  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 GF9 filament which
contains an extremely young low-mass protostar GF9-2 (Furuya et al. 2006, ApJ,
653, 1369). The survey was conducted using the Nobeyama 45m telescope over a
region of ~1.5 deg 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 $\lesssim$ 10 K and LTE-masses of 1.8
-- 8.2 Msun, making them typical sites of low-mass star formation. All 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 have formed via the gravitational fragmentation of the natal filamentary
cloud.
