A Subarcsecond Companion to the T Tauri Star AS 353B

Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the Subaru Telescope shows that it is a hierarchical triple system. The secondary component, located 5.″6 south of AS 353A, is resolved into a subarcsecond binary, AS 353 Ba and Bb, separated by 0.″24. Resolved spectroscopy of the two close components shows that both have nearly identical spectral types of about M1.5. Whereas AS 353A and Ba show clear evidence of an infrared excess, AS 353 Bb does not. We discuss the possible role of multiplicity in launching the large Herbig-Haro flow associated with AS 353A.