Very Large Array Observations of Proper Motions in YLW 15

Using high angular resolution (~0 3) Very Large Array (VLA) observations made at 3.6 cm during the period from 1990 to 2002, we report the detection of proper motions in the components of the binary source YLW 15. The absolute proper motions observed in these two protostars, of the order of 26 mas yr -1 , or ~15 km s -1 at a distance of 120 pc, are very similar in magnitude and direction to those of another protostar and of T Tauri stars in the same region and are attributed to the large-scale motions of the parent molecular complex. The relative astrometry between the two components (separated by ~0 6) reveals orbital proper motions that suggest that a lower limit to the total mass and an upper limit to the period of the binary system are ~1.7 M ☉ and 360 yr, respectively. The results also suggest that VLA 1 is more massive than VLA 2.