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1.
Ther-centroids and Franck-Condon factors for the bands of theA
2 –X
2+ of CP,C
3 –X
3 of SiC, andB
2+ –X
2+ of CO+ molecules have been determined. The Franck-Condon factors are evaluated by the approximate analytical method of Jarmain and Fraser. The absence of the bands in these systems is explained. 相似文献
2.
Huseyin Alkan 《Astrophysics and Space Science》1978,58(2):453-475
In the present paper
n
0
, for occulation and transit eclipses of partial phases, are evaluated numerically by means of the Runge-Kutta methods. Section 2 contains the required differential equations of
n
0
with respect to the modulusX orC, and Section 3 includes the numerical method of the solutions of these differential equations. Theoretical values of
0
0
and
1
0
, with corresponding values ofC, are also added in this section. 相似文献
3.
A scanning spectropolarimeter has been constructed and used in a preliminary search for conspicuous features of the interstellar polarization curve between
–1 = 1.58
–1 and 2.50
–1. The instrument was used at thef/4.5 prime focus of the 36 telescope of the Cambridge University Observatories. Scans were made on HD2905, HD21389, And and Tau with slitwidths of 50 Å and 100 Å.The commonly adopted method of correcting for instrumental polarisation by using observations of unpolarized stars has been applied. The normalized polarization curves corrected for instrumental polarization for HD2905 and HD21389 reveal a feature near
–1 = 1.68
–1 which is most probably of insterstellar rather than instrumental origin. 相似文献
4.
The Franck-Condon factors and r-centroids, which are very closelyrelated to relative vibrational transition probabilities, have beenevaluated by the more reliable numerical integration procedure forthe bands of c
1 - a
1 and f
1 - a
1 systems of CN
+ and C
2 +
u- X
2 +
g and D
2 g- A
2 u systems of N
+
2 molecular ions of astrophysical interest,using a suitable potential. 相似文献
5.
Vibrational transition probabilities: namely, Franck-Condon factors andr-centroids, have been evaluated using an approximate analytical method for theB-A system of MgO. Morse potential energy curves forB
1+ andA
1 states of MgO have been constructed by use of the latest spectroscopic data. The value ofr-centroids for the band have been found to decrease linearly with the corresponding wavelength. We show results for six new bands in the umbral spectrum of the Sun. 相似文献
6.
The equation of transfer for interlocked multiplets has been solved exactly by the method used by Busbridge and Stibbs (1954) for exponential form of the Planck functionB
v
(T)=b
0+b
1
e
–. 相似文献
7.
N. N. Morozhenko 《Solar physics》1984,92(1-2):153-160
The paper deals with the excitation of the helium singlet level 21
P in the homogeneous and filamentary models of quiescent prominences with following parameters: the optical thickness at the limit of helium Lyman continuum
1c
M
= 0.1–100, T
e
= 7000 K, n
e
= 5 × 1010 cm–3. Assuming a model He atom with seven discrete levels (11
S, 23
S, 21
S, 23
P, 21
P, 33
D, 31
D) and the continuum the steady state equations for the levels 23
S, 21
P and the continuum have been solved together with the radiative transfer equations for the line 584 Å and the continuum 504 Å. The variations with depth of the functions n
2
3
S
/n
1
1
S
(1
c), n
2
1
P
/n
1
1
S
(1c
), and n
+
He
n
e
/n
1
1
S(1c
) as well as the intensities of the triplet (D3, 10830 Å) and singlet (16678, 20581 Å) lines have been calculated. Comparison with observations leads to the following conclusions: (1) The line intensities calculated for filamentary models of prominences agree better with observations than those for homogeneous ones. (2) The helium level 21
P is excited by diffuse field 584 Å being formed by recombinations and spontaneous transitions 21
P – 11
S and escaping from the prominence into the space between the filaments and to the surface. (3) Underpopulation of the singlet level 21
P may be explained by combination of weak excitation mechanism (recombinations and formation of the diffuse field 584 Å) and strong deexcitation mechanism (spontaneous transitions into the level 11
S). 相似文献
8.
Generation of acoustic and gravity waves by turbulence in an isothermal stratified atmosphere 总被引：1，自引：0，他引：1
Robert F. Stein 《Solar physics》1967,2(4):385-432
Lighthill's method of calculating the aerodynamic emission of sound waves in a homogeneous atmosphere is extended to calculate the acoustic and gravity-wave emission by turbulent motions in a stratified atmosphere. The acoustic power output is P
ac 103
o
u
o
3
/l
o
M
5 ergs/cm3 sec, and the upward gravity wave flux is F
zgr 102
o
U
o
3
/l
o (l
o ergs/cm3 sec. Here u
0 is the turbulence velocity scale, l
0 is its length scale, and H the scale height at the atmosphere. M = u
0/c
0 is the Mach number of the turbulence. The acoustic power output is proportional to the maximum value of the turbulence spectrum, and inversely to its rate of falloff at high frequencies. The stratification cuts off the acoustic emission at low Mach numbers. The gravity emission occurs near the critical angle to the vertical
c = cos–1
/
2, where
2
2
= ( - 1)/
2 (c
0/H), and at very short wavelengths. It is proportional to the large wave number tail of the turbulence spectrum. On the sun, gravity-wave emission is much more efficient than acoustic, but can occur only from turbulent motions in stable regions, whereas acoustic waves are produced by turbulence in the convection zone. 相似文献
9.
Intensity, polarization, and cooling rate of the two-photon annihilation radiation are studied in detail in the case of one-dimensional power-law distributions of electrons and positrons, assuming that they occupy the ground Landau level in a strong magnetic fieldB1010–1012 G. Simple analytical expressions for limiting cases are obtained and results of numerical calculations of radiation characteristics are presented. Power-lawe
± distributions
±
±
–k
are shown to generate power-law spectra of the annihilation radiation atEmc
2 andEmc
2, with indices depending on the direction of radiation. The annihilation spectra at =0 show the largest blue-shifts of their maxima and the hardest high-energy tailsI(Emc
2, =0)E
–(k–1). The blue-shifts reduce, and the hard tials steepen, with increasing . At >(2mc
2/E)1/2 the slopes of the high-energy tails rapidly transform to that at =2,I(Emc
2, =/2)E
–(2k+3). The direction-integrated spectraS(E) also display the power-law tials at low and high energies,S(Emc
2)E
–(k+1). The total annihilation rate and energy losses decrease with decreasingk, being higher than for the isotropice
± power-law distributions at the samek. The radiation is linearly polarized in the plane formed by the magnetic field and wave-vector. The polarization degreeP is maximum atEmc
2:P
max0.6 for =/2. Annihilation features and power-law-like hard tails observed in many gamma-ray burst spectra may be associated with the annihilation radiation of the magnetized power-law distributed plasma near neutron stars. Comparison of the observed and theoretical spectra allows one to estimate the power-law index of thee
–
e
+-distribution and the gravitational redshift factor in the radiating region. 相似文献
10.
Mohamed Adel Sharaf 《Astrophysics and Space Science》1987,129(1):19-38
In this paper of the series, the third step of the author's regularization approach will be started by establishing the expansions of the functionX
n
(r)
(, ,u) in terms of the sectorial variables
j
(i)
introduced in Paper IV (Sharaf, 1982) to regularize the highly-oscillating perturbation force of some orbital systems. The literal analytical expressions for the Fourier expansion of the function will be explored in terms of
j
(i)
for anyn positive integer,r any real number whatever the types and the number of sectors forming the divisions situation of the elliptic orbits may be. The basic computational materials of the theory will also be given and for which the method of solution, the recurrence formulae, and the general computational sequence for the coefficients are considered. 相似文献
11.
Jean Meffroy 《Earth, Moon, and Planets》1980,23(1):73-97
Using a method previously applied to the treatment of the Mathieu differential equation, we solve the Hill's differential equation of lunar theory through the way of operational calculus, which avoids the cumbersome infinite determinants of the classical procedure. The one-sided Laplace transformation changes it into a difference equation with an infinite number of terms and variable coefficients. When its first member is divided by a suitable factor, this difference equation is the image of an integral equation of the Volterra type which is equivalent to the initial Hill's differential equation. Solution of this Volterra integral equation is unique and it is the general solution of the Hill's differential equation. This solution is a series in the powers of a small dimensionless parameter
2 which appears as a factor in the second member of the Hill's differential equation. We reduce it to the sum of its terms of degree 12 with respect to which is the precision usually required in a lunar theory and we write down effectively the coefficients of the terms in
2, (
2)2 and the coefficient of the term in (
2)3 which depends upon the initial valuey(0) of the Hill's differential equation. 相似文献
12.
Markandey Singh 《Astrophysics and Space Science》1987,138(1):79-86
Vibrational transition probabilities namely Franck-Condon factors and
-centroids have been evaluated using an approximate analytical method for theA-X systems of OH and PN. KKRV potential energy curves forX
2
i
,X
1+,A
2+, andA
1 states of OH and PN have been constructed using the latest spectroscopic data. The value of
-centroids for the band have been found to increase linearly with the corresponding wavelengths. We show results for six new bands and OH and eight new bands of PN in the spectra of astronomical objects. 相似文献
13.
M. T. Edalati 《Astrophysics and Space Science》1978,58(1):3-19
A new method has been developed by Kopal (1977c, Paper XII) to make use of expressions for the fractional loss of light
0
l
of the arbitrarily limb-darkened stars in the form of Hankel transforms of zero-order, in order to evaluate the explicit forms of the
0
l
s for different types of eclipse, as well as of the momentsA
2m of the respective light curves in a closed form. The automated method has been tested successfully on the light curves of RT Persei. Also, a photometric curve fit of RT Persei is investigated by application of numerical quadratures to determine the theoretical light curve appropriate for the Roche model. Finally a comparative discussion is given of various methods of light curve analaysis.On leave from Department of Physics, University of Ferdowsi, Mashad, Iran. 相似文献
14.
Morse potential energy curves forC
1+ andC
1+ of AlH have been constructed. The energy values have been found to increase from vibrational levels 0 to 6 and decrease from vibrational levels 7 to 50 with the corresponding centre and half-width in the stateC
1+. InC
1+ state the energy values have been found to increase from vibrational levels 0 to 28 and decrease from vibrational levels 29 to 50 with the corresponding centre and half-width. 相似文献
15.
P. R. Amnuel O. H. Guseinov H. I. Novruzova Yu. S. Rustamov 《Astrophysics and Space Science》1984,107(1):19-50
On the basis of empirical (D)-dependency at the frequency of 5 GHz constructed using 15 planetary nebulae with the independently measured distances (10–171×10–20 W m–2 Hz–1 ster–1), we evaluated distances of 335 objects. Independent evidence of the correctness of the accepted scale are given. Then(D)-dependency is constructed and it is shown that atD<0.08 pc the mean electron density is higher than the one determined by the Seaton method. We showed that the filling factor diminishes with the increase of the PN diameter (1 atD0.08 pc and 0.2 atD0.4 pc). the ionized mass of 33 PNs is determined. With the diameter increase the ionized mass grows and atD0.4 pc reaches the valueM0.07M
. We used the new distance scale when investigating the space distribution of PNs. The mean scale height =130±15 pc and the mean gradient of the change of surface densitym=0.37, which allowed us to estimate the total number of nebulae in the GalaxyN4×104. We divided the PNs according to their velocities (withV
LSR>35 km s–1 andV
LSR<35 km s–1) and permitted us to confirm that the PN belong to different sub-systems of the Galaxy. The estimated local formation rate of PNs [=(4.6±2.2)×10–12 pc–3 yr–1] is a little higher than the one of the white dwarfs. That can be explained by a large number of PNs having binary cores, which used in our sample. The statistical estimation of PN expansion velocity showed thatV
ex increases from 5–7 km s–1 (atD0.03 pc) to 40–50 km s–1 (atD0.8 pc). 相似文献
16.
In this paper we adopt the method of relativistic fluid dynamics to examine the number density distribution of stars around a massive black hole in the core of stellar clusters. We obtain extensive results,n(r) r
–a, 3/2a9/2, which include, respectively, then(r) r
–7/4 power law obtained by Bahcall and Wolf and then(r) r
–9/4 power law by Peebles. Sincen(r) is not an observable quantity for star clusters, we also consider general relativity effects, i.e., the consequence of the bending of light, in calculating the projected density of stars in such a system. As an example we employ a massive black hole 103
M
inlaid in the center of a globular cluster and calculate various projected densities of stars. The results show that cusp construction occurs in all cases unless the central black hole massM=0, and the polytropic index does not affect at all the position of the capture radiusr
a. The obvious differences in the surface density is only embodied in the interior of the capture radius. At the outer regions of the core, the surface density of stars declines rapidly with ar
–5 power law in all cases. These results can be applied to cases of unequal-mass and non-steady state. 相似文献
17.
An exact analysis of the effects of mass transfer on the flow of a viscous incompressible fluid past an uniformly accelerated vertical porous and non-porous plate has been presented on taking into account the free convection currents. The results are discussed with the effects of the Grashof number Gr, the modified Grashof number Sc, the Schmidt number Sc, and the suction parametera for Pr (the Prandtl number)=0.71 representating air at 20°C.Nomenclature
a
suction parameter
-
C
species concentration
-
C
species concentration at the free stream
-
g
acceleration due gravity
- Gc
modified Grashof number (vg*(C
–C
)/U
0
3
)
- Pr
Prandtl number (C
p/K)
-
T
temperature of the fluid near the plate
-
T
dimensionless temperature near the plate ((T-T
)/(T
-T
))
-
U(t)
dimensionless velocity of the plate (U/U
0)
-
v
normal velocity component
-
v
0
suction/injection velocity
-
x, y
coordinate along and normal to the plate
-
v
kinematic viscosity (/gr)
-
C
p
specific heat at constant pressure
-
C
w
species concentration at the plate
-
C
non-dimensional species concentration ((C-C
)/(C
w
-C
))
- Gr
Grashof number (g(T
w
-T
)/U
0
3
)
-
D
chemical molecular diffusivity
- K
thermal conductivity
- Sc
Schmidt number (/D)
-
T
w
temperature of the plate
-
T
free stream temperature
-
t
time variable
-
t
dimensionless time (tU
0
2
/)
-
U
0
reference velocity
-
u
velocity of the fluid near the plate
-
u
non-dimensional velocity (u/U
0)
-
v
dimensionless velocity (v/U
0)
-
v
0
non-dimensionalv
0
(v
0
/U0)=–at–1/2
-
y
dimensionless ordinate (yU
0/)
-
density of the fluid
-
coefficient of viscosity 相似文献
18.
G. A. Gurzadyan 《Astrophysics and Space Science》1979,64(1):25-43
As a result of the analysis of the observed interstellar 2800 Mgii absorption line data, an empirical relationship — a positive correlation — between the equivalent widthW(2800) and the effective temperature of the starT was discovered (Figure 1). However, in the case when this doublet is of stellar (photospheric) origin, only a negative correlation betweenW(2800) andT exists. Hence, the existence itself of such a positive correlation betweenW(2800) andT may be viewed as incomprehensible for the present influence of the star on the strength of the absorption line 2800 Mgii of nonstellar origin.On the other hand, we have evidence that the ionizing radiation of hot stars cannot provide for the observed very high degree of ionization of the interstellar magnesium. In particular, the observations give for interstellar magnesium the ratioN
+/N
1 1000, while in the case of ionization under the action of stellar radiation only we haveN
+/N
1 10.The assumption that circumstellar clouds surround hot stars can naturally explain these and other similar facts. A method for the determination of the general parameters-size, concentration, mass etc. — of the circumstellar clouds is developed. The main results of the application of this method to the relation of more than 20 hot stars are:(1) The circumstellar clouds surround almost (70%) all hot giants and subgiants. In the remaining (30%) cases, the absence of circumstellar envelopes requires additional evidence. (2) The linear sizes of circumstellar clouds vary within wide ranges — from 0.002 pc up to 1 pc. Most frequent are clouds with size of 0.1 pc. (3) The main concentration of hydrogen atoms (electrons) in circumstellar clouds is of the order of 100 cm–3; the minimum value is 20–30 cm–3, the maximum 104 cm–3. In one case (Deneb) the electron concentration rises up to 105 cm–3 for the size of the cloud 0.001 pc=3×1015 cm. (4) Stars of the same spectral and luminosity classes may possess circumstellar clouds characterized by quite different parameters. (5) Hydrogen in circumstellar clouds is completely ionized; for these clouds the optical depth
c
1; on the average,T
c 0.005. (6) The integrated brightness of circumstellar clouds is substantially fainter (by 8–10m) than that of the central star. This is the reason why these clouds cannot be detected by ground-based observations. (7) The masses of individual circumstellar clouds vary from 1 down to 10–4 . This gives for the mass ejection rate from 10–10 to 10–6 per year in case if these clouds are formed by the braking and accumulation of the ejected mass.The method of 2800 Mgii seems very convenient, fruitful and promising for the detection and study of circumstellar envelopes. Also, this method is very sensitive for a determination of the general parameters of such clouds, and concerns practically all their geometric, physical, kinematic and other properties. 相似文献
19.
This paper is devoted to Force-Free Electromagnetic Oscillations in a constant magnetic field. A correction is made in the derivation of the basic equation. The paper confirms the predicted spectrum of frequencies, namely
n
=
o
(n + 1)1/2;n = 0, 1, 2, .... In addition it is suggested that hybrid frequency
n
= (
n
2
+
H
2
)1/2 should be found in observational data. 相似文献
20.
J. Seimenis 《Astrophysics and Space Science》1990,170(1-2):205-208
We develop a new method to find solutions of the equations of motion in Hamiltonian Dynamical Systems. The idea of the method is to express the solution of the nonlinear ODE in the formx=N/D
n
, whereN andD are Fourier series andn is an appropriate constant. We apply this method to a galactic potential with three degrees of freedom.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献