Visibilities and bolometric corrections for stellar oscillation modes observed by Kepler

Context.Kepler produces a large amount of data used for asteroseismological analyses, particularly of solar-like stars and red giants. The mode amplitudes observed in the Kepler spectral band have to be converted into bolometric amplitudes to be compared to models. Aims. We give a simple bolometric correction for the amplitudes of radial modes observed with Kepler, as well as the relative visibilities of non-radial modes. Methods. We numerically compute the bolometric correction cK−bol and mode visibilities for different effective temperatures Teff within the range 4000–7500 K, using a similar approach to a recent one from the literature. Results. We derive a law for the correction to bolometric values: cK − bol = 1 + a1(Teff − To) + a2(Teff − To)2, with To = 5934 K, a1 = 1.349 × 10-4 K-1, and a2 = −3.120 × 10-9 K-2 or, alternatively, as the power law cK − bol = (Teff/To)α with α = 0.80. We give tabulated values for the mode visibilities based on limb-darkening (LD), computed from ATLAS9 model atmospheres for Teff ∈ [4000,7500] K, log g ∈ [2.5,4.5] , and [M/H] ∈ [ − 1.0, + 1.0] . We show that using LD profiles already integrated over the spectral band provides quick and good approximations for visibilities. We point out the limits of these classical visibility estimations.