共查询到20条相似文献，搜索用时 46 毫秒
1.
E. Van Hemelrijck 《Earth, Moon, and Planets》1987,38(3):209-216
In this short paper, the combined effect of global dust storms and the oblateness on the mean seasonal daily insolations at the Martian surface is investigated. Due to the flattening, the mean summertime insolation is increased at equatorial and low latitudes, decreased at mid- and high latitudes. When comparing a spherical with an oblate planet Mars, it is found that the percentage differences of the mean summer daily insolations are dependent upon the optical depths () considered. For an atmosphere without aerosols, the maximum percentage differences are respectively equal to + 0.05 and – 0.2%; at = 3.0 the corresponding values amount to about 0.1 and 2%. In winter, the mean daily insolations are decreased over the entire latitudinal interval, where the maximum values are found at polar region latitudes; at e.g. a latitude of 85 the loss of solar energy enhances from 2 ( = 0.0) to more than 30% ( = 3.0). The mean annual daily insolation is maximally reduced by about 0.5 and 2% for optical thicknesses of 0.0 and 3.0, respectively. 相似文献
2.
Hongnan Zhou 《Earth, Moon, and Planets》1989,46(3):233-241
We devised a numerical model of planetary ring in which the inelastic collision and the gravitation between ring particles are considered. We adopt Hill's equations and the differential algorithm of circular mesh for computation of the particle orbits. The evolutional processes are presented for different coefficient of restitution and dynamical optical depth . The results show that the semi-major axis and eccentricity of the ring particles are changed with and . We compute the average energies transferred and loss in inelastic collisions for various values of the parameters. The dynamical equilibrium properties are discussed in the different cases. 相似文献
3.
Detailed single and multiple scattering calculations were carried out for a spherically symmetric cometary atmosphere irradiated by a plane parallel source. Using simplifying assumptions in the single scattering approximation, analytical expressions were derived for the total flux impinging the cometary nucleus, which was shown to be a decreasing function of the coma opacity. Moreover, while highly anisotropic phase functions resulted in more light reaching the nucleus than was the case for isotropic phase functions, the net energy flux at the nucleus surface was still found to be smaller in the presence of a coma than in the no coma case. This increased flux due to the anisotropic phase functions was attributed mostly to the effect of directional scattering in the forward Sun-comet axis. The isotropic multiply scattered flux at the surface was found tobe an increasing function of the opacity, , for 2.5. At larger values of , the maximum in the downward directed scattered flux was still seen to increase, but occurred at a height of several radii above the nucleus, resulting in a reduction at the surface. On the other hand, the total flux at the surface was again shown to be a decreasing function of and always less than in the no coma case. Finally, on comparing the multiply scattered flux with that obtained in the plane parallel approximation, it was quite apparent that except in the vicinity of the Sun-comet axis, the plane parallel geometry tends to underestimate the degree of scattering.NRC Resident Research Associate. 相似文献
4.
W. E. Alnaser 《Earth, Moon, and Planets》1990,48(2):177-181
The clear sky emissivity 0 and the ground emissivity
g
in Bahrain is studied. The study reveals that the annual value of 0 is 0.88 ± 0.039 relating to the maximum and the minimum values in August and February, respectively. Meanwhile, the annual value of
g
is 0.338 ± 0.228, where the maximum and the minimum values are in July and January, respectively. These two parameters are related to the transmittance factor . 相似文献
5.
В. М. Чаругин 《Astrophysics and Space Science》1975,37(2):441-447
, . N/E, E
r, (E
r)=1. , (, ) . . 相似文献
6.
0–2 ( ). . . . 相似文献
7.
8.
A. A. Stepanian B. M. Vladimirsky Yu. I. Neshpor V. P. Fomin 《Astrophysics and Space Science》1975,38(2):267-282
The results of the observations to search gamma-ray sources with the energy greater than 2×1012 eV, which were made in Crimean Astrophysical Observatory during the years 1969–73 are presented. A technique of the detection of the EAS Cerenkov flashes was used.The quality of the data obtained is analysed. The criteria for the selection of the data free from meteorological variations are considered.It was shown that two objects, namely, Cyg X-3 and Cas -1, may be the sources of high-energy gamma quanta. It is probable that the object with the coordinates =05h15m, =+1° is the source of gamma-rays as well. An unidentified object Cas -1 is variable: gamma-ray flux was observed twice — in Sepember–October 1971 and in December 1972. It is possible that the flux from Cyg X-3 has a period of 4.8 hr.
I I , I I , - >2.1012 . I . I , I I, I ., - -1 Cyg -3- -I . , =0515 ·=+1° -.I -1 I: I J I- - 1971 1972 . Cyg -3, , - T=4.8 .相似文献
9.
E. E. Shnol 《Celestial Mechanics and Dynamical Astronomy》1984,33(2):159-167
The equilibrium point O of an autonomous Hamiltonian system of two degrees of freedom is considered for small-oscillation frequencies related as 2=21+. If under the precise resonance (=0) the equilibrium is unstable, the inner diameter () of the domain of stability containing the point O is estimated. It is shown that for the normalized variables ()/b where b is the corresponding resonance coefficient. The estimates () for other main resonances are reported. 相似文献
10.
The study of dynamics of the particle creation in relativistic viscous fluid in Robertson-Walker Universe is studied by using Brans-Dicke theory. The behaviour of these solutions with respect to Dirac's hypothesis are investigated along with the discussion of the physical parameters as well as the variable gravitational constant. By adopting a particular method of integration, exact solutions are obtained and physical interpretations are presented. 相似文献
11.
Kunitomo Sakurai 《Solar physics》1971,17(2):459-467
Except for protons, the chemical composition of solar cosmic rays is very similar to the abundance of the elements at the photosphere of the Sun. If we consider the relative abundance ratio of protons to -particles (P/) at constant rigidity, this ratio is highly variable from one solar cosmic ray event to another. This ratio observed at the Earth, however, decreases monotonically with time from the onset of solar flares and, furthermore, is dependent on the heliocentric distance of the parent flares from the central meridian of the solar disk. P/'s which have been measured before the onset of SC geomagnetic storms change from 1.5 to 50 or more, being a function of the westward position of the source from the east limb of the Sun. These variations with respect to time and heliocentric distance suggest that the propagation of solar cosmic rays is strongly modulated in the interplanetary space. The major part of the -particles seem to propagate as if they are trapped within the magnetic clouds which produce SC geomagnetic and cosmic ray storms at the earth.The chemical composition and rigidity spectra of solar cosmic rays suggest that solar cosmic rays are mainly accelerated by the Fermi mechanism in solar flares. The observed variation of P/'s is produced mainly through the difference between the propagation characteristics of protons and -particles.NAS-NRC Associate with NASA. 相似文献
12.
A. Hruška 《Astrophysics and Space Science》1977,50(1):153-161
One component of a three-fluid adiabatic plasma is under certain conditions contained in a restricted region of space by a large-scale electrostatic field generated within the plasma. The containment is discussed here for plasma consisting of ions and two populations of electrons characterized by different pitch angle distribution functions.The bouncing motion of electrons along open fieldlines between a magnetic mirror and an electrostatic mirror produces a velocity distribution function similar to that generated by bouncing particles on closed fieldlines. 相似文献
13.
Solar flares,microflares, nanoflares,and coronal heating 总被引：2，自引：0，他引：2
H. S. Hudson 《Solar physics》1991,133(2):357-369
Solar flare occurrence follows a power-law distribution against total flare energy W: dN/dW W
– with an index 1.8 as determined by several studies. This implies (a) that microflares must have a different, steeper distribution if they are energetically significant, and (b) there must be a high-energy cutoff of the observed distribution. We identify the distinct soft distribution needed for coronal heating, if such a distribution exists, with Parker's nanoflares.This paper considers a microflare to be a member of the normal X-ray burst population, with comparable physical parameters except for a smaller total energy. 相似文献
14.
15.
Two dimensional source brightness distributions at 26.4 MHz for solar bursts of spectral type II, III, IV, and V are derived from observations with a multiple-baseline, time-sharing interferometer system. It was designed explicitly to study the large angle (40 halo) component of low frequency solar bursts first reported by Weiss and Sheridan (1962). Thirty-two bursts occurring in the interval of June–August, 1975, were fit with a circular gaussian core and an elliptical gaussian halo component. Half-power halo diameters (E-W×N-S) averaged 30×28 for type III bursts and 42×27, 28×37, 30×25 for type V, II and IV bursts respectively. Typical core sizes fell in the range of 10±4 giving 31 halo to core size ratio. All burst types were found to have some large angle structure: the specific intensity was 10% compared to the core but the total power in each component was comparable. Two processes for producing the core-halo structure of type III bursts are compared: scattering and refraction of a point source and refraction from many sources over an extended region. It is concluded that the core can be explained by either model but the halo is more consistent with emission from an extended source region of 40° in longitude. 相似文献
16.
S. N. Osipov 《Solar physics》1985,102(1-2):29-32
The blanketing effect for the solar disc center and its value near the limb (cos = 0.23) are obtained for the rocket ultraviolet region using the Harvard center and limb spectra. The value of for the disc center appears to be 0.67 (on average) relative to the quasicontinuum. The essential decrease of towards the limb is also revealed. 相似文献
17.
Intermediate resolution (/ 25 000) CCD spectra of the oxygen triplet at 7770 Å have been analyzed to determine oxygen abundances in a sample of metal-deficient stars with metallicities covering the range –2.5[Fe/H]–0.2. Important oxygen overabundances ([O/Fe]1) are found in the more metal deficient stars of the sample. We briefly discuss the information that these observations provide about the early nucleosynthesis history and chemical evolution of the Galaxy. 相似文献
18.
The assumption of a linearly expanding universe for the JBD-cosmological equations generates a set of solutions for the barotropic equations of statep= (=const.). These solutions turn out to be valid for closed space-except in the casep= which is for open space. The gravitational constant which is inversely proportional to the scalar field increases with time if >–1/3 and decreases for <–1/3. No solution exists for =1/3. The Brans-Dicke parameter is negative if <–1/3. 相似文献
19.
R. Muller 《Solar physics》1977,52(2):249-262
From time series of high resolution photographs, morphological properties of the photospheric facular granules were derived. The facular granules are cells of the common granular pattern, brighter than the normal granules when seen between cos = 0.6 and the limb. Their apparent diameter, which decreases towards the limb, is smaller than that of the normal granules: 0.65 and 1.25 respectively at cos = 0.55; their lifetime is 25 min but their bright stage lifetime is only 15 min; they are visible closer to the limb than the normal granules: 1.2 compared to 2–5; the brightening of the facular granules occurs at a faster rate than their fading. From the great similitude of both morphological properties and temperature models of facular and normal granules, it appears possible that the photospheric facular granules are convective cells modified by the presence of a magnetic field of some hundreds Gauss. 相似文献
20.
Robert M. Wilson 《Solar physics》1986,106(1):29-33
Mt. Wilson numbers of spots data (as defined in Howard et al., 1984) appear to be distributed according to even-odd cycle numbering. Linear fits of annual numbers of spots versus annual sunspot number for even- and odd-numbered cycles have slopes which are statistically different at the 5% level of significance. The existence of an even-odd split in Mt. Wilson numbers of spots data may be due either to a real difference in even- and odd-numbered cycles on the Sun or to a difference in weather at Mt. Wilson (perhaps, related to the 22-yr rhythm of drought in the western United States) during even- and odd-numbered cycles, or both. For cycle 22, an even-numbered cycle, the peak numbers of spots is estimated to be near 2600. 相似文献