The orbit and stellar masses of the archetype colliding-wind binary WR 140

TL;DR

This paper refines the orbital parameters and stellar masses of the WR 140 binary system using new radial velocity and astrometric data, and discusses its evolutionary history based on stellar wind mass loss.

Contribution

It provides updated orbital elements and stellar masses for WR 140, incorporating new measurements and analyzing its evolution with BPASS models.

Findings

Stellar masses: WR star ~10.3 M_sun, O star ~29.3 M_sun.

New orbital measurements from radial velocities and astrometry.

Evolutionary analysis suggests wind-driven mass loss as the main formation process.

Abstract

We present updated orbital elements for the Wolf-Rayet (WR) binary WR\,140 (HD\,193793; WC7pd + O5.5fc). The new orbital elements were derived using previously published measurements along with {\color{black}160} new radial velocity measurements across the 2016 periastron passage of WR 140. Additionally, four new measurements of the orbital astrometry were collected with the CHARA Array. With these measurements, we derive stellar masses of $M_{\rm WR} = 10.31\pm0.45 M_\odot$ and $M_{\rm O} = 29.27\pm1.14 M_{\odot}$. We also include a discussion of the evolutionary history of this system from the Binary Population and Spectral Synthesis (BPASS) model grid to show that this WR star likely formed primarily through mass loss in the stellar winds, with only a moderate amount of mass lost or transferred through binary interactions.