bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Astronomy and Cosmology of Copernicus
Authors: Gingerich Owen 
Published: March 2016

It was close to the northernmost coast of Europe, in the city of Toruń, that the King of Poland and the Teutonic Knights signed and sealed the peace of 1466, which made West Prussia part of Polish territory. And it was in that city, just seven years later and precisely 500 years ago, in 1473, that Nicholas Copernicus was born. We know relatively few biographical facts about Copernicus and virtually nothing of his childhood. He grew up far from the centers of Renaissance innovation, in a world still largely dominated by medieval patterns of thought. But Copernicus and his contemporaries lived in an age of exploration and of change, and in their lifetimes they put together a renewed picture of astronomy and geography, of mathematics and perspective, of anatomy, and of theology.When Copernicus was ten years old, his father died, but fortunately his maternal uncle stepped into the breach. Uncle Lucas Watzenrode was then pursuing a successful career in ecclesiastical politics and in 1489 he became Bishop of Varmia. Thus Uncle Lucas could easily send Copernicus and his younger brother to the old and distinguished University of Krakow. The Collegium Maius was then richly and unusually endowed with specialists in mathematics and astronomy; Hartmann Schedel, in his Nuremberg Chronicle of 1493, remarked that “Next to St. Anne’s church stands a university, which boasts many eminent and learned men, and where numerous arts are taught; the study of astronomy stands highest there. In all Germany there is no university more renowned in this, as I know from many reports.” At the university the young Nicholas embraced the study of astronomy with a passion found only in the most exceptional of undergraduates. There he learned about the works of Sacrobosco, Regiomontanus, Ptolemy, and Euclid.
X-Ray Sources in Close Binary Systems
Authors: Rees M. J. 
Published: March 2016

The discovery by Giacconi and his colleagues of variable X-ray sources in close binary systems certainly ranks as one of the highlights of astronomical research during the last 3 years. These remarkable objects have already been extensively studied, by optical and radio observations as well as in the X-ray band; and they seem likely to prove as significant and far-reaching in their implications as pulsars.The ‘Third Uhuru Catalogue’ (Giacconi et al., 1973a) contains about 160 sources, of which about 100 lie in our Galaxy. Their distribution over the sky (together with other arguments) suggests that these sources have luminosities of the general order 1036–1038 erg s−1, and that their typical distances are ˜ 10kpc. These galactic sources generally display rapid variability. Little else is known about most of them, but they are probably of the same general class as systems such as Her X1, Cen X3, Cyg X1 and Cyg X3. These sources have been investigated in detail, and in all cases one infers a system where the X-ray source is orbiting around a relatively ordinary star. Six sources have been optically identified, and there are some others whose binary nature is established by the occurrence of an X-ray eclipse. Orbital periods range from 4.8 h (Cyg X3) up to ˜ 10 days.
The Correlation Between Kinematical Properties and Ages of Stellar Populations
Authors: Einasto J. 
Published: March 2016

The spatial and kinematical properties of galactic populations are very conservative for time changes. Therefore the study of these properties gives us certain information on the past dynamical evolution of the Galaxy, in particular on the evolution of star generating medium (interstellar gas, as generally accepted). The detailed study of spatial structure of stellar populations in our Galaxy is possible in exceptional cases only. But the study of kinematical properties is possible practically for all populations, which makes these studies very useful for cosmogonic purpose.In order to obtain adequate quantitative information for the study of dynamical history of the Galaxy the statistical data on stellar velocities are to satisfy the following requirements: populations under study must be physically homogeneous; statistical samples of stars must be free from selection effects, especially from velocity selection; information on r.m.s. errors of observed quantities must be known in order to correct the results for accidental observational errors; the data for the determination of the age of the sample must be available.
Solar Neighbourhood as the Local Macroscopic Volume Element Within the Galaxy
Authors: Agekjan T. A. , Ogorodnikov K. F. 
Published: March 2016

The notion of the local Macroscopic Volume Element (MVE) is introduced in order to facilitate the application of hydro-dynamical methods of treating internal motions in stellar systems and in particular in our Galaxy. The MVE must characterize the properties of the stellar system in a given point within the system. Hence the diameter of the MVE must be taken as small as possible; it must, however, contain a sufficiently large number of stars in order that the laws of statistics might be applied. The greater is the local star density the smaller can be made the size of the MVE.Modern catalogues of nearby stars by Gliese (1969) and Woolley et al. (1970) afford a good collection of data for a determination of local characteristics of the Galaxy in the immediate neighbourhood of the Sun. In the first section we discuss such characteristics as the local stellar density, the local luminosity function and the influence of observational selection upon them. In the second section we consider the local solar motion and the effect of the asymmetry of stellar motions. The responsibility for the content of paragraph 1 lies primarily upon T. A. Agekjan while that for paragraph 2 upon K. F. Ogorodnikov. We both are indebted to G. V. Ishkhanov and to L. V. Chuvicova for substantial help in numerical computations.
Coordinated Campaign to Observe X-Ray Binaries
Authors: Kondo Yoji 
Published: March 2016

The coordinated campaign to observe x-ray binaries sponsored by the IAU Commission 42 (Close Binary Stars) and Commission 44 (Astronomical Observations from Outside the Terrestrial Atmosphere) was initiated in January 1974 with Y. Kondo as its coordinator.The main objectives of the campaign have been: (a) dissemination of information on satellite x-ray experiments and ground-based observing programs; (b) transmission of suggestions and recommendations from campaign participants; (c) designation of campaign dates for observation of specific objects. These functions have, in part, been performed through Campaign Circulars and Special Bulletins; the most recent, Circular No. 23, was issued a few weeks ago.
The Space Density of M Dwarfs - An Observational Program
Authors: Pesch Peter 
Published: March 2016

In spite of extensive proper motion surveys, there remains some uncertainty about the space density and the kinematics of late-type dwarf stars. This uncertainty is primarily due to the unknown kinematic bias introduced by the proper motion discovery technique.A spectrographic search, especially one using an objective prism on a Schmidt telescope, can identify significant numbers of intrinsically (and actually) faint stars, free from any kinematic bias. To find faint and cool stars, one chooses an objective prism with low dispersion and emulsions sensitive to the red and near photographic infrared. At low dispersions, in this wavelength region, there are no reliable luminosity criteria. Thus Sanduleak conducted his survey in the direction of the north galactic pole, with the expectation that very few remote giants would contaminate his results. A catalog of 273 probable dwarf stars of type M3 and later (Sanduleak, N. 1976, A.J., 81, 350) based on his objective prism survey in the direction of the north galactic pole is now available. Thanks to W.J. Luyten (1976, Proper Motion Survey with the Forty-Eight Inch Schmidt Telescope XLVI (Univ. Minnesota, Minneapolis)) proper motions have been measured for all of these stars.
The Frequency of Faint M Giant Stars at High Galactic Latitudes
Authors: Sanduleak N. 
Published: March 2016

Based on the observations of M giant stars in the north galactic polar objective-prism survey of Upgren (1960) and the data summarized by Blanco (1965) the overall space density of all M-type giants as a function of distance from the galactic plane at the position of the sun can be approximated by,where z is in kpc and ρ(z) is the number of stars per 106 pc3. This relationship is derived from the observed fall-off in space densities up to a distance of about 2 kpc.The question arises as to the validity of extrapolation equation (1) to larger z distances so as to predict the number of faint M giants expected per unit area near the galactic poles. Adopting for the M giants a mean visual absolute magnitude of −1.0 (Blanco 1965), one finds that equation (1) predicts that less than one giant fainter than V~12 should be expected in a region of 200 square degrees. This expectation formed the hypothesis of a thesis study (Sanduleak 1965) in which it was assumed that the very faint M stars detected in a deep, infrared objective-prism survey at the NGP were main-sequence stars, since this could not be ascertained spectroscopically on the very low-dispersion plates used.
Boundary Conditions with Mass-Loss: General Considerations
Authors: Thomas Richard N. 
Published: March 2016

I begin by stating very explicitly and unambiguously that I completely disagree with any idea that a stellar atmosphere can be in any sense a boundary of the star, or that the atmosphere sets boundary conditions on stellar structure. Such an idea is what underlies all the single-layer, LTE atmospheric models, which misdirected atmospheric studies for so many years by introducing a false separation between “normal” and “extended” atmospheric phenomena. On the contrary, I assert that a more correct physical picture for the atmosphere than as a boundary comes from the characterization of star and atmosphere as:(1) The STAR is: a concentration of matter and energy, C (M, E), in its parental environment, the interstellar medium (ISM); with boundary conditions on stellar structure being set by the way one models (a) storage modes for matter and energy in the star and ISM, and (b) energy generation in the star.
Mass Loss in Stars of Moderate Mass by Stellar Winds and Effects on the Evolution
Authors: de Loore C. 
Published: March 2016

Some 30 years ago it became clear that the solar corona is a plasma with a temperature of the order of 106K. As the underlying layers have only temperatures of 5000 K a mechanism had to be discovered, capable to explain this high temperature. A solution to the problem was found when it was realized that mechanical energy losses, by shock dissipation of wave energy can heat up a plasma to such high temperatures. This mechanical energy is formed in the deeper layers of the atmosphere and transported outwards. Dissipation becomes significant in regions where the density is sufficiently low.Wave propagation in a compressible medium in the presence of gravity and magnetic fields has been treated as a general problem, among others by Ferraro and Plumpton [1958). Three basic parameters are present: compressibility of the medium, gravity and magnetic field.
Stellar Evolution and Close Binaries
Authors: Paczynski B. 
Published: March 2016

A general scheme of evolution of close binaries is outlined. Many types of observed systems are classified according to their evolutionary status. Present theory can account reasonably well for the mass transfer between the two components. There is no satisfactory theory of mass and angular momentum loss from binary (as well as single) stars. Most close binaries sooner or later should develop extended common envelopes. A loss of a common envelope may remove a large fraction of mass and most of angular momentum from a binary, and leave as a remnant a very short period and highly evolved system. Binary nuclei of planetary nebulae, cataclysmic variables and some X-ray binaries are produced this way.I shall present here a picture of the evolution of close binary systems (CBS) as it is understood now. This is not intended to be a review, and no attempt has been made to make the list of references complete. Usually I shall refer the first paper on a given subject and/or one of the recent ones, where a large number of other references can be found. There are many reviews and proceedings of various symposia that deal with close binaries. Here are some: Annual Review of Astronomy and Astrophysics (9, 183,14, 119,15, 127,16, 171, 241), IAU Symposia No. 73, 83, 88, IAU Colloquia No. 42, 46, 53. I shall try to emphasize what is known and what is not known, and how various observed systems fit into the theoretical evolutionary scheme. Because of my background I shall give more references to theoretical papers. Nevertheless, I am convinced that it was the theory of close binaries that was guided in its development by the observations, not other way around. In fact the theory predicted very few new phenomena and very few new types of binaries. But it managed to account, at least qualitatively, for the major evolutionary processes, and made it possible to arrange the observed systems into the evolutionary sequences.
Radio Continuum Observations of the Nucleus of our Galaxy and Other Normal Galaxies
Authors: Ekers R. D. 
Published: March 2016

The radio properties of the nuclei of normal galaxies have been reviewed by Ekers (1974, 1978a, 1978b) and of the Galactic Centre by Oort (1977). In this report I will concentrate on material available since then. The following paper by Van der Hulst extends this review with more information on the structure of the central sources in normal galaxies.No complete high resolution maps of Sgr A have been made since the “WORST” map (Ekers et al. 1975) so I will use it as a reference for the new information which is available. At the lower frequency of 327 MHz there have been a series of occultation measurements by Gopal-Krishna and Swarup (1976). These again show the separation into two components; a nonthermal Sgr A East and a thermal Sgr A West. In addition they show some spatial variation in the nonthermal spectral index and also suggest that the nonthermal source extends over the entire region of Sgr A. From observations using the RATAN telescope Parijskij (private communication) also suggests that the Sgr A East component might just be a peak on a more symmetrical nonthermal source which is centred on Sgr A West. RATAN observations are in progress in the wavelength range from 2-6 cm and these confirm the thermal nature of Sgr A West. As the VLA elements come into operation along more than one arm of the Y it becomes possible to use it to map Sgr A. 5 and 15 GHz maps (Brown, Lo and Johnston 1978 and private communication) with a resolution of a few seconds of arc resolve the Sgr A West source into a number of components with an overall size of ˜l’ × 30’ elongated along the galactic plane and centred on the Sgr A West point source (Balick and Brown 1974). The VLA maps of Sgr A West agree well with the inner contours of the WORST map and this distribution of emission is similar to that seen in the 53μ map (Harvey, Cambell and Hofmann’ 1976). Such an association is common in HII regions and is consistent with the thermal nature of Sgr A West.
IUE Observations of Novae
Authors: Sparks Warren M. , Wu Chi-Chao , Holm Albert V. , Schiffer Francis H. 
Published: March 2016

In addition to offering observing time on a regular schedule, the International Ultraviolet Explorer (IUE) satellite is also being used to observe “targets of opportunity.” Novae represent one of the most exciting targets of opportunity and also one of the most difficult because of their rapid time behavior. During the first year of operation of IUE we were extremely fortunate to have three bright novae outbursts occur: Nova Cygni 1978, WZ Sagittae, and U Scorpii.Nova Cyg 1978, a fast nova, reached a maximum apparent visual magnitude of 6.2 on September 12, 1978 (Slovak and Vogt 1979). Figure 1 shows the relative flux of Nova Cyg 1978 in the long ultraviolet wavelength range (1900-3200Å) at several different times. One day after maximum (Sept. 13), the nova is still in its absorption line phase. At this point it looks like a supergiant F star with mostly Fell absorption lines (also see Cassatella et al. 1979). Later spectra show the emergence of emission lines, which is the characteristic behavior of novae in the visual. Magnesium II at 2800Å is the strongest emission line in this part of the spectrum for at least a month after outburst. The last spectrum (Nov. 1) shows mainly semi-forbidden lines of carbon, nitrogen, and oxygen. It should also be noted that the slope of the continuum flattens as the nova evolves.
Theoretical Review of Secular Instabilities in the Sun
Authors: Gabriel M. 
Published: March 2016

In this review we discuss the problems raised by the discovery that the sun was, in the past, unstable towards non-radial oscillations.In 1972, Fowler (1972), in an attempt to explain the low-neutrino flux measured in Davis’ experiment (now 1.6 snu, while the standard solar model predicts 4.4 snu) suggested that the sun could have undergone, some 10 years ago, a change in structure because of sudden mixing of the inner core. During the same year Dilke and Gough (1972) suggested the sun is unstable to low-order gravity modes (g+ modes) of non-radial oscillation and that the mixing is triggered when the amplitude of the oscillation becomes large enough.
Shell Flashes
Authors: Sackmann I.-Juliana 
Published: March 2016

Shell flashes will be discussed here with regard to three different stages of evolution: 1. normal stars, 2. white dwarfs accreting H-rich matter and 3. neutron stars accreting matter.A shell flash Is a thermal instability, a nuclear run-away process, occurring inanynuclear burning shell, as long as It is sufficientlythinin geometrical extent and sufficiently thick for a high enough heat capacity. (in contrast to the off-center helium shell flash, another kind of shell flash which occurs for degenerate matter, the shell flash discussed here does take place for an Ideal gas including radiation pressure and does not require degeneracy.) The first shell flash discovered was theheliumshell flash, about 15 years ago, by Schwarzschild and Härm (1965); Hayashi, Hoshi, and Suglmoto (1965); and Weigert (1965, 1966).
The Large-Scale Structure of the Corona
Authors: Zirker Jack B. 
Published: March 2016

The solar corona serves as a prototype of the outer atmospheres of all cool stars. Because of its nearness we can study this prototype in more detail than any other example. Considerable progress has been made recently in understanding how the large scale structure of the solar corona controls the genesis of the solar wind and the distribution of slow and fast wind streams throughout the three-dimensional space surrounding the sun. In this review we will discuss some of the progress made in this field during the last few years. We will emphasize the observational data and the inferences that can be made more or less directly from them. T. Holzer will discuss the theoretical aspects of stellar wind acceleration in another paper in this symposium.The large scale structures of the solar corona consist essentially of three kinds: streamers, active regions and coronal holes. Figure 1 is a familiar photograph of the solar corona, obtained in white light at the total eclipse of 30 June 1973 by the High Altitude Observatory. The streamers are the petal-like structures extending out from the black lunar limb. They taper to narrow radial spikes that have been traced out as far as 10-12 solar radii (Keller, 1979). Daily measurements of the white light corona at the Mauna Loa Observatory (Hundhausen et al. 1979) and the Pic-du-Midi Observatory (Dollfus et al., 1977) since 1965 show that the streamers are fan-shaped structures that may extend 120° in solar longitude. We see them in various perspectives at the solar limb.
High Energy Astrophysics and Cosmology
Authors: Woltjer L. 
Published: March 2016

AbstractA brief review is given of cosmological tests based on quasars, of source evolution and of the X-ray background. The cosmological tests are still inconclusive because of the limited material available and the possibility of serious selection effects. Quasars and other extra-galactic sources account for most or all of the background in the 1-10 kev range and very possibly also at higher X- and γ-ray energies.
A Review of Recent Ultraviolet Observations of Close Binaries from Space
Authors: Kondo Yoji 
Published: March 2016

The reason for presenting this review at this Joint Meeting, in spite of the fact that there was, a few days ago, a special Joint Discussion on recent UV observations is partially that somehow the general subject of close binaries was overlooked at the Joint Discussion, although unique close binaries, such as cataclysmic binaries and X-ray binaries, were included. There exist a large number of vigorous research projects being carried out with UV telescopes in the field of close binaries. I shall concentrate on IUE results, although other satellite and balloon-borne telescopes have continued to produce interesting UV observations of close binaries.There are a number of active IUE programs on this theme. In the time allocated to this review I shall only be able to present highlights of selected programs in the hope of giving a glimpse of what is going on. The programs on close binaries from the first year of IUE operations include those by P. Conti, M. Hack, J.B. Hutchings, R.H. Koch, Y. Kondo and G.E. McCluskey, M. Plavec, and J. Sahade. In the second year, additional astronomers are also observing close binaries with the IUE.
The Origin and Early History of the Sun and the Planetary System in the Context of Stellar Evolution
Authors: Herbig G. H. 
Published: March 2016

AbstractA plausible scenario for the early history of the sun can be constructed by combining the results of stellar astronomy with lunar and meteoritic chronologies. The meteorites apparently contain material exposed to two nucleosynthetic events, one about 108 yr and another a few 106 yr before solidification. Following II. Reeves, these are associated with supernovae occurring in star clusters in molecular clouds that formed during passage through successive galactic arm shocks. The Orion Trapezium Cluster may be a modern example; its density is such that encounters between members would have been close enough and frequent enough to have had major effects upon their circumstellar ‘solar nebulae,’ as would recurrent FU Ori-like eruptions of the stars themselves. The lunar bombardment continued for 7 × 108 yr following formation of our sun. If this represented disk cleanup, disks must persist for that long, and hence circumstellar activity may still be in progress around some young stars in the solar vicinity. The observed time decay of axial rotation and surface activity in solar-type stars can be extended backwards, and indicates that the ultraviolet radiation of the young sun would have had major photochemical consequences upon the primitive earth.
Eddington and Mass Loss
Authors: Tayler R. J. 
Published: March 2016

AbstractThis joint discussion is dedicated to the memory of Sir Arthur Eddington who was born 100 years ago. He laid the foundation of much work on stellar evolution, which was summed up in his book The Internal Constitution of the Stars (ICS) which appeared in 1926. Although he did no substantial work on mass loss from stars, the possibility of mass loss is mentioned in several places in ICS and I shall mention these and other aspects of Eddington’s work which are relevant to our present interest.