On the Scarcity of Dense Cores (n > 105 cm‑3) in High-latitude Planck Galactic Cold Clumps
Sanhueza, Patricio; Ward-Thompson, Derek; Whitworth, Anthony; Kwon, Woojin; Soam, Archana; Lai, Shih-Ping; Chen, Huei-Ru Vivien; Doi, Yasuo; Gu, Qilao; Johnstone, Doug; Lee, Chang Won; Liu, Tie; Liu, Sheng-Yuan; Zhang, Chuan-Peng; Zhou, Jianjun; Zhu, Lei; Eden, David; Wang, Ke; Garay, Guido; Wu, Yuefang; Mardones, Diego; Tatematsu, Ken'ichi; Ren, Zhiyuan; Traficante, Alessio; White, Glenn J.; Xu, Fengwei; Tóth, L. Viktor; Juvela, Mika; Rawlings, Mark G.; Alina, Dana; Falgarone, Edith; Hirano, Naomi; He, Jinhua; Ristorcelli, Isabelle; Liu, Xunchuan; Goldsmith, Paul; Chakali, Eswaraiah
China, United Kingdom, Finland, Chile, Canada, United States, India, Italy, France, Taiwan, Japan, South Korea, Kazakhstan, Hungary
Abstract
High-latitude (∣b∣ > 30°) molecular clouds have virial parameters that exceed 1, but whether these clouds can form stars has not been studied systematically. Using JCMT SCUBA-2 archival data, we surveyed 70 fields that target high-latitude Planck Galactic cold clumps (HLPCs) to find dense cores with density of 105–106 cm‑3 and size of <0.1 pc. The sample benefits from both the representativeness of the parent sample and its coverage of the densest clumps at the high column density end (>1 × 1021 cm‑2). At an average rms of 15 mJy beam‑1, we detected Galactic dense cores in only one field, G6.04+36.77 (L183) while also identifying 12 extragalactic objects and two young stellar objects. Compared to the low-latitude clumps, dense cores are scarce in HLPCs. With synthetic observations, the densities of cores are constrained to be n c ≲ 105 cm‑3 should they exist in HLPCs. Low-latitude clumps, Taurus clumps, and HLPCs form a sequence where a higher virial parameter corresponds to a lower dense-core detection rate. If HLPCs were affected by the Local Bubble, the scarcity should favor turbulence-inhibited rather than supernova-driven star formation. Studies of the formation mechanism of the L183 molecular cloud are warranted.