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1.
In this paper we review the drift theory of charged particles in electric and magnetic fields. No new physical interpretations are added to this classical topic, but through an alternative, simplified derivation of the guiding centre velocity, several complexities are eliminated and possible misconceptions of the theory are clarified. It is shown that:
  1. The curvature/gradient drift velocity in the magnetic field, averaged over a particle distribution function is to lowest order in the direction of?×B/B 2, while the average particle velocity is in the direction ofB×? P withP the scalar particle pressure.
  2. These drift directions are correct for first-order expansions of the particle distribution function, and only second-order or higher expansions change these directions.
  3. The?×B/B 2 drift, which is the standard gradient plus curvature drift, and which is usually considered as a ‘single particle’ drift, need not be ‘reconciled’ with theB×? P, or ‘macroscopic, collective’ drift, as is often asserted in the literature. They are in fact related per definition and we show how.
  4. When viewed in fixed momentum intervals (p,p+dp), the so-called Compton-Getting factor enters into the electric field (E×B)/B 2 drift term.
  5. The results are independent of the scale length of variation ofE andB, in contrast to existing drift theory. We discuss the implications of this result for three important cases.
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2.
We examine the propagation of Alfvén waves in the solar atmosphere. The principal theoretical virtues of this work are: (i) The full wave equation is solved without recourse to the small-wavelength eikonal approximation (ii) The background solar atmosphere is realistic, consisting of an HSRA/VAL representation of the photosphere and chromosphere, a 200 km thick transition region, a model for the upper transition region below a coronal hole (provided by R. Munro), and the Munro-Jackson model of a polar coronal hole. The principal results are:
  1. If the wave source is taken to be near the top of the convection zone, where n H = 5.2 × 1016 cm?3, and if B = 10.5 G, then the wave Poynting flux exhibits a series of strong resonant peaks at periods downwards from 1.6 hr. The resonant frequencies are in the ratios of the zeroes of J 0, but depend on B , and on the density and scale height at the wave source. The longest period peaks may be the most important, because they are nearest to the supergranular periods and to the observed periods near 1 AU, and because they are the broadest in frequency.
  2. The Poynting flux in the resonant peaks can be large enough, i.e. P ≈ 104–105 erg cm?2s?1, to strongly affect the solar wind.
  3. ¦δv¦ and ¦δB¦ also display resonant peaks.
  4. In the chromosphere and low corona, ¦δv ≈ 7–25 kms?1 and ¦δB¦ ≈0.3–1.0 G if P ≈104-105 erg cm?2s?1.
  5. The dependences of ¦δv¦ and ¦δB¦ on height are reduced by finite wavelength effects, except near the wave source where they are enhanced.
  6. Near the base, ¦δB¦ ≈ 350–1200 G if P ~- 104–105. This means that nonlinear effects may be important, and that some density and vertical velocity fluctuations may be associated with the Alfvén waves.
  7. Below the low corona most wave energy is kinetic, except near the base where it becomes mostly magnetic at the resonances.
  8. ?0 < δv 2 > v A or < δB 2 > v A/4π are not good estimators of the energy flux.
  9. The Alfvén wave pressure tensor will be important in the transition region only if the magnetic field diverges rapidly. But the Alfvén wave pressure can be important in the coronal hole.
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3.
The Weinberg relation (which connects the Hubble constantH to the mass of a typical elementary particle) is an empirical relation hitherto unexplained. I suggest an explanation based on the Zel'dovich energy tensor of vacuum in a Robertson-Walker universe with constant deceleration parameter,q = const. This model leads to
  1. the Weinberg relation,
  2. a varying cosmological term Λ scaling asH 2,
  3. a varying gravitational constantG scaling asH,
  4. a matter creation process throughout the universe at the rate 10?47 g s?1 cm3,
  5. a deceleration parameter in the range -1 to 1/2, which allows a horizon-free universe and makes the lawG/H = constant, consistent with the Viking lander data on the orbit of planet Mars.
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4.
  1. The exotic system H 3 ++ (which does not exist without magnetic field) exists in strong magnetic fields:
    1. In triangular configuration for B≈108–1011?G (under specific external conditions)
    2. In linear configuration for B>1010?G
  2. In the linear configuration the positive z-parity states 1σ g , 1π u , 1δ g are bound states
  3. In the linear configuration the negative z-parity states 1σ u , 1π g , 1δ u are repulsive states
  4. The H 3 ++ molecular ion is the most bound one-electron system made from protons at B>3×1013?G
Possible application: The H 3 ++ molecular ion may appear as a component of a neutron star atmosphere under a strong surface magnetic field B=1012–1013?G.  相似文献   

5.
J. J. Aly 《Solar physics》1992,138(1):133-162
Some useful properties of a finite energy, constant-α, force-free magnetic field B α occupying a half-space D are presented. In particular:
  1. Fourier and Green representations of B α are obtained and used to derive conditions for the existence and uniqueness of a B α having a given normal component B z on the boundary ?D.
  2. The asymptotic behaviour of B α at infinity as well as stability results against changes in the boundary condition on ?D and in the value of α are established.
  3. The energy of B α is shown to be smaller than the energy of the open field having the same B z on ?D, thus confirming an earlier conjecture (Aly, 1984).
  4. B α is proved to not be a Taylor-Heyvaerts-Priest state, in spite of the fact that its relative helicity H is finite and that it is the only solution of the Lagrange-Euler equation associated with the problem of minimizing the energy among all the fields having the same value of H and the same B z on ?D.
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6.
From a comparative study between stellar and gas data it is seen that turbulent and hydrodynamic motions in the Galaxy are common to both types of materials:
  1. Galactic clusters have sizes and intrinsic dispersions compatible with the modified form of the Kolmogorov law seen in molecular clouds: undimensional velocities σ(km s?1)=0.54d 0.38 (pc). This indicates that ‘typic’ clusters were born from ‘typic’ dark clouds as these of the Lynds's catalogue (diametersd<10 pc, dispersions σ<1.5 km s?1 hydrogen densitiesn H>200 atom cm?3). These clouds have mass enough to form galactic clusters (1000–3000M ).
  2. The cluster formation is related to the supersonic range of the Kolmogorov relationship σ(d>1 pc) while the AFGKM stars are related to the subsonic range of the same relationship σ(d<0.3 pc), the intermediate transition zone is probably related to OB stars and/or trapezia.
  3. The effects of the magnetic fields in the clouds are also discussed. It seems to be that in the clouds the magnetic energy does not exceed the kinetic energy (proportional toσ 2(d)) and that this determinates the freezing criteria. The hypotheses introduced here can be checked with 21 cm Zeeman splitting.
  4. Low-density globular clusters are also coherent with the Kolmogorov relationship. Some hypotheses about their origin and the type of clouds where they were born are discussed. This last part of the study lets open the possibility of further studies about evolution of globular clusters.
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7.
Hot spots similar to those in the radio galaxy Cygnus A can be explained by the strong shock produced by a supersonic but classical jet \(\left( {u_{jet}< c/\sqrt 3 } \right)\) . The high integrated radio luminosity (L?2×1044 erg s?1) and the strength of mean magnetic field (B?2×10?4 G) suggest the hot spots are the downstream flow of a very strong shock which generates the ultrarelativistic electrons of energy ?≥20 MeV. The fully-developed subsonic turbulence amplifies the magnetic field of the jet up to 1.6×10?4 G by the dynamo effect. If we assume that the post-shock pressure is dominated by relativistic particles, the ratio between the magnetic energy density to the energy density in relativistic particles is found to be ?2×10?2, showing that the generally accepted hypothesis of equipartition is not valid for hot spots. The current analysis allows the determination of physical parameters inside hot spots. It is found that:
  1. The velocity of the upstream flow in the frame of reference of the shock isu 1?0.2c. Radio observations indicate that the velocity of separation of hot spots isu sep?0.05c, so that the velocity of the jet isu jet=u 1+u sep?0.25c.
  2. The density of the thermal electrons inside the hot spot isn 2?5×10?3 e ? cm?3 and the mass ejected per year to power the hot spot is ?4M 0yr?1.
  3. The relativistic electron density is less than 20% of the thermal electron density inside the hot spot and the spectrum is a power law which continues to energies as low as 30 MeV.
  4. The energy density of relativistic protons is lower than the energy density of relativistic electrons unlike the situation for cosmic rays in the Galaxy.
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8.
Two-dimensional distributions of kinetic temperature, density and turbulent velocity are obtained for four quiescent prominences observed at the Peruvian eclipse of 12 November, 1966.
  1. The kinetic temperature derived from line widths is around 6000–7000 K in the central part of prominences and rises to 12000K in both edges and possibly in the top of prominences.
  2. The turbulent velocity shows a similar tendency, being 7–9 km/sec in the central part and ≈ 20 km/sec in the outer part. The turbulent velocity also increases slowly towards higher heights in the prominence.
  3. The electron density derived both from the Stark effect and the intensity ratio of the continuous spectra turns out to be about 1010.2–1010.6 cm?3 in the central portion of two prominences.
  4. From the width and the intensity, neutral helium lines are shown to originate in the same region as hydrogen and metallic lines where the kinetic temperature goes down to 6000 K. This indicates that neutral helium is emitted after the ionization due to UV radiation from the corona and the transition region.
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9.
This paper outlines the problems of the quasi-steady matter-antimatter boundary layers discussed in Klein-Alfvén's cosmological theory, and a crude model of the corresponding ambiplasma balance is presented:
  1. At interstellar particle densities, no well-defined boundary layer can exist in presence of neutral gas, nor can such a layer be sustained in an unmagnetized fully ionized ambiplasma.
  2. Within the limits of applicability of the present model, sharply defined boundary layers are under certain conditions found to exist in a magnetized ambiplasma. Thus, at beta values less than unity, a steep pressure drop of the low-energy components of matter and antimatter can be balanced by a magnetic field and the electric currents in the ambiplasma.
  3. The boundary layer thickness is of the order of 2x 0?10/BT 0 1/4 metres, whereB is the magnetic field strength in MKS units andT 0 the characteristic temperature of the low-energy components in the layer.
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10.
Recent gamma-ray observations of solar flares have provided a better means for estimating the heating of the solar atmosphere by energetic protons. Such heating has been suggested as the explanation of the continuum emission of the white-light flare. We have analyzed the effects on the photosphere of high-energy particles capable of producing the intense gamma-ray emission observed in the 1978 July 11 flare. Using a simple energy-balance argument and taking into account hydrogen ionization, we have obtained the following conclusions:
  1. Heating near τ5000 = 1 in the input HSRA model atmosphere is negligible, even for very high fluxes of energetic particles.
  2. Energy deposition increases with height for the inferred proton spectra, and does not depend strongly upon the assumed angle of incidence. The computed energy inputs fall in the range 10–100 ergs (cm3 s)?1 at the top of the photosphere.
  3. H? continuum dominates for column densities as small as 1022 cm?3, but at greater heights hydrogen ionizes sufficiently for the higher continua to dominate the energy balance.
  4. The total energy deposited in the ‘photospheric’ region of H? dominance could be within a factor of 3 of the necessary energy deposition, by comparison with the white-light flare of 1972 August 7, but the emergent spectrum is quite red so that the intensity excess in the visible band is insufficient to explain the observations.
In summary, it remains energetically possible, within observational limits, that high-energy protons could cause sufficient heating of the upper photosphere to produce detectable excess continuum, but emission from the vicinity of τ = 1 is not significant.  相似文献   

11.
The jet/grain model proposed by Ramatyet al. (1984, hereafter abbreviated as RKL) for production of the narrow gamma-ray lines reported from SS433 is examined and shown to be untenable on numerous grounds. Most importantly:
  1. The huge Coulomb collisional losses (W c?2×1041 erg s?1) from the jet, which would necessarily accompany non-thermal production of the gamma rays, demands a jet acceleration/collimation process acting over a very long range and with a power at least 102 times the Eddington limit for any stellar object.
  2. There is a collisional thick target limit (irrespective of jet mass) to the gamma ray yield per interstellar proton. Consequently, the gamma-ray data demand an improbably high interstellar density (?109 cm?3).
  3. For the grains to be kept cool enough (?3000 K) to survive the heating rateW c either by radiation or jet expansion would demand a ‘jet’ wider than its length and so inconsistent with narrow lines. In the case of radiative cooling, the resultant IR flux would exceed the observed values by a factor ?104.
  4. Light scattered on the jet grain mass required would be highly polarized, contrary to observations, unless the jet was optically thick to grains, again precluding their radiative cooling.
  5. To avoid unacceptable precessional broadening of the gamma-ray lines demands an emitting jet length ?0.5 days atv=0.26c. This increases the necessary mass loss rate by a factor ?10 over the values obtained by RKL who assumed a 4-day ‘flare’.
  6. The model also predicts rest energy gamma-ray lines which are not observed.
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12.
A clarification and discussion of the energy changes experienced by cosmic rays in the interplanetary region is presented. It is shown that the mean time rate of change of momentum of cosmic rays reckoned for a fixed volume in a reference frame fixed in the solar system is 〈p〉 =p V·G/3 (p=momentum,V is the solar wind velocity andG=cosmic-ray density gradient). This result is obtained in three ways:
  1. by a rearrangement and reinterpretation of the cosmic-ray continuity equation;
  2. by using a scattering analysis based on that of Gleeson and Axford (1967);
  3. by using a special scattering model in which cosmic-rays are trapped in ‘magnetic boxes’ moving with the solar wind.
The third method also gives the rate of change of momentum of particles within a moving ‘magnetic box’ as 〈pad = ?p ?·V/3, which is the adiabatic deceleration rate of Parker (1965). We conclude that ‘turnaround’ energy change effects previously considered separately are already included in the equation of transport for cosmic rays.  相似文献   

13.
We construct the maps of temperatures, geometrical thicknesses, electron densities and gas pressures in a quiescent prominence. For this we use the RGB signal of the prominence visible-light emission detected during the total solar eclipse of 1 August 2008 in Mongolia and quasi-simultaneous Hα spectra taken at Ond?ejov Observatory. The method of disentangling the electron density and geometrical (effective) thickness was described by Jej?i? and Heinzel (Solar Phys. 254, 89?–?100, 2009) and is used here for the first time to analyse the spatial variations of prominence parameters. For the studied prominence we obtained the following range of parameters: temperature 6000?–?15?000 K, effective thickness 200?–?15000 km, electron density 5×109?–?1011 cm?3 and gas pressure 0.02?–?0.2 dyn?cm?2 (assuming a fixed ionisation degree n p/n H=0.5). The electron density increases towards the bottom of the prominence, which we explain by an enhanced photoionisation due to the incident solar radiation. To confirm this, we construct a two-dimensional radiative-transfer model with realistic prominence illumination.  相似文献   

14.
Radio and X-ray observations are presented for three flares which show significant activity for several minutes prior to the main impulsive increase in the hard X-ray flux. The activity in this ‘pre-flash’ phase is investigated using 3.5 to 461 keV X-ray data from the Solar Maximum Mission, 100 to 1000 MHz radio data from Zürich, and 169 MHz radio-heliograph data from Nançay. The major results of this study are as follows:
  1. Decimetric pulsations, interpreted as plasma emission at densities of 109–1010 cm?3, and soft X-rays are observed before any Hα or hard X-ray increase.
  2. Some of the metric type III radio bursts appear close in time to hard X-ray peaks but delayed between 0.5 and 1.5 s, with the shorter delays for the bursts with the higher starting frequencies.
  3. The starting frequencies of these type III bursts appear to correlate with the electron temperatures derived from isothermal fits to the hard X-ray spectra. Such a correlation is expected if the particles are released at a constant altitude with an evolving electron distribution. In addition to this effect we find evidence for a downward motion of the acceleration site at the onset of the flash phase.
  4. In some cases the earlier type III bursts occurred at a different location, far from the main position during the flash phase.
  5. The flash phase is characterized by higher hard X-ray temperatures, more rapid increase in X-ray flux, and higher starting frequency of the coincident type III bursts.
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15.
We used merger trees realizations, predicted by the extended Press-Schechter theory, in order to study the growth of angular momentum of dark matter haloes. Our results showed that:
  1. The spin parameter λ′ resulting from the above method, is an increasing function of the present day mass of the halo. The mean value of λ′ varies from 0.0343 to 0.0484 for haloes with present day masses in the range of 109h?1 M to 1014h?1 M .
  2. The distribution of λ′ is close to a log-normal, but, as it is already found in the results of N-body simulations, the match is not satisfactory at the tails of the distribution. A new analytical formula that approximates the results much more satisfactorily is presented.
  3. The distribution of the values of λ′ depends only weakly on the redshift.
  4. The spin parameter of an halo depends on the number of recent major mergers. Specifically the spin parameter is an increasing function of this number.
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16.
An analysis of the data concerning high-velocity stars from Eggen's catalogue aimed at a determination of the approximate slope of the mass function for the spherical component of our Galaxy, and at estimating the local circular velocity, as well as the local rotation velocity, as by-products, has been performed. Our conclusions are that:
  1. A linear dependence of the mass on the radius is very likely;
  2. the value of the limiting radius is most likely equal to (40±10) kpc;
  3. the two local velocities are approximately equal to each other, being both equal to (230±30) km s?1;
  4. the local escape velocity appears to be most likely equal to (520±30) km s?1;
  5. the total mass of a corona, obtained in this way, is (5±1)×1011 M .
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17.
Sample 14307,30, a gas-rich breccia (Group 1 of Warner, 1972) has been studied by coupling track method and light noble gas isotopic analysis. The breccia is made of a glassy dark matrix with embedded millimeter to sub-millimeter sized angular ligth xenoliths. These ones are breccia fragments of higher grade metamorphic facies (Group ? 2). A lighter strata (~ 0.5 cm thick) intersects the dark matrix. Noble gas analysis have shown the dark matrix (36Ar = 5.4 × 10?4 cc STP/g) to be enriched in solar type gases with respect to the light fractions (36Ar ? 2.2 × 10?4 cc STP/g). Themean value of the bulk ‘exposure age’ for different samplings is 180 ± 20 × 106 yr, as calculated from spallogenic3He,21Ne and126Xe contents, using our data and those of Bogard and Nyquist (1972). After appropriate correction for radiogenic40Ar, the ratio40Arexc/36Artr is about 5. A total of 390 crystals coming from 11 locations either in the dark matrix, the lighter strata or a light xenolith (0.25 cm diam), have been studied by track analysis using optical and scanning electron microscopy. 181 crystals were thoroughly investigated by means of the latter technique. The following results were obtained:
  1. 72 crystals (70-300µm diam) from one location (No. 12) in the matrix show aminimum track density distribution spreading over 3 orders of magnitude (from 2 × 106 up to 2 × 109 cm?2). The spectrum has at its lower edge a well defined peak (~ 50% of total crystal number) around 3 × 106 cm?2). Grains with track density variations over a factor of 3 have a low abundance as compared to average lunar soils. Moreover the mineralogy of this location is peculiar due to its large abundance in orthopyroxenes. Considering the lower edge of the track density distribution amaximum surface residence time of 5 × 106 yr can be set for rock 14307 in itspresent shape;
  2. 11 feldspars (1-15µm diam) and 22 clinopyroxenes (70-130µm) have been studied in the light xenolith. All crystals have minimum track densities larger than 108 cm?2. No spatial variation of track-densities (2.5 ± 0.5 × 109 cm?2) were found in feldspars inside a millimeter-sized polished section. Clearly these tracks were not acquired by an irradiation of the xenolith as an individual entity, but survived its own formation as a breccia of Group 2. Therefore, solar energetic iron particle tracks have not been erased despite a complex mechanical and thermal history involved by two subsequent brecciation processes;
  3. in the 10 other locations, crystals (70-200µm diam) either from the dark matrix or the lighter strata show a significant departure from the pattern observed in lunar soils; namely:
  1. the minimum track density distribution is strongly peaked at high values (~ 1-4 × 109 cm?2) for ~ 95% of the crystals, the remaining ~ 5% having low-values (0.2-1 × 107 cm?2);
  2. the abundance (2%) of crystals with track density variation over a factor of 3 is about one order of magnitude less than in average lunar soils;
  3. the magnitude of track density gradients within single crystals is small. In fact, thelargest track density variation versus depth found can be described by the relation? α D?0.5, in contrast with soil grains which generally exhibit a variation of the form? α D?1.1±0.4.
The above observations imply that the peculiar irradiation characteristics of these fossilized soils are more likely to be attributed to some wide scale process rather than to some accidental or local phenomena. Attempts to account for these findings by present solar VH particle flux and energy distribution (as determined by Crozaz and Walker, 1971; Fleischeret al., 1971b; Priceet al., 1971), current estimates of lunar fine scale erosion, accumulation and turn-over rates, have proven essentially negative. The bulk ‘exposure age’ of the breccia, rather low by lunar soil standards, makes things even worse. For lack of any better explanation, the above observations could be more easily understood by postulating a higher flux (by factors from ~ 10 up to 200) and a harder energy spectrum (at least for particles with rigidity less than 0.3 GV) for the solar cosmic rays at the time the constituents of the breccia were part as loose grains of the lunar regolith.  相似文献   

18.
Letr 1,r 2,r 3 be arbitrary coordinates of the non-zero interacting mass-pointsm 1,m 2,m 3 and define the distancesR 1=|r 1?r 3|,R 2=|r 2?r 3|,R=|r 1?r 2|. An eight-dimensional regularization of the general three-body problem is given which is based on Kustaanheimo-Stiefel regularization of a single binary and possesses the properties:
  1. The equations of motion are regular for the two-body collisionsR 1→0 orR 2→0.
  2. Provided thatR?R 1 orR?R 2, the equations of motion are numerically well behaved for close triple encounters.
Although the requirementR? min (R 1,R 2) may involve occasional transformations to physical variables in order to re-label the particles, all integrations are performed in regularized variables. Numerical comparisons with the standard Kustaanheimo-Stiefel regularization show that the new method gives improved accuracy per integration step at no extra computing time for a variety of examples. In addition, time reversal tests indicate that critical triple encounters may now be studied with confidence. The Hamiltonian formulation has been generalized to include the case of perturbed three-body motions and it is anticipated that this procedure will lead to further improvements ofN-body calculations.  相似文献   

19.
The properties of small (< 2″) moving magnetic features near certain sunspots are studied with several time series of longitudinal magnetograms and Hα filtergrams. We find that the moving magnetic features:
  1. Are associated only with decaying sunspots surrounded entirely or in part by a zone without a permanent vertical magnetic field.
  2. Appear first at or slightly beyond the outer edge of the parent sunspot regardless of the presence or absence of a penumbra.
  3. Move approximately radially outward from sunspots at about 1 km s?1 until they vanish or reach the network.
  4. Appear with both magnetic polarities from sunspots of single polarities but appear with a net flux of the same sign as the parent sunspot.
  5. Transport net flux away from the parent sunspots at the same rates as the flux decay of the sunspots.
  6. Tend to appear in opposite polarity pairs.
  7. Appear to carry a total flux away from sunspots several times larger than the total flux of the sunspots.
  8. Produce only a very faint emmission in the core of Hα.
A model to help understand the observations is proposed.  相似文献   

20.
Radiation from an optically thick, tenuous, isothermal and magnetized plasma is considered under conditions typical for X-ray pulsars, in the approximation of coupled diffusion of normal modes. The spectra are calculated of the fluxes and specific intensities of outgoing radiation, their dependences on the plasma densityN, temperatureT and magnetic fieldB are analysed with due regard to the vacuum polarization by a strong magnetic field. Simple analytical expressions are obtained in the limiting cases for the fluxes and intensities. It is shown that atE B »E a (E B =11.6B 12 keV,E a ?0.1N 22 1/2 T 1 ?3/4 keV,B 12=B/1012 G,N 22=N/1022 cm?3,T 1=T/10 keV) the magnetic field strongly intensifies the flux and changes its spectrum in the regionE a ?E ?E B . AtE ?T the spectrum of the energy flux is almost flat in the region \(\sqrt {E_a E_B } \lesssim E \lesssim E_B \) . For homogeneous plasma without Comptonization the cyclotron line atE?=E B appears in emission, though in many other cases it may appear in absorption. The vacuum polarization may produce the ‘vacuum feature’ atE?E W ?13N 22 1/2 B 12 ?1 keV, which, as a rule, appears in absorption. The intensity spectra vary noticeably with the direction of radiation, in particular, at some directions nearB, the spectra become harder than in other directions. Quantization of the magnetic field (E B >T) strongly increases the plasma luminosity (∝E B /T for homogeneous plasma). The results obtained explain a number of basic features in the observed X-ray pulsar spectra.  相似文献   

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