2018ApJS..236...49Z

In order to understand the initial conditions and early evolution of star formation in a wide range of Galactic environments, we carried out an investigation of 64 Planck Galactic cold clumps (PGCCs) in the second quadrant of the Milky Way. Using the ¹³CO and C¹⁸O J = 1-0 lines and 850 µm continuum observations, we investigated cloud fragmentation and evolution associated with star formation. We extracted 468 clumps and 117 cores from the ¹³CO line and 850 µm continuum maps, respectively. We made use of the Bayesian distance calculator and derived the distances of all 64 PGCCs. We found that in general, the mass-size plane follows a relation of m ∼ r^1.67. At a given scale, the masses of our objects are around 1/10 of that of typical Galactic massive star-forming regions. Analysis of the clump and core masses, virial parameters, densities, and mass-size relation suggests that the PGCCs in our sample have a low core formation efficiency (∼3.0%), and most PGCCs are likely low-mass star-forming candidates. Statistical study indicates that the 850 µm cores are more turbulent, more optically thick, and denser than the ¹³CO clumps for star formation candidates, suggesting that the 850 µm cores are likely more appropriate future star formation candidates than the ¹³CO clumps.