bluuebunny/crossref_metadata_2025_split huggingface dataset:
Whirl Theory of the Origin of Galaxies and Clusters of Galaxies
Authors: Ozernoy L. M. 
Published: June 2019

This paper reviews the present state of the theory of primaeval whirls which may be responsible for the origin of galaxies and galaxy systems. The main problems on which the author will concentrate are concerned with the pre-recombination evolution of the whirls. Special attention is given to new results, obtained by Kurskov and the author, concerning the dissipation of cosmological turbulence and the constraints which follow on the parameters of primaeval whirls. In contrast to some assertions in the literature, there is not contradiction between the whirl concept and observations. Moreover, the fact that the final spectrum of motions and corresponding inhomogeneities does not depend essentially upon the details of the initial whirl spectrum makes the theory very attractive.The formation of galaxy systems (groups, clusters etc.) is discussed, and alternatives for the formation of galaxies themselves are briefly outlined. Many aspects of the whirl theory are suitable for further observational and theoretical development.
An Upper Limit to the Mass Loss from the Centre of the Galaxy
Authors: Poveda Arcadio , Allen Christine 
Published: June 2019

A mass loss of 200 M⊙ per year, as conservatively suggested if Weber is detecting gravitational waves from an isotropic source at the galactic centre, is shown to be incompatible with the existence of (a) globular clusters, (b) old wide binaries, if this loss rate has been constant over the past 1010 yr.From the orbit of ω Centauri in the galactic field and its observed mass distribution and tidal radius an upper limit to the mass loss from the galactic centre is found to be 1 M⊙ yr-1 over the past 1010 yr.
Cosmic Background Radiation Anisotropies in the Far Infrared
Authors: de Bernardis P. , De Petris M. , Epifani M. , Gervasi M. , Guarini G. , Masi S. 
Published: June 2019

The motion of the earth with respect to the distant matter frame produces a spectral distortion in the observed background radiation given by
1The second-order approximation in β gives (de Bernardis et al., 1989) 2 where α≅(dlnI/dln v) = (v/I)(dI/dv). The first term in cosθ of equation (2) is the usual dipole anisotropy, the second constant term is the equivalent of the transverse Doppler effect in special relativity, and the third term is the quadrupole anisotropy. It is interesting to note that the quadrupole term is zero in the Rayleigh-Jeans region of the blackbody spectrum: Q ≈ 1/2(3–α)(2–α)β2cos2θ.
III.—The Temple of Aphrodite: its Architectural History and Remains
Authors: Smith R. Elsey 
Published: June 2019

The history of the temple, as far as it can be ascertained from literary records from the study of ancient coins and from any similar sources, is elsewhere fully discussed; it remains to examine the actual ruins of the fabric, in order to extract from them what internal evidence there may be as to the date of the various portions from the style of workmanship and the methods of construction therein employed.It will be easier to follow this examination in connection with the plan if we systematically pursue it from the south-west corner northwards. There are two great divisions into which the work may be separated—pre-Roman and Roman. In the first of these there are certainly three subdivisions, and the Roman work shows two main divisions denoting two great periods of restorative work; but the work of all these five distinct periods is so interwoven that it is not possible to separate and make them clear on a small scale plan. The two main divisions are indicated by differences in shading on the plan opposite, and the position of the more minute subdivisions will be referred to in order as they occur.
The Bias
Authors: Jennings Jesse D. 
Published: June 2019

Now against a regional and local environmental background, I should like to present in simple narrative the Great Basin chapter of the story of man in the western hemisphere as I conceive it.There are numerous archeologic stations in the west and in the Plains where deep layers of earth, one upon the other, have yielded collections of considerable age. Man’s tools are found, particularly in the Plains, in some of these layers in direct association with animals now extinct. Taken singly these locations tell very little — they are mere paragraphs in a long chapter — about man's history as the western hemisphere was peopled. In the aggregate, however, the findings from these several sites permit a coherent if sometimes skimpy account to be built up.
Statistical Properties of Solar-Type Close Binaries
Authors: Halbwachs J.-L. , Mayor M. , Udry S. , Arenou F. 
Published: June 2019

AbstractTwo Coravel radial velocity surveys dedicated to F7-K field dwarfs and to open clusters are merged in order to investigate the statistical properties of binaries with periods up to 10 years. Thanks to the accurate trigonometric parallaxes provided by Hipparcos, an unbiased sample of spectroscopic binaries (SB) is selected. After correction for the uncertainties of the measurements, the following results are obtained: 1. The distribution of mass ratios exhibits a peak for equal-mass binaries (twins), which is higher for short-period binaries than for long-period binaries. 2. Apart from the twins, the distribution of mass ratios exhibits a broad peak from 0.2 to 0.6. 3. The orbital eccentricities of twins are slightly smaller than those of other binaries. 4. An excess of SB is observed with periods shorter than about 50 days in comparison with the Duquennoy and Mayor log-normal distribution of periods. These features suggest that close binary stars are generated by two different processes. A possible difference could come from the accretion onto the binary, for instance from a common envelope or from a circumbinary disk. Alternatively, twins could come from dynamic evolution of multiple systems. It is not clear whether the formation models are already sufficiently elaborated to reproduce our statistics.
Infrared Differential Photometry of Selected Orbital Binaries
Authors: Lampens Patricia , Prieur Jean-Louis , Argyle Robert 
Published: June 2019

AbstractHigh-angular resolution observations were acquired for a sample of F-G and K nearby orbital binaries, making use of the ADONIS instrument mounted at the 3.6m ESO telescope from La Silla observatory. The aim is to derive broad-band near-infrared colours for the individual components of those binaries which do not fit well the mean mass-luminosity relation, but which have accurate parallaxes (from the Hipparcos satellite) and high-quality orbits, thanks to many previous efforts. Such colour determinations allow component temperatures and photometric mass ratios to be derived.
Addressing Confusion in Double Star Nomenclature: The Washington Multiplicity Catalog
Authors: Hartkopf William I. , Mason Brian D. 
Published: June 2019

AbstractAdvances in instrumentation and reduction methods are blurring the historical distinctions between various classes of double stars. One result of this is increasing confusion in double star nomenclature, as the conventions followed by different observers are sometimes incompatible. The Washington Multiplicity Catalog is presented as a means of developing a single nomenclature scheme for all types of doubles, as well as a comprehensive database for all duplicity information.
VLA Observations of Disks and Jets in Young Close Binaries
Authors: Anglada G. 
Published: June 2019

AbstractWe show high-angular resolution results from VLA observations of the sources SVS 13, NGC 1333 VLA 2, and L723 VLA 2. Our results suggest that these sources are very young close (25-75 AU separation) binary systems and that the development of disks and jets can proceed in a different way for each component of the binary system.
VLA Observations of Orbital Motions in YLW 15
Authors: Curiel S. , Girart J.M. , Rodríguez L.F. , Cantó J. 
Published: June 2019

AbstractUsing high angular resolution (~ 03) Very Large Array (VLA) observations made at 3.6 cm during the period 1990 to 2002, we report the detection of proper motions in the components of the binary source YLW 15. We find absolute proper motions of the order of 15 km s-1. In addition, the relative astrometry between the two components reveals orbital proper motions that suggest that the total mass of this binary system is ~ 1.7 M⊙, and that VLA 1 is more massive than VLA 2.
Binary Star Formation and Mass Outflows: MHD Nested Grid Simulation
Authors: Machida M.N. , Tomisaka K. , Matsumoto T. 
Published: June 2019

AbstractWe study the binary star formation process from a rotating magnetized molecular cloud. We assume an isothermal cylindrical cloud in hydrostatic balance whose rotation axis and the direction of global magnetic field lines are both identical, and parallel to the cylinder axis. We added axisymmetric and non-axisymmetric density perturbations to the initial state and followed the subsequent evolutions. The evolution is characterized by three parameters: the amplitude of the non-axisymmetric perturbations, the rotation speed, and the magnetic field strength. As a result, it is found that non-axisymmetry hardly evolves in the early phase, but begins to grow after the gas contracts and forms a thin disk. There are two types of fragmentation: fragmentation from a ring and that from a bar. Thin adiabatic cores fragments if a thickness is smaller than 1/4 of the radius. For the fragments to survive, they should be formed in a heavily elongated barred core or a flat round disk. In the models showing fragmentation, outflows from respective fragments are found as well as those driven by the rotating bar or the disk.
Multiple Protostars, Jets, and the Origin of Brown Dwarfs
Authors: Clarke Cathie , Reipurth Bo , Delgado-Donate Eduardo 
Published: June 2019

AbstractThe observation that young stars are clustered in few body non-hierarchical multiple systems at very young ages has profound consequences for our understanding of the formation of stars, binaries and the disks and planets that may surround them. In this chapter we review theoretical progress made over the last decade in modeling the break up of these natal clusters and discuss a range of observational predictions that arise from these models, relating to the kinematics, binary statistics and possession of disks of both stars and brown dwarfs. We also argue that one of the most spectacular manifestations of dynamical interactions in young multiple systems should be the formation of giant Herbig-Haro flows, and present observational evidence that may be interpreted in this light.
On The Formation of Brown Dwarfs
Authors: Jiang Ing-Guey , Laughlin G. , Lin D.N.C. 
Published: June 2019

AbstractThe observational properties of brown dwarfs pose challenges to the theory of star formation. Because their masses are much smaller than the typical Jeans mass of interstellar clouds, brown dwarfs are most likely formed through secondary fragmentation processes, rather than through the direct collapse of a molecular cloud core. In order to prevent substantial post-formation mass accretion, young brown dwarfs must leave the high-density formation regions in which they form. We propose here that brown dwarfs are formed in the optically thin outer regions of circumbinary disks. Through post-formation dynamical interaction with their host binary stars, young brown dwarfs are either scattered to large distance or removed, with modest speed, from their cradles.
Summary of IAU Colloquium 191: The Environment and Evolution Binary and Multiple Stars
Authors: Guinan Edward F. 
Published: June 2019

AbstractA summary is given of the IAU Colloquium No 191 “The Environment and Evolution of Binary and Multiple Stars.” This conference was held in Mérida, Mexico during February 2003 and dedicated to Dr. Arcadio Poveda for his major contributions to binary- and multiple-star systems and dynamics. The conference was organized to discuss the major developments that are occurring in the fields of binary- and multiple-star formation, evolution, dynamics, and the environments where they form and evolve.
A Decade of Radio and X-ray Observations of SN 1993J
Authors: Van Dyk Schuyler D. , Weiler Kurt W. , Sramek Richard A. , Panagia Nino , Stockdale Christopher , Lacey Christina , Montes Marcos , Rupen Michael 
Published: June 2019

SummaryWe review ten years of radio continuum and X-ray monitoring of the Type IIb SN 1993J in M81. The supernova (SN) has been observed continuously, since only a few days after explosion, by our group with the Very Large Array at a number of radio frequencies, as well as by other groups. As a result, it is among the best-studied radio supernovae. The observed synchrotron radio emission is thought to arise from the interaction of the SN shock with the pre-SN wind-established circumstellar medium around the progenitor star. We describe the properties of the circumstellar interaction, based on the more fully-developed dataset, and compare this to our earlier characterization made in 1994. SN 1993J has also been a target of X-ray satellites, and we briefly discuss the nature of the X-ray emission and, together with the radio emission, describe the implications for the nature of the SN’s progenitor.
Imaging of SN 1993J
Authors: Alberdi A. , Marcaide J.M. 
Published: June 2019

SummarySN 1993J has been imaged with VLBI, and its angular expansion monitored, for almost ten years. The images show shell-like radio structures with almost circular symmetry. SN 1993J expands according to models of shock excited emission. The angular expansion has a changing deceleration rate and is best modeled with two different slopes. The swept-up mass estimate at an age of 3159 days (∼0.4 M⊙), comparable to the low-mass envelope, favors a binary scenario. The observed spectral index of SN 1993J has slowly flattened since age 1000 days onward (α has changed from −1 to −0.67 at an age of 2820 days).
Modeling the Radio and X-ray Emission of SN 1993J and SN 2002ap
Authors: Fransson Claes , Björnsson Claes-Ingvar 
Published: June 2019

SummaryModeling of radio and X-ray observations of supernovae interacting with their circumstellar media are discussed, with special application to SN 1993J and SN 2002ap. We emphasize the importance of including all relevant physical mechanisms, especially for the modeling of the radio light curves. The different conclusions for the absorption mechanism (free-free or synchrotron self-absorption), as well as departures from an ρ ∝ r−2 CSM, as inferred by some authors, are discussed in detail. We conclude that the evidence for a variation in the mass loss rate with time is very weak. The results regarding the efficiencies of magnetic field generation and relativistic particle acceleration are summarized.
Detection of the Binary Companion to the Progenitor of SN 1993J
Authors: Smartt S.J. , Maund J.R. , Kudritzki R.P. , Podsiadlowski P. , Gilmore G. 
Published: June 2019

SummaryWe present a detailed late-time photometric and spectroscopic study of SN1993J with HST/ACS and Keck LRIS-B. We find a clear signature of a hot star component in the spectra of SN1993J which cannot be explained by the surrounding faint blue stars. This is the first detection of the expected massive binary companion to the red supergiant progenitor and confirms that SN1993J did indeed arise in an interacting binary system.
Supernova Spectra
Authors: Turatto Massimo 
Published: June 2019

SummaryIn this paper are summarized the main advances of the last years in the field of SN spectra . The arguments against a monodimensional sequence for SNIa are discussed as well as the efforts to improve the temporal and spectral coverage of this kind of SNe, with the aim to understand the physics of the explosions for their use as cosmological distance indicators. Although variety is the main character of core-collapse SNe, we have been recently surprised by both exceptionally under and over-energetic explosions. The main properties of these two extreme subclasses are here reviewed.
Nucleosynthesis in Black-Hole-Forming Supernovae
Authors: Nomoto K. , Maeda K. , Umeda H. , Tominaga N. , Ohkubo T. , Deng J. , Mazzali P.A. 
Published: June 2019

SummaryStars more massive than ~ 20 − 25 M⊙ form a black hole at the end of their evolution. Stars with non-rotating black holes are likely to collapse “quietly” ejecting a small amount of heavy elements (faint supernovae). In contrast, stars with rotating black holes are likely to give rise to very energetic supernovae (hypernovae). We present distinct nucleosynthesis features of these two types of “black-hole-forming” supernovae. Nucleosynthesis in hypernovae is characterized by larger abundance ratios (Zn, Co, V, Ti)/Fe and smaller (Mn, Cr)/Fe than normal supernovae, which can explain the observed trend of these ratios in extremely metal-poor stars. Nucleosynthesis in faint supernovae is characterized by a large amount of fall-back. We show that the abundance pattern of the recently discovered most Fe-poor star, HE0107-5240, and other extremely metal-poor carbon-rich stars are in good accord with those of black-hole-forming supernovae, but not pair-instability supernovae. This suggests that black-hole-forming supernovae made important contributions to the early Galactic (and cosmic) chemical evolution. Finally we discuss the nature of first (Pop III) Stars.
Synthetic Spectra for Type Ia Supernovae at Early Epochs
Authors: Sauer D.N. , Pauldrach A.W.A. , Hoffmann T. , Hillebrandt W. 
Published: June 2019

SummaryWe present the current status of our construction of synthetic spectra for type Ia supernovae. These properly take into account the effects of NLTE and an adequate representation of line blocking and blanketing. The models are based on a sophisticated atomic database. We show that the synthetic spectrum reproduces the observed spectrum of ‘normal’ SN-Ia near maximum light from the UV to the near-IR. However, further improvements are necessary before truly quantitative analyses of observed SN-Ia spectra can be performed. In particular, the inner boundary condition has to be fundamentally modified. This is due to the dominance of electron scattering over true absorption processes coupled with the flat density structure in these objects.
Optical and Near-IR Observations of SN 1998bw
Authors: Patat Ferdinando 
Published: June 2019

Thus, the observation of gamma-ray line emission from a young supernova seems very promising in the near future. The observation, or even a null observation at a low threshold, will give significance in the fields of nuclear astrophysics and supernova theory. The scientific importance of a positive measurement would be analogous with and comparable to the importance of successful detection of neutrinos from the Sun.Clayton, Colgate, and Fishman [2].
SN 1998bw and Other Hyperenergetic Type Ic Supernovae
Authors: Mazzali Paolo A. , Nomoto Ken’ichi , Deng Jinsong , Maeda Keiichi , Iwamoto Koichi , Filippenko Alexei V. , Foley Ryan T. 
Published: June 2019

SummaryThe properties of the best-observed peculiar, SN 1998bw-like Type Ic supernovae (sometimes called “hypernovae” ) are reviewed, starting from SN 1998bw itself and including SNe 1997ef and 2002ap. Analysis of the light curves and the spectra shows that, while these SNe display a range of properties (kinetic energy, mass of the ejecta, mass of 56Ni synthesized in the explosion), they have in common a larger-than-normal explosion kinetic energy, giving rise to the characteristic broad-lined spectra. Also, they all come from the collapse of bare CO cores of massive ( ≳ 20M⊙) progenitor stars. Some of the properties of these SNe, such as kinetic energy and mass of 56Ni, are probably correlated with the mass of the progenitor. Evidence that these powerful events are intrinsically asymmetric, suggesting that a correlation with at least some gamma-ray bursts can be expected, is also discussed.
How Common are Engines in Ib/c Supernovae?
Authors: Berger Edo 
Published: June 2019

SummaryThe association of γ-ray bursts (GRBs) and core-collapse supernovae (SNe) of Type Ib and Ic was motivated by the detection of SN 1998bw in the error box of GRB 980425 and the now-secure identification of a SN 1998bw-like event in the cosmological GRB 030329. The bright radio emission from SN 1998bw indicated that it possessed some of the unique attributes expected of GRBs, namely a large reservoir of energy in (mildly) relativistic ejecta and variable energy input. Here we discuss the results of a systematic program of radio observations of most reported Type Ib/c SNe accessible to the Very Large Array, designed to determine the fraction of Type Ib/c SNe driven by an engine. We conclude that: (i) the incidence of such events is low, < 3%, and (ii) there appears to be a clear dichotomy between the majority of hydrodynamic explosions (SNe) and engine-driven explosions (GRBs).
The Radio Afterglows of Gamma-Ray Bursts
Authors: Frail Dale A. 
Published: June 2019

SummaryRadio afterglow observations continue to provide complementary and sometimes unique diagnostics on gamma-ray burst explosions, their progenitors and their environments. In this review we will first describe current search strategies and the observational properties of the detected sample. In the second part of this review we will follow the evolution of a typical radio afterglow, describe the diverse phenomenology that is observed, and interpret these observations within the framework of the fireball model.
Particle Acceleration in Gamma-Ray Bursts
Authors: Kirk J.G. 
Published: June 2019

SummarySimple kinematic theories of particle acceleration at relativistic shocks lead to the prediction of a high-energy spectral index of −1.1 for the energy flux of synchrotron photons. However, several effects can change this picture. In this paper I discuss the effect of magnetic field generation at the shock front and, by analogy with the Crab Nebula, suggest that an intrinsic break in the injection spectrum should be expected where the electron gyro radius is comparable to that of protons thermalized by the shock.
The First Steps in the Life of a GRB
Authors: Aloy Miguel A. 
Published: June 2019

SummaryWe present some preliminary results of relativistic hydrodynamic simulations of post-neutron star merger disks as potential candidates for progenitors of short-lasting gamma-ray bursts. We discuss some of the generic conditions under which a gamma-ray burst can be initiated in this kind of progenitor and the main characteristics of the resulting outflow.
The Standard Candle Method for Type II Supernovae and the Hubble Constant
Authors: Hamuy Mario 
Published: June 2019

SummaryThe “standard candle method” for Type II plateau supernovae produces a Hubble diagram with a dispersion of 0.3 mag, which implies that this technique can produce distances with a precision of 15%. Using four nearby supernovae with Cepheid distances I find H0(V)=75±7, and H0(I)=65±12.