bluuebunny/crossref_metadata_2025_split huggingface dataset:
IUE Observations of Long Period Eclipsing Binaries: A Study of Accretion onto Non-Degenerate Stars
Authors: Plavec Mirek J. 
Published: July 2016

It has long been thought that β Lyrae is a unique system, by virtue of its UV spectrum and its nature. I will argue that a whole class of interacting long-period binaries exists, similar to β Lyrae. According to IUE observations made in 1978-79 by myself and R. H. Koch, this group comprises: RX Cas, SX Cas, V 367 Cyg, W Cru, β Lyr, and W Ser. AR Pav is a transition case linking them with the symbiotics. I also suggest that HD 218393 (KX And), HD 72754, and HD 51480 are their non-eclipsing counterparts. I will call the whole group the W Serpentis stars.These systems are mass-transfering binaries (case B) in which the mass transfer rate is relatively high, probably on the order 10−6 to 10−4 M⊙/year. They display an ultraviolet continuum with a color temperature definitely higher than the one observed in the optical region. Even more characteristical is the presence of strong emission lines of N V, C IV, Si IV, Fe III, Al III, and lower ions of C and Si. I will attempt to discuss these phenomena on the assumption that they are due to accretion onto non-degenerate stars.
Computing parallactic refraction for stellar triangulation
Authors: Kakkuri Juhani , Ojanen Ossi 
Published: July 2016

The parallactic refraction correction should be applied to the photographic observations of the light signals carried either by artificial satellites or by meteorological balloons. The correction to the right ascension and declination are made with the equations
where ϕ is the latitude of the observation station, z the zenith distance, α the right ascension, δ the declination and h the hour angle of the light signal. Parallactic refraction is denoted by Δζ.
The direct experimental detection of the systematic error of precise levelling
Authors: Remmer O. 
Published: July 2016

A method is described for determining one and only one parameter governing the refraction effect of levelling. The central idea is that this parameter is determined not by (temperature) measurements during the observation but by adding one more element in the Least Squares Adjustment of the levelling network.Furthermore is described an experiment where it was found that this parameter differed significantly from zero and a tentative first value is suggested.
On the Probability of Collision with Earth, and Orbital Life-Time of Bodies of Asteroidal and Cometary Origin
Authors: Kramer E.N. , Musiy V.I. , Timchenko-Ostroverkhova E.A. , Shestaka I.S. 
Published: July 2016

The radius for gravitational capture of meteoroids by the Earth is
where R is the Earth's radius, h is the height where marked deceleration of meteor bodies begins, α0 is the average distance of the Earth from the Sun, v∞ and vg are preatmospheric and geocentric (undisturbed) velocities of the body.
Planetary Rings
Authors: Cook A. F. 
Published: July 2016

Observations of the Rings of Saturn from the Pioneer spacecraft, discovery of the Ring of Jupiter, ground based polarimetry of the Rings of Saturn and some theoretical studies may be combined to markedly advance our understanding of the Rings of Jupiter, Saturn and Uranus. In particular, narrow rings can be self-gravitatingly stable inside Roche's limit and outside another closer limit. They can be created from a satellite which evolves across its Roche limit either by inward tidal drift or by growth of the planet by accretion.These considerations suggest that Neptune may well be surrounded by one or more narrow rings like those of Uranus.
Radio Observations of Coronal Holes
Authors: Sheridan K. V. , Dulk G. A. 
Published: July 2016

Coronal holes have been observed on several occasions with the 80 and 160 MHz radioheliograph at Culgoora. At 160 MHz the holes invariably appear as areas of low brightness, either on the disk or at the limb. At 80 MHz holes on the limb always appear less bright than their surroundings but on the disk they frequently appear brighter.The simplest interpretation is that the coronal temperature in holes near the 80 MHz critical density (8 × 107 cm−3) is higher than in normal quiet regions, but that the density at this level is lower.
Recent Developments in Improving Daytime Angular Resolution from the Ground
Authors: Kiepenheuer K. O. 
Published: July 2016

The subject of this symposium is the fine structure of the solar chromosphere. Progress in this field of reserach will depend to a high degree of the quality of seeing, resp. on the effective angular resolution available on the ground. Today's situation of solar ground seeing has changed distinctly in the last years. I would like to report here a few new aspects, which could be condensed into 3 questions:
(1)Are there on the ground ‘good seeing windows’, comparable in quality with stratosphere results obtained from balloon borne equipment?(2)Is there a chance to resolve from the ground the solar scale height, corresponding to about 0.1″.(3)Is there a residual fundamental atmospheric seeing noise resp. a basic limit to the atmospheric Modulation Transfer Function (MTF)?
Accuracy Estimation of Astronomical Constants from Long Baseline Interferometer Observations
Authors: Walter H. G. 
Published: July 2016

Inherent in Very Long Baseline Interferometry (VLBI) is the potentiality of determining relative angular positions of radio sources to an accuracy which is superior to present methods by at least one order of magnitude. For VLBI observations such as time delay, fringe frequency and fringe phase the sensitivity to the uncertainties of astronomical constants and geophysical parameters, i.e. luni-solar precession, nutation constant, rate of change of obliquity, polar motion and Earth rotation, is investigated.The partial derivatives of the observations with respect to these unknowns form the core of the estimation process and give evidence of the influence of the source position and the baseline geometry on their magnitudes. By means of a variance-covariance analysis the standard deviations and the cross correlation coefficients of the unknowns are derived. It is inferred from them that VLBI observations are not only sensitive to variations in the astronomical constants and geophysical parameters, but that the effects caused by these variations are also measurable and separable, if the observations are extended over a sufficiently long interval of time, and the baselines and source positions are chosen appropriately.
The Palomar Proper Motion Survey
Authors: Luyten W. J. 
Published: July 2016

The present state of the Palomar Proper Motion Survey is described. Before the CDC automated-computerized plate scanner became operational in 1972, 153 plate pairs had been blinked, whereas since then 443 pairs have been machine processed. Of the remaining 350 fields, some 40 are probably beyond the capability of the present system due to excessive star density.Some 21000 new motions larger than 0″.18 annually have been published. The accuracy of an individual motion is about ± 0″.016 from a single machine-processed plate pair, as compared with ± 0″.025 from hand measured plates.There is an indication that the number of large motions per unit area increases with galactic latitude.
Proper Motions with respect to Galaxies (Invited Paper)
Authors: Deutsch A. N. , Klemola A. R. 
Published: July 2016

At Lick the second phase of the proper motion program is in progress. In addition to generally selected stars, as was done for the first phase, so far over 30000 stars of special types of astro-physical interest and about 29000 AGK3 stars have been selected for measurement.In accordance with the Pulkovo program, second-epoch photography with galaxies is being continued at Pulkovo, Moscow and Tashkent, and proper motions with reference to galaxies are derived.Analyses of proper motions at Pulkovo and Lick show agreement in some instances and disagreement in others. The same applies to comparisons with fundamental catalogues. The analyses suffer to some extent from absence of proper motions in the zone of avoidance and in the southern part of the sky.In the southern hemisphere, first-epoch photography of 164 fields with galaxies has been completed using the Maksutov double-meniscus telescope at Cerro El Roble in Chile, and a complete coverage of the sky has been started with the same telescope; this work is being done jointly by the Soviet and Chilean astronomers. On the Yale-Columbia southern program, the first-epoch photography is nearly completed with the double astrograph at Leoncito in Argentina. There are plans at Lohrmann Institute, Dresden, to take photographs with the 2-m Schmidt telescope at Tautenburg, thus providing first-epoch plates for proper motions with reference to galaxies.
Astrometry with the Large Space Telescope
Authors: van Altena W. F. , Franz O. G. , Fredrick L. W. 
Published: July 2016

The Large Space Telescope (LST), planned to be launched in 1980, will give an opportunity for astrometric observations of high quality to be secured.A detailed survey is presented of the potentialities of the LST for studies of proper motions, parallaxes, star clusters, double stars, perturbed motion stars, occultations, fundamental astrometry and solar system observations.The proposed characteristics and design capabilities of the LST are tabulated.
Influence of the Dynamical Figure of the Moon on Its Rotational-Translational Motion
Authors: Eroshkin G. I. 
Published: July 2016

The influence of the dynamical figure of the Moon on its rotation with respect to its mass centre (the physical libration) is determined by means of the theorem on the angular moment of a rigid body. In the expansion of the Moon's force function in spherical harmonics all the second and the third order harmonics are taken into consideration. For the determination of the Moon's physical libration components a linear system of differential equations of the second order with constant coefficients is constructed.The integration displays the essential influence of the new terms in the force function expansion. For evaluation of the disturbed elements of the lunar orbit due to the nonsphericity of the Moon's dynamical figure the Lagrange's equations are solved. The disturbing function is taken in an expansion form in powers of the eccentricity of the lunar orbit and of the inclinations of the Moon's equator and its orbit with respect to the ecliptic. The commensurability of the Moon's mean motion and its angular velocity of rotation produces in the major semi-axis of the lunar orbit secular perturbations of the first order.
Holes in the Solar Corona
Authors: Glencross W. M. 
Published: July 2016

SummaryBabcock (1961) outlined the sequence of events which takes place in the Sun's atmosphere during a solar cycle. Magnetic field loops, having preferred directions, emerge from the solar surface and thereafter merge with neighbouring loops to produce more extended structures. Although flux tubes emerge with a strong E-W field component, having the field direction reversed from one side of the equator to the other, there is a tendency for the longer loops produced by merging to have a significant N-S alignment (Hansen et al., 1972).
Association of X-Ray Flares with Solar Coronal Active Regions
Authors: Sengupta P. R. 
Published: July 2016

SummaryIt is known that the flare component of solar X-ray emission is sensitive to the level of solar activity. The location of the X-ray flaring region is not directly known but can be inferred from the location of the associated Hα flare. A detailed study of more than 4000 solar X-ray flares recorded by UI and the NRL detectors during past eight years has shown that 85% of these flares definitely occurred in the active regions. For the rest 15% no definite conclusion was possible because either Hα flare data was not available or no Hα flare was reported within ± 15 min of these X-ray flares.
Thermal and Nonthermal Interpretations of Flare X-Ray Bursts
Authors: Kahler S. 
Published: July 2016

Various authors have presented arguments for either the thermal or the nonthermal interpretations of impulsive E > 20 KeV X-ray bursts and slowly varying E < 10 keV X-ray bursts. In this review the arguments for and against the prevailing opinion that the impulsive bursts are nonthermal and the slowly varying bursts are thermal are presented.For the impulsive bursts we discuss the spectra, electron mean free paths, center-to-limb distributions of both the numbers of events and spectra of events, and polarization data as relevant criteria. For the slowly varying events we discuss electron self collision times, distribution of X-ray temporal parameters, associated gradual rise and fall radio bursts, spectral and time profiles of special events and center-to-limb distributions of numbers of events as the relevant criteria.
Ammonia Observations of Dark Clouds Containing Herbig-Haro Objects
Authors: Ho Paul T.P. , Barrett Alan H. 
Published: July 2016

AbstractA study in NH3 was conducted towards H-H objects. Cloud fragmentation appears to have occurred in the regions mapped. Rotation is present with velocity gradients of 1-2 km s−1 pc−1. We suggest that in the regions containing H-H objects, formation of stars of different spectral types may be taking place.
Interstellar Line Spectra of a Dense Cloud: The VI Cygni Association
Authors: Souza Steven P. , Lutz Barry L. 
Published: July 2016

AbstractSpectroscopic observations of the dense interstellar cloud which obscures the VI Cygni association have yielded an optical map of the atomic and molecular constituents in a region which may represent a transition between the diffuse and radio clouds. The velocity of the optical components found is consistent with that of a CO cloud seen in front of No. 12.
Formation of the Giant Planets
Authors: Mizuno Hiroshi 
Published: July 2016

The structure of a gaseous envelope surrounding a icy/rocky core is studied in consideration of radiative transfer. It is found that when the core grows beyond a critical core mass, the envelope cannot be in equilibrium and collapses onto the core to form a proto-giant planet. The results are as follows (for details, see Mizuno 1980).1) The critical core mass is smaller than that estimated by Perri and Cameron (1974) and Mizuno, Nakazawa and Hayashi (1978). 2) When the grain opacity in the envelope varies from 0 to 1 cm2/g, the critical core mass changes from ~2 to ~12 Earth's masses. 3) The critical core mass is independent of the region in the solar nebula.These are due to the existence of the radiative region in the envelope.
GLOBULES, DARK CLOUDS, AND LOW MASS PRE-MAIN SEQUENCE STARS
Authors: Hyland A. R. 
Published: July 2016

The current observational and theoretical literature on Bok globules and their relationship to star formation is reviewed. Recent observations of globules at optical, infrared, and far infrared wavelengths are shown to provide important constraints on their structure and evolutionary status, and the suggestion that many globules are gravitationally unstable is seriously questioned.Dark clouds associated with T associations are well-known sites of recent and continuing star formation. In recent years molecular observations and far infrared surveys have provided maps of such regions from which possible sites of star formation may be identified. Optical (Hα) and near infrared surveys have enabled a clear identification of pre-main sequence (PMS) objects within the clouds. Methods of distinguishing these from background objects and the nature of their infrared excesses are examined in the light of recent observations in the near and far infrared. The perennial question as to the existence of anomalous reddening within dark clouds is also investigated.
Arcsecond Scale Polarization of BL Lac Objects
Authors: Stanghellini C. , Cassaro P. , Bondi M. , Dallacasa D. , Ceca R. Della , Zappalà R. A. 
Published: July 2016

BL Lac objects are an enigmatic class of active galactic nuclei. They are characterized by high luminosity, a flat radio spectrum that steepens at higher energies, relatively high optical and radio polarization, rapid variability and an optical continuum with weak or absent emission lines (see Urry and Padovani, 1995 for a recent review).These properties have been interpreted in terms of a relativistic jet closely aligned to the line of sight (Blandford and Rees, 1978, Ghisellini et al., 1993). This model, known as the beaming model, implies that there must be a so called “parent population” of radio sources intrinsically identical to BL Lac objects, but with the jets oriented at large angles to the line of sight. Browne (1983) was the first to propose the low luminosity FR I radio galaxies as the most likely candidates for the “parent population” of the core dominated BL Lac objects. An outcome of the beaming model is that all the properties not depending on orientation should be shared by the BL Lac objects and the FR I radio galaxies.
Cooling-Flow Models of the X-Ray Emission and Temperature Profiles of Elliptical Galaxies
Authors: Bertin Giuseppe , Toniazzo Thomas 
Published: July 2016

We compare the results of a spherical, steady-state cooling-flow model with gas loss with the observed X-ray emission profiles and temperatures for five bright elliptical galaxies in Virgo and Fornax. We adopt a “thermal-instability” mass-loss prescription (following Sarazin & Ashe 1989) and refer to galaxy models constrained by radially extended stellar dynamical data (Saglia et al. 1992). Our cooling-flow models are specified by three free parameters: the mass accretion rate and the pressure pext at some external radius rext, and a dimensionless constant q, which regulates the mass deposition rate along the flow. We find that models with confining pressures of pext ≃ 4 ÷ 14 × 103K cm–3 and significant accretion rates of external material, up to 4M⊙/yr, provide emission and temperature profiles in good agreement with present-day data. The trend shown in the right frame of the lower panel in the Figure suggests a possible correlation between LX/LB and the iron abundance in the gas inside ellipticals. A full account of this work, together with all the relevant references, is given in Bertin & Toniazzo (1995); here below, we add a comparison of the models with some recent ASCA data (Loewenstein et al. 1994; Mushotzky et al. 1994).This work was partially supported by ASI (under contract 94RS94-202/3 FAE) of Italy.
A new opacity-sampling model atmosphere program for arbitrary abundances
Authors: Kurucz Robert L. 
Published: July 2016

I have developed a new opacity-sampling version of my model atmosphere program called ATLAS12. It recognizes more than 1000 atomic and molecular species, each in up to 10 isotopic forms. It can treat all ions of the elements up through Zn and the first 5 ions of heavier elements up through Es. The elemental and isotopic abundances are treated as variables with depth. At present ATLAS12 reads atomic line data from Kurucz CD-ROM 1 and diatomic molecular data from Kurucz CD-ROM 15. For each line the wavelength, identification, lower energy level, gf, radiative, Stark, and van der Waals damping constants are packed into 16 bytes. At each wavelength point in a frequency integration the Voigt profiles of all the significant nearby lines are computed and summed. The H, He, and auto-ionizing lines are treated with the appropriate profile functions.The fluxes predicted by ATLAS12 are not accurate in intermediate or narrow bandpass intervals because the sample size is too small. A special stripped version of the spectrum synthesis program SYNTHE is used to generate the surface flux for the converged model using the line data on CD-ROMs 1 and 15. That high resolution spectrum can be used directly or can be instrumentally broadened to compare to low resolution observations.ATLAS12 can be used to produce improved models for Am and Ap stars. It should be very useful for investigating diffusion effects in atmospheres. It can be used to model exciting stars for H II regions with abundances consistent with those of the H II region. These programs and line files will be distributed on CD-ROMs.
Modified Method of Krejnin and Murri for the Determination of Absolute Declinations
Authors: Tolchelnikova-Murri S.A. 
Published: July 2016

Krejnin and Muni's method (1973) enablesenables one to derive absolute declinations of stars in a narrow equatorial zone |δ| < 10′ from observations near the Earth's equator |ϕ| < 10′. Some systematic effects, including the errors of the value of the micrometer screw for two equatorial instruments (or the scale error if one of the instruments is a PZT), might be determined if a global reduction is used for the original observations from the equator and from those of an astrolabe at latitude |ϕ| ∼ 20° to 23°. Astrolabes—especially photoelectric ones (Hu 1988) are considered to be the most efficient for determination of absolute declinations of stars and absolute latitudes of the instruments in Tolchel'nikova-Murri (1985).In Izv. GAO No. 206 the method will be published as well as the criterion for estimating the efficiency of different programs, which is required to improve planning in astrometry.
The Celestial System of the International Earth Rotation Service
Authors: Arias E.F. , Feissel M. 
Published: July 2016

The celestial system of the International Earth Rotation Service (IERS) is materialized by the J2000.0 positions of more than 250 extragalactic compact radio sources observed by VLBI. The source coordinates are evaluated from the combination of individual celestial frames obtained by the Goddard Space Flight Center, the Jet Propulsion Laboratory and the U.S. National Geodetic Survey.The combination model and the maintenance algorithm are described. To free the IERS celestial frame from inconsistencies due to the inaccuracy of the IAU conventional models for precession and nutation, it is implemented on individual frames which have been obtained in parallel to the adjustment of corrections to the direction of the celestial pole.The IERS celestial reference frame is consistent with FK5 at a few milliarcsecond level. To be made denser and more accessible for astronomical uses, it will be related to the HIPPARCOS stellar frame.
The Program Complex “Kiev — Geodynamic R1”
Authors: Medvedsky M. M. 
Published: July 2016

The software for the reduction of the VLBI observations of the Main Astronomical Observatory of the Ukrainian Academy of Science is described.Our program complex has three parts:1) calculation of geometrical delay τ,2) calculation of required corrections to values of τ,3) data analysis procedures.This software has been tested using the NGS VLBI data for the obtaining of corrections to the ERP. The parameters of the clock were derived. Our results were compared with similar results, which were published by Shanghai observatory (China) and IRIS bulletin.The differences between our results and the data given in the IRIS bulletin are within 5 mas, and for UT are within 0.1 ms.
Correction to Absolute Proper Motion Using the IAS-Galaxy Model
Authors: Ratnatunga Kavan U. 
Published: July 2016

The IAS-Galaxy model (Ratnatunga, Bahcall and Casertano 1989) is a software interface between theoretical models of the Galaxy and observed kinematic distributions. It has been developed for analysis of many kinematic catalogs to study global galactic structure. In addition, the IASG model can be used to estimate corrections needed to derive absolute parallax and absolute proper motion by evaluating, on a star-by-star basis, the expected mean motion of the reference stars.A theoretical Galaxy model is defined on an inertial coordinate frame. Proper motions are measured in a reference frame defined by a fundamental catalog. The observed distribution of proper motions in star catalogs can be directly compared with the expected distributions evaluated using IASG to check the accuracy of the adopted reference frame in realizing the inertial coordinate frame in the sky.