Orbital Solution for the Spectroscopic Binary in the GW Ori Hierarchical Triple

TL;DR

This paper reports the first double-lined orbital solution for the close binary in the GW Ori triple system, revealing detailed orbital parameters, component masses, and spectral types through infrared spectroscopy, and contributing to understanding of young stellar systems.

Contribution

It provides the first infrared double-lined orbital solution for GW Ori's binary, including mass ratio, orbital parameters, and individual stellar masses, advancing knowledge of this young triple system.

Findings

Detected both stars' lines in infrared spectra.

Derived orbital parameters: period, eccentricity, mass ratio.

Estimated individual stellar masses and coeval age.

Abstract

We present the first double-lined orbital solution for the close binary in the GW Ori triple system. Using 12 epochs of infrared spectroscopy, we detected the lines of both stars in the inner pair, previously known as single-lined only. Our preliminary infrared orbital solution has an eccentricity of e = 0.21 +/- 0.10, a period of P = 241.15 +/- 0.72 days, and a mass ratio of q = 0.66 +/- 0.13. We find a larger semi-amplitude for the primary star, K1 = 6.57 +/- 1.00 km s^-1, with an infrared-only solution compared to K1 = 4.41 +/- 0.33 km s^-1 with optical data from the literature, likely the result of line blending and veiling in the optical. The component spectral types correspond to G3 and K0 stars, with vsini values of 43 km s^-1 and 50 km s^-1, respectively. We obtained a flux ratio of alpha = 0.58 +/- 0.14 in the H-band, allowing us to estimate individual masses of 3.2 and 2.7 M_sun for the primary and secondary, respectively, using evolutionary tracks. The tracks also yield a coeval age of 1 Myr for both components to within 1 sigma. GW Ori is surrounded by a circumbinary/circumtriple disk. A tertiary component has been detected in previous studies; however, we did not detect this component in our near-infrared spectra, probably the result of its relative faintness and blending in the absorption lines of these rapidly rotating stars. With these results, GW Ori joins the small number of classical T Tauri, double-lined spectroscopic binaries.