2004A&A...415.1079A

We gathered long-term multicolour Geneva UB₁BB₂V₁VG photometric and high-resolution (R=40000) spectroscopic data of the two γDoradus stars HD12901 and HD48501. The photometry reveals three frequencies for each of the two stars: f₁=1.21563c/d, f₂=1.39594c/d and f₃=2.18636c/d for HD12901 and f₁=1.09408c/d, f₂=1.29054c/d and f₃=1.19924c/d for HD48501. The photometric amplitude is each time largest in the Geneva B₁ filter and the variations in all the different filters are perfectly in phase within the measurement errors. Mode identification points out that the six modes are all l=1 modes and that the non-adiabatic temperature variations are extremely small, in contradiction to current theoretical predictions. Our spectra show that all the observed frequencies are intrinsic to the stars and cannot be due to binarity. We detect clear line-profile variations at low amplitude (<1km/s) due to the oscillations of both targets. The estimated vsin i from the spectra are ∼53km/s for HD12901 and ∼29km/s for HD48501. It is at present unclear if the triplet-like structure for HD48501 is the consequence of rotational splitting or of the large separation expected for high-order gravity modes in the asymptotic regime.