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1.
Bianchi Type I magnetized string cosmological model following the techniques used by Letelier and Stachel, is investigated.
To get a determinate model, we assume a condition ∊ = λ (geometric string) where ∊ is the rest energy density, λ the string
tension density and expansion (θ) is proportional to eigen value σ1
1 of shear tensor (σ
j
i
), which leads to A = ℓ (BC)
n
where A, B, C are metric potentials and ℓ and n are constants. The behaviour of the model in presence and absence of magnetic field is discussed. The physical and geometrical
aspects of the model are also discussed. 相似文献
2.
Photoelectric observations of WX Eridani inB andV filters have been discussed. The maximum magnitudes of the system areB=9
m
.70 andV=9
m
.46. TheB-V colours of the components are 0
m
.16 and 0
m
.80 for the primary and the secondary, respectively, while their spectral types are A5+K0. The period has been found to be constant and its revised value is 0d.823 270 76. 相似文献
3.
Photometric observations of primary minimum inU, B, andV filters have been discussed. The amplitude of variation in all the three filters is 0
m
.66. We do not find variations in the period and its revised value is 1d.0047115. 相似文献
4.
Photoelectric observations of FW Monocerotis inU,B, andV filters have been discussed. The depths of the primary minimum inU BV colours are 2
.
m
63, 2
.
m
17 and 1
.
m
76, respectively. No variation in the period has been found and its revised value is 3
.
d
8735868. 相似文献
5.
Cao Shenglin 《Astrophysics and Space Science》1990,174(2):165-171
According to our Paper I (Cao Shenglin, 1988), it could be supposed that the physical space-time is a Finsler space-time, characterized by the metric ds
4=g
ijkf
dx
i
dx
j
dx
k
dx
f
. If so, a new space-time transformation could be found by invariant ds
4 and the theory of relativity is discussed on this transformation.The project supported by National Natural Science Foundation of China. 相似文献
6.
The integrated magnitudes of 221 Galactic open clusters have been used to derive the luminosity function. The completeness
of the data has also been discussed. In the luminosity distribution the maximum frequency of clusters occurs nearI (Mv) = −3
m
.
5, and some plausible reasons for a sharp cut-off atI (Mv) = −2m. 0 have been discussed. It is concluded that the paucity of the clusters fainter thanI (M
v) = −2
m
.0
is not purely due to selection effects. The surface density of the clusters for different magnitude intervals has. been obtained
using the completeness radius estimated from the logN- logd plots. A relation betweenI (Mv) and surface density has been obtained which yields a steeper slope than that obtained by van den Bergh & Lafontaine (1984). 相似文献
7.
Bianchi Type I string dust cosmological models in presence and absence of magnetic field following the techniques used by
Letelier and Stachel, are investigated. To get the deterministic solution, we have assumed that σ
11 is proportional to the expansion (θ) where σ
11 is the eigen value of shear tensor (σ
i
j
) and which leads to A=N(BC)−n
, n>0 where A,B,C are metric potentials and
, N and ℓ are constants. The behaviour of the models in presence and absence of magnetic field are discussed. The other physical and
geometrical aspects of the model are also discussed. 相似文献
8.
Some Bianchi Type IX string cosmological models with bulk viscous fluid for massive string is investigated. To get a determinate
solution, a supplementary condition a=b
n, between metric potentials, is used wherea and b are function of time alone. A particular solution for n=0 is also discussed. The behaviour of the model in presence and absence
of bulk viscosity, is discussed. The physical and implications of the model is also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Atomic self consistent field calculations are applied to identify Fe VI and Fe VII spectra belonging to the 3p
6 3d
n — 3p
5 3d
n + 1 transition arrays. Their presence in vacuum spark spectra and absence in solar spectrograms is discussed. 相似文献
10.
In this paper, we have investigated some tilted Bianchi Type I models with heat conduction filled with disordered radiation
of perfect fluid. To get a determinate solution, we have assumed a condition A =(BC)
n between metric potentials. Alternatively we have discussed the case A=(BC)
1/3 for which tilted nature of the model is preserved. The various and geometrical features with singularities in the models
are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
The paper considers a homogeneous Bianchi type II universe. Under each of the conditionsC
hijk
C
hijk
=0 and*
C
hijk
C
hijk
=0 different types of models have been studied and their physical and kinematical properties have been discussed. 相似文献
12.
13.
Cylindrically symmetric inhomogeneous string cosmological model in presence of electromagnetic field is investigated. We have
assumed that F
23 is the only non-vanishing component of F
ij
. To get the deterministic solution, it has been assumed that the expansion (θ) in the model is proportional to the eigen value σ
1
1 of the shear tensor σ
i
j
. The physical and geometric aspects of the model are also discussed.
相似文献
14.
Cao Shenglin 《Astrophysics and Space Science》1992,190(2):303-315
According to the different properties between the ds
2 and the ds
4, it is discussed that the space-time will have the catastrophe nature on the Finsler metric ds
4 (see Cao, 1990, Paper II). The space-time transformations and the physical quantities will suddenly change at the catastrophe theory of the space-time. It will be supposed that only the dual velocity of the super-luminal-speed could be observed (see Cao, 1988). If so, a particle with the super-luminal-speedv>c, could be regarded as its anti-particle with the dual velocityv
1=c
2/v<c.The project was supported by National Natural Science Foundation of China. 相似文献
15.
Theoretical populations of the 2s3l levels of Ne vii are presented for electron temperatures from 2.5 × 105 K to 4 × 106 K and electron densities from 108 cm–3 to 1012 cm–3. These, in conjunction with intensities of previously observed solar Ne vii lines and wavelengths and intensities observed in the laboratory, are used to identify further Ne vii lines in the solar spectrum. The dependence on temperature of intensity ratios such as I(2s2p
1
P – 2s3d
1
D)/I(2s2p
3
P – 2s3d
3
D) is demonstrated and the advantages of the small wavelength separation of such lines for solar electron temperature diagnostics are discussed. 相似文献
16.
J.-René Roy 《Solar physics》1976,48(1):149-158
Observations of a surge prominence event on 31 May 1971 are discussed. The continuum emission observed during the upward acceleration of the surge is attributed to the scattering of photospheric radiation by free electrons. The observed scattered light intensity amounts to a few times 10–5 that of the central disk intensity leading to a column density of n
e
L1020 cm–2. The actual electron density when taking into account the presence of inhomogeneities is n
e
1012 cm–3. The dynamic and morphological behaviour of the surge is considered. 相似文献
17.
In this paper, we have investigated that tilted Bianchi Type I cosmological models for stiff perfect fluid under a supplementary
condition A = B
n
between metric potentials, is not possible. The tilted solution is also not possible when we assume A = t
ℓ, B = t
m
, C = t
n
; ℓ, m and n are constants for ε = p. Thus to preserve tilted nature of model, we assume p = γε, 0 ≤ γ ≤ 1 (barotropic equation of state) for the case A = t
ℓ
B = t
m
and C = t
n
. The physical and geometrical aspects of the models are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
The focussing of gravitational radiation by the interior and exterior gravitational field of a Newtonian gravitational lens
is considered. A graphical method for determining the caustic structure of a Newtonian gravitational lens is presented and
the caustic structure of a solar type gravitational lens is discussed. Estimates of the amplitude magnification in the caustic
region indicate that waves with frequencies less than a critical cutoff frequency ω
c
are not amplified significantly. For a lens of massM this cutoff frequency is ω
c
≈(10-1πM)-1; for the Sun ω
c
≈104s-1.
Work supported in part by National Science Foundation Grant PHY78-05368. 相似文献
19.
C. D. Andriesse 《Astrophysics and Space Science》1980,67(2):461-468
Two critical points in an earlier paper on this theory are further discussed. The first is related to the physical average of the stochastic force driving the mass flux. A more accurate estimate has been made of the mean mass loss, viz. 0.40L
3/2(R/M)9/4/G
7/4, where the symbols have their common meaning. The second has to do with the upper limit to the mass loss and is replaced by the postulate of equipartition of thermal power and mechanical power in the photosphere. This equipartition seems to be reached in stars of spectral type earlier than G8. Only for these stars the above mass loss formula is valid. 相似文献
20.
David L. Lambert 《Astronomy and Astrophysics Review》1992,3(3-4):201-256
Summary The review discusses the solar system (meteoritic) abundances and the possible modes of nucleosynthesis of the 30-oddp-nuclei from74Se to196Hg. In addition to a discussion of the abundances for bulk meteorites, isotopic anomalies related to thep-nuclei are discussed; e.g., the Xe-HL associated with the interstellar diamonds and the extinct radionuclides146Sm and92Nb. Various proposed schemes of synthesizingp-nuclei are reviewed. It is noted that the 7-process (i.e., photoerosion) operating in SN Ia (exploding C-O white dwarfs) appears capable of accounting for the relative and absolute abundances of all but one or two of the rarest ofp-nuclei. Synthesis of these latter nuclei is also discussed. 相似文献