HII 2407: A Low-Mass Eclipsing Binary Revealed by K2 Observations of the Pleiades

TL;DR

This paper reports the discovery and analysis of HII 2407 as a low-mass eclipsing binary in the Pleiades, providing new constraints on stellar parameters and evolutionary models.

Contribution

It identifies HII 2407 as an eclipsing binary using K2 data and derives its orbital and stellar parameters, including the pre-main-sequence secondary.

Findings

Primary star is on the main sequence.

Secondary star is pre-main-sequence.

System is likely tidally synchronized.

Abstract

The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within $Kepler$/$K2$ photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main-sequence and we compare our results for the $M/M_\odot$ and $R/R_\odot$ values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.