bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation Hydrodynamics in Pulsating Stars
Authors: Stellingwerf Robert F.
Published: July 2016

The topic of this review encompasses all aspects of pulsation theory, for the radiation field is never negligible in stellar stability problems, on the contrary, it is usually the primary destabilizing factor through its thermal effects, and modifies the envelope structure and stability through its dynamic effects. The impossibility of a general review of such a broad topic is apparent, and I will concentrate in this talk on the most striking aspect of pulsating stars: nonlinear effects in the outer layers. To focus the discussion, I will address primarily two problems of current interest: shock development driven by the pulsating velocity field, and time dependent turbulence in the ionization zones. The emphasis will be on methodology rather than specific problems and developments.
The Physics of Supernovae
Authors: Woosley S.E. , Weaver Thomas A.
Published: July 2016

Presupernova models of massive stars are presented and their explosion by “delayed neutrino transport” examined. A new form of long duration Type II supernova model is also explored based upon repeated encounter with the electron-positron pair instability in stars heavier than about 60 M⊙. Carbon deflagration in white dwarfs is discussed as the probable explanation of Type I supernovae and special attention is paid to the physical processes whereby a nuclear flame propagates through degenerate carbon.
The Early Evolution of Supernova Remnants
Authors: Fransson Claes
Published: July 2016

In his review in 1972 Woltjer [1] divided the evolution of supernova remnants into three different phases, the free expansion phase, the adiabatic Sedov phase and the radiative phase, when cooling of the gas becomes important. The first of these was only briefly discussed and little connection between the supernova explosion and the remnant phase was made. The reason for this is also easy to understand in view of the difficulty of determining the type of explosion even for well-known, young remnants like Cas A, Tycho, Kepler and the Crab remnant.

This situation has changed considerably during the last five years or so, mainly due to observations with new instruments like VLA, IUE and Einstein. With these, as well as large optical and infrared telescopes, the information about the supernova explosion and the early evolution of the supernova remnant has increased dramatically, and a more or less new picture of the explosion has emerged. Instead of a free expansion into a virtual vacuum, with few observational consequences, the supernova undergoes a complex interaction with its immediate surroundings, with a wealth of observational information. In this stage both the structure of the supernova ejecta and the circumstellar medium is crucial for the observational properties. Perhaps, the most interesting aspect of it is that we in this way can bridge the gap between the supernova explosion and the remnant stage.
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

Type 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?
Interpretation of Extragalactic Jets
Authors: Norman Michael L.
Published: July 2016

The subject of this paper is the interpretation of extragalactic radio jets. In this paper I will focus on what we have learned about the nature of extragalactic jets on the basis of model calculations. By model I mean any set of calculations, whether analytic, semi-analytic or numerical, which, when carried through from their respective assumptions to their internally self-consistent conclusions, help place constraints on the physical parameters and processes in the jets and their associated radio lobes. In this field, a visual inspection of a modern high-resolution radio interferometric observation (see review by PERLEY in these proceedings) often leads to statements like “that looks just like such and such in Landau and Lifschitz; I betcha that’s what’s going on!” This I call a speculation, or, at best, a hypothesis. I am addressing here the step beyond hypothesis, namely modeling, which is necessary to confront not only the object in question, but more importantly, the hypothesis itself. In the end, we will remember only the hypotheses.
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.
Astronomy for Business Students: Space Industrialization and the Commercial Potential of Space Technology
Authors: Philips James R.
Published: July 2016

When teaching science to nonmajors lacking an interest in science, two major goals are to stimulate their interest and to provide these students with information and scientific skills useful in their lives and careers. Business students now comprise over 23 per cent of the undergraduates in America, and they generally view science, including astronomy, as not relevant to their lives and careers. I find the students entering my introductory astronomy course for business students expect a pictorial tour of the universe, and are unhappy when asked to calculate redshifts in the laboratory or to attend an extra class meeting for telescope observing. Astronomy is not what they have come to a business college to learn, but they have a laboratory-science requirement to fill for their degree.
Teaching University Astronomy an a Megalopolis: The “Astrotino” Approach
Authors: Keyes Charles D. , Plavec Mirek J.
Published: July 2016

About every other undergraduate student eventually takes the UCLA elementary astronomy class Astronomy 3, and the two of us have been teaching about 1,000 of them every year. We will not repeat complaints about their poor and patchy high-school preparation in science, but we must mention it as an important phenomenon in U.S. education. The European system appears to be preferable, in which mathematics, chemistry, physics, and biology are mandatory and taught every year, although only 3 hours per week. It prevents large memory gaps and the spiral-wise parallel development in all four subjects makes it possible to teach on a higher level every subsequent year.
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).
On Creationism in the Astronomy Classroom
Authors: Sakimoto Philip J.
Published: July 2016

Recently in the United States, a small but vocal group of citizens has been promoting a view known as “creationism,” the assertion that the universe and everything in it was created in six days by divine fiat as suggested by a literalist interpretation of the Christian Bible. In a now common variant, “scientific creationism” or “creation-science,” they assert further that this version of creation is proven true on “scientific” evidence alone, independent of any religious underpinnings. Legislation requiring the teaching of creation-science alongside of evolution in the public schools has been proposed in over twenty states; in Louisiana and Arkansas such legislation was passed, although it was later struck down by federal courts as a violation of the separation of church and state.
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.
Astronomy Activities of the American Association of Physics Teachers
Authors: Dukes Robert J.
Published: July 2016

The American Association of Physics Teachers (AAPT) was founded in 1930 by members of the American Physical Society whose main interest was the teaching of physics. Since then its primary goal has remained the improvement of physics teaching at all levels. The Association publishes two journals (American Journal of Physics and The Physics Teacher) and a bulletin (The Announcer). The American Journal of Physics is intended for papers concerning physics teaching at the level of colleges and universities in the United States while The Physics Teacher is concerned primarily with introductory physics, including high-school courses. Two national meetings are held annually as well as numerous regional meetings.
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 public

A 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.
Planetarium Activities in the Federal Republic of Germany
Authors: Keller H.-U.
Published: July 2016

The planetarium was invented by the German engineer Walther Bauersfeld of the Carl Zeiss Company in 1919, and the first projection-planetarium in the world was installed in the Deutsches Museum in München (Munich) 1923. Most of the German planetariums were destroyed during World War II. Today, nine major planetariums with dome diameters greater than 15m are in operation in the following cities in F.R. Germany; the numbers in brackets are the year of opening, the dome size and the seating capacity: West Berlin (1965; 20 m; 320), Bochum (1964; 20 m; 300), Hamburg (1933; 20.6 m; 270), Mannheim (1984; 20 m; 287), München (1925; 15 m; 156), Münster (1981; 20 m; 280), Nürnberg (1961; 18 m; 255), Stuttgart (1977; 20 m; 277), and Wolfsburg (1983; 15 m; 148).
Algol, Beta Lyrae, and W Serpentis: Some New Results for Three Well Studied Eclipsing Binaries
Authors: Guinan Edward F.
Published: July 2016

The 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

Recent 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

We 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

We 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

Application 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

The 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.
High Mass Ratio Contact Binaries: Recent Evolution into Contact?
Authors: Hrivnak Bruce J.
Published: July 2016

Recent theories of the origin and evolution of contact binaries suggest that the two stars evolve into contact through angular momentum loss (AML; Mochnacki 1981, Vilhu 1982). When in contact, the system then evolves toward smaller mass ratio through mass transfer from the secondary to the primary component (Webbink 1976, Rahunen and Vilhu 1982). Most contact binaries have mass ratios of 0.3 to 0.5.
Activity and Secondary Minimum of RZ Eridani
Authors: Kviz Z.
Published: July 2016

RZ Eridani is an eclipsing binary star with Algol-type light curve of rather long period of 39.28 days. As this star exhibits emission lines of Ca 11 H and K it was classified also as RS CVn type. RZ Eri has been occasionally observed with the GENEVA photometric system with 40cm and later 70cm Swiss telescope at La Silla, Chile, since 1977 mainly for obtaining a complete light curve and for detecting the secondary minimum. The observation showed, that the brightness outside minima really varies as the RS CVn stars usually do. The secondary minimum has been detected at the phase 0.67. Apart from that, the variation of the brightness outside the minima occasionally drops for a short time (about one day or even less). These drops may be due to rotation and uneven distribution of active regions on the surface of the secondary or by the gas streams between the two components. The variation of the light outside minima is certainly not caused by the primary component, because such jumps in the brightness were detected during the total eclipse, when the primary component is not visible. This star certainly deserves more both photometric and spectroscopic attention. Preliminary search for periodicities by G. Burki showed that apart from the orbital period no other periods within the range of days are present. Further details will be published later elsewhere.
Rapid Oscillations of CI aur and AQ TAU
Authors: Xuefu Liu , Zhian Li
Published: July 2016

Photoelectric (UBV) observations were made with the 91-cm telescope of McDonald Observatory of CI Aur (P=lḍ870) and AQ Tau (P=lḍ216) from November 1984 to January 1985. The light-curves showed obvious disturbances, including apparent "flickering", but do not appear to show secondary minima. There is a "dip" in each light-curve near phase 0P1. Average values of the colour indices outside eclipse were (B-V)=0ṃ860, (U-B)=0ṃ432 for CI Aur and 1ṃ15 and 0ṃ59 , respectively, for AQ Tau. During eclipse, CI Aur is redder.
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

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.
Evolution Into Contact of the Low-Mass Close Binary Systems
Authors: Sarna M.J. , Fedorova A.V.
Published: July 2016

We investigated the effect of mass accretion on the secondary components in close binomy systems (Mtotal ≤ 2.5M⊙M2.0 ≤ 0.75M⊙) exchanging mass in the case A.
A Gentle Process for the Formation of Algols
Authors: Tout C. A. , Eggleton P. P.
Published: July 2016

This work is concerned with binary systems that we call ‘moderately close’. These are systems in which the primary (by which we mean the initially more massive star) fills its Roche lobe when it is on the giant branch with a deep convective envelope but before helium ignition (late case B). We find that if the mass ratio q(= M1/M2) < qCrit = 0.7 when the primary fills its Roche lobe positive feedback will lead to a rapid hydrodynamic phase of mass transfer which will probably lead to common envelope evolution and thence to either coalescence or possibly to a close binary in a planetary nebula. Although most Algols have probably filled their Roche lobes before evolving off the main-sequence we find that some could not have and are therefore ‘moderately close’. Since rapid overflow is unlikely to lead to an Algol-like system there must be some way of avoiding it. The most likely possibility is that the primary can lose sufficient mass to reduce q below qcrit before overflow begins. Ordinary mass loss rates are insufficient but evidence that enhanced mass loss does take place is provided by RS CVn systems that have inverted mass ratios but have not yet begun mass transfer. We postulate that the cause of enhanced mass loss lies in the heating of the corona by by magnetic fields maintained by an α-ω dynamo which is enhanced by tidal effects associated with corotation. In order to model the the effects of enhanced mass loss we ignore the details and adopt an empirical approach calibrating a simple formula with the RS CVn system Z Her. Using further empirical relations (deduced from detailed stellar models) that describe the evolution of red giants we have investigated the effect on a large number of systems of various initial mass ratios and periods. These are notable in that some systems can now enter a much gentler Algol-like overflow phase and others are prevented from transferring mass altogether. We have also investigated the effects of enhanced angular momentum loss induced by corotation of the wind in the strong magnetic fields and consider this in relation to observed period changes. We find that a typical ‘moderately close’ Algol-like system evolves through an RS CVn like system and then possibly a symbiotic state before becoming an Algol and then goes on through a red giant-white dwarf state which may become symbiotic before ending up as a double white dwarf system in either a close or wide orbit depending on how much mass is lost before the secondary fills its Roche lobe.
Determining Rotation Rates from Light Curves: RW Mon and RW Tau
Authors: Van Hamme W.
Published: July 2016

We present light curve solutions for the non-synchronously rotating Algols RW Mon and RW Tau, and we illustrate how rotation rates are determined from light curves. We find RW Mon’s primary component to spin at about 5 times the synchronous rate, which confirms the indication of fast rotation from reported emission line activity. RW Tau turns out to be only a mildly rapidly rotating Algol system, and our light curve solutions do not yield any firm value for the rotation rate of the primary component. It is suggested that continued efforts should be made to do good quality line broadening studies in order to find rotation rates for systems with only modest degrees of rapid rotation, and in order to further test photometric rotation rates against those of line broadening studies.
The Importance of Wide-System Studies for Stellar Evolution and Galactic Dynamics
Authors: Dommanget J.
Published: July 2016

Wide pairs and wide multiple systems have been too much neglected during many years by visual double star astronomers with the argument that only close visual pairs (short periods) may lead to mass-determinations in a relatively short time interval. But mass-determination should not be considered as the only interest of double star astronomy, even if it is of a fundamental nature.

Today, it appears that researches on the origin and the evolution of the wide systems are urgently wanted, not only for the understanding of the evolution of the stellar medium, but also for a better knowledge of galactic dynamics. Some examples are given.

Presently, the main task for double star specialists will be an important improvement in double and multiple star census for all kind of systems: close, medium, and wide. The Hipparcos satellite will probably add some important informations in that respect but ground-based observations also remain of the highest importance (radial velocities, photometry, astrometry, etc.).
Nutational Effects in SS 433
Authors: Ruffini Remo , Song Doo Jong
Published: July 2016

The nutation effects of an accreting disk around SS 433 are analyzed within the framework of the fully relativistic model of Fang and Ruffini.
Asteroid Characteristics by Radar
Authors: Goldstein R.M.
Published: July 2016

The techniques of radar offer a potentially powerful tool for the study of planetoids. It is a new approach, having been applied to extraterrestrial targets only recently in the history of astronomical study. Although the Moon was first, Venus has been observed by radar only since 1961. Since that time the techniques and capability of radar have evolved rapidly and many important new facts about Venus have been gathered. Further, the more distant and difficult targets, Mercury and Mars, have also yielded up secrets to radar probing. Finally, during the close approach of June 1968 Icarus itself was observed by radar from two different observatories (Goldstein, 1969; Pettengill et al., 1969). Review articles on radar studies of the planets are given in Shapiro (1968) and Goldstein (1970).
Proper Elements, Families, and Belt Boundaries
Authors: Williams J.G.
Published: July 2016

Families of asteroids were first found by Hirayama (1918, 1923, 1928). More recently Brouwer (1951) and Arnold (1969) have extended greatly the number of families known from the cataloged asteroids. The Palomar-Leiden survey (PLS) (van Houten et al., 1970), which mainly covered very faint, uncataloged objects, found several more families.

Except for the work of Hirayama (1918), which used osculating elements, all of the above studies looked for clusterings of the semimajor axis a, the proper eccentricities é, and proper inclinations í. The calculation of proper elements involves using a theory of secular perturbations to remove the long-period, large-amplitude disturbances of the major planets. The theory used Up to now (Brouwer and van Woerkom, 1950; Brouwer and Clemence, 1961) involved a low-order expansion in the eccentricities and inclinations. There is now a theory available (Williams, 1969) that will accurately handle much higher eccentricities and inclinations than before.
The Distribution of Asteroids in the Direction Perpendicular to the Ecliptic Plane
Authors: Kiang T.
Published: July 2016

For examining the steady-state distribution of asteroids in the direction perpendicular to the ecliptic plane (the z distribution), we shall assume all orbits to be circular. This assumption is incompatible with the north-south asymmetry found by Nairn (1965); but Kresak (1967) has shown that the asymmetry is caused by a combination of cosmic and human factors and is present only among fainter asteroids, B(a, 0)> 16, where the discovery is grossly incomplete. There is another perhaps even more cogent reason for using only the brighter asteroids: The easily understandable practice of confining asteroid hunting close to the ecliptic plane has meant that among the fainter objects, orbits with high inclinations are underrepresented (Kiang, 1966). Actually, in the range 14<B(a, 0)< 15 where, I estimate, the discovery is 95 percent complete, the sample of inclinations may already be somewhat biased in the same sense. One has to balance this risk, however, with the advantage of a much greater data size; and I shall use all the numbered asteroids with B(a, 0)< 15 as given in the 1962 Ephemeris volume (excluding 13 that are regarded as “lost”).
The Relationship of Meteoritic Parent Body Thermal Histories and Electromagnetic Heating by a Pre-Main Sequence T Tauri Sun
Authors: Sonett C.P.
Published: July 2016

Convincing evidence exists that meteoritic matter was reheated shortly after the initial condensation of the solar nebula for those meteorites thought to be derived from parent bodies. This evidence takes the form of cooling rates carefully determined from diffusion studies of the migration rate of Ni across kamacite-taenite boundaries in iron meteorites (Fish, Goles, and Anders, 1960; Goldstein and Ogilvie, 1965; Goldstein and Short, 1967; Wood, 1964). The notion that the irons condensed directly from the solar nebula requires that these measurements and the existence of large Widmanstätten figures be explained as a condensation event. This seems rather unlikely and, in any event, requires a far more complex explanation than heating and melting in a parent body.
Preliminary Results on Formation of Jetstreams by Gravitational Scattering
Authors: Giuli R.T.
Published: July 2016

Alfvén and Arrhenius (1970) have considered the development and stability of jetstreams by collisional interactions among grains; and they propose that in a jetstream environment, grains may collect and adhere to form self-gravitating embryos. Gravitational attraction of smaller particles by these embryos may then lead to a net accretion because high relative approach speeds, which could erode or break up embryos, have been minimized during the formation of the jetstream.
A Study of Asteroid Families and Streams by Computer Techniques
Authors: Lindblad B.A. , Southworth R.B.
Published: July 2016

A study of asteroid orbits is made to determine if there exist groupings of similar orbits in the asteroid population. A computer program based on Southworth's D criterion for similarity in meteor orbits is used. The program successfully sorted out the asteroid families listed by Hirayama, Brouwer, and van Houten et al. A number of new families were detected, several of which appear to be more significant than the minor Brouwer families. Asteroidal streams (jetstreams) are studied and a list of such streams is presented.
Cometary Versus Asteroidal Origin of Chondritic Meteorites
Authors: Wetherill George W.
Published: July 2016

Much of what we know about the early history of the solar system has been learned from the study of meteorites. This results from the fact, demonstrated by isotopic age measurements, that all of the various classes of stone and iron meteorites were formed 4.6 X 109 yr ago within a short period of time, probably less than 100 million yr in duration. This is also the age of Earth and the Moon and may be presumed to be the time of formation of the solid bodies in the solar system. Measurements of the products of the decay of the extinct radioactive isotopes 129Xe and 244Pu show, furthermore, that the formation of these solid bodies occurred within 100 million yr of the time of separation of the solar nebula from interstellar matter. Except for physical fragmentation into smaller bodies, the chemical and mineralogical composition of most meteorites has been essentially unaltered since this time during the formation interval of the solar system.
Is Water Ice the Major Difference Between Comets and Asteroids?
Authors: Delsemme A.H.
Published: July 2016

The nature of the volatile phase in comets has never been established from observations. Although water was likely to be its major constituent, evidence was still circumstantial. It is shown here that water evaporation quantitatively explains not only the brightness of the hydrogen and hydroxyl halos observed by the OAO for the two bright comets of 1970, but also, which is much more convincing, it explains their brightness dependence on the heliocentric distance.
Reasons for not Having an Early Asteroid Mission
Authors: Anders Edward
Published: July 2016

Let me first emphasize the area of agreement with Professor Alfvén. I, too, believe that the asteroids are of very great scientific interest; great enough to justify space missions some day. What we differ on is the timing and target selection for these missions (Alfvén and Arrhenius, 1970, and in this volume). I look upon space missions as a tremendously expensive way of obtaining scientific data, which should not be attempted until all available alternatives are exhausted. Ground-based research on asteroids and meteorites is nowhere near exhaustion; on the contrary, it is moving at an impressive pace. If we maintain this pace for another decade or two, we will not only have answered most of the questions posed for anearlymission, but will be able to come up with a more worthwhile, more informative mission.