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银河系大红外尘泡N24周围的分子云环境与恒星形成
Alternative TitleMolecular environs and triggered star formation around the large Galactic infrared bubble N24
李旭
Subtype硕士
Thesis Advisor加尔肯·叶生别克
2019
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name理学硕士
Degree Discipline天体物理
Keyword大质量恒星形成,星际介质,电离氢区,红外尘泡,分子云,外向流 Massive star formation,interstellar medium,H II region,infrared bubble, molecular cloud,outflow
Abstract银河系中普遍存在着来自大质量恒星的反馈活动,这些反馈活动伴随着大质量恒星的形成与演化过程而产生,并通过不同种方式作用于星际介质上。小尺度而言,它可以决定恒星形成的最终质量。大尺度上,它可以影响其所在的分子云环境,进而触发或抑制周围恒星的形成。作为反馈活动的典例,电离氢区的膨胀对银河系内恒星的形成有着深刻影响。 本文主要围绕银河系大红外尘泡N24周围的分子云环境与恒星形成而展开,利用公开的2MASS、Spifzer、Herschel、ATLASGAL及MAGPIS等由近红外到射电波段的数据对尘泡N24周围的尘埃分布及物理特性开展了多波段研究。使用Clupfind2d算法,我们在尘泡壳层上证认了23个致密团块,其大小和质量分别在0.65-1.73pc和600-16300M。范围内。同时,我们利用南山26米射电望远镜对NH2(1,1)和(2,2)进行了观测,并结合GRS13CO(1-0)数据,研究了尘泡N24上的分子云环境及其物理特性。通过对这23个致密团块的动力学温度与引力稳定性的研究,表明它们其中的几个处于引力坍缩状态,而这些团块的质量-半径分布以及团块上YSOs的SED拟合结果则进一步表明N24的壳层是一个正在形成大质量恒星的区域。作为大质量星的反馈影响,我们在大质量年轻星Y3所在的HII区,利用GRS18CO(1-0)的线翼,发现了一个明显的外向流的存在。最后,我们对比了尘泡N24的动力学年龄以及分子云碎片化的时间尺度,并结合壳层上高丰度的YSOs与致密团块,认为“扫集-坍缩”模型是尘泡N24膨胀触发恒星形成的主要机制。然而,在尘泡的边缘,一些RDC及亮边云的存在,则进一步表明“辐射内爆”模型在N24壳层上也扮演了极为重要的角色。
Other AbstractThe feedback activity of massive stars is widespread in the Milky Way galaxy, these are associated with the fomation and evolution of massive stars and interact with the interstellar medium in different ways. They may set the final masses on a small scale and affect the structures of their parent molecular cloud environments on a large scale, triggering or quenching star formation. As a classic example of feedback activity, the expansion of H II region has a profound effect on star formation in the Milky Way galaxy. In this paper,a multi-wavelength analysis of the large Galactic infrared bubble N 24 is has presented in order to investigate the molecular and star formation environment around expanding H II regions. Using archival data from 2MASS, Spitzer, Herschel, ATLASGAL, and MAGPIS, the distribution and physical properties of the dust over the entire bubble are studied. Twenty three dense clumps are identified using the Clumpfind2d algorithm with sizes and masses in the range 0.65-1.73 pe and 600-16300M, respectively. To analyse the molecular environment in N 24, observations of NHa(1,1) and (2,2) were carried out using the Nanshan 26-m radio telescope. Analysis of the kinetic temperature and gravitational stability of these clumps suggests gravitational collapse in several of them. The mass-size distributions of the clumps andthe presence of massive young protostars indicate that the shell of N 24 is a region of ongoing massive star formation. To study the feedback effects of massive stars, we surprisingly find an apparent outflow in the line wing of the GRS 18CO(1-0) in the HII region where Y3 is located. The estimated dynamical and fragmentation time-scales as well as an overabundance of YSOs and clumps on the periphery suggest the possibilityof the"collect and collapse"mechanism in play at the bubble border, but the existence of the IRDC at the edge of bubble indicates that '"radiation-driven implosion"may work there.
Pages66
Language中文
Document Type学位论文
Identifierhttp://ir.xao.ac.cn/handle/45760611-7/2715
Collection研究生学位论文
Affiliation中国科学院新疆天文台
First Author AffilicationXinjiang Astronomical Observatory, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
李旭. 银河系大红外尘泡N24周围的分子云环境与恒星形成[D]. 北京. 中国科学院大学,2019.
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