We present new orbital measurements of the pre-main sequence triple system , V807 Tau , using adaptive optics imaging at the Keck Observatory .
We computed an orbit for the close pair , V807 Tau Ba - Bb , with a period of 12.312 \pm 0.058 years and a semi-major axis of 38.59 \pm 0.16 mas .
By modeling the center of mass motion of the components in the close pair relative to the wide component , V807 Tau A , we measured a mass ratio of 0.843 \pm 0.050 for Bb/Ba .
Combined with the total mass from the relative orbit , we derived individual masses of M _ { Ba } = 0.564 \pm 0.018 ~ { } ( \frac { d } { 140 pc } ) ^ { 3 } M _ { \odot } and M _ { Bb } = 0.476 \pm 0.017 ~ { } ( \frac { d } { 140 pc } ) ^ { 3 } M _ { \odot } at an average distance of 140 pc to the Taurus star forming region .
We computed spectral energy distributions to determine the luminosities of the three components .
We also measured their spectral types , effective temperatures , and rotational velocities based on spatially resolved spectra obtained at the Keck Observatory .
If the rotational axes are aligned , then the projected rotational velocities imply that V807 Tau Ba and Bb are rotating much faster than V807 Tau A .
The uncertainty in the stellar effective temperatures and distance to the system currently limit the comparison of our dynamical mass measurements with predictions based on evolutionary tracks for pre-main sequence stars .
We also report preliminary results from a program to map the 3.6 cm radio emission from V807 Tau using the Very Long Baseline Array .
With continued monitoring , these observations will provide a precise parallax for placing the dynamical masses on an absolute scale .