The column density structure of Orion A depicted by N-PDF

作     者：Yue-Hui Ma Hong-Chi Wang Chong Li Ji Yang Yue-Hui Ma;Hong-Chi Wang;Chong Li;Ji Yang

作者机构：Purple Mountain Observatory and Key Laboratory of Radio AstronomyChinese Academy of SciencesNanjing 210033China University of Chinese Academy of SciencesBeijing 100049China School of Astronomy and Space ScienceUniversity of Science and Technology of ChinaAnhui 230026China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2020年第20卷第4期

页      面：139-155页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0704[理学-天文学] 0825[工学-航空宇航科学与技术] 

基　　金：supported by National Key R&D Program of China(2017YFA0402701) Key Research Program of Frontier Sciences of CAS(QYZDJSSW-SLH047) supports by the National Natural Science Foundation of China(Grant Nos.11503086 and 11503087) 

主　　题：ISM:clouds ISM:individual objects(Orion A) ISM:structure stars:formation surveys turbulence 

摘      要：We have conducted a large-field simultaneous survey of 12 CO,13 CO and C18O J=1-0 emission toward the Orion A giant molecular cloud(GMC)with a sky coverage of4.4 deg2 using the Purple Mountain Observatory(PMO)-13.7 m millimeter-wavelength *** use the probability distribution function of the column density(N-PDF)to investigate the distribution of molecular hydrogen in the Orion A *** H2 column density,derived from the 13CO emission,of the GMC is dominated by a log-normal distribution in the range from4×1021 to1.5×1023 cm-2 with excesses both at the low-density and high-density *** excess of the low-density end is possibly caused by an extended and low-temperature(10 K)component with velocities in the range of 5-8 km *** with the northern sub-regions,the southern sub-regions of the Orion A GMC contain less gas with column density in NH21.25×1022 *** dispersions of the N-PDFs of the sub-regions are found to correlate with the evolutionary stages of the clouds across the Orion A *** structure hierarchy of Orion A GMC is explored with the DENDROGRAM algorithm,and it is found that the GMC is composed of two *** structures except one in the tree have virial parameters less than 2,indicating self-gravity is important on the spatial scales from0.3 to4 *** power-laws and departures from lognormal distributions are found at the high-density end of N-PDFs for active star-forming regions,the N-PDFs of structures in the Orion A GMC are predominantly lognormal on scales from R0.4 to 4 pc.