bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronic Band and its Implication in the Cometary Dust
Authors: Watanabe Jun-ichi , Nishioka Kimihiko
Published: July 2016

The unique morphology of the synchronic band in the cometary dust tail is explained by finite-lifetime fragment model (Nishioka and Watanabe, 1990). However, this model needs a severe restriction on the lifetime of the dust fragments;25-70 days (r = 1 A.U.). This implies that detailed analysis of the synchronic band may reveal physical properties of the cometary dust particles. In this paper, we suggest that the fragments in the synchronic band are relatively pure ice if they are not organic grains.
Penetration of Hypervelocity Projectiles into Low Density Materials
Authors: Fujiwara A. , Kadono T. , Nakamura A. , Ishibashi T. , Fujii N.
Published: July 2016

Spherical nylon projectiles of 7mm diameter and up-to 4km/s velocities were penetrated into three types of targets; aluminum multisheet stacks, foamed polystyrene, and 1-atm air. Penetration depth, recovery rate of the projectiles were determined as a function of projectile velocity and target density, and a new type of dust collector is proposed.
An Estimation of Meteoroid Flux at Outer Martian Space for Steady Meteor Streams
Authors: Nagasawa Ko
Published: July 2016

This work was done to estimate meteoroid fluxes of steady meteor streams at places far away from the sun, for example, beyond Martian orbit. For the estimation, a Normal Distribution Model is introduced. This model assumes that the flow of meteoroids is steady and the meteoroids are distributed in the form of a normal distribution around the orbit of their parent comet. Keplerian motion of each meteoroid is also assumed. Some parameters, necessary for determining a practical model, can be obtained through observations. The model will give the overall structure of meteor streams and their fluxes can be calculated for any points on the orbits of their parent comets. Calculations show that fluxes of streams sharply decrease as the solar distance increases and that meteoroids scatter chiefly along the orbital planes of the parent comets. The model seems to be useful to deduce rough structure of meteor streams.
Mass Distribution and Bulk Density Distribution of Interplanetary Dust
Authors: Hajduk A.
Published: July 2016

Mass distribution of the interplanetary dust is reexamined taking into account bulk density distribution of the dust and larger particles. It can be shown that the mass index of particles depends on the evolutionary stage of the population and changes along the mass scale. The flattening of the mass distribution at the higher mass range may explain the problem of the equilibrium between the source and sink of the interplanetary dust.
The International Meteor Organization
Authors: Gyssens M. , Knöfel A. , Rendtel J. , Roggemans P.
Published: July 2016

Founded in 1988, the International Meteor Organization (IMO) is an international scientific non-profit association with members all over the world. The IMO was created in response to an ever growing need for international cooperation of amateur work. As such, the main objectives of the IMO are to encourage, support and coordinate meteor observing, to improve the quality of amateur observations, to make global analyses of observations received world-wide, to develop contacts between amateurs and professionals, and to disseminate the observations and results obtained to other amateurs and to the professional community.
Physical Processes on Circumplanetary Dust
Authors: Burns Joseph A.
Published: July 2016

The life cycles of grains in circumplanetary space are governed by various physical processes that alter sizes and modify orbits. Lifetimes are quite short, perhaps 102-104years for typical circumplanetary grains of 1 micron radius. Thus particles must be continually supplied to the circumplanetary complex, probably by the grinding down of larger parent bodies in collisions. Dust is eroded gradually through sublimation and through sputtering by the magnetospheric plasma but also is catastrophically destroyed through hypervelocity impacts with interplanetary micrometeoroids. Orbits evolve through momentum transfer (light drag, plasma or Coulomb drag, and atmospheric drag), and through resonant gravitational and electromagnetic forces. Plasma drag is generally the most effective evolution mechanism, with the possible exceptions of exospheric drag at Uranus and of electromagnetic schemes for some conditions. Since grains become charged (with typical electric potentials of a few volts), they undergo associated orbital perturbations: variable electromagnetic forces can cause the systematic drain of energy (orbital collapse) or, at specific (resonant) orbital locations can force large orbital inclinations/eccentricities. Solar radiation induces a periodic orbital eccentricity that can reach substantial values for 1 micron particles distant from the giant planets.
Reading Saturn’s Ring Spokes
Authors: Doyle Laurance R. , Grün Eberhard
Published: July 2016

The micron-sized dust forming the radial spoke-like features in Saturn’s rings are studied using radiative transfer analysis. Theories for their likely origin and evolution are discussed in light of these results, and future work is outlined.
Jets of Fragments from Catastrophic Break-up and their Astrophysical Implications
Authors: Martelli G. , Rothwell P. , Smith P.N. , Giblin I. , Martinsson J. , Ducrocq E. , Wettstein M. , Martino M. Di , Farinella P.
Published: July 2016

We present some preliminary results of a series of catastrophic break-up experiments carried out in the open, against targets of natural and artificial rock, with and without a harder core. These experiments were aimed at investigating the outcomes of hypervelocity impact disruption phenomena, designed to understand the influence of large-scale collisions on the evolution of asteroids and other small solar system bodies. For the first time in this kind of experiments, evidence was found of collimated jets, i.e. the ejection of a statistically significant number of fragments all closely aligned about some preferential planes. Moreover, the presence of some groups of fragments lying close to each other on the ground was also detected.
Cometary and Asteroidal Sources of Interplanetary Dust
Authors: Sykes Mark V.
Published: July 2016

The Infrared Astronomical Satellite has provided extensive observations of the zodiacal cloud at high spatial resolution which will not be matched in the forseeable future. Within the zodiacal cloud, IRAS discovered extended dust structures providing the link between the interplanetary dust complex and the asteroids and comets which are its source. These are the asteroid dust bands and the cometary dust trails.
Formation of Spiral Galaxies
Authors: Larson Richard B.
Published: July 2016

Conventionally, two major components of spiral galaxies are distinguished: (1) a “spheroidal component”, which includes the central bulge and the surrounding halo, and (2) a “disc component”, which is basically flat and circular but is often warped at the edges. Other structures, such as bars or rings, may also be present, but they are probably of less fundamental significance for the processes of galaxy formation, and therefore they will not be considered here. The distinction between bulge and disc components corresponds approximately to the classical distinction between Population II, as exemplified by the globular clusters which have a nearly spherical distribution, and Population I, which is confined to the galactic plane and is relatively young and metal-rich. However, unlike the “classical” Population II objects which are old and metal-poor, the inner part of the bulge of our galaxy and of other galaxies is in fact metal-rich, and may even contain some young stars.
Gravitational Separation of Elements During Certain Stages of Galactic Evolution
Authors: Basinska-Grzesik Ewa
Published: July 2016

Heavy metal content is, apart from the kinematical behaviour, one of the important parameters of the population characteristics of stars. Spectroscopic observations of some galaxies including our own give the evidence for the gradient of heavy elements abundances towards the galactic center and the galactic plane (Peimbert 1975, Van den Bergh 1975 review papers). Simultaneously several authors (Kuroczkin 1974, Khokhlova 1976) found that the deficiency (or enrichment) increase with the mass number of the element.
A Model for a Two Component Galaxy.
Authors: Caimmi R. , Dallaporta N. , Secco L.
Published: July 2016

As most of today approaches to the problem of galactic structure are based on the consideration of the two main components of a galaxy, halo and disk, it was thought that even simple models of such kinds of double structures, based only on the application of general theorems, could be of some use, at least for simplified outlooks concerning galac tic evolution. With this aim in mind, we have undertaken the treatment of bodies constituted by two different axially deformed polytropic structures, homocentrical and coaxial, with arbitrary values for the two masses MIand MII, the two radii aIand aIIof the undeformed objects (aIaII) and polytropic indices nIand nII, interacting with each other only gravitationally. The flattening of the spheroids is assumed to be due to solid body rotation and tidal interaction, and the treatment follows closely the method used for such single structures by Chandrasekhar and Lebovitz.
Spectral Line Observations of the Galactic Centre Region
Authors: Davies R. D. , Cohen R. J.
Published: July 2016

An investigation of the central regions of the Galaxy has been made with an angular resolution of ~10 arcmin with the radio telescopes at Jodrell Bank using the spectral lines of HI (λ21 cm), OH (λ18 cm) and H2CO (λ6 cm). Observations of radio recombination lines in the range (λ21 to 125 cm) have also been taken. These data taken together provide information on the velocity field and gas distribution in the galactic centre region. A continuing programme of spectral line observations of the galactic centre is being pursued at Jodrell Bank.
Observational Constraints for the Chemical Evolution of the Solar Neighbourhood
Authors: Grenon M.
Published: July 2016

The basic material for this preliminary investigation is formed of the Northern stare of Gliese’s catalogue, completely measured down to the K5 spectral type in the Geneva system. The physical properties and new spatial velocities are derived and, after removal of non members of the local sphere, 230 stars can be used here.
A Composition Gradient in the Galactic Disk
Authors: Janes K. A.
Published: July 2016

A number of recent investigations have demonstrated that the heavy element abundance in galactic disks decreases with increasing distance from the center. Although there is little question that the composition in the outermost parts of galactic disks differs from that in the inner regions, the precise nature of the presumed gradient in our own galaxy remains undetermined. At the present time, the most specific evidence for a gradient is based either on kinematics of stars in the solar vicinity (e.g., Janes, 1975 or Mayor, 1976) or on observations of distant H II regions (Hawley, 1977) and planetary nebulae (Peimbert, et al, 1977). Little is known about the variation of abundance ratios with position or the relation between stellar ages and the composition gradient. However, all three of these quantities (that is, the overall metallicity gradient, variation of abundance ratios and stellar age effects) can now be estimated from theoretical models of galactic evolution (for example, see Tinsley and Larson, 1977).
Some Regularities in Chemical Composition of Unevolved Main Sequence Stars and Synthesis of the Elements
Authors: Khokhlova V.L.
Published: July 2016

The published data on chemical abundances derived from fine analysis for about 80 G, F and A main sequence stars are analysed. The following conclusions are drawn :
The Cosmogonical, Significance of the Z Distribution of Stars
Authors: Balazs L.G.
Published: July 2016

According to the consequences of the density wave theory of spiral structure a shock wave is triggered in the interstellar gas leading to the formation of new stars (Roberts, 1969). The space and velocity distribution of the newly born stars is similar to those of the diffuse material which they have been formed from, i.e. they are strongly concentrated to the Galactic plane and have nearly circular velocities and small velocity dispersions. The velocity dispersions could increase in course of time by different stellar dinamical processes: encounters with large clouds of stars and gas (Spitzer and Schwarzschild, 1953; Julian, 1967; Barbanis and Woltjer, 1967), cooperative phenomena (Lynden-Bell, 1967), effect of non periodic orbits (Wielen, 1975), etc. If some of this processes has a time scale comparable with the time the star streeming needs between two consecutive passages of the density wave one expects an observable effect in the space distribution of A and late B type stars perpendicular to the Galactic plane. The Δt time difference between two consecutive passages equals 2.5×108 years near the sun. If the lifetime of stars is greater than this value their space distribution is a superposition of newly born stars with small velocity dispersion and stars born earlier and having greater velocity dispersion already. (Fig. 1.)
Final Remarks: Connections between Chemical and Dynamical Evolution
Authors: Tinsley Beatrice M.
Published: July 2016

Dynamical processes strongly affect the chemical enrichment of gas in galaxies, so abundances in stars and the Interstellar medium can be used as probes of the dynamical history of the Galaxy. By way of tying together some diverse points, rather than summarizing the conference, I shall discuss some examples of connections between chemical and dynamical evolution. The first section of this paper mentions some of the well-known ways in which dynamical processes can affect chemical evolution, in order to outline a theoretical background to the use of abundances as clues to dynamics.
On the Accuracy of Solar Modelling
Authors: Turck-Chièze S.
Published: July 2016

The confrontation between theoretical predictions and observations requires an estimate of the uncertainties of these predictions. Recent results on nuclear reaction rates and photospheric abundances are analysed, in a classical model framework. The role of opacities in the determination of the helium content, the neutrino fluxes prediction and the adiabatic sound speed is discussed. Comments on extra phenomena as mass loss, turbulent mixing and WIMPS are also presented, in the light of very recent seismological results.
Solar Neutrino Projects
Authors: Spiro M. , Vignaud D.
Published: July 2016

An overview of the solar neutrino projects is given, with an emphasis on the complementarity of the different experiments (gallium, indium, heavy water,...) to solve the solar neutrino problem that was raised by the chlorine and the Kamiokande results. The separation of the different sources of neutrinos in the Sun would contribute significantly to the astrophysical understanding of the Sun. Some of the planned experiments could be able to pinpoint neutrino oscillations (within a wide range of parameters) almost independently of solar models. Projects which are particularly sensitive to a variation of the neutrino flux with time are also discussed.
Report on the Homestake Chlorine Solar Neutrino Experiment
Authors: Davis R. , Lande K. , Lee C.K. , Cleveland B.T. , Ullman J.
Published: July 2016

A report on the results obtained from the chlorine radiochemical solar neutrino experiment in the Homestake mine, Lead, SD. Over the period 1970-1988 a neutrino capture rate of 2.3 ± 0.3 SNU was observed. This rate is discussed in relation: to the theoretical standard solar model, the results from the Kamiokande II experiment, and variations in the solar neutrino flux.
Matter Effects in Neutrino Propagation
Authors: Smirnov A. Yu.
Published: July 2016

Conditions and dynamics of the resonant neutrino conversion are described. We discuss the applications of the effect to the solar neutrinos as well as present status of the conversion inside the Sun. The influence of different matter density perturbations on the conversion is considered, and in this connection the possible effects of parametric and stochastic enhancement of the influence are remarked.
Recent Helioseismological Results from Space: Solar p-mode Oscillations from IPHIR on the PHOBOS Mission
Authors: Fröhlich C. , Toutain T. , Bonnet R.M. , Bruns A.V. , Delaboudinière J.P. , Domingo V. , Kotov V.A. , Kollath Z. , Rashkovsky D.N. , Vial J.C. , Wehrli Ch.
Published: July 2016

IPHIR (Interplanetary Helioseismology by IRradiance measurements) is a solar irradiance experiment on the USSR planetary mission PHOBOS to Mars and its satellite Phobos. The experiment was built by an international consortium including PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel sunphotometer (SPM) which measures the solar spectral irradiance at 335, 500 and 865 nm with a precision of better than 1 part-per-million (ppm). It is the first experiment dedicated to the investigation of solar oscillations from space. The results presented here are from a first evaluation of data gathered during 160 days of the cruise phase of PHOBOS II, launched on July, 12th 1988. The long uninterrupted observation produces a spectrum of the solar p-mode oscillations in the 5-minute range with a very high signal-to-noise ratio, which allows an accurate determination of frequencies and line shapes of these modes.
Helioseismic Investigation of Solar Internal Structure
Authors: Christensen-Dalsgaard Jørgen
Published: July 2016

The solar oscillation frequencies provide our only means of obtaining detailed information about conditions inside the Sun. Here I give a brief overview of the relevant properties of solar models and solar oscillations, and present examples of the dependence of the oscillation frequencies on the structure of the model. Furthermore I discuss some results obtained so far from analysis of observed frequencies.
Stellar Seismology
Authors: Däppen Werner
Published: July 2016

Stellar acoustic oscillation frequencies will likely be accurately observed in the near future, in analogy to the well-known solar five-minute oscillation frequencies. Of course, we will never expect the wealth of solar data, which is a result of spatial resolution. We will therefore not be able to solve the inverse problem, that is to probe physical quantities as functions of depth, and the low number of anticipated observed frequencies will make an unambiguous mode identification difficult. Despite this restriction to the forward problem, however, observed stellar oscillation frequencies will become valuable constraints for the determination of stellar parameters. One should not forget that the present knowledge of stellar ages and compositions relies on the calibration of theoretical models (matching effective temperature and luminosity). Additional observational constraints will improve these calibrations, even if the theoretical models themselves are not questioned. We hope, however, that the observation of stellar oscillation frequencies will also lead to improvements in the physics of stellar models, in analogy to the solar case. Again, of course, stellar seismologists will be less ambitious than helioseismologists, since there are more open parameters in stellar models. However, stellar observations will allow tests of models with different age and composition.
Angular Momentum Transport and Magnetic Fields in the Solar Interior
Authors: Spruit H.C.
Published: July 2016

The possible mechanisms of angular momentum transport in convectively stable regions of a star are reviewed, with emphasis on transport by magnetic torques. The strength and configuration of the field in such layers is quite uncertain, because it is not known if the field can reach a dynamically stable configuration. A lower limit to the field strength is obtained by assuming that the field is always dynamically unstable, and decaying at the (rotation modified) dynamical time scale. The present field in the sun would then be of the order 1G, with poloidal and toroidal components of similar strength. The differential rotation in the core, if due only to the solar wind torque, would be very small for this field strength, and instead would more likely be governed by magnetic coulpling to the differential rotation of the convection zone. If small scale hydrodynamic transport mechanisms are present, their properties would also be influenced by a field of this strength.
Galactic Distribution and Outburst Frequency of Classical Novae
Authors: Duerbeck Hilmar W.
Published: July 2016

The observed rate and spatial distribution of galactic novae can be explained with the concept of two nova populations, the disc novae of faster outburst development, and the slower bulge novae. Similar populations seem to exist in nearby galaxies. The space density of galactic novae depends strongly on the recurrence time, which is unknown and may lie between 500 and 20 000 years. If the recurrence time is long, the population of quiescent novae must be identified; the hibernation scenario may or may not be a solution.
Novae in Clusters and Galaxies
Authors: Shara Michael
Published: July 2016

My main goal in giving this review is NOT to induce hibernation in the audience. Rather, it is to survey the known cases of erupting classical novae in open and globular clusters, and galaxies external to the Milkey Way. More important, I want to emphasize what these novae in stellar systems can teach us about nova eruptions. In my conclusions I will make a few brief remarks about what we might hope to know about classical novae by the time IAU Symposium #222 occurs (by then Space Telescope will hopefully have been in orbit and producing scientific results for many years!). References to older works may be found in the reviews of Trimble (1980) and Webbink (1980).
CP Puppis: Another V1500 Cyg?
Authors: O’Donoghue D. , Warner B. , Wargau W. , Grauer A.D.
Published: July 2016

As first pointed out by Warner (1985), the overall properties of CP Pup and V1500 Cyg are very similar: both were very fast, very large amplitude novae with ~ 0.3 mag photometric humps at roughly the orbital period. Neither variation is strictly periodic (Patterson 1979; Warner 1985). Variable circular polarization (with period slightly different from the orbital period) has been found in V1500 Cyg showing that its white dwarf is strongly magnetic and has broken synchronism with the secondary star (Stockman, Schmidt & Lamb 1988). In contrast, no circular polarization has been found in CP Pup. Nonetheless, does the slight difference between the photometric and spectroscopic periods indicate it is also a magnetic system (Warner 1985; Bianchini et al. 1985a)?

New photometric and spectroscopic data for CP Pup are reported which resolve the aliases and confusion in the periods found by Bianchini et al. (1985a,b), Warner (1985) and Duerbeck et al. (1987) and allow an examination of the evidence for its magnetic nature.
Chemistry of Nova Envelopes
Authors: Boyarchuk A.A. , Antipova L.I.
Published: July 2016

Novae form a very interesting class of non-stationary objects. A considerable amount of observational data, both photometric and spectroscopic, covering different stages of nova outbursts, have been stored up by observers for many years. Processing and systematization of these data has lead to a better understanding of the physical processes taking place in the nova outbursts.

The first spectra of novae at maximum brightness proved to be similar to the spectra of supergiants; their distinctive feature was the presence of the strong lines of lines from C, N and O (McLaughlin, 1936). This fact lead to suspect that these elements must be overabundant in the nova envelopes.
Multi-wavelength Observations of Novae in Outburst
Authors: Starrfield S.
Published: July 2016

A nova outburst is the second most violent explosion that can occur in a galaxy. While less violent than a supernova explosion, novae are considerably more frequent. More than 250 have been observed in the last century and there were more than a dozen novae being observed in outburst when this review was written. Over the past few years they have been studied at wavelengths ranging from the radio to the X-ray and these data have provided exciting new information about the nova outburst. For example, IUE studies have shown that there are two classes of novae; those that occur on carbon-oxygen white dwarfs and those that occur on oxygen-neon-magnesium white dwarfs. EXOSAT observations have shown that an intense X-ray emitting source exists in the system for years after the initial outburst has been discovered and radio studies have found that some novae are ejecting material in jets. IR studies have found high excitation coronal lines, dust formation, and have provided accurate distances. Optical studies have provided determinations of densities and temperatures in the ejecta and have discovered a class of novae that occur on strongly magnetized white dwarfs. There have been predictions but no detections of γ-ray emission. Finally, novae are time dependant and simultaneous or contemporaneous observations are required in order to learn as much as possible about the characteristics of the outburst.
Simultaneous Optical and UV Spectra of the Two LMC Novae 1988
Authors: Drechsel H. , Andreae J. , Starrfield S. , Sonneborn G.
Published: July 2016

The two classical novae of 1988 in the LMC are the first extragalactic novae, which have been studied in the UV range. IUE spectra were taken under the Nova Target of Opportunity program, and quasi-simultaneous optical spectra were obtained by the authors. The spectral development in the UV and visual ranges is discussed for both objects.
An Hα Image of Nova V1500 Cygni Twelve Years After Outburst
Authors: Wade Richard A. , Ciardullo R. , DeVeny J.B. , Jacoby G.H. , Schoening W.E.
Published: July 2016

We obtained a narrow band Hα image of V1500 Cyg during an engineering run at the R-C focus of the KPNO 4 m telescope on UT 1987 July 19. Our detector was an 800 × 800 format TI CCD, which yielded a plate scale of 0.1013 arcsec/pixel. The exposure was 2000 sec and was made through a 75 Å wide filter centered at 6563 Å. The seeing was ~ 1.2 arcsec.

Our reductions were accomplished with the DAOPHOT photometry package (Stetson 1987) and IRAF data reduction facility. After performing standard bias level subtraction and flat field division, we used DAOPHOT to find the frame’s normalized point spread function (PSF) by summing the images of several field stars. We then scaled the PSF to calculate the instrumental magnitudes of the stars and of V1500 Cyg. This procedure overestimates the brightness of the nova, since the nebula contributes extra light to the central object and modifies the expected intensity distribution. (This is especially true in the narrow Hα bandpass.) Hence, in a frame where the PSF has been used to remove the fitted images, all the stars have satisfactorily small residuals around the mean sky level, except the nova itself. The image of V1500 Cyg shows sky level at the center, but a halo that rises from the center and then falls away.
Ultraviolet spectroscopy of the shell of RR Pic
Authors: Duerbeck H. W. , Seitter W. C. , Bode M. F. , Evans A.
Published: July 2016

Spectroscopy of the nebular (as opposed to the stellar) remnants of old novae can be a powerful diagnostic of physical conditions in, and mode of excitation of, nova shells. While optical spectroscopy of nova shells has been widely used in this way, few are sufficiently well resolved, and sufficiently bright, to be observed with IUE.

Combined optical and ultraviolet spectroscopy of only two nova remnants–those of GK Per and DQ Her–have been reported to date. Ferland et al. (1984) demonstrated that the shell of DQ Her is extremely cool (Te ≃ 500 K) and is excited by a hot central source. Bode et al. (1988) showed that the ultraviolet and optical lines in the spectrum of the GK Per nebula can best be understood in terms of shock excitation, consistent with its observed properties at radio wavelengths (Seaquist et al. 1989).
The Ionization of Novae Ejecta
Authors: Williams R.E.
Published: July 2016

Novae ejecta pass through four distinct phases of evolution of the emission-line spectrum, caused by different ionization characteristics of the shell. These include a neutral (I), an auroral (II), a coronal (III), and a nebular (IV) phase. Photoionization from the contracting photosphere of the hot white dwarf is the source of the ionization, including the highly ionized coronal phase. Changing emission line ratios in certain novae that develop dust are caused by condensation of grains from the gas, and can be used to determine the composition of the dust. In V1370 Aql, substantial silicate grain formation appears to have taken place, probably within the ionized gas.
Winds from Disks
Authors: Drew J.E.
Published: July 2016

The disks referred to in the title of this paper are specifically those present in cataclysmic variables in which the accreting white dwarf has a relatively weak magnetic field (≪ 1 MG). Such systems are classified either as nova-like variables or as dwarf novae, and are of interest here because they are believed to be novae in quiescence (Ritter and Livio discuss this point elsewhere in this volume).

This review aims to do two things: i) to summarise what has been learned about the winds associated with non-magnetic cataclysmic variables both from observation and from numerical modelling, and ii) to outline ideas about the nature of the mass loss mechanism. By contrast with the certainty that nova outflows are the consequence of thermonuclear runaway, it shall be seen that the fundamental cause of mass loss from cataclysmic variables remains obscure. An earlier review of this subject is by Cordova and Howarth (1986). Also of interest are some sections of the monograph on dwarf novae and nova-like variables by LaDous (1989).
Physics of Mass Ejection During Nova Outbursts
Authors: Kato Mariko
Published: July 2016

During nova outbursts a large part of the envelope mass is blown off. This mass ejection is caused mainly by the radiation driven wind and by the Roche lobe overflow. Theoretical studies on the acceleration mechanisms are briefly reviewed. Finally, I present theoretical light curves for U Sco based on the steady wind approach.
Ionization and temperature structure in nova shells
Authors: Beck H. , Gail H.-P. , Gass H. , Sedlmayr E.
Published: July 2016

It is well known from observations that some novae show infrared continuum excesses indicating dust heating by the strong ultraviolet radiation field. It seems, however, that dust formation in nova shells depends on some yet unknown intrinsic parameters since the characteristic infrared excesses are not observed in all objects. To study the conditions under which dust nucleation may occur in nova shells, as a first step we investigate the time dependend ionization and temperature structure.
Formation of the Balmer Line in the Optically Thick Nova Envelope
Authors: Takeda Yoichi
Published: July 2016

Non–LTE effect and formation of the Balmer line Hα in the optically thick nova wind expected from the radiation–pressure–driven continuous ejection model (cf. Bath and Shaviv, 1976; Ruggles and Bath, 1979) was investigated by use of the pure–hydrogen spherical model atmosphere, in which constant radial expansion velocity, inverse square law of density distribution, and planar grey temperature distribution were assumed. The coupled equations of radiative transfer and statistical equilibrium on the four levels plus continuum model atom (in which Hα line and Balmer–, Paschen–, and Brackett– continua are explicitly treated) were solved by the complete linearization procedure based on the comoving frame method (cf. Mihalas and Kunasz, 1978). We calculated four models as results of the combination of the surface density ρsurf (at ᵀRos = 10−13) (10−12 g/cm3, 10−13 g/cm3) and the expansion velocity Vexp (0 km/sec, 1000 km/sec). We assumed 1012 cm for the photospheric radius rph (at ᵀRos = 1), 10000 K for the effective temperature appearing in the temperature formula, and 100 km/sec for the microturbulent parameter. The low density models have larger extension (rsurf/rph ≃4.1) than the high density ones (rsurf/rph ≃1.7).
The Cyclic Evolution of Classical Novae
Authors: Prialnik Dina
Published: July 2016

The cyclic evolution of classical novae (CN) cannot be observed, as in the case of recurrent or dwarf novae. The duration of a typical cycle may range from a few thousand to a few 105 years. Thus we have to rely on theoretical studies for understanding the periodic outbursts — due to thermonuclear runaways (TNR) — on the surface of accreting white dwarfs (WD). One may distinguish between two kinds of studies: a) detailed investigations of a specific aspect or a particular evolutionary phase; b) studies which emphasize the cyclic behavior of novae and their long-term evolution. The latter, which form the subject of this brief review, may be divided into four groups, each adopting a different approach to the problem:

1.

Steady-state (semi-analytic) solutions;

2.

One- (or two-) zone models;

3.

Quasi-static (and/or steady burning) numerical calculations;

4.

Full-scale hydrodynamic evolutionary computations.
The Symbiotic Novae
Authors: Viotti R.
Published: July 2016

Symbiotic Novae are composite spectrum variables, whose light history is characterized by a single nova-like outburst. Their behaviour and time evolution is rather similar to that of classical novae, except for the much longer time scale, and the associated physics could be the same. We give an overview of the basic characteristics of the symbiotic novae, and their time behaviour in different frequencies. We find that the observed amplitude of outburst is mostly determined by the red star visual luminosity. The actual luminosity increase of the compact object might be much larger than that observed, and closer to that of classical novae. In some systems, the red star luminosity is possibly weakened by circumstellar dust. In symbiotic novae accretion should occur from the red star wind. Although the actual value of the accretion rate is still uncertain, thermonuclear runaway seems to better describe the symbiotic novae phenomenon. But new observational and theoretical work is needed.
A Spectroscopic Survey of Recurrent Novae at Minimum
Authors: Duerbeck H.W. , Seitter W.C.
Published: July 2016

From 1986 to 1988 optical spectroscopy near minimum of all then established recurrent novae (excluding recurrent X-ray novae such as V616 Mon and V404 Cyg) was carried out with the 3.6 m and 1.5 m telescopes of ESO, using EFOSC with CCD and the Cassegrain spectrograph with CCD or IDS, respectively. Flux-calibrated spectra of the six objects are shown in Figs, 1a – f. The most recent recurrent nova, V745 Sco, is included in the present discussion, because 1 month after outburst it had already reached a very late stage of outburst evolution. A spectrum of V745 Sco is shown in Schwarz et al. (1989).
High Resolution Spectroscopy of Symbiotic Stars
Authors: Schwarz Hugo E. , Duerbeck Hilmar W. , Seitter Waltraut C.
Published: July 2016

A high resolution spectroscopy survey of symbiotic stars is conducted in the southern hemisphere by the authors, using the Coudé Echelle Spectrograph (CES), equipped with a CCD at the ESO Coudé Auxiliary Telescope (CAT), and concurrently in the northern hemisphere by Bode, Evans, Meaburn and collaborators, using the UK facilities at La Palma. So far, more than 400 spectra of about 70 stars have been obtained, mostly during 1988 and 1989. The southern part of the work will be described below.

The discussion of symbiotic stars in the context of novae is not far-fetched. A number of symbiotics are known to have nova-like outbursts, and several novae are not easily distinguished from symbiotic stars. A noteworthy example is the most recently recognized recurrent nova, V745 Sco, first observed by Liller on July 24, 1989. It is described here, both because in late decline it represents a link between novae and symbiotic stars, and because of its current interest.
Spectral Line Formation in YY Ori and T Tau Envelopes
Authors: Bertout Claude
Published: July 2016

First results of line profile computations in a collapsing rotating envelope are discussed. As an application, an observed profile of the YY Ori star CoD -35° 10525 is compared to computed profiles. Possible similarities in the formation of YY Ori and T Tau line profiles are briefly mentioned.
Spectroscopic Observations of Old Novae
Authors: Bianchini A.
Published: July 2016

This communication gives some preliminary results of a spectroscopic survey of old novae presently carried out at Asiago Observatory. I have obtained image-tube spectra of 10 old novae in the spectral range 4000-7000 Å with dispersions from 60 to 180 Å/mm. The observed novae are: T Aur 1891, V 476 Cyg 1920, Q Cyg 1876, HR Del 1967, DN Gem 1912, DQ Her 1934, V 533 Her 1963, CP Lac 1936, V 841 Oph 1848 and GK Per 1901.
Disk Structure in U Geminorum
Authors: Madej J. , Paczyński B.
Published: July 2016

A hot spot at the outer rim of the accretion disk dominates the light of U Geminorum at minimum light. We take this as evidence that there is no accretion from the disk onto the white dwarf between the eruptions, and we assume there is no viscosity in the disk at that time. The hot spot is produced by dissipation of the radial component of velocity of stream falling from the inner Lagrangian point. Angular momentum per unit massis smaller in the stream than it is in the outer parts of the disk. This leads to angular momentum redistribution in the outer part of the disk. The difference of tangential velocity between the stream and the disk is dissipated in few orbital periods. These processes make the outer parts of the disk look like a torus. We calculated the structure of the torus in U Geminorum between the eruptions and we obtained the following oarameters: mass of the torus: 10-9 - 10-8 M⊙ (assumed), its optical thickness: 106, the large radius (i.e. the radius of the disk): 0.5 R⊙ (assumed), the small radius (i.e. the half thickness of the outer parts of the disk): 0.05 R⊙. Conditions at the surface of the torus are similar as on the solar surface.
Non Uniformity Expected in Nova Ejection
Authors: Friedjung M.
Published: July 2016

It is shown that according to the model of continued ejection of nova envelopes by radiation pressure, discrete clouds are probably formed. Their properties are discussed.
The Evolution of a Slow Nova Model with a Z = .03 Envelope from Pre-explosion to Extinction
Authors: Prialnik D. , Shara M.M. , Shaviv G.
Published: July 2016

A model for slow nova explosions is presented. The model consists of a 0.8 Mθ C/0 core and an envelope of 10−4 Mθ with solar composition. The envelope is assumed to have been accreted from a companion. The nuclear runaway produces luminosity close to the Eddington luminosity; this ejects 95% of the envelope. We find

I

CNO equilibrium burning on a timescale of 105.5 seconds produces enough energy for mass ejection.

II

The rise in luminosity stops close to the Eddington limit and the outer envelope layers accelerate via the continuous action of radiation pressure.

III

The mass outflow has two phases: a gentle outflow at the beginning and then a rapid outflow. In both phases we find ṁ ⋍ const., or equivalently, steady state outflow.

IV

The nova’s “shut-off” mechanism is the exhaustion of the envelope’s mass. In this “slow nova” model it took about 200 days for 95% of the envelope to be ejected and to leave behing a hot white dwarf.

V

The isotope ratios C12/C13, N14/N15 and O16/O17 are in good agreement with observations.

VI

The behaviour of LBOL(t) agrees well with observations. Several additional consequences are discussed.
Radio Molecular Line Observations of Late Type Stars
Authors: Winnberg A.
Published: July 2016

Radio observations of spectral lines from OH, H2O, SiO and CO have put the spot-light on late-type stars and revived the interest in them. Especially they have helped the understanding of the outer envelopes of these stars and of their mass loss. They also have revealed late-type stars that are hidden from observation at optical and near-infrared wavelengths by their dense surrounding shells of gas and dust. The strong maser lines from OH, H2O and SiO have additionally given us an excellent tool in mapping the distribution of late-type variables throughout the Galaxy. On the other hand, the interpretation of the maser amplified lines in terms of a model is difficult. Very-long-baseline interferometry (VLBI) of these lines might be a way of studying the geometry and kinematics of the envelopes but there are a few problems connected with these observations which I will point out in this paper. However, recently “thermal” microwave lines of SiO and CO have been observed from late-type stars. These lines might be easier to interpret regarding physical processes in the outer circumstellar envelopes. As so often when a new field is opening up in astronomy the solutions to several old problems have been found but at the same time many more new problems have been brought up.
Mass Loss and Cepheid Pulsation
Authors: Davis Cecil G.
Published: July 2016

This paper serves two purposes: 1) to discuss the latest improvements in nonlinear pulsation theory indicating the ability to resolve features such as the “Christy bump” on the light curves and 2) to show from the results of a bump model and recent observations that mass loss is one of the possible explanations for the mass discrepancy problem between evolutionary and pulsation theories. Recent observations by Sanford and Gow of Los Alamos and Bernat (McDonald Observatory) show that extensive mass loss has occurred in the evolution of the M supergiant α Orionis.
2. Initial Energy and Perihelion Distributions of Oort-Cloud Comets
Authors: Weissman P. R.
Published: July 2016

A Monte Carlo model of stellar perturbations of the Oort cloud is used to study the distributions in energy and perihelion of comets entering the planetary region for the first time. The model is run for a variety of initial states and a range of velocity perturbations. In all cases the resulting orbits are uniformly distributed in perihelion distance in the planetary region, q < 20 AU. Most orbits are confined to a fairly narrow range in 1/a and hyperbolic orbits are rare.
5. Jovian Perturbations Per Orbital Revolution for Short-Period Comets: Statistical Properties
Authors: Rickman H. , Vaghi S.
Published: July 2016

The gravitational perturbations by Jupiter per orbital revolution are calculated for six selected groups of 1000 hypothetical random comets of low inclinations, perihelia units 6 a.u. and aphelia in the range (4 a.u., 13 a.u.). The results are organized in the form of empirical distributions and their statistical properties are investigated in detail. They provide a rich material for the study of problems such as the orbital evolution of short-period comets and the origin of the Jupiter family.
6. The Satellites of the Major Planets: Were they All Captured?
Authors: Singer S. F.
Published: July 2016

Jupiter, Saturn, and Uranus have 15 (or possibly up to 18) regular satellites (i.e., with eccentricities and inclinations near zero) which are generally assumed to have been formed along with the planets and near their present orbits. We present evidence for their having been formed much later in the history of the solar system and in initial orbits very close to their respective planets. They then evolved to their present orbits, principally by tidal friction. Their source may be captured material, possibly of cometary origin.
2. Large Planetesimals in the Early Solar System
Authors: Hartmann W. K.
Published: July 2016

Inventories in sizes of large planetesimals can be estimated for different periods in the late planet-forming process by different techniques. For example, tabulations of craters on Mercury, the moon, and Mars give direct evidence of asteroid-like size distribution including bodies in excess of 100 km diameter. Large bodies exceeding, 1000 km diameter probably existed earlier. Consequences of interactions between planets and such bodies are considered.
7. Relationship Between Meteorites, Asteroids and Comets
Authors: Levin B. J.
Published: July 2016

There seem to be no objection any more to regard the asteroid belt as the past and present source of initial and intermediate parent-bodies of meteorites. Initial parent bodies were of the size of the present-day largest asteroids; the irregular size of medium sized asteroids suggests intermediate parent bodies fragmented by collisions. Finally, most of the terminal parent bodies can be identified with Earth-crossing or grazing objects. In contrast, icy planetesimals of the outer zone of the primeval nebula underwent almost no thermal evolution, but only a complicated orbital evolution leading to the comets observed now. This does not exclude the possibility that some extinct comets end up on asteroid-type orbits, although their nuclei might still contain ices covered by an insulating crust that can preserve them for a very long time. These could be the parent bodies of bolides, as opposed to meteorites.
6. Condensation and/or Metamorphism: Genesis of E- and L-Group Chondrites from Studies on Artificially Heated Primitive Congeners
Authors: Lipschutz M. E. , Ikramuddin M.
Published: July 2016

Primitive chondrites heated for one week under conditions reasonable for early solar system objects readily lose volatile/mobile trace elements, e.g., Ag, Bi, Cs, Ga, In, Se, Te, Tl and Zn. Trace element contents decrease by 10-100x progressively with temperature up to 1000° C; apparent activation energies calculated from these data suggest bonding differences between chondrites. Comparison of data for E3-6 chondrites and heated Abee (E4) indicates that volatile/mobile trace elements in E-group chondrites reflect metamorphic loss from a parent object; prior nebular cosmochemical fractionation modified non-volatile element contents. Apparently L3-6 chondrites escaped such open-system metamorphism. Information on nebular condensation process(es) may be gained from L-group compositional data; only nonvolatile elements in E-group chondrites should be used for this purpose, however.
7. A Comparison of Solar and Meteoritic Abundances
Authors: Holweger H.
Published: July 2016

Recent solar abundance data confirm the relationship between the sun and carbonaceous chondrites. New results for the solar S/Ca and Na/Ca ratio discriminate between types 1, 2, and 3. These and interstellar properties pose constraints on the condensation process. Protostellar separation of gas and grains will affect stellar metal content.
3. Pre-Main Sequence Heating of Planetoids
Authors: Sonett C. P. , Herbert F. L.
Published: July 2016

The problem of thermal metamorphosis of meteorites, possibly the Moon and Mercury, and perhaps other planetary objects is reviewed. Classical mechanisms of heating include fossil nuclides (especially 26Al), accretional heating, tidal heating, chemical reaction heat, and electrical induction. These various mechanisms involve constraints on the early thermal profiles of the Moon or Mercury. In the case of the meteorites, the primary contenders for a viable mechanism currently are fossil nuclides and electromaqnetic induction, or some combination of these. But the issue of energetic mechanisms in the early solar system remains enigmatic. The fossil nuclide hypothesis leads to constraints upon nucleosynthesis while electromagnetic induction places significant constraints upon electrodynamic effects such as solar spin damping.
7. The Solar Nebula Pressure Gradient and its Effect on Planetesimal Motions
Authors: Weidenschilling S. J.
Published: July 2016

In a centrally condensed solar nebula, the gas is partially supported by a pressure gradient, and rotates at less than the Keplerian velocity. Solid bodies lack this support, and spiral inward due to drag. The radial velocities developed can be significant, even in low-mass nebular models. Possible effects include fractionation of particles by size or density, rapid accumulation of planetesimals, and production of regions of anomalous (non-solar) composition in the nebula.