共查询到20条相似文献，搜索用时 31 毫秒
1.
Marco Missana 《Astrophysics and Space Science》1979,61(2):277-286
The analysis of the Skylab measurements on the ultraviolet limb spectra confirm the presence of a generalized Compton effect in the solar spectrum which can be explained by Thomson scattering theory. The present measurements on the Orion spectrum and interstellar line towards -Arae give a large generalized Compton effect which could be explained by a resonance scattering theory. These numerical results cannot be due to random errors in the measurements, as follows from the statistical discussion. The need for further measurements is pointed out. 相似文献
2.
M. Missana 《Astrophysics and Space Science》1975,33(1):239-243
We assume that the lines of the solar spectrum, formed in the reversing layer, when travelling for an optical thickness τ in the chromosphere are subjected to a red shift Δλ(τ) due to multiple Compton scattering. We limit our investigation to the difference of the red shift at the limb—the red shift at the centre of the disc giving a good agreement between the theoretical results and observations. 相似文献
3.
It is demonstrated that in the case of hard injection of relativistic electrons accompanied by the joint action of synchrotron (Compton) losses and energy-dependent spatial diffusion, a spectrum with breaks is formed containing universal (with index =2) and diffusion regions, both independent of the injection spectrum. The effect from non-linearity of the electron spectrum is considered in averaged electromagnetic spectra for various geometries of sources (sphere, disk, arm). It is shown that a universal region (with index =0.5) can occur in the radiation spectrum. 相似文献
4.
Simulation calculations have been made to examine the modification effect of a hot X-ray photon field on a-ray spectrum by the photon-photon pair production and inverse Compton scattering processes. The Cyg X-3 system was used as a paradigm. It is shown that a-ray spectrum can change significantly when passing through the ambient keV X-ray photon field of an accretion binary source. For Cyg X-3, a significant amount of r-rays originated near the central source in the range of 102-104 MeV could be absorbed by the extended X-ray photons from accretion disk corona in a high X-ray luminosity state and, on the other hand, the inverse Compton effect of secondary electrons could cause a considerable increase in intensity of-rays between ~ 10 MeV and ~ 50 MeV. The relevance of the absorption effect for observations is discussed. 相似文献
5.
Wavelength shifts converted to velocities between solar lines observed at disc center and laboratory wavelengths of Fei, Feii, Tii, Nii, and Fei lines in the near infrared are plotted as a function of the logarithm of their solar equivalent width in milliångstroms. The need for wavelengths based on the wavelength standards is stressed. A comparison of photographic Fei solar wavelength is shown to agree, on the average, with Fourier Transform Spectrometer solar wavelengths within less than 0.5 milliångstroms. Using Balthasar's limb effect tables we convert the disc center velocities to limb velocities and find, though the scatter is large, that there is little evidence for a super-gravitational red shift. 相似文献
6.
It is shown that, by sufficiently high-power -radiation (in particular, that of -ray Compton effect origin) photonuclear reactions can substantially alter the chemical abundance of material in the central region of the quasars. The absence of observed distortion of the chemical composition of the emitting regions of quasars constitutes an evidence for the effective mixing of plasma in central regions of the quasars, and/or for the diminishing Compton loss on account of the radial magnetic fields. 相似文献
7.
J. L. Leroy 《Solar physics》1974,36(1):81-84
The polarization of light observed near the Sun's limb steeply goes down from the blue to the red part of the spectrum. New measurements performed through near-infrared filters (the characteristics of which are displayed in Table I) have shown that this behaviour holds up to 8000 Å (Table II). On the other hand, we have found that the proportion of polarized light remains nearly constant between 8000 and 10000 Å; it is about 15 millionths at 25 from the limb, at least if our measurements have not been biased by any unknown polarizing process in the terrestrial atmosphere 相似文献
8.
The well-known correlation between granulation intensity and velocity fluctuations causes a shift of the average line position called the convective blue shift. It is argued that this convective blue shift is most likely reponsible for the limb effect of solar Fraunhofer lines. To explain the center-to-limb variation of this limb effect it is essential that both horizontal and vertical motions in the granulation are considered. The effects of a variation in the granulation properties across the Sun on large scale velocity pattern observations are discussed. Abnormal granulation patterns observed inactive regions and at the boundaries of supergranules could be responsible for part or all of the downflow observed there.On leave from Astronomy Department, University of Washington, Seattle, Wash., U.S.A.Operated by the Association of Universities for Research in Astronomy, Inc. under contract AST 74-04129 with the National Science Foundation. 相似文献
9.
A Monte Carlo program has been developed in order to examine the influence of multiple Compton scattering in the atmosphere on the spectrum of cosmic diffuse gamma rays. It is shown that the corrections to the made to the measurements of the double-Compton gamma telescope at 2·5 gr cm–2 rest atmosphere by Schönfelder and Lichti (1974) are lower than 4% in the energy range between 1.5 and 10 MeV.Under support of a fellowship by the Deutscher Akademischer Austauschdienst 相似文献
10.
R. Grant Athay 《Solar physics》1990,126(1):135-152
Selected Civ
V
0 lines (lines separating adjacent regions of strong blue shift and strong red shift) located near the solar limb and oriented parallel to the radius vector from disk center are shown to be closely aligned with H dark filaments in active regions. The filaments, in turn, are known to lie in the vicinity of magnetic neutral lines. The radial orientation of the V
0 lines minimizes uncertainties in image registration and their location near the limb ensures that the observed fluid motion has major components paralleling V
0. It follows that the filaments are located at sites of velocity shear, and, by inference, of magnetic shear. For a case in which a given V
0 line is observed near both east and west limbs, the gradient of Doppler velocity across the V
0 line reverses sign from one limb to the other as is expected for horizontal steady flow. Thus, the velocity vectors remain fixed with respect to the filament.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
11.
The normal mode spectrum for the linearized MHD equations is investigated for a cylindrical equilibrium. This spectrum is examined for zero perpendicular thermal conduction, with both zero and non-zero scalar resistivity. Particular attention is paid to the continuous branches of this spectrum, or continuous spectra. For zero resistivity there are three types of continuous spectra present, namely the Alfvén, slow, and thermal continua. It is shown that when dissipation due to resistivity is included, the slow and Alfvén continua are removed and that the thermal continuum is shifted to a different position (where the shift is independent of the exact value of resistivity). The old location of the thermal continuum is covered by a dense set of nearly singular discrete modes called a quasi-continuum. The quasi-continuum is investigated numerically, and the eigenfunctions are shown to have rapid spatial oscillating behaviour. These oscillations are confined to the most unstable part of the equilibrium based on the Field criterion, and may be the cause of fine structure in prominences. 相似文献
12.
We employ limb darkening, spectral energy distribution (color), and center-disk spectrum line strength to investigate photospheric temporal variability. Current limb-darkening curves agree to 1% with past observations taken at different epochs extending back to 1975. Concerning color, from the data of Labs and Neckel (Cox, 1999) we deduce that the solar limb is 1000 Å more red than disk center. But when integrated over the entire disk to represent the Sun-as-a-star, the color shift is only 30 Å. Color is therefore not a very sensitive indicator of full-disk photospheric change. We examine the center-disk time series for C 5380 Å and Fe 5379 Å equivalent width and the Ca K index. The ratio C 5380/Fe 5379 in equivalent width is 0.4221+0.00011 (±0.00003) y
–1, indicating secular change but with no cycle modulation. Converted to temperature this variance amounts to ±0.028 K. This is in contrast to the full-disk cycle modulation of these lines reported by Gray and Livingston (1997b). Ca K index also exhibits no cycle variation at disk center. Taking into account these findings, plus the small fraction of the photosphere occupied by magnetic elements as revealed in high-resolution G-band pictures, we suggest that cycle magnetic fields thread through the basal atmosphere without physical effect; that the basal quiet atmosphere is observationally immutable to the magnetic cycle within the limits given above. 相似文献
13.
The formation of steady-state spectra of radiation or particles by Compton scattering is discussed for the case when the flux from the source is present. Power-law distributions, or those characterized by a power-law asymptotic behaviour, can appear under these conditions.The power indices and normalizations have been found as well as the flux directions for the electron and photon distributions in two cases. The first case is that of differential energy transfer over the electron spectrum (interaction with soft radiation). For the case of integrated transfer, relations have been found between the indices.The possibility of a power-law electron spectrum (with an index =2) has been shown for scattering by equilibrium radiation (the black-body background included). 相似文献
14.
G. N. Dzhimsheleishvili 《Astrophysics》1971,7(3):216-224
Conclusions Our observations permit certain conclusions concerning the changes that occurred in the spectrum of CH Cyg during the observation period. It was found that, in conformity with the results of [14], the relative monochromatic brightness and continuous radiation in the violet vary in general as a function of the variation of emission in H (Figs. 6 and 5; the graph of the variation of emission in H is given only in Fig. 6). But continuous radiation in the violet decreases slowly with fluctuations and does not disappear with the end of the outburst. The curves of the relative monochromatic brightness in different light change differently (Fig. 6).As regards the excesses of continuous radiation in red, green, and blue (Figs. 3–5), we attributed their presence in the spectrum partially to the effect of the red component of CH Cyg. This follows from the fact that these excesses were observed before the outburst, and during the outburst the green and blue excesses decreased in general. In addition, the red excess does not duplicate exactly the variations of hydrogen emission. This is also noted in [16], where it is shown that the variation in V is greater than in r, whereas the contribution of the Balmer and Paschen hydrogen emission to V is less than to r. Therefore, part of the red and violet excesses should be attributed to the effect of the red component.Abastumani Astrophysical Observatory. Translated from Astrofizika, Vol. 7, No. 3, pp. 363–375, July–September, 1971. 相似文献
15.
Stanisław Bellert 《Astrophysics and Space Science》1969,3(2):268-282
An attempt is presented to explain the red shift in terms of a theory based on two postulates: (1) perfect cosmological principle, and (2) postulate of the uniqueness of electromagnetic wavelength measurements. It is assumed that the space of events is a static space, and the red shift is a consequence of the geometry of that space. In terms of the accepted postulates a theorem has been proved, according to which the luminosity distanceD is related to the red shift Δλ/λ0 by $$D = cT\frac{{\Delta \lambda /\lambda _0 }}{{1 + \Delta \lambda /\lambda _0 }},$$ wherec is the light velocity, andT, the Hubble constant. It is shown that this relation is in agreement with astronomical data concerning the red shift and the distribution of galaxies. The hypothesis does not lead to the necessity of accepting any assumptions concerning the creation of matter at the origin of time or a continuous creation of matter, which have been postulated by certain other theories. 相似文献
16.
The effect of Thomson scattering and Compton effect on the shape of a spectral line is studied in the case of a plane-parallel atmosphere. The theoretical values of red shift and intensity at the top of the line, having an equivalent width 5√π10?10 cm, and of the red asymmetry are tabulated for 62 different values of the optical thickness τ′; from τ′=0.2/√3 to τ′=2.6/√3. The case of solar atmosphere is considered and it is shown that all main features of the observed red shifts can be interpreted by means of a scattering theory, with an error smaller than one milliängström. The need of further measurements is pointed out. 相似文献
17.
Ludwig Oster 《Astrophysics and Space Science》1968,2(4):438-447
A computation is presented that predicts with sufficient accuracy the energy transfer between relativistic electrons and radio photons by means of stimulated Compton events. It is shown that the majority of currently assumed parameters for quasi-stellar objects result in situations where the relativistic electrons must be producedinitially at rather high energies (102–103) in order to survive for any appreciable length of time. 相似文献
18.
A. A. Pevtsov 《Solar physics》1992,141(1):65-73
Using observational data on 14 sunspots from the Sayan Observatory vector magnetograph, a study was made of the relationship between the sunspot magnetic field and the Evershed motions. It is shown that the central area of the solar disk is dominated by an anti-correlation of the longitudinal magnetic field B
and the line-of-sight velocity V
when a maximum of V
corresponds to the neutral line of the longitudinal field. Near the limb there usually is a coincidence of the field and velocity neutral lines. There is evidence for the possible asymmetric character of the effect with respect to the central meridian. 相似文献
19.
Y. P. Varshni 《Astrophysics and Space Science》1976,43(1):3-8
It is shown that the cosmological interpretation of the red shift in the spectra of quasars leads to yet another paradoxical result: namely, that the Earth is the center of the Universe. Consequences of this result are examined.Einstein distinguishes between two main criteria [for a good theory]: (a) theexternal confirmation of a theory, which informs us in experimental checks of the correctness of the theory, and (b) theinner perfection of a theory which judges its logical simplicity or naturalness. 相似文献
20.
We present an analysis of the reported spectral features of NGC 4151 in X-rays. It is shown that the origin of X-rays from the source is inconsistent with a single production mechanism. We suggest a new two-component model in which soft X-rays arise from the black-body emission of a tiny hot nucleus withT2×107 K and the hard X-ray photons are generated in an extended region by inverse Compton scattering of electrons with the infrared photons. 相似文献