A Coplanar Circumbinary Protoplanetary Disk in the TWA 3 Triple M Dwarf System

Abstract We present sensitive ALMA observations of TWA 3, a nearby, young (?10 Myr) hierarchical system composed three pre-main-sequence M3–M4.5 stars. For the first time, we detected 12 CO and 13 J = 2–1 emissions from circumbinary protoplanetary disk around 3A. jointly fit velocity field, stellar astrometric positions, radial velocities to infer architecture system. The Aa Ab stars (0.29 ± 0.01 M ? 0.24 , respectively) comprising tight ( P 35 days) eccentric e 0.63 0.01) spectroscopic binary are coplanar with their (misalignment <6° 68% confidence), similar other short-period systems. From models spectral energy distribution, found inner radius r 0.50–0.75 au) be consistent theoretical predictions dynamical truncation cav / ? 3. outer orbit tertiary star B (0.40 0.28 ? 65 18 au, 0.3 0.2) is not as well constrained orbit; however, orbits A still preferred < 20°). To better understand influence on 3A disk, performed SPH simulations that edge gas 8.5 0.2 most coplanar, circular, or moderately orbit, supporting preference joint orbital fit.