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Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation\udmodes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way,\udp-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type\udand cooler.\udAims. We observed a B0IVe star, HD51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution,\udground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra\udavailable in the BeSS database.\udMethods. We analyzed the CoRoT and spectroscopic data with several methods: Clean-NG, FreqFind, and a sliding window method.\udWe also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation\udin the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the\udresults.\udResults. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d−1. The main frequencies\udare also recovered in the spectroscopic data. In particular we find that HD51452 undergoes gravito-inertial modes that are not in the\uddomain of those excited by the κ-mechanism. We propose that these are stochastic modes excited in the convective zones and that\udat least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically\udexcited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be\udundetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD51452 because of the very rapid stellar rotation.\udIn addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts.\udConclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD51452, which are stochastically excited\udgravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot\udBe stars.ANR (SIROCO)PRIN-INAF 2010Programa Nacional de Astronomía y Astrofísica - contrato AYA2010-18352Programa Nacional de Astronomía y Astrofísica - contrato AYA2010-20982-CO2-01F.R.S.-FNR

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452