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Titolo:
The crust of rotating strange quark stars

Autore:

Indirizzi:: Polish Acad Sci, N Copernicus Astron Ctr, PL-00716 Warsaw, Poland Polish Acad Sci Warsaw Poland PL-00716 tron Ctr, PL-00716 Warsaw, Poland Observ Paris, CNRS, UMR 8629, Dept Astrophys Relat & Cosmol, F-92195 Meudon, France Observ Paris Meudon France F-92195 elat & Cosmol, F-92195 Meudon, France
Titolo Testata:: ASTRONOMY & ASTROPHYSICS
fascicolo: 2, volume: 372, anno: 2001,
pagine: 535 - 543
SICI:: 1432-0746(200106)372:2<535:TCORSQ>2.0.ZU;2-3
Fonte:: ISI
Lingua:: ENG
Soggetto:: STABLE CIRCULAR ORBITS; X-RAY BINARIES; GENERAL-RELATIVITY; NEUTRON-STARS; STELLAR MODELS; MATTER; STATE;
Keywords:: dense matter; equation of state; stars : neutron; stars : rotation; stars : binaries : general;
Tipo documento:: Article
Natura:: Periodico
Settore Disciplinare:: Physical, Chemical & Earth Sciences
Citazioni:: 33
Recensione:
Indirizzi per estratti:: Indirizzo: Zdunik, JL Polish Acad Sci, N Copernicus Astron Ctr, Bartycka 18, PL-00716Warsaw, Poland Polish Acad Sci Bartycka 18 Warsaw Poland PL-00716 saw, Poland



Citazione:: J.L. Zdunik et al., "The crust of rotating strange quark stars", ASTRON ASTR, 372(2), 2001, pp. 535-543

Abstract

Calculations of the properties of rotating strange stars with crusts are performed within the framework of general relativity. We employ an equation of state (EOS) of strange quark matter based on the MIT Bag Model with massive strange quarks and lowest order QCD interactions. The crust is described by the BPS equation of state. A significant increase of the stellar radius is found close to the Keplerian (mass-shedding limit) configuration. Thisleads to the disappearance of the gap between the stellar surface and the innermost stable circular orbit (ISCO) at very high rotation rates, for a rather broad range of stellar masses. The Keplerian configuration for the strange star with crust corresponds to values of J, T/W, PISCO = 1/v(ISCO) which are about 20% smaller than in the case of bare strange stars. Because the Keplerian configuration is achieved due to the increase of the stellar oblateness, the Keplerian frequency (of the rotation) remains almost unaltered. The lack of the gap close to the Keplerian rotation could imply a more stringent limit on v(ISCO), if the existence of such a gap is supported by observations, as in the source 4U 1820-30 with the upper QPO frequency 1.07kHz. If such a constraint is taken into account (mandatory existence of a gap) the minimum v(ISCO) is about 1 kHz even with the extreme fine tuning of strange quark matter parameters. The minimum v(ISCO) is then obtained forthe non-rotating configuration with maximum allowable mass. The maximum frequency in the stable circular orbit around the strange star with a crust is smaller by about 100 Hz than in the case of a bare strange star. During the spin-down of a magnetized strange quark star with crust, the crust matter is absorbed in the equatorial region by the strange matter core. The deconfinement of absorbed crust matter is a strongly exothermic process, which would influence the cooling curve of this compact object.

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Documento generato il 26/05/13 alle ore 03:38:54