2007A&A...464.1059L

The F5 IV-V star Procyon A (α-CMi) was observed in January 2001 by means of the high-resolution spectrograph SARG operating with the TNG 3.5m Italian telescope (Telescopio Nazionale Galileo) in the Canary Islands, exploiting the iodine cell technique. The time series of about 950 spectra carried out during 6 observation nights and a preliminary data analysis (Claudi et al., 2005A&A...429L..17C) showed a significant power excess between 0.5 and 1.5mHz, with ≃1m/s peak amplitude. Here we present a more detailed analysis of the time series, based on both radial velocity and line equivalent width analyses. From the power spectrum we found a typical p-mode frequency comb-like structure, identified 11 frequencies with a good margin of certainty in the interval 500-1400µHz of modes with l=0,1,2 and 7≤n≤22, and determined large and small frequency separations, Δν= 55.90±0.08µHz and δν₀₂=7.1±1.3µHz, respectively. The mean amplitude per mode (l=0,1) at peak power is 0.45±0.07m/s, twice larger than the solar one, and the mode lifetime is 2±0.4d, which indicates a non-coherent, stochastic source of mode excitation. Line equivalent width measurements do not show a significant excess in power in the examined spectral region but allowed us to infer an upper limit to the granulation noise.