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1.
S. Hayakawa T. Kato T. Kohno K. Nishimura Y. Tanaka K. Yamashita 《Astrophysics and Space Science》1972,17(1):30-38
Cosmic X-rays in the energy range between 0.210 keV were observed with polypropylene window proportional counters on board a sounding rocket. The field of view crossed the galactic plane in the Sgr region and reached galactic latitudes of 50° and –90°. A new soft X-ray source was found in the Aries-Taurus region. The soft X-ray flux from the direction of NGC 1275 was conspicuous, whereas that of Sgr region source were very weak. The distribution of the intensity of diffuse soft X-rays over the scanned region indicates the galactic emission of soft X-rays. 相似文献
2.
The 2B/X2.8 double-ribbon flare of 30 March, 1982 is investigated using H, white light, X-rays, and microwaves. The X-ray burst seems to consist of two components, i.e., an impulsive component showing a long chain of peaks and a thermal component (T 2 × 107 K).In the early phase, the source images for the impulsive component were available simultaneously at soft (7–14 keV) and hard (20–40 keV) X-rays. Both sources are elongated along a neutral line. The core of the source for the hard X-rays is located at one end which seems to be a footpoint (or a leg) of a loop or arcade, while the core for the soft X-rays is located at the center of the elongated source which would be the center of the loop. The core for the hard X-rays shifted to this center in the main and later phase, accompanied by decrease in the source size in the later phase.A peak of one-directional intensity distribution at 35 GHz always lies on the core of the hard X-ray source, showing a shift of the position synchronous with the hard X-ray core. This may imply a common source for the radio waves and the hard X-rays.The source of the thermal component observed at the soft X-rays (7–14 keV) after the early phase covers a whole H patches. This may imply a physical relation between the thermal X-ray loops and the H brightening. 相似文献
3.
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
4.
S. Hayakawa T. Kato F. Makino H. Ogawa Y. Tanaka K. Yamashita M. Matsuoka S. Miyamoto M. Oda Y. Ogawara 《Astrophysics and Space Science》1971,12(1):104-117
Cosmic soft X-rays in the energy range between 0.14 and 7 keV were observed with thin polypropylene window proportional counters on board a sounding rocket. The field of view crossed the galactic plane in the Cygnus-Cassiopeia region at a large angle and reached the galactic latitudes of –55° and +30°. Referring also to the result with Be window counters, we obtained the energy spectrum of Cyg XR-2, the flux from the Cas A region and the distribution of the intensity of diffuse X-rays over the scanned region. The turn-over of the Cyg XR-2 spectrum at about 1 keV indicates that the distance of the Cyg XR-2 source lies between 600 and 800 pc, if the turn-over is due entirely to interstellar absorption. The flux from the Cas A region is obtained as 0.23±0.05 photons cm–2 sec–1 in the energy range between 1.1 and 4.1 keV. The intensity of diffuse soft X-rays depends on the galactic latitude more weakly than expected from the interstellar absorption of extragalactic X-rays and shows asymmetry with respect to the galactic equator, thus suggesting a contribution of galactic X-rays. The spectrum of extragalactic X-rays is approximately represented by a power lawE
–1.8. 相似文献
5.
A new model for the source distribution of galactic soft X-ray (B and C band) emission is presented. From the mean dependence of count rates on galactic latitudeb (i.e., the brightness distribution), we derive the soft X-ray source functionQ as function of the optical depth by solving the equation of radiative transfer with the aid of a Laplace transform. Contrary to older Heaviside step models,Q is found to increase strongly, but not abruptly, in the range 1.5<<2.5, indicating a noticeable emission of X-rays from beyond theHi scale height. Using standard X-ray absorption cross-sections for the interstellar medium, we find that the B band X-ray emission coefficient is non-zero within theHi disk and has a maximum at az-value slightly above the Hi scale height. In the C band, the emission coefficient slightly decreases with increasingz, at least up to theHi scale height. A non-zero source function near the galactic plane implies that the interstellar medium (ISM) within theHi scale height is not only an absorbing layer but is mixed with X-ray emitting regions. The so-called local hot bubble is adopted as one of these regions. The maximum of the B band emission coefficient, together with the sharp increase ofQ, is strong evidence for the existence of a galactic soft X-ray halo, and, moreover, give rise to the assumption of a general intergalactic X-ray background. The effective absorption cross-sections given in the literature, based on an (pure) exponential dependence in the negative correlation between count rates andHi column densities, were biased to be too small, in particular in the B band. In replacing the Heaviside step (in the ISM) by a smoothed transition region, these inconsistencies become spurious. 相似文献
6.
In accordance with the data on the Faraday rotation, angular coordinates, and dispersion measurements and distances of 38 pulsars, the strengthB=2.1±1.1 G and directionl=99°±24°,b0° of the large-scale galactic magnetic field and the mean electron density in the galactic discN
e=0.03±0.01 cm–3 are determined. A comparison with the results of a study of the measures of rotation of extragalactic radio sources enabled us to estimate the characteristic half-width of the distribution of the electron density on the Z-coordinate (h400 ps). The characteristic size of galactic magnetic field flucturations is shown to be =100–150 ps. 相似文献
7.
Wolfgang Kundt 《Astrophysics and Space Science》1987,129(1):195-201
A re-interpretation is offered for both the galactic center lobe and the high-velocity clouds in the galactic halo: the galactic center lobe is a 2-sided chimney for relativistic pair plasma emerging from the center of the Milky Way (=Sag A*) and streaming as 2 jets through the halo. The channel walls of the flow serve as cold traps for the galactic fountain whenceHi clouds rain back into the disk. 相似文献
8.
A coronal hole was observed at 85 GHz(3.5 mm-) on November 24, 1970, when a spectacular coronal hole was observed in soft X-rays by AS&E. The millimeter counterpart of the hole is much weaker and less widespread than in X-rays. The brightness temperature inside the hole was in most places about 100–200 K lower than the mean brightness temperature of the Sun at 85 GHz. 相似文献
9.
J. M. McCanney 《Astrophysics and Space Science》1981,74(1):57-64
A new theory for galactic arm formation shows the arms to be continually eminating from the galactic nucleus due to a continual influx of cosmic dust. In the neighborhood of the nucleus the problem is treated as a fluid flow and a simple solution is given using conservation of momentum. When rotational dynamics are included the spinning arm system is the result. This solution resolves the problem of the missing mass, accounts for warped disk galaxies and gives a probable source for the gravity waves measured by Weber which eminate from our galactic center. Reversal of arm direction is demonstrated and examples of such reversals are cited. An approximate theoretical estimate of the age of our Sun is found to be in good agreement with radio isotope dating. A general result shows why twin star systems are in such great abundance in a galaxy. It gives a model of galactic evolution which begins with only a single massive nucleus with the collapsing gas clouds forming the arms. 相似文献
10.
We simulated collisions of High Velocity Clouds with the galactic disk with a simple hydrodynamical code. Main aspects of the morphology of nearby (d < 500 pc) cloud complexes, like the Oph, Orion and Taurus-Auriga-Perseus complexes, are reproduced. These aspects include total mass, distance from the galactic plane, orientation of elongated gas structures with respect to the plane, and relative position of clusters of O-B stars with respect to the main concentrations of molecular gas. The space distribution of stars of different ages, usually explained in terms of sequential star formation, is interpreted in a new way in our model. 相似文献
11.
Martin Beech 《Astrophysics and Space Science》1987,138(1):113-119
In this article it is argued that galactic magnetic fields are generated in the earliest moments of galaxy collapse. Our model proposes that provided, even if only briefly, a supermassive star is formed early on in the galaxy formation process, this star can produce a strong centrally localized magnetic field which may act as the seed field from which a galactic field can grow. In order to substantiate this model, detailed numerical calculations will be required. 相似文献
12.
The surface distribution of M stars is studied by differentiating them according to whether they show a circumstellar dust shell (CS) or not. Analysis shows that galactic latitudinal and longitudinal distributions are not determined by spectral subclasses alone. The study also indicates that M-type stars with CS have higher luminosities in the K band than those without CS. The M stars used in the study are obtained from theTwo-Micron Sky-Survey Catalogue (IRC) which is a most unbiased sample with respect to the interstellar extinction. The CS feature is identified by the ratio of flux densities at 12 and 25 m in the IRAS point source catalog. 相似文献
13.
On 23 May 1967 energetic (10–50 keV) solar flare X-rays were observed by the OGO-III ion chamber during the period 1808–2100 UT. The time-intensity profile for the X-ray event showed three distinct peaks at 1810, 1841 and 1942 UT. The second peak, which is equivalent to 2.9 × 10–3 ergs cm–2sec–1 above 20 keV, is the largest X-ray burst observed so far by the OGO-I and OGO-III ion chambers. The soft (2–12 Å) X-ray observations reported by Van Allen (1968) also show similar peaks, roughly proportional in magnitude to the energetic X-ray peaks. However, the intensity of energetic X-rays peaked in each case 5–10 min earlier than the soft X-ray intensity indicating a relatively hard photon energy spectrum near the peak of the energetic X-ray emission. The corresponding time-intensity profile for the solar radio emission also showed three peaks in the microwave region nearly coincident with the energetic X-ray peaks. The third radio peak was relatively rich in the metric emission. Beyond this peak both the energetic X-rays and the microwave emission decayed with a time constant of 8 min while the corresponding time constant for the soft X-rays was 43 min. In view of the earlier findings about the energetic X-rays it is indicated that the 23 May solar X-ray event was similar to those observed earlier. During the 23 May event the integral energy flux spectrum at the time of peak intensity is found to be consistent with the form e
–E/E
0, E
0 being about 3.4 and 3.7 keV for the peaks at 1841 and 1942 UT, respectively. Assumption of a similar spectrum during the decay phase indicates that the spectral index E
0 decreased nearly exponentially with time.The OGO-III ion chamber, which is also sensitive to protons 12 MeV, observed a solar particle event starting at 2100 UT on 23 May. It could not be determined uniquely which of the two principal X-ray peaks was associated with the particle event, and in fact both may have contributed. The particle intensity reached its maximum value at 1003 UT on 25 May 1967. The equivalent peak radiation dosage was 24 R/hour behind the 0.22 g cm–2 thick aluminum wall of the chamber. This peak radiation dosage was considerably smaller than the maximum dosage (60 R/hour) during the 2 September 1966 solar particle event, the largest event observed so far by the OGO-I and OGO-III satellites. The temporal relationship between the solar X-ray and particle events on 23 May 1967 was similar to that observed in the solar flare events on 7 July 1966, 28 August 1966 and 27 February 1967. 相似文献
14.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1985,35(1):23-43
It is shown that with a virial approach to the solution of the many-body problem the integral characteristics of a system (Jacobi's function and total energy), being present in Jacobi's equation, are immanent to its own integrals. Estimating the Lyapunov stability of motion of a system they play the role of Lyapunov functions.Studying Lyapunov stability of the virial oscillations of celestial bodies we used the Duboshin criterion applicable when permanent perturbations are present. In the case of conservative systems the potential energy of the system plays the role of such a perturbation. Thus, the nature of the virial oscillations can be understood as an effect of non-linear resonance between the kinetic and the potential energies.It is shown that the stability of virial oscillations of conservative systems relative to variations of the form-factors product is only a necessary condition in the proof of the hypothesis that =const. for celestial bodies. The sufficient condition for the proof of this equality consists of the given direct derivation of the equation of virial oscillations of celestial bodies from Einstein's equation, as well as of the equivalence of Schwarzschild's solution and the solution of Jacobi's equation at
.The stability of virial oscillations for dissipative systems is studied. It is shown that the stability is limited by the period of time of its bifurcation. 相似文献
15.
A. J. Owens 《Astrophysics and Space Science》1976,40(2):357-367
The general solution for the distribution of ages for primary galactic cosmic rays is given for a class of steady-state, bounded models of cosmic-ray diffusion in the Galaxy. Both one-and threedimensional models are considered, with point sources and distributed sources. In all models, the age distribution, is approximately exponential for ages longer than the average age, although for shorter ages the distribution depends on the details of the model. The leaky-box model, with an exponential age distribution, is thus a good approximation to most diffusive models. It is shown that one-dimensional (disk) models are consistent with both age and anisotropy data for galactic cosmic rays regardless of whether production takes place near the galactic center or throughout the disk. 相似文献
16.
A study of the galactic structure has been made by deriving the brightness distribution of the galactic plane at 2.2 m and 4.2 m near infrared region using infrared objects detected by ground-based sky surveys. The infrared brightness distribution shows distinct peaks at every 8–12° galactic longitude and indicates a periodic structure. The one-to-one positional correlation observed between the periodic structure in 2.2 m infrared brightness and the 2.6 mm CO emission line suggests that the near-infrared sources are strongly associated with dense clouds of molecular hydrogen distributed in the galactic plane. 相似文献
17.
We argue that a combined evidence from galactic and extragalactic studies suggests that a major star formation in giant galaxies is preceded by an evolutionary phase at which a strong galactic wind driven by the initial burst of star formation enriches the gaseous protogalaxy with metals and heats it up, so that the latter turns over from contraction to expansion. The result is the ejection of enriched material from the outer part of the protogalaxy into the intergalactic space, while the inner part, after a delay of about one to a few Gyr, finally contracts and cools down to form the galactic major stellar component (the hot model of galaxy formation). The paper presents a specific mechanism to produce a hot protogalaxy according to which an early galactic wind is imparting energy and momentum into a collapsing protogalaxy whose mass is contained mainly in clouds and only a small portion is in the intercloud gas that provides pressure confinement for the clouds. The model is then capable of accounting for the nearly equal mass and iron abundance in cluster giant galaxies and the intracluster gas provided the observationally plausible input parameters for giant galaxies and early galactic winds are adopted. It also predicts the formation of long-lived X-ray coronae with characteristics similar to those observed around giant ellipticals.The model specifies a characteristic length-scale that can be very naturally interpreted as a size for a stellar system to come; a very encouraging result is that it perfectly fits in with a typical size of giant ellipticals. 相似文献
18.
F. W. Stecker 《Astrophysics and Space Science》1969,3(4):579-599
A general formula is derived for calculating the -ray spectrum resulting from the annihilation of cosmic-ray positrons. This formula is used to calculate annihilation--ray spectra from various equilibrium spectra of secondary galactic positrons. These spectra are then compared with the -ray spectra produced by other astrophysical processes.Particular attention is paid to the form of the -ray spectrum resulting from the annihilation of positrons having kinetic energies below 5 keV. It is found that for mean leakage times out of the galaxy of less than 400 million years, most of the positrons annihilating near rest come from the -decay of unstable nuclei produced in cosmic-ray p-C12, p-N14, and p-O16 interactions, rather than from pi-meson decay. It is further found that the large majority of these positrons will annihilate from an S state of positronium and that 3/4 of these will produce a three-photon annihilation continuum rather than the two-photon line spectrum at 0.51 MeV. The results of numerical calculations of the -ray fluxes from these processes are given. It is concluded that annihilation -rays from the galactic halo may remain forever masked by a metagalactic continuum. However, an 0.51 MeV line from the disk may well be detectable. It is most reasonable to assume that this line is formed predominantly by the annihilation of the CNO -decay positrons. Under this assumption, the intensity of the line becomes a sensitive measure of the galactic cosmic-ray flux below 1000 MeV/nucleon. 相似文献
19.
Sh. T. Habibullin 《Earth, Moon, and Planets》1992,58(1):79-95
The method of estimation of the limits, containing the equator inclination of a celestial body, had been developed. In this method it is necessary to know the orbital elements and the mass of a celestial body. Another condition is that the axial rotation of a body should be in the resonance with its orbital motion. It has been found that the equator inclinations should have the values between 1 .7 and 2 .6 for Mercury and between 1 .0 and 1 .8 for the Moon. It also has been found that largest harmonics in Mercury's physical libration are the harmonics sin( – 3g), cos( – 3g), sin g and sin 2. 相似文献
20.
The critical accretion flow of gas onto compact stars with mass of 0.6M
is investigated by numerical integrations of the time-dependent hydrodynamic equations in the sphericallysymmetric and optically thick case. For the compact stars surrounded by such a dense cloud of gas, the radiation pressure force decelerates the infall gas significantly and free fall regime of the gas is not at all attained. This results in incident low velocities at the standing shock front close to the stellar surface, low temperatures of the gas around the compact stars, and no X-ray in white dwarfs but soft X-rays in neutron stars, respectively. Some applications of the results to the X-ray sources are discussed. 相似文献