Young and eccentric: the quadruple system HD 86588

TL;DR

This study reveals HD 86588 as a young, quadruple star system with complex hierarchical structure, detailed orbital characteristics, and evidence of recent dynamical interactions influencing its eccentricity and evolution.

Contribution

The paper provides the first detailed characterization of the quadruple system HD 86588, including its hierarchical structure, orbital parameters, and insights into its dynamical history and age.

Findings

HD 86588 is a quadruple system with a 3-tier hierarchy.

The inner binary Aa,Abc has a short, eccentric orbit with no eclipses.

The system is younger than 150 Myr and likely influenced by recent dynamical interactions.

Abstract

High-resolution spectroscopy and speckle interferometry reveal the young star HD 86588 as a quadruple system with a 3-tier hierarchy. The 0.3" resolved binary A,B with an estimated period around 300 years contains the 8-year pair Aa,Abc (also potentially resolvable), where Ab,Ac is a double-lined binary with equal components, for which we compute the spectroscopic orbit. Despite the short period of 2.4058 day, the orbit of Ab,Ac is eccentric (e=0.086+-0.003). It has a large inclination, but there are no eclipses; only a 4.4 mmag light modulation apparently caused by star spots on the components of this binary is detected with Evryscope. Assuming a moderate extinction of A_V = 0.5 mag and a parallax of 5.2 mas, we find that the stars are on or close to the main sequence (age >10 Myr) and their masses are from 1 to 1.3 solar. We measure the strength of the Lithium line in the visual secondary B which, together with rotation, suggests that the system is younger than 150 Myr. This object is located behind the extension of the Chamaeleon I dark cloud (which explains extinction and interstellar Sodium absorption), but apparently does not belong to it. We propose a scenario where the inner orbit has recently acquired its high eccentricity through dynamical interaction with the outer two components; it is now undergoing rapid tidal circularization on a time scale of ~1 Myr. Alternatively, the eccentricity could be excited quasi-stationary by the outer component Aa.