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Penumbral transient brightening events have been attributed to magneticreconnection episodes occurring in the low corona. We investigated the triggermechanism of these events in active region NOAA 12546 by using multi-wavelengthobservations obtained with the Interferometric Bidimensional Spectrometer(IBIS), by the \textit{Solar Dynamics Observatory} (SDO), the \textit{InterfaceRegion Imaging Spectrograph} (IRIS), and the \textit{Hinode} satellites. Wefocused on the evolution of an area of the penumbra adjacent to two small-scaleemerging flux regions (EFRs), which manifested three brightening eventsdetected from the chromosphere to the corona. Two of these events correspond toB-class flares. The same region showed short-lived moving magnetic features(MMFs) that streamed out from the penumbra. In the photosphere, the EFRs led tosmall-scale penumbral changes associated with a counter-Evershed flow and to areconfiguration of the magnetic fields in the moat. The brightening events hadone of the footpoints embedded in the penumbra and seemed to result from thedistinctive interplay between the pre-existing penumbral fields, MMFs, and theEFRs. The \textit{IRIS} spectra measured therein reveal enhanced temperatureand asymmetries in spectral lines, suggestive of event triggering at differentheight in the atmosphere. Specifically, the blue asymmetry noted in \ion{C}{2}and \ion{Mg}{2} h\&k lines suggests the occurrence of chromospheric evaporationat the footpoint located in the penumbra as a consequence of magneticreconnection process at higher atmospheric heigths.

Penumbral brightening events observed in AR NOAA 12546