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	Perturbation analysis of a general polytropic homologously collapsing stellar core
	Cao, Yi ; Lou, Yu-Qing
	2010-10-12 ; 2010-10-12
关键词	hydrodynamics instabilities waves stars: neutron stars: oscillations supernovae: general SELF-SIMILAR DYNAMICS SHOCK SUPERNOVA MECHANISM MASSIVE STARS NEUTRON-STAR GRAVITATIONAL COLLAPSE SCHWARZSCHILDS CRITERION BACKGROUND POLYTROPES ENVELOPE EXPANSION GASEOUS SPHERES RADIO PULSARS Astronomy & Astrophysics
中文摘要	For dynamic background models of Goldreich & Weber and Lou & Cao, we examine three-dimensional perturbation properties of oscillations and instabilities in a general polytropic homologously collapsing stellar core of a relativistically hot medium with a polytropic index gamma = 4/3. Perturbation behaviours, especially internal gravity g modes, depend on the variation of specific entropy in the collapsing core. Among possible perturbations, we identify acoustic p modes and surface f modes as well as internal gravity g(+) and g(-) modes. As in stellar oscillations of a static star, we define g(+) and g(-)modes by the sign of the Brunt-Vaisala buoyancy frequency squared N-2 for a collapsing stellar core. A new criterion for the onset of instabilities is established for a homologous stellar core collapse. We demonstrate that the global energy criterion of Chandrasekhar is insufficient to warrant the stability of general polytropic equilibria. We confirm the acoustic p-mode stability of Goldreich & Weber, even though their p-mode eigenvalues appear in systematic errors. Unstable modes include g(-) modes and sufficiently high-order g(+) modes, corresponding to core instabilities. Such instabilities occur before the stellar core bounce, in contrast to instabilities in other models of supernova (SN) explosions. The breakdown of spherical symmetry happens earlier than expected in numerical simulations so far. The formation and motion of the central compact object are speculated to be much affected by such g-mode instabilities. By estimates of typical parameters, unstable low-order l = 1 g(-) modes may produce initial kicks of the central compact object. Other high-order and high-degree unstable g modes may shred the nascent neutron core into pieces without an eventual compact remnant (e. g. SN 1987A). Formation of binary pulsars and planets around neutron stars might originate from unstable l = 2 g-modes and high-order high-degree g modes, respectively.
语种	英语 ; 英语
出版者	WILEY-BLACKWELL PUBLISHING, INC ; MALDEN ; COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/81517]
专题	清华大学
推荐引用方式 GB/T 7714	Cao, Yi,Lou, Yu-Qing. Perturbation analysis of a general polytropic homologously collapsing stellar core[J],2010, 2010.
APA	Cao, Yi,&Lou, Yu-Qing.(2010).Perturbation analysis of a general polytropic homologously collapsing stellar core..
MLA	Cao, Yi,et al."Perturbation analysis of a general polytropic homologously collapsing stellar core".(2010).

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