Observations of Herbig-Haro objects and their surrounding dark clouds

A survey was conducted toward 29 Herbig-Haro objects in the (J, K) = (1, 1) line of NH3, followed by mapping of the two strongest sources in the NGC 1333 region and the Serpens region. Herbig-Haro objects are found to be associated with dense (neutral H2 exceeding 5000/cu cm) neutral material, although these are not found to be the sites of on-going star formation. Cloud fragmentation appears to have occurred in the regions mapped. Rotation is present with velocity gradients of 1-2 km/s pc. Dynamics and stability against collapse are discussed for these regions. Formation of stars of different spectral types is also discussed. In the case of NGC 1333, NH3 results are used to constrain existing models of CO emission in the region.