Intrinsic photometric characterisation of stellar oscillations and granulation. Solar reference values and CoRoT response functions

TL;DR

This paper develops response functions to convert photometric measurements of stellar oscillations and granulation into intrinsic values, enabling consistent comparisons across different instruments and bandpasses, with applications to solar and CoRoT data.

Contribution

It introduces a method to derive intrinsic oscillation and granulation amplitudes from photometry, accounting for instrument and bandpass effects, and provides reference values for the Sun and CoRoT observations.

Findings

Good agreement of results across different datasets

Established solar reference intrinsic values

Derived simple analytic response functions for CoRoT

Abstract

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.