A molecular line study towards massive extended green object clumps in the southern sky: chemical properties

	A molecular line study towards massive extended green object clumps in the southern sky: chemical properties
	Yu, Naiping1,2 ; Wang, Jun-Jie1,2
刊名	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
	2015-08-11
卷号	451 期号:3 页码:2507-2516
关键词	stars: formation ISM: abundances ISM: clouds ISM: molecules
英文摘要	We present a molecular line study towards 31 extended green object (EGO) clumps in the southern sky using data from MALT90 (Millimetre Astronomy Legacy Team 90 GHz). According to previous multiwavelength observations, we divide our sample into two groups: massive young stellar objects (MYSOs) and HII regions. The most detected lines are N2H+ (J = 1 - 0), HCO+ (J = 1 - 0), HNC (J = 1 - 0), HCN (J = 1 - 0), HC3N (J = 10 - 9), (HCO+)-C-13 (J = 1 - 0), C2H (N = 1 - 0) and SiO (J = 2 - 1), indicating that most EGOs are indeed associated with dense clumps and recent outflow activities. The velocity widths of the N2H+ (J = 1 - 0), (HCO+)-C-13 (J = 1 - 0), C2H (N = 1 - 0) and HC3N (J = 10 - 9) lines are comparable to each other in MYSOs. However, in HII regions the velocity widths of the N2H+ (J = 1 - 0) and C2H (N = 1 - 0) lines tend to be narrower than those of (HCO+)-C-13 (J = 1 - 0) and HC3N (J = 10 - 9). Our results seem to support that N2H+ and C2H emissions mainly come from the gas inside quiescent clumps. In addition, we also find that the [N2H+]/[H13CO+] and [C2H]/[(HCO+)-C-13] relative abundance ratios decrease from MYSOs to H II regions. These results suggest depletion of N2H+ and C2H in the late stages of massive-star formation, probably caused by the formation of HII regions inside. N2H+ and C2H might be used as chemical clocks for massive-star formation by comparing with other molecules such as (HCO+)-C-13 and HC3N.
收录类别	SCI
语种	英语
WOS记录号	WOS:000360833700019
内容类型	期刊论文
源URL	[http://ir.bao.ac.cn/handle/114a11/5593]
专题	国家天文台_射电天文研究部
作者单位	1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China 2.NAOC TU Joint Ctr Astrophys, Lhasa 850000, Peoples R China
推荐引用方式 GB/T 7714	Yu, Naiping,Wang, Jun-Jie. A molecular line study towards massive extended green object clumps in the southern sky: chemical properties[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2015,451(3):2507-2516.
APA	Yu, Naiping,&Wang, Jun-Jie.(2015).A molecular line study towards massive extended green object clumps in the southern sky: chemical properties.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,451(3),2507-2516.
MLA	Yu, Naiping,et al."A molecular line study towards massive extended green object clumps in the southern sky: chemical properties".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 451.3(2015):2507-2516.