The Architecture of the GW Ori Young Triple-star System and Its Disk: Dynamical Masses, Mutual Inclinations, and Recurrent Eclipses

We present spatially and spectrally resolved Atacama Large Millimeter/submillimeter Array (ALMA) observations of gas and dust orbiting the pre-main-sequence hierarchical triple-star system GW Ori. A forward modeling of the (CO)-C-13 and (CO)-O-18 J = 2-1 transitions permits a measurement of the total stellar mass in this system, 5.29 +/-. 0.09 M-circle dot, and the circumtriple disk inclination, 137 degrees.6 +/- 2 degrees.0. Optical spectra spanning a 35 yr period were used to derive new radial velocities and, coupled with a spectroscopic disentangling technique, revealed that the A and B components of GWOri form a double-lined spectroscopic binary with a period of 241.50 +/- 0.05 days; a tertiary companion orbits that inner pair with a period of 4218 +/- 50 days. Combining the results from the ALMA data and the optical spectra with three epochs of astrometry in the literature, we constrain the individual stellar masses in the system (M-A approximate to 2.7M(circle dot), M-B approximate to 1.7M(circle dot), M-C approximate to 0.9M(circle dot)) and find strong evidence that at least one of the stellar orbital planes (and likely both) is misaligned with the disk plane by as much as 45 degrees. A V-band light curve spanning 30 yr reveals several new similar to 30-day eclipse events 0.1-0.7. mag in depth and a 0.2 mag sinusoidal oscillation that is clearly phased with the AB-C orbital period. Taken together, these features suggest that the A-B pair may be partially obscured by material in the inner disk as the pair approaches apoastron in the hierarchical orbit. Lastly, we conclude that stellar evolutionary models are consistent with our measurements of the masses and basic photospheric properties if the GWOri system is similar to 1Myr old.