共查询到20条相似文献，搜索用时 31 毫秒
1.
Boris Garfinkel 《Celestial Mechanics and Dynamical Astronomy》1983,30(4):373-383
In a previous publication (1977) the author has constructed a family () of long-periodic orbits in the Trojan case of the restricted problems of three bodies. Here he constructs the domain of the analytical solution of the problem of the motion, excluding the vicinity of thecritical divisor which vanishes at the exact commensurability of the natural frequencies 1 and 2. In terms of thecritical masses mj(2), or the associatedcritical energies
j
2
(m), is the intersection of the intervals ofshallow resonance, of the form. Inasmuch as the intervals |2–
j
2
|<j ofdeep resonance aredisjoint, it follows that (1) the disjointed family () embraces the tadpole branch, 021, lying in: and (2) despite the clustering of
j
2
(m) atj=, the family () includes, for 2=1, an asymptoticseparatrix that terminates the branch in the vicinity of the Lagrangian pointL
3.In a similar manner, the family () can be extended to the horseshoe branch 1<2
2
2
. 相似文献
2.
R. V. Isakov A. A. Ruzmaikin D. D. Sokoloff M. V. Faminskaya 《Astrophysics and Space Science》1981,80(1):145-155
The asymptotic properties of a turbulent disk dynamo at large dimensionless numbersR
andR
characterizing the helicity and the differential rotation are analysed. Three types of generations in the dependence of the relations betweenR
andR
are found: 2-dynamo and two types of -dynamo. For each of these types the rates of growth are obtained and the forms of solution are pointed out. Boundaries of the disk dynamo approximation are given. 相似文献
3.
In the present paper, H-evolutive curves of chromospheric events are compared with flux evolutive curves of X-ray events observed at the same time in different spectral regions. A correspondence between the emissions E(I
H/I
chr)'s at higher and higher H-intensity levels, and the X-ray fluxes F()'s in harder and harder -ranges is shown. Further, the present observations seem to indicate the existence of a single triggering mechanism during the flash-phase of a flare. It is also shown that these results may be in agreement with Brown's model for chromospheric flares. 相似文献
4.
Ultraviolet spectra of CMi and Cen A taken with moderate spectral resolution (approx. 1.8 Å) are used to analyse whether a determination of stellar chemical abundances of Fe and Cr and of the photospheric parameters is possible. For CMi, for which good spectral data are available, we findT
eff=7660±110 K; logg
eff=3.05±0.1. Further, log(Fe)=–0.06±0.09; log (Cr)=–0.01±0.09 with regard to standard (solar) abundances. For Cen A the resulting data — particularly the photospheric ones — are less certain, but it seems that the Fe abundance may be smaller than the standard value. 相似文献
5.
We consider the effect that coherent motion has on the observed brightness of moving clouds above the photosphere. We find that steady state clouds (constant N
e
and T
e
) that are moving perpendicular to the line of sight will appear brighter in H for speeds between 8 and 100 km/sec and dimmer for speeds greater than 135 km/sec. The brightening and dimming are due to apparent Doppler shifts of the respective H absorption and the Lyman- emission profiles seen by the absorption profile of the moving cloud.We apply this analysis, along with optical depth and geometrical considerations, to the observed brightness variations of the 1 March 1969 limb eruptive prominence. We find that all of the observed brightening and dimming can be explained by the motions, and that no significant change in the prominence N
e
or T
e
was necessary during the observed H event. This conclusion is significant in interpreting an X-ray burst that began as the prominence velocity increased abruptly at the time of maximum H intensity. The thermal X-ray peak occurred 150 sec later when the prominence had become faint again. There was no associated flare that was visible in H. We discuss the relative brightness of H and D
3 in a specific moving prominence knot.We note that the observed range of limb speeds (30–150 km/sec) may be due to the combined H Doppler brightening and Lyman- dimming effects. We also discuss generally the H brightness of disk surges (bright and dark) and flares, and sprays and puffs that occur at or near the limb.Now at the Dept. of Physics and Astrophysics, University of Colorado, and High Altitude Observatory (NCAR) Boulder, Colo., U.S.A. 相似文献
6.
V.T. Doroshenko K.K. Chuvaev S.G. Sergeev V.I. Pronik Yu.F. Malkov 《Astrophysics and Space Science》1997,252(1-2):85-94
In the time period from 1972-1993, the Seyfert 1 galaxy Mrk 509 showed large variations of its optical continuum and broad emission line fluxes. The broad H and H emission lines have approximately the same profiles, which retain their shape during flux variations. The relationship between the continuum and emission line fluxes varies with time. The spectral energy distribution of the variable continuum based on UBVRI data has the form lgF() lg, with the dereddened = -0.60. 相似文献
7.
A. O. Allakhverdiyev A. I. Asvarov O. H. Guseinov F. K. Kasumov 《Astrophysics and Space Science》1986,123(2):237-258
The possibility of realization of a mechanism of regular acceleration of charged particles at the shock front in shell-type supernova remnants (SNR) is demonstrated. In the framework of this mechanism, in order to satisfy the observed fact that there is no separation of SNR emissivity by spectral indices , it is necessary that the value e
e
(where e is the fraction of particles injected into the mechanism and e is the threshold energy of injection) should be a strongly increasing function of . The shape of this function is obtained by using calibration objects with independently estimated magnetic fields, and its behaviour with respect to the evolution of SNRs is investigated.The magnetic field values estimated for the chosen SNRs with the aid of this function are close to their minimum values if one ignores the proton component of relativistic particles. The ratio of magnetic field energy density to the kinetic energy density increases with the increase of the SNR diameter. 相似文献
8.
In this paper independent evidence in favour of the hypothesis proposed by Thakur and Sapre (1979) that a QSO consists of a bright central object embedded in an extended nebulosity has been presented.
U–B
and
B–V
, the spectral indices in (U-B) and (B-V) colours, have been calculated for a sample of 80 QSOs with redshiftz0.76. In Figure 1 = (
B–V
–
U–V
) has been plotted against = (
B–V
+
U–B
)/2. In this figure the QSOs in which detectability of neubulosities has been predicted by Thakur and Sapre (1979) occupy a separate but adjacent part of the diagram as compared to those for which such a prediction has not been made. In Figure 2 (U-B)0 has been plotted against (B-V)0 for the same sample of 80 QSOs, where (U-B)0 and (B-V)0 are the (U-B) and (B-V) colours corrected for galactic extinction. In this plot also, a similar separation of the two classes of objects is discernible. Another empirical criterion—namely, (B-V)00.32 for the detectability of nebulosities around QSOs—has been suggested. 相似文献
9.
G. Contopoulos 《Celestial Mechanics and Dynamical Astronomy》1986,38(1):1-22
We study the bifurcations of families of double and quadruple period orbits in a simple Hamiltonian system of three degrees of freedom. The bifurcations are either simple or double, depending on whether a stability curve crosses or is tangent to the axis b=–2. We have also generation of a new family whenever a given family has a maximum or minimum or .The double period families bifurcate from simple families of periodic orbits. We construct existence diagrams to show where any given family exists in the control space (, ) and where it is stable (S), simply unstable (U), doubly unstable (DU), or complex unstable (), We construct also stability diagrams that give the stability parameters b1 and b2 as functions of (for constant ), or of (for constant ).The quadruple period orbits are generated either from double period orbits, or directly from simple period orbits (at double bifurcations). We derive several rules about the various types of bifurcations. The most important phenomenon is the collision of bifurcations. At any such collision of bifurcations the interconnections between the various families change and the general character of the dynamical system changes. 相似文献
10.
Oddbjørn Engvold 《Solar physics》1978,56(1):87-106
High spatial resolution spectral observations of five hedgerow prominences were made in H, He i D3 and Ca ii H and K.The observed relations between the lines were not the same in all prominences. The Ca ii H and K lines were 2–4 times brighter relative to H and D3 than predicted theoretically. The optical thickness of H was less than for the H and K lines, the H was optically thin in medium faint prominence structures. Faint structures appeared slightly hotter than bright structures.On leave from Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, Oslo 3, Norway. 相似文献
11.
This investigation is the second of two centering on the parameter =(×Bh)z/Bz=0Jz/Bzand its derivation from photospheric vector magnetogram data. While can be evaluated at every spatial position where the vector B is measured, for many reasons it is useful to determine a single value of to parameterize the magnetic complexity of an entire active region, here called AR(see Leka and Skumanich, 1999). As such, the limitations in today's vector magnetograph data, e.g., finite spatial resolution and limited field of view, may influence any final 'AR' value. We apply three methods of calculating 'AR' to degraded high-spatial-resolution data and find that in general the discrepancies worsen for decreasing resolution compared to the original. We apply the three methods to sub-regions centered on the constituent sunspots for AR 7815. Two of the sub-regions are shown to have magnetic twist with significant magnitude but opposite sign. We show by mosaicing or otherwise combining separate sunspot observations that a measure of ARcan be calculated which is consistent with a single large field-of-view observation. Still, the AR0 assigned for the entire active region is an average, and does not accurately represent the magnetic morphology of this flux system. To measure the validity of the ARparameterization, we demonstrate that, from each method, a relevant quantity can be calculated which describes the 'goodness of fit' of the resulting AR. Given the spatial variation of (x,y) over an active region, it is suggested that such a second parameter be used either to indicate uncertainty in ARor as a criterion for data selection, as appropriate. 相似文献
12.
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
13.
Jan-Cees Van Der Meer 《Celestial Mechanics and Dynamical Astronomy》1982,27(2):131-149
Consider a Hamiltonian system of two degrees of freedom at an equilibrium. Suppose that the linearized vectorfield has eigenvaluesi,i,–i,–i ( , >0) and is not semisimple. In this paper we discuss the real normalization of the Hamiltonian function of such a system. We normalize the Hamiltonian up to 4th order and show how to compute its coefficients. For the planar restricted three body problem atL
4 the coefficient that plays an important role in the investigation of the qualitative behaviour of periodic solutions near the equilibrium is explicitly calculated. 相似文献
14.
V. F. Litvin F. M. Holzmann B. S. Taibin A. V. Smirnov E. T. Grebenkina V. N. Baryshnikov V. V. Orlov J. P. Anosova G. D. Polyakova 《Astrophysics and Space Science》1994,215(2):245-261
The diagramV - log(1 +z
e
) as function of (, ) is considered for the quasars. HereV is the apparent visual magnitude,z
e
is the emission line redshift, and are the equatorial coordinates. Two opposite extreme spots NE and SE are observed on the sky, where the inclination of the straight line fitting the dependenceV - log(1 +z
e
) is maximum and minimum. The coordinates of the centres of these extreme spots are (
NE,
NE) = (282°, +42°) and (
SE,
SE) = (70°, -38°) with errors 5°. A hypothesis of the Superattractor (SA) is proposed to explain such an effect. Two independent tests of this hypothesis are realized. First, the dependence or the frequency a of the absorbers in QSO spectra on (, ) is investigated. A region of the larger a is found. The coordinates of its centre are (, ) = (82°, - 10°) with error 5°. Second, the cases ofz
a
>z
e
are plotted in the Mercatorial projection (, ). The most of the casesz
-z
e
> 0.02 are concentrated within the circle with radiusR = 34° and centre (, ) = (50°, - 15°). The both anomalous regions overlap the Southern extreme spot around SE. The SA direction is (, ) = (67°, -21°) with errors about 12°. The redshift of SA isz
SA = 1.7 ± 0.3 that corresponds to the distancer
SA = (3100 ± 300)h
–1 Mpc for the Hubble constantH
0 = 75h kms–1 Mpc–1. The SA mass isM
SA ~ 1018-1020
M
. The orientation of the normal to the quasiperiodical large-scale sheet structure on the sky occurs near SA. 相似文献
15.
The problem of single Compton scattering is considered and the resulting spectrum, angular distribution and polarization of scattered photons in a general case are obtained. The inverse Compton scattering (ICS) for arbitrary energies of electronsE and photons 0 is investigated in detail. In the case of isotropically-distributed initial photons and relativistic electrons, a strong rise of the scattered spectrum near the upper edge takes place, starting from the values of the characteristic parameterb4E
010 (in units of mc2=1). The energy-loss rate of relativistic electrons due to ICS is calculated. It is shown that the relativistic electrons of the energiesE100 MeV, when scattering on the X-rays with 0~10KeV, transmit the dominant part of their energy to the photons which fall after scattering into the energy range of the electrons (100 MeV).The radiation spectrum of ICS, as well as the energy-losses of relativistic electrons distributed by power-lawE
–, are calculated. The radiation spectrum reveals the power-law behaviour with the different indices in two limits: the dependence –(1)/2 at 01 gradually changes to –(+1) ln (0) law for 01. 相似文献
16.
The thermal contrast , and the umbra-penumbraA
u/A
p, were calculated for 63 sunspots of various sizes and morphologies. Contrary to the assumptions of the PSI model, andA
u/A
p were found to be quite variable. The values of ranged from 0.1807 to 0.4266;A
u/A
p ranged from 0.0089 to 0.4899. The values of andA
u/A
p correlated well (r = 0.6018;p<0.005) and the regression for andA
u/A
p was obtained: = (0.220 ± 0.016) + (0.340 ± O.06)A
u/A
p. The values of andA
u/A
p were then compared with complexity ratings, magnetic field strength, time, and . The quantities andA
u/A
p were found to be independent of the complexity, magnetic field strength, and time factors. The correlation between andA
u/A
p lead to the proposed division of into an umbral thermal contrast u, and a penumbral thermal contrast p. These values were calculated from the photometric data: u = 0.57 ± 0.01 and p = 0.26 ± 0.006. 相似文献
17.
The H observations of a selected sample of bright Be stars are presented. The available infrared observations at K band (2.2 m) of these stars have been used to find the infrared excess emission. The analysis of the combined data show thatL
H, the luminosity of the H emission line, is proportional toL
IR, the luminosity of the infrared excess emission. The linear correlation betweenL
IR andL
H shows that both the infrared excess and the H line originate in a common region. It is also detected that the infrared excess emission is produced throughout the whole envelope whereas the H is emitted in some defined region of the circumstellar (CS) envelope. 相似文献
18.
We analyze a time series of high resolution observations near the solar limb, obtained in H and the Mg b1 line. We identified arch-shaped dark mottles, which are thin, faint H structures observable under very good seeing conditions, best seen in H +0.75 Å. Their mean length is about 15, their mean height about 6 and indicative lifetimes is of the order of 5 min. They show negative (away from the observer) line-of-sight velocities. A possible interpretation is that material flows from the apex towards the feet of the arches. 相似文献
19.
The reciprocal influence of the electrons and protons, on one side, and the -particles, on the other side in the quiet solar wind is investigated within the framework of a conductive three-fluid model (with frictional forces included). For this purpose two mathematical methods are used, namely: I. Simultaneous solution of the fluid equations for all three species; and II. Solution of two-fluid equations (for electrons and protons) followed by that of a modified one-fluid equation for the -particles (in which the two-fluid solutions are used for electrons and protons).The results of our investigation indicate the following: (a)The macroscopic -particle characteristics as obtained from the two methods of solution are almost identical. Thus, the differences between the three-fluid and two-fluid characteristics of the electrons and protons represent a second order (and negligible) effect on the -particle characteristics. In both approaches, the frictional interaction between -particles and protons raises the (lower) -particle streaming velocity to that of the protons and decreases the relative to proton density ratio to a value about 0.035, as observed at 1 AU, (b)The electron and proton characteristics obtained from three-fluid and two-fluid solutions are similar, except for the proton temperature. The two-fluid solution providesT
p-values which, though within the observational error, are larger than those obtained from the simultaneous three-fluid solution (at 1 AU, the difference amounts to about 30%). Thus, the -particles affect the temperature profile of the protons in the solar wind through heat exchange (mainly), dynamical friction, as well as through their contribution to the interplanetary electrostatic field. 相似文献
20.
We report on a prominence eruption as seen in H with the Crimean Lyot coronagraph, the global H network, and coronal images from the LASCO C2 instrument on board SOHO. We observed an H eruption at the northwest solar limb between 07:38:50 UT and 07:58:29 UT on 11 August 2000. The eruption originated in a quiet-Sun region and was not associated with an H filament. No flare was associated with the eruption, which may indicate that, in this case, a flux rope was formed prior to the eruption of the magnetic field. The H images and an H Dopplergram show a helical structure present in the erupted magnetic field. We suggest that the driving mechanism of the eruption may be magnetic flux emergence or magnetic flux injection. The limb H observations provide missing data on CME speed and acceleration in the lower corona. Our data show that the prominence accelerated impulsively at 5.5 km s–2 and reached a speed slightly greater than 800 km s–1 in a narrow region (h<0.14 R
) above the solar surface. The observations presented here also imply that, based only on a CME's speed and acceleration, it cannot be determined whether a CME is the result of a flare or an eruptive prominence. 相似文献