Small-scale structure of the circumstellar gas around the very young outflow-driving source L483-FIR.
FULLER G.A. and WOOTTEN A.
Abstract (from CDS):
A remarkable young stellar object in L483 numbers among the fewer than a dozen known youngest protostars, those with ``class 0'' spectral energy distributions. We report high angular and spectral resolution images of bright NH3(1,1) and NH3(2,2) line emission arising from the molecular gas near this object. Along the ridge of dense gas traced by the NH3 (1,1) emission there is a velocity gradient of ∼4 km.s–1.pc–1. We also report images of dust emission at λ450 µm and λ850 µm. The images correspond well over scales of thousands of AU. Near the star, however, the ammonia map corresponds in detail more closely with an image taken at λ3.4 µm than to the submillimeter images in that absorption in the near infrared corresponds to an emission deficit in the ammonia maps. In the region of the deficit, the ammonia (1,1) line displays high optical depths, and its velocity is blueshifted relative to nearby gas and to other molecular lines emanating from the region. We offer a specific model incorporating infall from the surrounding core onto the region within 3000 AU of the protostar.