Absolute properties of the highly eccentric eclipsing binary star LV Herculis

TL;DR

This study provides detailed measurements of the masses, radii, temperatures, and metallicity of the highly eccentric eclipsing binary LV Her, and compares these with stellar evolution models to estimate its age and tidal evolution state.

Contribution

First detailed characterization of the highly eccentric binary LV Her with precise stellar parameters and analysis of its tidal evolution and stellar model consistency.

Findings

Masses and radii determined with <1% error

Stellar evolution models fit the data for 3.8-4.2 Gyr age

Tidal evolution analysis suggests aligned spin axes and pseudo-synchronized rotation

Abstract

We report extensive spectroscopic and differential V-band photometric observations of the 18.4-day detached double-lined eclipsing binary LV Her (F9V), which has the highest eccentricity (e = 0.613) among the systems with well-measured properties. We determine the absolute masses and radii of the components to be M1 = 1.193 +/- 0.010 M(Sun), M2 = 1.1698 +/- 0.0081 M(Sun), R1 = 1.358 +/- 0.012 R(Sun), and R2 = 1.313 +/- 0.011 R(Sun), with fractional errors of 0.9% or better. The effective temperatures are 6060 +/- 150 K and 6030 +/- 150 K, respectively, and the overall metallicity is estimated to be [m/H] = +0.08 +/- 0.21. A comparison with current stellar evolution models for this composition indicates an excellent fit for an age between 3.8 and 4.2 Gyr, with both stars being near the middle of their main-sequence lifetimes. Full integration of the equations for tidal evolution is consistent with the high eccentricity, and suggests the stars' spin axes are aligned with the orbital axis, and that their rotations should be pseudo-synchronized. The latter prediction is not quite in agreement with the measured projected rotational velocities.