We present Herschel Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA . , ALMA Compact Array ( ACA ) , and Caltech Submillimeter Observatory ( CSO ) 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 seen in the interstellar medium .
The change in the NH _ { 2 } D 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 _ { 2 } D ^ { + } and ND _ { 3 } emission is detected with the ACA , extending S/SW from the peak of the single-dish NH _ { 2 } D emission .
The ACA data also reveal the presence a compact dust continuum source , with a mean size of \sim 1100 au , a central density of ( 1 - 2 ) \times 10 ^ { 7 } cm ^ { -3 } , and a mass of 0.2–0.4 M _ { \odot } .
The dust emission peak is displaced \sim 5 ^ { \prime \prime } to the south with respect to the N _ { 2 } D ^ { + } 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 .