Determine whether β Aurigae has a distant tertiary companion

Determine whether the eclipsing binary β Aurigae has a distant tertiary stellar companion that is not detected in the available radial-velocity, interferometric, or eclipse-timing data.

Background

The analysis models β Aurigae as a Keplerian two-body system and reports no observational indication of an additional component. Nevertheless, the available data do not formally exclude a distant tertiary companion. Establishing whether such a companion exists would require additional observations or a dedicated search for long-term dynamical, spectroscopic, astrometric, or eclipse-timing signatures.

References

In our model, a Keplerian orbit of two bodies with constant parameters was assumed. Though the existence of a distant tertiary cannot be formally rejected, we found no indication in the data supporting its presence. In particular, the work of \citet{Southworth2007} already detected no third light even at the mmag-precision of the WIRE data, and neither the RV residuals nor the interferometry measurements indicate an additional component.

— Interferometric Survey of Stellar Parameters: Mass of the metallic A-type binary $β$ Aur  (2609.03886 - Jonák et al., 3 Sep 2026) in Discussion, subsection “Model approximations and agreement”