Browsing by Author "Sinha, Monika"

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    Astrophysical consequences of diquark formation on the surface of strange star
    (2001-05-12) Dey, Mira; Sinha, Monika; Ray, Subharthi
    Compactness of some stars is explained if they are strange stars (SS) as shown by Dey et al.(1998) (D98) and Li et al. (1999a,b). In D98, a realistic potential was used in a Fock mean eld approximation within Dirac phe- nomenology, thereby simplifying the spinorial structure of the quarks. Using the plane wave states for the beta equi- librated u, d and s quark Fermi seas from D98 and the conventional spin dependent force between these quarks, we now nd energy lowering in some speci c spin-aligned states. This is a short range pairing between quarks of dif- ferent flavours and may lower the energy by several MeV for each diquark pair. The accretion driven X-ray and γ ray bursts in com- pact objects are believed to be due to thermonuclear or some other explosions which are short lived. These may in fact destroy the spin alignment of the quarks if these stars are SS. The subsequent alignment and production of copious diquark pairing may produce su cient energy to produce recurrent very long bursts seen in some such stars. The long time involved in these processes, we claim, is due to the weak interactions which are responsible for the equilibration of strange quark matter. In such a the case the elusive properties of some of the most massive objects in nature, the compact stars, can be accounted for by spin alignment of pairs of the smallest components of matter, - namely the quarks.
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    Stability of strange stars (SS) derived from a realistic equation of state
    (2002-03-01) Sinha, Monika; Dey, Jishnu; Dey, Mira
    A realistic EOS (equation of state) leads to strange stars (ReSS) which are compact in the mass radius plot, close to the Schwarzchild limiting line [1]. Many of the observed stars fit in with this kind of compactness, irrespective of whether they are X-ray pulsars, bursters or soft γ repeaters or even radio pulsars. We point out that a change in the radius of a star can be small or large, when its mass is increasing and this depends on the position of a particular star on the mass radius curve. We carry out a stability analysis against radial oscillations and compare with the EOS of other SS models. We find that the ReSS is stable and an M-R region can be identified to that effect