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 ^ { 13 } CO and C ^ { 18 } O J =2–1 transitions permits a measurement of the total stellar mass in this system , 5.29 \pm 0.09 M _ { \odot } , and the circum-triple disk inclination , 137.6 \pm 2.0 \degr .
Optical spectra spanning a 35 year period were used to derive new radial velocities and , coupled with a spectroscopic disentangling technique , revealed that the A and B components of GW Ori form a double-lined spectroscopic binary with a 241.50 \pm 0.05 day period ; a tertiary companion orbits that inner pair with a 4218 \pm 50 day period .
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 _ { \mathrm { A } } \approx 2.7 M _ { \odot } , M _ { \mathrm { B } } \approx 1.7 M _ { \odot } , M _ { \mathrm { C } } \approx 0.9 M _ { \odot } ) and find strong evidence that at least one ( and likely both ) stellar orbital planes are misaligned with the disk plane by as much as 45 \degr .
A V -band light curve spanning 30 years reveals several new \sim 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 GW Ori system is \sim 1 Myr old .