bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accretion Disk Instabilities
Authors: Meyer F. 
Published: July 2016

In this article we discuss two instabilities of stationary accretion disks which lead to an understanding of observed light variations in accretion disk systems, the dwarf novae and the rapid burster MXB 17030-335. The accretion disks in these systems avoid instability at the cost of stationarity and perform stable cycles in which sudden changes of the accretion flow lead to corresponding, often dramatic, variations of their accretion luminosity.Figure 1 shows a light curve of U Geminorum. It was discovered In 1855 by J.R. Hind and has become a prototype of the dwarf novae. In these systems an extended time of quiescence of up to several weeks Is followed by a short outburst of a few days during which the luminosity rises by a factor of 30 to 100. The dwarf novae belong to the cataclysmic variables. They are all close binaries In which a white dwarf primary is orbited by a Roche lobe-filling low mass secondary. Through the inner Lagrangian point mass flows over from the secondary and forms a luminious accretion disk around the white dwarf. In the case of the dwarf novae this disk has temperatures below about 10000K in Its outer region. It will be discussed how partial lonizatlon and convection then affect the vertical structure of the disk such that the stationary flow becomes unstable.Fig. 1. Light curve of the dwarf nova U Geminorum. Abszissa in days С [2])
X-Ray Burst Sources
Authors: Melia Fulvio , Joss Paul C. 
Published: July 2016

AbstractType I cosmic X-ray bursts are widely thought to result from thermonuclear flashes in the surface layers of accreting neutron stars. The thermonuclear-flash model is able to account for a wide variety of observed burst phenomena. However, a number of theoretical and observational problems persist. Foremost among these are related to the existence of apparent luminosities in excess of the Eddington limit in many observed bursts. Under circumstances of very high luminosity, the theoretical treatment of radiative transfer and radiatively driven mass loss at the neutron-star surface becomes complex. We discuss the current status of theoretical work in this area and the prospects for developing an understanding of the remaining phenomenological problems: (a) What is the nature of the precursor in some fast transients and of the twin-peak structure observed in some shorter bursts? (b) Do some bursts actually achieve super-Eddington luminosities, and if so, how? (c) What are the characteristics of quasi-static mass loss in the presence of such luminosities? (d) How is the color temperature related to the effective temperature? and, (e) What are the implications concerning the Galactic distance scale?
An Astronomy Degree Course in the U.K.: Syllabus and Practical Work
Authors: Dworetsky M.M. 
Published: July 2016

What is the purpose of an astronomy degree? Why should students wish to take such a course? What will they do after graduation? In what way would such a course uniquely differ from a physics degree with a little astronomy tossed in? And given that we are called upon to provide such a course, what syllabus might we teach? These are some of the questions that occurred to me as I was preparing this paper.One obstacle to giving clear answers is that the higher education systems of various countries differ greatly in structure. As one who was trained in one system (U.S.A.) and who teaches in another (U.K.), I am perhaps in a better position than most to appreciate the differences in approach, and to weigh the advantages and shortcomings of each system. But, as Shakespeare’s Dogberry said, “Comparisons are odorous,” and I do not propose to do this! What I describe refers to current practice in the university system of England and Wales, and I will use my own institution’s long-standing astronomy degree as an example.
Influence of Culture on Understanding Astronomical Concepts
Authors: Othman Mazlan 
Published: July 2016

Culture is defined as a society’s system of values, ideology and social codes of behavior; its productive technologies and modes of consumption; its religious dogmas, myths, and taboos; and its social structure, political system and decision-making process (Coombes, 1985). The cultural environment in which an individual is raised is thus fundamental to the life view with which he perceives his world. Since his world view encompasses ideas of space and time, it is therefore not surprising that his understanding of astronomical concepts is inextricably bound to his cultural envelope.This paper sets out to examine some of the ways cultural complexities affect the understanding of astronomical concepts and thus to make the case for a more realistic approach to the teaching of astronomy in a multicultural society, recognizing the importance of culture and the way students learn (Burger, 1973; Teynolds and Skilbeck, 1976).
Spatial Thinking and Learning Astronomy: The Implicit Visual Grammar of Astronomical Paradigms
Authors: Hill Lon Clay 
Published: July 2016

As several previous speakers have noted, astronomers are a rare breed. Even though we represent the oldest science, we are as rare as poets. The fact that our discipline is so distinct suggests that it should also have its peculiar pedagogical problems. I have been attempting to understand a pervasive element of all astronomical thinking — the use of spatial imagination to link celestial phenomena to terrestrial analogs. My work has two components — a theoretical explication of astronomical thinking and some practical use of these ideas in teaching situations.If one looks at some of the fundamental “facts” discovered by astronomers, we will find that we often do not, in fact, directly verify our discoveries as scientists supposedly do. Primary astronomical “truths” such as the sphericity of the Earth, the heliocentric orbit of the Earth, the identification of the stars as distant suns, and the recognition that galaxies are enormous collections of stars, were not discovered by direct verification. Thus, we note that the Greeks discovered the Earth’s sphericity nearly two millennia before its circumnavigation and that only a few thousand very bright stars in nearby galaxies have been resolved in our largest telescopes. Some of the primary objects of astronomical discourse, then, are not perceptible objects, but objects created by the spatial imagination.
History of the Teaching of Astronomy in American High Schools
Authors: Hoff Darrel B. 
Published: July 2016

Early American colonists had a deep interest in astronomy. Between 1725 and 1764, Nathaniel Ames published the Astronomical Diary and Almanac at Cambridge, Massachusetts. This was a brief, widely-circulated source of astronomical information. It averaged an amazing 60,000 sales per year, while the better known Poor Richard’s Almanac distributed only about 10,000 per year (Noble, 1970).Practical skills were the dominant theme in early colonial schools. The astronomy that was taught dealt with natural phenomena such as phases of the moon, eclipses, and, for practical purposes, navigation and time-keeping. Astronomy was also frequently taught as a part of what we today would call physical geography courses. This practical nature of our culture dominated American schools until about the middle of the 1800’s. Astronomy, as a separate subject, did appear in the curriculum of academies — forerunners of the modern American high school. A popular textbook of this period, An Easy Introduction to Astronomy For Young Gentlemen and Ladies, by James Ferguson, dated 1817, illustrates this point. It is almost completely devoted to the explanation of natural phenomena (Ferguson, 1817). It is a charming book, taught in classic dialogue form between the teacher and his students.
Astronomy and Astrophysics in the Curricula of the German Gymnasium
Authors: Neumann Hans L. 
Published: July 2016

The school system in the Federal Republic of Germany is generally of the classical European type as defined by D. Wentzel in his paper for this colloquium. Children enter school at age 6. After 4 years of primary school they enter secondary schools. The gymnasium type lasts for 9 or 7 years, depending on the state. The final exam (Abitur) entitles the students to go to university.The interest of pupils in learning about astronomy is generally very high. But the usual science or physics teacher’s education in most of our federal states does not include any thorough knowledge of astronomy; physics curricula are overcrowded with traditional matter and more and more modern technical applications, without reducing the time allotted to old topics. Practically speaking, there are very few lessons left that might be used for astronomy teaching.
The Popularization of Astronomy
Authors: Moore Patrick 
Published: July 2016

I suppose it is inevitable that astronomy should be one of the easier sciences to “popularize.” The sky is all around us; even our remote cave-dwelling ancestors must have looked up into the sky and wondered at what they saw there, even though they could have no idea of the nature or scale of the universe. Naturally, they believed the Earth to be supreme, and to have everything else arranged around it for our special convenience. Believe it or not, this point of view is not quite dead even now — and this brings me on to my first point.Some time ago I attended a meeting of the International Flat Earth Society, held in London. Its members believe that the world is shaped like a pancake, with the North Pole in the middle and a wall of ice all around. The meeting was quite remarkable, and participants were totally sincere. Later, I rather ill-naturedly put them in touch with a German society whose members maintain that we live on the inside of a hollow sphere, and I understand that they are still fighting it out; but of course this is quite harmless — and as I have often said, the world would be poorer without its “Independent Thinkers.” But other aspects of eccentric thought are less laudable, and of course I am thinking of astrology, which has experienced a curious revival in recent times.
Take The “A” Train to the Stars
Authors: Pazmino John , Scheuer Sidney 
Published: July 2016

Astronomers, in addition to their scholarly and academic functions, have the mission to bring enlightenment to the people. In the City of New York, astronomers fulfill this mission through the Amateur Astronomers Association. Over the decades, the Association, or AAA, evolved a multi-faceted scheme of public enlightenment in astronomy. Under this scheme, astronomy in New York City has become a freestanding cultural amenity on a par with streetfairs, artshows, plays, and parades.Once a month during the school year, the Association presents a formal public lecture on astronomy. These are convened in the American Museum of Natural History, the ancestral birthplace of the AAA. Occasionally, lectures are featured at a large university in the City for time and place variety. At these lectures, a professional astronomer explains some contemporary topic on a first-year college level, illustrated by slides and viewgraphs. The lectures — and all public activities of the AAA — are free of any charge. Area high schools and colleges employ the AAA lectures as an extra-curricular activity for their students.
Popularization of Astronomy in South India
Authors: Ramakarthikeyan R. 
Published: July 2016

I am presenting this paper only with reference to my city of Madras, the capital of Tamil Nadu, where more than 60 per cent of the population are illiterate.I am an active member of the Madras Astronomical Association and I am the Vice-President of the Vivekananda Astronomy Club, both of which are popularizing astronomy among the masses.Though we have been pleading for the necessity of a planetarium over the last two decades, we got one only in May 1988. But for the last seven years, we designed and set up a mini-planetarium at the Education Pavilion of the Trade Fair Exhibition conducted by the local government every year.
Teaching and Popularizing Astronomy and Space Sciences at the Observatory of the City of Bochum
Authors: Feitzinger J.V. , Hünerbein M. , Kordecki R. , Lemmer U. , Monstadt G. , Prölβ J. 
Published: July 2016

The tasks and aims of the Bochum Observatory are popularization of astronomy and space sciences, and adult education. In general, as a cultural center for natural sciences we must translate scientific nomenclature into the language of the nonspecialist. Astronomy is ideal for presenting the basic facts of scientific methodology and reasoning to the publicA planetarium is the most versatile instrument for teaching basic astronomy and space sciences to the general public as well as to school groups. We take great care to avoid a lecture-like style in the programs. Audience surveys have shown that most visitors don’t want to get the feeling of being educated as in school. Nevertheless, we first have to motivate before we can educate. Instead, most visitors want merely to enjoy astronomy in the pleasant atmosphere of the dome. Consequently, our public planetarium shows contain elements of entertainment. We use many special effects, panoramas, and all-sky projections for a most precise simulation of astronomical phenomena. The audience should get the thrilling impression of witnessing things from close up. For example, they all become passengers on an imaginary spacecraft visiting the rugged terrain of Valles Marineris on Mars, the swirling clouds in Jupiter’s atmosphere, or even the vicinity of a whirlpool-like accretion disc around a supermassive black hole in the core of an active galaxy. We use the potential of the planetarium as an “illusion factory” to increase the visitors’ positive attitude towards astronomy and space travel. Special music, sound, and noise effects add to the impression.
Teaching Astronomy in New Zealand: The Ward Observatory
Authors: Harper Christopher T. 
Published: July 2016

New Zealand is a self-governed, independent nation, a member of the British Commonwealth, and a major center of Polynesian culture in the south Pacific. The country’s two main islands lie between 34° and 47° south latitude, which places New Zealand south of many well known southern observing sites such as Sydney (Australia), Cape Town (South Africa), and Cordoba (Argentina).The population of 3.5 million people inhabit a country slightly larger than the United Kingdom. The astronomical interests of this small population are nourished by no less than 25 local and regional astronomical societies. Amateur astronomers are active in New Zealand. The Royal Astronomical Society of New Zealand coordinates national interests and hosts international activities.
Project STARWALK
Authors: Riddle Bob 
Published: July 2016

Project STARWALK is an Earth/space science program, developed for elementary students in grades 3 and 5 or 4 and 6. The program is designed around the teaching of some basic earth science concepts (Earth’s rotation, revolution, and axial tilt), and their consequences. Classroom lessons are designed to both prepare and follow-up student visits to a planetarium facility. The planetarium is used as an instrument to display models to help the students understand the concepts. There are three visits to the planetarium (fall, winter, and spring).The role of the teacher is to prepare the students for a laboratory experience at the planetarium. This is done by way of the materials provided, and whatever other strategies the teacher deems necessary. There are a variety of activities designed for both pre- and post-reinforcement of the concepts.
The Pre-College Planetarium
Authors: Curran Brendan 
Published: July 2016

The Bronx High School of Science is a public school in the New York City school system. It is a specialized school whose students are selected on the basis of a competitive exam. Our planetarium projector was installed out his spring, so many of these suggested activities are still in development stage.In the high school setting, the planetarium has a dual role as a teaching tool and as a motivational tool. The planetarium is used in the Astronomy and Astrophysics course, an advanced elective. This use permits a detailed study of the sky, which is otherwise difficult in New York City. Students who are familiar with thinking in two dimensions often have trouble making the transition to the three dimensions required in astronomy. The planetarium is an invaluable tool to develop students’ spatial orientation. Further, the planetarium generates tremendous enthusiasm.
Algol, Beta Lyrae, and W Serpentis: Some New Results for Three Well Studied Eclipsing Binaries
Authors: Guinan Edward F. 
Published: July 2016

AbstractThe properties of the eclipsing binaries Algol, Beta Lyrae, and W Serpentis are discussed and new results are presented. The physical properties of the components of Algol are now well determined. High resolution spectroscopy of the H-alpha feature by Richards et al. and by Gillet et al. and spectroscopy of the ultraviolet resonance lines with the International Ultraviolet Explorer satellite reveal hot gas around the BBV primary. Gas flows also have been detected apparently originating from the low mass, cooler secondary component and flowing toward the hotter star through the Lagrangian L1 point. Analysis of 6 years of multi-bandpass photoelectric photometry of Beta Lyrae indicates that systematic changes in light curves occur with a characteristic period of ≃275 ± 25 days. These changes may arise from pulsations of the B8II star or from changes in the geometry of the disk component. Hitherto unpublished u, v, b, y, and H-alpha index light curves of W Ser are presented and discussed. W Ser is a very complex binary system that undergoes complicated, large changes in its light curves. The physical properties of W Ser are only poorly known, but it probably contains one component at its Roche surface, rapidly transfering matter to a component which is embedded in a thick, opaque disk. In several respects, W Ser resembles an upscale version of a cataclysmic variable binary system.
Mass Flow in Interacting Binaries Observed in the Ultraviolet
Authors: Kondo Yoji 
Published: July 2016

AbstractRecent satellite observations of close binary systems show that practically all binaries exhibit evidence of mass flow and that, where the observations are sufficiently detailed, a fraction of the matter flowing out of the mass-losing component is accreted by the companion and the remainder is lost from the binary system. The mass flow is not conservative. During the phase of dynamic mass flow, the companion star becomes immersed in optically-thick plasma and the physical properties of that star elude close scrutiny.
Formation and Evolution of Low-Mass Algols
Authors: Yungelson L.R. , Tutukov A.V. , Fedorova A.V. 
Published: July 2016

AbstractWe discuss the origin, evolution and fate of low-mass Algols (LMA) that have components with initial masses less than 2.5 M0. The semi-major axes of orbits of pre-LMA do not exceed 20-25 R0. The rate of formation of Algol-type stars is ~ 0.01/year. Magnetic stellar winds may be the factor that determines the evolution of LMA. Most LMA end their lives as double helium degenerate dwarfs with M1/M2 ~ 0.88 (like L870-2). Some of them even merge through angular momentum loss caused by gravitational waves.
The Evolution of Moderately Close and Moderately Wide Binaries
Authors: Eggleton P.P. , Tout C.A. 
Published: July 2016

AbstractWe discuss evolutionary processes in binaries where the primary becomes a red giant with a deep convective envelope before it fills its Roche lobe. Such binaries (late Case B or late Case C, if they evolve conservatively) ought to suffer drastic mass transfer, on a hydrodynamic timescale. In some circumstances this may lead to a common envelope, spiral-in, and finally either a very short-period binary or coalescence. But there appear to be other circumstances in which the outcome is an ordinary Algol, or a wide binary with a white dwarf companion as in Barium stars and some symbiotics. We try to demonstrate that stellar-wind mass loss, enhanced one or two orders of magnitude by tidal interaction with a companion, can vitally affect the approach to RLOF, and indeed may prevent RLOF in binaries with periods over 1000 d. Such mass loss is probably accompanied by angular momentum loss, by magnetic braking combined with tidal friction. The result is that it will not be easy to predict definitively the outcome of evolution in a given zero-age binary.
Fundamental Parameters of the W Serpentis Stars
Authors: Andersen J. , Nordström B. 
Published: July 2016

AbstractApplication of digital cross-correlation spectroscopy to the spectra of the W Serpentis binaries SX Cas and RX Cas has allowed an accurate determination of the orbits and rotations of the (mass-losing) K-subgiant secondary components. The distortion of the primary radial-velocity curves due to the influence of the prominent accretion disks in these systems has been modelled to first order. This enables us to estimate K1 , and thereby the mass ratio q ≈ 0.30, to within ~±20%. The absolute radii of the secondaries are derived independently from the observed rotations and periods, assuming synchronous rotation. They show that the stars fill their Roche lobes, or at least very nearly so. Rough fits to the available photometry shows both primaries to be unevolved mid-B stars; that in RX Cas appears completely obscured by the disk. Preliminary spectroscopic data for W Ser and W Cru show some promise for similar analyses of these systems.
High Signal-To-Noise Ratio - the Spectroscopic Key to Algol Systems
Authors: Tomkin Jocelyn 
Published: July 2016

AbstractThe usefulness of high signal-to-noise-ratio spectra for both radial-velocity and abundance studies of Algol systems is emphasised. It is shown that division by a hot star is a worthwhile step in pursuit of this objective. A preliminary analysis of high signal-to-noise-ratio, red and near-infrared, Reticon observations of R CMa shows that its primary has solar CNO abundances within the 0.3 dex observational error. The low-mass (0.17 m⊙) secondary of this Algol system must have lost a large fraction of its original mass. Some of this material would have been extensively processed during the secondary’s main-sequence lifetime and would therefore have had a highly non-solar CNO-abundance distribution. The lack of serious contamination of the primary’s abundances is consistent with most, but not all, plausible mass-transfer scenarios.
Concluding Remarks
Authors: Koch R. H. 
Published: July 2016

How does one examine a colloquium event so as to gauge whether it has been a success? I don’t know of a canonical way to do this but one obvious possibility re-studies the scientific goals proposed by the SOC. When I do do this, I find that the formal papers and the conversation have at least touched on every one of the enumerated topics.I am going to make my own estimate by describing three precepts in the following sections and by drawing a conclusion after each of them. I make no claim that this procedure is novel. We came to the meeting with our individual funds of background knowledge according as we are, variously, specialists in some sub-topic of Algols or are stellar generalists, who know at least something broadly about these stars. I think that I fall into the latter category and this flavors my remarks.
The Gravity-Darkening of the Main-Sequence Components of Spectral Types A, F and G in Detached Close Binary Systems
Authors: Nakamura Y. , Kitamura M. 
Published: July 2016

Abstract.From analysis of the photometric ellipticity effect in seven well-understood detached close binary systems, empirical values of the exponent α of gravity-darkening have been practically deduced for eleven main-sequence components of spectral types A, F and G which should cover the range of structural change (from radiative to convective) in stellar atmospheres. The result indicate that values of the exponent diminish gradually with decreasing effective temperatures from α ~ 1.0 for radiative atmospheres with T > 8500 K to α =0.2 ~ 0.3 for convective atmospheres with T < 6500 K, in spite of some uncertainty in the reflection correction process.