The optical continuum of solar and stellar flares     

M. A. Livshits  O. G. Badalyan  A. G. Kosovichev  M. M. Katsova 《Solar physics》1981,73(2):269-288

A further development of the Kostyuk-Pikelner's model is presented. The response of the chromosphere heated by non-thermal electrons of the power-law energy spectrum has been studied on the basis of the numerical solution of the one-dimensional time-dependent equations of gravitational gas dynamics. The ionization and energy loss for the emissions in the Lyman and Balmer lines have been determined separately for the optically thin and thick L-line layers. Due to the initial heating, a higher-pressure region is formed. From this region, disturbances propagate upwards (a shock wave with a velocity of more than 1000 km s^-1) and downwards. A temperature jump propagates downwards, and a shock is formed in front of the thermal wave. During a period of several seconds after the beginning of this process, the temperature jump intensifies the downward shock wave and the large radiative loss gives rise to the high density jump ( ₂/ ₁ 100). The numerical solution has been analyzed in detail for the case heating of the ionized and neutral plasma, and a value of this heating is close to the upper limit of the admissible values. In this case, the condensation located between the temperature jump and the shock wave front, may emit in the observed optical continuum.In their essential features, the gas dynamic processes during the flares in red dwarf atmospheres are the same as those in the solar atmosphere. However, the high atmospheric densities, smaller height scale in red dwarf atmospheres, and greater energy of this processes in stellar flares, give rise, in practice, to the regular generation of optical continuum. The photometric parameters of a source with n 0¹⁵ cm^-3, T 9000 K, and _z 10 km are in a good agreement with observations.  相似文献   

OSO-8 observations of CaII H and K,MgII h and k,Lα and Lβ above a sunspot     

F. Kneer  G. Scharmer  W. Mattig  A. Wyller  G. Artzner  P. Lemaire  J. C. Vial 《Solar physics》1981,69(2):289-300

Observations with the French (L.P.S.P.) experiment on board OSO-8 of a sunspot and nearby plage region are described. The behaviour of the emission cores of the Ca II H and K and Mg II h and k resonance lines is very similar and the correspondence in intensity between the four lines persists in all observed features. In contrast, the Lyman lines show little correlation with the other lines. Their emission regions appear broader in the spectroheliograms than the underlying sunspot structure and must not necessarily possess a counterpart in lower layers. From the central intensity of L above the umbra an electron density of 4.3 × 10¹⁰ cm^-3 n _e ^* 2.3 × 10¹¹ cm^-3 at 20 000 K is estimated.Mitteilungen aus dem Kiepenheuer-Institut Nr. 186.Stockholm Observatorium, S-13300 Saltsjöbaden, Sweden.Laboratoire de Physique Stellaire et Planétaire, CNRS, P.O. Box 10, F-91370 Verrières-le-Buisson, France.  相似文献   

X-ray of gamma-ray bursts observable by HEAO-B     

I. G. Mitrofanov 《Astrophysics and Space Science》1981,80(2):303-306

On grounds of Mazetset al. (1980a) conclusion that all gamma-ray bursts recorded were emitted at the distance 1 kpc from the Sun it is shown that bursts from the Galaxy and from another galaxies may be observable byEinstein Observatory (HEAO-B). The HEAO-B observing programs are considered and the numbers of possibly recorded events are estimated. It is concluded that the important information about sources of gamma-bursts may be obtained in this way.  相似文献   

The distribution of infrared sources in the galactic plane     

A. G. Ananth  B. V. Nagaraja 《Astrophysics and Space Science》1981,77(2):503-509

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   

The radiative relaxation time in the chromosphere     

R. G. Giovanelli 《Solar physics》1978,59(2):293-311

The cooling effect of emission in the spectral lines, which dominates over continuous emission in the chromosphere and becomes important first around the temperature minimum, modifies greatly the radiative relaxation timet _r in the solar atmosphere. This rises from low photospheric values to a maximum of 8 min just aboveT _min, falls in the low chromosphere to 1.5 min because of line emission, but rises again to 6 min atT 7000–8400 K in the chromosphere where hydrogen ionization increases the specific heat.  相似文献   

Editorial     

A. G. W. Cameron  Z. Kopal  C. P. Sonett 《Earth, Moon, and Planets》1978,18(1):3-3

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Commuting in the USSR and related research     

Khorev BS  Smolina TK  Vishnevskiy AG 《Soviet geography》1978,19(6):373-378

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The evolution of the crystalline rocks | K. Bailey and R. Macdonald (editors), 1976. Academic Press,London, 484 pp., £ 16.00     

W.G. Ernst 《Earth》1978,14(1):79-80

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Analysis of stellar occultation data: Effects of photon noise and initial conditions     

R.G. French  J.L. Elliot  P.J. Gierasch 《Icarus》1978,33(1):186-202

A new inversion technique for obtaining temperature, pressure, and number density profiles of a planetary atmosphere from an occultation light curve is described. This technique employs an improved boundary condition to begin the numerical inversion and permits the computation of errors in the profiles caused by photon noise in the light curve. We present our assumptions about the atmosphere, optics, and noise and develop the equations for temperature, pressure, and number density and their associated errors. By inverting in equal increments of altitude, Δh, rather than in equal increments of time, Δt, the inversion need not be halted at the first negative point on the light curve as required by previous methods. The importance of the boundary condition is stressed, and a new initial condition is given. Numerical results are presented for the special case of inversion of a noisy isothermal light curve. From these results, simple relations are developed which can be used to predict the noise quality of an occultation. It is found that fractional errors in temperature profiles are comparable to those of pressure and number density profiles. An example of the inversion method is shown. Finally, we discuss the validity of our assumptions. In an appendix we demonstrate that minimum fractional errors in scale height determined from the inversion are comparable to those from an isothermal fit to a noisy isothermal light curve.  相似文献   

The magnetic-binaries problem: Motion of a charged particle in the region of a magnetic-binary system     

A. G. Mavraganis 《Astrophysics and Space Science》1978,54(2):305-313

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