bluuebunny/crossref_metadata_2025 huggingface dataset:
The Scattering Matrix of Randomly Oriented Infinite Cylinders
Authors: Stammes P.
Published: July 2016

A method is outlined to compute the scattering matrix of an ensemble of infinite cylinders in random orientation, as an approximation to the scattering matrix of an ensemble of very long but finite cylinders. Numerical checks are presented, which show that the results for infinite cylinders agree with theoretical results for very thick and very thin cylinders, as well as with numerical data for prolate spheroids and short finite cylinders.
The Micrometeoroid in the Upper Atmosphere
Authors: Kamijo F.
Published: July 2016

The temperature and the radius variation of micrometeoroids in the thermosphere and the mesosphere are calculated theoretically. If the radius and the initial velocity are 100μm and 30 km/sec respectively, the evaporation height and the velocity coincide almost exactly with those of the Capricornids and the Virginids from the meteor stream observation.

Moreover, it is shown that the not evaporated debris till the end of the sublimation may become spherules in the bottom of deep sea; and that fluffy micrometeoroids (10μsize) floating in the stratosphere are also consistent with our calculation.

The recondensation and the coagulation of the evaporated gas molecules from the meteoroid are also calculated, and it is shown that these secondary particles are very small and few.
The Annual Variation of Radio Meteor Echoes Observed from 1981 to 1985
Authors: Suzuki Kazuhiro
Published: July 2016

The radio observations of meteor echoes using FM broadcasting were carried out from January, 1981 to June, 1985. The annual variation of meteor rates in the 5 years was obtained from the observations made from 25h through 29h in local time (16h-20h UT).

Some features in this annual variation can be explained by the occurrence of the major meteor showers. After the effects of these major showers are removed there remains a significant annual variation which shows higher rates in the winter half of the year (October to March). This seems to be caused by the annual variation of non-shower meteors radiating from the apex region.
The Taurid Complex: Giant Comet Origin?
Authors: Steel D.I. , Asher D.J. , Clube S.V.M.
Published: July 2016

The formation and evolution of the Taurid Complex of interplanetary objects is modelled on the basis of the parent being a giant comet which entered the inner solar system some time in the past 10,000-20,000 years. The orbital element distributions for the presently-observed meteor showers are discussed in terms of how these can constrain any model for the origin of the overall complex. As a baseline model we present results from the numerical integrations of fictitious meteoroids released from a comet over ten millenia, this comet having initial elements similar to those derived from a backwards integration of P/Encke. Large relative velocities at perihelion, above those feasible in conventional ejection scenarios, are necessary; we ascribe these to jetting of organics and other volatiles soon after release. Such a model gives a good first-order fit to the observed orbits, although additional processes (cometary splitting or asteroidal collisions) appear also to be necessary to explain the Taurids.
Catastrophic Disruption of Solid Bodies by Collision — Experimental Approach —
Authors: Fujiwara A.
Published: July 2016

The results on mass, velocity, shape, and rotation of the fragments produced in the disruption experiments by impact are surveyed. Some future works are also suggested.
Characteristics of Interstellar and Circumstellar Dust
Authors: Tielens A.G.G.M.
Published: July 2016

This paper reviews our current knowledge of interstellar and circumstellar dust from an observational point of view. It is concluded that interstellar dust is highly heterogenous. It consist of a large number of different materials formed in a great variety of stellar birthsites under varying conditions and each with a highly isotopically anomalous composition in its main elements.
Chemical Composition of Dust Expected from Condensation Models
Authors: Yamamoto Tetsuo
Published: July 2016

This review examines to what degrees the present chemical equilibrium condensation models are effective in predicting chemical composition of grains observed in a variety of cosmic environments. The composition expected from the equilibrium calculations is reviewed separately for refractory (rocky and metallic) and volatile (icy) components. Comments are given on the limitation of the equilibrium calculations in predicting the grain composition. By taking cometary ice as a typical cosmic volatile condensate, it is pointed out that its composition is far from that expected from the equilibrium models. Theories on the formation of cometary volatiles are reviewed, and an observational clue helpful to testing the theories is pointed out. Discussion is given on the advantage for formation of organic materials from volatile solids.
The Source Composition of Galactic Cosmic Rays as Possibly Originated from the Dust in the Circumstellar and Interstellar Space
Authors: Sakurai Kunitomo
Published: July 2016

The chemical composition of galactic cosmic rays in their sources is similar to that of interstellar clouds or grains which are relatively enriched in refractory and siderophile elements as compared with the chemical composition of the solar atmosphere. Taking into account this fact, it is shown that the cosmic ray source matter can be identified as the dust or grains observed in the envelopes of red supergiant stars or the matter originally ejected from supernova explosions.
Radial Motions Near the Galactic Centre and the Origin of Galactic Spiral Structure
Authors: Schmidt-Kaler Th.
Published: July 2016

The fundamental difficulty of explaining the spiral structure of galaxies by material arms is the winding dilemma which restricts the life-time of a spiral to about one rotation period. This dilemma is resolved by the density wave concept. However, the density waves are damped by various processes. We calculated the life time of the density wave for our Galaxy (τ = 8.108yrs) as well as for 24 nearby spiral galaxies with well-known data. It appears that the density wave can explain the existence of spiral arms for only about three rotation periods. After that time the energy of the wave has to be re-supplied. For this, various mechanisms have been proposed, e.g.

1) tidal origin – which requires rather special circumstances

2) resonant interaction – which is energetically insufficient

3) local Jeans-type instability in the outer regions – which also may not be able to provide sufficient energy

4) explosions of the nucleus – which involve high inclinations to the plane.
Abundances and Ages of Disk Clusters
Authors: McClure Robert D. , Twarog Bruce A.
Published: July 2016

Larson has emphasized at this meeting that one relation which is valuable in determining the correct model for the formation of the Galactic disk is the dependence of stellar abundances on the time of formation of the disk stars. While Mayor has demonstrated that correlations exist between metal abundance and both kinematics and positions of stars in the disk, Larson has suggested that it is possible in an extreme infall model to have such trends and still have no age dependence.
What Happened to Stellar Drifts?
Authors: Clube S.V.M.
Published: July 2016

The concepts of a local standard of rest and a standard solar motion and the nature of the data giving rise to these concepts are so much part of the given knowledge of galactic astronomy that it hardly seems possible that anything new might be learnt from continued study of this subject. But the examination of local stellar kinematics is by no means a tidy subject, and the history of its development does conceal one or two peculiarities which bear reconsideration.
Vertical Force Law Kz and Chemical Gradient in the Galaxy
Authors: Martinet L. , Grenon M.
Published: July 2016

At Tbilissi, Prof. Blaauw (1975) reported on results of uvby photometry of F-type stars and showed a relation between the quantity Δm and the distance z to the galactic plane. This relationship could be interesting if Δm1is a non ambiguous indicator of metallicity. It was found that the mean relative metal abundance decreases by a factor of about one third between 0 and 700 pc. The same type of relationship was obtained by M. Grenon (1976) for K giants and shows a lower variation of the metallicity with z.
Halo Mass in Spiral Galaxies
Authors: Terzides Ch. K.
Published: July 2016

We have solved the dispersion relation given by the theory of Lynden Bell and Kalnajs (1972) using models with spherical halos under the assumption that the halo population does not participate in the spiral arms. Especially we have studied the conditions under which the solutions of this dispersion relation reach corotation so that the excitation mechanism of the density waves due to the theory of Lynden Bell-Kalnajs is applicable. We have used as basic axisymmetric models the model of Schmidt (1965) (S-model) and the model proposed by Miyamoto and Nagai (1975) (M-model) On these models we have superimposed spherical halos so that in a sphere of radius 20 kpc there exists a given amount of mass with two different density laws: ρ as r-1and p as r-2.
The Effect of Crossing Times Through the Solar Neighbourhood on the Observed Stellar Age and Metallicity Distributions
Authors: Turon Lacarrieu C. , Mayor M. , Martinet L.
Published: July 2016

The effect of crossing times through the solar neighbourhood on the observed stellar age and metallicity distributions due to the oscillations perpendicular to the galactic plane is well known. Stars with high z-velocity are under-represented since they stay much longer far from the galactic plane than near the sun. Since the age and metallicity distributions of these high velocity stars are quite different from the age and metallicity distributions of all the stars moving at a mean distance10 kpc from the galactic centre, a weighting procedure has to be adopted. The weight to be assigned to each star should be proportional to the ratio of the oscillation period in z, i.e. Tz, to the time spent within a sphere centered on the sun, i.e. τz. An approximate formula has been given by Woolley (1970):. The effect of such a weighting procedure is very important : the ratio Tz/Tzvaries from 1 to more than A between young and old stellar populations. It has to be noted that the quadratic term of weighting (often neglected) is equal to the linear term for a |w| velocity of about 55 km/s.
The Standard Solar Model
Authors: Bahcall J.N. , Cribier M.
Published: July 2016

The main features of standard solar models, the logic of the calculations, and some of the important results concerning solar neutrinos experiments are given. The input parameters that cause the greatest uncertainties in the calculated neutrino fluxes are the nuclear rection rates, the chemical abundances, the radiative opacity, and the equation of state. This article is based, with permission of the publisher, on Chapters 1 and 4 of Neutrino Astrophysics by J. N. Bahcall, Cambridge University Press (1989).
Astrophysical Opacities at LLNL
Authors: Iglesias Carlos A. , Rogers Forrest J.
Published: July 2016

In an effort to reduce uncertainties in the theoretical radiative opacities a new code has been developed at LLNL which removes several of the approximation present in past calculations. Results from the new code with comparisons to other available opacity calculations are presented as well as experiments.
Comments on Solar Convection
Authors: Deubner Franz-Ludwig
Published: July 2016

This contribution discusses observational aspects of the evolution of individual structures of solar convection.

It has been shown, that mesogranulation is a convective phenomenon that fits well into the gap between granulation and supergranulation. Apparently this observation justifies the view that the three members of the granulation family represent sections of a broad continuum of convective motions spanning the range of sizes from a yet unknown fraction of 1 Mm to about 50 Mm. Nevertheless, power spectra of velocity and brightness fluctuations exhibit three maxima, separated by intervals with significantly less power near 3 Mm and 7.5 Mm. Do these gaps give reasons for reconsidering the old idea, that each of the three characteristic scales has its own source layer at a certain depth in the convection zone?

Power spectra of the granular energy distribution near the observational limit of spatial resolution suggest a continuous transfer of kinetic energy to smaller eddies by turbulent decay of the larger scale elements. Morphological studies of granular evolution and a comparison of the observed spectral line bisectors with theoretical predictions seem to disprove this idea. These observations imply either that the turbulent cascade, if it exists, is buried in the spatially unresolved part of the power distribution, or that radiative losses ultimately limit the life time of individual granules on all scales.
A Review of Observational Helioseismology
Authors: Duvall Thomas L.
Published: July 2016

There have been several excellent reviews of observational helioseismology in recent years. These include the reviews by Harvey (1988), Libbrecht (1988), and van der Raay (1988) presented at a recent conference in Tenerife. The present effort will concentrate on the progress made on solar rotation recently.

The Sun is a resonant cavity that supports many (~ 107) modes of oscillation. The modes that are most easily observed are the acoustic or p-modes. The eigenfunctions for these modes are:

fnl(r) is the radial part of the separable eigenfunction where r is the radial coordinate measured from the center of the star. n is the number of radial nodes in the eigenfunction. Ylm (θ,ϕ) is the spherical harmonic function, where θ is the colatitude and ϕ is the longitude. The spherical harmonic degree l is the number of nodes of the spherical harmonic measured along a great circle that makes an angle with the equator. The azimuthal order m is the number of nodes around the equator. The frequency of the eigenmode, vnlm, depends on the mode. Much of our information derived about the solar interior from helioseismology comes from the measurement of these frequencies.
Magnetic Field in the Sun’s Interior from Oscillation Data
Authors: Dziembowski W.A. , Goode P.R.
Published: July 2016

Solar oscillations provide a probe of the internal magnetic field of the Sun if the field has sufficient intensity. Using the oscillation data of Libbrecht, we find evidence for a 2 ± 1 megagauss quadrupole toroidal field centered at 0.7 of the solar radius which is barely beneath the base of the convection zone. This field, by its location and symmetry, may be associated with the dynamo that drives the Sun’s 22-year activity cycle.
Optical Studies of Classical Novae in Outburst
Authors: Seitter Waltraut C.
Published: July 2016

A nova is followed optically from preoutburst to postoutburst appearance. Photospheric and atmospheric observational data are explained qualitatively through the energy budget, apparent in super-Eddington, Eddington, and sub-Eddington states, and the particle fluxes, according to their role in Grotrian’s model. In some instances, interpretations connected with Grotrian’s model are compared to results based on hydrostatic atmosphere models, for which quantitative versions exist. It is hoped that the physically and observationally sound ‘Ansatz’ of Grotrian may find followers to formulate an updated and extended theory.
New Results About Post Optical Maximum Oscillations of Novae
Authors: Bianchini A. , Friedjung M. , Brinkmann W.
Published: July 2016

New results presented include the oscillations of intervals between maxima of light oscillations, while in the case of GK Per the Orion system velocities oscillated with twice the light oscillation period.
Nova Ophiuchi 1988: 0.9–1.35 μm Spectroscopy
Authors: Lynch David K. , Rudy Richard J. , Rossano George S. , Erwin Peter , Puetter R. C.
Published: July 2016

Near IR grating spectrophotometric observations (λ / Δλ ≃ 400 ) of Nova Ophiuchi 1988 between 0.9 and 1.35 μm on September 22.2, 1988 UT (J.D. = 2447426.7) are reported. We observed the nova with the Lick Observatory 3–meter Shane telescope using the Aerospace cooled grating spectrometer. A 7.5 arc sec aperture was used. The detector was a germanium photodiode, cooled to 77 K and used in conjunction with a charge integrating amplifier. These are the first IR observations ever made of a slow nova.

Figure 1 shows the spectrum which contains Paschen emission lines β, γ δ, ε, ζ, η, He I λ1.083 μm, and a very weak continuum, all consistent with a post-maximum, early nebular phase. Figure 1 also shows a number of possible weak lines including [ Fe II ] and He I as well as an unidentified feature at 1.01 μm in the far red wing of Paδ. The line to continuum ratio for He I λ1.083 is about 300. The emission lines are resolved in the stronger features ( Paδ Paζ, Paβ, and He I λ1.083) and show a mean FWHM of 900 ± 150 km/sec.
HeI emission line formation in symbiotic stars and novae
Authors: Schmid H.M.
Published: July 2016

The HeI triplet to singlet line ratio Λ = F(λ5876)/F(λ6678) in symbiotic stars and novae is often much lower than the planetary nebulae value of ≈ 3.5, which is also the low density value Λ0 predicted by recombination theory.

Fig.1 shows that the dereddened HeI line ratios ^ are different for S type and D type symbiotic stars. The spectrophotometric data are mainly from Allen (1984, personal communication) and Blair et al.(1983). The S and D type classification divides the symbiotic stars according to the IR continuum into objects with a stellar continuum or dust emission. Practically all D types have low nebular densities Ne ≲ 107cm−3 and a rich spectrum of forbidden lines, while in S type objects these lines are suppressed by collisional deexcitation due to the high electron densities Ne ≳ 107cm−3. The observed HeI line ratio ^ in S type symbiotics, which is systematically too low when compared with the theoretical low density value Λ0 = 3.5, can therefore be attributed to the high nebular densities in these objects.
Classical Novae in the Context of the Evolution of Cataclysmic Binaries
Authors: Ritter Hans
Published: July 2016

In this paper we explore to what extent the TNR model of nova outbursts and our current concepts of the formation and secular evolution of cataclysmic binaries are compatible. Specifically we address the following questions: 1) whether observational selection can explain the high white dwarf masses attributed to novae, 2) whether novae on white dwarfs in the mass range 0.6M⊙ ≲ M ≲ 0.9M⊙ can occur and how much they could contribute to the observed nova frequency, and 3) whether the high mass transfer rates imposed on the white dwarf in systems above the period gap can be accommodated by the TNR model of nova outbursts.
The Theoretical Frequency of Classical Nova Outbursts as a Function of White Dwarf Mass
Authors: Politano Michael , Livio Mario , Truran James W. , Webbink Ronald F.
Published: July 2016

Using the distribution of white dwarf masses in zero-age cataclysmic variables (CVs) calculated by Politano and Webbink (these proceedings), the relative frequency of classical nova outbursts as a function of white dwarf mass is calculated. These results are compared with the results obtained by Truran and Livio (1986), who calculated the same function, but used a distribution of white dwarf masses in CVs calculated from a Salpeter initial mass function and a particular progenitor mass-white dwarf mass relationship for single stars.

We wish to calculate the frequency of classical nova outbursts as a function of white dwarf mass. To do this, we require two quantities: 1) the recurrence frequency of classical nova outbursts (i.e., how many outbursts per year) and 2) the white dwarf mass spectrum in classical novae (i.e., number of novae per white dwarf mass). We discuss each of these in turn.
On the Nature of the Outflow from Nova Stars Occurring Immediately After Ejection of an Envelope
Authors: Gorbatsky V.G.
Published: July 2016

According to modern conceptions the cause of nova outbursts is a thermal runaway (TR) taking place in the deep layers of the accreted envelope of a white dwarf (WD), component of a close binary system. The theory of TR was considered by many authors and, especially, has been developed in detail by Starrfield et al. (1974, 1984). It has been shown that when the pressure at some level in the envelope reaches a critical value Pcr, the thermonuclear reactions of the “hot” CNO cycle become very fast, and after a time interval of several tenths seconds the temperature at this level rises to (2 ÷ 3)× 108 K. If the CNO abundances are high enough, the total outburst energy may exceed 1047 ergs. As a consequence of TR, a considerable fraction of the envelope mass (20% ÷ 50%) must be torn off by shock waves. As suggested by Starrfield et al. (1974), the remaining matter forms an extended atmosphere (R ≃ 1011 cm) and the star transforms itself into a supergiant having a luminosity L* ≲ Ledd during several months.
Recurrent Novae
Authors: Webbink Ronald F.
Published: July 2016

Thermonuclear models of recurrent novae demand white dwarf accretors near the Chandrasekhar mass. In this case, the known recurrent novae should possess classical counterparts bearing the same structural parameters and space distribution, save for having only marginally less massive white dwarfs. Furthermore, recurrent novae should occur exclusively on ONeMg white dwarfs, and display in their ejecta either neon-group overabundances (if the white dwarfs are eroded through an outburst cycle) or no heavy element enhancements whatever (if the white dwarfs increase in mass).

The known recurrent novae are reviewed in the light of these and other characteristics of thermonuclear runaway models, and also in terms of accretion-powered events, with special attention to the difficulties encountered by both models. Pivotal tests to distinguish between between thermonuclear and accretion models rely on the fact that the latter require far more mass transferred than the former to produce the same outburst energetics. Thus, photospheric opacities in thermonuclear recurrent novae are dominated by scattering; those in recurrent accretion events by true absorption. Orbital period changes through outburst are 103 times greater in accretion models than in thermonuclear models.
Possible X-Ray Flares in a Recurrent Nova
Authors: Hachisu Izumi , Itoh Hiroshi
Published: July 2016

The dynamical evolution and nonequilibrium X-ray emission of recurrent nova remnants have been investigated by using a spherically symmetric hydrodynamic code. We assume that the nova ejecta expand into a wind from a red-giant companion. The wind material is blast-shocked, and emits copious X-rays. The blast shock soon breaks out of the wind region and the X-ray emission declines drastically. The blast shock eventually catches up with the relatively slow ejecta of the previous outbursts. The X-ray emission may then be rejuvenated in both luminosity and spectral shape.
Co-ordinated Optical and Radio Observations of Symbiotic Stars
Authors: Ivison R. J. , Bode M. F. , Meaburn J. , Davis R. J. , Nelson R. F. , Spencer R. E.
Published: July 2016

We present preliminary results from absolutely flux-calibrated optical spectroscopy, together with 5 GHz radio flux measures of 17 symbiotic stars. The data were obtained quasi-simultaneously using the Manchester Echelle Spectrograph on the Isaac Newton Telescope, La Palma between 1988 September 20 and 24, and the Broad Band Interferometer at Jodrell Bank during 1988 October. This represents the largest sample of these stars observed in this way to date. Distances are calculated using visual extinctions and are compared with other quoted values. In general, the agreement is surprisingly good. Plots of individual line luminosities vs. radio luminosity indicate that the D-type (dusty) symbiotics (both also proto-planetary nebulae) have far higher radio luminosities than S-types (stellar) for comparable recombination and forbidden line luminosities. This may however be due to underestimation of optical line luminosities for the D-types as the circumstellar extinction contribution is uncertain. The single D’-type (cool dust, yellow secondary) lies at the low luminosity end of the S-type region. ‘Very slow novae’ in our sample lie in both groups.
Red and Near Infrared Spectra* of Pre-Main Sequence Stars I. A Preliminary Investigation of T Tauri Stars
Authors: Andrillat Y.
Published: July 2016

230 Å mm-1 spectra of 30 stars of T Tauri or related type were obtained in the 8000-11000 Å region using a grating spectrograph equipped with an S-1 photocathode image-tube. In addition a few T Tauri stars were observed at the same dispersion in the 6200-8800 Å region on IN plate. A preliminary qualitative analysis of the observations leads to possible correlations between the intensities of emissions of the Ca II triplet, Paschen series and He I 10830 Å, and the spectral type, K-L color index of the star, or the [0 I] and Fe II intensities in the visible spectrum.
Flare Star Observations in the Praesepe Region
Authors: Jankovics I.
Published: July 2016

In a program of systematic search for flare stars in clusters and associations we have carried out a photographic survey in the region of Praesepe. The previously obtained interesting results in the Pleiades cluster and the Orion association stimulated us to continue the work of Haro (1968) and Rosino (1966) in Praesepe. The importance of observations in this cluster is obvious if we consider the following circumstances:

1. Praesepe and Pleiades have nearly the same distance from the Sun, 160 and 125 pc, respectively.

2. There exists a difference in age between the 2 clusters of at least one order of magnitude.

3. The use of Schmidt telescopes allows observations in large cluster regions.

A great number of observational data are desirable for comparison of flare activity in the regions of Pleiades and Praesepe.
The Unusual Object KR Aurigae
Authors: Popova M.D. , Vitrichenko E.A.
Published: July 2016

The photometric and spectrographic data of the peculiar variable KR Aur have been analyzed. The Hβ line contour shows an accretion with velocity of 3200 km/s. The assumption is made that KR Aur may be a black hole.
Nova V1500 Cyg - Photometry and Period Variations Study
Authors: Semeniuk I. , Kruszewski A. , Schwarzenberg-Czerny A. , Chlebowski T.
Published: July 2016

This study aims to present our photometric observations of Nova Cygni V1500 1975, and to discuss the period changes of brightness variation on the basis of all available data.

The Nova was observed from 2 September 1975 to 26 October 1976 using the single channel UBV photometer attached to the 60-cm reflector of the Ostrowik station of Warsaw University Observatory. The brightness of the Nova decreased considerably during that time and it was necessary to use a sequence of four comparison stars. The variable was usually monitored in the V filter and occasionally measured with B and U filters. The V band is not well suited for observing novae in the nebular stage, since the dominant light contribution comes from O III emission lines.
Nova Models and their Problems
Authors: Thomas H.-C.
Published: July 2016

Very detailed spectroscopic and photometric observations of Novae are available today. Unfortunately they do not directly tell us what suddenly makes a star a million times brighter, sometimes even transforming the familiar constellations on the sky. Twenty-five years after its publication, Mestel’s (1952) metaphor of a gigantic hydrogen bomb seems to be most widely accepted, although he at that time applied his model to a Supernova outburst. Later Giannone and Weigert (1967) as well as Rose (1968), Saslaw (1968) and others have computed hydrostatic models of such an event, using Kraft’s (1963) binary model of a late type main sequence star and a white dwarf. Detailed hydrodynamic computations were carried out by Starrfield and his collaborators (for references see Sparks, Starrfield, and Truran, 1977) and recently by Prialnik, Shara, and Shaviv (A & A 62, 339, 1978).
The Interaction of Accretion Flux with Stellar Pulsation
Authors: Papaloizou J.C. , Pringle J.E.
Published: July 2016

We consider the usual hypothesis that the short period coherent oscillations seen in cataclysmic variables are attributable to g-modes in a slowly rotating star, for details see Papaloizou and Pringle (1977). We show that this hypothesis is untenable for three main reasons: (i) the observed periods are too short for reasonable white dwarf models, (ii) the observed variability of the oscillations is too rapid and (iii) the expected rotation of the white dwarf, due to accretion, invalidates the slow rotation assumption on which standard g-mode theory is based. We investigate the low frequency spectrum of a rotating pulsating star, taking the effects of rotation fully into account. In this case there are two sets of low frequency modes, the g-modes, and modes similar to Rossby waves in the Earth’s atmosphere and oceans, which we designate r-modes. Typical periods for such modes are 1/m times the rotation period of the white dwarfs outer layers (m is the azimuthal wave number). We conclude that non-radial oscillations of white dwarfs can account for the properties of the oscillations seen in dwarf novae.
Secular Mass Loss from Cataclysmic Variables
Authors: Smak Józef
Published: July 2016

The mass loss from cataclysmic binaries seems an important and worth studying phenomenon for a number of reasons. It is probably enough to mention only two of them:

(a) Whenever we can directly observe the ejected material, determine its amount and the rate of mass loss, as well as its chemical composition (this being the case of the expanding envelopes of novae), we are getting a good insight into the basic physical mechanisms responsible for the observed phenomena.

(b) The mass loss (together with the mass transfer) and the loss of the orbital angular momentum are related directly to the dynamical evolution of a binary system and - indirectly - to the evolution of its components.
Period Changes of W Ursae Majoris Stars
Authors: Kreiner J.M.
Published: July 2016

About 6000 times of minima for 120 W Ursae Majoris stars were collected by Mrs. Z. Frasińska and the writer in the Cracow Astronomical Observatory. From this material 15 O - C diagrams (fig. 1) with large number of minima were taken into consideration. Each of them covered more than 30,000 epochs. The analysis of O - C curves leads to the following conclusions:

1. The periods of all well-observed W UMa stars are variable.

2. There are no “pure” parabolae in well-observed O - C curves.

3. The periods change in a rather short time and then remain constant for 5,000 - 25,000 E (fig. 2).

4. The number of increases and decreases of periods is approximately the same. The mean absolute change of period of 15 investigated stars amounts to 0.d00000365 = 0.P0000105. (The mean increase of period = 0.d00000386 = 0.P0000109, the mean decrease of period = 0.d00000349 = 0.P0000102).

5. The mean absolute change of period for 15 investigated stars was plotted versus parameter q (mass ratio = m2/m1) (fig. 3). Systems with almost equal masses of stars have a tendency to show violent changes of period.
Infrared Observations of Late Type Stars
Authors: Merrill K.M.
Published: July 2016

Substantative mass-loss resulting in appreciable circumstellar dust envelopes is common in late-type stars. The evolutionary history and physical state of a cool star determine the chemistry within the outer stellar atmosphere mirrored by the molecular and particulate material present in the envelope. The observational consequences of this debri determined by moderate spectral resolution (λ/Δλ ~ 50-100) infrared spectrophotometry are reviewed. Significant information is provided by observations of the emergent energy flux of both the cool stellar photosphere and of the circumstellar dust envelope. While most of the infrared features observed in late-type stars can be plausibly identified, an as yet unknown emission mechanism marked by strong infrared band structure is known to be operative in a variety of infrared sources. The observed range in shell optical depth in both M and C stars suggests that mass-loss occurs to some degree throughout late stellar evolutionary phases and that occasional periods of high mass-loss are not uncommon.
Optical Information on Mass-Loss from Evolved Stars
Authors: Reimers D.
Published: July 2016

Mass-loss from red-giant stars has been proved by optical observations of violet displaced absorption cores in strong metal lines of low excitation (Deutsch, 1956) long before vast circumstellar shells around the most luminous stars were detected by infrared radiation from circumstellar dust (Gillet et al. 1968, Woolf and Ney, 1969), by intrinsic polarization of star light (e.g., Serkowski, 1966) and by molecular microwave emission (Wilson and Barrett, 1972). Hot expanding coronae which emit UV lines of highly ionized metals were detected only recently in G and K giants (e.g., β Gem, Gerola et al., 1974).
Theoretical Aspects of Mass Loss from Late-Type Stars
Authors: Weymann Ray J.
Published: July 2016

Since Deutsch’s (1956) discovery that in α Herculis the displaced circumstellar absorption lines common in the spectra of late-type giants and supergiants really represented a loss of matter, the evidence that this is a very extensive and common feature among all late giants and supergiants has become very persuasive. To the extensive optical spectroscopic evidence for mass loss from these stars originally obtained by Deutsch and subsequently by others, we may now add observations of infrared excess from dust in circumstellar envelopes (Merrill 1977), radio molecular line radiation from expanding shells (Winnburg 1971), thermal and possibly 21 cm radio radiation from ionized and neutral hydrogen respectively (Smolinski et al. 1977; Zuckerman 1977) and the direct photographs of the envelope of α Ori in the light of one of the potassium resonance lines from scattered stellar radiation (Bernat et al. 1977).
On Mass Loss from Long Period Variables
Authors: Gorbatsky V.G. , Fedorova O.V.
Published: July 2016

Observations show that long period variables (LPVs) as well as many other giant and supergiant stars are losing mass extensively. As evidence of mass loss one can mention the presence of circumstellar envelopes around LPVs. Such envelopes are inferred from infrared excesses (Gehrz and Woolf, 1971; Reimers, 1975) and maser radiation. P Cyg type profiles are observed in the spectra of some LPVs (Sanner, 1977). The increased brightness of the companion of Mira (a white dwarf) has been interpreted as the result of accretion of matter ejected by the primary (Shklovsky, 1976).
Mass Ejection from Old Stars - An Example of a Possible Mechanism
Authors: FitzGerald M.P. , Kwok S. , Pruton C. R.
Published: July 2016

The basic ideas in this paper are described in recently published papers by Ahern et al. (1977) and Kwok (1977). There are two main points to be made in addition, which remove the differences between these two papers.
Mass Loss from Stars and the Chemical Evolution of the Interstellar Medium
Authors: Biermann P.
Published: July 2016

Mass loss from stars returns processed as well as unprocessed material to the Interstellar medium, and thus enriches it in helium and heavy elements. In this very brief review we outline the theory of the chemical evolution of the interstellar medium.
7. Meteor Streams in the Making
Authors: Sekanina Z.
Published: July 2016

The well-known associations of meteor streams with periodic comets and the probable cometary origin of the zodiacal dust cloud point to the importance, in the cometarg debris, of particles with masses exceeding roughly 10-6 gram. It is shown that these large particles dominate in the sunward-oriented anomalous tails of comets. Their study is essential for meaningful estimates of the mass of meteor streams and of the injection rate of the cometary debris that contributes to the zodiacal cloud. Favorable conditions for the detection of anomalous tails can be recognized in advance, as demonstrated by the successful predictions for comets Kohoutek (1973 XII) and Bradfield (1975p). To answer the question as to whether short-period comets can support the zodiacal cloud, a study of anomalous tails at future returns of these comets is considered indispensable.
5. Asteroid Infrared Reflectances and Compositional Implications
Authors: Matson D. L. , Johnson T. V. , Veeder G. J.
Published: July 2016

This paper assesses the state of asteroid infrared reflectance measurements and discusses what they have contributed to our understanding of asteroidal surfaces. The data suggest that space weathering has not significantly affected the optical properties of the asteroids. Thus comparisons of asteroid reflectance spectra with unweathered meteorite and rock data is a valid procedure. The high 1.6 and 2.2 μm reflectances of a number of asteroids strongly suggest the presence of a metallic phase.
5. Populations of Planet-Crossing Asteroids and the Relation of Apollo Objects to Main-Belt Asteroids and Comets
Authors: Shoemaker E. M. , Helin E. F.
Published: July 2016

From discoveries made in several independent surveys of the sky, the number of Apollo asteroids to absolute visual magnitude 18 is estimated to be of the order of 103; the ratio of Mars-crossing asteroids to Apcllos is estimated to lie between 10 and 60. The loss of Apollos to magnitude 18 over the last 3 billion years, by collision with the planets and ejection from the solar system, is estimated to have been several times 104 objects. Mars-crossing asteroids appear to be an inadequate source for all of these objects. Most Apollos probably are dead short-period comets.
9. Unusual Primitive Meteorites: Chondritic Inclusions from Group IAB Iron Meteorites
Authors: Bild R. W.
Published: July 2016

Several meteorite types, distinct from the large chondrite groups (H, L, LL, E and carbonaceous), are known to also have chondritic compositions. These meteorites preserve information on conditions at additional formation locations in the early solar nebula. Silicate inclusions from group IAB iron meteorites are one such type. Evidence for their chondritic nature is given and their formation discussed.
5. The Chemical Relationship between Howardites and the Silicate Fraction of Mesosiderites
Authors: Simpson A. B. , Ahrens L. H.
Published: July 2016

Analyses of eleven major elements in five howardite samples and in the silicate fraction of seven mesosiderites are presented in a recalculated form and compared. The mesosiderite silicate fractions show distinct differences in chemical composition from the howardites, but the average Ca/Al determined for mesosiderites (1.05), which differs from most values previously published, is close to that typical of howardites (1.08). The inverse Ca/Mg relationship in the howardites is present also in the mesosiderites, the trend being displaced relative to that of the howardites but parallel to it. The chemical differences confirm that mesosiderites are not mixtures of howardite and metal. The Ca/Al and Ca/Mg relationships suggest that the two meteorite groups were subject to similar genetic controls, and may therefore have had a common parent body. Such a body is required by the cooling rate of the metal of mesosiderites to have been larger than any known asteroid.
4. Oort’s Cometary Cloud in the Light of Modern Cosmogony
Authors: Safronov V. S.
Published: July 2016

Although the existence of Oort’s cometary cloud has been generally accepted, his hypothesis on its origin has been repeatedly called into question, in particular because of the large mass that Jupiter would also have simultaneously ejected out of the solar system. However, the extremely slow growth of particles in regions of small density seems to rule out that comets condensed “in situ” at their present large distances. Also, the accumulation of interstellar grains in satellite disks orbiting around the primitive solar nebula seems an “ad hoc” hypothesis that cannot be proved or disproved. Therefore, the most reasonable hypothesis is that comets were ejected from the region of the giant planets as a natural by-product of their accretion.
5. Low-Temperature Condensates in Comets
Authors: Delsemme A. H. , Rud D.
Published: July 2016

Recent observational data on the volatile fraction of comets are confronted with a model based on the fractional condensation, in the 80-100 °K range, of a higher-temperature equilibrium obtained from a solar mixture, more or less depleted in oxygen and in hydrogen. It is possible to almost duplicate the observational data, only by assuming that the solar ratio of C/0 is at least as large as 0.66 and that the hydrogen was drastically depleted by an unknown process in the primitive solar nebula. Although none of these two assumptions is at variance with present knowledge, the latter is sufficiently exotic to propose a simpler explanation, namely that comets could be made of interstellar grains relatively unprocessed by heat.
8. Genetic Relations among Meteorites and Planets
Authors: Clayton R. N.
Published: July 2016

On the basis of 180/160 and 170/160 ratios, meteorites and planets can be grouped into at least nine categories, as follows (in order of increasing 1°0): (1) type L and LL ordinary chondrites; (2) type H ordinary chondrites, type HE irons, and CI carbonaceous chondrites; (3) the nakhlites and Shergotty; (4) the earth, moon, and enstatite chondrites and achondrites; (5) basaltic achondrites, hypersthene achondrites, mesosiderites, pallasites and type IRB irons; (6) the ureilites; (7) C2 carbonaceous chondrite matrix, Bencubbin, Weatherford, and Kakangari; (8) C3 carbonaceous chondrites; (9) pallasites Eagle Station and Itzawisis. Objects of one category cannot be derived by fractionation or differentiation from the source materials of any other category, but must represent samples of different regions of an i nhomogeneous solar nebula. The isotopic classification, together with major-element abundances, provides a powerful method for recognition of interrelationships of the various meteorites and their parent bodies.
Ultra-High Resolution Ca II Observations of the LISM
Authors: Welsh Barry Y. , Lallement Rosine , Crawford Ian
Published: July 2016

We report on the status of a long-term program of mapping the velocity structure of the local ISM using ultra-high resolution observations of Call K-line absorption towards nearby B and A-type stars. Absorption components common to the local interstellar cloud (LIC) have been detected in many (but not all) lines-of-sight. Our preliminary results indicate that the local ISM has a complex velocity pattern of inhomogeneous absorption, indicative of a shocked filamentary nature.
Small Scale Structure in Nearby Molecular Gas
Authors: Falgarone Edith
Published: July 2016

Recent observations at high angular resolution of molecular clouds of low column density have revealed the presence of a conspicuous net of small scale filamentary structures, visible in the 12CO rotational lines only. In addition, the existence of unresolved structure at scales as small as ~ 200 AU in space and/or velocity space is inferred from the spectral properties of the 12CO and 13CO emission. The resolved structures are part of the hierarchy of structures observed in molecular gas in the Solar Neighborhood and appear as non self-gravitating elements confined by an ambient pressure P0/kB ~ 3 × 104cm−3 K. We show why these structures might have their origin in the intermittent structures of turbulence in which viscous dissipation is concentrated in space and time.
Intensity Variations of the Soft X-ray Background: the Boundary Structure of the Local Hot Bubble at Low Galactic Latitudes
Authors: Park S. , Finley J.P. , Snowden S.L.
Published: July 2016

42 ROSAT PSPC pointed observations in the Galactic plane (l ~ 4° – 26°) are mosaicked in order to study the spatial structure of the X-ray emitting gas in the Local Hot Bubble (LHB). Degree scale X-ray intensity variations are detected at the ±10% level in the ¼ keV band, which imply a likely influence from a clumpy boundary shell of the LHB in the observed ¼ keV band X-ray background. The possible origins of such a clumpy boundary structure of the LHB are discussed.
A Limit on Galactic Extinction Not Correlated with Far IR Emission
Authors: Finkbeiner Douglas P. , Schlegel David J. , Davis Marc
Published: July 2016

We have reprocessed the IRAS and DIRBE full-sky 100 μm maps, using Hi as a zero-point, to produce a map of Galactic extinction. This map is crosscorrelated with APM galaxy counts over the full APM region, including dusty regions of the sky not used to compute the APM correlation function in Maddox et al.(1990a). The angular correlation function, w(θ), of galaxy counts is computed with and without the extinction correction, and is used to suggest that our map accounts for ~ 90% of the dust-induced correlation in the APM region on scales from 2 – 10°. This is the first time that a limit has been placed on the correlation function of the extinction not represented in a given map.
Simulations of Halo Supernova Remnants
Authors: Shelton R.L.
Published: July 2016

High latitude observations find C3+, N4+, and O5+, while shadowing by intervening hydrogen clouds indicates the presence of soft X-ray emitting gas in the halo of our galaxy. This paper reports on detailed hydrocode simulations of one of the possible source types: isolated supernova remnants evolving in the tenuous ambient medium of the halo. Their O5+ column densities are similar to those observed from the halo. The N4+, C3+, and X-ray properties are also simulated and discussed. The calculations may also be of interest for the Local Bubble, external galaxies, and non-thermal pressure estimations.
The Galactic X-ray Halo
Authors: Pietz J. , Kerp J. , Kalberla P.M.W. , Burton W.B. , Hartmann Dap , Mebold U.
Published: July 2016

We analyzed the soft X-ray background (SXRB) source intensity distribution of the ¾ keV and ¼ keV photons by correlating the public ROSAT PSPC All-Sky Survey data with the new Leiden/Dwingeloo HI Survey. We found that the ¾ keV and ¼ keV distant background source intensity distribution can be modelled by an isothermal (T = 1.5.106 K) disk-like (scale length A1 = 15 kpc) X-ray halo in addition to the radiation of the extragalactic X-ray background.
Magnetic Reconnection and Extraplanar Diffuse Ionized Gas
Authors: Birk Guido T. , Lesch Harald , Neukirch Thomas
Published: July 2016

Many observations indicate the occurrence of ionized gas in the distant halos of galaxies (among them our own). Since photoionization by stars (mainly O stars, young or evolved low mass stars depending on the kind of galaxy) does not seem to be exclusively responsible for the ionization of the hydrogen filaments that should otherwise cool and recombine quickly, the question arises which energy source may result in the quasistationary ionization. We propose that localized magnetic field dissipation in current filaments may contribute to the ionization of the extraplanar halo gas. The dissipated magnetic energy is converted into heat, which then is transferred to the neutrals, resulting in re-ionization on a time scale shorter than the recombination time scale. Quasistatic solutions are characterized by plasma temperatures and densities that agree nicely with the observed values for the diffuse ionized gas component of the Galactic interstellar medium.