Evidence of Jovian acoustic global modes

We report the detection of global acoustic modes on Jupiter and measurement of its fundamental frequency. The observations have been obtained thanks to the instrument SYMPA [2], a specially designed instrument able to produce Doppler velocity maps of the visible surface of Jupiter and monitor small variations in time. We will describe briefly the principal of the instrument, the observations and the performances. We will focus this presentation on the data processing and the results. After a treatment adapted to the instrument [1] to produce the time series for each modes, we applied a procedure widely used in asteroseismology in order to detect the signature of possible global modes. A clear excess of power is present in the frequency range where the Jovian modes are expected in the Power Density Spectrum of the time series corresponding to the l=1 modes, and the measured amplitude is compatible with theoretical expectations for acoustic modes.