The spectral indices in the optical continuum of the QSOs,BL Lacertae objects and the nuclei of Seyfert,N and normal galaxies

The hypothesis that the optical continua of QSOs, BL Lac objects and the nuclei of Seyfert, N and normal galaxies arise due to incoherent synchrotron radiation from electrons and consequently the flux of radiation in the optical continua of these objects is given by the power law:F(v)v is examined. Following Kinman, spectral indices _B–V and _U–B in(B-V) and(U-B) colours as well as their average and difference have been defined and calculated for samples of 227 QSOs, 32 BL Lac objects and nuclei of 62 Seyfert, 12 N and 7 normal galaxies. Here has been assumed to be an estimate of the spectral index . On the other hand, has been regarded as a measure of departure from the power law. On the basis of this, the distributions of and in QSOs, BL Lac objects and the nuclei of Seyfert, N and normal galaxies have been studied. The value of depends mainly on the balance of the energy loss due to synchrotron radiation and the rate of replenishment of energy by injection of high energy electrons in the radiating region. The increase in the value of and therefore that of indicates that the activity in the object is slowing down and the object is growing older. Assuming that the QSOs, BL Lac objects and the nuclei of Seyfert, N and normal galaxies essentially represent different phases in the evolutionary sequence of extragalactic objects, we suggest that they may be arranged in the sequence: QSOsBL Lac objects Seyferts 1N galaxies Seyferts 2 Normal galaxies in the decreasing order of activity in the core or nuclei of these objects.On leave of absence from the Government Science College, Rajpur, M.P., India.     

Theory of the Trojan asteroids

In the previously published Parts I and II of the paper, the author has constructed a formal long-periodic solution for the case of 11 resonance in the restricted problem of three bodies to 0(m ^3/2), wherem is the small mass parameter of the system. The time-dependencet(, ,m), where is the mean synodic longitude and is related to the Jacobi constant, has been expressed by ahyperelliptic integral. It is shown here that with the approximationm=0 in the integrand, the functiont(, , 0) can be expanded in a series involving standardelliptic functions. Then the problem of inversion can be formally solved, yielding the function (t, , 0).Similarly, the normalized period (,m) of the motion can be approximated by theHagihara hyperelliptic integral (, 0), corresponding tom=0. This integral is also expanded into elliptic functions. Asymptotic forms for (, 0) are derived for 0 and for 1, corresponding to the extreme members of thetadpole branch of the family of orbits.     

The photoionization mechanism of LINERs: stellar and nonstellar

We present high quality spectroscopic observations of a sample of 14 low ionization nuclear emission-line regions (LINERs). Starlight removal is achieved by the subtraction of a suitable absorption-line template galaxy, allowing accurate measurements of emission lines. We use these line fluxes to examine the possible excitation mechanisms of LINERs. We suggest that LINERs with weak [O I] 6300 emission ([O I]/H < 1/6) may beH II regions photoionized by unusually hot O-type stars. LINERs with [O I]/H < 1/6 may be powered by photoionization from a nonstellar continuum. This is supported by the detection of broad h emission, a correlation between line width and critical density, and point-like X-ray emission in several of these objects.     

The ionization mechanism in low level emission galaxy nuclei: Shocks

We analyze the emission component of galaxy nuclei at very low intensity levels (W(H)2Å). This emission level is considerably lower than that of classical LINERS like NGC 1052. We have access to weaker emission lines by averaging spectra with similar line ratios for H [NII], and [SII]. From the resulting spectrum for very low level emission nuclei, the [SII] 6717, 6731/[SIII] 9069, 9532 line ratio criterion (Diazet al., 1985a) unambiguously shows that shock-wave heating is the mechanism responsible for the ionization in such objects.     

The neutral interface adjoining theHII region DR21

Observations of C100 and C125 atomic carbon recombination lines were made at the Algonquin Radio Observatory, towards the neutral interface separating theHii region DR21 (at RA=20^h37^m14^s, Dec=+42°0900) from its associated molecular cloud. An analysis of the Cn observations in conjunction with a simple model of a neutral interface enabled the derivation of the following parameters: electron density of 300 cm^–3, electron temperature of 30 K, microturbulent velocity of 2.3 km s^–1, and depth of the neutral interface of 0.01 pc. A single,stimulated emission model is sufficient to reproduce the Cn observations in the wavelength range from 4.6 cm (C100) to 21 cm (C166). All the known Cn data do support a pressure equilibrium between the neutral interface and theHii region, after the usual allowance is made for carbon depletion on grains.     

A search for unique objects in nearby galaxies

A list of 171 stars in the galaxy M33 is presented. The stars could be considered as candidates for unique objects, such as SS 433, S Dor, P Cyg stars and possibly new kinds of peculiar objects. All these stars have been selected on the basis of the similarity to SS 433, free from interstellar absorption: OB star with strongH emission or with HeII 4686 and CIII, NIII 4630 - 4660 emission lines; a hot star inside a supernovae remnant or radio nebula. The variability of these stars has been used as an additional criterion of the selection. It is important to carry out spectral observations of the presented stars, which will allow us to select stars with intrinsicH emission.     

A study of the contrast of sunspots from photometric images

The thermal contrast , and the umbra-penumbraA _u/A _p, were calculated for 63 sunspots of various sizes and morphologies. Contrary to the assumptions of the PSI model, andA _u/A _p were found to be quite variable. The values of ranged from 0.1807 to 0.4266;A _u/A _p ranged from 0.0089 to 0.4899. The values of andA _u/A _p correlated well (r = 0.6018;p<0.005) and the regression for andA _u/A _p was obtained: = (0.220 ± 0.016) + (0.340 ± O.06)A _u/A _p. The values of andA _u/A _p were then compared with complexity ratings, magnetic field strength, time, and . The quantities andA _u/A _p were found to be independent of the complexity, magnetic field strength, and time factors. The correlation between andA _u/A _p lead to the proposed division of into an umbral thermal contrast _u, and a penumbral thermal contrast _p. These values were calculated from the photometric data: _u = 0.57 ± 0.01 and _p = 0.26 ± 0.006.     

Light-element abundances of peculiar a stars

Light-element abundances are compiled for six peculiar A stars (3 CenA, ² CVn, HR 1732,v For, Cnc, and 112 Her) with Heilines very weak for their colours. The abundances are interpreted on the theory that peculiar A stars were once secondaries in binary systems in which the primaries exploded as type II supernovae. During the explosions of the primaries, protons were accelerated to high energies (>20 MeV) in shock waves at the secondaries, and spallation of He, C, N, and O occurred. This was followed by the arrival of heavier elements from the primaries. Abundances on ² CVn, HR 1732, andv For were subsequently modified by surface nuclear reactions involving protons and -particles accelerated to lower energies (10 MeV), probably by magnetic fields. Successive (, ) reactions formed Si²⁸ from Ne²⁰, and (p, ) reactions acting on A⁴⁰ and Ca⁴⁰ may have contributed to the excesses of Cl observed on ² CVn and HR 1732. These proposals have interesting implications with regard to the relative abundances of the iron-peak elements found on peculiar A stars and in the Solar System.     

The Velocity Field and Kinematics of the Galaxy NGC 784 in the Hα Line

In this paper we present the H map, the 2D velocity field and the rotation curve of the galaxy NGC 784 obtained with the ByuFOSC2 scanning Fabry-Perot interferometer, attached at the prime focus of the 2.6-m telescope of Byurakan Observatory. The H image shows several HII condensations along the major axis of the galaxy. The galaxy has an asymmetric distribution of the H emission. The rotation curve is quite symmetric with a low gradient in the central part of the galaxy.     

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.     

Hα Emission Stars in the Cepheus OB3 Region

H emission objects were searched for, using the objective-prismSchmidt plates in a 36 deg² sky area covering the Cepheus OB3 association.Hundred and eight emission stars have been found, 68 of which are newfindings to our knowledge. The properties of the IRAS point sourcesidentified with H emission stars indicate that most of theH emission stars are T Tauri stars or related objects. Hemission stars associated with IRAS sources and those unassociated havedifferent distributions, suggesting an age sequence among them.Altogether, they show a ring- or shell-like surface distribution, whichalmost coincides with that of heated dusts, and these distributionsappear to be encompassed by an HI shell.     

Study of alpha component dynamics in the solar wind using the Prognoz satellite

The analysis of solar wind He⁺⁺ and H⁺ ion distribution functions, collected over five months by the satellite Prognoz 1, shows that these are in general maxwellian but that often tails appear at higher speeds. The existing relation V-T, the observation of ratios of T/Tp 3.83 and V/Vp 1.035 give evidence of preferential He⁺⁺ ion heating and acceleration. The criteria for heating by dissipation of hydromagnetic waves proposed by Barnes and Hung (1973) are tested experimentally. Finally, multifluid models are likely to predict certain observations such as dependence of the velocity ratio V/Vp on the solar wind flux.     

Late-time emission of the type II Supernovae powered by the radioactive decay56Ni−56Co−56Fe

A one-zone model for the late time SN II energized by the radioactive decay⁵⁶Ni–⁵⁶Co–⁵⁶Fe is presented. The model succeeds in reproducing for the late time evolution of H and [Oi] 6300 emission lines in SN1970g for the reasonable set of parameters: mass of ejecta 4M , boundary velocityv ₀=4000 km s^–1 and amount of⁵⁶NiM _Ni=0.02M . However, a one-zone model does not account for the late time continuum. In the case of SN1980k the radioactive model fits H and [Oi] 6300 emissions att250 day satisfactory but fails at very late time, e.g.,t=670 day when the predicted value of the ratioL(H)/L(6300) is two orders of magnitude smaller than the observed one. We suggest that the strong H emission in SN1980k on the 670th day is due to the interaction of the supernova envelope with the pre-SN wind. The radioactive model for the late time SN II predicts strong Mgii 2800 line and detectable Hei 10830 line in emission and absorption.     

Polarization of Lyman-alpha lines from hydrogen-like ions

The Oppenheimer-Penney theory to calculate the polarization of L lines from hydrogen-like ions, when the impact electrons are distributed such that their probability is more in the regions close to the magnetic field (f(cos ⁿ ), is applied by Chandra and Joshi (1984). The work of Chandra and Joshi (1984) has been reinvestigated for the pitch-angle distributionf()sin ⁿ . The degrees of polarization are still found to be independent of the atomic number of a hydrogen-like ion.     

Photometry and Spectrophotometry of the Seyfert Galaxy MRK 509 over 23 Years Photometry And Spectrophotometry Of The Seyfert Galaxy Mrk 509

In the time period from 1972-1993, the Seyfert 1 galaxy Mrk 509 showed large variations of its optical continuum and broad emission line fluxes. The broad H and H emission lines have approximately the same profiles, which retain their shape during flux variations. The relationship between the continuum and emission line fluxes varies with time. The spectral energy distribution of the variable continuum based on UBVRI data has the form lgF() lg, with the dereddened = -0.60.     

On the line intensity ratios E(Hα)/E(D3) and E(Hβ)/E(D3) in prominences

The intensity ratios E(H)/E(D3) and E(H)/E(D3) in prominences depend on the total optical thickness in H of the layer. The emission of the He D3 line appears relatively enhanced in thin layers and in outer parts of the prominences.     

A search for steep low-frequency radio spectra among quasars and clusters of galaxies

Using published flux densitiesS at low frequenciesv, radio spectra were constructed for 3C, 4C, and 4CT radio sources in Abell clusters of galaxies, radio galaxies outside Abell clusters, and quasars with known redshifts. About half the sources in rich Abell clusters (richness classesR>-2) have steep spectra between 38 and 178 MHz with spectral indices ₃₈ ¹⁷⁸ > whereSv ^–. However, radio galaxies outside clusters have values of ₃₈ ¹⁷⁸ 1.2, and no steep spectra were found among 170 quasars. The radio sources in rich clusters are probably confined by intergalactic gas, and the steep spectra develop over a period of 10⁹ yr as relativistic electrons lose energy. The absence of steep spectra among quasars does not necessarily mean that quasars never occur in rich clusters of galaxies, since quasars are probably being observed only in their early high-luminosity phases. The possibility that some quasar events occur in the nuclei of the dominant cD galaxies in clusters is discussed, but quasar events may occur in more than one type of galaxy.     

On the modeling of the three-fluid structure of the quiet solar wind

The reciprocal influence of the electrons and protons, on one side, and the -particles, on the other side in the quiet solar wind is investigated within the framework of a conductive three-fluid model (with frictional forces included). For this purpose two mathematical methods are used, namely: I. Simultaneous solution of the fluid equations for all three species; and II. Solution of two-fluid equations (for electrons and protons) followed by that of a modified one-fluid equation for the -particles (in which the two-fluid solutions are used for electrons and protons).The results of our investigation indicate the following: (a)The macroscopic -particle characteristics as obtained from the two methods of solution are almost identical. Thus, the differences between the three-fluid and two-fluid characteristics of the electrons and protons represent a second order (and negligible) effect on the -particle characteristics. In both approaches, the frictional interaction between -particles and protons raises the (lower) -particle streaming velocity to that of the protons and decreases the relative to proton density ratio to a value about 0.035, as observed at 1 AU, (b)The electron and proton characteristics obtained from three-fluid and two-fluid solutions are similar, except for the proton temperature. The two-fluid solution providesT _p-values which, though within the observational error, are larger than those obtained from the simultaneous three-fluid solution (at 1 AU, the difference amounts to about 30%). Thus, the -particles affect the temperature profile of the protons in the solar wind through heat exchange (mainly), dynamical friction, as well as through their contribution to the interplanetary electrostatic field.     

Hα line emission and infrared excess in Be stars

The H observations of a selected sample of bright Be stars are presented. The available infrared observations at K band (2.2 m) of these stars have been used to find the infrared excess emission. The analysis of the combined data show thatL _H, the luminosity of the H emission line, is proportional toL _IR, the luminosity of the infrared excess emission. The linear correlation betweenL _IR andL _H shows that both the infrared excess and the H line originate in a common region. It is also detected that the infrared excess emission is produced throughout the whole envelope whereas the H is emitted in some defined region of the circumstellar (CS) envelope.     

Spectrograph,filtergraph and magnetograph observations of the two-ribbon flare of 29 July, 1973

We present high resolution detailed observations of the class 3N two-ribbon flare of 1973, July 29 (McMath 12461), which was associated with the disappearance of a large filament (disparition brusque). This flare occurred in a diffuse bipolar magnetic region completely devoid of sunspots, and was further associated with a type IV radio burst and a soft X-ray event. Extensive H filtergraph, spectrograph and magnetograph records during the main phase of the flare suggest that downfalling and streaming material is present on both ribbons for several hours during the H emission enhancement, but only at a small number of points located both on and off the ribbons. We find a poor spatial correspondence between bright emission knots in the H ribbons and the positions of the observed downward motion. We conclude that the model of infall-impact of Hyder (1967a, b) is not consistent with our filtergraph and spectrograph observations.Presently at the University of Michigan, Ann Arbor, Michigan.