On the Scarcity of Dense Cores (n > 105 cm‑3) in High-latitude Planck Galactic Cold Clumps
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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2024
- DOI:
- arXiv:
- arXiv:2401.14658
- Bibcode:
- 2024ApJ...963L...9X
- Keywords:
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- Star formation;
- Molecular clouds;
- High latitude field;
- 1569;
- 1072;
- 737;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 9 pages for the main text. 4 figures, 1 table. Published in Astrophysical Journal Letter