Comprehensive stellar seismic analysis

New method exploiting the glitches information in solar-like pulsators

¹ Institut d’Astrophysique et Géophysique de l’Université de Liège, Allée du 6 août 17, 4000 Liège, Belgium
e-mail: martin.farnir@uliege.be
² School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Received: 8 August 2018
Accepted: 10 December 2018

Abstract

Aims. We develop a method that provides a comprehensive analysis of the oscillation spectra of solar-like pulsators. We define new seismic indicators that should be as uncorrelated and as precise as possible and should hold detailed information about stellar interiors. This is essential to improve the quality of the results obtained from asteroseismology as it will provide better stellar models which in turn can be used to refine inferences made in exoplanetology and galactic archaeology.

Methods. The presented method – WhoSGlAd – relies on Gram-Schmidt’s orthogonalisation process. A Euclidean vector sub-space of functions is defined and the oscillation frequencies are projected over an orthonormal basis in a specific order. This allowed us to obtain independent coefficients that we combined to define independent seismic indicators.

Results. The developed method has been shown to be stable and to converge efficiently for solar-like pulsators. Thus, detailed and precise inferences can be obtained on the mass, the age, the chemical composition and the undershooting in the interior of the studied stars. However, attention has to be paid when studying the helium glitch as there seems to be a degeneracy between the influence of the helium abundance and that of the heavy elements on the glitch amplitude. As an example, we analyse the 16CygA (HD 186408) oscillation spectrum to provide an illustration of the capabilities of the method.