S187-SCP-1 (H2) - A CURVED MOLECULAR-HYDROGEN OUTFLOW

We imaged in the near-infrared the region associated with IRAS 01202+6 133, which lies to the southeast of the Sharpless H II region S187, de signated as S187 IR. We report the discovery of a curved molecular hyd rogen outflow that extends over a region of 76 '' (0.38 pc at D = 1 kp c), identified as S187:SCP 1 (H2). The outflow changes direction by mo re than 90 degrees in a continuous way and is the most dramatic exampl e of direction variability in a jet source known to date. The outflow- driving source is probably an extreme T Tauri star identified as NIRS I located at the apex of the curved structure. The curved jetlike stru cture shows a sinuous chain of several emission knots located along an extended H-2 nebulosity. The similarity with the properties of optica l Herbig-Haro jets observed in the near-IR allows us to conclude that S187:SCP I (H2) is a Herbig-Haro object. We discuss whether the supers onic side-wind model proposed by Canto & Raga provides the best physic al scenario for the curved outflow seen in S187 IR. According to this model, the initial angle of the jet is nearly opposite to the wind dir ection, and the wind action turns the jet through 150 degrees, resulti ng in a minimum radius of curvature of 0.14 pc. Assuming typical value s for T Tauri stars in molecular environments ((M) over dot = 10(-7) M . yr(-1), v(jet)= 150 km s(-1), v(sound) = s = 10 km s(-1), n(a) = 10( 4) cm(-3)), the required wind velocity is 10 km s(-1), which is of the same order of magnitude as the typical velocities of T Tauri stars re lative to their surrounding molecular clouds. Furthermore, the predict ed position of the stagnation point, where the hydrostatic pressure in the jet equals the ram pressure of the wind, coincides with an observ ed H-2 emission maximum along the curved part of the outflow. The pred icted curve extends to a bow-shock-like H-2 nebulosity located 2' (0.4 6 pc at D = 1 kpc) away from the curved outflow.