The Interior Structure Constants as an Age Diagnostic for Low-Mass, Pre-Main Sequence Detached Eclipsing Binary Stars

TL;DR

This paper introduces a new method to determine the ages of low-mass pre-main sequence binary stars by analyzing their apsidal motion, which reflects their internal structure and contraction stage, providing an age estimate insensitive to surface activity effects.

Contribution

The paper proposes a novel age diagnostic technique based on apsidal motion and interior structure constants, applicable to low-mass pre-main sequence stars, enhancing age determination accuracy.

Findings

Interior structure constants change rapidly during radiative core contraction.

The method provides age estimates with 5-10% precision.

Potential for application with current and future time domain missions.

Abstract

We propose a novel method for determining the ages of low-mass, pre-main sequence stellar systems using the apsidal motion of low-mass detached eclipsing binaries. The apsidal motion of a binary system with an eccentric orbit provides information regarding the interior structure constants of the individual stars. These constants are related to the normalized stellar interior density distribution and can be extracted from the predictions of stellar evolution models. We demonstrate that low-mass, pre-main sequence stars undergoing radiative core contraction display rapidly changing interior structure constants (greater than 5% per 10 Myr) that, when combined with observational determinations of the interior structure constants (with 5 -- 10% precision), allow for a robust age estimate. This age estimate, unlike those based on surface quantities, is largely insensitive to the surface layer where effects of magnetic activity are likely to be most pronounced. On the main sequence, where age sensitivity is minimal, the interior structure constants provide a valuable test of the physics used in stellar structure models of low-mass stars. There are currently no known systems where this technique is applicable. Nevertheless, the emphasis on time domain astronomy with current missions, such as Kepler, and future missions, such as LSST, has the potential to discover systems where the proposed method will be observationally feasible.