THE MOLECULAR ENVIRONMENT OF THE HH-34 SYSTEM

We present single-dish (angular resolution similar to 40'') and VLA (a ngular resolution similar to 4'') ammonia observations toward the HH 3 4 region. Two main condensations are distinguished in both our single- dish and our VLA maps. The northern ammonia condensation is resolved b y the VLA as an arclike structure that surrounds the east side of the star HH 34 IRS (the exciting source of the jet) and coincides in proje ction with Re 24, the reflection nebula associated with the infrared s ource IRS 5. We suggest that this ammonia structure is tracing the wal l of a cavity around HH 34 IRS. Our results are in good agreement with the hypothesis that this cavity was created by the stellar wind from HH 34 IRS, indicating that along the life of the star two kinds of ste llar wind might have been present: a low-collimation wind that created the cavity, and a highly collimated wind that is at the origin of the jet. A second VLA ammonia condensation coincides with Re 23, the brig htest part of the are of optical nebulosity previously proposed to be tracing the western wall of a cavity that contains the jet. The inner edges of these two ammonia condensations coincide with zones of a high level of polarization of the optical emission. With the angular resol ution of our VLA observations, no ammonia (1, 1) emission is detected directly associated with the star HH 34 IRS, setting an upper limit of 0.1[X(NH3)/10(-8)](-1) M. for the mass of a possible circumstellar di sk. From our single-dish observations, we find that there is extended emission (similar to 3') of high-density gas, not seen with the VLA. F or this gas we estimate a total mass of similar to 15 M. and a kinetic temperature of 15 K.