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1.
, () , , ( =2) , . (, , ). ( =0,5) .  相似文献   

2.
Hong Wei Li 《Solar physics》1986,104(1):131-136
The variations of the growth rates of ECM at first four harmonics in X-, Z-, and O-modes excited by a hollow beam distribution of weakly relativistic electrons with a parameter p / e are presented in this paper. The results show that the second harmonic of ECM in X-mode dominates the instability if < 1, and if 1.2 , 2 or 2.2 3 the third or fourth harmonic will dominate. The second and third harmonics of Z-mode waves grow faster only if 2 2.2 and 3 3.2, respectively, so it would not be a competition in most cases. It is suggested that the ECM emission at these harmonics in X-mode is a possible mechanism to produce solar spike emissions with high brightness temperature at shorter and longer decimetric wavelengths.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.On leave from the Department of Astronomy, Nanjing University, Nanjing, The People's Republic of China.  相似文献   

3.
The RS CVn binary stellar system HR 1099 is a source of both X-ray and radio flares. We present here a model of the system in which the two types of flare are produced by the same population of mildly-relativistic ( 10) electrons, injected into a coronal loop. After reviewing possible radiation mechanisms we conclude that, given the probable conditions in the flaring region, the radio emission is gyrosynchrotron radiation and the X-ray emission is thermal bremsstrahlung. The thermal X-ray source must lie in the stellar chromosphere, but the apparent absence of plasma absorption at radio frequencies indicates that the radio source is located high in the coronal loop. Using the relationships given by Dulk and Marsh (1982) for the radio emission from a power-law electron energy spectrum,N() ( - 1)–, we conclude that 3 7, with 30% of the electron population trapped in the radio source. Some implications of these results for one particular version of the model are discussed.  相似文献   

4.
Kane  S. R.  Kreplin  R. W.  Martres  M. -J.  Pick  M.  Soru-Escaut  I. 《Solar physics》1974,38(2):483-497
The relationship between H absorption features, type III radio bursts and soft X-ray emission has been examined in order to determine the characteristics of the particle acceleration process operating when a H-flare may not be detectable. It is found that transient H activity observed in the absence of reported flares is associated with production of relatively weak type III radio and soft X-ray emission. Since such optical phenomena are much more frequent than flares themselves, it is concluded that instabilities generating fast particles may be produced in the corona in a quasi-continuous way with coincident perturbations in the lower solar atmosphere.The soft X-ray component, which is similar to the precursor in flares, is not necessarily the direct product of fast particles, but is probably associated with some type of heating since both the soft X-ray emission and the H features exhibit a similar evolution, the type III bursts occurring near the maximum of this perturbation. The observations are consistent with a model in which the electron acceleration region is located at an altitude where the ion density is 109 cm–3 and most of the accelerated electrons( 20 keV) are confined to coronal altitudes where the ion density is 1010 cm–3.  相似文献   

5.
The equation of state and the adiabatic index of thermally dissociated matter composed of nucleons, electrons, positrons, neutrinos, antineutrinos and photons are calculated in the density and temperature ranges, 109q(g cm–3)1013, 2×1010T K5×1011, respectively. The interaction between nucleons is explicitly included. This leads to a softening of the equation of state. The implications of the results for the problem of supernova collapse are discussed.  相似文献   

6.
A re-analysis of the diffuse far UV radiation ( 1350–1480 Å) observed in the sky region ofl II180° and 0°b II40° is presented, as a revised version of a paper by Hayakawaet al. (1969). In comparison with the previous one, the value of the half optical depth of the Galazxy in our wavelength region is reduced, and the values of the albedo coefficient and the forward phase functiong are not well determined. If, however, we combine our results with the theoretical model of interstellar grains by Gilra, the value of is given by 0.13(5)0.18(5).  相似文献   

7.
A number of suggestive coincidences are found in a purely speculative analogy between the by-products, of a minihole fast evaporation in a plasma, and by-products from flares at magnetospheres. Solar flares might serve as good examples. From an observational point of view our attention is drawn to the considerable extent of the blank time interval existing between known before and after evidences on flares, during which some exotic energy conversion processes could be invoked to explain the large amount of energy released in time-scales that might be very short. We suggest that fundamental progress in the knowledge of energy conversion, processes in flares require observational data with a time resolution several orders of magnitude, better than the currently available data, particularly, for hard X-rays.  相似文献   

8.
Energy spectra of cosmic ray nuclei in the charge range 5Z26 have been derived from the response of an acrylic plastic erenkov detector. Data were obtained using a balloon-borne detector and cover the energy range 320E2200 MeV amu–1. Spectra are derived from a formal deconvolution using the method of Lezniak (1975). Relative spectra of different elements are compared by observing the charge ratios. Secondary-primary ratios are observed to decrease with increasing energy, consistent with the effect previously observed at higher energy. Primary-to-primary ratios are constant for 6Z10 and 14Z26 but vary for 10Z14. This data is found to be consistent with existing data, where comparable, and lends strong support to the idea of two separate source populations contributing to the cosmic ray composition.Work supported by University of Maryland Grant NGR 21-002-316.  相似文献   

9.
The fluxes and spectra of galactic and extragalactic neutrinos at energy 1011–1019 eV are calculated. In particular, the neutrino flux from the normal galaxies is calculated taking into account the spectral index distribution. The only assumption that seriously affects the calculated neutrino flux atE v 1017 eV is the power-like generation spectrum of protons in the entire considered energy region.The normal galaxies with the accepted parameters generate the metagalactic equivalent electron component (electrons+their radiation) with energy density e8.5×10–7 eV cm–3, while the density of the observed diffuse X-ray radiation alone is 100 times higher. This requires the existence of other neutrino sources and we found the minimized neutrino flux under two limitations: (1) the power-law generation spectrum of protons and (2) production of the observed energy density of the diffuse X-an -radiation. These requirements are met in the evolutionary model of origin of the metagalactic cosmic rays with modern energy density M83.6×10–7 eV cm–3.The possibility of experiments with cosmic neutrinos of energyE v 3×1017 eV is discussed. The upper bound on neutrino-nucleon cross-section <2.2×10–29 cm2 is obtained in evolutionary model from the observed zenith angular distribution of extensive air showers.In Appendix 2 the diffuse X-and -ray flux arising together with neutrino flux is calculated. It agrees with observed flux in the entire energy range from 1 keV up to 100 MeV.  相似文献   

10.
Thermonuclear reaction rates are calculated at temperatures consistent with nucleosynthesis conditions in stars and supernovae (109T1010 K). The cross sections as a function of energy are determined by averaging over a density of compound nuclear states, an individual resonance contribution being represented by the Breit-Wigner formula. The proton and -particle channel radii are estimated by fitting experimental (p, n) and (, n) cross sections for nuclei in the mass range 40A200. The influence of the diffuseness of the nuclear surface on barrier penetration is taken into account by multiplying the square well penetration factors by a reflection factor in the manner described by Vogtet al. (1965). Thermonuclear rates calculated by these procedures are compared with sums over experimentally determined resonance strengths for a number of charged-particle reactions involving medium mass nuclei (24A40).  相似文献   

11.
The reaction rates for the proton-proton reaction and the related electron capture reaction in a strongly magnetized relativistic electron gas of arbitrary degree of degeneracy are computed. The proton-proton reaction rates are unaffected by the presence of the magnetic field for field strengths up to the critical valueH q =m 2 c 3/e=4.414×1013G. For fields greater thanH q , the proton-proton reaction rates are enhanced linearly with (=H/H q ).The PeP reaction is investigated in detail for a wide range of temperatures, densities and magnetic field strengths that are of interest. The main results are as follows: In the non-degenerate regime the reaction rates are significantly reduced for high temperatures (T 95) and low fields (1). For instance, pep(H)=0.04 pep(O) at =10–3,T 9=10. For relatively high fields (>1) and low temperatures (T 92), the reaction rates are enhanced approximately linearly with . In the complete degenerate regime the reaction rates are reduced up to one-third of the field-free value for moderate densities (6/e10). At high densities (6/e10) the reaction rates are unaffected by the magnetic field.  相似文献   

12.
1937 - (, 1938). , , , , . , . . (, 1938), , . - (, 1938; Szebehely, 1967)., , . . - (, 1938), . — — . , , . , . . , . , , . . (, 1944). , .
In 1937, the Celestial Mechanics and Cosmogony section of the Sternberg State Astronomical Institute undertook the task of evaluating the Gylden-Moulton hypothesis on the origin of the Gegenshein from the standpoint of celestial mechanics. That investigation, which the authors themselves considered preliminary, contains nonetheless a series of important results. For example, G. N. Duboshin showed that in the planar, circular, restricted three-body problem, periodic motion of finite amplitude in the neighborhood of a collinear libration point is unstable according to Lyapunov's criterion both in the proper and in the orbital sense. The latter result is incompatible with the above named hypothesis, and thus appears as one of the serious objections among the many known negative conclusions relative to the existence of the Gylden-Moulton cluster.Unfortunately, most of the specific problems which arose in the above named research have not been considered since. One of these, the problem of the stability of three-dimensional periodic orbits in the neighborhood of a collinear libration point is solved in the present paper, within the limits of the three-dimensional, circular, restricted, three-body problem. Major attention is given to the investigation of stability in the orbital sense, since in the proper sense all orbits are unstable according to Lyapunov theory. It is shown that in order to resolve the question of stability, it is sufficient to consider the equations in their variational form. Analysis of the roots of the corresponding characteristic equations determines the orbital stability of planar and three-dimensional solutions, which later can be confirmed by calculation of the characteristic exponents appearing in the periodic solutions of the N. A. Artemiev method. Finally, the possibility of conditional stability in the linear approximation is proved.
  相似文献   

13.
Stepanov  A.V.  Tsap  Y.T. 《Solar physics》2002,211(1-2):135-154
Interaction of the 30–300 keV electrons with whistlers in solar coronal loops is studied using a quasi-linear approach. We show that the electron–whistler interaction may play a dominant role in the formation of fast electron spectra within the solar flare loops with the plasma temperature 107 K and plasma density 1011 cm–3. It is found that Landau damping of whistlers provides weak and intermediate pitch-angle diffusion regimes of fast electrons in coronal loops. The level of whistler turbulence in the weak diffusion regime under flare conditions is estimated as 10–7 of the energy density in the thermal particles. The `top – footpoint' relations between the hard X-ray flux densities and spectra are derived. The reason for a `broken' spectrum of the flare microwave emission is discussed.  相似文献   

14.
A study is made of Lyman continuum observations of solar flares, using data obtained by the Harvard College Observatory EUV spectroheliometer on the Apollo Telescope Mount. We find that there are two main types of flare regions: an overall mean flare coincident with the H flare region, and transient Lyman continuum kernels which can be identified with the H and X-ray kernels observed by other authors. It is found that the ground level hydrogen population in flares is closer to LTE than in the quiet Sun and active regions, and that the level of Lyman continuum formation is lowered in the atmosphere from a mass column density m 5/sx 10–6 g cm–2 in the quiet Sun to m 3/sx 10–4 g cm–2 in the mean flare, and to m 10–3g cm–2 in kernels. From these results we derive the amount of chromospheric material evaporated into the high temperature region, which is found to be - 1015g, in agreement with observations of X-ray emission measures. A comparison is made between kernel observations and the theoretical predictions made by model heating calculations, available in the literature; significant discrepancies are found between observation and current particle-heating models.  相似文献   

15.
As a possible mechanism for particle acceleration in the impulsive phase of solar flares, a new particle acceleration mechanism in shock waves is proposed; a collisionless fast magnetosonic shock wave can promptly accelerate protons and electrons to relativistic energies, which was found by theory and relativistic particle simulation. The simultaneous acceleration of protons and electrons takes place in a rather strong magnetic field such that ce pe . For a weak magnetic field ( ce pe ), strong acceleration occurs to protons only. Resonant protons gain relativistic energies within the order of the ion cyclotron period (much less than 1 s for solar plasma parameters). The electron acceleration time is shorter than the ion-cyclotron period.  相似文献   

16.
Type III radio bursts observed at kilometric wavelengths ( 0.35 MHz) by the OGO-5 spacecraft are compared with > 45 keV solar electron events observed near 1 AU by the IMP-5 and Explorer 35 spacecraft for the period March 1968–November 1969.Fifty-six distinct type III bursts extending to 0.35 MHz ( 50 R equivalent height above the photosphere) were observed above the threshold of the OGO-5 detector; all but two were associated with solar flares. Twenty-six of the bursts were followed 40 min later by > 45 keV solar electron events observed at 1 AU. All of these 26 bursts were identified with flares located west of W 09 solar longitude. Of the bursts not associated with electron events only three were identified with flares west of W 09, 18 were located east of W 09 and 7 occurred during times when electron events would be obscured by high background particle fluxes.Thus almost all type III bursts from the western half of the solar disk observed by OGO-5 above a detection flux density threshold of the order of 10–13 Wm–2 Hz–1 at 0.35 MHz are followed by > 45 keV electrons at 1 AU with a maximum flux of 10 cm–2 s–1 ster–1. If particle propagation effects are taken into account it is possible to account for lack of electron events with the type III bursts from flares east of the central meridian. We conclude that streams of 10–100 keV electrons are the exciting agent for type III bursts and that these same electrons escape into the interplanetary medium where they are observed at 1 AU. The total number of > 45 keV electrons emitted in association with a strong kilometer wavelength type III burst is estimated to be 5 × 1032.  相似文献   

17.
Light-element abundances are compiled for six peculiar A stars (3 CenA, 2 CVn, HR 1732,v For, Cnc, and 112 Her) with Heilines very weak for their colours. The abundances are interpreted on the theory that peculiar A stars were once secondaries in binary systems in which the primaries exploded as type II supernovae. During the explosions of the primaries, protons were accelerated to high energies (>20 MeV) in shock waves at the secondaries, and spallation of He, C, N, and O occurred. This was followed by the arrival of heavier elements from the primaries. Abundances on 2 CVn, HR 1732, andv For were subsequently modified by surface nuclear reactions involving protons and -particles accelerated to lower energies (10 MeV), probably by magnetic fields. Successive (, ) reactions formed Si28 from Ne20, and (p, ) reactions acting on A40 and Ca40 may have contributed to the excesses of Cl observed on 2 CVn and HR 1732. These proposals have interesting implications with regard to the relative abundances of the iron-peak elements found on peculiar A stars and in the Solar System.  相似文献   

18.
R. P. Lin 《Solar physics》1982,113(1-2):217-220
We present observations of an intense solar flare hard X-ray burst on 1980 June 27, made with a balloon-borne array of liquid nitrogen-cooled germanium detectors which provided unprecedented spectral resolution (1 keV FWHM). The hard X-ray spectra throughout the impulsive phase burst fitted well to a double power-law form, and emission from an isothermal 108–109K plasma can be specifically excluded. The temporal variations of the spectrum indicate that the hard X-ray burst is made up of two superposed components: individual spikes lasting 3–15 s, whch have a hard spectrum and a break energy of 30–65 keV; and a slowly varying component characterized by a soft spectrum with a constant low-energy slope and a break energy which increases from 25 keV to 100 keV through the event. The double power-law shape indicates that acceleration by DC electric fields parallel to the magnetic field, similar to that occurring in the Earth's auroral zone, may be the source of the energetic electrons which produce the hard X-ray emission. The total potential drop required for flares is typically 102 kV compared to 10 kV for auroral substorms.  相似文献   

19.
Attention is given to the radiation of microwaves by charged dust in space. Presently-used particle distributions do not restrict the presence in space of large numbers of small (r<10–6 cm) silicate grains, but it is shown that such densities (10–25–10–26 g cm–3) of small grains would produce a microwave background with an energy density of the same order of magnitude as the energy density of the (presumed) cosmological 3 K background. Limits set by the isotropy of the latter are: (HI clouds)10–26, (Galactic plane)10–30, (Halo)10–32, (Local Group)10–34 g cm–3. These limits imply that either there is a cutoff in particle distributions atr10–6 cm, or that the density of silicate grains in space has been generally overestimated, or that cosmic rays have broken up a lot of grains so that they now form a population of grains of very small size (10–7 cm) which are difficult to detect by conventional methods. One way to look for the latter population is by studying expected distortions of the 3 K spectrum to the short wavelength side of the portion hitherto observed (grains may have a size distribution able to give an approximate black-body curve for radiation from larger grains of 10–6 cm size), and by testing the effective energy density of the 3 K field in other galaxies.  相似文献   

20.
High resolution OVRO CO 1–0 observations of the inner 30 in the LINER galaxy NGC 5218 reveal the presence of a double centrally peaked molecular concentration with extensions out to a radius of 12. The molecular mass detected is 2.4 × 109 M and the gas surface density is high, 3000 M pc square in the inner 500 pc. The SFR is 2–3 M yr–1 and the SFE is 13, which are low or moderate values for that gas surface density. We interpret the inner feature as a rotating molecular ring with a radius of 200 pc. We furthermore suggest that the LINER activity in NGC 5218 is not caused by an aging starburst, but by a buried AGN.  相似文献   

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