The Detached Eclipsing Binary KV29 and the Age of the Open Cluster M11

TL;DR

This study uses detailed observations of the detached eclipsing binary KV29 in open cluster M11 to precisely determine the cluster's age at approximately 222 million years, providing key insights into stellar evolution.

Contribution

It presents new, precise measurements of binary star parameters in M11, constraining the cluster's age with improved accuracy using the primary star’s radius.

Findings

Cluster age estimated at 222 Myr with uncertainties.

Masses and radii of binary components measured accurately.

Binary membership confirmed through multiple evidence.

Abstract

We present an extensive set of photometry and radial velocities for the detached eclipsing binary KV 29 in the intermediate-aged open cluster M11 (NGC 6705). Spectroscopy shows that the system is double-lined and all available evidence (proper motion, photometry, and position on the CMD) indicates it is a member of the cluster. We find the period of the binary to be $4.64276\pm0.00001$ days. We find masses $3.604^{+0.002}_{-0.011}M_\odot$ and $1.837^{+0.001}_{-0.006}M_\odot$, and radii $5.392^{+0.018}_{-0.035}R_\odot$ and $1.656^{+0.007}_{-0.044}R_\odot$ for the primary and secondary stars, respectively. Because the primary star in the binary is rapidly evolving and is brighter than the cluster turnoff in a color-magnitude diagram, the measurement of its radius leads to a strong constraint on the cluster age. We find the age of M11 to be $222^{+2}_{-3}\pm15$ Myr, where the quoted uncertainties come from statistical errors in the calculated masses and radii, and systematic uncertainties due to the ambiguity of the metallicity of the open cluster and variations within the isochrone models concerning heavy elements and convective overshooting.