Infall and outflow of molecular gas in Sgr B2

	Infall and outflow of molecular gas in Sgr B2
	Qin, Sheng-Li 1,2; Zhao, Jun-Hui 1; Moran, James M.1; Marrone, Daniel P.1; Patel, Nimesh A.1; Wang, Jun-Jie2 ; Liu, Sheng-Yuan 3; Kuan, Yi-Jehng 3,4
刊名	ASTROPHYSICAL JOURNAL
	2008-04-10
卷号	677 期号:1 页码:353-372
关键词	Galaxy : center ISM : individual (Sgr B2) ISM : kinematics and dynamics ISM : molecules radio lines : ISM stars : formation
英文摘要	Observations of two H2CO (3(03)-2(02) and 3(21)-2(20)) lines and continuum emission at 1.3 mm toward Sgr B2(N) and Sgr B2(M) have been carried out with the SMA. The mosaic maps of Sgr B2(N) and Sgr B2(M) in both continuum and lines show a complex distribution of dust and molecular gas in both clumps and filaments surrounding the compact star formation cores. We have observed a decelerating outflow originated from the Sgr B2(M) core, showing that both the redshifted and blueshifted outflow components have a common terminal velocity. This terminal velocity is 58 +/- 2 km s(-1). It provides an excellent method for determination of the systematic velocity of the molecular cloud. The SMA observations have also shown that a large fraction of absorption against the two continuum cores is redshifted with respect to the systematic velocities of Sgr B2(N) and Sgr B2(M), respectively, suggesting that the majority of the dense molecular gas is flowing into the two major cores where massive stars have been formed. We have solved the radiative transfer in a multilevel system with LVG approximation. The observed H2CO line intensities and their ratios can be adequately fitted with this model for the most of the gas components. However, the line intensities between the higher energy level transition H2CO(3(21)-2(20)) and the lower energy level transition H2CO(3(03)-2(02)) is reversed in the redshifted outflow region of Sgr B2(M), suggesting the presence of inversion in population between the ground levels in the two K ladders (K-1 = 10 and 2). The possibility of weak maser processes for the H2CO emission in Sgr B2(M) is discussed.
收录类别	SCI
语种	英语
WOS记录号	WOS:000254754300027
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/7497]
专题	国家天文台_射电天文研究部
作者单位	1.Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA 2.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 3.Acad Sinica Inst Astron & Astrophys, Taipei 106, Taiwan 4.Natl Taiwan Normal Univ, Dept Earth Sci, Taipei 116, Taiwan
推荐引用方式 GB/T 7714	Qin, Sheng-Li,Zhao, Jun-Hui,Moran, James M.,et al. Infall and outflow of molecular gas in Sgr B2[J]. ASTROPHYSICAL JOURNAL,2008,677(1):353-372.
APA	Qin, Sheng-Li.,Zhao, Jun-Hui.,Moran, James M..,Marrone, Daniel P..,Patel, Nimesh A..,...&Kuan, Yi-Jehng.(2008).Infall and outflow of molecular gas in Sgr B2.ASTROPHYSICAL JOURNAL,677(1),353-372.
MLA	Qin, Sheng-Li,et al."Infall and outflow of molecular gas in Sgr B2".ASTROPHYSICAL JOURNAL 677.1(2008):353-372.