bluuebunny/crossref_metadata_2025 huggingface dataset:
Results from Kodaikanal Synoptic Observations
Authors: Sivaraman K. R.
Published: July 2016

The synoptic observations of Kodaikanal form one of the longest unbroken solar data from the beginning of the 20th century to the present day, and consists of the white light and monochromatic images of the sun. In this review, I shall discuss the results of the investigations in two areas using these data: (i) Tilt angles of the magnetic axes of bipolar spot groups, and (ii) structure and dynamics of large scale unipolar magnetic regions on the solar surface.

The observed properties and patterns of behaviour of the tilt angles can be used as effective diagnostics to infer the physical conditions in the subsurface layers of the sun, and thus get an insight into the physical effects that act on the rising magnetic flux tubes during their journey through the convection zone to the surface.

The second topic of discussion here, namely, the studies of the dynamics of unipolar regions over several solar cycles, show that the global solar activity has a high latitude component which manifests in the form of polar faculae, in addition to the well known sunspot activity at the middle and low latitudes. This raises the question about the origin of this high latitude component.
22-Year Periodicity in the Solar Differential Rotation
Authors: Javaraiah J.
Published: July 2016

Using the data on sunspot groups compiled during 1879–1975, we determined variations in the differential rotation coefficientsAandBduring the solar cycle. The variation in the equatorial rotation rateAis found to be significant only in the odd numbered cycles, with an amplitude ∼ 0.01μrads−1. There exists a good anticorrelation between the variations of the differential rotation rateBderived from the odd and even numbered cycles, suggesting existence of a ‘22-year’ periodicity inB. The amplitude of the variation ofBis ∼ 0.05μrads−1.
Coronal Structures as Tracers of Sub-Surface Processes
Authors: Pevtsov Alexei A. , Canfield Richard C.
Published: July 2016

The solar corona – one of the most spectacular celestial shows and yet one of the most challenging puzzles – exhibits a spectrum of structures related to both the quiet Sun and active regions. In spite of dramatic differences in appearance and physical processes, all these structures share a common origin: they are all related to the solar magnetic field. The origin of the field is beneath the turbulent convection zone, where the magnetic field is not a master but a slave, and one can wonder how much the coronal magnetic field “remembers” its dynamo origin. Surprisingly, it does. We will describe several observational phenomena that indicate a close relationship between coronal and sub-photospheric processes.
Analysis of the 9th November 1990 flare
Authors: Joshi Anita , Uddin Wahab
Published: July 2016

In this paper we present complete two-dimensional measurements of the observed brightness of the 9th November 1990Hαflare, using a PDS microdensitometer scanner and image processing software MIDAS. The resulting isophotal contour maps, were used to describe morphological-cum-temporal behaviour of the flare and also the kernels of the flare. Correlation of theHαflare with SXR and MW radiations were also studied.
Tessellation of SoHO Magnetograms
Authors: Srikant R. , Singh Jagdev
Published: July 2016

A gradient based algorithm which divides arbitrary images into non-overlapping surface filling tiles of opposite polarity is used to study the flux and size distributions of large scale magnetic flux concentrations in solar and heliospheric observatory (SoHO) magnetograms. The mean absolute flux and size of the concentrations at the considered scale is found to be about 1.7 × 1018Mx and 5.2 Mm for both polarities. The form of the flux distribution is characterized by a skewness ofα3= 4.9 and a kurtosis ofα4= 42.8. The fall in the distribution in the range 6.5 × 1017Mx to 5 × 1018Mx is described by an exponential fit, in agreement with a model for the sustenance of quiet region flux.
Magnetoconvection and the Solar Dynamo
Authors: Nordlund Å. , Dorch S. B. F. , Stein R. F.
Published: July 2016

We review current understanding of the interaction of magnetic fields with convective motions in stellar convection zones. Among the most exciting recent results is the discovery that magnetic fields need not primarily be confined to the stable layer below the convection zone; numerical simulations have shown that surprisingly, strong magnetic fields can be maintained in the interior of the convection zone.
Large-scale Flow and Transport of Magnetic Flux in the Solar Convection Zone
Authors: Ambrož P.
Published: July 2016

Horizontal large-scale velocity field describes horizontal displacement of the photospheric magnetic flux in zonal and meridian directions. The flow systems of solar plasma, constructed according to the velocity field, create the large-scale cellular-like patterns with up-flow in the center and the down-flow on the boundaries. Distribution of the largescale horizontal eddies (with characteristic scale length from 350 to 490 Mm) was found in the broad equatorial zone, limited by 60° latitude circles on both hemispheres. The zonal averages of the zonal and meridian velocities, and the total horizontal velocity for each Carrington rotation during the activity cycles no. 21 and 22 varies during the 11-yr activity cycle. Plot of RMS values of total horizontal velocity is shifted about 1.6 years before the similarly shaped variation of the magnetic flux.
Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo
Authors: Belvedere Gaetano , Pipin V. V. , Rüdiger G.
Published: July 2016

Extended Abstract

Recent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).
Cyclical Variation of the Quiet Corona and Coronal Holes
Authors: Sakurai Takashi
Published: July 2016

Recent advances in the understanding of the quiet corona and coronal holes are reviewed. The review is based on long-term accumulation of data from eclipse observations, coronagraph observations, helium 10830 Å spectroheliograms, and X-ray observations.
Exploring Coronal Structures with SOHO
Authors: Karovska M. , Wood B. , Chen J. , Cook J. , Howard R.
Published: July 2016

We applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.
Solar Wind Variation with the Cycle
Authors: Veselovsky I. S. , Dmitriev A. V. , Suvorova A. V. , Tarsina M. V.
Published: July 2016

The cyclic evolution of the heliospheric plasma parameters is related to the time-dependent boundary conditions in the solar corona. “Minimal” coronal configurations correspond to the regular appearance of the tenuous, but hot and fast plasma streams from the large polar coronal holes. The denser, but cooler and slower solar wind is adjacent to coronal streamers. Irregular dynamic manifestations are present in the corona and the solar wind everywhere and always. They follow the solar activity cycle rather well. Because of this, the direct and indirect solar wind measurements demonstrate clear variations in space and time according to the minimal, intermediate and maximal conditions of the cycles. The average solar wind density, velocity and temperature measured at the Earth’s orbit show specific decadal variations and trends, which are of the order of the first tens per cent during the last three solar cycles. Statistical, spectral and correlation characteristics of the solar wind are reviewed with the emphasis on the cycles.
Remote Sensing of the Heliospheric Solar Wind using Radio Astronomy Methods and Numerical Simulations
Authors: Ananthakrishnan S.
Published: July 2016

The ground-based radio astronomy method of interplanetary scintillations (IPS) and spacecraft observations have shown, in the past 25 years, that while coronal holes give rise to stable, recurring high speed solar wind streams during the minimum of the solar activity cycle, the slow speed wind seen more during the solar maximum activity is better associated with the closed field regions, which also give rise to solar flares and coronal mass ejections (CME’s). The latter events increase significantly, as the cycle maximum takes place. We have recently shown that in the case of energetic flares one may be able to track the associated disturbances almost on a one to one basis from a distance of 0.2 to 1 AU using IPS methods. Time dependent 3D MHD models which are constrained by IPS observations are being developed. These models are able to simulate general features of the solar-generated disturbances. Advances in this direction may lead to prediction of heliospheric propagation of these disturbances throughout the solar system.
Prominence Spectra and Their Interpretation
Authors: Hirayama Tadashi
Published: July 2016

In this report I will concentrate on the spectroscopic observations and interpretations of quiescent prominences and briefly discuss the main difference between quiescent prominences and active prominences. Since the last prominence colloquium was held in 1971 (Bruzek and Kuperus, 1972), remarkable progress has been made in this particular field by the cooperative and competitive efforts of the groups in Boulder, Hawaii, Kiev, Kitt Peak, Kyoto and Oslo. The contribution from the Skylab data is also a really great one. Earlier works are summarized in Tandberg-Hanssen’s book (1974).
The Optical Thickness of Quiescent Prominences in the Ca II K Line and the Central Reversal in the Spectral Lines
Authors: Kubota Jun
Published: July 2016

During the period from September 1977 to March 1978, spectroscopic observations of quiescent prominences were made at the Kwasan Observatory with the horizontal solar telescope and the grating spectrograph. The spectra of lower Balmer, Ca II infrared triplet and H and K, Na I D and He I D3 lines were photographed simultaneously with a mean dispersion of 0.5 Å/mm.
Some Recent Results in Quiescent Prominence Spectrometry
Authors: Landman Donald A.
Published: July 2016

This paper describes some recent results of our quiescent prominence spectrometry program at the Mees Solar Observatory on Haleakala. The observations were made with the 25 cm coronagraph/coudé spectrograph system using a silicon vidicon detector. This detector consists of 500 contiguous channels covering approximately 6 or 80 Å, depending on the grating used. The instrument is interfaced to the Observatory’s PDP 11/45 computer system, and has the important advantages of wide spectral response, linearity and signal-averaging with real-time display. Its principal drawback is the relatively small target size. For the present work, the aperture was about 3″ × 5″. Absolute intensity calibrations were made by measuring quiet regions near sun center.
Helium Abundance from Optical Spectra of Quiescent Prominences
Authors: Hirayama T. , Nakagomi Y. , Okamoto T.
Published: July 2016

In 1971 one of the authors of the present investigation tried to determine the abundance ratio of helium to hydrogen and found it to be 5 ~ 8% by number (Hirayma, 1971). Quite recently Heasley and Milkey (1978) reported it to be 10 ± 2.5%. This paper describes another attempt to determine the abundance of helium, from the observations using the 25 cm coronagraph at Mt. Norikura for 11 quiescent prominences during 1971-1977. We concentrated our effort on the observation of the faintest part of the prominence because it is much easier to interpret. Figure 1 shows the intensity ratio of Hel 3888 to the hydrogen Balmer H8line plotted against the total intensity of the H7line. We can see that the fainter part of the prominence, i.e. the left part, has generally stronger emission in helium. We infer from this figure that the upper limit to the intensity ratio of helium to hydrogen is attained at a value of 0.7 ± 0.05.
Polarimetric Observations and Magnetic Field Determination in Prominences
Authors: Leroy J.L.
Published: July 2016

The magnetic field may be the most important physical parameter in the explanation of the “prominence” phenomenon and it plays a major role in all the theoretical models. Therefore, it is not amazing that a lot of work has been devoted to measuring the magnetic vector. Good reviews of the present state of our knowledge on this topic have already been given by Rust (1972), Smolkov and Bashkirtsev (1973) and Tandberg-Hanssen (1974). In the following, I shall describe only the problems and results which follow from measurements of the magnetic field in the prominence material itself. Data deduced from measurements of the magnetic field in adjacent layers of the solar atmosphere (chromosphere, corona) will be found in other sections of this Colloquium.
The Hanle Effect and the Determination of Magnetic Fields
Authors: Bommier V. , Sahal-Bréchot S.
Published: July 2016

A new research area has recently been developed in solar physics, i.e. the determination of magnetic fields by means of the interpretation of the two measured parameters describing the linear polarization of spectral lines (Leroy et al., 1977, Sahal-Bréchot et al., 1977, Leroy 1977a, b, 1978, Stenflo 1977, 1978, Sahal-Bréchot and Bommier 1977, Bommier and Sahal-Bréchot 1978). In solar prominences, this linear polarization is due to resonance scattering of the incident radiation field; the effect of the magnetic field B (Hanle effect) leads to a rotation of the polarization vector and a decrease of the degree of linear polarization. Both these parameters do depend on the strength and the direction of B and the dependence may be calculated using the theory of quantum optics and optical pumping.
A Magnetic Field Reconnection Model of Quiescent Solar Prominences
Authors: Raadu M.A.
Published: July 2016

Quiescent prominences are associated with neutral lines in the vertical component of the photospheric magnetic field. Three distinct classes may be distinguished (Leroy, 1978) namely: polar crown prominences, those above a bipolar region neutral line and those between two different bipolar regions. It is reasonable to expect differences in the process of formation and resulting structure between these three classes.
Active Prominences
Authors: Malville J. McKim
Published: July 2016

Those prominences which are identified as active lie near the middle of a large group of objects found in the low corona bordered on the high energy side by flares and on the low energy side by quiescent prominences. Known by descriptive terms such as eruptive, surge, spray, tornado, and loop, active prominences typically have shorter lifetimes, broader line widths, larger internal motions, and stronger internal magnetic fields than quiescent prominences (Tandberg-Hanssen, 1974). When dealing with specific examples, however, it is often difficult to establish a necessary and sufficient condition for classification of such an object as an active prominence. The ambiguity at the low energy end involves “hybrid” objects which possess features of both quiescent and active prominences. For example, the active region filament may have a lifetime of several days, have large internal motions and relatively strong magnetic fields. The stable hedgerow quiescent prominence may contain small regions with large widths and large velocities. On the average, a quiescent will typically erupt every five to eight days, (Serio, et al., 1978; Bryson and Malville, 1978) and at those times a prominence is transformed from the quiescent to the active state. For these objects something other than morphology, velocity fields, or even magnetic fields is necessary to specify their condition; something less symptomatic and more fundamental is required. That necessary parameter may be, I shall suggest, the total current, J, flowing in the structure.
Heating of Coronal Loops by Fast-Mode MHD-Waves
Authors: Habbal S.R. , Holzer T.E. , Leer E.
Published: July 2016

Loops in the corona, ranging in size from a few hundredths of a solar radius to a few tenths are observed in X-rays and EUV (Vaiana et al., 1976; Levine and Withbroe, 1977). Their temperatures are in the 2 to 3 million degree range and the densities vary from 108to 1010cm-3(Foukal, 1975; Krieger, 1977).
Kinematics of a System of Loop Prominences
Authors: Engvold O. , Jensen E. , Andersen B.N.
Published: July 2016

A detailed description of the development of loops connected with flares has been given by Bruzek (1964). Data on true mass motion as inferred from Doppler-effects are sparse in the literature as flare loop prominences are rare phenomena (Kleczek 1965). Jefferies and Orrall (1965) reported high velocities near the top of a loop system. Gurtovenko et al. (1969) observed large Doppler velocities in the loop system of July 11th. 1966.
The Onset of Coronal Transients
Authors: van Tend W.
Published: July 2016

Recently Anzer (1978) has discussed a model for the motion of transients in the high corona. In this model the transient is pictured as a circular current loop with a changing radius r, and having two fixed footpoints separated by a distance 2r0at the solar surface. The transient starts off with zero velocity at the point where r = r0. At that point however the acceleration, which is given by

is generally non-zero. In (1) M⊙is the solar mass; G is the gravitational constant; b (which equals a/4, where a was introduced by Anzer (1978)) is a constant on a short time scale, which however may change on a long time scale when mass or electric current is supplied to or lost by the system; f is a function describing the distribution of mass and magnetic flux, qualitatively displayed in Figure la; R is the distance of the top of the current circuit to the solar center; r2/R2as a function of R is shown in Figure lb.
On the Role of Chaos and Instability in the Evolution of Nonlinear Nonstationary Stellar Systems
Authors: Nuritdinov S.N.
Published: July 2016

The role of chaos and instability in evolution of nonlinear, non-stationary stellar system have been discussed. It is possible to distinguish between the only two different cases (i) strongly non-stationary stage when we have the violent relaxation accompanied by the compulsive mixing (ii) weakly non-stationary state or quasilinear case, when the quasidiffusion mixing takes place. In case (i), the chaos and chaotic motion g stars play very important role and in case (ii) the role of any type of instability is important.
Ergodity of the Motions in the Dynamical Systems with Two Degrees of Freedom
Authors: Agekian T.A. , Mylläri A.A. , Orlov V.V.
Published: July 2016

We study a process of stochastization of the motions in an example of the Henon-Heiles model. We propose a new method to study this process a method of the field of directions of motion in the meridional plane. A numerical integration of the equation for the derivative of this field ∂f/∂n to the normal to a trajectory has been made. We denote the points in which ∂f/∂n → ± ∞, and derive the contours of orbit and folds of directions. The growth of ergodity is connected with the increase of a number and an area of the folds. May be, a successive doubling of a number of folds takes place that results in a chaos. In the transition region we found a complex periodical orbit. The interpretation of this fact may be made as an example of cantori. A transition region has very small sizes about 10−4
Stability of Self-gravitating Finite Disks
Authors: Ambastha Ashok
Published: July 2016

Large scale, or “global” stability of finite radius, razor thin disk of self-gravitating matter in presence of a massive halo surrounding the disk is studied as an eigen-value problem. Effect of the halo mass and size on the allowed global spiral eigenmodes of the disk is discussed.
Unstable Triple Systems - Escape From Initial Configurations
Authors: Anosova J.P.
Published: July 2016

The statistical material obtained at the Leningrad observatory amounts to about 3, 104 tripe systems with negative total energy (Anosova and Orlov, 1985; Anosova 1986). From this material the basic qualitative results have been summarized.
The In-Plane Motion of a Geosynchronous Satellite Under the Gravitational Attraction of the Sun, the Moon and the Oblate Earth
Authors: Bhatnagar K.B. , Kaur Manjeet
Published: July 2016

The in-plane motion of a Geosynchronous satellite under the gravitational effects of the sun, the moon and the oblate earth has been studied. The radial deviation (Δr) and the tangential deviation (rcΔθ) have been determined. Here rc represents the synchronous altitude. It has been seen that the sum of the oscillatory terms in Δr for different inclinations is a small finite quantity whereas the sum of oscillatory terms in rcΔθ for different inclinations is quite large due to the presence of the low-frequency terms in the denominator.
Orbital Instability and Forming of Outer Part of Asteroidal Belt
Authors: Alfimova Elena V.
Published: July 2016

The orbital instability and forming of outer part of Asteroidal belt has been studied earlier in the Circular case. Here the same problem is studied in elliptic case.
Astrophysical Interesting Compound Grains Produced by a Gas Evaporation Method
Authors: Kaito C. , Saito Y.
Published: July 2016

Production methods of Fe3O4grain and MgS grain have been introduced. Fe3O4grain was produced in an Ar gas pressure range of 25 to 100 Torr by evaporating FeO powder. The growth of Fe3O4have been discussed as the result of oxidation of Fe grains. MgS grain produced by the reaction of Mg and S vapors grew in the coagulation of tiny cubic sulfide.
Laboratory Spectra of Amorphous and Crystalline Olivine: An Application to Comet Halley IR Spectrum
Authors: Blanco A. , Orofino V. , Bussoletti E. , Fonti S. , Colangeli L. , Stephens J. R.
Published: July 2016

Among the various silicates proposed as components of cosmic dust grains, olivine is considered one of the most likely materials. In this work we present the infrared spectra of three different types of olivine grains: crystalline, amorphous and synthetic (also amorphous). While the first and second sample derive from the same natural mineral, the third one has been prepared in the laboratory according to the relative cosmic abundances of the elements. The experimental data are used to fit the emission feature observed in the comet Halley spectrum between 8 and 13μm.Satisfactory results are obtained by using synthetic olivine mixed with a small amount (5%) of crystalline grains.
The Optical Properties of Interplanetary Dust
Authors: Lamy P.L. , Perrin J.M.
Published: July 2016

After briefly evaluating the observations of the Zodiacal Light and F-corona, we review the laboratory results on the light scattering by dust particles and the various theories which have been recently proposed. We then discuss the optical properties of the dust with emphasis on the phase function, the polarization, the color, the albedo and the local enhancement in the Gegenschein.
The Dust in the Coma of Comet Halley
Authors: Hage Joniek I. , Greenberg J. Mayo
Published: July 2016

The interstellar dust model of comets is numerically worked out to satisfy several basic constraints provided by observations of comet Halley and to derive the porosity of coma dust. The observational constraints are: (1) the strengths of the 3.4 μm and 9.7 μm emission bands; (2) the relative amount of silicates to organic materials; (3) the mass distribution of the dust. The results indicate that coma dust has a porosity in the range 0.93 < P < 0.975. Preliminary calculations concerning the observed linear polarization of comet Halley are presented.
Polarimetric Properties of Halley’s Dust
Authors: Sen A.K. , Deshpande M.R. , Joshi U.C.
Published: July 2016

Comet P/Halley was observed polarimetrically for seven nights in IHW and other continuum filters, during the pre and post perihelion passages. The polarimetric observations have been combined with the observations taken by other investigators, to get a complete picture of phase angle and wavelength dependence of polarization of comet P/Halley. Assuming Mie type scattering by cometary grains, the observed polarization data were fitted for a set of complex refractive indices which are (1.387, .032), (1.375, .040) and (1.374, .052) at .365, .484 and .684μm respectively.
Electrostatic Fragmentation of Irregularly Shaped Particles
Authors: Mukai Tadashi
Published: July 2016

An enhancement of the electrostatic stress forces due to the charge concentration on a position with small radius of curvature on the surface of irregularly shaped particle causes the fragmentation of fluffy particle more than expected for a spherical particle. This mechanism may act to produce “dust clusters” as detected in comet P/Halley by Simpsonet al.(1987) and also “dust swarms” near the Earth as reported in Fechtig(1982).
Velocity Distribution of Fragments in Collisional Breakup
Authors: Nakamura A. , Fujiwara A.
Published: July 2016

One of the key outcomes of collisional disruptions to the dust system is the velocity distribution of fragments. A series of laboratory impact experiments were carried out to obtain the mass-velocity and the position-velocity relation of the fragments by taking movie films, and films for tow impacts were completely analyzed.
Constraints on the Parent Bodies of Collected Interplanetary Dust Particles
Authors: Sandford S. A.
Published: July 2016

Samples of interplanetary dust particles (IDPs) have now been collected from the stratosphere, from the Earth’s ocean beds, and from the ice caps of Greenland and Antarctica The most likely candidates for the sources of these particles are comets and asteroids. Comparison of the infrared spectra, elemental compositions, and mineralogy of the collected dust with atmospheric entry models and data obtained from cometary probes and telescopic observations has provided important constraints on the possible sources of the various types of collected dust. These constraints lead to the following conclusions. First, most of the deep sea, Greenland, and Antarctic spherules larger than 100 μm are derived from asteroids. Second, the stratospheric IDPs dominated by hydrated layer-lattice silicate minerals are also most likely derived from asteroids. Finally, the stratospheric IDPs dominated by the anhydrous minerals olivine and pyroxene are most likely from comets. The consequences of these parent body assignments are discussed.
Off-Disk Implantation of Early Solar Wind Into A Planetesimal-Dust Cloud
Authors: Sasaki Sho
Published: July 2016

Off-disk implantation of ancient solar wind into a protoplanetary dust cloud can explain the present amounts of solar-type noble gases in gas-rich meteorites and Venus, even if the dust cloud is very opaque along its midplane.
Dynamics of the Gas in Spiral Galaxies
Authors: Roberts William W.
Published: July 2016

The dynamics of the gaseous component in disk-shaped galaxies is thought to play an important governing role in star formation, molecule formation, and the degree of development of spiral structure. The prospect that density waves and galactic shock waves are present on the large-scale has received support in recent years from a variety of observational studies. Large-scale shocks provide a most promising mechanism for driving star-forming and molecule-forming events on the scales of many kpc along spiral arms. Such shocks may also govern the kinematics and relative distribution of various galactic tracers. This is particularly apparent in M81 and other external spirals, because of our “bird’s-eye-view” perspective, and for the tracers of HI and CO in our own Galaxy. Comparison of the CO observations with model simulations based on the precepts of the density wave theory shows that these precepts are supported by several observational results.
Dynamical Effects in the Central Region of the Galaxy
Authors: Sanders Robert H.
Published: July 2016

For the purpose of this Paper, I will define the central region of the galaxy as being the inner four kiloparsecs. I make this definition for three reasons:

1) Outside of four kiloparsecs, the rotation curve for the galaxy is well-defined by the Schmidt disk model; whereas, inside four kiloparsecs, the effects of a central spherical component on the rotation curve become conspicuous. This inner spheroid is a dynamical component of the galaxy which is distinct from the disk and may be distinct from the extended halo component as well.

2) There is a conspicuous hole in the total gas density distribution inside 4 kpc.

3) High peculiar or non-circular gas velocities are observed within the inner 4 kpc; velocities ranging from the 53 km s-1of the so-called 3 kpc arm, to 165 km s-1in the molecular clouds within 300 pc of the center.

I will now discuss these points in some greater detail.
Early Evolution of Galaxies: Preliminary Results
Authors: Chiezel J. P. , Lazareff B. , Vigroux Laurent
Published: July 2016

This paper is a progress report on studies of coupled dynamical and chemical evolution of galaxies. We have focused our attention on the occurence of galactic hot winds. Such hot winds have been studied by Mathews and Baker (1971) for elliptical galaxies. Recently the detection of an iron X-ray emission line in clusters of galaxies give some support to their existence (Vigroux, 1977). On an other hand, the large radial flow in the galactic center might be explained by such hot wind. We shall present here a preliminary version of our evolution model and the results obtained for the early evolution of a 1.2 × 1012Mʘgalaxy.
Chemical Properties and Age of the Components of the Galactic Halo
Authors: Castellani Vittorio
Published: July 2016

What we call Population II is composed by the stars populating the halo of our Galaxy, for which one finds evidences for an underabundance in the heavy elements and/or for an evolutionary age as large as (roughly) 1010years. Similar star populations are at present recognized in the halo of other spyral galaxies, in elliptical galaxies as well as in smaller systems, such as the Magellanic Clouds and the so-called Dwarf Galaxies as the ones in Draco and in Ursa Minor. Then Population II looks like representing a very general constituent of present Universe.
Dynamical History of the Stars in Relation with Age, Kinematics, Abundances, Birthrate
Authors: Mayor M.
Published: July 2016

A large amount of work has been devoted to correlations between kinematic properties and spectral types in order to improve our knowledge of stellar populations in our Galaxy and hence to deduce its structure and evolution. The classical results will not be repeated in the present review paper. However, emphasis will be laid on the sometimes contested correlations between age, abundance, kinematic properties and position in the Galaxy.
Interaction between Intergalactic Medium and Galaxies
Authors: Saar E. , Einasto J.
Published: July 2016

There exist two basically different approaches to the explanation of the structure and the evolution of galaxies. The conventional one is to consider galaxies as isolated self-regulating systems. This approach is, of course, largely justified. To illustrate the essential independence of the properties of galaxies from their intergalactic environment, it is enough to compare the mean densities within galaxies (10-24gcm-3) to the mean cosmological density (≲10-29gcm-3).
The Effect of Stellar Mass on Kinematical Age Determination
Authors: Iwanowska Wilhelmina
Published: July 2016

It is believed that kinematical characteristics of a group of stars, as the velocity dispersion or the lag in rotation, change systematically with time. This kinematical evolution is widely used for the determination of stellar ages. In particular, velocity dispersion should increase with time owing to irregular galactic force field. A classical formula for the increase of stellar velocity v with the age τ
Introduction
Authors: Pecker Jean-Claude
Published: July 2016

1. Evolution of the modelling of the inside of the Sun, from “standard models” to the more empirical approach used now, and based on neutrino astronomy, solar sismology, and the interpretation of active phenomena. 2. New concepts introduced in the set of physical equations valid inside the Sun, under the pressure of new observations. 3. Similar trends seeming to affect in a comparable way the modelling of the solar cycle. 4. Other stars, and the improved knowledge of solar evolution may help to understand many observed features of rotation, magnetism, etc...Conclusion: the Sun is “one”, - and it cannot safely be studied piecemeal.
Cataclysmic Variables as Binary Stars: Then and Now
Authors: Kraft Robert P.
Published: July 2016

A brief history is given of the clues that led to the establishment, in the period c. 1950 to 1965, of a universal binary model for novae and related cataclysmic variables. The observational facts, established early in this period by A. H. Joy and R. F. Sanford (selected binary orbits), J. L. Greenstein (spectroscopy) and M. Walker (photometry) are reviewed, as are the theoretical ideas that formed the basis for the early models, viz., those of G. Kuiper (restricted 3–body problem), A. Sandage and M. Schwarzschild (stellar evolution), J. Crawford (“dog-eat-dog” hypothesis), F. Hoyle and H. Bondi (accretion), S.-S. Huang (angular momentum losses), and S. Chandrasekhar (gravitational radiation). Some comparisons are made between “what we knew then and what we know now.” With apologies to all, the speaker will recall some anecdotes of an earlier time and comment on developments of the past score of years from a very personal perspective.
Classical Novae: Properties between Outbursts
Authors: Warner Brian
Published: July 2016

With the recent publication of Classical Novae, edited by Bode and Evans, there is no need for me to give a list of novae or their overall characteristics. Furthermore, probably the most interesting developments in the past few years in studies of novae during quiescence have been in those areas (magnetic systems, long term brightness variations) which are reviewed separately at this conference. So that leaves me with the task of making some general comments about recent trends in the more mundane aspects of quiescent novae. However, what may at first sight seem mundane often has importance to theoretical interpretation.
Strong Magnetic Fields in Nova Systems
Authors: Stockman H.S. , Schmidt G.D.
Published: July 2016

The discovery of variable circular polarization in V1500 Cygni (the remnant of Nova Cygni 1975) is the strongest evidence for the presence of highly magnetic white dwarfs in nova systems. If interpreted in terms of diluted cyclotron emission from a hot accretion shock, the recent observations of Schmidt and Stockman (1990 preprint, Ap. J. 1991) of the color dependence of the circular polarization can provide a empirical lower-limit to the primary’s magnetic field strength of B > 25 × 106 gauss. Such a field strength is comparable to those observed in other magnetic variables, thus providing support for the general picture of the current and pre-nova system and the explanation for the observed search-light and period changes following the eruption. Schmidt and Stockman have also measured lengthening of the polarimetric period indicating that the system will be resynchronized within a few centuries and well before the next nova eruption. This is an independent confirmation of a significant magnetic moment for the white dwarf primary.
The UV Luminosity of Old Novae
Authors: Selvelli P.L. , Cassatella A. , Bianchini A. , Friedjung M. , Gilmozzi R.
Published: July 2016

About 16 old novae are accessible to IUE, but only five (RR Pic, V 603 Aql, HR Del, DQ Her, and GK Per) have been observed in the ultraviolet and studied in any detail. Considering that, because of selection effects, only few and the brightest objects have been observed, it not possible to draw general conclusions on the UV luminosity LUVand mass accretion rates Ṁaccof old novae. We plan to improve the rather poor statistic by observing in the near future all objects falling above the IUE detection limit of m(V) ≃ 15 (i.e. X Ser, DK Lac, DN Gem, and HR Lyr). In the following we present preliminary results for 7 old novae observed with the IUE satellite whitin our observing programmes or obtained from the IUE archive.
New Infrared Results for Classical Novae
Authors: Gehrz Robert D.
Published: July 2016

Recent infrared studies of classical novae are described. The nucleation and growth of dust in nova ejecta was confirmed by optical/infrared photometry of several novae during the past five years including QU Vul, V842 Cen, V827 Her, and QV Vul. These novae provided evidence that dust of every astrophysical chemical and mineral composition can condense in nova ejecta. Infrared forbidden fine structure lines were identified in the recent novae V1819 Cyg, QU Vul, OS And, and V827 Her. The implication of IRAS measurements for nova energetics is discussed.
Recent and Future X-ray Observations of Classical Novae During the Outburst Stage
Authors: Ögelman Hakki
Published: July 2016

The discovery of soft X-rays from Nova GQ Mus with the EXOSAT satellite has added an important channnel to the observational information on classical novae during the outburst stage (Ögelman, Beuermann, and Krautter 1984). With peak luminosities in excess of 1038 erg s−1 and total liberated energies of more than 1045 erg, novae constitute the second most energetic outburst phenomena in the galactic population exceeded only by supernovae (see Gallagher and Starrfield, 1978; Truran, 1982 for a review of the observations and theory). Regardless of the details of the outburst, objects of the size of white dwarfs (~ 109 cm) radiating close to Eddington luminosities (~ 1038 erg s−1 ) should emit soft X-rays provided that the envelope is sufficiently transparent. In addition, the ejected shell, moving at velocities around 1000 km s−1, is capable of shocking the circumstellar medium to X-ray temperatures.
The Peculiar Slow Nova X Serpentis
Authors: Duerbeck H.W. , Seitter W.C.
Published: July 2016

The very slow nova X Ser (t3 = 555d), situated at a large distance from the galactic plane (z ≈ 4kpc), reached maximum light at 9m in May 1903. It was discovered 5 years later on a Harvard plate (Leavitt 1908). No outburst spectrum is known. A photographic outburst light curve is given by Walker (1923); additional photometric data were published by Sakharov (1954) and Kinman et al. (1965). The light curve, shown in Fig. 1, presents 10-day means, based on all published data, and unpublished data taken from Emily Hughes Boyce’s notebook, Harvard College Observatory Plate Collection.

Hughes Boyce (1942) discovered a 275d periodicity during minimum light. From the fragmentary light curve in Fig. 1, including three more recent ‘oscillation’ maxima, a period of 277 days is found. If one assumes that the nova reached Mpg = −6 at maximum, the typical value for a slow nova, the mean absolute magnitude at minimum, Mpg = +2, together with the observed amplitude of about 2m and a relatively long mean period, suggests a very late-type (typically M6e) semi-regular variable.
Chemical Composition of Nova Centauri 1986
Authors: de Freitas Pacheco J.A. , Dell'Aglio R. , Costa D. , Codina-Landaberry S.J.
Published: July 2016

We have obtained extensive spectroscopic observations of Nova Cen 1986 at different phases of the event.

From the observed Hα/Hβ line ratio we derived a colour excess EB-V = 0m.54. Using the empirical relationship between the fading time and the absolute magnitude at maximum light as well as the width of the Nal interstellar lines, we estimated for the nova a distance of 1.2 ± 0.2 kpc. The full-width of non-blended lines at the nebular phase indicates an expansion velocity of 1400 ± 120 km s−1

The temporal behaviour of the Hβ emission suggests that the electron density varies with time as Ne ∝ t−3, i.e., the shell evolves more or less homologously. The electron temperature was estimated from the [NII] and [OIII] line ratios. In the O+2 region the electron temperature is in the range 14100 ± 1200 K. The N+ region has a lower temperature, T ≃ 8000 K around day 142 after maximum light. The N+ temperature increases in this region as the shell evolves and attains the same values observed in the O+2 region around days 300-470.
Novae Between Outbursts
Authors: Livio Mario
Published: July 2016

The paper is divided into two parts. In the first part, the common envelope phase that follows a nova outburst is discussed. It is shown that this phase leads to mass loss, preferentially in the orbital plane. It is argued, that the common envelope can explain the rapid appearance of a nebular spectrum in novae and the shaping of the nebula.

In the second part, the present status of the cyclic-evolution (“hibernation”) scenario is reviewed. It is argued that novae and dwarf novae are the same systems, transforming from one class to the other. Observational and theoretical evidence is presented, that shows that both the accretion rates and the white dwarf masses in observed nova systems should be higher than the average. Novae should therefore not be regarded as “typical” cataclysmic variables. Some critical observations that can provide observational tests are suggested.
Accretion on CO White Dwarfs. Influence of the External Burning Shells on the Evolution
Authors: Hernanz M. , José J. , Isern J.
Published: July 2016

The influence of accretion in the evolution of CO white dwarfs is calculated, up to the thermonuclear runaway, with a previous analysis of the H-He burning shell. For this later study, a two-zone model is developed, consisting of two thin shells in plane-parallel approximation. The influence in the inner core evolution is discussed.
Herbig-Haro Objects
Authors: Böhm K.H.
Published: July 2016

The available observational information on the geometrical structure, emission line and continuous spectra, line profiles, radial velocities and linear polarization of Herbig-Haro objects is briefly reviewed. We emphasize the inhomogeneous structure of the “classical” Herbig-Haro objects and the appearance of small “condensations” with radii of ~300-900 a.u. The apparent paradox of the presence of “gaseous nebula type” as well as “reflection type” Herbig-Haro objects is discussed.

A purelyempiricalmodel of the regions of line formation is discussed. It shows that regions of low density (Ne~103cm-3) cover the space between the condensations and most of the volume of the condensations themselves. Only between 0.1 and 1% of the volume of the condensations is covered by a high density medium (Ne~ 4 x 104cm-3, N ~105cm-3) which, however, contributes very strongly to the formation of the spectrum.

Differenttheoretical modelsfor the line forming regions are discussed. We strongly favor the shock wave theory in which the emission lines are formed in the cooling regions of (running) shock waves. The general agreement between observations and the new calculations by Raymond is emphasized, and the few remaining discrepancies are discussed. The possibilities of explaining other properties of Herbig-Haro objects (including time scales, sizes and filling factors of condensations) are described.
Flare Stars in Stellar Aggregates
Authors: Mirzoyan L.V.
Published: July 2016

After the report on flare stars presented by Ambartsumian and the author (1971) at the last Bamberg Colloquium, some success has been achieved in the study of these interesting objects.

Optical observations of stellar flares with high time-resolution undoubtedly proved the explosive character of this phenomenon and the non-thermal nature of the radiation that appears at least at the beginning of the flare. Parallel optical and radio observations of flares in stellar aggregates complicated the interpretation and showed how far we are from an understanding of the physical nature of this phenomenon. Finally, new optical observations of stellar flares in aggregates of different age confirmed the evolutionary significance of this stage in the life of a star and led to the study of certain regularities in the evolution of flare stars.
The Interaction of A Nova with its Circumstellar Envelope
Authors: Malakpour I.
Published: July 2016

The existence of dusty envelopes around novae is shown by various authors using different methods:

We have used the Balmer decrement of novae. In the case of all novae a sudden variation of this decrement is observed a certain time after the beginning of the outburst, the Hα/Hβ ratio rising from its normal value to a maximum and then decreasing again to its normal value.
The Galactic Distribution of OH/IR Stars
Authors: Habing H.J.
Published: July 2016

In 1967 Wilson and Barrett (1968, 1970) discovered that some long period variables, very red and apparently very late type stars, emit OH microwave line emission that is especially strong in the 1612 MHz line at 18 cm. At present some 65 such OH-emitting stars have been identified - for a recent compilation see Bowers and Kerr (1977, M giants) and Baudry et al. (1977, M supergiants). Several stars show maser emission in H2O and SiO as well. At this colloquium Winnberg will review the present status of our knowledge of these stars.
OH/IR Stars Near the Galactic Centre
Authors: Baud B.
Published: July 2016

Observations at 1612 MHz around the Galactic Centre have revealed the existence of 43 OH/IR stars. Sources within 6° longitude from the Galactic Centre appear to be associated with the central parts of the Galaxy. They have a large velocity dispersion and a mean radial velocity of 0 km s−1, indicating that there is no net rotation around the Centre. Within 2° from the Centre there is a strong relative increase in the number of sources with a velocity separation between the two emission peaks of less than 30 km s−1. This is discussed in terms of a possible interaction between the circumstellar shell and the ambient medium.
The Metal-Rich RR Lyraes: Their Origin and Bearing on the Age and Helium Abundance of the Galactic Disk
Authors: Kraft Robert P.
Published: July 2016

We consider further the question of the origin and evolution of metal-rich RR Lyraes (MR-RR’s) in the solar vicinity, continuing the discussion begun by Taam, et al (1976) who showed that MR-RR’s descend from red giants of Eggen’s old disk population. If an old disk giant (ODG) is similar to a giant in a galactic cluster like NGC 188, then it must lose~0.5 M⊙ if it is to pump the HR-RR domain; thus the probability that an ODG will metamorphose into an RR Lyrae is about 1/200th the probability that its metal-poor (halo) counterpart will do so, else the sky would be full of bright MR-RR’s.