A deeply embedded companion to LKHα198

The region around the Herbig Ae/Be star LkH198 was imaged at 10m with the CAMIRAS camera at the Canada-France-Hawaii Telescope and the Nordic Optical Telescope. We discovered a deeply embedded companion 6 north of LkH198, which may be responsible for most of the far-infrared emission in the region and for driving the molecular flow. LkH198 appears point-like at our resolution (FWHM 1.3), excluding an extended envelope of transiently heated small grains as the dominant origin of the mid-infrared excess in that star.     

A multibeam antenna for solar MM-wave burst observations with high spatial and temporal resolution

In this paper a new method for the determination of the position of microwave burst sources on the Sun, its implementation and first observational results, are presented. The 13.7 m antenna at Itapetinga with a five-channel receiver operating at 48 GHz and with a time resolution of 1 ms is used. Five horn antennas clustered around the focus of the Cassegrain reflector provide 5 beams diverging by about 2. This configuration allows the observation of different parts of an active region and the determination of the center of the burst position with an accuracy of 5 to 20 depending on the angular distance relative to the antenna axis. The field of view is 2 by 4. The time resolution of 1 ms is suitable to search for fast structures at 48 GHz. A total bandwidth of 400 MHz is used in order to achieve a sensitivity of 0.04 s.f.u. sufficient for the detection of weak bursts. First observational results of the flare on May 11, 1991 show a well-located source position during all stages.Paper presented at the 4th CESRA workshop in Ouranopolis (Greece) 1991.     

The Hard X-ray Imaging Spectrometer (HXIS)

The HXIS, a joint instrument of the Space Research Laboratory at Utrecht, The Netherlands, and the Department of Space Research of the University of Birmingham, U.K., images the Sun in hard X-rays: Six energy bands in energy range 3.5–30 keV, spatial resolution 8 over Ø 240 and 32 over Ø 624 field of view, and time resolution of 0.5–7 s depending on the mode of operation. By means of a flare flag it alerts all the other SMM instruments when a flare sets in and informs them about the location of the X-ray emission. The experiment should yield information about the position, extension and spectrum of the hard X-ray bursts in flares, their relation to the magnetic field structure and to the quasi-thermal soft X-rays, and about the characteristics and development of type IV electron clouds above flare regions.     

О природе квазаров и активных ядер галактик

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, 40 48 MAC (, 1976).     

The solar minimum temperature determined by the CO (A 1Π-X 1Σ)

The synthetic Voigt profile of the following transitions (v=0,v=0), (v=0,v=1), (v=1,v=1), (v=1,v=0) have been computed for different concentrations and temperatures of CO and compaed to the measured intensities of the UV sunspot spectrum by a high resolution spectrograph. From this comparison the solar minimum temperature has been determined.     

Photospheric and Chromospheric Activity Associated with 3B Flare of February 27, 1992

We have analyzed the H filtergrams and vector magnetograms of the active region NOAA 7070, in which a 3B/X3.3 flare occurred on February 27, 1992. The average area per sunspot of this active region was in declining phase at the time of the flare. The vector magnetograms indicate that the magnetic field was non-potential at the flaring site. Besides non-potentiality, the longitudinal field gradient was found to be the highest at the region showing initial H brightening. Further, in H filtergrams no appreciable change in the morphology of the filament tracing the magnetic neutral line was noticed in the post-flare stage. Also, the photospheric vector magnetograms show considerable shear in post-flare magnetic field of the active region. In this paper we present the observations and discuss the possible mechanism responsible for the 3B/X3.3 flare.     

Поле излучения в полубесконечной атмосфере, содержащей источники энергии

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Stability of the libration points of a rotating triaxial ellipsoid

The problem of stability of the equilibrium points (the libration points) in the problem of motion of a mass point in the neighbourhood of a rotating triaxial ellipsoid is investigated in the strict sense.In the plane of parameters, depending on the form and dynamical characteristics of the ellipsoids, the regions of stability and instability of the libration points are obtained.It is shown that the libration points of the ellipsoids, the form and dynamical characteristics of which are close to the planets of the solar system, are stable.

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Corrections to the lunisolar precession and the motion of the equinox from proper motions of Cepheids

Corrections to Newcomb's lunisolar precession and to motion of the equinox are evaluated from proper motions of 77 Cepheids, employing recently determined values of their distances. Results are diverse, depending on the weighting method. If the effect of the cosmic dispersion is neglected and ₀ is imposed to be 25 km/s/kpc, thenp ₁=1.1±0.2 and +e = 1.0 ± 0.1 per century in the FK4 system.Presented at IAU Colloquium No. 9, The IAU System of Astronomical Constants, Heidelberg, Germany, August 12–14, 1970.     

Adiabatic deceleration of secondary antiprotons in the envelopes of supernova exploding in dense clouds

Within the framework of the plasma-laser star model of quasars it is proposed that the quasar 0805+046 is a helium-rich shell star. (a) The strong emission line at 4712 Å is identified with Hei 4713. (b) The discontinuity in the continuous energy distribution at 3420 is identified with the helium discontinuity at 3422. (c) In the absorption-line spectrum many lines have been identified. It is shown that the proposed model provides a consistent and satisfactory interpretation of the observed spectra.     

Dimensional Analysis of the Flare Distribution Problem

Dimensional analysis is used to derive the distribution of solar flare energies,p() = A-^3/2, in accordance with recent observational and numerical results. Several other scalings, notably _fl ² , where _fl is the flare duration, are obtained as well.     

Heat flux saturation in hydrodynamic soft X-ray solar flare plasmas

The role of heat flux limitation in soft X-ray emitting solar flare plasmas is considered. Simple analytic arguments suggest that flux limitation is likely to be important during the explosive heating phase, even for relatively modest coronal energy fluxes (say 10⁹ erg cm^-2 s^-1). This conclusion is reinforced by a detailed flare loop simulation of the heating phase. Since flux saturation effectively bottles up the coronal heat flux, mass motions now assume a dominant role in transferring energy from the coronal flare source to the lower transition region. The mass-energy exchange between the corona and chromosphere produces dramatic changes in the thermal structure of the plasma which are reflected in the differential emission measure profile of the flaring loop.     

A new microwave/X-ray diagnostic for the thermal phase of solar flares

We have observed 10 solar bursts during the thermal phase using the Haystack radio telescope at 22 GHz. We show that these high frequency flux observations, when compared with soft X-ray band fluxes, give useful information about the temperature profile in the flare loops. The microwave and X-ray band fluxes provide determinations of the maximum loop temperature, the total emission measure, and the index of the differential emission measure (q(T)/T = cT^–1). The special case of an isothermal loop ( = ) has been considered previously by Thomas et al. (1985), and we confirm their diagnostic calculations for the GOES X-ray bands, but find that the flare loops we observed departed significantly from the isothermal regime. Our results ( = 1–3.5) imply that, during the late phases of flares, condensation cooling ( 3.5) competes with radiative cooling ( 1.5). Further, our results appear to be in good agreement with previous deductions from XUV rocket spectra ( 2–3).     

ANALYSIS OF 2D Hα SPECTRA AND MAGNETIC FIELD DURING THE IMPULSIVE PHASE OF A SOLAR FLARE

We obtained a set of well-observed 2D H spectral data of a 1N/M1.5 flare from the Solar Tower of Nanjing University. Using the H spectra, the sites of electron precipitation and high coronal pressure have been found, and the Doppler velocity was calculated from the red asymmetry of the H emission line by use of the bisector method. The current density distribution was also computed from magnetic field measurements. We have coaligned the H spectroheliograms and the magnetograms. It was found that the sites of electron precipitation were at the edge of a main current area. The sites of red asymmetry coincided with those of high coronal pressure. The flare reached its maximum in the magnetic shear region, though it began in a weak magnetic field. Several flare models are discussed to see which one could satisfy the observation.     

О лагранжевых и зйлеровых решеиях обощенной задачи трех тел

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This paper is a continuation and a generalization of one published earlier (Duboshin, 1969): it discusses the problem whether there exist the Lagrangian and the Eulerian solutions of the generalized three-body (material points) problem. Every point in this generalized problem acts on another, one with a force (attractive or repulsive) directed along the straight line passing through these points, and in an arbitrary manner depending on time, mutual distance and its derivatives, the first and the second. Here, generally speaking, the third axiom of dynamics (law of action and reaction) is not presupposed as fulfilled, that is, it is supposed that every two material points interact in a different way.This most general assumption being made, we establish the conditions which must dictate the laws of the interactions, so that the three points can always remain at the apexes of the equilateral triangle (Langrangian solution), or remain always on a straight line (Eulerian solution).The author believes that such general treatment of the three-body problem can be useful for theoretical studies in celestial mechanics and also for practical applications in the study of isolated stellar systems.

     

Observation of far ultraviolet radiation from early-type stars

Rocket-borne photon counters sensitive to bands 1060–1180, 1230–1350, and 1350–1480 were used to measure the celestial ultraviolet radiation above the terrestrial atmosphere. The energy spectra of six objects, Leo, CMa, Ori, , , Ori (combined), Ori, and Tau were obtained. The comparison of them with those calculated with the stellar model atmospheres indicates the deficiency of about 1 mag. in the ultraviolet region, when corrected for interstellar extinction, for all stars except Tau. The observed spectrum of Tau agreed with the theoretical one for normal interstellar extinction. The effects of line blanketing were examined for B1 and B2 stars, and found to account for a part of the difference between the observed and the theoretical values.     

Гидромагнитное Излучение Межпланетной Плазмы

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Interaction between the interstellar medium and solar wind plasma

The interaction processes governing the penetration of the interstellar gas into the solar neighbourhood are re-examined — as well as photo-ionization and charge-exchange processes, proton elastic collisions and electron ionizations help reduce the nearby gas densities. The total destruction rate varies little during the solar cycle, by perhaps 10%. Particle heating, particularly via the elastic collisions, determines the gas characteristics in the gravitationally focussed tail—enhanced H-density is prevented, while the He-tail is effectively hotter than 10³ K.Termination of the solar wind is rediscussed in the light of both electron heating and the stronger gas/plasma interaction. The spiral interplanetary field is taken to break up and the subsonic plasma flow to be controlled by the pressure of slowly cooling electrons. The terminating collisionless shock is then, if it exists at all, very weak (M ₁<1.4), subcritical, and energetically unimportant. Cosmic rays are little affected by this sonic transition, but at least the electron component should be modulated by plasma turbulence throughout the ionizing flow.

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Роль диффузного вешества В коронах галктик

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О колебаниях хвоста магнитосферы в приБлижении квазигидро динамики

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