Strange quark matter and models of strange stars     

Yu. L. Vartanyan  A. R. Arutyunyan  A. K. Grigoryan 《Astrophysics》1994,37(3):271-280

In the framework of the MIT bag model we consider absolutely stable strange quark matter consisting of u, d, and s quarks and electrons. For a realistic range of parameters of the quark bag we compute the threshold density for the appearance of strange quark matter that is realized on the surface of self-sustaining strange stars. On the basis of twelve calculated equations of state we give a detailed study of the series of configurations of strange stars consistent with the best known observational data. We show that the binding energy of the models depends essentially on the quark-gluon interaction constant _c.Translated fromAstrofizika, Vol. 37, No. 3, 1994.The authors are grateful to E. V. Chubaryan and A. M. Atoyan for assistance in overcoming the information blockade. The present paper was written in the framework of area 46/101 93-353, supported by the Ministry of Higher Education and Science of the Republic of Armenia.  相似文献   

A red giant with a strange star as its core. Principal similarities to and differences from Thorne-Zytkow objects     

G. S. Hajyan  Yu. L. Vartanyan  A. K. Grigoryan 《Astrophysics》1998,41(4):349-355

A model red giant with a mass of 5 M_⊙ a luminosity of 41,740 L_⊙, and a radius of 960 R_⊙ and with a strange quark star as its core is constructed, and it is compared with a Thorne-Zytkow object having similar integrated parameters. The difference in internal structure is manifested right at the dense core: matter above the core is held off only by γ rays from the strange star, and convection is maintained down to the strange star. The lifetime of a red giant containing a strange star turns out to be almost 500 times shorter than that of a Thorne-Zytkow object — on the order of 10⁵ years. Translated from Astrofizika, Vol. 41. No. 4, pp. 533–544, October–December, 1998.  相似文献   

The global endo-drainage system: Prospects of seismic prediction     

G. S. Vartanyan 《Izvestiya Atmospheric and Oceanic Physics》2013,49(7):745-759

Any natural phenomenon (process) occurs, develops, and dies away within a specific environment. Therefore, a study of its development patterns and forecast of its occurrence or extinction requires thorough knowledge of the host environment. In view of this, we have considered some characteristic features of the structure and functioning of the global endo-drainage system (GEDS) as a geological medium where all the seismic zones are concentrated and most of the major earthquakes in the world occur. We have described the basic principles of regional hydrogeodeformatics, which gives a methodology for the strain-field monitoring of extensive geological objects aimed at the short-term prediction of strong and devastating earthquakes. Based on data from long-term monitoring over the evolution of the earth’s hydrogeodeformation (HGD) field, we show some examples of possible earthquake predictions.  相似文献   

Neutron Stars with a Quark Core. II. Basic Integral and Structural Parameters     

G. B. Alaverdyan  A. R. Harutyunyan  Yu. L. Vartanyan 《Astrophysics》2004,47(1):52-64

A broad sample of computed realistic equations of state of superdense matter with a quark phase transition is used to construct a series of models of neutron stars with a strange quark core. The integral characteristics of the stellar configurations are obtained: gravitational mass, rest mass, radius, relativistic moment of inertia, and red shift from the star's surface, as well as the mass and radius of the quark core within the allowable range of values for the central pressure. The parameters of some of the characteristic configurations of the calculated series are also given and these are studied in detail. It is found that a new additional region of stability for neutron stars with strange quark cores may exist for some models of the equation of state.  相似文献   

Neutron stars     

Yu. L. Vartanyan  G. B. Alaverdyan 《Astrophysics》1989,31(1):482-489

Erevan State University. Translated from Astrofizika, Vol. 31, No. 1, pp. 111–123, July–August, 1989.  相似文献   

Evolution and radial pulsations of isothermal white dwarfs with allowance for rotation,neutronization, and general relativity theory     

Yu. L. Vartanyan  A. V. Ovsepyan 《Astrophysics》1971,7(1):62-69

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Intrinsic polarization of stellar light from RX Boo,AB Cyg,AK Peg     

R. A. Vartanyan 《Astrophysics》1968,4(1):51-51

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Global Endodrainage System: Fluid Geodynamics of Strong Crustal Earthquakes     

Vartanyan  G. S. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(11):1436-1460

Izvestiya, Atmospheric and Oceanic Physics - The substance of which our planet is composed is constantly and variously transforming. The most active processes in the evolution of the Earth’s...  相似文献   

Strange stars and their cooling with positron electrical neutralization of quark matter     

G. S. Hajyan  Yu. L. Vartanyan  A. K. Grigoryan 《Astrophysics》1999,42(4):467-476

Questions of the equilibrium, stability, and observational manifestations of strange stars are considered, in which electrical neutralization of the quark matter is provided by positrons, as occurs for some sets of bag parameters resulting in a stiffer equation of state. Such models consist entirely of self-contained, strange quark matter and their maximum mass reaches 2.4–2.5 M_⊙ with a radius of 13–14 km. The cooling of such strange quark stars both in the absence and in the presence of mass accretion is investigated. It is shown that in the absence of mass accretion onto the strange star, the dependence of temperature (T, K) on age (t, yr) depends very little on the mass of the configuration and has the form T ≈ 2.3·10⁸r^−1/5. If the star’s initial temperature is sufficiently high (T₀≥2·10¹⁰K), then the total number of electron-positron pairs emitted does not depend on it and is determined only by the total mass of the configuration. In the case of accretion, the annihilation of electrons of the infalling fatter with positrons of the strange quark matter results in the emission of γ-rays with an energy of∼0.5 MeV, by observing which one can distinguish candidates for strange stars. The maximum temperature of strange stars with mass accretion is calculated. Translated from Astrofizika, Vol. 42, No. 4, pp. 617–630, October–December, 1999.  相似文献   

On the mass defect of strange stars     

Yu. L. Vartanyan  A. K. Grigoryan  G. A. Khachatryan 《Astrophysics》1995,38(2):152-156

In the context of the MIT bag model we compute the mass defect and the gravitational packing factor for three models of strange stars and study the contribution of gravitational and internal energy to the total energy of the system. For strange stars it is possible to realize a model with negative internal energy, leading to a greater binding energy of these stars compared to neutron stars. This is the reason for the absence of configurations with negative mass defect for the models in question. We analyze the question of identifying the remnants of supernovae with neutron or strange stars.Translated fromAstrofizika, Vol. 38, No. 2, 1995.  相似文献