The solar continuum from 900 to 130 000 Å and the photospheric temperature model

In order to obtain a better agreement between observed and computed values of the solar intensity, an improved temperature distribution is deduced for the range 0.02<0< 10. The intensity observations here considered refer to the wavelength region between 1980 and 129 500, and the center-limb variations generally go down to cos = 0.1. The improved model, given in Figure 4 and Table II, differs rather little from the Utrecht 1964 model, used here as a reference.It appears necessary to introduce an empirical correction function to be applied to the continuous absorption coefficient. This function was derived for the spectral region between 2000 and 130000 Å; it is shown in Figure 5.Furthermore, an extension of the model (1.10^–7<0< 2.10^–2) is deduced (see Table III and Figure 8), which reasonably well represents the observations of the ultraviolet solar flux ( 900–1700 Å).     

On the relationships between sfe (crochet) and solar X-ray and microwave bursts

Geomagnetic crochets (sfe) observed at Kodaikanal over the period 1966–71 have been studied in relation to solar X-ray bursts observed by NRL satellite (SOLRAD-9) in the 0.5–3 Å, 1–8 Å and 8–20 Å bands and radio bursts observed in the frequency range 1000–17000 MHz. The amplitude of sfe is linearly correlated with the peak intensities of X-ray bursts in the 1–8 Å and 8–20 Å bands. The single frequency correlation of sfe with radio bursts is a flat maximum in the frequency range 2000–3750 MHz. Following the spectral classification of AFCRL for microwave bursts, it is noticed that sfe are mostly associated with the A type burst spectra and are very poorly correlated with bursts with the G, C and M type spectra. These features differ from those of other SID's reported earlier.     

Сопоставление модели карлсона с моделью сплошной среды

, (1962, 1963) . , (1) (2) .     

Flare-related changes in the profiles of six photospheric spectral lines

The profiles of six photospheric absorption spectral lines (Fei 5250 Å, Fei 5324 Å, Fei 5576 Å, Cai 5590 Å, Cai 6103 Å and Fei 6165 Å), measured in the kernel of a 2N solar flare and in a quiet-Sun area, were compared. The observations were carried out with an echelle spectrograph of the Crimean Astrophysical Observatory. It was shown that, compared to the quiet-Sun profiles, the flare profiles are shallower in the line core and are less steep in the wings. Therefore, measurements of the longitudinal magnetic field made with a magnetograph system which uses the Cai 6103 Å  spectral line, can be underestimated by 18–25% in areas of bright H ribbons of a moderate solar flare. Modeling of the solar photosphere performed by using a synthesis method showed that, in a solar flare, the enhanced core emission seems to be related to heating of the photosphere by the flare, whereas the decrease of the slope of the wings was presumably caused by the inhomogeneity of the photospheric magnetic field.     

The solar-flare infrared continuum: Observational techniques and upper limits

Exploratory observations at 20 and 350 have determined detection thresholds for solar flares in these wavelengths. In the 20 range solar atmospheric fluctuations (the temperature field) set the basic limits on flare detectability at 5K; at 350 the extinction in the Earth's atmosphere provides the basic limitation of 30K. These thresholds are low enough for the successful detection of several infrared-emitting components of large flares. Limited observing time and lack of solar activity have prevented observations of large flares up to the present, but the techniques promise to be extremely useful in the future.The upper limits obtained thus far, for subflares, indicate that the thickness of the H flare region does not exceed 10 km. This result confirms the conclusion of Suemoto and Hiei (1959) regarding the small effective thickness of the H-emitting regions in solar flares.     

A UV spectral atlas of a prominence

The ultraviolet spectrum of a large prominence has been observed with the High Resolution Telescope and Spectrograph (HRTS) on SPACELAB 2, 5 August, 1985. The spectrum covers the wavelength range 1335–1670 Å and shows numerous emission lines from gas at chromospheric and transition region temperatures. An Atlas of the prominence spectrum has been made showing absolute calibrated intensities on an accurate wavelength scale. The Atlas includes for comparison the corresponding UV-spectrum from an average quiet solar region.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Околозвездные оБлака по данным 2800 Mgii

2800 Mgii (. 1). (N ⁺/N ₁1000) , , (N ⁺/N ₁10). , . —, , . — . : ; 0.002 1 , 0.1 ; () 100 ^–3; ; ; , 10 ; 10^–4 1 . 2800 Mgii .     

Формирование Универсальных и Диффузионных Участков Нелинйных Спектров Релятивистских Электронов В Пространственно Ограниченных Источниках

, () , , ( =2) , . (, , ). ( =0,5) .     

Структура и эволюция Сверхмассивных вращающихся магнитных политроп

. - . . , . - . - , , , -. ., , .

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The structure of rotating magnetic polytropes is considered in Roche approximation. Investigation of the influence of poloidal as well as toroidal magnetic fields on the conditions of the beginning of matter outflow due to rotational instability is carried out. The influence of the turbulent convection and twisting of magnetic force-lines on the time of smoothing of differential rotation is considered. The estimate of the magneto-turbulence energy generated by differential rotation is presented. Both maximum possible energy output and duration of the quasi-statical evolution phase up to the appearance of hydrodynamic instability due to the effects of general relativity are calculated for supermassive magnetic polytropes of index three with uniform or differential rotation. The radius-mass relation is obtained for supermassive differentially-rotating magnetic polytropes referring to the longest part of the quasi-statistical evolution stage; some consequences are pointed out, including the period-luminosity relation.The evolution of the considered models of supermassive rotating magnetic polytropes with different character of rotation and different geometry of a magnetic field is discussed.The results obtained are summarized in the last section.

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English translation will appear in the next issue ofAstrophys. Space Sci.

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Receipt delayed by postal strike in Great Britain     

ОJ 287: Поляризационное и фотометрическое поведение В 1971–1976 гг

J 287 1972–1976. , . . J ( ), () . (₀=80°) . J 287 ¶ . p=42.8%, ₀=101°. (50%).     

Comments on filament-disintegration and its relation to other aspects of solar activity

Studies of disparitions brusques in solar cycles 19 and 20 (to 1969) indicate that such events occur frequently. Approximately 30% of all large filaments in these cycles disintegrated in the course of their transit across the solar disk. Major flares occurred with above average frequency on the last day on which 141 large disappearing filaments were observed (1958–60; 1966–69). Relationships between a disintegrating filament on July 10–11, 1959, a prior major flare, a newly formed spot, and concomitant growth of H plage are presented. Observation of prior descending prominence material apparently directed towards the location of the flare of 1959 July 15^d19^h23^m is reported. The development of the filament-associated flare of February 13, 1967 is described.Visiting Astronomer, McMath-Hulbert Observatory.     

Some studies on Hα-flares and microwave bursts in relation to sunspot magnetic configurations

Sunspot associated H-flares and microwave bursts occurring during the period 1972 to 1974 have been examined in relation to the magnetic strength and configurations of the sunspots and sunspot groups (abbreviated as spots). Important results obtained are: (i) percentage occurrences of flares exceeds those of microwave bursts up to a magnetic field strength of 2000 G while the reverse is true for higher field strength of spots, (ii) flare productivity (average number of flares per spot) and also burst productivity are comparatively higher in the case of and types of spots than in the case of other types of spots, (iii) the above productivities are predominantly high when magnetic configuration of spots changes during their life time, and (iv) impulsive type of microwave bursts are more associated with spots having changing type of magnetic configuration.     

Theoretical model of flares and prominences

A theoretical model of flare which explains observed quantities in H, EUV, soft X-ray and flare-associated solar wind is presented. It is assumed that large mass observed in the soft X-ray flare and the solar wind comes from the chromosphere by the process like evaporation while flare is in progress. From mass and pressure balance in the chromosphere and the corona, the high temperature in the soft X-ray flare is shown to be attained by the larger mass loss to the solar wind compared with the mass remained in the corona, in accord with observations. The total energy of 10³² erg, the electron density of 10^13.5 cm^–3 in H flare, the temperature of the X-ray flare of 10^7.3K and the time to attain maximum H brightness (600 s) are derived consistent with observations. It is shown that the top height of the H flare is located about 1000 km lower than that of the active chromosphere because of evaporation. So-called limb flares are assigned to either post-flare loops, surges or rising prominences.The observed small thickness of the H flare is interpreted by free streaming and/or heat conduction. Applications are suggested to explain the maximum temperature of a coronal condensation and the formation of quiescent prominences.     

Исследование устойгивости периодигеских движений в окрестности коллинеарных точек либрации

1937 - (, 1938). , , , , . , . . (, 1938), , . - (, 1938; Szebehely, 1967)., , . . - (, 1938), . — — . , , . , . . , . , , . . (, 1944). , .

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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.

     

Об устойчивости лагранжевых решений пространственной эллиптической задачи трех тел

. . ,e, , . . e, . , .

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Stability of the librational triangular points of the three-dimensional elliptic restricted three-body problem is studied. The problem is solved in the non-linear statement at the small values of eccentricity.For all values ofe, , besides ones which correspond to the resonances of the third and the fourth order the librational points are stable taking into account the terms up to the fourth order in the normal form of the Hamiltonian function of the perturbed motion.At sufficiently smalle and the non-stability in sense of Liapunov has been proved. The approximate equations of the boundary of the stability area in the planee, has been obtained. The cause of the non-stability is an equality of the rotational period of the principal attracting masses in the elliptic orbit and the period of oscillation of indefinitely small mass along the direction perpendicular to the plane of their motion.

     

Solar soft X-rays and solar activity

Soft solar X-rays (8 gl 12 Å) were observed from OSO-III. An analysis of the X-ray enhancements associated with 165 solar flares revealed that there is a tendency for a weak soft X-ray enhancement to precede the cm- burst and H flare. The peak soft X-ray flux follows the cm- peak by about 4 min, on the average. Additionally, it was found that flare-rich active centers tend to produce flares which are stronger X-ray and cm- emitters than are flares which take place in flare-poor active centers.     

The radio radius of the Sun at millimeter and centimeter wavelengths

The radio radius of the Sun is determined from an analysis of the radio contact times of the 7 March, 1970 and 10 July, 1972 solar eclipses from = 3 mm to = 31 cm. Agreement with other eclipse measurements is good. A best fit curve through the several points gives the radio radius to within approximately ±0.01 of the photosheric radius below -5 cm.     

Thermal runaway as the solar flare trigger mechanism

It is postulated that the solar flare trigger mechanism is a thermal runaway which occurs in the inner corona. This runaway is the result of a radiative power function which decreases with increasing temperature. Relationships of the onsets of H flares, hard X-ray, soft X-ray and centimeter radio bursts are consistent with the model. Flares are shown to be common solar phenomena which occur preferentially in hot and dense active regions.     

Periodic orbits of stars in axisymmetrical stellar systems

Periodic orbits of stars in axisymmetrical nearly spherical stellar systems have been investigated. Generating orbits have been found among periodic ones relating to the spherically-symmetrical field. The linear approximation appears to be insufficient for constructing periodic trajectories. Possible variants of the generating periodic solutions have been found, which give rise to disturbed periodic orbits in the second approximation.

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, . - . , . , .

     

Isophotal photometry and morphological changes in the flares

We report measurements made on the brightness in H of all parts of the flare photographed through a birefringent filter centered on H, using a scanning isodensitometer. From obtained isophotes of the flares we derived some information on the morphological changes in the flare and estimated the total energy in H of the flare.