bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary Orbits from Velocities with the CCD-Echelle Spectrometer at Lick
Authors: Popper Daniel M. 
Published: July 2016

The Hamilton CCD-echelle spectrometer at the coudé focus of the 3-m Shane telescope of the Lick observatory has been described by Vogt (1987). Illustrations of some binary star spectra obtained with this instrument are given by Popper & Nelson (1990, B-type binaries with large magnitude differences) and by Popper (1992, G-type eclipsing binaries), where typical cross-correlation functions are also shown.In this progress report, I give some initial preliminary orbital results. First is the bright early B binary, VV Ori, the orbits of which have been the subject of considerable controversy (Duerbeck 1975, Andersen 1976, Popper 1981). According to Chambliss & Leung (1982) and to the line ratios, the secondary component contributes about 10% of the light of the system in the visual region. Multiple (2 to 4) exposures of VV Ori have been obtained with the Hamilton on 7 nights. Velocities of the primary are determined from 13 lines, primarily of OII and HeI between 440 and 590 nm. The only lines found to be useful for the secondary are HeI 597.5 and 492.1. Analysis of the velocities is complicated by the poorly determined variation of the center-of-mass velocity, with a range of roughly 26 km s−1 and a period of roughly 120 days (e.g., Duerbeck 1975). Preliminary orbits based on this material lead to masses 11.1 and 4.7.M⊙, to be compared to Duerbeck’s values of 7.7 and 3.4. It is primarily the high signal/noise ratio, over 600, that enables this study to be carried out satisfactorily.
Gravitational Instabilities in Circumstellar Disks and the Formation of Binary Companions
Authors: Adams Fred C. , Benz Willy 
Published: July 2016

AbstractWe review recent work on gravitational instabilities in circumstellar disks and discuss implications for the possibility of forming binary companions within these disks. Linear stability analysis indicates that self-gravitating modes with azimuthal wavenumber m = 1 will grow strongly in star/disk systems with the physical properties observed in astrophysical systems. Smooth particle hydrodynamic simulations indicate that these self-gravitating instabilities (with m = 1 and higher) will grow into the nonlinear regime. In many cases, a spiral arm will collapse into a gravitationally bound “knot” of gas; these knots typically contain 1% of the mass of the disk and travel on elliptical orbits about the central star.
The Fragmentation Mechanism
Authors: Boss Alan P. 
Published: July 2016

AbstractBinary and multiple star systems may form by fragmentation, that is, through break-up of a dense molecular cloud core during the dynamical collapse phase that leads to the formation of protostellar objects. This review concentrates on theoretical models of fragmentation based on numerical hydrodynamical calculations in three spatial dimensions, using both finite-difference and smoothed particle hydrodynamics techniques. A variety of recent results are described, including calculations of the fragmentation of bar-like (prolate) clouds, fragmentation in clouds with initial power-law density and angular velocity distributions, tidally-induced fragmentation, fragmentation in cooling clouds, formation of hierarchical systems, and the dividing line between clouds that fragment and those that appear to form single protostars. A brief comparison of the predicted physical and dynamical properties of the theoretical fragments with the observed properties of main-sequence and pre-main-sequence binary stars lends supports to the hypothesis that fragmentation is the dominant formation mechanism for binary and multiple star systems. The major uncertainties regarding fragmentation are the extent to which precollapse clouds are susceptible to fragmentation, and the degree to which binary fragments undergo orbital decay and possibly mergers through interactions with the enveloping disk.
The Formation of Non-Equal Mass Binary and Multiple Systems
Authors: Bonnell Ian , Bastien Pierre 
Published: July 2016

AbstractCalculations of the formation of non-equal mass binary and multiple systems are presented. Binary formation results from the elongated shape of the initial cloud, one fragment forming on each side of the equatorial plane. Slight linear density gradients along the cloud’s major axis are sufficient to form non-equal mass fragments. Resultant mass ratios range from 0.1 to 1.0, in agreement with observations.In the presence of rotation, the fragments form with surrounding disks. The primary forms with a larger disk than does the secondary. Due to it’s orbital motion around the primary, the secondary can directly accrete the matter that has gathered in the primary’s disk. The secondary is thus less likely to have an appreciable disk, accounting for a redder primary. The binary system’s initially high eccentricity decreases with the continued accretion of higher specific angular momentum at apastron and lower specific angular momentum matter at periastron. Non-coplanar multiple systems with unequal mass components are also formed. The systems are composed of an inner binary and a more distant companion. The mass ratio of the companion binary system is usually less than that of the binary.
A Review of Dynamical Studies of Multiple Stars
Authors: Harrington Robert S. 
Published: July 2016

This is not going to be an exhaustive review of all of the literature on the subject of multiple star dynamics, although I will call your attention to the very recent review by Valtonen & Mikkola (1991) entitled “The Few-Body Problem in Astrophysics”. After all, from a dynamical point of view a multiple-star system is the physical realization of the n-body problem of celestial mechanics, and an enormous literature exists for that subject. Rather, this will be some personal thoughts on aspects of the few-body problem that are particularly relevant to the multiple-star astronomer.One should not forget the case of n=2. Although the problem is completely solvable and contains no surprises, it is one of our reasons to exist. Especially if a binary is on a photographic program, which can yield a parallax, a total mass, and a mass-ratio, and if photometry exists, as is usually the case now for parallax stars, a real contribution is possible. Do an orbit, which is the dynamical problem, and you have two more good points for the empirical mass/luminosity relationship, which is not a bad day’s work for the astrophysicist.
Visual Binary Orbit Calculation with the Help of a PC: One Possible approach
Authors: Ćatović Z. , Olević D. 
Published: July 2016

AbstractIn this work we suggest one possible approach to “computerization” of the process of the visual double star orbit determination. Our computer program, based on the original method (Olević 1989), is interactive which means that the calculator of the orbit makes the final decision about the choice of the best orbit.
The Apparent Galactic Disc Scale Height
Authors: Kroupa Pavel 
Published: July 2016

Abstract For stars fainter than Mv ≈ 6 the density distribution perpendicular to the Galactic midplane can be approximated by an exponential fall-off with a scale height of about 270 pc. We show that even if in fact constant an apparent decrease of the scale height to about 150 pc for stars with Mv ≈ 17 can be expected if all ‘stars’ measured in the photographic surveys are unresolved binaries. In principle measurements of the apparent scale-height allow the study of the mass-ratio distribution and the proportion among ‘stars’ of binary systems.
Binary Stars in Praesepe
Authors: Kroupa Pavel , Tout Christopher A. 
Published: July 2016

AbstractIn open clusters the scatter about the single-star main sequence is usually negligible. However, unresolved binary systems are brighter and redder than single stars, and thus some ‘stars’ appear shifted away from the main sequence. We make very simple models of the Praesepe cluster, and find evidence that low-mass systems prefer independent component masses, whereas systems of higher mass than the sun appear to favour some correlation towards equal-mass components.
Miras Without Masers are Symbiotic Stars
Authors: Lewis B.M. 
Published: July 2016

AbstractAbout 40% of potential OH / IR stars, color selected from the IRAS Point Source Catalog, have no 1612 MHz masers. While these objects are rarely carbon rich, they are usually associated with circumstellar shells. The natural explanation for these “OH / IR star color mimics” is that they are systems with a degenerate companion collecting an accretion disk from a red giant wind. This provides them with an extra source of UV for dissociating their molecules. The persistent absence of the usual complement of masers from an O-rich shell is then a pointer to the presence of a degenerate companion. These occur in association with ~45% of old giant stars.
Calibration of the Mass-Luminosity Relation Using Trigonometric Parallaxes. I
Authors: Van Altena William F. , Girard Terrence M. , Lee John T. 
Published: July 2016

AbstractThe calibration of luminosities using trigonometric parallaxes introduces well-known errors that are a function of the ratio of the parallax error to the parallax, when the sample is chosen from stars with measured parallaxes larger than some minimum parallax. In this paper it is shown that similar errors are also introduced into the mass axis of the mass-luminosity relation (MLR) and can result in a biased MLR. The bias is shown to be related to the Lutz-Kelker correction to the absolute magnitude, as extended by Hanson for the case of selection effects in the data sample. The size of the correction in the mass axis is substantial and for the case of a uniform distribution in space, it can amount to a multiplicative factor of 1.17 in the mass for a ten sigma (σ/π = 0.10) parallax and a factor of 1.62 for a five sigma (σ/π = 0.20) parallax.
The Astrometric Study of ADS 48 — a Nearby Double Star with a Probable Invisible Satellite
Authors: Kiyaeva O.V. 
Published: July 2016

AbstractThe orbit of the visual double star ADS 48 AB is determined on the basis of Pulkovo and Washington sets of observations. The similar deviations in observations of the both sets are discovered. It may be explained by the existence of the invisible satellite with a mass about 0.0lM⊙.
Searching for Low–Mass Companions with the HST WF/PC
Authors: Baum William A. 
Published: July 2016

AbstractOwing to the spherical aberration of the Hubble Space Telescope, prospects are now poor for the astrometric detection of low–mass companions of nearby stars with the Wide–Field / Planetary Camera. The installation of a new camera (WF/PC-II) incorporating an optical correction for the telescope will only partially recover the low–mass companion search capability.
Detection and Measurement of Binary Stars with the HST Fine Guidance Sensors
Authors: Franz O.G. , Kreidl T.J. , Wasserman L.H. , Bradley A. , Nelan E. , Story D. , Whipple A.L. 
Published: July 2016

AbstractAfter briefly describing the operation of the Hubble Space Telescope Fine Guidance Sensors (HST–FGS) in the Transfer Function (TF) Scan mode, we discuss the reduction and analysis of scan data affected by HST jitter and Optical Field Angle Distortion (OFAD). We present relative positions and magnitude differences for the components of ADS 11300 = Hu 581 = WDS 18229+1458 derived from TF scans obtained on 17 February 1992. Residuals from a newly revised orbit provide a first indication of the accuracy of HST–FGS observations in the Transfer Function Scan mode.
HIPPARCOS First Results in the Double Star Processing by the FAST Consortium
Authors: Mignard F. , Badiali M. , Bernacca P.L. , Bernstein H. , Cardini D. , Emanuele A. , Falin J.L. , Froeschlé M. , Hering R. , Prezioso G. 
Published: July 2016

AbstractAfter the processing of one year of observations carried out by HIPPARCOS it is possible to provide quantitative results as to the number of new double and multiple stars to be detected and the real capacity of this mission to perform relative astrometry on double stars. We present and discuss the methods developed to this end and include the first results concerning the detection statistics and the determination of separation and position angle for double stars. About 16,000 stars have been recognized as non-single, including 9,000 already known as double and mutliple before the mission. Also, a subset of 10,500 stars have been successfully solved for their relative coordinates with an accuracy in the range of 3 to 10 mas.
Search for Wide Double Stars in the Guide Star Catalog I. All Sky Properties of the Catalog
Authors: Bernacca P.L. , Bucciarelli B. , Lattanzi M.G. , Morbidelli R. , Pannunzio R. , Spagna A. , Sarasso M. , Volpicelli A. 
Published: July 2016

AbstractThe immediate object of this effort is the first systematic investigation of the guide star catalog as a new source list for the discovery of possible new visual binary stars. In this first paper of the series we detail on the way used to establish the properties of the catalog, i.e. techniques adopted to measure its completeness as a function of angular separation, magnitude of the primary, and magnitude differences among the components. We have employed the CCDM catalog as the source list of “certified” visual double and multiple stars. The CCDM stars were first matched (rediscovered) in the Guide Star Catalog and then used to build sufficient statistics to establish the relations among the parameters above. These calibrations are essential to properly correct the two– and three–point angular correlation functions, which are our fundamental tools for establishing lists of new probable visual binary and multiple stars.
Absolute Quadrant Determinations from Speckle Observations of Binary Stars
Authors: Bagnuolo W.G. , Mason B.D. , Barry D.J. , Hartkopf W.I. , McAlister H.A. 
Published: July 2016

AbstractReduction of speckle data obtained for binary stars is typically carried out using power spectrum or, equivalently, autocorrelation methods. An especially powerful algorithm from which accuate differential astronomy can be obtained is the vector autocorrelation technique. While such methods are highly suited to extracting astrometric information from very large volumes of speckle data in near real–time, they inherently introduce a 180° ambiguity in position angle measurement. We briefly summarize results with a new algorithm which maintains most of the simplicity of vector autocorrelation while removing the quadrant ambiguity.
Speckle Observations of Binary Stars with the MAMA Detector
Authors: Horch E. , Morgan J.S. , Giaretta G. , Timothy John G. , Kasle D.B. 
Published: July 2016

AbstractWe have made two sets of speckle observations of binary stars with the Multi-Anode Microchannel Array (MAMA) detector. Our observing system is a true photon counting imaging device which records the arrival time of every detected photon. We present speckle autocorrelation analyses of five binary systems, two observed with the 3.6-m telescope at the European Southern Observatory and three observed with the 40-in reflector at Lick Observatory. These five systems represent a wide variation in separation and magnitude difference that indicate that the MAMA detector is capable of recording high quality speckle data at extremely low count rates and can recover image features very near the diffraction limit of the telescope. In one case, only 10 photons per frame were recorded for the dim companion of the system, and in another case, a separation of 0″.157±0″.031 was derived for a system observed with the 40-in telescope where the diffraction limit is about 0″.125. Future prospects for this system are discussed.
The Homogeneity of the UBV(RI)C System
Authors: Menzies J W 
Published: July 2016

AbstractThere are two large sets of high precision standard star photometry which claim to represent the UBV(RI)c system, one in the E regions in the south established by Cousins and one at the equator due to Landolt. There appear to be systematic differences between them. Astrophysical interpretations which depend on photometric data may in consequence depend on which set of standards was used.
Accuracy in variable star work: The three-star single-channel technique
Authors: Breger Michel 
Published: July 2016

AbstractThe three-star technique for photoelectric photometers is discussed. The technique is used to study millimag variations of variable stars with periods in the range of 30 minutes to a few days. It is emphasized that for highest precision two comparison stars should be used and observed as often as the variable star. The different types of numbers used to express the precision of measurement are discussed together with possible misinterpretations.Finally, the successful use of an extinction coefficient derived from differential extinction between the three stars is illustrated with measurements showing an extreme amount of instrumental sensitivity drift.
An Intimate Relation with Two Automatic Telescopes for Almost Nine Years
Authors: Hall Douglas S. , Henry Gregory W. 
Published: July 2016

AbstractFrom Oct. 1983 through Dec. 1987 most of the observing capacity of the Boyd-Genet prototype 10-inch APT was devoted to a program of 92 variable stars the output of which was sent to us for analysis. From Nov. 1987 through the present the entire observing capacity of the VU-TSU 16-inch APT has been devoted to a program of 136 mostly magnetically active variables. We review the technical performance of both APTs in terms of malfunctions, down-time, resulting photometric accuracy, phase coverage, and scientific results to date.
Dynamics of Type-II Supernovae
Authors: Janka H.-Th. , Müller E. M. 
Published: July 2016

Hydrodynamical simulations of type-II supernovae in one and two dimensions are performed for the revival phase of the delayed shock by neutrino energy deposition. Starting with a post-collapse model of the 1.31 Mʘ iron core of a 15 Mʘ star immediately after the stagnation of the prompt shock about 10 ms after core bounce, the models are followed for several hundred milliseconds with varied neutrino fluxes from the neutrino sphere. The variation of the neutrino luminosities is motivated by the considerable increase of the neutrino emission due to convective processes inside and close to the neutrino sphere (see Janka 1993), which are driven by negative gradients of entropy and electron concentration left behind by the prompt shock (Burrows & Fryxell 1992, Janka & Müller 1992). The size of this luminosity increase remains to be quantitatively analyzed yet and may require multi-dimensional neutrino transport. However, in the presented simulations the region below the neutrino sphere is cut out and replaced by an inner boundary condition, so that the convective zone is only partially included and the neutrino flows are treated as a freely changeable energy source.For small neutrino luminosities the energy transfer to the matter is insufficient to revive the stalled shock. However, there is a sharp transition to successful explosions, when the neutrino luminosities lie above some ‘threshold value’. Once the shock is driven out and the density and temperature of the matter between neutrino sphere and shock start to decrease during the expansion, suitable conditions for further neutrino energy deposition are maintained, and an explosion results. With the neutrino energy deposition the entropy per nucleon in the region between neutrino sphere and shock grows, and convective overturn will set in. Multi-dimensional simulations show that due to the large pressure scale height a large-scale pattern of up-flows and down-flows with velocities close to the local speed of sound develops. Consequently, cold, postshock material is advected down into the neutrino heating layer close to the neutrino sphere and hot material is transported outwards, thus reducing energy losses by re-emission of neutrinos and increasing the pressure behind the shock. Therefore these convective processes are found to be a very important aid to the delayed supernova explosion. In fact, two-dimensional models explode even in cases where spherically symmetrical computations fail.
Detection of Double Stars with the Two-Color Refractometer
Authors: Christy James W. , Wellnitz Dennis D. , Currie Douglas G. 
Published: July 2016

AbstractAttempts to detect double stars are being made with the Two-Color Refractometer (TCR). The refractometer is an instrument developed by the Quantum Electronics Group of the University of Maryland to measure atmospheric refraction.During check-out observations using the U.S. Naval Observatory’s (USNO’s) 24“ reflecting telescope, the refractometer is being used to detect the astrometric separation of the ultraviolet and red photocenters of the combined light from a double star, differentially referenced to nearby stars. The refractometer contains two dispersive wedges which null the incoming dispersion; the positions of the wedges then provide a measure of the dispersion of the incoming light. The angular part of this measure immediately gives the position angle of the double. The angular distance between the two components of the pair is a combined function of the measured quantity and of the magnitude and color differences of the components of the double star, and is therefore obtainable only with additional information.
Review of the Occultation Technique for the Study of Binaries
Authors: White Nathaniel M. 
Published: July 2016

The systematic search for stellar multiplicity by observations of lunar occultations began in 1969. David Evans will review a large portion of the data collected since then in the second paper of this session. Here we will outline the historical development of the technique and comment on its limitations, contributions to double star research, and future improvements.Sir John Herschel (1865) may have been the first to suggest that “a double star, too close to be seen divided with any telescope, may yet be detected to be double by the mode of its disappearance.” However, the visual discovery of duplicity by occultation is not sufficient, for the observations are not subject to analysis after the fact. The power of the occultation technique was realized more than 100 years after the suggestion, with the application of photomultipliers and electronic digital data handling. Whitford (1939) took the first step in using a cesium photo tube, oscilloscope, and moving film to record the occultations of Beta Capricorni and Upsilon Aquarii. The resolution of the spectroscopic binary Beta Capricorni was discussed, but he concluded his data were not able to resolve it, an observation which was later accomplished at several observatories and summarized by Evans and Fekel (1979).
Radial Velocity Observations of Binary Stars
Authors: Scarfe C. D. 
Published: July 2016

AbstractThis review considers three main areas, leaving several others to be discussed in more detail in the contributed papers of this session.1.The need for spectrographs and measuring instruments of great stability for long-term projects such as radial velocity observations of visual binary stars.2.The use of cross-correlation devices, both analog (radial velocity scanners) and digital, for radial velocity measurement.3.The use of comparison spectra impressed directly onto the starlight and of polarisation instruments as means to very precise radial velocities.