We report on new high-resolution imaging and spectroscopy on the multiple T Tauri star system V773 Tau over the 2003 – 2009 period .
With these data we derive relative astrometry , photometry between the A and B components , and radial velocity ( RV ) of the A-subsystem components .
Combining these new data with previously published astrometry and RVs , we update the relative A-B orbit model .
This updated orbit model , the known system distance , and A subsystem parameters yields a dynamical mass for the B component for the first time .
Remarkably the derived B dynamical mass is in the range of 1.7 – 3.0 M _ { \sun } .
This is much higher than previous estimates , and suggests that like A , B is also a multiple stellar system .

Among these data , spatially-resolved spectroscopy provide new insight into the nature of the B component .
Similar to A , these near-IR spectra indicate that the dominant source in B is of mid-K spectral type .
If B is in fact a multiple star system as suggested by the dynamical mass estimate , the simplest assumption is that B is composed of similar \sim 1.2 M _ { \sun } PMS stars in a close ( < 1 AU ) binary system .
This inference is supported by line-shape changes in near-IR spectroscopy of B , tentatively interpreted as changing RV among components in V773 Tau B .

Relative photometry indicate that B is highly variable in the near-IR .
The most likely explanation for this variability is circum-B material resulting in variable line-of-sight extinction .
The distribution of this material must be significantly affected by both the putative B multiplicity , and the A-B orbit .