bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Body Capture in Large N Body Systems
Authors: Giersz M.
Published: June 2019

I have considered the rates of formation of binaries in the following processes: two-body tidal encounters, three-body encounters, self-hardening of soft binaries formed in three-body encounters and two-body encounters connected with gravitational wave radiation. I have considered also the cooling and the heating connected with formation of binaries and the subsequent interactions of binaries with single stars. I have found that the rate of formation of heating binaries in two-body tidal encounters differs from that calculated by Ozernoy and Dokuchaev (1982). These differences are connected first of all with the precise calculation of the dissipated energy of two stars passing near-by each other, maximum and minimum binary binding energy and also with the use of the incomplete gamma function instead of gamma function. The processes presently predominat in the globular cluster conditions are the formation of hard binaries in two-body tidal encounters between evolved and unevolved stars and cooling connected with collisions between white dwarfs and main sequence stars and between white dwarfs. In the systems of density greater than 109pc−3 the binaries formed in three-body encounters (and to a smaller extent self-hardening of soft binaries formed in three-body encounters) predominate the globular cluster evolution. In the globular cluster heating by hard binaries exceedes cooling associated with the tidal interactions and collisions of stars.
Proper Motion Studies of Stars in and Around Open Clusters
Authors: van Leeuwen Floor
Published: June 2019

A compilation of proper motion studies of stars in and around open clusters is presented. It can serve as a reference to cluster member selections, studies of cluster dynamics or as a guide to further improvement of the data presently available. The present paper is only a preliminary version; it is hoped for that reactions from the astronomical community will lead to a more complete and correct study in the near future.
Polynomial expansion of the planetary secular terms: relativistic and lunar perturbations.
Authors: Laskar Jacques
Published: June 2019

The relativistic and lunar perturbations must be included in a realistic theory of the secular evolution of the planetary elements. In our general theory, we include the first order of these perturbations. Comparison with more elaborated studies shows that it is sufficient with respect to the accuracy of our theory.
The precision of modern theories of Galilean satellites as derived with their comparison with photographic observations made with the 26″ refractor at Pulkovo Observatory
Authors: Kisseleva T. P. , Glebova N. I. , Malkova A. G.
Published: June 2019

The regular photographic observations of Galilean satellites has been made with 26″ refractor at Pulkovo since 1975. The relative positions of satellites are obtained by means of “scaletrail” technique. During 1975–1979 over 600 observations of Galilean satellites were carried out. The observed positions were compared with the ephemeris based on Sampson's and Lieske's E-1 theories, the corresponding computations being made at the Institute for Theoretical Astronomy. The standard deviations of one observed relative position “Satellite minus Jupiter” don't exceed ±0″.10. The comparison of Sampson's theory with observations showed some systematic error which can be considered as an error in longitude of about 1 min. Lieske's theory E-1 showed a better agreement with the observations, the absolute deviations not exceeding 0″.3.

A construction of highly precision theories of motion of planet's satellites and of Galilean satellites, in particular, demands appropriately accurate observations (the error not exceeding 0″.10). At present such observations of satellites can be obtained with the help of long-foci telescopes (focal length of about 10 m), using rigorous technique of astrometric reduction.
Coordinate systems in the general relativistic framework
Authors: Fukushima T. , Fujimoto M.-K , Kinoshita H. , Aoki S.
Published: June 2019

The treatment of the coordinate systems is briefly reviewed in the Newtonian mechanics, in the special theory of relativity, and in the general relativistic theory, respectively. Some reference frames and coordinate systems proposed within the general relativistic framework are introduced. With use of the ideas on which these coordinate systems are based, the proper reference frame comoving with a system of mass-points is defined as a general relativistic extension of the relative coordinate system in the Newtonian mechanics. The coordinate transformation connecting this and the background coordinate systems is presented explicitly in the post-Newtonian formalism. The conversion formulas of some physical quantities caused by this coordirate transformation are discussed. The concept of the rotating coordinate system is reexamined within the relativistic framework. A modification of the introduced proper reference frame is proposed as the basic coordinate system in the astrometry. The relation between the solar system barycentric coordinate system and the terrestrial coordinate system is given explicitly.
A formal approach to stellar positions in solar barycentric coordinates
Authors: Lestrade J.F.
Published: June 2019

In astrometry, construction of stellar catalogues favors solar barycentric coordinates. Classically, they are calculated by linearly removing stellar aberration and annual parallaxes from measured quantities yielded by Earth-bound instruments. A global approach is proposed to account for those two effects from a more general relativistic point of view. Implications for VLBI measurements and HIPPARCOS measurements of stellar positions are discussed.
Local frames
Authors: Bertotti B.
Published: June 2019

Following some work by N. Ashby and myself, it is shown how the Fermi construction of local inertial frames can be generalized, in the slow motion approximation, to the neighbourhood of the earth. This allows a clear and simple description of the relativistic effects for the motion of an earth satellite. A proposal by I. Ciufolini to measure the relativistic precession is reviewed.
Relativity effects in the rotation of the Earth and the motion of atmospheric masses
Authors: Shkodrov V. G. , Ivanova V. G.
Published: June 2019

On the basis of observational data on atmospheric pressure (1963–1967), the variation of the moment of inertia, and, with certain restrictions, the changes in the angular velocity of the Earth are obtained. The numerical results derived are compared to the relativity effects in Earth rotation. The comparison shows that both effects are equal in periods and very close in amplitudes.
Relativistic effects from planetary and lunar observations of the XVIII–XX centuries
Authors: Krasinsky G. A. , Aleshkina E. Yu. , Pitjeva E. V. , Sveshnikov M. L.
Published: June 2019

Lunar and planetary observations of different types are discussed for the time span 1717–1982. The modern ranging observations and the historical ones (mainly transits of Mercury and Venus, solar eclipses and occultations of the inner planets by the Moon) are treated separately and some attempts to detect relativistic effects are carried out. From time delay observations linear combination ν = (2 + 2 γ-β) /3 of the parameters of the PPN formalism is evaluated: ν =0.997±0.003. Statistically significant estimate for the rate Ġ of changing of the gravitational constant G is found: Ġ/G=(4±0.8) · 10−11 /yr. (An alternative interpretation of this result due to Canuto et al. (1979) gives negative sign for Ġ). From transits of Mercury and Venus corrections to the adopted system of differences between the ephemeris (dynamic) and the atomic time scales and a correction to the Mercury's perihelion advance are deduced. With new ephemeris time scale it became possible to determine unambigiously lunar tidal deceleration ṅM making use of the historical lunar observations. The derived value ṅM = (−22.2 ± 0.8)′′/cy2 is in good agreement with reported lunar laser results. By comparing the estimates ṅM obtained by the two methods the rate Ġ has also been evaluated: Ġ/G=(0.5+0.5)·10−11/yr. The origin of the disagreement with the radar based result for Ġ is not yet clear. All the conclusions were checked by making use of different planetary and lunar theories and appear to be practically theory-independent.
The Sun's gravitational quadrupole moment inferred from the fine structure of the acoustic and gravity normal mode spectra of the Sun
Authors: Hill H. A. , Rabaey G. R. , Rosenwald R. D.
Published: June 2019

The fine structure of the acoustic and gravity mode multiplets of the Sun have been analyzed to infer the internal rotation of the Sun and upper limits of the internal magnetic field. Observed fine structure for 137 multiplets has been obtained (Hill 1984b, 1985a, 1985b) and the fine structure has been examined for dependence on the angular order, m, of the modes. The inferred angular velocity distribution, together with the estimated upper limits on the internal magnetic fields, yields a gravitational quadrupole moment, J2, of ≈7.7 × 10−6. This result is consistent with the result obtained by Hill, Bos and Goode (1982) and has important implications for planetary tests of theories of gravitation.
Gravitational time delay of signals in the Kerr metric
Authors: Dymnikova I. G.
Published: June 2019

The gravitational time delay of signals in a gravitational field of a rotating massive body is considered both in a weak field approximation and in a strong field caused by a rotating black hole. The expressions describing the time of propagation of signals are obtained by integrating the light geodesics of the Kerr metric in a frame reference of a distant observer using the Boyer-Lindquist coordinates and assuming that the wave length of radiation is much less than the characteristic scale of the field. The existence of the asymmetry in the time delay is shown depending on the mutual orientation of a photon propagation direction and of the rotation axis. As a result of this asymmetry, the effects of relative time delay are predicted and calculated for the signals focused by a rotating gravitational lens.
Extreme M Dwarfs and Brown Dwarfs in a Deep CCD Survey
Authors: Chikotas Boeshaar P. , Tyson J. A. , Seitzer P.
Published: June 2019

Two years ago, Seitzer and Tyson began a program of 4-meter prime focus CCD observations at CTIO, with the aim to develop techniques for imaging and photometry to the theoretical limit of that telescope and overall 52% efficiency: 26.6 J mag, 26 R mag, 25 I mag. Color-magnitude plots show that the limiting magnitudes for detection are 28 J mag, 27 R mag, and 25.3 I mag. Each of our CCD fields covers about 12 sq. arcmin., with total exposure time about 7000 sec. in each of the three bands (see Boeshaar and Tyson 1985). Processed images are put on a VAX 11/780 and the FOCAS v.3.2 automated detector and classifier is run. In order to determine the probability of detection and photometric errors as a function of magnitude, FOCAS is rerun many times on artificial images made by adding in real star and galaxy images, dimmed many magnitudes, at random locations on the CCD sky frame. Over 2000 objects are detected in every high galactic latitude CCD field, less than 50 of which are classified as stars. Most of the faint galaxies are very blue (due to evolution), making it possible to search for infrared excess stars in the presence of so many galaxies.
The Trouble with Binary Galaxies
Authors: Sharp N. A.
Published: June 2019

The statistical analysis of magnitude and center-of-mass velocity data for binary galaxies will never provide an adequate estimate of the mass within the orbit, and will therefore never furnish useful information about the mass-to-light ratios of galaxies. There are three main reasons. Firstly, it is very difficult to find a sample which is both objectively selected and dynamically isolated, and in those cases with obvious tidal distortions it is not clear which two points of the confused systems can be taken to be the centers of mass. Secondly, there are several different ways to produce a mass estimator from the available data, and it is not clear which estimator corresponds most closely to what is normally thought of as the gravitational mass of the system. Finally, those mass estimates which include it as a variable depend quite strongly on the orbital eccentricity, and any analysis method is necessarily least sensitive to just this parameter. Therefore, variation even within a single estimator is both considerable and only weakly constrained.
Estimating the Masses of Galaxy Groups: Alternatives to the Virial Theorem
Authors: Heisler J. , Tremaine S. , Bahcall J.
Published: June 2019

Group masses are almost always computed using the virial theorem. Bahcall and Tremaine (1981) studied the reliability of mass estimates based on the virial theorem for the case of test particles orbiting a central mass. They found that virial theorem estimates were both inefficient and biased. We have extended the work of Bahcall and Tremaine by exploring alternative mass estimators to the virial theorem for self-gravitating systems.
Mass-to-Light Ratios of Spiral Galaxies
Authors: Patricia Vader J.
Published: June 2019

Mass-to-light ratios M/LH−0.5 and M/LB are plotted against color B-H−0.5 in Fig. 1 for 82 nearby spirals from the catalog of Aaronson et al. (1982, Ap. J. Suppl. 50, 241), with BT magnitudes from the RC2, |b| > 20°, 45° ≤ i ≤ 80°, and HI mass estimates. Total masses and infrared H−0.5 magnitudes are measured within the blue isophotal radii R25 and R25/3 respectively, which depend on galaxy color. This color bias is corrected for by replacing R25 by R'25, the radius a galaxy would have at a standard color B-H−0.5 = 2.17. Stellar masses M* and LHC luminosities within R'25 are obtained by substracting twice the HI mass and by extrapolation, respectively. Corrected ratios M*/LHC and M*/LB versus corrected color B-HC are shown in Fig. 1 together with theoretical model predictions. The corrected observed ratios are systematically larger for bluer galaxies than predicted so that bluer spirals seem to have relatively more massive halos, in agreement with earlier results (Tinsley, B.M. 1981 M.N.R.A.S. 194, 63; Vader, J. P. 1984, in Formation and Evolution of Galaxies and Large Structures in the Universe, eds. J. Audouze and J. T. Thanh Van, p. 227).
Neutrino Mass Limits and Dark Halos
Authors: Madsen Jes , Epstein Richard
Published: June 2019

Lower mass limits for particles constituting the dark matter in galaxy halos can be derived from considerations of the initial and final phase space distribution. In the case of massive neutrinos, Tremaine and Gunn (1979) pointed out that the initial fine-grained occupation number of cosmological neutrinos and therefore the final coarse-grained phase space occupation, is less than 0.5. From this they were able to show that if the final neutrino distribution is an isothermal sphere, one can put lower limits on the neutrino mass from assumptions about the core radius of the neutrino sphere.
Extended X-Ray Emission from Early-Type Galaxies: Comparison with Optical
Authors: Trinchieri G. , Fabbiano G.
Published: June 2019

In this poster we display the results from a detailed analysis of the distribution of the X-ray emission in early type galaxies. Two major results have come out of the analysis so far:

a)

The surface brightness radial profiles of isolated elliptical and SO galaxies are smoothly decreasing functions of radius out to a Rmax (similar to the optical radius). Outside Rmax a flattening in the slope is observed, although the exact shape of the profiles at large radii, where the data are poorest, cannot be determined at present.

b)

For R«Rmax, the X-ray and optical surface brightness profiles are similar (the nuclear region could be an exception). At larger radii, the X-ray profile could be flatter (NGC 4649 and NGC 4472 northern sector) or steeper (NGC 4472 southern sector) than the optical profile, or have a similar shape (NGC 4636).

It is likely that the different profiles reflect the action of slightly different environments and/or a different ambient density around each galaxy, combined with the “history” of each galaxy. The tail in NGC 4472 could be the result of the motion of this galaxy in a dense intracluster medium. The X-ray deficiency in NGC 4649 could be due to either ram pressure stripping or the action of wind in the outer regions of the galaxy.
Gravitational Lenses and Dark Matter: Observations
Authors: Turner Edwin L.
Published: June 2019

Following a few general comments on gravitational lenses from an observer's perspective, the currently available observations of the six known gravitational lenses are summarized. Attention is then called to some regularities and peculiarities of the properties of the known lenses and to how they might be interpreted. The most important conclusions relevant to the dark matter problem which can be obtained from the current observations are that the distributions of mass and light appear to be quite different in at least some of the lensing objects and that objects with projected M/R values about ten times larger than those ordinarily associated with galaxies exist and are not too rare (assuming Λ = 0).
The Modified Newtonian Dynamics as an Alternative to Hidden Matter
Authors: Milgrom Mordehai , Bekenstein Jacob
Published: June 2019

The mass discrepancy, which has led to the notion of dark matter may, in fact, be due to a breakdown of the Newtonian laws which are used to determine the masses of galactic systems. We describe a nonrelativistic theory which departs from Newton's in the limit of small accelerations. When one uses the modified dynamics to deduce gravitational masses, the need to invoke large quantities of dark matter disappears. We outline the theory and give criteria for deciding which systems are expected to exhibit marked departures from Newtonian behaviour. The main body of the talk is a succinct description of the major predictions of the theory regarding dynamics within galaxies.
Cosmological HII Regions
Authors: Shapiro Paul R. , Wasserman Ira , Giroux Mark L.
Published: June 2019

We have generalized the classical description of ionization front propagation to the case of a point source in a uniform, cosmologically expanding gas. We present illustrative curves for the comoving radius and peculiar velocity for several turn-on redshifts, z0N, for Ωtot = 1, Ωb = 0.1, h = 1. The quantity RS is the generalized Strömgren radius [RS = RSi (1 + z0N)/(1 + z), RSi = (3Nu/4πnH,i2 α2)1/3, Nu = photoionizing number flux per source, α2 = recombination rate to n = 2, nH,i = nHo (1 + z0N)3]. The quantity T0N = 2 (1 + z0N)−3/2/(3H0). We also plot ζ, the value of (2nQoNph, Q/3HonHo) needed to ionize the IGM with overlapping QSO HII regions by redshift z0V for QSO turn-on at various z0N, where Nph, Q = ionizing photon luminosity per QSO, nQo = QSO number density (present co-moving value), nH = H density of IGM, and nH/nHo = nQ/nQo = (1 + z)3. From a recent preprint by Koo (1985), we estimate ζ ≲ 1 (for Ωb = 0.1, h = 1) for QSO's with L ∼ 1045 erg s−1. In this case, the observed QSO's cannot be the sole source of the IGM ionization that is implied by the null detection of the Gunn-Peterson effect for QSO's with z > 2.
Background Light from Population III Stars
Authors: McDowell Jonathan C.
Published: June 2019

It has been proposed (e.g. Carr, Bond and Arnett 1984) that the first generation of stars may have been Very Massive Objects (VMOs, of mass above 200 M⊙) which existed at large redshifts and left a large fraction of the mass of the universe in black hole remnants which now provide the dynamical ‘dark matter’. The radiation from these stars would be present today as extragalactic background light. For stars with density parameter Ω* which convert a fraction ϵ of their rest-mass to radiation at a redshift of z, the energy density of background radiation in units of the critical density is ΩR = εΩ* / (1+z). The VMOs would be far-ultraviolet sources with effective temperatures of 105 K. If the radiation is not absorbed, the constraints provided by measurements of background radiation imply (for H =50 km/s/Mpc) that the stars cannot close the universe unless they formed at a redshift of 40 or more. To provide the dark matter (of one-tenth closure density) the optical limits imply that they must have existed at redshifts above 25.
Detecting Cold Dark Matter Candidates
Authors: Drukier A. K. , Freese K. , Spergel D. N.
Published: June 2019

We consider the use of superheated superconducting colloids as detectors of weakly interacting galactic halo candidate particles (e.g. photinos, massive neutrinos, and scalar neutrinos). These low temperature detectors are sensitive to the deposition of a few hundreds of eV's. The recoil of a dark matter particle off of a superheated superconducting grain in the detector causes the grain to make a transition to the normal state. Their low energy threshold makes this class of detectors ideal for detecting massive weakly interacting halo particles.

We discuss realistic models for the detector and for the galactic halo. We show that the expected count rate (≈103 count/day for scalar and massive neutrinos) exceeds the expected background by several orders of magnitude. For photinos, we expect ≈1 count/day, more than 100 times the predicted background rate. We find that if the detector temperature is maintained at 50 mK and the system noise is reduced below 5 × 10−4 flux quanta, particles with mass as low as 2 GeV can be detected. We show that the earth's motion around the Sun can produce a significant annual modulation in the signal.
Unstable Dark Matter and Galaxy Formation
Authors: Suto Yasushi , Kodama Hideo , Sato Katsuhiko
Published: June 2019

Recently cosmology with unstable particles has attracted much attention as a possible solution to several important problems in the present universe. In this scenario, however, nonlinear structures in the universe would not easily form since their binding energy would decrease gradually in the course of the decay of unstable particles. Thus this scenario is stringently constrained by the galaxy formation problem. In order to obtain the constraints quantitatively, we carried out numerical calculations of the evolution of density perturbations after the time of recombination. Universe is assumed to consist of three components; unstable X-particles, its non-radiative decay product (massless particles) and baryons. Initial conditions are specified by the density contrast of X-particles δX,i and the baryon density parameter Ωb,i. Resultant baryon density contrast at Z = 4 (epoch of galaxy formation) and Z = 0 (present) is shown below for Ωb,i = 0.005.
Several Statistical Properties of Galaxies with UV Excess
Authors: Kazarian M.A.
Published: June 2019

The number of galaxies with UV excess relative to normal galaxies is determined and other statistical characteristics of galaxies with UV excess are also presented.

V.A. Ambartsumian's idea of the activity of galaxy nuclei, suggested 30 years ago, has played a great role in the development of extragalactic astronomy. He showed that the evolution of galaxies depended on the activity of their nuclei. According to Ambartsumian (1958) the nuclei of galaxies are active if explosions take place in them. These explosions lead to large radio fluxes and in general to the wide range of phenomena normally associated with nuclear activity.

The spectra of active galaxies show ultraviolet (UV) excess and emission lines of hydrogen and other elements. In other words, the UV excess and emission lines which are observed in the spectra of galaxies are the consequence of active processes.
Blue Objects Near M 31 and Optical Identifications of 5C3 Sources
Authors: Richter G.A.
Published: June 2019

Blinking several pairs of U and B Tautenburg Schmidt plates (area ≈ 90□°) 1131 UV excess objects (B ≲ 21, U-B≲0.0) were found with projected distances R ≳ 15 kpc from the M 31 centre. The objects were investigated by U, B, V, r, i photometry and partly by Tautenburg objective prism plates and by image tube spectrographs (Tautenburg, Zelenchukskaya) with Drs. AFANAS'EV, KOPYLOV, NOTNI, LORENZ.
Extended Infrared Emission in Seyfert Galaxies
Authors: Rodriguez Espinosa J.M. , Rudy R.J.
Published: June 2019

We have analyzed far-IR (IRAS) data for a sample of optically selected Seyfert galaxies. The far-infrared emission is uncorrelated, or at best weakly correlated, with the UV-optical emission from these sources. We find the far-IR emission to be extended in a number of objects. We discuss the possibility that Seyfert galaxies are undergoing circumnuclear bursts of star formation. For comparison with the large aperture IRAS data we have also obtained new ground-based measurements at 10 and 20 μm for a sample of 17 Seyfert galaxies. Conclusive evidence for extended 10 and 20 μm emission is seen in 7 out of 17 objects. In addition, almost all of the objects have ground-based fluxes which are smaller than those measured by IRAS. Finally, for five objects the emission appears to be more extended at 10 μm than at 20 μm. This would be expected if the 10 μm emission arose, in part, from a population of very small grains for which single photon heating is important.
Emission Lines Variations in the Spectra of Seyfert Galaxies Nuclei. Observational Data
Authors: Pronik I.
Published: June 2019

The emission lines variability in the spectra of Seyfert galaxies nuclei has been known for more than 20 years. The first report on the problem under consideration was made by Bardin et al.(1967). They published the data on the variation of relative intensities of forbidden 4959+5007 A and 4363 A [OIII] lines in the spectrum of NGC 5548 galaxy nucleus that exceed the errors of observations. It was noticed also that NGC 5548 was the second galaxy where the considered lines show variability. At least four review papers have been published: Lyutyi and V. Pronik (1975), Collin-Souffrin(1980), I. Pronik (1980), Penston(1982).
A Search for Periodicities in the Light Variation of Some Seyfert Galaxies
Authors: Bisch S.M. , Pastoriza M.G. , Dottori H. , Busko I.
Published: June 2019

Penfold's UBV observations of the Nuclei of the Seyfert galaxies NGC 1566, NGC 3227, NGC 3783, NGC 6814, NGC 7469, Mk 50 and IC 4329A are examined to look for a possible periodicity in the variation of the magnitudes and colors. A method based on the fitting of sinusoidals and the calculation of the multiple correlation coefficient adequated to the analysis of observations unequally spaced in time is used to analyse the data. Four of the seven galaxies studied show a high probability of having periodic component in the variation. Recent UBV observations were used to test the components in two of them.
On the Nature of Processes Occurring in Active Nuclei of Galaxies
Authors: Gorbatsky V.G.
Published: June 2019

An explanation of observed phenomena in AGN is proposed on the basis of the hypothesis about the ejection of compact formations from a “central object” which emits relativistic electrons. In particular, the possible causes of the discrete structure of jets, appearance of “superluminal” velocities and superfast variations of radiation from nuclei in X-ray and optical regions are considered.
The Forest of Absorption Lines in QSO Spectra - A Key to the Large Scale Structure Development?
Authors: Mücket J. P. , Müller V.
Published: June 2019

For six published high resolution QSO spectra a correlation analysis of unidentified absorption lines is performed. The two-point correlation functions typically show some quasiperiodic structure. The results allow for the interpretation that absorbing clouds lie in sheetlike structures as predicted by the pancake theory.
Imaging of Low Redshift PG Quasars and Their Companions
Authors: Yee H.K.C.
Published: June 2019

Images of 16 PQ quasars with z < 0.2 were obtained using the CCD camera at the 2.3 m telescope of Steward Observatory. It is found that about 35% of the quasars have one or more close companions (at r ≤ 100 kpc). The data also suggest that the companion galaxies are almost always redder than the nebulous components of the quasars. This is consistent with previous findings by other investigators that companion galaxies of quasars do not have high level of activity.
1411+442: Optical Imaging of a BAL QSO
Authors: Hutchings J.B.
Published: June 2019

Results are presented of optical imaging of the low redshift BAL QSO 1411+442, in four colours. The host galaxy is revealed as an inclined spiral galaxy with a long arm which may be a tidal tail. There also appears to be connecting luminosity to two nearby objects. There is a straight blue feature emerging from the nucleus and Ha emission from an oppositely directed filament. [O III] appears to be enhanced in some outer regions. While the host galaxy is more exotic than usual for QSOs, it is not obvious how these properties are connected with the BAL phenomenon.
Tight Nuclear Spirals: Observational Evidence of Nuclear Activity
Authors: Pişmiş P. , Moreno E.
Published: June 2019

It is argued that the tightly wound spiral structure in the nuclei of some galaxies -generally referred to as rings- provides evidence of nuclear activity. It is shown that such spirals are the loci of plasma ejected in a bi-polar fashion from the equator of a rotating nucleus and funneled by a magnetic field. The equation of the loci is derived and applied to the nuclear spiral of NGC 4736. The observed rotational and angle-dependent ejection velocities, as well as polarization of non-thermal continua give support to our model.
Star Formation in Galactic Nuclei
Authors: Tutukov A. V.
Published: June 2019

The star formation in galactic open clusters leads, as a rule, to a complete disruption of the latter (Tutukov, 1978) because of the shallow potential wall of these clusters. The matter of dense galactic nuclei is in deep potential walls what drastically changes the star formation regime. The numerical dynamical model of the star formation in galactic nuclei with the mass 6 109 M⊙ and the radius ~ 430pc was proposed by Loose et al (1982). It includes old and newly-formed stars, gas and dust distributed initially as in the center of our Galaxy. The model takes into account the star formation, supernova explosions, stellar winds, the turbulent motion of the gas component, non-grey radiative energy transfer, the influx of gas from old stars and from the outside. The main parameter of our model is the time of dissipation of the kinetic energy of the gas component Td. Supernova explosions are the main source of this energy. The results of numerical experiments help to point out two main regimes of the star formation in galactic nuclei: stationary and bursting. In the stationary regime the rate of the star formation is constant and it equals to the rate of the gas input. The formation of a long-living superstar is possible in this case (Krügel, Tutukov, 198b). In the bursting regime the periods of an active star formation alternate with those of almost a complete absence of the star formation. The main reason for supressing the star formation process is supernova explosions which throw the gas out of the galactic nuclei.
An overview of helio- and asteroseismology
Authors: Christensen-Dalsgaard Jørgen
Published: June 2019

The purpose of the present paper is to give an introduction to the nomenclature, and a few of the results, of helio- and asteroseismology. It is hoped that this may provide a useful background for the more specialized reviews, and the contributed papers, in these proceedings. Other recent, general reviews are, e.g., Deubner & Gough (1984), Leibacher et al (1985), and Christensen-Dalsgaard et al (1985a).
Splitting of the low ℓ solar p modes
Authors: Jefferies S.M. , McLeod C.P. , van der Raay H.B. , Palle P.L. , Cortes T. Roca
Published: June 2019

An analysis of full disc line of sight velocity data yield line splitting values of the low ℓ-value non-radial modes. Possible variations of the line splitting with the solar cycle are investigated.
Response of the solar five-minute oscillations to a major flare
Authors: Haber Deborah A. , Toomre Juri , Hill Frank
Published: June 2019

Solar five-minute oscillations of intermediate-degree ℓ were observed both before and after a very strong white-light flare. Intensity images of the full Sun taken on two sides of the Fe I λ 5576 spectral line were recorded on film, digitized with 8″ spatial resolution, and then converted into Doppler velocities. The data were projected onto both equatorial and polar sectoral modes and Fourier transformed in time. Comparing the resulting power spectra, we find a substantial increase in power in the p5 ridge of the equatorial modes on the day after the flare; such an increase may be a consequence of the solar flare. When data from all the ridges are considered, there is an average increase in power of only a few percent the day after the flare. This overall increase is probably not significant due to uncertainties from effects of the beating of unresolved modes.
Do solar models with weakly interacting massive particles reproduce the Stanford seismic data?
Authors: Ellis A. N. , Gough D. O.
Published: June 2019

The discrepancy between theoretical eigenfrequencies of standard solar models and the frequencies of solar modes of degree between 2 and 5 measured at Stanford is degree-independent for cyclic frequencies above about 2 mHz. Below that frequency the discrepancy for dotriacontapole modes diverges from that of the modes of lower degree. The differences between eigenfrequencies of a simple solar model containing a cloud of weakly interacting particles in its core and of one without do not reproduce this behaviour.
An optimal approach to the inverse problem
Authors: Jeffrey W. , Rosner R.
Published: June 2019

We describe how remote sensing problems can be reformulated within the framework of optimization theory. This reformulation allows any prior knowledge about the solution to be naturally incorporated into the solution process. The inversion problem then reduces to a search for the global extremum in the possible presence of local extrema. Two algorithms are presented that can be used to solve this global optimization problem, and their application to the helioseismology inverse problem is detailed.
Inverse problem: acoustic potential vs acoustic length
Authors: Shibahashi Hiromoto
Published: June 2019

By using the quantization rule based on the WKB asymptotic method, we present an integral equation to infer the form of the acoustic potential of a fixed ℓ as a function of the acoustic length. Since we analyze the acoustic potential itself by taking account of some factors other than the sound velocity and we can analyze the radial modes by this scheme as well as nonradial modes, this method improves the accuracy and effectiveness of the inverse problem to infer the internal structure of the Sun, in particular, the deep interior of the Sun.
The energy conversions and enhancement caused by the unsteady plasma motion in the active region
Authors: Zhongyuan Li
Published: June 2019

In this paper, The author has discussed the coupling processes between the magnetic field and the unsteady plasma motion, and analysed the features of the energy storage and conversions in the active region.
Variations in the mean line of sight velocity of the Sun: 1976–1985
Authors: Jiménez A. , Pallé P.L. , Régulo C. , Cortés T. Roca , Elsworth Y.P. , Isaak G.R. , Jefferies S.M. , McLeod C.P. , New R. , van der Raay H.B.
Published: June 2019

Measurements of the line of sight velocity of the sun with respect to earth have been obtained at Izaña (Tenerife) during the years 1976 to 1985. The mean values found for each year show a trend of ~30 m/s from minimum to maximum. Their mean value is of 583.1 ± .2 m/s which is 92% of the gravitational red shift predicted by theory and their variation seems to be related to the solar cycle with the clear exception of 1985. The most likely interpretation is that the velocity limb shift effect, averaged over the whole sun, is the cause of the slight disagreement with theory and this effect changes with time.
The rich p-mode pulsation spectrum of HD 60435
Authors: Matthews J.M. , Kurtz D.W. , Wehlau W.H.
Published: June 2019

Twelve cool Ap stars are known at present to undergo rapid light oscillations at low amplitude (ΔB < 0m.012) and with periods of minutes. These rapidly oscillating Ap (roAp) stars also exhibit amplitude modulation with timescales of days, which correspond to the magnetic/rotation periods (when those have been measured). In at least one case (HR 3831), 180° phase shifts in the dominant oscillation are seen twice per modulation cycle.
Modeling the global oscillations of Epsilon Eridani
Authors: Soderblom David R. , Däppen Werner
Published: June 2019

We have reviewed the observational data for ∊ Eri to derive our best estimates of luminosity, radius, temperature, composition, and age, as well as the uncertainties associated with each of these. These quantities are then used in stellar structure models to try to reproduce the global oscillation frequencies observed by Noyes et al. We find that we can reproduce the observed frequencies and splittings at least as well as the computations of Guenther and Demarque, yet for significantly different stellar parameters, most notably the age.
Stellar models of ε Eridani constrained by stellar seismology
Authors: Guenther D. B.
Published: June 2019

Because Epsilon Eridani (Z = 0.013) appears about 0.2 mag above the Z = 0.02 zero-age main sequence, zero-age models of Epsilon Eridani must be evolved off the ZAMS to ages much older than its rapid rotation and high chromospheric activity suggests. To resolve this conflict we propose that either Epsilon Eridani is part of a binary system or that its metal content has been underestimated. To test these hypotheses we use not only the stellar constraints of luminosity and effective temperature but also impose that the characteristic frequency spacing of the oscillation spectra of the models match the value observed by Noyes et al. (1984).
Can stellar mass be measured by asteroseismology?
Authors: Ulrich Roger K.
Published: June 2019

Theoretical calculations show that the detailed pattern of frequencies from stellar oscillations can in principal produce data that can determine stellar masses independent of other input data.
Excitation and damping of solar and stellar oscillations
Authors: Chitre S.M.
Published: June 2019

Variable stars can be broadly classified into two categories: (a) High amplitude pulsators like Cepheids and RR Lyrae variables, (b) Low amplitude pulsators like Sun and Sun-like stars. The study of stellar pulsations has opened the possibility of using the oscillatory modes to probe the internal structure and dynamics of these stars. The cause of pulsational instability for a majority of stars is the partial ionisation of the abundant elements present in the envelope of the stars, while some instabilities are driven by the transfer of momentum from the medium to the oscillating elements. Various mechanisms responsible for exciting and limiting the solar and stellar oscillations are discussed.
The role of nuclear reactions in the excitation of stellar oscillations
Authors: Gavryusev V.G. , Gavryuseva E.A.
Published: June 2019

The contribution of each element participating in p-p chain and each region of star to oscillation excitation by nuclear energy is investigated. The gravity modes the most easily excited by this way are indicated.
Interaction of convection and oscillations in the solar atmosphere: numerical results
Authors: Steffen M.
Published: June 2019

Analysing the results of numerical simulations of solar granular convection we found, superimposed on the convective flow, an oscillatory phenomenon with a well defined period of 260 ± 15 sec.
Finally a double-mode RR Lyrae model?
Authors: Buchler J.R. , Kovács G.
Published: June 2019

It is shown that in a certain range of physical parameters a proper choice of the artificial viscosity parameters can lead to double-mode pulsation of RR Lyrae models. Here we present one such model and exhibit its double-mode behavior both through the stability analysis of the periodic limit cycles and through straightforward numerical integrations.
Oscillatory properties of meso-scale intensity structures at chromospheric level
Authors: Dame L. , Martic M.
Published: June 2019

We show the evidence at chromospheric level (Call K line) of mesostructures, “mesocells”, reminiscent of the mesogranulation by their spatial size (8 Mm). These cells present very regular oscillations in intensity, preferably in the 3–5 min. period range, and we show that the phase of the sustaining wave extends smoothly (coherently) over the mesocell area.
The precision calcium photometer: A New Instrument for Astroseismology
Authors: Nisenson P. , Dupree A. K. , Noyes R. W.
Published: June 2019

The Precision CAlcium Photometer (PCAP) has been built with characteristics optimized for amplitude astroseismology. The instrument consists of two units: an on-telescope optical system that forms and stabilizes a stellar image onto a 200 micron optical fiber; and a spectrometer unit that accepts the light from the fiber and integrates the Calcium II H and K lines (3968.5 Å and 3933.7 Å), along with adjacent continuum regions, in a photon-counting mode. Some key system characteristics include active image stabilization, a 12-meter optical fiber with ~70% transmission at 3950 Å, and a thermally and mechanically stable spectrometer. A description of the instrument and of laboratory and on-telescope test runs are discussed below.
Requirements of a network telescope
Authors: Elliott Ian
Published: June 2019

General purpose telescopes fail to provide a cost-effective means of obtaining photometric data for asteroseismology. A continuous observing run on a particular star is best suited to automatic operation with a dedicated photoelectric telescope. As optical requirements for on-axis photometry are less severe than those for imaging, low-cost light-weight mirrors permit a saving in the size and cost of mount and dome. A stiff mounting with a low moment of inertia permits rapid movement under computer control. Adoption of a permanently mounted photometer and the elimination of manual controls also leads to design and operating economies. Maintenance can be shared with other instruments and travel and subsistence requirements are minimised. Therefore remote operation of a network of automatic telescopes at good sites could provide high quality data at reasonable cost.
Prospect for stellar seismology on board an interplanetary spacecraft
Authors: Praderie F. , Mangeney A. , Lemaire Ph. , Puget P. , Bisnovatyi-Kogan G.S.
Published: June 2019

We describe a stellar seismology photometric experiment which we have proposed to embark on-board the interplanetary vehicles belonging to the VESTA mission (France - USSR mission towards Mars and the asteroids belt, to be launched about 1994). The objective is to use the cruise time to obtain long, uninterrupted observations of the white light fluctuations in a few late-type stars, with a view to the detection of global non-radial modes at the level 10−5 to 10−6 mag. We have performed a design-study of the instrumentation, formed by a 5 cm spherical collector, working in two spectral bands 1500 A wide, with two photomultipliers as detectors. Advantages and difficulties of the system are briefly discussed.
An extremely high ‘Q’ueue value applied to seismological meetings
Authors:   Anonymous (perhaps Hunger and Tooth)
Published: June 2019

Recent observations of the mysterious astronomical body IAU 123 indicate that the ‘Q’ueue value for astronomy symposia can approach 100–120, with very rapid growth and slow exponential decay. Number density fluctuations, with a frequency of 11.56 μHz and extreme phase coherence have been detected outside the main cafeteria. The long period and high ‘Q’ suggest that this may be represented by a g-mode of low radial order.

A stabilized Fabry-Perot etalon has been used to measure the low-level motions, with propagation velocities of order 0.01 cm s−1. Although this is well below the local Alfvén speed, there can still arise significant shock effects (e.g. upon discovery of liver loaf as the main course).

The observed cafeteria oscillation spectrum is still incomplete. For instance, if ice cream were offered at the end of the line, we would expect to detect the well-known ‘a la’-mode predicted by Baskin and Robbins.

We hope that future studies of astronomical Q's may lead to a better understanding of solar-type astronomers' resonant cavities.
CCD Spectrophotometry of Planetary Nebulae at Wendelstein Observatory
Authors: Roth M. M. , Kudritzki R.-P. , Méndez R. H.
Published: June 2019

During the past decade the achievements in the theory of stellar atmospheres of hot stars combined with improved spectrograph and detector technology at large telescopes have led to a significantly improved knowledge of PN nuclei properties (see Méndez et al. 1988, Kudritzki and Méndez 1989).
Mass Loss in Two Low Temperature Central Stars of Planetary Nebulae
Authors: Modigliani A. , Perinotto M. , Patriarchi P.
Published: June 2019

The high resolution IUE images SWP 16742 and SWP 42675 have been studied to derive the fast wind properties of the central stars of the two low temperature planetary nebulae IC 2149 and Tc 1. The first image is from the IUE archive, while the second one has been taken by us.
Interstellar Extinction of Planetary Nebulae
Authors: Stasinska G. , Tylenda R. , Acker A. , Stenholm B.
Published: June 2019

We have compared the extinction of planetary nebulae (PN) as derived from the Balmer decrement and from the ratio of radio to Hβ fluxes.
Filling Factors and Ionized Masses of Planetary Nebulae
Authors: Boffi Francesca R. , Stanghellini Letizia
Published: June 2019

We present a study on the filling factors and ionized masses of four sets of galactic and extra–galactic planetary nebulae (PNe) at known distances. The calculation of filling factors and ionized masses has been pursued as to get a deeper insight on the evolution of this class of objects. We used a galactic set of PNe, another set of nebulae that are averagely located near the galactic center, and two sets of nebulae in the Magellanic Clouds. As input data, we used the electron densities derived from the forbidden line intensity ratios, the Hβ nebular fluxes, the distances of galactic PNe derived from extinction, and the distances of galactic center PNe and of extra–galactic PNe derived from galaxy (or galactic region) memberships. All these quantities, plus the input angular radii, have been selected among the most recent measurements available in the literature. We obtained several interesting results. (1) The calculated filling factors are on average much smaller than what is usually assumed, independently for each set. (2) The ionized masses are all in good agreement with the theoretical predictions, with the possible exception of the Galactic Bulge PNe. (3) Both filling factors and ionized masses cover a wide range of values as it is shown in the cumulative histograms below (filled circles=local PNe; open circles=galactic center PNe; filled squares=LMC PNe; open squares=SMC PNe).