Probing central stellar regions with a new indicator based on the inversion of frequency ratios

In the last decade, astonishing progresses were achieved in asteroseismology thanks to the high-quality data from the space-based missions CoRoT, Kepler and TESS and the field will further prosper with the future PLATO mission.

This high precision is however limited by the “so-called” surface effects of solar-like oscillations. Despite several attempts (Kjeldsen et al. 2008, Ball & Gizon 2014, Sonoi et al. 2015, Ball et al. 2016), current approaches remain empirical and constitute a weakness in stellar modelling and inversion techniques. As illustrated in Buldgen et al. (2019) and Bétrisey et al. (2021, submitted), their actual implementation shows biases on the estimated stellar parameters.

For this reason, we developed a new indicator based on the inversion of frequency ratios instead of individual frequencies as it is currently done. This approach is motivated by the works of Roxburgh & Voronsov (2003) and Oti et al. (2005) who pointed out that these frequency ratios and their corresponding kernels are not sensitive to surface regions. In contrast, they are sensitive to deeper stellar layers. Therefore, our new indicator seems promising to better probe central stellar regions of intermediate-mass stars.