bluuebunny/crossref_metadata_2025 huggingface dataset:
Overabundance of Sodium in the Atmospheres of Massive Supergiants as a Possible Manifestation of Nena Cycle
Authors: Boyarchuk A.A. , Denisenkov P.A. , Hubený I. , Ivanov V.V. , Kubát I. , Lyubimkov L.S. , Sakhibullin N.A.
Published: July 2016

Studies of chemical composition of the atmospheres of F-K supergiants have revealed the existence of two specific peculiarities, deficit of carbon and excess of nitrogen. Anomalous abundances of C and N in yellow supergiants is explained by mixing of surface material with CNO-processed material of stellar interiors (the first dredge-up). Somewhat unexpectedly, F-K supergiants were found to show one more general chemical peculiarity: overabundance of sodium. Fig.1 shows the available values of [Na/H]=log[N(Na)/N(H)]*−log[N(Na)/N(H)]⊙ as summarized by Boyarchuk and Lyubimkov( 1983). Different symbols refer to data of various authors. Fig.1 shows that sodium overabundance increases with the decrease of surface gravity. For small log g it reaches [Na/H] ~ ~ 1. Recently Sasselov(1986) has suggested that this correlation is essentially a consequence of a relation between [Na/H] and a mass of supergiant.
Quantitative Spectroscopy of Wolf-Rayet Stars
Authors: Schmutz W.
Published: July 2016

Advances in theoretical modeling of rapidly expanding atmospheres in the past few years made it possible to determine the stellar parameters of the Wolf-Rayet stars. This progress is mainly due to the improvement of the models with respect to their spatial extension: The new generation of models treat spherically-symmetric expanding atmospheres, i.e. the models are one-dimensional. Older models describe the wind by only one representative point. The older models are in fact ‘core-halo’ approximations. They have been introduced by Castor and van Blerkom (1970), and were extensively employed in the past (cf. e.g. Willis and Wilson, 1978; Smith and Willis, 1982). First results from new one-dimensional model calculations are published by Hillier (1984), Schmutz (1984), Hamann (1985), Hillier (1986), and Schmutz et al. (1987a); more detailed results are presented by Schmutz and Hamann (1986), Hamann and Schmutz (1987), Hillier (1987a,b), Wessolowski et al. (1987), Hillier (1987c) and Hamann et al. (1987). These results demonstrate that the step from zero- to one-dimensional calculations is essential. The important point is that the complicated interrelation between NLTE-level populations and radiation field is treated adequately (Schmutz and Hamann, 1986; Hillier, 1987). For this interrelation it is crucial to model consistently not only the line-formation region, but also the layers where the continuum is emitted. In fact, it is the core-halo approximation that causes the one-point models to fail in certain aspects.
Spectral Analysis of the Wolf-Rayet Star HD 50896
Authors: Hamann W.-R. , Schmutz W. , Wessolowski U.
Published: July 2016

The helium spectrum of the WN5 star HD 50896 (EZ Canis Majoris, WR6) is studied. Our aim is to establish a technique which allows the determination of the parameters of a Wolf-Rayet star from a systematic analysis of its spectral lines. Since the method of “iteration with approximate Lambda operators” became available for application to expanding atmospheres (Hamann, 1986, 1987), we are now able to compare observed spectra to realistic model calculations (Hamann and Schmutz, 1987; Wessolowski et al., 1987).

We consider the non-LTE spectral formation in a spherically expanding atmosphere. The velocity field v(r) is specified in its supersonic part by the usual analytical law with the parameters v∞ (final velocity) and the exponent ß=1. The temperature structure is derived from the assumption of radiative equilibrium, but only approximately evaluated for the grey LTE case. The atmosphere is assumed to consist of pure helium. The model atom has a total of 28 energy levels, among these 17 levels of He I. The line radiation transfer is treated in the “comoving frame”.
Call H and K Emission in the Secondary Component of U Cephei
Authors: Okazaki Akira , Nakamura Yasuhisa , Katahira Jun-Ichi
Published: July 2016

U Cephei (V = 6.8–9.0, P = 2.493 d) is an eclipsing binary consisting of a B7V primary and a G8III-IV secondary component. This binary is one of the semidetached Algol systems showing soft X-ray emission which is probably associated with a hot corona surrounding the secondary component (White and Marshall 1983).

We made spectroscopic observations of U Cep with the coudé image-tube spectrograph of the 1.9-m telescope at Okayama Astrophysical Observatory on October 14, 1986. We obtained four spectrograms with a dispersion of 16 Å mm-1 covering λ λ3700—4300 Å during the primary eclipse. The first two exposures were made in a total eclipse, while the last two were slightly after the third contact. The CaII H and K emission lines appear clearly in all the spectrograms. Figure 1 represents an intensity tracing of one of these spectrograms.
Photometric and Polarimetric Observations of the RV Tauri Star AR Puppis
Authors: Raveendran A.V. , Rao N. Kameswara
Published: July 2016

RV Tauri stars are variable yellow supergiants and they display anomalous excesses in infrared radiation indicating the presence of cool and extended dust thermospheres, presumbly formed from the matter ejected by them (Gehrz 1972). AR Pup, recognised as a member of RV Tauri stars, shows strong CH and CN bands in the optical spectrum and is considered to be carbon-rich (Lloyd Evans 1974). During a programme of broad band polarimetric observations of carbon variables, AR Pup was found to exhibit a large and highly time-dependent linear polarisation (Raveendran & Kameswara Rao 1987).

During the period from 1987 January 20 to April 6, AR Pup was observed on 33 nights through standard B and V filters with the 34-cm reflector of the Vainu Bappu Observatory, Kavalur. We also obtained UBVRI polarimetry of AR Pup with the PRL - Polarimeter (Deshpande et al. 1985) attached to the 102-cm reflector on six nights during the same period. Present observations clearly indicate that the large time dependent variations in polarisation, both in the amount and wavelength dependence, observed at earlier epochs by us were not isolated events but were segments of a continuous variation which is cyclic and related to the light curve.
Observing the Nucleosynthesis from Core Collapse Supernovae
Authors: Fransson Claes
Published: July 2016

Since the appearance of the classical papers on stellar nucleosynthesis in the 1950’s most of the observational tests have been through indirect sources of information. Even though this has been rather successful (cf. various contributions in this volume), it represents only an average over all sources, yielding little information about specific stars. The most direct evidence comes from observations of young galactic supernova remnants (age less than ∼103 years). Unfortunately, the analysis of X-ray data are hampered by a lack of understanding of the detailed physics, eg. non-equilibrium and plasma effects, as well as by observational problems (Itoh and Nomoto, 1987). Optical observations (cf. Raymond, 1984) have given some valuable insight of eg. the oxygen-rich remnants. The analysis of these are, however, suffering from the fact that only a small fraction of the mass is seen in the optical.
The Composite Image of Sanduleak −69° 202, Candidate Precursor to SN 1987A in the LMC
Authors: Walborn Nolan R. , Lasker Barry M. , Laidler Victoria G. , Chu You-Hua
Published: July 2016

The image of Sk −69° 202 was scanned and analyzed on eight (of 32 available) blue through near-infrared photographic plates obtained at the prime focus of the Cerro Tololo Inter-American Observatory 4-meter telescope during 1974–1983. Both intensity syntheses of the image and density differences were derived by means of reference stars from the same plates, including the similar nearby object Sk −69° 203. Several of the density differences are shown in Figure 1. The analysis shows that the 12m blue supergiant in Sk −69° 202 (Star 1) has two companions with V magnitudes, position angles, and separations 315°, 3″ (Star 2) and 115°, 1.″5 (Star 3), respectively. Both companions appear to be early-type stars; there is no evidence for a bright red star in the system. The two companions are responsible for the spectra observed by the International Ultraviolet Explorer following the decline of the SN in the far UV, so that Star 1 has disappeared and was probably the progenitor. The most likely interpretation is that it was a post-red supergiant evolving blueward in the HR diagram.
A Rotating Stellar Collapse Model for Supernova 1987a
Authors: Nakamura Takashi , Fukugita Masataka
Published: July 2016

It is shown that the bunch structure of the Kamiokande neutrino events associated with SN1987a can be naturally understood, if one assumes that the core of the progenitor star was rotating moderately with q(≡ Jc/GM2) ≈ 3 with J the total angular momentum and M the gravitational mass of the core.

We assume that the presence of the observed gap, at least that between the second and the third bunch, is real and consider its implications in the dynamics of the core collapse. Let us define a nondimensional angular momentum q(≡ Jc/GM2) with J the total angular momentum and M the gravitational mass of the core. We assume that the value of q for the core of SN1987a was about 3. Then we expect that the effect of the angular momentum plays an important role when the size of the core r shrinks to < 107cm. In the spherically symmetric collapse model, the size of the unshocked homologous core is of the order of 107cm. Hence we expect that the core at the bounce is essentially governed by the spherically symmetric dynamics. To verify this point we may refer to the simulation by Symbalisty1. Our model almost corresponds to Model ROT2 in which one obtains a neutrinosphere with a roughly spherical radius of approximately 50km. We then expect that the infalling nonhomologous matter onto the core will liberate a gravitational energy of the order of 1052ergs.
The Light Curve of SN 1987 A
Authors: Schaeffer R. , Cassé M. , Mochkovitch R. , Cahen S.
Published: July 2016

We use a semi–analytical model of supernova light curves that extends Arnett’s scheme [1,2] to include the effect of recombination of hydrogen, helium and heavy elements in the expanding ejecta. Introducing in the model the physical parameters of Sanduleak −69 202, the salient characteristics of the light curve of SN 1987 A are reasonably reproduced over 100 days.
An X-Ray Investigation of Crab-Like Supernova Remnants
Authors: Wang Z. R. , Seward F. D.
Published: July 2016

The Crab Nebula is the most noticeable object in our Galaxy, and the remnant of the famous Chinese guest star appeared in 1054AD, the best association between supernova remnants(SNR) and ancient guest stars. Before seventies, the Crab Nebula was considered as a special SNR with different morphology and physical features from that of most SNRs, Now more and more Crab-like SNRs have been detected(Weiler 1985). It is necessary to make a systematical investigation for the Crab-like SNRs, especially for those with central pulsars because they offer us more physical messages than others.

The two associations SNR and PSR, the Crab Nebula with PSR 0531+21 and the Vela SNR with PSR 0833-45, were confirmed at the end of sixties and still were the only two associations before eighties. Recent years, PSR 1509-58 in MSH 15-52 and PSR 0540-69 in a SNR of LMC(Seward & Harnden 1984, Seward etal. 1984) as well as PSR 1951+32 in CTB 80 (Clifton et al. 1987, Fruchter etal. 1987) were discovered. On the other hand, the X-ray emission of PSR 1055-52 and others were detected (Cheng & Helfand 1983, Helfand 1983). Recently, we searched for the X-ray emission of isolated pulsars over more than thirty fields in Einstein observation. By use of the same instrument calibrstions, the X-ray luminosities of ten isolated pulsars and their surrounding nebulae are obtained. Let Lx be the total X-ray luminosity of a pulsar and its nebula in the 0.2-4.0 kev band, and E be the rotating energy loss rate of the pulsar, the following statistical relation is obtained by linear regression and shown as the line in Fig. 1.
On possible mass loss from the supergiant RHO Cassiopeia
Authors: Boyarchuk M.
Published: July 2016

The supergiant Rho Cas F8Ia has a very high luminosity. Astronomers have payed attention to this star in August 1946, when its by its brightness had dropped from 4.2 to 6.2. The systematic spectrographic observations of Rho Cas are beeing carried out at the Crimean Astrophysical Observatory since 1965. No large light variations were observed during that time.
Response of low-mass main sequence stars to accretion
Authors: Fujimoto Masayuki Y. , Iben Icko , Becker Stephen A.
Published: July 2016

When the massive component in a close binary system evolves to fill its Roche lobe, mass transfer occurs and gas is accreted onto the companion star. Recently, the response of the unevolved secondary to accretion has been studied by a number of authors, but the emphasis has been on relatively massive stars which have a radiative envelope (Ulrich and Burger 1976; Flannery and Ulrich 1977; Kippenhalm and Meyer-Hofmeister 1977; Neo et al. 1977). The results show that the mass accepting star becomes overluminous and grows in radius until rapid mass transfer ultimately brings the two stars into contact. Such changes in the structure are caused by the steep increase in the specific entropy in the outermost layers and only a small amount of mass (about a tenth of the initial mass of the star) is accreted before contact is made. Thereafter, the expansion of the common envelope will lead to mass loss from the system. It is also found that, for a given accretion rate, the radial increase is much more conspicuous for a smaller mass star.
Infrared observations and mass loss of the binary system V861 Sco
Authors: Tanzi E.G. , Maraschi L. , Tarenghi M. , Treves A.
Published: July 2016

V 861 Sco (HD 152667) is a well known single line binary(1,2).The proposed association with a variable X-ray source(3,4) has triggered renewed interest in the system. Recent optical, infrared and ultraviolet observations(5 - 12) have provided a better knowledge of its characteristics. A first estimate of the mass loss was given by Hutchings(13).

Here we report on a series of photometric observations in the infrared (from 1.25 to 4.8 µ) taken at various orbital phases which improve and extend previous measurements by Tanzi et al.(12)

The results give evidence of a phase modulated infrared excess which can be interpreted in terms of a non isotropic mass flow in the system or, alternately, of a contribution from a colder secondary component.
Stellar mass loss and galactic chemical evolution
Authors: Serrano A. , Peimbert M.
Published: July 2016

We summarize here some of the results that we have obtained from chemical evolution models. In particular, we discuss those aspects related to stellar mass loss, helium production, a varying heavy element yield and the very light stars.

The observed value of the helium to heavy element abundance ratio ΔY/ΔZ is about 3 (e.g. Lequeux et al. 1979). First theoretical estimates gave ΔY/ΔZ= 0.4 (Hacyan et al. 1976).
On the Accuracy of Frequency Determination by an Autoregressive Spectral Estimator
Authors: Kovács G.
Published: July 2016

The accuracy of frequency determination by a least squares technique for an autoregressive spectral estimator is studied and compared with the Fourier method. Using numerical tests the probability distribution function of the peak location is calculated. The autoregressive filter order is optimized in the sense of minimum variance of the peak location. Simple sinusoidal signals with additive Gaussian noise are considered and the effect of other components is only indicated. Generally, a filter order between 1/3 and 1/2 of the total data number and a not very dense data sampling, gives the most stable spectrum. The results are numerical.
Radiative Transfer and Solar Oscillations
Authors: Christensen-Dalsgaard Jørgen , Goode Philip R.
Published: July 2016

We consider the atmospheric behaviour of solar oscillations in a model including a detailed, semi-empirical atmosphere. Equations of radial and non-radial oscillation, with consistent treatment of the radiation field, are derived. These equations are solved in the radial, grey case; the results show that departure from the Eddington approximation has little effect on the properties of the oscillations. Preliminary results are presented for the non-radial case, indicating substantial deviations from the Eddington approximation when the optical thickness across a horizontal wavelength is of the order of or less than unity.
A New Method for determining the Helium Abundance in the Solar Atmosphere
Authors: Isaak G. R.
Published: July 2016

Recent observations of a cut-off frequency in the acoustic modes of the Sun (Claverie et al., 1981b) should help determine the mean molecular weight and, thereby, the helium abundance in the visible layers of the solar atmosphere. A first preliminary result of Y = 0.42 ± 0.04 is obtained for an assumed minimum photospheric temperature of 4400 K ± 200 K.
Solar Models with Low Opacity
Authors: Kuzurman P.A. , Pamyatnykh A.A.
Published: July 2016

Evolutionary models of the present Sun with standard and artifically low opacity of stellar matter are obtained and adiabatic nonradial oscillations of the models are computed. The opacity x in nonstandard model (which is the first in a series of future models with low χ) was taken half as much as the Cox-Stewart opacity. The central temperature in such model is approximately 10% below the ‘standard’ values, which can explain the neutrino experiment results. Unlike solar models with very low heavy element abundance, the low χ model has approximately standard mass concentration and distribution of the matter in the outer layers – specifically, the standard characteristics of the convection zone. Hence, the spectrum of adiabatic oscillations is similar to that of the standard models and has the same capabilities for the explanation of the observed pulsations.
Theoretical Eigenfrequencies of Solar Oscillations of Low Harmonic Degree l in Five-Minute Range
Authors: Shibahashi H. , Osaki Y.
Published: July 2016

We have calculated eigenfrequencies of radial and nonradial p-mode oscillations with low harmonic index l (l = 0, 1, 2, 3, and 4) for a standard solar model with normal composition and appoximately the correct age. It is found that theoretical eigenfrequencies calculated for our standard model agree approximately with observed peaks in the power spectra for the full-disk five minute oscillation of the Sun (Claverie et al., 1980; Grec et al., 1983; Scherrer et al., 1983) in agreement with other recent works (Christensen-Dalsgaard and Gough, 1980; Scuflaire et al., 1981). However, there still remains a slight discrepancy between theory and observations in such a sense that the theoretical eigenfrequencies are slightly lower than observations (see Figure 1).
The Study of Velocity Oscillations in the Solar Photosphere Using the Velocity Substraction Technique
Authors: Kobanov N.I.
Published: July 2016

A method of measurement of local line-of-sight velocities in the solar atmosphere by means of polarization optics is described. No spurious signals due to instrumental displacements of the spectrum arise with this method. The sensitivity of the method obtained is 0.3 m s-1, with a time constant τ = 5 s and input aperture 1.4ʺ x 4.5ʺ. Some preliminary results of the assessment of spatial characteristics of 5-min oscillations are included. Data are given to illustrate a center-to-limb variation of the spectrum of 5-min oscillations.
A New System for Observing Solar Oscillations at the Mount Wilson Observatory. I: System Design and Installation
Authors: Rhodes Edward J. , Howard Robert F. , Ulrich Roger K. , Smith Edward J.
Published: July 2016

In this paper we describe a new observing system which is currently nearing completation at the Mount Wilson Observatory. This system has been designed to obtain daily measurements of solar photospheric and subphotospheric rotational velocities from the frequency splitting of non-radial solar p-mode oscillations of moderate to high degree (i.e. l > 150). The completed system will combine a 244 x 248 pixel CID camera with a high-speed floating point array processor, a 32-bit minicomputer, and a large-capacity disc storage system. We are integrating these components into the spectrograph of the 60-foot solar tower telescope at Mount Wilson in order to provide a facility which will be dedicated to the acquisition of oscillation data.
Resonant Coupling between Solar Gravity Modes
Authors: Dziembowski W.
Published: July 2016

It is shown that in consequence of the parametric resonance, g modes of low spherical harmonic degree l are strongly coupled to the modes of high degree. The coupling limits the growth of lowl modes to very small amplitudes. For g1, l = 1 mode, the final amplitude of the radial velocity is of the order of 10 cm s-1. A mixing of solar core as a result of a finite-amplitude development of linear instability of this mode is thus highly unlikely.
On the Excitation of Oscillations of the Sun (Numerical Models)
Authors: Kosovichev A.G. , Severny A.B.
Published: July 2016

Numerical solutions of the general time-dependent gas-dynamical equations in linear adiabatic approximation are given for initial conditions imitating: (a) a central perturbation, (b) a boundary perturbation (in the convective envelope), and (c) a ‘shrinking’ of the Sun as a whole. For a variety of models of the Sun it is found that at the surface the radial component vr of velocity is much greater than the tangential component vt, and that the period T of stationary oscillations does not exceed 131m. The appearance at the surface of a g mode with period 160m is found to be improbable.

With the initial conditions adopted, a propagating wave is produced which is reflected successively from the centre to the periphery and back, producing 5-min oscillations at the surface of the Sun. Expansion of this wave into separate modes leads to a power spectrum qualitatively similar to that observed.
Excitation of the Solar Oscillations by Objects Consisting of y-Matter
Authors: Blinnikov S. I. , Khlopov M. Yu.
Published: July 2016

Modern development of particle physics makes it probable that new, still undiscovered, particles exist interacting with the ordinary matter by means of gravitation only. Okun suggested to call such particles the y-particles and to call the matter consisting of them the y-matter. We show that planet-like object orbiting inside the Sun and consisting of y-matter may explain 160 min nonradial solar oscillations.
Maunder Convection Mode on the Sun and Long Solar Activity Minima
Authors: Dogiel V. A.
Published: July 2016

A model of velocity field oscillations in the solar convective zone is suggested. The system of convective equations is investigated for a thin rotating spherical envelope when the rotation velocity is depended on the coordinates. It is shown that two different structures of convective cells (longitudinal, or latitudinal) can exist in the envelope depending on gradients values of the rotation velocity and Prandtl number.

It is supposed that two different regimes of convection (stationary and autofluctuating) are possible in the envelope when the angular velocity gradients are determined by the convection itself. In the case of autofluctuating regime the alternation of longitudinal and latitudinal structure of convection is realized.

If one assumes that on the Sun there exists an autooscillating convection regime, then the periods of the existence of latitudinal convection structure may be associated with long periods of activity minima since according to Cowling’s theorem, the action of the axisymmetric magnetic field generation mechanism isimpossible under conditions of axisymmetric velocity structures.
An Essay on Stellar Oscillations and Evolution
Authors: Iben Icko
Published: July 2016

It is cautioned that solar models adjusted in such a way as to achieve a match between theoretical solar oscillation characteristics and observed ones may produce neutrino fluxes inconsistent with the observations and that this is likely to be explicable as a deficiency in modeling that portion of the envelope which is most strongly affected by uncertainties in the treatment of convection. Then follows a summary of how the results of pulsation theory and of stellar evolution theory have been used together to learn about the structure and evolution of RRLyrae stars, classical Cepheids, and high luminosity AGB stars.
The Atmosphere of a Probably Very Young by Dra-Type Flare Star
Authors: de la Reza R. , Butler C.J. , Torres C.A.O. , Batalha C.C.
Published: July 2016

The flare star Gliese 182 (dM0.5e) seems to be only known single BY Dra type that presents Li in its atmosphere. This characteristic and others, principally activity, and high rotation, indicate that probably this is a very young object. We analyse in this work the possibility to interpret with a single typical model for a dMe atmosphere, some observed lines of Gliese 182 and to predict others. The lines belong to the following atoms; Li I, H I, He I, He II, C I, C II. A relatively good agreement exists only for neutral lines but not for ionized lines. The upper chromosphere and transition region must be studied in more detail. Some comparison are made with the UV observations of the double star BY Dra. Empirical relatively high X-ray fluxes are predicted for both stars. The Li abundance of Gliese 182 is confirmed to be similar to that of the interstellar medium.
Einstein and IUE Observations of Nearby Red Dwarfs
Authors: Johnson Hugh M.
Published: July 2016

This paper summarizes data for 40 representative nearby stars from one guest observer's coordinated programs with the Einstein observatory or IUE observatory. The coronal X-ray, chromospheric ultraviolet, and auxiliary optical properties of sets of these stars are tabulated or illustrated in several ways. Factors of stellar duplicity are shown to be quite prevalent in presenting the observations. The most luminous X-ray dwarfs below the Sun are strongly prone to binary status. X-ray luminosity, and the ratio of chromospheric flux to X-ray flux, are dependent on photospheric radius. A very long period BY Draconis variable of type dM6e (HH And) is a detected X-ray source, and some presumably quite old (halo) stars are detected.
X-Ray Observations Of Stellar Flares
Authors: Haisch Bernhard M.
Published: July 2016

The history of stellar X-ray flare observations prior to EINSTEIN is reviewed. X-ray light curves as measured by the IPC are then presented for all time resolved flare events discovered as of July 1982 in the EINSTEIN data set. These light curves are analyzed in terms of solar-like loop models to derive densities, temperatures, loop lengths, magnetic field strength lower limits, etc. The failure of the model to adequately represent the observations in the case of the YZ CMi flares is discussed. The relationship of X-ray to optical emission and X-ray to UV emission is considered from both an observational and a theoretical viewpoint. It is concluded that the characterization of a flare by a single, time averaged ratio, Lx /Lopt , is not physically significant.
Light Curves and Ca II Emissions of VT11 Tauri During 1981-82
Authors: Nha Il-Seong , Young Oh Jun
Published: July 2016

The light variation of V711 Tauri was first discovered by Cousins, who suspected the variation with an amplitude of ΔV = 0.mll. This light variation was confirmed by Landis and Hall (1976). This star has been identified as the brightest RS CVn-type star by Bopp and Fekel (1976). Bopp et al. (1977), using Cousins' old data and their data made nearly 13 years later than those of Cousins, found that the observations show the same light curve shape and amplitude and the minimum light falls very nearly at 0.P0 computed with their ephemeris.
Numerical Analysis of Orbital Period Variations and a Mechanism for Changes in the Light Curve of VW Cep
Authors: Xuefu L. , Chengzhong L.
Published: July 2016

The WUMa contact binary VW Cep has a period of 0.2783 days, spectral type G5+K1 and mass 1.1+0.4. Mʘ. Our three-colour photoelectric measurements made in Sept. and Oct. 1964 confirmed the existence of the Kwee effect in this system. We believe that if the Kwee effect is to be explained in terms of moving gas streams the influence of magnetic fields must be considered. It is assumed that there is a deep convection zone on the primary accompanied by a dipole magnetic field. This field is distorted by the moving gas streams to form a ring-like configuration with an enhanced field strength close to the inner Lagrangian point, L1 (see figure l), where large groups of spots form. We suppose the magnetic field in the spots to be 5000G and the general field to be ~10–20 G.
Observational Approach and Perspective
Authors: Vaiana G.S.
Published: July 2016

Goldberg: Well you did not cover more than half of my planned talk! (laughter). Let me comment on interferometric techniques, in particular speckle imaging which you mentioned. Doing speckle imaging with the largest telescopes now available will not give you better than the theoretical resolving power of the telescope. With a 4m telescope that is about 30 marc sec in the visible. That happens to be the radius of the supergiant Betelguese. So you are not going to achieve much with speckle imaging on these stars. One technique which has not been adequately exploited is that of lunar occultation which can give much better angular resolution than speckle, of the order of 2-3 marc sec. By using suitably chosen filters it may be possible to see structure on the disks of stars.
Perturbations due to the Asteroid Belt
Authors: Fu Tong , Zhen Chen
Published: July 2016

A new expansion for the gravitational potential of the asteroid belt is derived in this paper on the basis of binomial expansions. Its advantages are: (1)the unified form both for the inner and for the outer regions of the belt; (2)suitability for discussing the motions of the celestial bodies with perihelions within but apohelions beyond the belt; (3)rapidity of convergence.

The perturbations due to the asteroid belt are studied by using our expansion.
Families of Asteroids
Authors: Kozai Yoshihide
Published: July 2016

The numbered asteroids are classified into families by a new method proposed by the author(Kozai, 1979a) and their characteristics are studied by several aspects. It seems to the author that there are two kinds of the families, one being very compact in the phase space and containing many faint as well as a few bright asteroids and one being rather loose and bounded by secular and mean motion commensurable regions.
Resonant Asteroidal Motion in the Kirkwood Gaps: A Three-Dimensional Study
Authors: Scholl H. , Froeschle C.
Published: July 2016

Resonant asteroidal motion is investigated over 17 000 years in a three-dimensional elliptical model Sun-Jupiter-Asteroid averaged by Schubart's method à la Poincarè. Orbits remain trapped in the resonance over this period. The various stability mechanisms are discussed. With respect to their behaviour of ω and ῶ, our resulting orbits reveal 5 distinct classes. These 5 classes can be described in Schubart's topology for the planar problem. As compared to the planar case, eccentricities of orbits in the three-dimensional model vary more strongly. This is an important result for the problem of the delivery of meteorites.
Construction of Periodic Orbits, Problems of Stability and Period Determination, in the Elliptical Non-Planar Restricted Problem
Authors: Edelman Colette
Published: July 2016

Periodic orbits in a fixed frame are constructed in the vicinity of nonperiodic solutions of the non perturbed problem. In a first phase, approximate initial conditions are found and in a second phase more accurate initial conditions obtained are used in order to check the periodic orbit by numerical integration of the three-body problem. Some peculiar solutions are found, for example, orbit with nearly zero angular momentum. A study of stability of periodic solutions is proposed with an approximation of the monodromy matrix Φ (T,o),not requiring numerical integration of the 6x6 variational linear system. Finally, some numerical problems of period determination are outlined.
Asymptotic Approach to Mirror Conditions as a Trapping Mechanism in N-Body Hierarchical Dynamical Systems
Authors: Roy Archie E.
Published: July 2016

The consequences for hierarchical stability of almost circular almost coplanar, low perturbation orbits in an n-body hierarchical dynamical system is discussed. It is shown that frequent close approaches to mirror conditions with subsequent reversing of perturbations is ensured by such properties. The part played by near commensurabilities in mean motion is also discussed, the Sun-Jupiter-Saturn case being taken as an example.
Doubly Asymptotic Orbits at the Unstable Equilibrium in the Elliptic Restricted Problem
Authors: Perdios E.
Published: July 2016

Outgoing asymptotic orbits at a collinear Equilibrium point of the elliptic restricted three-body problem are constructed analytically and numerically and those which intersect perpendicularly the axis of symmetry are selected by means of a numerical procedure of differential corrections. Due to the symmetry properties of the problem, the latter orbits terminate asymptotically back to the equilibrium point and therefore provide a kind of “asymptotic trapping” at the unstable equilibrium, a trapping mechanism based on "long duration of passage" rather than stability of motion.
V 4049 SGR
Authors: McCarthy M.F. , Lasker B.M. , Kinman T.D.
Published: July 2016

V 4049 Sgr was detected by the authors as a possible symbiotic star on Curtis Schmidt objective prism plates. This star is Nova Sgr 1978 and was first discovered by Stenholm and Lindstrom. When observed in 1979 With SIT specgrograph on CTIO 4 m telescope the outstanding features were the presence of very strong lines of [FeVII] chiefly at 6085 A where its flux relative to H α is 1.6. Details have been published in Pub. astr. Soc. Pacific, 93, 470 (1981).
The Kuwano peculiar object (PU Vulpeculae)
Authors: Belyakina T.S. , Gershberg R.E. , Efimov Yu.S. , Krasnobabtsev V.I. , Pavlenko E.P. , Petrov P.P. , Chuvaev K.K. , Shenavrin V.I.
Published: July 2016

U, B, V, J, H, K photometry, polarimatry and spectroscopy of this peculiar object was made from August 1979 to December 1980. During 1979 it was at a phase of stable maximum brightness with variations of less than 0m.2 in magnitude and less than 0m.1 in colour. A change occurred at the beginning of 1980;the object was 0m.5 fainter in mid March and then faded rapidly. During the rapid fading the object became redder in U-B and B-V, and there was an intrinsic polarization of about 1%. At minimum in September 1980, B-V become even bluer than at maximum, while the 1.2-2μ flux was twice lower in October 1980 than in April 1979. At maximum the spectrum was of type F; the Ball lines indicating a luminosity higher than that of a normal supergiant.
Symbiotic star UV emission and theoretical models
Authors: Kafatos M.
Published: July 2016

Observations of symbiotic stars in the far UV have provided important information on the nature of these objects. The canonical spectrum of a symbiotic star, e.g. RW Hya, Z And, AG Peg, is dominated by strong allowed and semiforbidden lines of a variety of at least twice ionized elements. Weaker emission from neutral and singly ionized species is also present. The Mg II doublet is usually very strong and may be associated with the M giant primary. A continuum may or may not be present in the 1200 - 2000 A range but is generally present in the range 2000 - 3200 A range, the latter arising from free-free and bound-free emission in the same nebula that is responsible for the UV line emission (CI Cyg, RW Hya, RX Pup). The suspected hot subdwarf continuum is seen in some cases in the range 1200 - 2000 A (RW Hya, AG Peg, SY Mus).
The evolutionary status of symbiotic stars
Authors: Rudak Bronislaw
Published: July 2016

The evolutionary relations between symbiotic stars and cataclysmic variables are presented. The symbiotic stars are assumed to be long period detached binaries containing a carbon-oxygen degenerate primary and a red giant losing its mass through a spherically symmetric wind. Such systems can be obtained in Case C evolution, provided a common envelope during a rapid mass transfer phase was not formed. The same way recurrent novae containing a red giant as a secondary component may be produced. The factors influencing the differences between symbiotic stars and nova-type stars are discussed.
Pioneer 10 and Voyager Observations of the Interstellar Medium in Scattered Emission of the He 584 A and H Lyα 1216 A Lines
Authors: Shemansky D.E. , Judge D.L. , Jessen J.M.
Published: July 2016

The combination of Pioneer photometric and Voyager spectrometric observations of EUV interstellar-interplanetary emissions in the region beyond 5 AU have been applied to a determination of atomic hydrogen and helium densities. These density estimates obtained from direct measurement of scattered radiation depend on absolute calibration of the instruments, in the same way as other earlier determinations based on the same method. However, we have combined the spacecraft data with daily full sun averages of the H Lya 1216 A line obtained by the Solar Mesospheric Explorer (SME) satellite, to obtain a measure of atomic hydrogen density independent of instrument absolute calibration. The method depends on observations of long and short term temporal variability of the solar line over a 1 year period, and the fact that the ISM is optically thick. The density estimates from preliminary work on these observations are [H] = 0,12 cm-3 and [He] = .016 cm-3, giving a density ratio close to the cosmic abundance value, in contrast to some earlier results indicating a depletion of atomin hydrogen. We have obtained estimates of galactic background emissions in the signals of both spacecraft.
MgII Spectra of Late Type Stars Used to Probe the LISM
Authors: Beckman J.E. , Crivellari L. , Franco M.L. , Molaro P. , Vladilo G.
Published: July 2016

IUE spectra of Mg II h and k in late type dwarfs and giants have been used to detect and measure absorption components due to the LISM. This technique gives a method of probing the awkward range from d = 3 pc to d = 80 pc from the sun . In spite of interpretational uncertainties we can plot the HI component of the LISM well enough to confirm it as a cloud some 20-30 pc in extent, peaking sharply in density towards , moving towards the sun from , at 28 Km/sec. The “hole” towards is confirmed, suggesting a solar position close to the cloud's edge in this direction.
A High-Resolution Study of Local Interstellar Sodium
Authors: Ardeberg A. , Lindgren H. , Maurice E.
Published: July 2016

A high-resolution spectroscopic investigation has been made of interstellar lines of sodium. From identifications of D1 and D2 line components concentrations of interstellar sodium gas have been studied. Some preliminary data are provided on the spatial distribution of stronger sodium concentrations.
Optical Polarization as a Probe of the Local Interstellar Medium
Authors: Tinbergen J.
Published: July 2016

The use of interstellar polarization as a measurement tool for dust or magnetic field presents practical difficulties (dust and magnetic field configurations inextricably mixed up; limited number of suitable stars). This general rule applies even more in the local environment, for which the polarizations are small and the influence of errors of observation changes in character. Because of this, the use of polarimetry and the design of polarimetric observing programmes for the local interstellar medium must be approached with even greater care than in the general case. I propose in this review to amplify this point, so that the reader can judge for himself to what extent he can use published results and can also, given the opportunity and instrumentation, design an observing programme that will really pay off.
Observations of Highly-Ionized Interstellar Iron
Authors: Hobbs L.M.
Published: July 2016

The spectra of 24 stars, including 5 at distances d < 200 pc, have been observed in the regions of the coronal [Fe X] λ6375 and [Fe XIV] λ5303 lines at detection limits near an equivalent width of 1 mÅ in the best cases. In general agreement with predictions based on a multi-phase model of the interstellar medium, no absorption which can be attributed to Fe X or Fe XIV ions in hot interstellar gas emitting the soft x-ray background is seen in any of these spectra, except for two. Toward λ Cephei an absorption line near λ6375 is measured with an equivalent width of 8.1 ± 2 mÅ, a width corresponding to 20 ± 5 km s-1 or a temperature T ≤ (0.5 ± 0.25) x 106 °K, and, if it is caused by Fe X ions, a radial velocity of -355 km s-1. On that hypothesis, the hot interstellar gas constitutes at least 63% of the column density of gas along this light path.
A Neutral Gas Jet in a Low Velocity Shock Front at the Boundary of the Draco Nebula
Authors: Kalberla P.W.M. , Herbstmeier U. , Mebold U.
Published: July 2016

21-cm line observations with the Westerbork Synthesis Radio Telescope of a dust and molecular filament at the boundary of the Draco Nebula (l≈ 91°, b≈ 38°) reveal a jet-like neutral hydrogen feature funneling through an outlet in the low velocity shock front at the interface between the Draco Nebula and the surrounding gas. The jet-like feature is apparently connected with a high velocity filament at VLSR = -180 km s-1. We suggest that the soft x-ray emission observed in the area is thermal bremsstrahlung produced by the deceleration of high velocity gas in galactic gas.
Non Equilibrium Ionization in the Local Hot Bubble
Authors: Arnaud M. , Rothenflug R. , Rocchia R.
Published: July 2016

Soft X-ray surveys proved the existence of a local hot bubble surrounding the solar system (Mc Cammon et al 1983). Recently two experiments measured the spectrum of this hot interstellar medium with solid state detectors during rocket flights between 300 and 1000 eV (Rocchia et al 1984). The good resolution of the experiment permitted to measure CV, CVI and OVII line emissivities with good accuracy. We use these data to put some constraints on a model where the emission comes from a supernova remnant expanding in a finite pressure medium (Cox and Anderson 1982). We show the importance of non equilibrium ionization phenomena.
Introduction
Authors: Philip A.G. Davis
Published: July 2016

The last meeting on the determination of radial velocities was held at the University of Toronto, June 20 - 2A 1966, eighteen years ago. Five of the participants of this meeting were present at that meeting; Abt, Batten, Bertiau, Fehrenbach and Griffin. The lead article was “Photoelectric Measurements of Radial Velocities” by Griffin, followed by “Radial Velocities From Image Tube Spectra” by Rubin, Ford and Christy. These were the major new methods of determining radial velocities.

This meeting was planned to discuss the major advances made in the accuracy with which radial velocities can now be measured, and the applications of these methods to astronomical problems. I made a formal proposal at the Commission 30 meetings in Patras, Greece, to hold such a meeting in 1984 and the members of the commission ratified the idea. Subsequently, proposals were made to the Executive Committee of the IAU for sponsorship and to the National Science Foundation for financial support. Union College provided the first financial support and agreed to act as host for the meeting. The result of these activities is the presence of all of you in Schenectady for this meeting. I trust that it will be a productive meeting and I wish you all success with your deliberations.
Digital Stellar Speedometry
Authors: Latham David W.
Published: July 2016

Many areas of research have been opened up by the advent of instruments that can mass-produce radial velocities for large numbers of faint stars with precisions better than ± 1 km s−1. This paper summarizes the instruments and techniques in use at Center for Astrophysics (CfA), and the performance that they achieve for the digital speedometry of stars.
Cross-Correlation Spectrocsopy Using Coravel
Authors: Mayor M.
Published: July 2016

Several studies are reviewed to illustrate the possibilities of cross-correlation spectroscopy to derive rotational velocities, macroturbulence, metallicities, magnetic fields and information on oscillation modes.

The validity of radial-velocities of SB2 systems derived from the cross-correlation device has sometimes been criticized. The total absence of any basis to this criticism can easily be demonstrated. Indeed, this method is well suited to the study of SB2 with low radial velocity amplitudes, as for example, visual binaries.

Finally, as a result of different radial-velocity surveys carried out with CORAVEL, the eccentricity-period relations are discussed, showing the concurrent influence of the tidal circularization, circularization by mass-exchange and the dependence of the initial eccentricity distribution with the orbital period.
Radial Velocities of Late-Type Population II Stars
Authors: Ardeberg A. , Lindgren H.
Published: July 2016

Early radial-velocity work on high-velocity stars has been summarized. Present samples of such stars have been reviewed. Selection methods and sample bias have been discussed. Spectroscopic as well as photometric methods have been examined. In order to find a reasonably bias-free sample of late-type stars of Population II, photometric survey techniques have to be applied. Our survey for cool Population II stars is presented. With uvby photometry we have covered a total of about 5000 stars in an attempt to derive an unbiased sample of late-type stars suitable for a study of galactic distribution and kinematical properties as a function of evolutionary phase. Especially for the metal-poor stars of our sample we have made highaccuracy CORAVEL scanner measurements of radial velocities. So far, around 1700 stars have been observed for radial velocities, most of them more than once. The CORAVEL measurements have been very successful also for stars with extremely low abundance of heavy’ elements. Many previously unknown high-velocity stars have been found. Some of them have very high radial velocities. A comparison between our radial-velocity data and our preliminary metallicity indices confirms the early evolutionary phase reached in our survey. Our results also seem to confirm the limited ranges occupied by Intermediate Population II in metallicity and in radial velocity.
Les Mesures de Vitesses Radiales au Prisme Objectif Dans Le Programme Hipparcos
Authors: Fehrenbach Ch.
Published: July 2016

L’Organisation Européenne de Recherches Spatiales (E.5.A.) doit lancer en 1986 un satellite, Hipparcos, pour exécuter un programme astrométrique.

La description complète du projet et des programmes est donnée dans le Compte Rendu du Colloque de Strasbourg (22-23 février 1982), publication E.S.A. SP-177. Le programme général comprend la mesure de la position de 200 000 étoiles dont environ 100 000 sont prioritaires. 1000 d’entre elles sont plus proches que 50 parsecs.

La durée du vol doit permettre d’obtenir des mouvements propres. La précision attendue est de 0,002" par an. Un satellite ultérieur permettra d’améliorer cette précision. Il est important de compléter ces mouvements propres par des déterminations de Vitesses Radiales (VR).

Il est utile d’étudier rapidement la précision de ces VR et la possibilité de les mesurer.