Precise surface gravities of $\delta$ Scuti stars from asteroseismology

TL;DR

This study demonstrates that high-precision photometry and parallax measurements can accurately determine the surface gravities of $\delta$ Sct stars, refining the $\Delta u-ar ho$ relation and eliminating the need for spectroscopic constraints.

Contribution

It refines the $\Delta u-ar ho$ relation for $\delta$ Sct stars and shows that surface gravities can be accurately derived from asteroseismology and parallaxes alone.

Findings

Good agreement with traditional spectroscopic and binary analysis results.

Validates $\Delta u$ as a key observable for $\delta$ Sct stars.

Settles the degeneracy problem in $\log g$ determination.

Abstract

The work reported here demonstrates that it is possible to accurately determine surface gravities of $\delta$ Sct stars using the frequency content from high precision photometry and a measurement of the parallax. Using a sample of 10 eclipsing binary systems with a $\delta$ Sct component and the unique $\delta$ Sct star discovered with a transiting planet, WASP-33, we were able to refine the $\Delta\nu-\bar\rho$ relation. Using this relation and parallaxes, we obtained independent values for the masses and radii, allowing us to calculate the surface gravities without any constraints from spectroscopic or binary analysis. A remarkably good agreement was found between our results and those published, extracted from the analysis of the radial velocities and light curves of the systems. This reinforces the potential of $\Delta\nu$ as a valuable observable for $\delta$ Sct stars and settles the degeneracy problem for the $\log g$ determination through spectroscopy.