bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Contribution of Amateur Astronomers to Astronomy Education
Authors: Iwaniszewska Cecylia 
Published: July 2016

I would like to dedicate this paper to the memory of my husband, Henryk Iwaniszewski, an astronomer working in radio astronomy and electronics, who until his untimely death seven years ago had been very active as president of our local branch of the Polish Amateur Astronomers Association. He was especially keen about introducing astronomy to the general public.I want to speak here mainly, but not exclusively, about the IAU Colloquium No. 98, “Contribution of Amateur Astronomers to Astronomy,” which was held in 1988 in Paris. First of all, some definitions. Thomas Williams of the American Association of Variable Star Observers (AAVSO), from Houston, Texas, introduced at the conference several criteria for identification — first of astronomers, and then of professionals and amateurs. According to Williams:
Extragalactic Objects: An Example of Popularizing Astronomy for the Amateur Astronomer
Authors: Feitzinger J.V. 
Published: July 2016

The handbook Astronomy (Handbuch für Sternfreunde), edited by G.D. Roth, will soon appear in its fourth edition. Newly written by 25 authors, the two volumes contain an additional chapter: Extragalactic Objects. The intention of my 50-page contribution to these volumes is to show the amateur astronomer that extragalactic work is not disappointing, ending in the northern sky with a fuzzy picture of the Andromeda Nebula.The former editions of Roth’s handbook were mainly characterized by the statement that the observation of extragalactic objects is beyond the capabilities of the amateur. In the last ten years the situation has drastically changed, especially because of new photographic techniques and sensitive emulsions and the availability of CCD’s even for amateur astronomers. Small telescopes are no hindrance to doing interesting extragalactic work.
The Popularization of Astronomy in Mexico
Authors: Fierro Julieta 
Published: July 2016

Mexican professional astronomers have a great task ahead if they want to popularize astronomy. We are very few and the country has great educational needs, with 4 years of elementary school being the average educational level.In order to overcome this challenge, the Institute of Astronomy of the National University has popularized astronomy using the following resources: 1) publications, 2) public lectures, 3) advice to museums and planetariums, 4) radio and television interviews, and 5) courses.
Astronomy Courses for Adults in Sydney, Australia
Authors: O’Byrne J.W. 
Published: July 2016

The University of Sydney has been associated with adult education courses for the general public for at least 70 years and astronomy has often been a part of this activity. Since 1976, these courses have been conducted by a succession of graduate students from the Astronomy and Astrophysics departments within the university. The courses were a part-time activity conducted with limited resources, but served as useful teaching experience. This arrangement continued until the end of 1987 when I left the university. I am pleased to report that this activity is considered sufficiently important to be continued by the permanent academic staff.Here I seek to briefly report on these astronomy courses by describing those that I conducted at the university over the last five years. I should firstly acknowledge the work of Dr. Graeme White in particular, for his earlier courses and continuing interest. Also, this discussion should be placed in context by recognizing that other astronomy courses are run in Sydney by professional and amateur astronomers through local evening colleges and other organizations. These vary in format, with many of the amateur-run courses emphasizing the practical aspects of sky observing. The displays and facilities provided by the Sydney Observatory also play an important role. Each activity helps to meet the demand in the Sydney region for astronomical education and thereby undoubtedly serves the interests of Australian astronomy.
The Hα Emitting Regions of the Accretion Disks in Algols
Authors: Peters G. J. 
Published: July 2016

AbstractThe circumstellar plasma that produces Hα emission in Algol binaries has been investigated using phase-resolved, high dispersion data acquired from CCD and image tube detectors. Results are summarized in this paper, including discussions of the disk geometry and size, asymmetry in the distribution of material, long-term or non-phase dependent variability, mass outflow, the mean electron density, and how the latter properties vary with the system’s period or location in the r - q diagram. Five systems which display permanent emission with periods ranging from 4.5 to 261 days (SW Cyg, UX Mon, TT Hya, AD Her, and RZ Oph) are intercompared. If P < 4.5 days, no permanent disks are observed, while if P > 6 days, stable disks with only slight long-term variations in their Hα brightness are seen. The most variable systems appear to be those in the 5 - 6 day range, but the star’s position in the r - q diagram has the largest influence on its behavior. The trailing side of the accretion disk, where the gas stream impacts the inner disk, is usually brighter, and the leading side is often times more extended. The disk extends out to at least 95%of the Roche surface of the primary and is highly flattened (≤Rp). Mass outflow near phase 0.5 is commonplace.
Photometric Effects of Accretion Disks in Long-Period Eclipsing Binaries
Authors: Olson Edward C. 
Published: July 2016

Accretion disks are invoked in a variety of astrophysical settings, ranging from stellar-mass black holes to active galactic nuclei. There is now little doubt that true accretion disks can also occur in binaries containing non-degenerate stars (Peters 1980; Plavec et al. 1984; Polidan 1987). In this paper, I will discuss some of the properties of disks observed photometrically in the long-period systems KU Cyg and RZ Oph.The most intensively-studied disks are of course those in cataclysmic binaries. Accretion disks in such binaries are thought to have the classical ′alpha′ structure of Shakura and Sunyaev (1973), in which viscous dissipation arising from differential rotation converts gravitational potential energy to thermal energy in supplying the disk luminosity. This physical process requires that the viscous time scale be comparable to the radiative decay time of the disk (Pringle 1981). Most of the disk′s volume is optically thick, so disk luminosity is estimated by integrating black-body or stellar atmospheric fluxes over the disk (see Kriz and Hubeny 1986 for qualifications).
Radio Emission from Selected Algol Systems
Authors: Umana G. , Catalano S. , Rodonó M. , Gibson D. M. 
Published: July 2016

Radio emission from close binary systems has long been detected in Algol and other systems. RS CVn systems have been found to be the most powerful and active. The RS CVn binaries are also known to show strong chromosferic and transition region emission line fluxes, that are one or two orders of magnitude higher than those from single stars of similar spectral type. This enhanced activity seems to be connected to the rapid rotation due to the tidal interaction in the system. The Algol binaries are semi-detected close binary systems formed by an early type main sequence primary and a late type giant secondary, while in the RS CVn both components are late type stars of about the same mass, the secondary being a giant or subgiant.The Algol binaries and RS CVn differ also in their evolutionary history. However, since the spectral type and probably the internal structure of the secondary components of Algols appear to be similar to that of the secondaries of RS CVn systems, and they both are synchronous fast rotators in close binaries, we would also expect that the secondaries of Algol systems to show some kind of activity.
Duplicity on the Main Sequence
Authors: Herczeg T. 
Published: July 2016

AbstractA review paper or a lecture like the following one, will best serve ‘its’ conference by giving an overview of the basic facts, and an impartial review of current debates, also by trying to point out some apparently crucial questions whose solutions, we hope, will determine the line of future research.Because these stars are essentially unevolved, beyond the topic of multiplicity on the Main Sequence looms the fundamental problem of the formation of binary star systems. Thus we are going to concentrate on the following questions: the fraction of stars that are formed in binary and multiple systems, the distribution of mass ratios for unevolved systems, the role of very wide pairs and the smallest known stellar or substellar masses. We will pay special attention to nearby binary stars. On the other hand, we do not have the space to discuss in any detail the binaries in extragalactic systems, in the upper regions of the HR-diagram; they are practically all evolved systems.
Fission Sequence and Equilibrium Models of Rigidity Rotating Polytropes
Authors: Hachisu Izumi , Eriguchi Yoshiharu 
Published: July 2016

AbstractEquilibrium sequences of self-gravitating and polytropic stars including binary stars are computed for various polytropic indexes. We find a fission sequence from an ellipsoidal configuration to a binary by way of dumb-bell equilibrium.
Fission Candidates Among Detached Close Binaries
Authors: Ott H.-A. 
Published: July 2016

AbstractA comparison between results of model calculations and observed properties of close, but detached low mass binaries with Main Sequence primaries shows statistical trends, which seem to support fission origin for some of these objects: the mass-momentum relation, the relation between mass ratio and separation and the relation between mass ratio and synchronisation speak in favour of close initial separations and small mass ratios of the components.
VV Orionis: A Well-Behaved Early-Type Eclipsing Binary System
Authors: Chambliss Carlson R. 
Published: July 2016

AbstractVV Orionis is a detached eclipsing binary system consisting of stars of spectral types BI V and B4 V with a period of l.d4854. There is also a third component whose orbital period about the eclipsing pair is about 120 days. In recent years there have been several new photoelectric and spectroscopic investigations of this system, and the results of these are compared. Both the geometric and photometric orbital elements appear to be well determined. VV Ori A appears to be of normal size and mass for its spectral class, but VV Ori B seems to be somewhat smaller than would be expected for a normal B4 V star. Linear limb-darkening coefficients are derived for VV Ori A, and these are in good agreement with theory. This system is of particular importance, because it is only one of very few early-type systems for which reliable limb-darkening coefficients can be expected to be obtained. The contribution of the light of the third component to the system has also been determined, and it appears most likely that VV Ori C is a star of spectral type A3 V.
Photometry of the RS CVn Type Eclipsing Binary UV Piscium
Authors: Rao P. Vivekananda , Sarma M. B. K. 
Published: July 2016

AbstractThe analysis of the UBV photoelectric study of the short period RS CVn eclipsing binary, UV Psc, has suggested that the primary is a transit with ɵe = 27°, i = 88.°5, and k = 0.75. The spectral type and luminosity of the hotter component is estimated to be G4-6V and that of the cooler component to be K.0-2V. Absolute dimensions for the components of UV Psc were derived by combining the present analysis with that of the spectroscopic analysis given by Popper.The out-of-eclipse observations have showed large amount of scatter and an investigation of this showed that hotter component could be an intrinsic variable. No periodicity for this variation has been fixed due to lack of sufficient data.
Variable, Optically Thick, Hot Plasma Observed in Interacting Binaries
Authors: Kondo Y. , McCluskey G. E. , Parsons S. B. 
Published: July 2016

AbstractWe report recent International Ultraviolet Explorer (IUE) observations of two interacting binaries, R Arae and HD 207739. The ultraviolet spectra indicate the presence of optically-thick, variable hot plasma in those binary systems. These two binaries may belong to a class of binaries that are currently undergoing a rarely observed and probably short-lived phase in their evolution. Their properties are compared with those of two other interacting binaries, U Cephei and ß Lyrae.
Periods Ranging From 5 to 1500 Days in the Anticorrelated Moving Lines of SS 433
Authors: Frasca S. , Ciatti F. , Mammano A. 
Published: July 2016

AbstractSome tens of harmonic components are found in the moving lines of SS 433, leaving a standard deviation of 0.002 in Z units, that is comparable to the observational error.Ten harmonics appear anticorrelated in the two branches, among which those at 80,155, and 1500 days are also strong. Their behaviour indicates changing structure in the ejecting mechanism.No secular change is occurring in the precessional 163-day period beyond the estimated error of 5 x 10-5 d-1. No periodicity occurs in beam velocity. One quarter of cases of (Z1 + Z2) are found outside their mean value by more than 5σ. This implies either variable beam velocity or absence of strict anti-parallelism.
Late Stages of the Evolution of Close Binaries
Authors: De Loore C. , Sutantyo W. 
Published: July 2016

AbstractClose binaries can evolve through various ways of interaction into compact objects (white dwarfs, neutron stars, black holes). Massive binary systems (mass of the primary M1 larger than 14 to 15 M0) are expected to leave, after the first stage of mass transfer a compact component orbiting a massive star. These systems evolve during subsequent stages into massive X-ray binaries. Systems with initial large periode evolve into Be X-ray binaries.Low mass X-ray sources are probably descendants of lower mass stars, and various channels for their production are indicated. The evolution of massive close binaries is examined in detail and different X-ray stages are discussed. It is argued that a first X-ray stage is followed by a reverse extensive mass transfer, leading to systems like SS433, CirXl. During further evolution these systems would become Wolf-Rayet runaways. Due to spiral in these system would then further evolve into ultra short X-ray binaries like CygX-3.Finally the explosion of the secondary will in most cases disrupt the system. In an exceptional case the system remains bound, leading to binary pulsars like PSR 1913 +16. In such systems the orbit will shrink due to gravitational radiation and finally the two neutron stars will coalesce. It is argued that the millisecond pulsar PSR 1937 + 214 could be formed in this way.A complete scheme starting from two massive ZAMS stars, ending with a millisecond pulsar is presented.
Analysis of 11 Late-Type Close Binary Systems
Authors: Lfung K. C. , Zhai D. S. , Zhang R. X. , Liu Q. Y. , Zhang J. T. , Yang Y. L. 
Published: July 2016

AbstractThis is a preliminary report on the joint research project between 3 observatories: Beijing, Yunnan, and Behlen Observatories from China and the United States. The systems we have been dealing with are primary of late spectral types and with short periods. Most.of the observations were secured from the observatories in China. The computational analysis is carried out in University of Nebraska, Lincoln. The photometric solutions are based on the Wilson and Devinney method. Out of 11 systems analyzed 6 of them: AO Cam. ER Ori. BX Peg, BB Peg, U Peg, and SW Lac are found to be contact systems. All of them are having their primary eclipses at occultation. Therefore they can be classified as W-type WUMa systems. They also show other W-type characteristics.
Fragmentation and Distribution of Asteroids
Authors: Dohnanyi Julius S. 
Published: July 2016

As a result of mutual inelastic collisions, frequent on a geologic time scale, the mass distribution of asteroids undergoes constant change. Using a simplified velocity distribution for asteroids, the redistribution of their masses caused by collisions can be mathematically modeled as a stochastic process and the distribution of asteroidal masses can then be obtained as the solution. This paper is a review of recent progress on this problem.The most detailed discussion of this problem considers the influence of the following collisional processes on the asteroidal mass distribution: (1) loss of asteroids by catastrophic breakup, (2) creation of new objects from the fragments of a catastrophically disrupted one, (3) erosive reduction in the masses of individual asteroids, and (4) erosive creation of new objects (i.e., production of secondary ejecta during erosive cratering by projectiles not large enough to catastrophically disrupt the target object). The main result is that after a sufficiently long period of time the population of asteroids may reach a quasi-steady-state distribution, regardless of the initial distribution. This final distribution is a product of a slowly decreasing function of time by a power law of index 11/6 for masses smaller than the largest asteroids. For the largest asteroids, an additional factor is included that expresses the influence on the distribution of the absence of masses larger than those observed. The observed distribution of bright asteroids from the McDonald asteroidal survey and that of faint ones from the Palomar-Leiden asteroidal survey are each individually consistent with the theoretical distribution, although they differ from each other by a numerical factor.
Structure of Comets and the Possible Origin of Faint Asteroids
Authors: Vanýsek V. 
Published: July 2016

It is shown that very old and still active icy-conglomerate or “clathrate” cometary nuclei may exist at the outer boundary of the asteroidal belt and belong to the group of relatively stable “outer” short-period comets of which only a small fraction have been discovered or recognized as cometary objects.hich is much more convincing, it explains their brightness dependence on the heliocentric distance.The search for these comets among very faint asteroids with the mean motion μ ≤ 600”, and the study of their behavior could be very important to our knowledge about the final stage of cometary nuclei.
Precision of Ephemerides for Space Missions
Authors: Marsden B.G. 
Published: July 2016

One of the most extensive programs of systematic observations of minor planets currently being conducted is that at the Crimean Astrophysical Observatory. The observed positions, together with the residuals from the predictions in the annual Ephemeris volumes, have been listed in the Minor Planet Circulars for several years now; and inspection of the residuals yields information about the accuracy of minor planet ephemerides as a whole.The observations are made using a 40 cmf/4 double astrograph, the limiting magnitude being about 18. Between June 1968 and October 1969, corresponding to one synodic period of an average minor planet, about 40 percent of all the numbered objects were observed. These observations may be regarded as reasonably representative of all the planets. Observations were made of 60 of the objects with numbers in the 100’s and only 29 of those in the 1100’s, but in general the distribution was surprisingly uniform.
X-Ray Spectra from Highly Ionized Iron and Nickel
Authors: Schwob J. L. , Fraenkel B. S. 
Published: July 2016

X-ray radiation is obtained from a point plasma produced by pinch effect Cohen et al. (1968) in a vacuum spark similar to that used by Lie and Elton (1971) with a 220 kA peak current. The extremely dense and hot minute plasma appears at a distance of 0.5 to 1 mm from the anode tip and has maximum dimensions of a few microns.The spectroscopic observations are performed by means of a focusing Cauchois spectrometer so as to avoid effects of fluctuations in the source position.
Identifications of Emission Lines in the EUV Solar Spectrum
Authors: Jordan Carole 
Published: July 2016

In this brief review of solar line identifications the progress made since the previous conference in this series, which was held in Maryland in 1968, will be discussed.Only lines which appear in emission when seen in the solar disk will be included, thus excluding lines from low stages of ionization at wavelengths of above about 2000Å which can appear in emission at the limb.It is convenient to divide the solar spectrum between about 1.5 Å and 2300 Å into wavelength regions, since the various types of transitions which will be discussed tend to appear over restricted wavelength ranges.
Spectrograms of α Lyra and β Cen in the Region of 2000–3800 Å
Authors: Gurzadyan G. A. , Ohanesyan J. B. 
Published: July 2016

During the flight of the spaceship ‘Salyut’, manned by the spacemen G. T. Dobrovolsky, V. N. Volkov, and V. I. Patsaev, nine spectrograms of α Lyra and six spectrograms of β Cen were obtained with the help of the ‘Orion’ system, in the range of wavelengths 2000–3800 Å and with a spectral resolution of about 5 Å near 2600 Å.The ‘Orion’ system is a telescope of the Mersenn system, with a large mirror of 280 mm diameter, and a slitless spectrograph of the Wadsworth system with a diffraction grating (Figure 1). The dispersion is 32 Å mm-1. The spectrograms were recorded on a perforated photographic film, 16 mm wide, covered with emulsion of the UFSH-4 type.
Polarimetry of Symbiotic Stars
Authors: Piirola V. 
Published: July 2016

ABSTRACTFive symbiotic stars have been observed for linear polarization (UBVRI) in September 1981. Three systems, CH Cyg, CI Cyg and AG Peg show intrinsic polarization while in the case of Z And and AX Per the observed polarization seems to be mostly of interstellar origin. The position angle of polarization of CI Cyg and AG Peg rotates strongly vs. wavelength, as observed also for CH Cyg in 1977-80. The polarization of CH Cyg has decreased since May 1980, especially in the I, R and U bands, so that the maximum polarization is now in the blue (PB ~ 0.3 %). Probably we are monitoring the formation, growth and disappearance of dust particles in the atmosphere of this star. Two related systems, PU Vul (Nova Vul 1979) and R Aql (Mira) have polarization behaviour rather similar to that of symbiotic stars which suggests that the M type giant present in these systems is responsible for most of the intrinsic polarization.
The Evolutionary Status of the Secondaries of Cataclysmic Binaries
Authors: Ritter H. 
Published: July 2016

ABSTRACTIt is shown that the secondary components of cataclysmic binaries with orbital periods of less than ~10 hours are indistinguishable from ordinary low-mass main-sequence stars and that, therefore, they are essentially unevolved. On the other hand, it is shown that, depending on the mass ratio of the progenitor system, the secondary of a cataclysmic binary could be significantly evolved. The fact that nevertheless most of the observed secondaries are essentially unevolved can be accounted for by assuming that the probability distribution for the initial mass ratio is not strongly peaked towards unity mass ratio.
Star-Planet Systems and Their Relation to Low Mass Cataclysmic Variables
Authors: Livio Mario 
Published: July 2016

ABSTRACTWe investigate the possibility of forming a low mass cataclysmic binary from a star-planet system. Using certain simplifying assumptions it is shown that an analytic solution for the evolution of the separation can be obtained. The fate of the system is determined by the competition between mass loss and accretion drag. While it is found that some fine tuning is required for the formation of a close binary, such a binary can still be formed, for parameters that are not too exotic.
A Preliminary Analysis of the Pulsating Extreme Helium Star V652 Her (BD+13°3224)
Authors: Jeffery C.S. , Heber U. , Hill P.W. 
Published: July 2016

AbstractA preliminary fine analysis of the atmosphere of the pulsating extreme star V652 Her (=BD+13°3224) is reported. The mean effective temperature and temperature variation have been determined from the ionisation equilibria of Si and N. Both of these elements are strongly overabundant, whilst C appears to be underabundant.