bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition and Galactic Confinement of Cosmic Rays
Authors: Shapiro Maurice M. 
Published: March 2016

The ‘Galactic’ cosmic rays impinging on the Earth come from afar over tortuous paths, traveling for millions of years. These particles are the only known samples of matter that reach us from regions of space beyond the solar system. Their chemical and isotopic composition and their energy spectra provide clues to the nature of cosmic-ray sources, the properties of interstellar space, and the dynamics of the Galaxy. Various processes in high-energy astrophysics could be illuminated by a more complete understanding of the arriving cosmic rays, including the electrons and gamma rays.En route, some of theprimordialcosmic-ray nuclei have been transformed by collision with interstellar matter, and the composition is substantially modified by these collisions. A dramatic consequence of the transformations is the presence in the arriving ‘beam’ of considerable fluxes of purely secondary elements (Li, Be, B), i.e., species that are, in all probability, essentially absent at the sources. We shall here discuss mainly the composition of the arriving ‘heavy’ nuclei -those heavier than helium - and what they teach us about thesourcecomposition, the galactic confinement of the particles, their path lengths, and their transit times.
The Lick Observatory Program on Proper Motions of RR Lyrae Stars
Authors: Klemola A. R. 
Published: March 2016

It is the purpose of this note to reveal the nature and progress of a long term astrometric program at the Lick Observatory (see references by S. Vasilevskis in Trans. Int. Astron. Union, XI B, 404, 1962). One of its many goals is the measurement of absolute proper motions of RR Lyrae stars with respect to faint galaxies. The first-epoch photographs, obtained in 1947-54 by Shane and Wirtanen for the sky north of declination – 23°, were supplemented later by plates of poorer quality down to –33° with the 20-in. astrograph. This means that first-epoch plates are now on hand which cover three-fourths of the sky and on which stars of 9-17 mag. may be measured for proper motions. Since these photographs represent the largest and most homogeneous set that will be available in the foreseeable future, we shall try to estimate the number of RR Lyrae stars which may be measured on them.As a guide we take the 1968 edition of the Russian Variable Star Catalogue, which contains a little over 4400 RR Lyrae stars. For the sky north of —33° nearly 2000 of these stars are brighter than average magnitude 17.0, 1000 brighter than 15.0, and about 350 brighter than 12.0. Experience with the Lick program shows that 80% of these stars should be measurable, after account is made for losses due to plate defects, blended images, and other factors.An important limitation to the usefulness of the measured motions is imposed by the size of the mean errors, which amount to 0.”7/century for an epoch difference of 20 yr. This mean error is the same size as the proper motion of a typical RR Lyrae star of 13.0 mag. But for an epoch difference of 50 yr the mean error drops to 0.”3/century, which is comparable to the motion of an RR Lyrae star of 15.0 mag. Useful results for the fainter RR Lyrae stars will not be possible until after a third epoch about the year 2000.
Recent Techniques in Solar Optical Astronomy from Space
Authors: Reeves E.M. 
Published: March 2016

AbstactThe article summarizes some of the recent advances in the techniques of solar space research, particularly over the last 4 years, in an attempt to review the current state of instrument technology. The present state of development in rocket and satellite vehicles for solar observations, far ultraviolet detectors, optical materials, ultraviolet reflection coatings, filters, and photographic film fogging, are among the topics described.
Report on Overlap Methods in Photographic Astrometry
Authors: de Vegt Chr. 
Published: March 2016

The usual procedure for deriving standard coordinates ξ,η from the measured rectangular coordinates x, y of a star is to adopt a suitable model for the relationship between the measured x, y, magnitude m, color index c and the ξ, η. This relationship may, in general, be written asFrom the known standard coordinates ξr, ηr of some reference stars equally distributed over the plate area, the unknown plate constants aijkl, bijkl are found from a least-squares adjustment. After the adjustment the standard coordinates of each field star can be computed. In most cases a statistical criterion for the choice of the proper form of the above relationship between measured and standard coordinates may be useful because the systematic accuracy, obtained from the adjustment, may be seriously affected by the number of unknown parameters included. (Eichhorn et al., 1967). If the same star occurs on two or more plates, i.e. the plates being partly overlapped, one gets the final position by taking the mean of the individual positions on each plate. In this procedure, no direct account is taken of the ‘overlap’ in the equations of condition for the desired plate constants.
The Evolution of Quasi-Stellar Sources and Radio Galaxies
Authors: Ryle M. 
Published: March 2016

There seem to be two promising ways of investigating the evolution of radio sources: (a) the collection of data on a large number of sources so that attempts may be made to arrange them in an evolutionary sequence, (b) the study of a few sources, for which really detailed information is obtainable, to gain insight into the physical mechanisms occurring.It is important to distinguish between the most powerful radio sources, the majority of which appear to have a simple double structure at the resolutions now attainable, and the more complex sources. The structure of the latter suggests that energetic particles have been accelerated in multiple ‘events’, each being of smaller magnitude than the events which give rise to the double sources; the total energy released may, however, be comparable.
Introduction
Authors: Goldberg L. , Švestka Z. 
Published: March 2016

The newly established Inter-Union Commission on Solar-Terrestrial Physics (IUCSTP) has inquired of selected experts about actions useful in the period of the next solar maximum, which need an organization and coordination on international basis. These inquiries have shown that one of the problems, in which a broad international cooperation might lead to substantial improvement of scientific results, is the coordination of ground-base and space-vehicle observations of the Sun and its active phenomena.Therefore, in order to help the IUCSTP in its preparatory work, the chairmen of IAU Commissions 10 (Solar Activity) and 44 (Observations from outside the Atmosphere) agreed to hold a joint meeting of these two Commissions during the IAU Assembly in Prague, on ‘Coordination of solar observations made at ground-base Observatories and with space vehicles’. It was anticipated that other IAU members interested in this problem, particularly members of Commissions 12 and 40, would also take part in the discussion.
The Needs and Requirements from the Standpoint of the Ultraviolet Solar Observations
Authors: Reeves E.M. 
Published: March 2016

Extending from the present to the early part of 1969 there are three Orbiting Solar Observatories to be launched, and these will all be capable of constructing spectroheliograms of the Sun in solar emission lines of the EUV and X-ray region. The recently launched and highly successful OSO-III has obtained EUV and X-ray spectra with high-time resolution, but without spatial resolution on the solar disk. The later OSO satellites will provide spatial resolution of 1′ of arc to 30″ of arc, and will provide the basis for the extension to even higher spatial resolution in the future.The comparatively short periods covered by these satellites, coupled with a real probability of only partial success, make it particularly important to obtain the fullest possible use of the data by implementing a complementary and simultaneous series of ground-based observations.
Galaxies and Their Nuclei
Authors: Ambartsumian V. A. 
Published: March 2016

Our Extraordinary General Assembly is devoted to the memory of one of the greatest men of science to the genial Polish astronomer - Nicolaus Copernicus. The main service of Copernicus which has made his name immortal was in finding the correct interpretation of the planetary motions we observe. Instead of geocentric notions, which proved unable to explain the accumulated bulk of empirical data on the apparent motions of planets he has put forward and advocated the notion of a solar system thus presenting the true picture of the part of the Universe we live in. The scientific revolution started by him was continued by Galileo and Kepler and was crowned with the great theoretical generalizations of Newton. As a result a foundation has been created for the most exact theories of motions in the solar system which were developed during the next centuries. These theories in their modern form give also the possibility to solve all the problems concerning the orbital motions of spaceships.At this stage we can not yet boast that in the study of nuclei of galaxies and their activity we have reached the level which existed in planetary astronomy even before the works of Newton. Only 15 years elapsed from the moment when the idea of activity of nuclei of galaxies was clearly formulated (Ambartsumian, 1958). During these years discoveries of the greatest importance have been made. New unexpected discoveries occur almost each year. These discoveries influence decisively our notions on the diversity of objects and phenomena in the distant space, but they are still insufficient for the construction of adequate theories. In order to penetrate into the very nature of nuclear phenomena we require new observations, new measurements and new data. And if some optimists imagine that the time has already ripen to build a general theory of these phenomena, the more cautious astronomers would like to consider a more or less satisfactory systematization of observational data concerning the activity of nuclei and the understanding of external physical processes accompanying it as a tremendous success.
Pro and Contra Changes in the Conventional Values of Precession
Authors: Fricke W. 
Published: March 2016

AbstractFrom an evalution of the arguments pro and contra changes in the precessional constants it is concluded that corrections should be made simultaneously with changes in the values of planetary masses at the time when the new fundamental reference system, the FK5, is introduced into the ephemerides. In this case the location and motion of the equinox would be corrected at the same time. An IAU decision on changes in the constants should be made in 1976. Since the completion of the FK5 may be expected around 1980, the introduction into the ephemerides appears practicable in 1984.
Gould’s Belt
Authors: Lindblad P. O. 
Published: March 2016

The zone of bright stars inclined 20° to the galactic plane, pointed out by John Herschel (1847) and by Gould (1874,1879), is generally referred to as Gould’s Belt. This General Assembly is well timed. With the splendour of the centre of the Milky Way in the zenith in the early hours of the night anyone who comes out of the city-lights of Sydney can try to convince himself of the reality of this phenomenon.Shapley and Cannon (1922, 1924) showed that the concentration towards Gould’s Belt is very pronounced for the brighter B. stars, while the fainter ones are highly concentrated towards the galactic plane. Their results indicated the radius of this local system to be of the order of 500 pc. The motions of the B. stars brighter than a magnitude of about 5m.5 are characterized by the K-effect, which thus seems to be a property of this local Gould Belt system.
Space Distribution and Motion of the Local HI Gas
Authors: Weaver H. 
Published: March 2016

In a Joint Discussion devoted to the ages and kinematics of the local stars, inclusion of a paper on the local gas may seem anomalous. There is, however, strong justification for considering such a topic. Newly formed stars retain many properties of the gas from which they originated. To understand the spatial and kinematic properties of local young stars, we must understand the spatial distribution and the kinematics of the local gas from which they were formed.A cloud within the interstellar gas can collapse gravitationally if its mass, density, and temperature satisfy the Jeans Criterion. Collapse is favored by low temperature and high density.Various investigators have pointed out that in the Lin Spiral Density Wave Theory a shock must occur on the inner edge of a spiral arm. Such a shock compresses the gas and hence promotes cloud formation with subsequent gravitational collapse to form stars. Shu and several collaborators have shown that such a shock is very effective in triggering cloud formation in a two-phase interstellar medium of the type discussed by Field et al. (1969), and it is widely believed that this is the principal step in the process of forming stars.
[no title]
Authors: McCarthy Martin F. 
Published: March 2016

After urging you all to briefness, I should set a good example. I “welcome you all: participating colleagues and all IAU members and guests, especially those from our host commissions 25, 33 and 45. I thank you all: the contributors to today’s events, to the members of the Organizing Committee, to the Presidents of the sponsoring Commissions, IAU officials and all those who are not here today but have helped to make the arrangements for today’s discussion.To assist with the direction of our work I have asked Prof. K. Aa Strand, Prof. T. Elvius and Prof. B. Bok to preside over Parts One, Two and Three. Questions and comments may be made to the invited speakers and to the discussion contributors at the end of each Part of our program.
The Stellar Distribution above the Galactic Plane: An Introduction
Authors: King Ivan R. 
Published: March 2016

This paper will truly be an introduction — a presentation and a discussion of the basic problems, to set the stage for detailed research results that will be reported by others.The problem of star distribution perpendicular to the galactic plane has one central theme, which can be played in two modes. The theme is the drop-off of star-density with z, and the two modes are the general density profile and the stratification of populations. (This last phrase is a convenient one, but I should warn against taking it too literally. By “stratification” I mean a gradual change, rather than a sharp separation; and I want to emphasize even more strongly that the word “population” should be used in a general and abstract sense, rather than as a sharp separation into two, or five, or any other discrete number of components.)
Search for Large Radial Velocities in Direction of NGP Using the Fehrenbach Techniques
Authors: Florsch Alphonse 
Published: March 2016

The Observatory of Strasbourg will participate in the future in the general radial velocity survey which is in hand at the Observatories of Haute-Provence and of Marseille with FEHRENBACH’s Objective-prism astrograph. A programme of this type, providing a large number of data, is particularly suitable at the place where the “Data Center” is growing up.A radial velocity survey is a vast programme which needs many years to be fulfilled. It is natural that one starts with the most interesting areas in the sky, one of them being the area near NGP. In 1976 twenty fields were covered, each by one plate, in that direction. The whole programme covers 70 overlapping fields in an area of 100 square degrees centered at NGP. The limiting magnitude shall be almost the 12th.
Spectral Classification of B and A Stars from the Line Features of S2/68 Spectra
Authors: Cucchiaro A. , Jaschek M. , Jaschek C. 
Published: March 2016

The experiment S2/68 has supplied a large number of ear type spectra in the wavelength region 1350–2730 A. The resolution is 37 A, which is about equivalent to a reciprocal dispersion of 1850 A/mm. We had at our disposal about one thousand spectra of stars brighter than 6m5.The availability of such material has lead us to establish a spectral classification system based only upon features visible in the spectrum. A second step was to compare this system to the MK classifications.It turned out to be easy to establish a temperature sequence based upon convenient intensity ratios of line features and somewhat more difficult to establish luminosity criteria. Among the B type stars it is possible to distinguish main sequence objects, supergiants and intermediate objects.
The Uniqueness of the Geographic South Pole for the Observations of Large Scale Velocity Fields on the Sun: Some Experiences from a 120 Hours Continuous H-Alpha Patrol during January 1979
Authors: Kusoffsky U. , Pomerantz M. A. 
Published: March 2016

Continuous solar observations over extended periods of time with the sun at constant altitude have heretofore been unobtainable. A solar observatory at the geographic South Pole will provide continuous homogenous observations of various solar features during the austral summer months. An optical site testing campaign during January 1979 showed seeing conditions at the site to be even better than expected. During the 1979-80 austral summer solar global oscillations will be studied with the Nice sodium cell spectrophotometer. Lifetime studies of the chromospheric network will be conducted with a 30-cm heliostat in combination with a 20-cm f/100 objective lens to provide a 20-cm solar image for monochromatic filters during the following year.A report published a decade ago by the U. S. National Academy of Sciences (1970) devoted one chapter to a discussion of the potential advantages of conducting certain types of astronomical observations at the geographic South Pole. One unique feature of this site is that it affords the opportunity for obtaining continuous homogenous observations with a single instrumental system over extended periods of time. Furthermore, special benefits for solar research stem from the constant angular level of the sun in the sky and the uniform local geography of the high altitude polar plateau (2912 meters, mean atmospheric pressure 680 mb corresponding to roughly 3300 meters at midlatitude).
Infrared Emission from Spiral Galaxy Nuclei
Authors: Wynn-Williams C. G. 
Published: March 2016

At the present time we do not know with any certainty what the infrared properties of “normal” galaxies are, although we do know that substantial broad-band emission at 10μm is fairly common in spiral galaxies; Rieke and Lebofsky (1978), for example, were able to detect the nuclei of 16 out of 39 bright spiral galaxies above a level of about 50 mJy. Only one of these, NGC 1068, is a Seyfert Galaxy.With the exception of M31, whose 10μm emission can be accounted for entirely by stellar photospheric emission, all the spiral galaxies detected in Rieke and Lebofsky’s survey show strong emission from heated dust grains. Airborne observations at longer wavelengths (e.g., Telesco and Harper 1980) of a few of these galaxies show a peak in the energy distribution at around 80μm, corresponding to dust temperatures of order 30-60K, while spatial scans, and multi-aperture photometry at 10μm (Rieke 1976; Becklin, Fomalont, and Neugebauer 1973; Becklin et al. 1980) indicate a physical size for the emitting region of a few hundred parsecs diameter.
Abundances in Diffuse Interstellar Clouds
Authors: Jura M. 
Published: March 2016

Interstellar clouds are concentrations of cold (T ≲ 100 K) neutral gas (cf. Spitzer 1978) which are immersed within an intercloud medium. It is worthwhile to distinguish between diffuse clouds (roughly those with E[B-V] ≳ 0.5) and dark clouds (those with E[B-V] ≳ 0.5). This distinction is useful in the sense that diffuse clouds are relatively warm (T ∼ 100 K), they are composed mostly of atomic species except for hydrogen which can be appreciably molecular, and they are dynamically controlled by their interaction with the intercloud medium. Dark clouds are relatively cold (T ∼ 10 K), they contain a rich variety of molecules, and self-gravity is important in their evolution. Because the interstellar extinction is a rapid function of wavelength, most ultraviolet observations have been of diffuse clouds. The IUE satellite is sufficiently powerful that observations of some dark clouds are possible, and an important area of future research will be to delineate more quantitatively the similarities and differences between diffuse clouds and dark clouds.With ultraviolet observations, considerable progress has been made in understanding the physical characteristics of clouds including determinations of their densities, temperatures, chemical compositions and dynamics (cf. Spitzer and Jenkins 1976). Because particular progress has been made on understanding the abundances within diffuse clouds and because of the limitations of space, we restrict this review to a discussion of abundances within diffuse clouds. These abundance measurements provide a set of fundamental astrophysical data.
Recent Theoretical Results for δ Scuti and Dwarf Cepheid Variables
Authors: Percy John R. 
Published: March 2016

Recent evidence suggests that δ Set stars and most dwarf Cepheids are population I objects of normal mass. The remaining dwarf Cepheids, including CY Aqr, DY Peg, SX Phe and GD 428, have low masses, are metal-deficient, and are in a presently undetermined stage of evolution (Breger 1979, McNamara and Feltz 1978, but see also Simon 1979).Many δ Set and dwarf Cepheid variables are multiperiodic and, in principle, multiple periods can be used to infer physical properties of these stars. The component periods must be determined accurately and reliably, and several workers (Breger, Fitch, Kurtz, Pelt, Percy, Shob-brook, Stellingwerf, Stobie and Warman) are active in developing and applying new methods of period analysis; see Wizinowich and Percy (1979) for a representative example.One result of these analyses is the discovery that in some stars, modes may vary in amplitude or appear or disappear completely within a few days (Stobie and Shobbrook 1976). Methods of period analysis must allow for this possibility if they are to be accurate and reliable.
Observations of Classical Cepheids
Authors: Madore Barry F. 
Published: March 2016

Calibration of the Period-Luminosity relation for Classical Cepheids is still far from settled: the debate continues as to whether there is a unique relation from galaxy to galaxy and what the precise form is in any one system. In the Milky Way we suffer from poor sample size; in the Magellanic Clouds it is still a matter of low accuracy in the observations. Work is in progress at several observatories to alleviate both of these problems through studying not only galactic Cepheids but also those in the LMC, SMC, M33 and NGC 300.Arellano & Percy (CTI0/DD0) have begun a photoelectric monitoring of the apparently brightest F & G supergiants in the Milky Way. The aim is to detect near-by very-low-amplitude Cepheids which are binaries or are intrinsically low amplitude variables. This should provide a better qualitative hold on the sense of the amplitude dependence on effective temperature, as well as the true fequency of the cepheid phenomenon.