bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Report on Phase 2 of the Fifth International Radiocarbon Intercomparison (VIRI)
Authors: Scott E Marian , Cook Gordon T , Naysmith Philip 
Published: July 2016

The Fifth International Radiocarbon Intercomparison (VIRI) continues the tradition of the TIRI (third) and FIRI (fourth) (Scott 2003) intercomparisons and operates in addition to any within-laboratory quality assurance measures as an independent check on laboratory procedures. VIRI is a phased intercomparison; results for the first phase, which employed grain samples, were reported in Scott et al. (2007). The second phase, involving bone samples, is reported here. The third and final phase, which includes samples of peat, wood, and shell, has also been completed and a companion paper appears in these proceedings.Five bone samples were made available and included Sample E: mammoth bone (>5 half-lives); Sample F: horse bone (from Siberia, excavated in 2001; and Samples H and I: whale bones (approximately 2 half-lives). Sample G (human bone) was accessible only to accelerator mass spectrometry (AMS) laboratories because of the limited amount of sample available. More than 40 laboratories participated in Phase 2 and consensus values for the ages were as follows: Sample E = 39,305 14C yr BP (standard deviation [1 σ = 121 yr); Sample F = 2513 yr BP (1 σ = 5 yr); Sample G = 969 yr BP (1 σ = 5 yr); Sample H = 9528 yr BP (1 σ = 7 yr); and Sample I = 8331 yr BP (1 σ = 6 yr). Sample G had previously been dated by 4 laboratories and a weighted mean of 934 ± 12 yr BP had been quoted. Sample I had previously been dated at 8335 ± 25 yr BP and Sample H had been dated at 9565 ± 130 yr BP. Results for Sample H and Sample I are in good agreement with the previous results; Sample G results, however, give a value that is significantly older than the previously reported results.
Iron-Manganese System for Preparation of Radiocarbon Ams Targets: Characterization of Procedural Chemical-Isotopic Blanks and Fractionation
Authors: Verkouteren R. Michael , Klinedinst Donna B. , Currie Lloyd A. 
Published: July 2016

We report a practical system to mass-produce accelerator mass spectrometry (AMS) targets with 10–100 μg carbon samples. Carbon dioxide is reduced quantitatively to graphite on iron fibersviamanganese metal, and the Fe-C fibers are melted into a bead suitable for AMS. Pretreatment, reduction and melting processes occur in sealed quartz tubes, allowing parallel processing for otherwise time-intensive procedures.Chemical and isotopic (13C,14C) blanks, target yields and isotopic fractionation were investigated with respect to levels of sample size, amounts of Fe and Mn, pretreatment and reduction time, and hydrogen pressure. With 7-day pretreatments, carbon blanks exhibited a lognormal mass distribution of 1.44 μg (central mean) with a dispersion of 0.50 μg (standard deviation). Reductions of 10 μg carbon onto targets were complete in 3–6 h with all targets, after correction for the blank, reflecting the13C signature of the starting material. The 100 μg carbon samples required at least 15 h for reduction; shorter durations resulted in isotopic fractionation as a function of chemical yield. The trend in the13C data suggested the presence of kinetic isotope effects during the reduction. The observed CO2-graphite13C fractionation factor was 3–4% smaller than the equilibrium value in the simple Rayleigh model. The presence of hydrogen promoted methane formation in yields up to 25%.Fe-C beaded targets were made from NIST Standard Reference Materials and compared with graphitic standards. Although the12C ion currents from the beads were one to two orders of magnitude lower than currents from the graphite, measurements of the beaded standards were reproducible and internally consistent. Measurement reproducibility was limited mainly by Poisson counting statistics and blank variability, translating to14C uncertainties of 5–1% for 10–100 μg carbon samples, respectively. A bias of 5–7% (relative) was observed between the beaded and graphitic targets, possibly due to variations in sputtering fractionation dependent on sample size, chemical form and beam geometry.
14C Profiles in the Norwegian and Greenland Seas by Conventional and AMS Measurements
Authors: Nydal Reidar , Gislefoss Jorunn , Skjelvan Ingunn , Skogseth Fred , Jull A. J. T. , Donahue D. J. 
Published: July 2016

CO2 in the atmosphere is an important climate gas because of its absorption of infrared radiation. More knowledge about CO2 uptake in the ocean is of critical significance in predicting future climate development. For a period of approximately 30 years, radioactive carbon from nuclear tests has been a very useful tracer in CO2 exchange studies. Up to now, the measurements have been based mainly on the conventional counting technique with large CO2 samples (ca. 5 liters). Accelerator mass spectrometry (AMS) with small CO2 samples (1–2 ml) has made sampling much easier, and has especially stimulated the use of 14C as a tracer in the ocean.At higher latitudes, the ocean acts as a sink for CO2. In addition to Δ14C measurements, we are concerned here with dissolved inorganic carbon (DIC) and δ13C in the Norwegian and Greenland Seas. During cruises in 1989 and 1990, we obtained several Δ14C profiles, and also repeated a few GEOSECS profiles taken in 1972. The shape of these profiles changes with time, and provides information about the mixing rate and the age of the deep water. From changes in the profiles, it appears that the deep water in the Greenland Sea has obtained about 25% of the 14C concentration in the ocean surface over a period of 25 years. The Norwegian Sea deepwater is estimated to be 50–100 years older than that of the Greenland Sea.
A progress report on the Carina spiral feature
Authors: Bok B. J. , Hine A. A. , Miller E. W. 
Published: July 2016

The existing data on the distribution of O and B stars, of optical and radio H II sources, of H I and of cosmic dust have been assembled for the Carina-Centaurus Section of the Milky Way, lII = 265° to 305°. The published data have been supplemented by recent photoelectric UBV data and new photographic material. Two Working Diagrams (Figures 9 and 10) of the Carina Spiral Feature have been prepared. The Feature is sharply bounded at lII = 282° and again at lII = 295° in the range of distance from 1.5 to 6 kpc from the sun. Its outer rim is observed from the sun almost tangentially to a distance of 8 kpc from the sun. The Feature is found to bend at distances greater than 9 to 10 kpc from the sun, a result shown by both radio H I and radio H II data.Figure 9 presents our basic data for the stellar, gas and dust components of the Feature. The O and early B stars and the H II Regions are closely associated and within 6 kpc of the sun they are concentrated in the range 285° < lII < 295°. The distribution in longitude of H I is broader and spills over on both sides of the O and B and the H II peak distributions. Long period cepheids yield a concentration similar to that shown by O and B stars and H II Regions. The visual interstellar absorption between lII = 282° and 295° is represented by a value AV = 0.5 mag kpc−1, or less, applicable to distances of 4 to 5 kpc. Much higher absorption is present on the outside of the Carina Spiral Feature, 265° < lII < 280°, where total visual absorptions as great as 3.5 mags. are found at distances of the order of 2 kpc. Even heavier absorption is indicated for these longitudes at 4 kpc from the sun, thus suggesting that the heavy obscuration on the outside of the Carina Spiral Feature is a phenomenon of general structural relevance (see Figures 8 and 9). Only small values of AV are found at the inside of the Spiral Feature.The Working Diagram (Figure 10) shows that the O and B star peak and the H II peak have a width of 800 parsecs (12°) at 4 kpc from the sun, whereas the H I width is at least 1500 parsecs at the same distance. The peak of the O and B star distribution and of the H II distribution lies at about 600 parsecs (8° at 4 kpc) within the outer edge of the spiral feature. The heaviest interstellar absorption is on the outside of the Feature.
The theory of spiral structure of galaxies
Authors: Marochnik L. S. 
Published: July 2016

A Landau-type instability mechanism for generating spiral waves is suggested.Two populations of stars, Populations I and II, are considered, the second one with mean rotational velocity zero. Then a dispersion relation is derived which is reduced to the Lin-Shu dispersion relation in the case of vanishing Population II. The amplification of the wave is of the same type as the two-stream instability. It occurs if the angular velocity of the spiral pattern Ωs is smaller than the angular velocity of the Population I stars. A value of Ωs = 22–25 km s−1 kpc−1 was found, as well as the growth parameter. Spiral arms are formed in 108–109 yr, while trailing and leading waves grow at the same rate.A quasi-linear theory is developed to account for the limited growth of the spiral waves.Detailed accounts of the theory and of its implications are contained in recent publications (Marochnik, 1969; Marochnik and Suchkov, 1969a; 1969b; Marochnik and Ptitzina, 1969; Marochnik et al., 1969).
A New Optical Observatory in Turkey
Authors: Aslan Zeki , Selam Selim O. , Esendemir Akif 
Published: July 2016

Site-testing observations carried out between 1982 and 1986 have shown that Southwest and Southeast Turkey contain good potential observatory sites. The mountain known as Bakirhtepe near the Mediterranean coast was found to be a good site with a high percentage of nights with clear skies and good seeing.Here we summarize the results of the site-test observations and give general information about the site.
Electronographic Photometry of Stars in the Globular Clusters of the Magellanic Clouds
Authors: Walker M. F. 
Published: July 2016

Due to the linearity, high quantum efficiency, and high storage capacity of electronographic image intensifies, their application to astronomical photometry constitutes an advance equal in importance to those that resulted from the introduction of the photographic plate and the photomultiplier. With existing electronographic image tubes and telescopes of 60-in. aperture stellar photometry is possible to about magnitude 23. Consequently a major advance in the study of the stellar contents of galaxies in the Local Group may now be made.During 1968–69, the spectracon image intensifier was used on the 60-in. reflector of the Cerro Tololo Observatory for B, V observations of 14 globular clusters in the Magellanic Clouds. Details of the observing program and discussions of the observations so far reduced will appear shortly in papers in the Astrophysical Journal and in Sky and Telescope.
Observations of H II Regions in Sc Galaxies
Authors: Searle Leonard 
Published: July 2016

A spectral survey of Hii regions in the galaxies M33, M51, M101, NGC 2403 and NGC 1232 has been carried out. Absolute fluxes have been measured photo-electrically. The energy distribution of the embedded O-association and the intensities of the emission lines have been obtained. The emission spectra can be classified in a one-parameter sequence which is the same for all the galaxies studied. The spectral type is independent of size, shape, surface brightness and density of the Hii region, but does depend on the location of the region in its galaxy.In the galaxies surveyed there is a close correlation between the distance of an Hii region from the center of the galaxy and the appearance of its spectrum. The line ratios [OIII]/Hβ, Hα/[NII], and [OII]/[NII] all increase by large factors as one passes from regions in the inner spiral arms to those in the outermost arms. The average value of these ratios in a galaxy increases on going from early Sc galaxies to late Sc galaxies. The results show that the N/O abundance ratio (and probably also the O/H abundance ratio) is lowest in irregular galaxies and in the outer parts of late Sc galaxies. It increases towards the center of the spirals and it is highest in the inner spiral arms of the early Sc galaxies. In contrast, the He/H abundance ratio is constant across galactic disks and along the morphological sequence.
The Balmer lines in the Seyfert Galaxies NGC 5548 and NGC 4151
Authors: Weymann R. , Cromwell R. 
Published: July 2016

The profiles of the Balmer lines in NGC 5548 as reported by Dibai et al. (1968) were somewhat asymmetric, whereas those reported by Anderson (1970) are smooth and symmetric. We present profiles which are strongly asymmetric, resembling those of Dibai et al. Evidently electron scattering is not the sole principal broadening agent and we must deal with velocities ∼ 2500 km s−1 in a very small volume.The transient nature of the P-Cygni type profiles in the Balmer lines of NGC 4151 has previously been noted (Cromwell and Weymann, 1970). These lines have since disappeared, at the resolution available to us, in a time of 3 months. A model in which frequent outbursts of shells or filaments produce transient features in the Balmer lines, while the accumulated material from past outbursts produces the relatively stable HeI λ 3889 feature, seems the most plausible.
High-Resolution Observations of Variable Radio Sources
Authors: Moffet A. T. , Gubbay J. , Robertson D. S. , Legg A. J. 
Published: July 2016

Preliminary results are reported of a long-term program to test models of variable radio sources by direct observations of diameter changes. Although further confirmation is needed, increase in angular diameter attributed to a centimetric component of 3C 279 found in 1966 implies relativistic expansion with α ≳ 2.In order to sort out events taking place in variable sources it is necessary to observe frequently and at many wavelengths, especially at short wavelengths.
Radio Observations of Neutral Hydrogen in Four Seyfert Galaxies
Authors: Allen Ronald J. , Darchy Bernard F. , Lauqué Robert 
Published: July 2016

The 21-cm wavelength radiation from neutral hydrogen in NGC 1068, NGC 3227, NGC 4051 and NGC 4151 has been observed with the large radio telescope at Nanĉay, France. Since the angular sizes of these galaxies are of the same order as the telescope right ascension beam-width, no information on the angular distribution of the neutral hydrogen was obtained. However the radial velocity distribution of the total hydrogen (the ‘integrated profile’) of the whole galaxy was measured for each of the four galaxies. The hydrogen masses and total masses can be calculated from these profiles using simple models of galaxy shapes and rotation curves.Optical spectra sometimes show evidence for explosive phenomena and radial outflow of gas in the central regions of Seyfert galaxies. We have examined the integrated radio profiles for indications of large-scale radial motions of neutral hydrogen in two ways. First, for all four galaxies observed, we compare the ratios of hydrogen mass to total mass with the values obtained from other galaxies (not Seyfert) of the same morphological type. Second, for these galaxies where the optical data are available, we compare the estimates of total mass obtained from the optical spectra with the estimates based on the width of the radio profile.We conclude from these comparisons that the integrated profile of NGC 1068 is unusually broad. One possible interpretation which is qualitatively consistent with the optical data is that an appreciable fraction (about ⅓) of the neutral hydrogen content of NGC 1068 is moving radially outward with velocities of about 200 km s−1 An indication of similar phenomena (although less extreme) is obtained for NGC 4051. The widths of the integrated profiles of NGC 3227 and NGC 4151 do not seem unusual.
The Large-Scale Variations of Quasi-Stellar Objects
Authors: McCrea W. H. 
Published: July 2016

The proposition for consideration is:A QSO is an approximately standard object: it has an approximately standard history consisting mainly of an increase of optical brightness to a very high peak, and a subsequent decline. I suggest that the history has a relevant duration of about 106 yr, and that the total increase of brightness is by a factor about 103, while the mean brightness is of the order of 1% of the peak brightness (so that the peak is rather sharp).
A Matter-Antimatter Model for Quasi-Stellar Objects
Authors: Elvius Aina 
Published: July 2016

Observations of quasi-stellar objects and radio galaxies indicate that the total energy radiated from such objects is so large that the most likely source of energy is annihilation.The demand for symmetry in the universe between ordinary matter and antimatter indicates that there must be equal quantities of the two kinds of matter in every galaxy. From this it seems likely that a galaxy is born as an ambiplasma body, in which separation of matter from antimatter leads to reasonably stable configurations.The violent events observed in quasi-stellar objects are then interpreted in terms of collisions between stars of opposite kinds of matter. Such collisions are expected to occur frequently in very young galaxies with a high stellar density in the nucleus. Most of the gamma-radiation released in the annihilation will be absorbed in the gases of the colliding bodies, causing strong heating and violent explosions. Strong ionizing radiation and expanding gas clouds will give rise to the observed optical line emission. Expanding clouds of light ambiplasma will emit synchrotron radiation.
Small-Scale Solar Magnetic Fields
Authors: Stenflo J. O. 
Published: July 2016

The observed properties of small-scale solar magnetic fields are reviewed. Most of the magnetic flux in the photosphere is in the form of strong fields of about 100–200mT(1–2 kG), which have remarkably similar properties regardless of whether they occur in active or quiet regions. These fields are associated with strong atmospheric heating. Flux concentrations decay at a rate of about 107Wb s-1, independent of the amount of flux in the decaying structure. The decay occurs by smaller flux fragments breaking loose from the larger ones, i.e. a transfer of magnetic flux from smaller to larger Fourier wave numbers, into the wave-number regime where ohmic diffusion becomes significant. This takes place in a time-scale much shorter than the length of the solar cycle.The field amplification occurs mainly below the solar surface, since very little magnetic flux appears in diffuse form in the photosphere, and the life-time of the smallest flux elements is very short. The observations further suggest that most of the magnetic flux in quiet regions is supplied directly from below the solar surface rather than being the result of turbulent diffusion of active-region magnetic fields.
Double-Peaked Flare Events on red Dwarf Stars and Solar ‘Sympathetic’ Flares
Authors: Rodonò M. 
Published: July 2016

About 50% of the flare events observed on red dwarfs are at least double-peaked. As the majority of flare stars are members of double or multiple systems, the possibility that time-overlapping flares originate quasi-simultaneously on the individual components is discussed.Assuming a poissonian occurrence of flares in both components, the expected probability of observing double-peaked flares is lower than 1% for the most active binary systems.However, from photometric observations of the double flare star EQ Peg (BD +19°5116 AB) carried out by the author with an area scanner (the components' angular separation is 3.7″) about 20% of the observed flares have been found to be double-peaked flares resulting from separate flares, one in each component. A direct flare triggering of the following flare by the preceding one can be ruled out since the light travel-time between the two components is 3.5 h, while the observed time delay between the flare peaks is about 10 min. Moreover, the proximity effect does not seem to play an important triggering role.It is concluded that, although the analogy with solar ‘sympathetic’ flares is not always applicable, it is the most promising framework within which the majority of double-peaked flare events on red dwarfs must be interpreted.
Abundance Effects for the A0–G2 Stars in the Geneva System
Authors: Hauck B. 
Published: July 2016

The abundance effects on the tri-dimensional representation for the A0-G2 stars in the Geneva system are reviewed. B2–V1 anddare not affected by the Am characteristic, but B2–V1 is too blue (blocking effect on V1) anddsmaller for the Ap stars. For B2–V1 ≥ 0.230, we have a residual effect Δ(B2–V1) = 1.20 (Δm∗2+ 0.060). d is also affected and the residual effect is Δd= −0.4 Δm2for Δm2≥ −0.060 and Δd= −1.1 Δ(B2–V1) −0.024 for Δm2< −0.060.The abundance effects on the relations between B2–V1 and the parameters of temperature in other systems are studied.
Chemical Evolution of the Galactic Disk and the Radial Metallicity Gradient
Authors: Mayor M. 
Published: July 2016

An analysis of the kinematical and photometric properties of about 600dF stars and 600 gG-gK stars permits the estimation of the radial chemical gradient in the Galaxy. The mean value in the solar neighbourhood obtained for all of these stars is:
The values of [Fe/H] used for this estimation are deduced for the dF stars using uvby β photometric measurements and for the gG-gK stars from a list published by Hansen and Kjaergaard. An estimate of the chemical gradient using UBV photometry of dG stars in the solar neighbourhood gives a similar value. For all the samples studied (dF, dG or giants) the order of magnitude for the gradient is the same. However, for the youngest stars in these samples the metallicity gradient could be larger:
Such a value may be affected by dynamical perturbations of the galactic disk.The values published by Hansen and Kjaergaard for the sodium concentration in giant star atmospheres also indicate a radial galactic gradient of the same order.If only the dF stars which are sufficiently evolved to allow an age estimate are considered, then a very distinct correlation is found between age and metallicity:
An important fraction of the heavy elements actually present in the solar neighbourhood seems to have synthetized during the life of the galactic disk.The two derivatives and are not independent, but are connected by the chemical evolution of the galactic disk. Some elementary deductions show the coherency of these two estimates.The intrinsic dispersion of metallicities, at a given age and birthplace, is somewhat lower than the admitted values.
It has not been possible to find any significant variation with age of this quantity from the present observational material. The simultaneous variation of σ2w and [Fe/H] as function of age is evidence for a z stratification in the mean abundance of the heavy elements. The ratio between the mean metallicity in the plane and at z = 500 pc is estimated to be about a factor of two.Finally it is shown that the interpretation of the kinematical diagrams for different groups of given metallicity is ambiguous. A relation as e vs [Fe/H] depends not only on the chemical and kinematical history of the Galaxy but is also strongly dependent on the observational errors of [Fe/H] and on criteria used to define the sample.A paper containing the above results has been submitted for publication in Astronomy and Astrophysics.