Intrinsic photometric characterisation of stellar oscillations and granulation
Solar reference values and CoRoT response functionsE. Michel1, R. Samadi1, F. Baudin2, C. Barban1, T. Appourchaux2, and M. Auvergne1
1 Observatoire de Paris-LESIA, CNRS (UMR 8109), Université Pierre et Marie Curie, Université Denis Diderot, Pl. J. Janssen, 92195 Meudon, France
2 Institut d'Astrophysique Spatiale, UMR8617, Université Paris X, Bât.121, 91405 Orsay, France
Received 9 June 2008 / Accepted 6 December 2008
Context. Measuring amplitudes of solar-like oscillations and the granulation power spectral density constitute two promising sources of information to improve our understanding and description of the convection in outer layers of stars. However, different instruments, using different techniques and different bandpasses, give measurements that cannot be directly compared to each other or to theoretical values.
Aims. In this work, we define simple response functions to derive intrinsic oscillation amplitudes and granulation power densities, from photometry measurements obtained with a specific instrument on a specific star.
Methods. We test this method on different photometry data sets obtained on the Sun with two different instruments in three different bandpasses.
Results. We show that the results are in good agreement and we establish reference intrinsic values for the Sun with photometry. We also compute the response functions of the CoRoT instrument for a range of parameters representative of the Main Sequence solar-like pulsators to be observed with CoRoT. We show that these response functions can be conveniently described by simple analytic functions of the effective temperature of the target star.
Key words: Sun: oscillations -- Sun: granulation -- stars: oscillations -- techniques: photometric -- convection
© ESO 2009