Compact outflows associated with TMC-1 and TMC-1A

High spatial resolution observations are presented of the compact outflows associated with the young protostars TMC-1 (IRAS 04381 + 2540) and TMC-1A (IRAS 04365 + 2535) in Taurus. Emission in CO(1 - 0) imaged with the Owens Valley Millimeter Array shows the outflow lobes to be conical close to the star. Analysis of the outflow dynamics indicates that these objects are low-luminosity versions of the energetic outflows more commonly observed. Near-infrared images at H and K bands show a close correspondence between reflection nebulosity and the location of high-velocity gas and suggest the outflow cavity is evacuated, as do position-velocity diagrams of the CO(2 - 1). Comparison of the J = 1 - 0 transition with emission in the 2 - 1 line indicates that the excitation temperature in the high-velocity gas is higher than the surrounding Taurus cloud. We place limits on the inclination of both objects by comparing the data with theoretical outflow models and conclude that i similar to 40 degrees - 70 degrees for both objects. The deprojected opening angles of the outflow cones are then in the range 30 degrees - 40 degrees. None of the current outflow models satisfactorily explains the results for TMC-1 and TMC-1A, which are among the youngest class I sources in Taurus. We find their outflow structure shares many similarities with the more obscured and possibly younger class 0 objects, B335 and L1448-C. The main difference is the lower mechanical luminosities of the TMC-1 and TMC-1A outflows, reflecting a factor of 3 - 4 smaller linear extent and velocity and a factor of 10 - 20 lower mass than the L1448-C molecular jet source. Taken together, the four protostars share the common properties of (1) conical outflow lobes close to the star, (2) evacuated outflow cavities, and (3) relatively wide 30 degrees - 45 degrees opening angles. A successful theory of young stellar outflows must be able to explain these characteristics.