Planck Cold Clumps in the λ Orionis Complex. I. Discovery of an Extremely Young Class 0 Protostellar Object and a Proto-brown Dwarf Candidate in the Bright-rimmed Clump PGCC G192.32-11.88
Sanhueza, Patricio; Kwon, Woojin; Lai, Shih-Ping; Choi, Minho; Fuller, Gary; Kang, Miju; Kim, Mi-Ryang; Kim, Kee-Tae; Lee, Chang Won; Lee, Jeong-Eun; Li, Di; Liu, Tie; Tang, Ya-Wen; Yuan, Jinghua; Yi, Hee-Weon; Zhang, Qizhou; Wang, Ke; Liu, Hauyu Baobab; Qin, Sheng-Li; Wu, Yuefang; Mardones, Diego; Tatematsu, Ken'ichi; Hirota, Tomoya; Chen, Huei-Ru; Xu, Ye; Yang, Ji; Zhang, Huawei; Juvela, Mika; Goldsmith, Paul F.; Thompson, Mark; Henkel, Christian; Ristorcelli, Isabelle; Liu, Sheng-yuan; Naomi, Hirano; Koch, Patrick; He, JinHua; Rivera-Ingraham, Alana; Cunningham, Maria R.; Nguyen Luong, Quang; Meng, FanYi
South Korea, United States, China, Japan, Finland, United Kingdom, Taiwan, Germany, Saudi Arabia, Spain, Australia, France, Chile
Abstract
We are performing a series of observations with ground-based telescopes toward Planck Galactic cold clumps (PGCCs) in the λ Orionis complex in order to systematically investigate the effects of stellar feedback. In the particular case of PGCC G192.32-11.88, we discovered an extremely young Class 0 protostellar object (G192N) and a proto-brown dwarf candidate (G192S). G192N and G192S are located in a gravitationally bound bright-rimmed clump. The velocity and temperature gradients seen in line emission of CO isotopologues indicate that PGCC G192.32-11.88 is externally heated and compressed. G192N probably has the lowest bolometric luminosity (∼0.8 {L}⊙ ) and accretion rate (6.3 × 10-7 {M}⊙ yr-1) when compared with other young Class 0 sources (e.g., PACS Bright Red Sources) in the Orion complex. It has slightly larger internal luminosity (0.21 ± 0.01 {L}⊙ ) and outflow velocity (∼14 km s-1) than the predictions of first hydrostatic cores (FHSCs). G192N might be among the youngest Class 0 sources, which are slightly more evolved than an FHSC. Considering its low internal luminosity (0.08 ± 0.01 {L}⊙ ) and accretion rate (2.8 × 10-8 {M}⊙ yr-1), G192S is an ideal proto-brown dwarf candidate. The star formation efficiency (∼0.3%-0.4%) and core formation efficiency (∼1%) in PGCC G192.32-11.88 are significantly smaller than in other giant molecular clouds or filaments, indicating that the star formation therein is greatly suppressed owing to stellar feedback.