1993年咸宁地震群震害损失及发震成因探讨

1993年7~8月,湖北省咸宁地区发生了一系列ML≤4.1的地震。从地震系列、地表破坏状况和地震宏观等烈度线展布特征出发,深入研究了地震与地质构造及地下水动态变化的关系,得出结论地震群可能为抽取地下水引起的构造变动而诱发。     

Strange quark matter and models of strange stars

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.     

Variations of cosmic-ray energy in interplanetary space

A consistent theory of energy exchange between high-energy charged cosmic-ray particles and the random inhomogeneities of a magnetic field frozen in the moving solar wind plasma is developed. It is shown that the mode of the particle energy variations at a given law of plasma velocity variation in space is determined by the specific form of the particle distribution function. The equation for the density of cosmic-ray energy is obtained. Consideration is given to the generation of a charged particle energy spectrum in the course of multiple scatterings by the random inhomogeneities of the magnetic field.     

Hydrodynamical models of type II supernovae

A series of hydrodynamical models of type-II supernova outbursts (SNII) has been calculated. Approximate relations connecting the total outburst energy ε, the mass of envelope ejectedM, the presupernova radiusR, and the amount of ionizing quanta radiated by the supernovaeN _H with such values as the duration of the light curve plateau Δt, and absolute magnitude in the wavelength bandV and photospheric velocityU _PH observed near the middle of the plateau have been established. Advantage has been taken of the relations to obtain a preliminary evaluation for the characteristics of the average SN II: ε=7×10⁵⁰ erg,M=6M _⊙,R=500R _⊙,N _H=2×10⁵⁸. The SNIIs with plateau-like light curves seem to be accounted for by thermonuclear explosions of degenerate cores of red giant stars and result in a total disruption of the star without any stellar remnant. To the contrary, SNIIs with linear light curves have substantially different properties (in particular, they throw considerably less massive envelopes off). These SNII must signify the birth of collapsed objects—neutron stars (pulsars) or black holes.     

中等贫金属星的元素丰度分析

给出 １１颗中等贫金属星－１．３ ５［Ｆｅ／Ｈ］ ≤－０．６的观测资料,确定了这些样本星的恒星大气参数,得到了这些星中１４种元素的丰度．讨论了各类元素丰度比随金属丰度的变化。α元素（Ｍｇ、 Ｓｉ、 Ｃａ、 Ｔｉ）相对于铁均表现超丰,每一金属丰度处都存在不同程度的弥散．大部分的铁峰元素（Ｖ、Ｃｒ、Ｎｉ、Ｃｕ）也相对于铁超丰,不随［Ｆｅ／Ｈ］而变化,而［Ｍｎ／Ｆｅ］则随金属丰度的增加而增加．［Ｎａ／Ａｌ］在［Ｆｅ／Ｈ］＞－１．１的样本星中表现超车,在［Ｆｅ／Ｈ］＜－１．１的样本中却明显过贫．     

Electromagnetic radiation outbursts from the collision of P/Shoemaker-Levy 9 comet with Jupiter

The forthcoming collision by debris of P/Shoemaker-Levy 9 comet with Jupiter during the week of July 18, 1994 has generated considerable scientific and public interest. This collision may release an amount of energy ranging from 10²⁵-10³¹ ergs in the Jovian atmosphere. Two possible phenomena associated with this event are described in this Letter to the Editor. The first one is the likely display of deformed Jovian magnetic field lines as the comet interacts with the Jovian magnetosphere. The second one is electromagnetic radiation outbursts during comet explosions over a wide frequency range from radio up to gamma ray emissions. If relativistic electrons with energies up to ~ 1000 MeV could be produced during comet explosions, then synchrotron radiations with frequencies from radio up to infrared range could be detectable. Hard X-rays and gamma rays could be produced by bremsstrahlung and inverse Compton processes. Since one cannot exclude the possible transient presence of relativistic electrons with Lorentz factor 2 × 10⁶, synchrotron radiation component might even be extended into gamma ray frequency range during intermittent short time intervals.     

A Critical review of theoretical models of negatively polarized light scattered by atmosphereless solar system bodies

About a dozen physical mechanisms and models aspire to explain the negative polarization of light scattered by atmosphereless celestial bodies. This is too large a number for the reliable interpretation of observational data. Through a comparative analysis of the models, our main goal is to answer the question: Does any one model have an advantage over the others? Our analysis is based on new laboratory polarimetric and photometric data as well as on theoretical results. We show that the widely used models due to Hopfield and Wolff cannot realistically explain the phase-angle dependence of the degree of polarization observed at small phase angles. The so-called interference or coherent backscattering mechanism is the most promising model. Models based on that mechanism use well-defined physical parameters to explain both negative polarization and the opposition effect. They are supported by laboratory experiments, particularly those showing enhancement of negative polarization with decreasing particle size down to the wavelength of light. According to the interference mechanism, pronounced negative branches of polarization, like those of C-class asteroids, may indicate a high degree of optical inhomogeneity of light-scattering surfaces at small scales. The mechanism also seems appropriate for treating the negative polarization and opposition effects of cometary dust comae, planetary rings, and the zodiacal light.     

Observations of radio emission from the cosmic gamma-ray burst GRB 030329

We present the radio observations of the afterglow from the intense cosmic gamma-ray burst GRB 030329 performed with the radio telescopes of the Institute of Applied Astronomy, Russian Academy of Sciences, at the Svetloe (λ=3.5 cm) and Zelenchuk (λ=6 cm) Observatories. The difference between the fluxes measured in two different polarization modes suggests the existence of a circular polarization in the radio afterglow from GRB 030329. However, since the measurement errors of the fluxes with different circular polarizations are large, we cannot draw a firm conclusion about its detection; we can only set an upper limit on its value. An analysis of the possible generation mechanisms for the circular polarization of the relativistic jet suggests that there is a helical magnetic field in the jet. The existence of significant flux densities at various wavelengths during a long (≥10 days) period leads us to conclude that the hydrodynamic evolution of the relativistic bow shock takes place in the stellar wind, not in the interstellar medium. We have estimated the total GRB energy (E=10⁵¹ erg) (under the assumption of isotropic radiation) and the plasma density of the stellar wind from the presupernova (n=3 cm^?3). The magnetic-field strength in the relativistic jet can be estimated as B≈100 G.