QQ客服 官方微博 反馈留言

	Self-similar polytropic champagne flows in H II regions
	Hu, Ren-Yu ; Lou, Yu-Qing
	2010-05-06 ; 2010-05-06
关键词	hydrodynamics shock waves stars: formation stars: winds, outflows ISM: clouds H II regions GRAVITATING GASEOUS SPHERES COMPACT HII-REGIONS STAR-FORMATION GAS-DYNAMICS ISOTHERMAL SPHERES COLLAPSE HYDRODYNAMICS EVOLUTION EXPANSION CLUSTERS Astronomy & Astrophysics
中文摘要	We explore large-scale hydrodynamics of H II regions for various self-similar shock flows of a polytropic gas cloud under self-gravity and with quasi-spherical symmetry. We formulate cloud dynamics by invoking specific entropy conservation along streamlines and obtain global self-similar 'champagne flows' for a conventional polytropic gas with shocks as a subclass. Molecular cloud cores are ionized and heated to high temperatures after the onset of nuclear burning of a central protostar. We model subsequent evolutionary processes in several ways and construct possible self-similar shock flow solutions. We may neglect the mass and gravity of the central protostar. The ionization and heating of the surrounding medium drive outflows in the inner cloud core and a shock travels outwards, leading to the so-called 'champagne phase' with an expanding outer cloud envelope. Complementarily, we also consider the expansion of a central cavity around the centre. As the inner cloud expands plausibly due to powerful stellar winds, a cavity (i.e. 'void' or 'bubble') can be created around the centre, and when the cavity becomes sufficiently large, one may neglect the gravity of the central protostar. We thus present self-similar shock solutions for 'champagne flows' with an expanding central void. We compare our solutions with isothermal solutions and find that the generalization to the polytropic regime brings about significant differences of the gas dynamics, especially for cases of n < 1, where n is a key scaling index in the self-similar transformation. We also compare our global polytropic self-similar solutions with numerical simulation son the expansion of H II regions. We further explore other possible dynamic evolutions of H II regions after the initiation of nuclear burning of the central protostar, for example asymptotic inflows or contractions far from the cloud centre and the ongoing infall around a central protostar. In particular, it is possible to use the downstream free-fall solution with shocks to describe the dynamic evolution of H II regions shortly after the nascence of the central protostar. We also give an analysis on the invariant form of self-similar polytropic flows by ignoring self-gravity.
语种	英语 ; 英语
出版者	BLACKWELL PUBLISHING ; OXFORD ; 9600 GARSINGTON RD, OXFORD OX4 2DQ, OXON, ENGLAND
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/14932]
专题	清华大学
推荐引用方式 GB/T 7714	Hu, Ren-Yu,Lou, Yu-Qing. Self-similar polytropic champagne flows in H II regions[J],2010, 2010.
APA	Hu, Ren-Yu,&Lou, Yu-Qing.(2010).Self-similar polytropic champagne flows in H II regions..
MLA	Hu, Ren-Yu,et al."Self-similar polytropic champagne flows in H II regions".(2010).

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。