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1.
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The evolution of a 20M star of extreme Population I (X=0.602,Z=0.044) from the main sequence through the He-exhaustion has been calculated with particular attention to the treatment of the semiconvective zones. Two different relations as convective instability criteria have been adopted R a +(/(4–3)) (d ln /d lnP) or R a ). The He-burning phase is substantially different in the two cases. In the first evolutionary picture the star begins the He-burning phase as red supergiant, while in the second one as blue supergiant. The two evolutions are compared with the observational blue to red supergiants ration B/n R in connection with the problem of the existence of the neutrino processes and taking into account the possible presence of a high percentage of binary systems among supergiants.We draw the conclusion that the massive star evolution seems to be still completely uncertain and also not able to give a decisive test for or against the neutrino emission.  相似文献   

3.
In this paper we calculate the number of close binaries formed during the evolution process of a globular cluster core. The globular cluster core is assumed to contain a massive black hole at its center. We show that the central black hole can drive binaries formation in the core and the rate of binaries formation depends on the mass of the black hole at its center. When the massM of the black hole is between 102 M and 3×103 M , there will be a few binaries formed. When the mass of the black hole is 4×103 M M6×103 M , the number of binary star formation will suddenly increase with a jump to the maximum value 58. When the mass of the black hole is 7×103 M M9×103 M , the number of binary star will immediately decrease. Whether cluster X-ray is produced mainly by the central black hole or by binaries in the core depends on the mass of the central black hole. Therefore, two cases arise: namely, black hole accretion domination and binaries radiation domination. We do think that we cannot exclude the possibility of the existence of a central black hole even when binary radiation characteristics have been observed in globular cluster X-ray sources.  相似文献   

4.
L. Staveland 《Solar physics》1974,36(1):235-238
An analytical expression for the limb profile and the aureole is derived for a Gaussian spread function with b 2. Power series with 3 terms are used as approximation to the limb darkening given by HSRA (Gingerich et al., 1971). For smaller values of the spread parameter b the expression given by Staveland (1972) gives a more correct result. The rms difference in the intensity is 0.005 between these analytical expressions and a numerical integration (Brahde, 1972) both inside and outside the limb. Mullan's (1973) expression gives too low intensities in the range ±2b around the limb.  相似文献   

5.
The process of re-escalation of the scalar field as R 3, the energy density as R 3, and the pressurep aspR 3P, lends itself to obtain a reduced equation that represents, for a wide variety of equations of state, the cosmological evolution of an homogeneous and isotropic, flat Universe. A particular solution to this equation is presented.  相似文献   

6.
On the basis of more abundant data a relation logPV/logR for cepheid variables (Fernie, 1965) is constructed. A linear relation between logP V and logR for classical cepheids is found, which perhaps has a break at R=10R . On the logR/logP diagram thes-cepheids (Efremov, 1968) show a distinct sequence. Alls-cepheids present a relative variation of the radii R/R0.075. The existence of non-s-cepheids with R/R0.075 raises a point about the evolutionary place of these stars (see Efremov, 1968). One could suppose that cepheids with logP>1.1 pulsate in the first overtone.  相似文献   

7.
Linear limb-darkening coefficientsu required in the analysis of eclipsing binary curves, are tabulated for a wide range of effective temperature (50 000° to 4000°), wavelength (0.2 2.2 ), and gravitiesg (2.0logg5.0). The computation is based on the comprehensive range of model atmospheres of Carbon and Gingerich (1969).The results are compared with the theoretical values of Hosokawa (1957), Kopal (1959) and Grygaret al. (1972), and examined in relation to empirically determined values ofu from analyses of eclipsing binary light curves. An improved agreement between theory and observation for the calculated limb-darkening coefficients of the present work is noted.  相似文献   

8.
In this paper we introduce a new parameter, the shear angle of vector magnetic fields, , to describe the non-potentiality of magnetic fields in active regions, which is defined as the angle between the observed vector magnetic field and its corresponding current-free field. In the case of highly inclined field configurations, this angle is approximately equal to the angular shear, , defined by Hagyardet al. (1984). The angular shear, , can be considered as the projection of the shear angle, , on the photosphere. For the active region studied, the shear angle, , seems to have a better and neater correspondence with flare activity than does . The shear angle, , gives a clearer explanation of the non-potentiality of magnetic fields. It is a better measure of the deviation of the observed magnetic field from a potential field, and is directly related to the magnetic free energy stored in non-potential fields.  相似文献   

9.
Stewart  R. T.  Howard  R. A.  Hansen  F.  Gergely  T.  Kundu  M. 《Solar physics》1974,36(1):219-231
Observations of a coronal disturbance on 1973 January 11 commencing at 18h01m UT are described. The event is homologous with an earlier disturbance from the same region of the corona. The observations suggest that a cloud of coronal gas containing 4 × 1039 electrons propagated outwards to 5 R behind a piston-driven shock wave travelling at a velocity of 800 to 1200 km s–1.On leave from Division of Radiophysics, CSIRO, Sydney, Australia.  相似文献   

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. - . . , . - . - , , , -. ., , .
The structure of rotating magnetic polytropes is considered in Roche approximation. Investigation of the influence of poloidal as well as toroidal magnetic fields on the conditions of the beginning of matter outflow due to rotational instability is carried out. The influence of the turbulent convection and twisting of magnetic force-lines on the time of smoothing of differential rotation is considered. The estimate of the magneto-turbulence energy generated by differential rotation is presented. Both maximum possible energy output and duration of the quasi-statical evolution phase up to the appearance of hydrodynamic instability due to the effects of general relativity are calculated for supermassive magnetic polytropes of index three with uniform or differential rotation. The radius-mass relation is obtained for supermassive differentially-rotating magnetic polytropes referring to the longest part of the quasi-statistical evolution stage; some consequences are pointed out, including the period-luminosity relation.The evolution of the considered models of supermassive rotating magnetic polytropes with different character of rotation and different geometry of a magnetic field is discussed.The results obtained are summarized in the last section.


English translation will appear in the next issue ofAstrophys. Space Sci.

Receipt delayed by postal strike in Great Britain  相似文献   

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We give the fifth list of red stars of the First Byurakan Spectral Sky Survey. The objects are located in the zone 5h 18h 30m and +65 +69. The list contains the data on 18 new objects, one of which is a star of class R. We also give the first determination of the spectral class of 11 variable objects, for four of which we give the spectrograms in the range of wavelengths 4700–6700å.Translated fromAstrofizika, Vol. 37, No. 4, 1994.  相似文献   

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Based on a general planetary theory, the secular perturbations in the motion of the eight major planets (excluding Pluto) have been derived in polynomial form. The results are presented in the tables. The linear terms of second order with respect to the planetary masses and the nonlinear terms of first order up to the fifth (and partly seventh) degree with respect to eccentricities and inclinations were taken into account in the right-hand members of the secular system. Calculations were carried out by computer with the use of a system that performed analytic operations on power series with complex coefficients.
qA ( ). . ( ) . .
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20.
, ii (2000–3000 Å) i . , i . i (. 2). i i i i + ( 7–10). ii (. 13). ii i i (, 2400 Å) (. 14 15). i i i , iu , i (. 1). i i ii i i . .  相似文献   

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