Abstract:
We present the results of molecular line observations performed toward the NGC 2068 and NGC 2071 regions of
the Orion B cloud as the TRAO-FUNS project to study the roles of the filamentary structure in the formation of
dense cores and stars in the clouds. Gaussian decomposition for the C18O spectra with multiple velocity
components and the application of a friends-of-friends algorithm for the decomposed components allowed us to
identify a few tens of velocity-coherent filaments. We also identified 48 dense cores from the observations of N2H+
using a core finding tool, FellWalker. We performed a virial analysis for these filaments and dense cores, finding
that the filaments with N2H+ dense core are thermally supercritical, and the filaments with a larger ratio between
the line mass and the thermal critical line mass tend to have more dense cores. We investigated the contribution of
the nonthermal motions in dense cores and filaments, showing the dense cores are mostly in transonic/subsonic
motions while their natal filaments are mostly in supersonic motions. This may indicate that gas turbulent motions
in the filaments have been dissipated at the core scale to form the dense cores there. The filaments with
(dynamically evolved) dense cores in infalling motions or with NH2D bright (or chemically evolved) dense cores
are all found to be gravitationally critical. Therefore, the criticality of the filament is thought to provide a key
condition for its fragmentation, the formation of dense cores, and their kinematical and chemical evolution
