bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Complex Nature of the Seyfert Galaxy NGC 7592
Authors: Rafanelli Piero , Marziani Paolo 
Published: July 2016

NGC 7592 = VV 731 = MCG-01-59-017 is a system of close interacting galaxies. Two main galactic bodies are present in the CCD R-band image taken at the 1.8m, F/9 telescope of the Asiago Observatory and shown in Figure 1:• a north-western (NW) component (≡VV 731B), whose starlike nucleus (A) shows a Seyfert-type spectrum (Archipova et al., 1981). A is surrounded by a nearly spheroidal envelope, with an extension in the west at P.A. = 290° detected up to a distance from A of ≈ 9 arcsec, which corresponds to ≈ 2.5h-1kpc of projected linear distance (1 arcsec ≈ .35 h-1kpc at the redshift z = 0.0244; H0 = 100 h km s-1Mpc-1). This extension seems to bend in the northern direction and to join a bright wing, detected up to « 22 arcsec from A, which turns to east and resembles a spiral arm or a tidal tail.• The envelope around A is connected (over ~ 20 arcsec 7h-1kpc) to a second galactic body (SE) located in the south-east of it. Its nucleus (B), identified by Markarian and Lipovetskii (1976) as the nucleus of Mkn 928, is located at dAB ~ 11 arcsec(~ 4h-1kpc) from A at P.A. = 100°. The morphology of this component is highly peculiar. In the central region, B is linked to two fainter knots which extend up to d″ ~ 4 arcsec at P.A. — 90°. This structure gives to the region surrounding B an elongated and distorted shape. Moreover, a bar-like structure is detected on either sides of B. The north-eastern side of the bar (P.A. = 40°) joins a slightly distorted loop of condensations, which can be traced from P.A. = 335° (at a distance from B«6 arcsec % 2.1 h-1kpc) to P.A. = 100° and from P.A. = 200° to P.A. = 240°, but not in corrispondence of the contact region between the two galaxies. This structure seems to be drained and distorted in the direction of a third condensation C at dBC ≈ 11.7 arcsec (≈ 4.1 h-1kpc) from B at P.A. — 212°. A faint plume bent in a direction opposite to that expected for spiral arms of the SE galaxy appears to extend from the west side of C.
Global Effects of Interactions on Galaxy Evolution
Authors: Kennicutt Robert C. 
Published: July 2016

AbstractRecent observations of the evolutionary properties of paired and interacting galaxies are reviewed, with special emphasis on their global emission properties and star formation rates. Data at several wavelengths provide strong confirmation of the hypothesis, proposed originally by Larson and Tinsley, that interactions trigger global bursts of star formation in galaxies. The nature and properties of the starbursts, and their overall role in galactic evolution will also be discussed.
A Dynamical Proximity Analysis of Interacting Galaxy Pairs
Authors: Chatterjee Tapan K. 
Published: July 2016

AbstractUsing the impulsive approximation to study the velocity changes of stars during disk-sphere collisions and a method due to Bottlinger to study the post collision orbits of stars, the formation of various types of interacting galaxies is studied as a function of the distance of closest approach between the two galaxies.
Typical Motions in Multiple Systems
Authors: Anosova Joanna 
Published: July 2016

In very old times, people counted – one, two, many. I want to show you now that they were right.Let’s consider the motions of isolated bodies:
1. N = 1 - simple motion;2. N = 2 - Keplerian orbits;3. N = 3 - this is the difficult problem. In general, this problem can be studied only by computer simulations.
Multiplicity Among the Young Stars
Authors: Simon M. 
Published: July 2016

AbstractOur survey for companions of the young stars now includes 45 systems in the Taurus star-forming region (SFR) and 21 in the Ophiuchus SFR. It is carried out by lunar occultation and imaging in the IR and can identify binaries in the separation range 0″.005 to 10″ in systems brighter than K=10 mag. The observed multiplicity in Taurus is ~1.6 stars/system which is comparable to that of the nearby solarlike stars but corrections for incompleteness increase the multiplicity to at least 1.8.Inner active disks are equally represented among the single and multiple systems. The multiple systems have less massive outer disks than the single systems, but there are significant exceptions. The binary UZ Tau W contains a circumstellar disk or disks of mass ~0.024 M⊙ and size ~13 AU. The quadruple GG Tau system has a remarkably extensive circumbinary disk of mass ~ 0.07M⊙. These mass estimates are comparable to the minimum values required for the proto-planetary disk of the Solar System.The specific angular momenta of the most widely spaced binaries in our sample adjoin the lowest values that can be measured for molecular cloud cores. The actual distributions probably overlap which suggests that the origin of the angular momentum of binaries is in their molecular cloud birthplaces.
Orbital Circularization in Binaries with A-Type Primary Stars
Authors: Matthews Lynn D. , Mathieu Robert D. 
Published: July 2016

It has long been recognized that tidal interaction between the components of close binaries will tend to circularize their orbits (e.g., Darwin 1879; Zahn 1977). In fact observations show an abundance of circular orbits in binaries with periods of days. However, the dissipation mechanism required for circularization, the timescales involved, and the dependence on period, mass, evolutionary state, and initial eccentricity of the system remain subjects of debate.Circularization theories such as Zahn (1977) state that circularization in binaries where at least one component possesses a convective envelope is much more efficient than in binaries where both stars have radiative envelopes. Giuiricin et al. (1984; GMM) studied the period-eccentricity distribution of O-, B- and A-type binaries and argued that the observations were consistent with Zahn’s theory for radiative envelopes. But recently, Tassoul (1988) has presented an alternative circularization theory with similarly efficient circularization in radiative- and convective-envelope binaries. In addition, period-eccentricity distributions for many samples of main-sequence convective-envelope binaries are now available. Here we reconsider the observed short-period eccentricity distribution of radiative-envelope binaries in light of these new observations and theory. Specifically, we investigate the period-eccentricity distribution of a sample of binaries with A-type primary stars.
Databases of Interest to Double– and Multiple–Star Observers
Authors: Warren Wayne H. 
Published: July 2016

AbstractA large collection of machine–readable catalogs containing data for various types of double– and multiple–star systems has become available over the last decade or so. These catalogs can be divided logically into general compilations of multiple–star data for visual systems and other collections of information for particular classes of binaries, such as cataclysmic, eclipsing, interferometric, spectroscopic, etc. A few large databases containing double– and multiple–star data have also become accessible over the last few years. This paper gives a general overview of some of the more important machine–readable catalogs and databases available, and includes a brief description of the information that each contains. The potential for what can become available in the near future, just by incorporating current information into a system providing full data retrieval, is also discussed.
Differential Photometry of Binary Stars
Authors: Dick J.S.B. , Devaney M.N. , Jones D.H.P. , ARGYLE R.W. 
Published: July 2016

AbstractUsing a short exposure, one dimensional area scanner, a programme of photometry on binary stars with separations <10″ has been initiated; using speckle techniques, photometry of binaries with separations <1″ is possible. We describe the equipment and techniques and present results acquired during commissioning.
Zeta Cancri
Authors: Harrington Robert S. , Douglass Geoffery G. , Worley Charles E. 
Published: July 2016

AbstractZeta Cancri is a multiple system in which the well-observed orbit is an inner, or close one. Three-body coupling effects are an order of magnitude more significant for the close orbit in a hierarchical system, and they must be included. An exact numerical integration is very easy and requires no approximations. Inclusion of these effects improves the residuals for this system.
A CCD Optical Search for Visual Very Low–Mass Companions of Halo Stars
Authors: Martin Eduardo L. , Rebolo Rafael 
Published: July 2016

AbstractWe have begun a search for faint companions to cataloged G/K metal–deficient dwarfs. The main goals of this investigation are:i)to collect a database of halo M-type starsii)to study the frecuency of binary separations in the range 1″ - 50″ for Population II starsiii)to find some metal-poor very–cool dwarfs that may serve as references to investigate the low-mass end of the halo main sequence.In this paper we present the first results from VRI CCD photometry of a subset (51 stars) of our sample. We have identified 7 possible very low mass companions (angular separations 1″.5 – 30″) of halo subdwarfs with [Fe/H] in the range from −0.8 to −2.6.
Strømgren Photometry of Wide Visual Double Stars with G–Type Primaries, Most of Which Have Common Origin Components
Authors: Sinachopoulos D. , Van Dessel E. 
Published: July 2016

AbstractWe have performed uvby aperture photometry of wide visual double stars with G–type primaries. We chose our pairs in order to have minimum angular separation of their components 10″ and mainly less than 20″. It is shown that both components have similar photometric parameters. We infer that most of these double stars have components of common origin.
Photometric Systems
Authors: Bessell Michael S. 
Published: July 2016

AbstractMulticolour photometry has historically been carried out within a variety of standard systems. With the advent of new detectors with different wavelength sensitivities to those of the original system and the use of subsets of secondary standards, many subtle and not so subtle changes have occurred to the original systems. However, by reverse engineering, the passbands of the modified standard systems can be determined which enables good realisation of theoretical colours and better passband matching for CCD-based photometry. In this paper, the various photometric systems will be discussed and compared and strategies will be outlined for ensuring that precise relative photometry is maintained in the future, in particular from area detectors.
Vilnius Photometry in the Southern Hemisphere
Authors: Dodd R.J. , Forbes M.C. , Sullivan D.J. 
Published: July 2016

AbstractThe seven intermediate passband filters of the Vilnius photometric system enable a more comprehensive and discriminating classification of stellar objects than is possible in broadband systems. To date, a lack of suitable standard stars has inhibited its use in the Southern Hemisphere. We have an established programme for extending the network of northern Vilnius standards into the southern skies. This paper briefly summarizes the characteristics of the Vilnius system, provides a synopsis of the data obtained on over 200 standard stars so far and presents preliminary CM and CC diagrams for the open cluster Omicron Velorum (IC2391).
Absolute Spectrally Continuous Stellar Irradiance Calibration in the Infrared
Authors: Cohen Martin , Walker R.G. , Barlow M.J. , Deacon J.R. , Witteborn F.C. , Carbon D.F. , Augason G.C. 
Published: July 2016

AbstractWe present first efforts to establish a network of absolutely calibrated continuous infrared spectra of standard stars across the 1-35μm range in order to calibrate arbitrary broad and narrow passbands and low-resolution spectrometers from ground-based, airborne, balloon, and satellite-borne sensors. The value to photometry of such calibrated continuous spectra is that one can integrate arbitrary filters over the spectra and derive the stellar in-band flux, monochromatic flux density, and hence the magnitude, for any site. This work is based on new models of Sirius and Vega by Kurucz which were calculated by him, for the first time, with realistic stellar metallicities and a customized finely-gridded infrared wavelength scale. We have absolutely calibrated these two spectra and have calculated monochromatic flux densities for both stars, and isophotal wavelengths, for a number of infrared filters. Preliminarily, the current IRAS point source flux calibration is too high by 2, 6, 3, and 12% at 12, 25, 60, and 100μm, respectively.
CCD Standard Fields
Authors: Jones D.H.P. 
Published: July 2016

AbstractThere are several standard fields for CCDs available in the literature. Some of these have been observed many times with the CCD cameras of the Isaac Newton Group of Telescopes on La Palma. These observations were made in order to establish the zero-points and colour equations for the U BV RI filters. Now that many observations are available in the data archive it is possible to combine them and search for inconsistencies in the published magnitudes and colours. This discussion will lead to standard fields of a higher quality. Furthermore astrometric plates have been taken of several of these fields which will be used to provide accurate positions as well as magnitudes and colours. These will provide the scale, orientation and distortion of any CCD camera.
High-Precision Photometry
Authors: Young A.T. 
Published: July 2016

AbstractThe current precision of differential comparisons, within a fixed instrumental system, reaches about a millimagnitude. The current accuracy of transformations between systems is on the order of 0.01 mag, but is worse in some cases. The transformation errors are due to mis-matches between instrumental and standard systems, and cannot be transformed away without further information. A simple geometric model is proposed, which illuminates the transformation problem, and suggests means of minimizing it. Misplaced band edges are the main cause; tighter specifications on filters will help to reduce these errors. The ultimate solution is to use sampled systems in which some bands look like the derivatives of their neighbors. This automatically produces enough band overlap to comply reasonably well with the sampling theorem.
Problems of CCD flat fielding
Authors: Tobin William 
Published: July 2016

AbstractCCD flat fielding using an illuminated dome screen is discussed. Rings of reduced response caused by dust specks on the cryostat entrance window indicate the required uniformity of screen illumination but may not divide satisfactorily because of telescope flexure. Illumination colour is important for shorter-wavelength, broad-band filters. Flat fields can be distorted significantly by light scattered off telescope baffles. Special precautions are needed for uv flat fielding. The Mt John TH 7882 CDA chip is slightly sensitive to polarisation. Dome flat-fielding accuracy of 0.3% would seem achievable.
“Differential Speckle Interferometry”, a New Tool for Double Star Research
Authors: Beckers Jacques M. 
Published: July 2016

AbstractSpeckle interferometry is a powerful tool for close binary star research allowing angular resolutions as small as 20 milliarcsecond. A technique is proposed to resolve spectroscopic binaries with even smaller separations. It uses the fact that speckle images taken in one or the other of the Doppler shifted spectral lines give a different intensity weighting of the two components of the binary. The location of the speckles in the two speckle images is therefore different, the direction of the displacement being related to the position angle of the binary, the amount of the displacement being related to its separation. Since the location of speckles can be determined with a much higher precision than their diameter, this creates the possibility for submilliarcsecond observations. This paper describes an experiment being started now to use this so-called “Differential Speckle Interferometry” technique for the study of binaries, stellar rotation, stellar chromospheres, Ap stars and other objects.
Shift-and-dd-Type Algorithms and their Application to Capella
Authors: Bagnuolo William G. 
Published: July 2016

Bates and Cady (1980) proposed a method for astronomical image reconstruction that involves superimposing regions about the brightest pixels of each frame produced by speckle interferometric techniques. Unlike the method of Lynds, Worden, and Harvey (1976), no attempt is made to center apparent speckle images before superposition. This method is hereafter referred to as “shift-and-add” (SAA). The simplicity of this method makes it highly suitable for analysis and simulation.This paper summarizes the application of extensions of SAA to the problem of determining reliable double star intensity ratios. Theoretical and simulation results presented in a previous paper (hereafter called “paper I”) by Bagnuolo (1982) will be summarized. In addition, the results of the application of SAA-type algorithms to Capella will be presented.
Long Baseline Interferometry and Binary Stars
Authors: Davis John 
Published: July 2016

AbstractThe observations of α Vir with the Narrabri Stellar Intensity Interferometer demonstrated the potential of long baseline interferometry for the determination of fundamental properties of double-lined spectroscopic binary systems. Since the completion of the programme with the Narrabri instrument the Chatterton Astronomy Department has been conducting a study aimed at developing a stellar interferometer with limiting magnitude V ≳ +8 and maximum baseline ≳ 1 km (resolution at 500 nm ≲ 7 × 10−5 seconds of arc). The way in which a long baseline interferometer may be used in the study of binary stars is outlined, the requirements for this work are discussed, and the current status and future plans of the Chatterton Astronomy Department’s programme to develop a new long baseline interferometer are summarised.
The Faint Object Camera
Authors: Rakos Karl D. 
Published: July 2016

The Space Telescope (ST) is one of the most exciting projects presently planned in space astronomy. It will make a considerable contribution to astronomical research throughout the rest of this century. The high resolution 2.4 m telescope will be placed in orbit probably in 1985 by the Space Shuttle and will provide an astronomical capability unattainable by the ground-based telescopes.The European Space Agency decided to participate in this NASA programme in 1976. ESA’s part in the programme includes the production of a major subsystem (the solar arrays and associated mechanisms), the building of the Faint Object Camera, and future participation in the operational activities and in the running of the Space Telescope Science Institute.
The Nature of the Local Group
Authors: Aparicio Antonio 
Published: July 2016

AbstractThe Local Group provides an interesting and representative sample of galaxies in the rest of the Universe. The high accuracy with which many problems can be addressed in Local Group galaxies is of paramount importance for understanding galaxy formation and evolution. This contribution presents a short review of overall Local Group properties followed by short discussions of five topics in which the study of Local Group members provides particularly significant information. These topics are only examples of the usefulness and potential of Local Group research. The five selected topics are the formation of the Milky Way, galaxy destruction and tidal streams, detailed galactic chemical evolution, star formation history determination, and low surface brightness extended structures.
The Araucaria project – improving stellar distance indicators
Authors: Pietrzyński Grzegorz , Gieren Wolfgang 
Published: July 2016

AbstractWe present first results of an optical wide field imaging survey of the galaxies NGC 300, NGC 6822, WLM and Phoenix, performed as part of the Araucaria Project, a long-term observational program recently initiated at the Universidad de Concepción. Based on our data, a large number of new Cepheids in these galaxies has been found. Our photometric databases were also used to select blue supergiant candidates in these galaxies, and to search for the photometric variability of these stars, as well as for a number of side projects, such as the search of other types variable stars and OB associations in these galaxies.
Age dependence of the vertical distribution of Cepheids
Authors: Dambis A.K. 
Published: July 2016

AbstractThe wavelike oscillations of the vertical scale height of the local population of classical Cepheids located at Galactocentric distances R0 – 1 kpc < Rg < R0 + 1 kpc is analyzed using Cepheid ages computed in terms of evolutionary models of Pols et al. (1998) with and without the allowance for convective overshooting. The resulting periods of vertical oscillations of stars about the galactic plane are found to be PZ = 74 ± 2 Myr and PZ = 104 ± 2 Myr for standard models and models with overshooting, respectively. If interpreted as a manifestation of vertical virial oscillations, the pattern found implies local mass density values of ρstd = 0.118 ± 0.007 M⊙ pc−3 and ρovs = 0.060 ± 0.004 M⊙ pc−3, respectively. The latter value is totally incompatible with recent estimates based on Hipparcos data and the former value, combined with recent estimates of the local density of visible matter, sets an upper limit of 0.023 M⊙ pc−3 for the local density of dark matter.
The distribution of novae in the Magellanic Clouds
Authors: Shida Raquel Yumi , Liller William 
Published: July 2016

AbstractSome 34 novae have been discovered in the LMC and 14 in the SMC. Historically, the novae seemed to avoid the central bar of the LMC and the main body of the SMC, but with the novae discovered in the past two decades a different picture emerges. The more dramatic situation exists in the SMC where all seven of the most recent novae have occurred in or very near the main body. Indications are that the age of the LMC bar is around 5Gyr (Smecker-Hane et al. 2002), certainly old enough to breed novae. Perhaps the puzzle now is why there have been so many novae in the disk component of the LMC where many HII regions are found.
Pulsating white dwarfs as astrophysical tools
Authors: Sullivan Denis J. 
Published: July 2016

AbstractThe study of pulsating white dwarfs is a scientifically productive exercise as their measured pulsation characteristics yield both unique data on their interiors and also shed light on more general astrophysical questions. The modelling process is simplified due to their assumed chemically homogeneous and layered structures. As well as being archaeological remnants of their nuclear burning progenitors, white dwarfs are cosmic laboratories that can provide some observational constraints on theories of matter in regions of phase space that are unattainable in laboratories on Earth. The hotter white dwarfs should feature neutrino production by several unusual weak interaction processes, while their cooler cousins should exhibit core crystallization. White dwarf pulsators are very stable in period (if not always in amplitude) and suitable objects can be used as sensitive orbiting clocks in a search for stellar companions, including those of planetary size. Finally, the ensemble of cooling white dwarfs can be used as an independent cosmic chronometer over very long timescales if the cooling curve is properly calibrated. The pulsators make important contributions in this regard.