Radial velocities and V-band phot. of DI Tau

It has not been detected since, despite being targeted by five different studies that used a variety of methods and spanned more than 20yr. Here, we report the serendipitous rediscovery of DI Tau B during our Young Exoplanets Spectroscopic Survey (YESS).

Using radial velocity data from YESS spanning 17yr, new adaptive optics observations from Keck II, and a variety of other data from the literature, we derive a preliminary orbital solution for the system that effectively explains the detection and (almost all of the) non-detection history of DI Tau B. We estimate the dynamical masses of both components, finding that the large mass difference (q~0.17) and long orbital period (>~35yr) make the DI Tau system a noteworthy and valuable addition to studies of stellar evolution and pre-main-sequence models.