We present multi-epoch Very Long Baseline Array ( VLBA ) observations of V773 Tau A , the 51-day binary subsystem in the multiple young stellar system V773 Tau .
Combined with previous interferometric and radial velocity measurements , these new data enable us to improve the characterization of the physical orbit of the A subsystem .
In particular , we infer updated dynamical masses for the primary and the secondary components of 1.55 \pm 0.11 M _ { \odot } , and 1.293 \pm 0.068 M _ { \odot } , respectively , and an updated orbital parallax distance to the system of 135.7 \pm 3.2 pc , all consistent with previous estimates .
Using the improved orbit , we can calculate the absolute coordinates of the barycenter of V773 Tau A at each epoch of our VLBA observations , and fit for its trigonometric parallax and proper motion .
This provides a direct measurement of the distance to the system almost entirely independent of the orbit modeling .
The best fit yields a distance of 129.9 \pm 3.2 pc , in good agreement ( i.e .
within 1 \sigma ) with the distance estimate based on the orbital fit .
Taking the mean value of the orbital and trigonometric parallaxes , we conclude that V773 Tau is located at d = 132.8 \pm 2.3 pc .
The accuracy of this determination is nearly one order of magnitude better than that of previous estimates .
In projection , V773 Tau and two other young stars ( Hubble 4 and HDE 283572 ) recently observed with the VLBA are located toward the dark cloud Lynds 1495 , in the central region of Taurus .
These three stars appear to have similar trigonometric parallaxes , radial velocities , and proper motions , and we argue that the weighted mean and dispersion of their distances ( d = 131.4 pc and \sigma _ { d } = 2.4 pc ) provide a good estimate of the distance to and depth of Lynds 1495 and its associated stellar population .
The radio emission from the two sources in V773 Tau A is largely of gyrosynchrotron origin .
Interestingly , both sources are observed to become typically five times brighter near periastron than near apastron ( presumably because of increased flaring activity ) , and the separation between the radio sources near periastron appears to be systematically smaller than the separation between the stars .
While this clearly indicates some interaction between the individual magnetospheres , the exact mechanisms at play are unclear because even at periastron , the separation between the stars ( \sim 30 R _ { * } ) remain much larger than the radius of the magnetospheres around these low-mass young stars ( \sim 6 R _ { * } ) .