions in the wavelength range 188-198 å are identified for the first time in spectra from the EUV Imaging Spectrometer on board the Hinode satellite. In particular the emission line at 197.86 å is unblended and close to the peak of the EIS sensitivity curve, making it a valuable diagnostic of plasma at around 800,000 K -a critical temperature for studying the interface between the corona and transition region. Theoretical ratios among the four lines predicted from the CHIANTI database reveal weak sensitivity to density and temperature with observed values consistent with theory. The ratio of?197.86 relative to the λ 171.07 resonance line of Feix is found to be an excellent temperature diagnostic, independent of density, and the derived temperature in the analyzed data set is log T=5.95, close to the predicted temperature of maximum ionization of Fe ix. ©2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A.