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The irradiation of close-in planets by their star influences their evolutionand might be responsible for a population of ultra-short period planets erodedto their bare core. In orbit around a bright, nearby G-type star, thesuper-Earth 55 Cnc e offers the possibility to address these issues through UVtransit observations. We used the Hubble Space Telescope to observe the transitin the FUV over 3 epochs in Apr. 2016, Jan. 2017, and Feb. 2017. Theseobservations reveal significant short- and long-term variability in 55 Cncchromospheric emission lines. In the last 2 epochs, we detected a larger fluxin the C III, Si III, and Si IV lines after the planet passed the approachingquadrature, followed by a flux decrease in the Si IV doublet. In the secondepoch these variations are contemporaneous with flux decreases in the Si II andC II doublet. All epochs show flux decreases in the N V doublet as well, albeitat different orbital phases. These flux decreases are consistent withabsorption from optically thin clouds of gas, are mostly localized at low andredshifted radial velocities in the star rest frame, and occur preferentiallybefore and during the transit. These 3 points make it unlikely that thevariations are purely stellar, yet we show that the occulting material is alsounlikely to originate from the planet. We tentatively propose that the motionof 55 Cnc e at the fringes of the stellar corona leads to the formation of acool coronal rain. The inhomogeneity and temporal evolution of the stellarcorona would be responsible for the differences between the visits. Additionalvariations are detected in the C II doublet in the first epoch and in the O Itriplet in all epochs with a different behavior that points toward intrinsicstellar variability. Further observations at FUV wavelengths are required todisentangle between star-planet interactions and the activity of the star

High-energy environment of super-Earth 55 Cnc e I: Far-UV chromospheric variability as a possible tracer of planet-induced coronal rain