Observation of linear polarization in the infrared CaII triplet lines during umbral flashes

We report on Telescope Heliographique pour l'Etude du Magnetisme et des Ins tabilites Solaires (THEMIS)(2) observations of linear polarization events a ssociated with umbral flashes observed in the Ca II infrared (IR) triplet l ines. The observed signals are usually delayed in time and shifted in space when compared to the intensity and circular polarization signals from the flash. The observations are compatible with a scenario whereby flashes are produced by a perturbation propagating along the magnetic held lines as the y bend out toward the penumbra. Only a fraction of the resolution element a ppears to be emitting flashlike profiles, as if the waves were propagating only within localized magnetic field lines. This localization, however, doe s not impede the apparent propagation of the perturbation horizontally with in the umbra.