2011ApJ...732..101I

We present the results of C¹⁸O(J = 1-0) mapping observations of a 20'x18' area in the Lynds 1204 molecular cloud associated with the Sharpless 2-140 (S140) H II region. The C¹⁸O cube (α-δ-v_LSR) data show that there are three clumps of sizes ∼1 pc in the region. Two of these have peculiar redshifted velocity components at their edges, which can be interpreted as the results of the interaction between the cloud and the Cepheus Bubble. From the C¹⁸O cube data, clumpfind identified 123 C¹⁸O cores, which have mean radius, velocity width in FWHM, and LTE mass of 0.36±0.07 pc, 0.37±0.09 km/s, and 41±29 M_☉, respectively. Considering the uncertainty in the C¹⁸O abundance, all the cores in S140 are most likely to be gravitationally bound. We derived a C¹⁸O core mass function (CMF), which shows a power-law-like behavior above a turnover at 30 M_☉. The best-fit power-law index of -2.1±0.2 is quite consistent with that of the initial mass function (IMF) and the C¹⁸O CMF in the OMC-1 region as found by Ikeda & Kitamura. Kramer et al. estimated the power-law index of -1.65 in S140 from the C¹⁸O(J = 2-1) data, which is inconsistent with this study. The C¹⁸O(J = 2-1) data are spatially limited to the central part of the cloud and are likely to be biased toward high-mass cores, leading to the flatter CMF. Consequently, this study and our previous study strongly support that the power-law form of the IMF has already been determined at the density of ≲ 10³-10⁴/cm3, traced by the C¹⁸O(J = 1-0) line.