Core formation in different environments: Planck Galactic Cold Clumps (PGCCs) in the λ Orionis cloud, Orion A and Orion B clouds

  • Yi, HeeWeon (School of Space Research, Kyung Hee University) ;
  • Lee, Jeong-Eun (School of Space Research, Kyung Hee University) ;
  • Liu, Tie (Korea Astronomy and Space Science Institute) ;
  • Kim, Kee-Tae (Korea Astronomy and Space Science Institute) ;
  • Wu, Yuefang (Department of Astronomy, Peking University)
  • Published : 2016.10.12

Abstract

Based on the $850{\mu}m$ dust continuum data from James Clerk Maxwell Telescope (JCMT)/SCUBA-2, we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the ${\lambda}$ Orionis cloud with PGCCs in other molecular clouds, Orion A and Orion B. The Orion A and Orion B clouds are well known active star-forming region, while, ${\lambda}$ Orionis cloud has a different environment associating with prominent OB associations and a giant H II region. PGCCs in the ${\lambda}$ Orionis cloud have higher dust temperatures (Td~16.08 K) and lower values of dust emissivity (${\beta}{\sim}1.65$) than Orion A and Orion B clouds. In addition, we found the lowest detection rate (16 %, 8 out of 50) of PGCCs at $850{\mu}m$ in the ${\lambda}$ Orionis cloud while among three regions; Orion A and Orion B clouds show much higher detection rates of ~ 76 % (23 out of 30) and 56 % (9 out of 16), respectively. The detected 8 PGCCs in the ${\lambda}$ Orionis cloud have substructures and we identified 15 cores. The cores also show much lower median values of size (~0.08 pc), column density (~ ), number density (~ ), and mass (~ ) compared with other cores in the Orion A and Orion B clouds. These core properties in the ${\lambda}$ Orionis cloud can be attributed to the compression 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 well present the negative stellar feedback to core formation.

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