Quasi-Periodic Fluctuations and Chromospheric Evaporation in a Solar Flare Ribbon Observed by Hinode/EIS, IRIS, and RHESSI

Abstract: The Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS) obtained rapid cadence (11.2 s) EUV stare spectra of an M7.3 flare ribbon in AR 12036 on 2014 April 18. Quasi-periodic (P approx. = 75.6 +/- 9.2 s) intensity fluctuations occurred in emission lines of O IV, Mg VI, Mg VII, Si VII, Fe XIV, and Fe XVI during the flare’s impulsive rise, and ended when the maximum intensity in Fe XXIII was reached. The profiles of the O IV- Fe XVI lines reveal that they were all redshifted during most of th…