Low-Mass Star-Forming Cores in the GF9 Filament

Abstract

We carried out an unbiased mapping survey of dense molecular cloud cores traced by the NH3 (1,1) and (2,2) inversion lines in the GF 9 filament, which contains an extremely young low-mass protostar, GF 9-2 (2006, ApJ, 653, 1369). The survey was conducted using the Nobeyama 45m telescope over a region of ~1.5° × 1° with an angular resolution of 73". The large-scale map revealed that the filament contains at least 7 dense cores, as well as 3 possible ones, located at regular intervals of ~0.9 pc. Our analysis shows that these cores have kinetic temperatures of ≾10K and LTE-masses of 1.8–8.2M☉, which makes them typical sites of low-mass star formation. All of the identified cores are likely to be gravitationally unstable, because their LTE-masses are larger than their virial masses. Since the LTE-masses and separations of the cores are consistent with the Jeans masses and lengths, respectively, for the low-density ambient gas, we argue that the identified cores formed via the gravitational fragmentation of the natal filamentary cloud.