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1.
A further development of the Kostyuk-Pikelner's model is presented. The response of the chromosphere heated by non-thermal electrons of the power-law energy spectrum has been studied on the basis of the numerical solution of the one-dimensional time-dependent equations of gravitational gas dynamics. The ionization and energy loss for the emissions in the Lyman and Balmer lines have been determined separately for the optically thin and thick L-line layers. Due to the initial heating, a higher-pressure region is formed. From this region, disturbances propagate upwards (a shock wave with a velocity of more than 1000 km s-1) and downwards. A temperature jump propagates downwards, and a shock is formed in front of the thermal wave. During a period of several seconds after the beginning of this process, the temperature jump intensifies the downward shock wave and the large radiative loss gives rise to the high density jump (
2/
1 100). The numerical solution has been analyzed in detail for the case heating of the ionized and neutral plasma, and a value of this heating is close to the upper limit of the admissible values. In this case, the condensation located between the temperature jump and the shock wave front, may emit in the observed optical continuum.In their essential features, the gas dynamic processes during the flares in red dwarf atmospheres are the same as those in the solar atmosphere. However, the high atmospheric densities, smaller height scale in red dwarf atmospheres, and greater energy of this processes in stellar flares, give rise, in practice, to the regular generation of optical continuum. The photometric parameters of a source with n 015 cm-3, T 9000 K, and
z 10 km are in a good agreement with observations. 相似文献
2.
The rotation of the solar corona is analyzed using the original database on the brightness of the FeXIV 530.3 nm coronal green line covering six recent activity cycles. The rate of the differential rotation of the corona depends on the cycle phase. In decay phases, there are only small differences in the rotation, which are similar to that of a rigid body. The differences are more significant (though less pronounced than in the photosphere) during rise phases, just before maxima, and sometimes at maxima. The total rate of the coronal rotation is represented as a superposition of two, i.e., fast and slow modes. The synodic period of the fast mode is approximately 27 days at the equator and varies slightly with time. This mode displays weak differences in rotation and is most pronounced in the middle of decay phases. The slow mode is manifested only at high latitudes during the rise phases of activity, and displays a mean period of 31 days. The relative contribution of each mode to the total rotational rate is determined as a function of time and heliographic latitude. These results indicate that the structure of the velocity field in the convective zone must also vary with time. This conclusion can be verified by helioseismology measurements in the near future. 相似文献
3.
We consider the adequacy of various solar coronal heating models. We show that the correlation between the intensity of the coronal Fe XIV 530.5 nm green line and the calculated magnetic field strength in the solar corona can be a useful tool for this purpose. We have established this correlation for coronal structures and magnetic fields of large spatial and temporal scales. The correlation found exhibits a strong dependence on both solar cycle phase and heliolatitude. The efficiency of a particular coronal heating mechanism is probably determined by the relative area occupied by low and high loops (including open structures). The direct current models based on slow field dissipation (DC) and the wave models based on Alfvén and magnetosonic wave dissipation (AC) are more efficient in the equatorial and polar zones, respectively. 相似文献
4.
V. D. Badalyan 《Astrophysics》2006,49(4):538-542
The angular dependence of the reflection coefficient is studied for electromagnetic waves passing through a one-dimensional
quasiperiodic dielectric layer. It is found that for certain types of quasiperiodic systems, omnidirectional reflection of
electromagnetic waves can occur.
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Translated from Astrofizika, Vol. 49, No. 4, pp. 631–636 (November 2006). 相似文献
5.
Synoptic maps of the intensity of the λ530.5 nm FeXIV green coronal line and maps of computed coronal magnetic fields for the period 1977–2001 are compared. For quantitative comparisons, the correlation coefficients r for the correlation between these two parameters at corresponding points of the synoptic maps are calculated. This coefficient exhibits cyclic variations in the spot-formation zone, ±30° and the zone above 30° and is in antiphase in these two zones. In the low-latitude zone, the correlation coefficient is always positive, reaches its maximum at activity minimum, and strongly decreases by activity maximum. Above 30°, r reaches maximum positive values at activity maximum and then gradually decreases, passing through zero near the beginning of the phase of activity minimum and becoming negative during this phase. A Fourier analysis of r as a function of time reveals a wavelike variation with a period close to 1.3 yr (known also from helioseismological data for the tachoclinic region of magnetic-field generation), as well as a pronounced wave with a period of about 5 yr. The latitude dependence of r seems to be related to variations in the contributions from local, large-scale, and global fields. Our analysis suggests an approach to studying the complex problem of mechanisms for coronal heating. 相似文献
6.
O. G. Badalyan 《Astronomy Reports》2011,55(10):928-942
The temporal variations observed in the monthly mean latitudes of sunspot groups are studied over 1874–2010 using the data
of the Greenwich Catalog and its NOAA-USEF extension. The 11-year cycle is quite clear in the temporal variations of the monthly
mean latitudes of sunspot groups (i.e., of the centers of spotting) in both the northern and southern hemispheres. The North-South
(N-S) asymmetry in the latitudes of sunspot groups defined as the difference between the absolute values of sunspot latitudes
observed in the N and S hemispheres is compared with the N-S asymmetry in the total area of sunspot groups determined on the
scales of 11 years and longer. The N-S asymmetry is interpreted as an imbalance in the hemispheres’ powers (asymmetry in the
total area of sunspot groups) and as spatial imbalance (asymmetry in the latitudes of the centers of spotting). This imbalance
is most clearly seen at the solar minima, i.e., in the gradual transition from one cycle to the other, when the absolute values
of the asymmetries observed both in the total sunspot area and in the sunspot latitudes reach their maxima. The results obtained
here can be helpful for analyses of the solar dynamo. 相似文献
7.
An analytical expression is obtained for the K-corona brightness as a function of the distance from the solar limb. The agreement of the theory with the numerous observational data indicates that the density distribution at the levels located at 1.2–2.5 R
heliocentric distances may be treated as hydrostatic with T = const. The deviation of the observed K-corona brightness from the expression obtained may be indicative of supersonic fluxes of matter. These concepts may be used to verify the various theoretical models for solar wind source. 相似文献
8.
The spatial and temporal brightness distributions of the Fe XIV 530.3 nm coronal green line (CGL) and cyclic variations of these distributions are analyzed for a long time interval covering more than five 11-year cycles (1943–2001). The database of line brightnesses is visually represented in the form of a movie. Substantial restructuring of the spatial distribution of the CGL brightness occur over fairly short time intervals near the so-called reference points of the solar cycle; such points can be identified based on various sets of solar-activity indices. Active longitudes are observed in the CGL brightness over 1.5–3 yr. Antipodal and “alternating” active longitudes are also detected. The movie can be used to compare the CGL brightness data with other indicators of solar activity, such as magnetic fields. The movie is available at http://helios.izmiran.rssi.ru/hellab/Badalyan/green/. 相似文献
9.
Profiles of weak Fraunhofer lines have been recorded photoelectrically in both the faculae and the undisturbed photosphere. The entrance slit of the double-pass spectrograph corresponded to 1 × 20 on the solar disk. Turbulent velocities were found by comparing half-widths of the observed profiles with those of model calculations. These latter were carried out with aid of an electronic computer for the Bilderberg Continuum Atmosphere (BCA) under the assumption of true absorption and depth independent turbulent velocities. Line-formation levels were derived from the contribution curves computed by the method of weighting functions. For the undisturbed photosphere a turbulent velocity of about 2.6 km/s was found with no appreciable increase with the depth. In facular filaments all lines formed above = 0.1 showed smaller turbulence velocities, the velocity differences being in the range between 0.2 and 0.6 km/s (see Table II). 相似文献
10.
Distributions of brightness and polarization,p, were obtained for the February 16, 1980 solar corona. Isophotes have a circular shape, typical for the period of the solar cycle maximum. A variety of structural features are distinctly seen in the distribution ofp. The polarization reaches 55%, and thep values are comparatively high, not only in the well-defined streamers, but in the overlapping faint rays and small streamers, as well. A theoretical interpretation of the observed high degrees of polarization, taking into account the data on coronal brightness, is very difficult. This cannot be done within the scope of spherically symmetric models of the corona; the assumption of a high concentration of coronal matter into the plane of the sky is needed. With the most extreme densities in coronal structures, it is not, however, possible to exceed the observed valuep = 55%. Taking into account the accuracy of the polarization measurements, there are no reasons to reject the Thomson scattering as a basic mechanism to explain the origin of the white-light corona. 相似文献