2016ApJ...827..133L

We present Herschel,^11 ALMA Compact Array (ACA), and Caltech Submillimeter Observatory observations of the prestellar core in L1689N, which has been suggested to be interacting with a molecular outflow driven by the nearby solar-type protostar IRAS 16293-2422. This source is characterized by some of the highest deuteration levels observed in the interstellar medium. The change in the NH_2D line velocity and width across the core provides clear evidence of an interaction with the outflow, traced by the high-velocity water emission. Quiescent, cold gas characterized by narrow line widths is seen in the NE part of the core, while broader, more disturbed line profiles are seen in the W/SW part. Strong N_2D^+ and ND_3 emission is detected with ACA extending S/SW from the peak of the single-dish NH_2D emission. The ACA data also reveal the presence a compact dust continuum source with a mean size of ∼1100 au, a central density of (1-2) x 10^7 cm^-3, and a mass of 0.2-0.4 M_☉. The dust emission peak is displaced ∼5'' to the south with respect to the N_2D^+ and ND_3 emission, as well as the single-dish dust continuum peak, suggesting that the northern, quiescent part of the core is characterized by spatially extended continuum emission, which is resolved out by the interferometer. We see no clear evidence of fragmentation in this quiescent part of the core, which could lead to a second generation of star formation, although a weak dust continuum source is detected in this region in the ACA data.