A young spectroscopic binary in a quintuple system part of the Local Association

TL;DR

This study characterizes a young spectroscopic binary GJ1284 within a quintuple system, deriving its orbital and physical parameters, revising its group membership, and comparing observational data with stellar evolution models to understand its age and mass.

Contribution

It provides detailed orbital and physical parameters of GJ1284, revises its membership in a young moving group, and compares observational data with multiple stellar evolution models, highlighting discrepancies and the role of magnetic activity.

Findings

GJ1284 is a young binary system at ~16 pc with an eccentric orbit of 11.83 days.

The system's age is estimated between 110-800 Myr based on kinematics and activity indicators.

Mass estimates from models are inconsistent with photometry, except for PARSEC, suggesting model limitations.

Abstract

Double-lined spectroscopic binaries (SB2) allow us to determine a lower limit of the masses of their components directly to test stellar models. In this work, our aim is to derive the orbital and physical parameters of GJ1284, a young SB2. We also revise the membership of this system and its two wide co-moving companions, GJ898 and GJ897AB, to a young moving group to assess, along with other youth indicators, their age. Afterwards, we compare the results from these analyses and the photometry of these systems with several pre-main-sequence evolutionary models. We determine the orbit of the GJ1284 system alongside its systemic velocity from high resolution spectra. Additionally, we use TESS photometry to derive the rotational period of the GJ1284 and its two wide companions. GJ1284 is a binary system located at approximately 16 pc with an eccentric orbit ($ e = 0.505 $) of 11.83 d period made up of an M2-M2.5 + M3-M3.5. The revised systemic velocity of $ \gamma = 0.84 \pm 0.14\,\mathrm{km\,s}^{-1} $ suggests that it is a member of the Local Association. The kinematics together with other activity and youth indicators imply an age of 110-800 Myr for this system and its two companions. The isochronal ages derived from the comparison of the photometry with several evolutionary models are younger than the age estimated from the activity indicators for the three co-moving systems. The masses for the components of GJ1284, derived from their luminosity and age using the different models, are not consistent with the masses derived from the photometry, except for the PARSEC models, but are compatible with dynamical masses of double-lined eclipsing binaries with similar ages and spectral types. The effect of magnetic activity in the form of spots can reconcile to some extent the photometric and dynamical masses, but is not considered in most of the evolutionary models.