Planck Galactic Cold Clumps in Two Regions: The First Quadrant and the Anticenter Direction Region

Abstract

Abstract Sixty-five Planck Galactic cold clumps (PGCCs) from the first quadrant (IQuad) and 39 from the anticenter direction region (ACent) were observed in 12CO, 13CO, and C18O J = 1–0 lines using the 13.7 m telescope of the Purple Mountain Observatory. All the targets were detected in all three lines, except for 12 IQuad and 8 ACent PGCCs without C18O detection. Seventy-six and 49 velocity components were obtained in IQuad and ACent respectively; 146 cores were extracted from 76 IQuad clumps and 100 cores from 49 ACent clumps. The average T ex of IQuad cores and ACent cores is 12.4 K and 12.1 K, respectively. The average line widths of 13CO of IQuad cores and ACent cores are 1.55 km s−1 and 1.77 km s−1, respectively. Among the detected cores, 24 in IQuad and 13 in ACent have asymmetric line profiles. The small blue excesses, ∼0.03 in IQuad and 0.01 in ACent, indicate that star formation is not active in these PGCC cores. Power-law fittings of the core mass function to the high-mass end give indices of −0.57 in IQuad and −1.02 in ACent, which are flatter than the slope of the initial mass function given by Salpeter. The large turnover masses of 28 for IQuad cores and 77 for ACent cores suggest low star formation efficiencies in PGCCs. The correlation between virial mass and gas mass indicates that most PGCC cores in both regions are not likely pressure-confined.