THE CIRCUMSTELLAR ENVELOPES AROUND 3 PROTOSTARS IN TAURUS

We have investigated the distribution of circumstellar material around three Class I protostars in Taurus. TMC1 (LRAS 04381+2540), TMC1A (IR AS 04365+2535) and Hare 6-10 (IRAS 04263+2426) have all been mapped in 790-mu m dust continuum emission using the James Clerk Maxwell Telesc ope, and TMC1A has also been imaged at lambda 1.1 mm. In addition, we present a (CO)-C-12 J = 2-1 map of Hare 6-10 obtained using the Caltec h Submillimeter Observatory. The dust emission from TMC1 is extended a nd is oriented perpendicular to its outflow, with little evidence for a compact disc component. The submillimetre emission from TMC1A is cen trally peaked, with a weak extension in the direction of the outflow a t both 790 mu m and 1.1 mm. It is possible that the interaction of the outflow with the surrounding cloud is heating the dust. The emission from Hare 6-10 is oriented roughly perpendicular to the direction of s everal Herbig-Haro objects in the region. There is no clear bipolar mo lecular outflow structure in the CO(2-1) map, and the relatively low v elocities observed in the line wings suggest that any such system must lie close to the plane of the sky. If the dust emission from the enve lopes is optically thin and a temperature distribution can be specifie d, the broad-band spectral energy distribution (SED) can be used to co nstrain the density profile. We isolate the envelope SEDs for our sour ces by subtracting possible disc and wind components from the submilli metre flux densities, and use a simple model to derive the radial powe r-law dependence of the density in each case. We find that for a densi ty distribution rho proportional to r(-p) the values of p are 0.93 +/- 0.25, 0.81 +/- 0.30 and 1.22 +/- 0.11 for TMC1, TMC1A and Hare 6-10 r espectively, which for all but Hare 6-10 are considerably shallower th an can currently be explained by collapse theory. We suggest that the envelopes around TMC1 and TMC1A may be rotationally supported, but tha t the Hare 6-10 envelope may still be infalling. The envelope masses a re similar to 0.02-0.03 M. in all cases.