MILLIMETER-WAVELENGTH APERTURE SYNTHESIS OBSERVATIONS OF MASSIVE STAR-FORMING REGIONS IN SAGITTARIUS-B2

We have observed the 1.3 mm continuum and the HC3N J = 25 --> 24 emission toward two massive star-forming regions in the core of the Sgr B2 molecular cloud, Sgr B2(N) and (M), using the three-element millimeter-wave interferometer of the Owens Valley Radio Observatory and the 10.4 m telescope of the Cal-tech Submillimeter Observatory. The interferometric continuum data reveal the presence of compact dust sources in each of the two fields observed. The northern continuum source is only resolved in the N-S direction (deconvolved FWHM size approximately 5'' or 0.2 pc). The HC3N J = 25 --> 24 interferometric data resolve a very energetic bipolar outflow (approximately 80 km s-1 full line width) associated with the northern source. The direction of the outflow is approximately perpendicular to the elongation of the continuum source. Thus the dust continuum emission may be tracing an inclined dense ridge which helps to collimate the large-scale outflow. The linear velocity gradient in the HC3N line core (approximately 55-75 km s-1) indicates that the ridge rotates at an angular velocity of approximately 50 km s-1 pc-1. The center of the molecular outflow associated with the northern source is coincident within the observational uncertainties with the center of the H2O maser emission and dust continuum emission. The HC3N velocity field is also similar to that indicated by H2O maser motions. In the northern source most of the single-dish HC3N flux density in a 30'' beam is detected in our interferometric map. The HC3N emission from the middle source is much more spatially extended and at all velocities a significant fraction of the single-dish flux density is resolved out in the interferometric map. However, the interferometric HC3N data reveal a bright, marginally resolved compact component (deconvolved FWHM size approximately 3''). Toward this component a SE-NW velocity gradient is observed. The resolution of our data prevents us from determining if the velocity gradient is due to outflow, rotation, or a combination of both.