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Planck Cold Clumps in the lambda Orionis Complex. II. Environmental Effects on Core Formation

Yi, H-W, Lee, J-E, Liu, T, Kim, K-T, Choi, M, Eden, DJ, Evans, NJ, Di Francesco, J, Fuller, G, Hirano, N, Juvela, M, Kang, S-J, Kim, G, Koch, PM, Lee, CW, Li, D, Liu, H-YB, Liu, H-L, Liu, S-Y, Rawlings, MG , Ristorcelli, I, Sanhueza, P, Soam, A, Tatematsu, K, Thompson, M, Toth, L, Wang, K, White, GJ, Wu, Y and Yang, Y-L (2018) Planck Cold Clumps in the lambda Orionis Complex. II. Environmental Effects on Core Formation. Astrophysical Journal Supplement Series, 236 (2). ISSN 0067-0049

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Abstract

Based on the 850 μm dust continuum data from SCUBA-2 at James Clerk Maxwell Telescope (JCMT), we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the λ Orionis cloud to those of PGCCs in the Orion A and B clouds. The Orion A and B clouds are well-known active star-forming regions, while the λ Orionis cloud has a different environment as a consequence of the interaction with a prominent OB association and a giant H II region. PGCCs in the λ Orionis cloud have higher dust temperatures (T d = 16.13 ± 0.15 K) and lower values of dust emissivity spectral index (β = 1.65 ± 0.02) than PGCCs in the Orion A (T d = 13.79 ± 0.21 K, β = 2.07 ± 0.03) and Orion B (T d = 13.82 ± 0.19 K, β = 1.96 ± 0.02) clouds. We find 119 substructures within the 40 detected PGCCs and identify them as cores. Out of a total of 119 cores, 15 cores are discovered in the λ Orionis cloud, while 74 and 30 cores are found in the Orion A and B clouds, respectively. The cores in the λ Orionis cloud show much lower mean values of size R = 0.08 pc, column density N(H2) = (9.5 ± 1.2) × 1022 cm−2, number density n(H2) = (2.9 ± 0.4) × 105 cm−3, and mass M core = 1.0 ± 0.3 M ⊙ compared to the cores in the Orion A [R = 0.11 pc, N(H2) = (2.3 ± 0.3) × 1023 cm−2, n(H2) = (3.8 ± 0.5) × 105 cm−3, and M core = 2.4 ± 0.3 M ⊙] and Orion B [R = 0.16 pc, N(H2) = (3.8 ± 0.4) × 1023 cm−2, n(H2) = (15.6 ± 1.8) × 105 cm−3, and M core = 2.7 ± 0.3 M ⊙] clouds. These core properties in the λ Orionis cloud can be attributed to the photodissociation and external heating by the nearby H II region, which may prevent the PGCCs from forming gravitationally bound structures and eventually disperse them. These results support the idea of negative stellar feedback on core formation.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0306 Physical Chemistry (incl. Structural)
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: IOP Publishing
Related URLs:
Date Deposited: 09 Oct 2019 09:31
Last Modified: 09 Oct 2019 09:45
DOI or Identification number: 10.3847/1538-4365/aac2e0
URI: http://researchonline.ljmu.ac.uk/id/eprint/11504

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