bluuebunny/crossref_metadata_2025 huggingface dataset:
The OAO-B Telescope
Authors: Boggess Iii A.
Published: July 2016

The third Orbiting Astronomical Observatory will be launched in the Fall of 1970 carrying a 92 cm telescope and a scanning spectrometer. The instrument can produce stellar spectra in the range from 1000 to 4000 Å at resolutions of 2, 8 or 64 Å. Several entrance apertures can be used, including a 5′ × 6′ slot, a 1′ circle and two narrow slits for special conditions. The spectrometer employs six pulse counting detectors spaced at 500 Å intervals, and can also be used as a fixed wavelength six channel photometer for faint objects. The detection and data handling systems are designed to yield photometric data at a constant statistical precision of 1.6% with a maximum integration time of 42 s at each wavelength.
Attempts to Observe the Absolute Intensity and the Centre-to-Limb Variations of the Sun in the Vacuum Ultraviolet Region
Authors: Nishi K. , Suemoto Z.
Published: July 2016

Calibration for two rocket-borne spectrometers to observe the absolute intensity and the centre-to-limb variations of the Sun between 1500 Å and 2000 Å is described. The procedure of the calibration is divided into two parts, (a) the measurements of the transmission of the spectrometers, and (b) the absolute detector calibration.

The double dispersive spectrometer has been planned to be launched in September 1970, but it was postponed until the coming winter, and the single dispersive spectrometer will be launched in January 1971.
The irregular rotation of the earth
Authors: van der Waerden B. L.
Published: July 2016

A mechanical explanation of the observed irregular rotation of the surface of the earth is proposed. From this probabilistic model the correlations between the apparent fluctuations of the motion of the moon in successive years are derived and a modified least-square method is developed for finding the secular accelerations of sun and moon.
Variation progressive et variation saisonnière de la rotation de la Terre
Authors: Danjon A.
Published: July 2016

Exposé préliminaire des résultats de la comparaison du temps universel déduit des observations faites à l'astrolabe impersonnel de l'Observatoire de Paris, et du temps uniforme fourni par l'étalon à césium de L. Essen et J. V. L. Parry.
The influence of systematic errors of star catalogues on the determination of the irregularities of the earth's rotation
Authors: Nemiro A. A. , Pavlov N. N.
Published: July 2016

In order to lessen the influence of the errors in the right ascensions of stars of fundamental systems on the results of time determinations, it is proposed that the results of time services observing with transit instruments be used for the determination of an independent system of right ascensions of stars. The participation in this work by a maximum number of observatories of different countries is desirable.
Ephemeris time
Authors: Clemence G. M.
Published: July 2016

In this article is described the measurement of time from a more general point of view than has been taken before. It is shown that mean solar time and ephemeris time are two particular applications of the general principle of measuring time by observing angular motions, a principle that can be applied to any angular motion whatever, provided that an adequate theory of the motion is available.
The constant of nutation and the system of astronomical constants
Authors: Vicente R. O.
Published: July 2016

The author discusses the dependence of the constants of nutation and precession upon the values of other fundamental constants such as the dynamical ellipticity of the Earth, the mass of the Moon and the solar parallax in the case of two different theoretical models of the Earth.
La constante de l'aberration en astrométrie
Authors: Guinot Bernard
Published: July 2016

The author discusses the effects of the error in the conventional value of the constant of aberration upon the precision of modern observations for time and latitude. He proposes 20″.50 as a new conventional value for k, suggesting that the change should be made as soon as possible.
An attempt to reconcile the dynamical and radar determinations of the Astronomical Unit
Authors: Marsden B. G.
Published: July 2016

It has been found possible to obtain a solution which satisfies both the dynamical and radar investigations without doing any great injustice to any of the observations. It is deduced that the astronomical unit is determined more satisfactorily from the radar bounces off Venus rather than by dynamical methods alone. Some comments are also given concerning the masses of Mercury, Venus and Mars.
Some remarks on the paper by B. G. Marsden “An attempt to reconcile the dynamical and radar determinations of the Astronomical Unit”
Authors: Rabe Eugene
Published: July 2016

While Marsden's solution C leaves residuals with the relatively small [vv] of 13.73, it should be realized that this representation of the observations of Eros does not satisfy the fundamental principle of the least squares method, in so far as the associated value of [vv] is not a minimum with respect to small arbitrary deviations from solution C. As a matter of fact, there is an infinite number of “solutions” with [vv] between the 13.73 of Marsden's solution C and the 8.66 of his solution A, each of these being associated with a certain arbitrarily prescribed value of the mass of Mars and with a related mass of Earth + Moon. Of this infinite series of solutions, only solution A is a least squares solution in the true sense, with a minimum value of [vv]. This can be seen and verified as follows.
Review of the system of astronomical constants
Authors: Wilkins G. A.
Published: July 2016

The purpose and principles of construction of a system of astronomical constants are described. The relationships between the constants are considered; all constants are defined precisely and a clear distinction between fundamental and derived constants is made. The system thus developed differs in some respects from the current system. The practical steps required to implement the formal adoption of such a new system are discussed.
Astronomical constants: a survey of determined values
Authors: Böhme S. , Fricke W.
Published: July 2016

The authors give the main relations between fundamental and derived constants in analytical and numerical forms. Then, they enumerate and comment results of determinations of parameters of the figure and gravity field of the Earth, solar parallax, constant of lunar equation, the masses of planets, the constants of aberration, of nutation and of precession and give an extensive list of references.
Procès-verbaux des séances
Authors: Kovalevsky J. , Message P. J.
Published: July 2016

Cette séance publique s'est tenue au grand amphithéâtre de l'Institut d'Astrophysique, le lundi 27 mai 1963 à 10 h 30 m sous la présidence de M. Clemence.
Recent developments in stellar dynamics
Authors: Contopoulos G.
Published: July 2016

In the Introduction, the main trends of present-day stellar dynamics are described, namely the application of numerical experiments and the renewed interest in then-body problem, that brings stellar dynamics close to celestial mechanics.

Then a number of new results concerning applications of the third integral are described: (a) The “tube” and “shell” orbits are explained as due to near commensurabilities in the unperturbed frequencies along the directionsxandy.(b) In non-smooth potentials, in the form of waves or hills superimposed over a smooth potential, the transition from isolating to quasi-isolating and ergodic integrals is described. (c) The non-ergodic character of the non-linear system described by Fermi-Pasta-Ulam is explained.
Encounterless stability of stellar systems
Authors: Lynden-Bell D
Published: July 2016

An energy principle which gives a sufficient condition for the stability of a stellar system is derived. There is a similar energy principle in self-gravitating gas dynamics which is necessary and sufficient. Comparison enables one to infer the stability of a stellar system from that of a gaseous system with the same density distribution.
The motion of a star in the Galaxy
Authors: Hori Gen-Ichiro
Published: July 2016

A potentialV0is found that represents Schmidt's model of the Galaxy and which admits Hamilton-Jacobi separability. Then a new integral, quadratic in the velocities and independent of the energy integral, is found. All the orbits are boxes.
A third order canonical approximation of the general solution of the restricted problem of three bodies in the neighbourhood of L4
Authors: Deprit A.
Published: July 2016

A canonical transformation of variables is introduced in the plane restricted three-body problem which gives the Hamiltonian in the form of a power series with normalized second order terms. Then a generating function is constructed, step by step, that permits the definition of new action and angle variables, such that the Hamiltonian is independent of the angle variables. This procedure has been done explicitly up to the third order terms.
Special cases of the restricted problem of three bodies
Authors: Schubart J.
Published: July 2016

The long-period effects in nearly commensurable cases of the restricted three-body problem were studied according to the ideas of Poincaré. The secular and critical terms of the disturbing function were isolated by a numerical averaging process, by use of an IBM 7094 computer.
Near-commensurate satellite orbits in the solar system
Authors: Goldreich P.
Published: July 2016

An explanation of the improbably large number of near-commensurate pairs of satellite mean motions is proposed. It is shown that special cases of near-commensurate mean motions are stable under tidal forces. At least seven of the best illustrations of commensurabilities in the solar system have this stability. The significance of these stable configurations to the evolution of satellite systems is discussed.
The influence of the re-radiation of the earth on the motion of the artificial satellites
Authors: Sehnal L.
Published: July 2016

The components of the pressure of the radiation, reflected from the Earth, are derived. The two cases, when the satellite does or does not enter the Earth's shadow are investigated. The components of the disturbing function are derived and can be used in computing the perturbations of the orbital elements by the Lagrangian equations. The results are used for the computation of the changes of the orbital period and some numerical results are given.
Lunar Occultations: From Past to Future Achievements
Authors: Richichi A.
Published: July 2016

For several decades, lunar occultations have represented a powerful and productive technique for high angular resolution investigations of a broad class of astronomical sources: from stellar angular diameters to close binaries, from circumstellar shells to the Galactic Centre.

The resolution and sensitivity offered by lunar occultations still compare favorably with the capabilities of other more modern methods in the optical and near-infrared. A remarkable fact, when one considers that during the past 20 years practically nothing or very little has changed in the way we observe lunar occultations: a sharp contrast with the impressive technological and scientific advancements of other techniques.

The novel possibility of using small areas of fast-readout, low-noise array detectors to record lunar occultations, however, is about to bring radical improvements. We discuss the impact of such detectors on the efficiency of observation and the gain for what concerns the resolution and sensitivity of lunar occultations measurements. New applications such as wavelength-resolved observations and investigations of low-contrast extended sources appear particularly interesting.
VLBA Phase-Referencing
Authors: Beasley A.J. , Conway J.E. , Diamond P.J. , Cotton W.D. , Vermeulen R.C.
Published: July 2016

Residual delay errors in VLBI data limit the image sensitivity and dynamic range attainable using current calibration techniques such as self-calibration. Applying phase corrections derived from regular observations of nearby calibrators (phase-referencing), the residual delay errors on a target source can be reduced, increasing coherent integration times. In this paper we present the results of a series of observations made with the VLBA to examine the effectiveness of phase-referencing for improving instrumental phase stability. Optimum observing strategies when studying weak (~ mJy) sources are discussed.
MERLIN — A Phase-Stable ‘VLBI’ Array
Authors: Muxlow T.W.B.
Published: July 2016

The recent upgrading of MERLIN has resulted in a much improved array with both increased sensitivity and higher angular resolution. At L-band and higher frequencies the array is now operated in a manner similar to the VLA with routine phase calibration every few minutes using a nearby compact source. An automatic data analysis “pipeline” has been developed using AIPS software. This enables MERLIN data to be routinely processed to produce images in all Stokes parameters and with positional accuracy much better than the size of the restoring beam.
The Southern Hemisphere VLBI Experiment Program, SHEVE
Authors: Jauncey D. L. , Reynolds J. E. , Tzioumis A. K. , Ferris R. H. , Norris R. P. , Sinclair M. W. , Migenes V. , Gough R. G. , Wark R. M. , Preston R. A. , Meier D. L. , Murphy D. W. , Jones D. L. , Hoard D. W. , St John Mary E. , Skjerve L. , King E. A. , McCulloch P. M. , Lovell J. E. J. , Hamilton P. A. , Costa M. E. , Blair D. G. , Edwards P. , Clay R. W. , Campbell-Wilson D. , Amy S. W. , McAdam W. B. , White G. L. , Jones P. A. , Nicolson G. D.
Published: July 2016

The Southern Hemisphere VLBI Experiment (SHEVE) program is aimed at producing high-resolution images of southern radio sources. The radio telescopes of the present SHEVE array are described below and some recent results presented.
Motion of the Delay Lines of an Optical Interferometer when Reconstructing an Image by Redundant Spacing Calibration
Authors: Nancy Ageorges , Pierre Cruzalebes , Gérard Schumacher
Published: July 2016

In an optical interferometer, the delay lines compensate the optical path difference between the different arms of the interferometer, so that the interference patterns, which contain the information, can be observed. Thanks to the phase closure technics, the phase information can be extracted, despite the random phase shifts introduced by the atmospheric turbulence. As we used the redundant spacing calibration to reconstruct an image, the telescopes of the interferometer have to be arranged according to a given iterative procedure. The advantage of this technics is to enable the reconstruction of an image without any a priori knowledge on the object. But this implies constraints on the configurations of the telescopes array, and therefore on the offsets and on the kinematics of the delay lines. Their motion have been studied to define the future layout of the 3 telescopes optical interferometer of the Calern's Observatory (CHARON III project) and also to define the operational procedure.
Optical Fibres in Radioastronomy
Authors: Young Alan C.
Published: July 2016

Within the recently completed Australia Telescope, optical fibres are used extensively to carry wideband IF data, LO reference signals, timing signals and computer communications. This paper discusses the various options considered in the design of the optical fibre system.
Recent Developments in mm and Sub-mm Interferometry
Authors: Ishiguro M.
Published: July 2016

Four existing millimeter arrays have been very productive in the last few years and are currently being expanded in their capabilities. Recent technical developments in these arrays as well as the prospects for submillimeter interferometry and larger arrays are presented.
Laser Guide Star Adaptive Optics on the 1.5 Meter Telescope at the Starfire Optical Range
Authors: Fugate R. Q.
Published: July 2016

The Starfire Optical Range 1.5 m telescope is equipped with a 241 actuator adpative optics system operating at visible wavelengths. The system can use either natural or laser guide star beacons for sensing wavefront distortions induced by atmospheric turbulence. This paper describes the main parameters of the system and presents a few examples of experimental results. The best results are Strehl ratios of 0.64 (star beacon) and 0.48 (laser beacon), both having full-width-half-maximum point spread functions of 0.13 arc second (0.88 μm).
Minimum Redundant Aperture Masking Interferometry With Tip-Tilt Wavefront Correction
Authors: Nishikawa Jun , Hayano Yutaka , Takato Naruhisa , Noguchi Motokazu , Iye Masanori , Morita Koh-Ichiro , Ishiguro Masato
Published: July 2016

We made aperture masking optical interferometry experiments using up to 30 apertures and with a tip-tilt correction of wavefront error. We examined the performance of minimum redundant configurations of 11–30 sub-apertures on the pupil plane mask. These configurations have two advantages; the redundancy noise is as small as realized in non-redundant masking method, and the uv-coverage is as high as in speckle interferometry enabling to get reconstructed images without mask exchange. We also examined the effect of tip-tilt wavefront correction within a telescope pupil in front of the aperture masking optics. The light coherency between sub-apertures was shown to increase by the correction.
MAPPIT: Optical Interferometry with Non-Redundant Masks
Authors: Bedding T. R. , Robertson J. G. , Marson R. G.
Published: July 2016

MAPPIT (Masked APerture-Plane Interference Telescope) is an optical interferometer mounted at the coudé focus of the 3.9 m Anglo-Australian Telescope. The instrument, shown schematically in Fig. 1, uses a pupil mask with five apertures of diameter ≲r0. The apertures are arranged in a linear non-redundant array, with the spacings chosen to optimize the spatial frequency coverage (R. G. Marson, these Proceedings).
High Angular Resolution Observations of Her 36
Authors: Stecklum B. , Howell R.R. , Eckart A. , Richichi A.
Published: July 2016

The star Herschel 36 (Her 36) which ionizes most of the Hourglass nebula has been observed during a lunar occultation as well as by speckle interferometry in the near infrared (NIR). From the lunar occultation data the strip brightness profile has been extracted which shows that in the L′ band Her 36 is extended with a FWHM of 0.45″. Subsequent speckle interferometry revealed 11 sources in a 6′ × 6′ area at a level of 0.15″ resolution. From the comparison of the brightness profile obtained by the occultation and the strip brightness profile synthesized from the speckle image, we conclude that Her 36 is surrounded by a very young infrared cluster.
Diffraction Limited Near Infrared Imaging of the Central Parsec of the Galaxy
Authors: Eckart A. , Genzel R. , Hofmann R. , Sams B.J. , Tacconi-Garman L.E.
Published: July 2016

We present deep 1.6 and 2.2 μm images of the central parsec of the Galaxy at a resolution of 0.15″. Most of the flux in earlier seeing limited images comes from about 340 unresolved stellar sources with K≤14. The IRS 16 and 13 complexes are resolved into about two dozen and half a dozen sources, a number of which are probably luminous hot stars. We confirm the presence of a blue near infrared object (K≈13) at the position of the compact radio source Sgr A∗. The spatial centroid of the source number distribution is consistent with the position of Sgr A∗ but not with a position in the IRS 16 complex. The stellar surface density in the central 10″ is very well fitted by an isothermal cluster model with a well defined core radius. The derived core radius of all 340 sources is 0.15±0.05 pc. The central stellar density is a few times 107 M⊙ pc−3. Buildup of massive stars by merging of lower mass stars and collisional disruption of giant atmospheres are very probable processes in the central 0.2 pc.
The Extended Hα Component of T Tau
Authors: Thiébaut E. , Devaney N. , Foy R. , De Batz B. , Blazit A. , Bonneau D. , Bouvier J. , Thom Ch.
Published: July 2016

We report the observation of T Tau by visible speckle interferometry at the CFHT. The observations were carried out at two wavelengths simultaneously. Each image was split into two, allowing improved data processing. The 4-channel photon-counting detector CP40 was used. We have discovered that 30% of the total energy at Hα is emitted by an extended elliptical component, with a FWHM of 70 marcsec. In the neighbouring continuum, T Tau is not resolved by the 3.60 m CFHT. We briefly discuss the astrophysical consequences of this new result.
HIRAS: High-Resolution IRAS Images
Authors: Bontekoe Tj. Romke , Kester Do
Published: July 2016

The InfraRed Astronomical Satellite (IRAS) all-sky survey was designed and optimized for the detection of point sources. This allowed the survey to be conducted in the form of narrow strip scans with redundant coverage of the sky, but with non-uniform covering densities. The data shows in addition to point sources many sources of extended emission, which are best analyzed from images. However, the non-uniform coverage now forms a significant obstacle in the image (re-)construction. Low resolution images, such as in the Infrared Sky Survey Atlas, yield spatial resolutions of 5–10 times the IRAS telescope diffraction limit; HIRAS improves this to 1–2 times!
VLBI Astrometry
Authors: Reynolds J. E.
Published: July 2016

VLBI is at present the most accurate technique for measuring radiosource positions and the only method capable of high precision for a reasonable number of sources. The applications of VLBI astrometry in stellar, Galactic and extra-Galactic regimes are reviewed. In particular, substantial progress has been made in the last few years towards a global reference frame of extragalactic radiosource positions. The status of this frame, and of the link to the optical reference frames is also described.
The Ultimate Radio Resolution
Authors: Kardashev N.S. , Gurvits L. I. , Tsarevsky G.S.
Published: July 2016

Scientific objectives and some technical issues of Space VLBI (SVLBI) are considered. Two SVLBI missions under preparation – RadioAstron and VSOP – are briefly described.
Constraints on Interactions and Mergers from dSph Galaxies and Globular Clusters
Authors: Grebel E.K.
Published: July 2016

Observations at high redshifts are revealing numerous interactions and ongoing mergers. Our own Milky Way is currently merging with the Sagittarius dwarf spheroidal (dSph) galaxy. Past mergers with dwarf galaxies may have contributed significantly to the Galactic halo and possibly to the thick disk. The properties of Local Group dSphs and halo globular clusters impose constraints on the merger history of the Milky Way.
N-Body Simulations of the Magellanic System Including Gas Dynamics and Star Formation
Authors: Yoshizawa A.M. , Noguchi M.
Published: July 2016

The system of the Magellanic Clouds is considered to be dynamically interacting among themselves and with our Galaxy. This interaction is thought to be the cause of many complicated features seen in the Magellanic Clouds and the Magellanic Stream (see Westerlund 1990, A&AR, 2, 27). In order to better understand the formation and evolution of the Magellanic System, we carry out realistic N-body simulations of the tidal distortion of the Small Magellanic Cloud (SMC) due to our Galaxy and the Large Magellanic Cloud (LMC).
Tidal Dwarf Galaxies
Authors: Duc P.-A. , Mirabel I.F.
Published: July 2016

We review the observational evidences for tidal dwarf galaxies, a class of small galaxies formed out of the tidal debris of collisions between massive galaxies. Tidal dwarfs are found far from the interacting parent galaxies, associated with massive clouds of atomic hydrogen located at the tip of long tidal tails. These newly formed galaxies are among the best cases for the study of galaxy formation in the nearby Universe.
Extended Gas in Interacting Systems
Authors: Combes F.
Published: July 2016

HI observations have revealed large gaseous extensions in interacting and merging systems. The interstellar gas is obviously dragged out in tidal tails during an encounter, and the percentage of HI in the tails increases with the merging stage. However, the opposite is true for the molecular gas, which is observed highly concentrated towards the nuclei of interacting galaxies, amounting to a significant fraction of the dynamical mass. Statistically, there appears to be more gas observed in interacting galaxies than in normal, isolated ones. As N-body simulations show, the gas is driven inwards in the interaction process by the strong gravity torques, before being consumed through star formation in the triggered starbursts. We review here all observations that could bring more knowledge about the state of the gas in the outer parts of galaxies, and about accretion processes. The link with the observations of the Lyα absorbers at low and high redshifts is discussed.
Collisional Ring Galaxies
Authors: Appleton P.N.
Published: July 2016

Ring galaxies are believed to represent a special case of a collision between two galaxies, in which one of the galaxies impacts and passes through the center of another disk system (e.g. Lynds & Toomre 1976). Although rare, this kind of low orbital-angular-momentum collision leads to a recognizable structure, namely a luminous blue star-forming ring (Appleton & Marston 1997), which should be easily identifiable even at moderate redshift. Indeed, Lavery et al. (1996) have used this fact, and their relative rarity at low-redshift, to conclude that rings (and therefore presumably all collisions) are over-represented in deep HST fields.
Dynamical Properties of Tidally-Induced Galactic Bars
Authors: Miwa T. , Noguchi M.
Published: July 2016

We have simulated a series of N-body models of tidal encounters between a disk galaxy and a perturbing galaxy to investigate the dynamical properties of tidally-induced galactic bars (Noguchi 1987, MNRAS, 228, 635). We have also calculated N-body models on isolated galaxies with bar-unstable disks (Ostriker & Peebles 1973, ApJ, 186, 467) to make a comparison between galactic bars of different origins (Miwa & Noguchi 1997, submitted).
Globular Cluster Systems of Elliptical Galaxies
Authors: Zepf Stephen E. , Ashman Keith M.
Published: July 2016

We review the observed properties of globular cluster systems and their implications for models of galaxy formation. Observations show that globular clusters form in gas-rich mergers, and that bimodal metallicity distributions are common in the globular cluster systems of ellipticals, with the metal-poor population more extended than the metal-rich one. These are three of the four predictions of the simple merger model of Ashman & Zepf (1992). The fourth prediction concerns the properties of the globular cluster systems of spirals, and is still to be tested by observation. Adopting Occam's razor, the confirmation of the fundamental predictions of the merger model from both young and old globular cluster systems is strong evidence that typical elliptical galaxies formed from the mergers of spiral galaxies. However, the simplifying assumptions of the Ashman-Zepf merger model limit its applicability to certain complex situations such as the formation of cD galaxies. We conclude this review by introducing new observational and theoretical programs that will further the understanding of the physical mechanisms of globular cluster and galaxy formation.
Globular Clusters in Elliptical Galaxies: Constraints on Mergers
Authors: Forbes Duncan A.
Published: July 2016

There exists a relationship between globular cluster mean metallicity and parent galaxy luminosity (e.g. Brodie & Huchra 1991; Forbes et al. 1996), which appears to be similar to that between stellar metallicity and galaxy luminosity. The globular cluster relation has a similar slope but is offset by about 0.5 dex to lower metallicity. The similarity of these relations suggests that both the globular cluster system and their parent galaxy have shared a common chemical enrichment history. If we can understand the formation and evolution of the globulars, we will also learn something about galaxy formation. With this aim in mind we have created the SAGES (Study of the Astrophysics of Globular clusters in Extragalactic Systems) project. Project members include Brodie, Elson, Forbes, Freeman, Grillmair, Huchra, Kissler–Patig and Schroder. We are using HST Imaging and Keck spectroscopy to study extragalactic globular cluster systems. Further details are given at http://www.ucolick.org/~mkissler/Sages/sages.html.
The Globular Cluster System of NGC 1399: Optical HST Imaging and ESO (Ground-Based) Near-IR Imaging
Authors: Goudfrooij Paul , Alonso M. Victoria , Minniti Dante
Published: July 2016

We report on an ongoing study of the optical–near-IR colors of globular clusters (GCs) in E galaxies. The motivation is that (i) HST images give the necessary resolution to discriminate against foreground stars and background galaxies, while the photometry goes very deep; (ii) Near-IR observations reach only the brightest clusters, but provide a much larger color baseline which is very useful to e.g., identify intermediate-age clusters such as those found in the LMC and in NGC 5128 (cf. Minniti et al. 1996, ApJ, 467, 221), and to measure more accurate metallicities, particularly at the metal-rich extreme of the metallicity distribution.
Orthogonal Gaseous Disks in the E5 Galaxy IC 4889
Authors: Beltrán J.C. Vega , Corsini E.M. , Bertola F. , Pizzella A.
Published: July 2016

IC 4889 is an apparently normal E5 elliptical (Jedrzejewsky 1987, MNRAS, 226, 747) with an extended ionized gas emission (Macchetto et al. 1996, A&AS, 120, 463). We performed long-slit spectroscopic observations along different position angles: 0°, 10°, 90° and 135°.
Starbursts Triggered by Cloud Compression in Interacting Galaxies
Authors: Jog Chanda J.
Published: July 2016

We propose a physical mechanism for the triggering of starbursts in interacting spiral galaxies by shock compression of the pre-existing disk giant molecular clouds (GMCs). We show that as a disk GMC tumbles into the central region of a galaxy following a galactic tidal encounter, it undergoes a radiative shock compression by the pre-existing high pressure of the central molecular intercloud medium. The shocked outer shell of a GMC becomes gravitationally unstable, which results in a burst of star formation in the initially stable GMC. In the case of colliding galaxies with physical overlap such as Arp 244, the cloud compression is shown to occur due to the hot, high-pressure remnant gas resulting from the collisions of atomic hydrogen gas clouds from the two galaxies. The resulting values of infrared luminosity agree with observations. The main mode of triggered star formation is via clusters of stars, thus we can naturally explain the formation of young, luminous star clusters observed in starburst galaxies.
NIR Line Observations of Starburst Galaxies
Authors: Sugai H. , Malkan M.A. , Ward M.J. , Davies R.I. , McLean I.S.
Published: July 2016

We have obtained images of the H2and Brγ emission lines in the galaxy interacting system NGC 3690 + IC 694. We have also obtained simultaneous H- and K-band spectra for three of its 2μm continuum peaks. The most detectable line emission is concentrated at the continuum peaks. Therefore, the emission lines as well as stellar absorption lines can be used as tracers of the activity in the nuclei themselves. From the strong Brγ and marginal detection of Br10 at the nucleus of IC 694, we derive a large extinction for the fully ionized gas in this nucleus. If we adopt this extinction also for the [Fe II]1.64μm emission, the extinction-corrected [Fe II]1.64μm/Brγ ratio will lie at the higher end of starburst galaxies, and is typical for AGNs or AGN/starburst composites. This might imply that many SNRs are involved in the starburst at this nucleus, unless it includes an AGN. All of our results for Component C, including very little CO absorption in the K band, a largeEW(Brγ), a small H2/Brγ ratio, the effective temperature (Teff≃ 40,000K) derived from HeI 1.70μm/Br10 and HeI 2.06μm/Brγ, are consistent with a very young starburst.
ASCA Observations of Luminous Infrared Starburst Galaxies
Authors: Watarai H. , Misaki K. , Terashima Y. , Nakagawa T.
Published: July 2016

We present recent results of X-ray observations of two luminous infrared galaxies, NGC3690+IC694 (Arp299) and NGC1614 obtained by the Japanese X-ray astronomical satellite ASCA. Both galaxies have quite high infrared luminosity (> 1011L⊙) and strong evidence of merger.
Ultraluminous Infrared Galaxies
Authors: Sanders D.B. , Surace J.A. , Ishida C.M.
Published: July 2016

At luminosities above ~ 1011L⊙, infrared galaxies become the dominant population of extragalactic objects in the local Universe (z < 0.5), being more numerous than optically selected starburst and Seyfert galaxies, and QSOs at comparable bolometric luminosity. At the highest luminosities, ultraluminous infrared galaxies (ULIGs: Lir > 1012L⊙), outnumber optically selected QSOs by a factor of ~ 1.5–2. All of the nearest ULIGs (z <0.1) appear to be advanced mergers that are powered by both a circumnuclear starburst and AGN, both of which are fueled by an enormous concentration of molecular gas (~ 1010M⊙) that has been funneled into the merger nucleus. ULIGs may represent a primary stage in the formation of massive black holes and elliptical galaxy cores. The intense circumnuclear starburst that accompanies the ULIG phase may also represent a primary stage in the formation of globular clusters, and the metal enrichment of the intergalactic medium by gas and dust expelled from the nucleus due to the combined forces of supernova explosions and powerful stellar winds.
Radio Source Surveys: Mergers at High Redshifts?
Authors: McCarthy Patrick J.
Published: July 2016

The early study of radio sources at visible wavelengths and the first empirical evidence that galaxies can have strong dynamical interactions are closely intertwined. Baade & Minkowski's (1954) model of Cygnus A as a pair of galaxies in collision, while now believed to be incorrect, presaged the merger-driven picture for the generation of radio sources (e.g. Heckman et al. 1986) by some 30 years. Morphological evidence for an association between mergers and radio loud AGN is seen in both the nearest radio galaxies (e.g. Cen A; Schweizer 1986) and in the most powerful sources at z ~ 0.1 - 0.3 (Stockton & Mackenty 1983; Hutchings et al. 1988; Heckman et al. 1986).
CFHT Adaptive Optics Imaging of Active Galaxies
Authors: Hutchings J.B.
Published: July 2016

The CFHT adaptive optics camera uses a visible light guide signal from a star to operate a bimorph mirror. The system is a unit that is operated by the observer and can be used with CCD or HgCdTe detectors. Pixel sizes are of order 0.04″. The amount of correction varies as the guide star brightness, the angular distance from it, and the natural seeing at the time. With good CFHT conditions, a guide star of 13 mag will give JHK images of FWHM near to the diffraction limit (0.1 to 0.15″) up to 20″ away. Correction is worse in the optical, but images of 0.2″ or better can be obtained in R and I-band. The camera performance is described by Rigaut et al (1998).
Dynamical Explorations of Nuclear Structures in Barred Galaxies
Authors: Anosova J. , Benedict G.F.
Published: July 2016

NGC 4314 (Benedict et al. 1996) has a complex nuclear morphology with recent star formation confined to a nuclear ring. HST observations resolve the nuclear ring into multiple sites of new star formation and resolve the associated dust lanes into discrete clouds. We construct dynamical models of this galaxy in order to provide plausible identification of the dynamical processes that led to the formation of the observed structure. We assume that the center of this galaxy contains a very massive double black-hole, surrounded by relatively low-mass particles - the star clusters as well as gas and dust complexes. Our previous work (Anosova & Anandarao 1994, Anosova & Tanikawa 1995) showed that the dynamical evolution of such a model produces many structures similar to those observed in galaxies of diverse types: spiral and elliptical galaxies, interacting galaxies, and various types of flows and jets. In the present work, we consider a number of such models with different initial parameters. We study their dynamical evolution of the gravitational N-body problem, taking into account strong interactions of bodies. Comparison of the evolution of our models with the observed structure, distributions and motions of stars, gas, and dust complexes in NGC 4314 shows good agreement. The model predicts the velocity fields observed in this galaxy.
Testing the Merger Hypothesis of Powerful Radio Galaxies
Authors: Evans Aaron S. , Sanders D.B. , Mazzarella Joseph M.
Published: July 2016

We present K′-band imaging and millimeter (CO) spectroscopy of a 60 and 100 μm flux-limited sample of 35 low redshift, powerful radio galaxies (LzPRGs: P178MHz > 1023.5 W Hz−1 and 0.01 < z < 0.22). These observations are being obtained to test the hypothesis that the radio activity in LzPRGs is triggered by the merger of gas-rich galaxies, as well as to look for evolutionary correlations between the degree of irregularity in the K′-band morphologies, the amount of star-forming molecular gas, and the radio morphologies.
Merging Galaxies with Active Nuclei
Authors: Kollatschny W.
Published: July 2016

We are investigating a sample of nearby interacting and merging galaxies showing starburst properties and/or nonthermal nuclear activity (e.g. Mrk 231, Mrk 739, Mrk 1027, NGC 2992, Arp 92).
X-Ray Study of Ultraluminous Infrared Galaxies: ASCA Results of IRAS20551-4250 and IRAS23128-5919
Authors: Misaki K. , Terashima Y. , Watarai H. , Kunieda H. , Iwasawa K. , Taniguchi Y.
Published: July 2016

We observed two ULIRGs, IRAS 20551–4250 and IRAS 23128–5919 with the X-ray satellite ASCA. Both of them are merger, 100μm bright galaxies with LIR ~ 1012L⊙ and have a “warm” IRAS color (25μm/100μm ≥ 0.2), so the presence of an AGN would be expected.
Near-Infrared Observations of a Type-2 QSO at z = 0.9
Authors: Nakanishi K. , Akiyama M. , Ohta K. , Yamada T.
Published: July 2016

We report the results of near-infrared observations of a type-2 QSO, AX J08494+4454 at z = 0.9 which was identified in our optical follow-up observations of the ASCA Lynx deep survey. This object has a hard X-ray spectrum with an X-ray luminosity of about 1×1044 erg s−1 in 2–10 keV. The optical spectrum shows high-excitation and high-ionization lines but no significant broad Hβ emission. These properties strongly suggest that this object is a “type-2” QSO (Ohta et al. 1996).
ASCA Observations of the Type-2 Quasar RXJ13434+0001 at z = 2.35
Authors: Yamada T. , Ueda Y. , Takahashi T. , Ohta K. , Cappi M. , Ohtani C. , Ishisaki Y.
Published: July 2016

RXJ 13434+0001 is a rare example of radio-quiet type-2 quasars at high redshift. It was discovered through deep ROSAT observations and identified with a galaxy with a strong but narrow Lyα emission line at z = 2.35. In order to constrain the hard-X-ray properties we observed RXJ 13434+0001 with ASCA. The main purpose is to study the origin of the X-ray emission observed with ROSAT. If it is a scattered component from a strongly absorbed AGN, we could see it much brighter in the hard X-ray band.
Radio Diagnostics of Galaxy Interactions
Authors: Menon T.K.
Published: July 2016

The Hickson Compact Groups (Hickson 1982) are relatively isolated systems of galaxies with projected separations comparable to the diameters of the galaxies themselves and are an ideal laboratory for the study of the effects of interactions on the various properties of galaxies. Roughly one third of the galaxies in HCG show clear signs of interaction such as tidal distortion, truncation, and peculiar rotation curves. Galaxies that are not now interacting may have suffered past interactions or mergers. My study is based on a VLA survey of galaxies of different morphologies in 65 Compact Groups from Hickson's (1982, 1993) catalogue and only groups with minimum of 4 accordant velocities were included in the study. This final sample consisted of 298 galaxies (80E, 92S0, 126S). The observations were carried out using the VLA in various configurations at wavelengths of 20cm and 6cm over a period of several years. The angular resolutions ranged from 20″ to 0.3″ and non-detection sensitivities ranged from 1 mJy to 0.3 mJy for different observations. A total of 86 galaxies were detected as radio sources (32ES0, 54S).
Colour Gradients in Clusters of Galaxies
Authors: Suran M.D. , Popescu N.A.
Published: July 2016

In this paper we present a new indicator of the evolution of galaxies in clusters (both galactic and intrinsic cluster evolutionary phenomena) – the colour gradient in clusters of galaxies.
The K-Band Hubble Diagram for the Brightest Cluster Galaxies: A Test of Galaxy Formation Models
Authors: Aragón-Salamanca A. , Baugh C.M. , Kauffmann G.
Published: July 2016

We analyze the K-band Hubble diagram for a sample of brightest cluster galaxies (BCGs) in the redshift range 0 < z < 1. We confirm that the scatter in the absolute magnitudes of the galaxies is small (0.3 magnitudes). The BCGs exhibit very little luminosity evolution in this redshift range: if q0 = 0.0 we detect no luminosity evolution; for q0 = 0.5 we measure a small negative evolution (i.e., BCGs were about 0.5 magnitudes fainter at z = 1 than today). If the mass in stars of these galaxies had remained constant over this period of time, substantial positive luminosity evolution would be expected: BCGs should have been brighter in the past since their stars were younger. A likely explanation for the observed zero or negative evolution is that the stellar mass of the BCGs has been assembled over time through merging and accretion, as expected in hierarchical models of galaxy formation. The colour evolution of the BCGs is consistent with that of an old stellar population (zform > 2) that is evolving passively. We can thus use evolutionary population synthesis models to estimate the rate of growth in stellar mass for these systems. We find that the stellar mass in a typical BCG has grown by a factor ≃ 2 since z ≃ 1 if q0 = 0.0 or by factor ≃ 4 if q0 = 0.5. These results are in remarkably good agreement with the predictions of semi-analytic models of galaxy formation and evolution set in the context of a hierarchical scenario for structure formation.
Molecular Gas in Hickson Compact Groups
Authors: Leon S. , Combes F. , Menon T.K.
Published: July 2016

Compact groups are ideal sites to study the influence of strong dynamical evolution due to environment on molecular cloud formation and star formation efficiency. We have observed 70 galaxies belonging to 45 Hickson compact groups (HCGs) in the 12CO(1→0) and 12CO(2→1) lines, in order to determine their molecular content. We compare the gas content relative to blue and LFIR luminosities of galaxies in compact groups with respect to other samples in the literature, including various environments and morphological types. We find that there is some hint, of enhanced MH2/LB and Mdust/LB ratios in the galaxies from compact group with respect to our control sample, especially for the most compact groups, suggesting that tidal interactions can drive the gas component inwards, by removing its angular momentum, and concentrating it in the dense central regions, where it is easily detected. The threshold at 20–30 kpc in mean galaxy separation for the enhancement of H2 suggests that it must correspond to an acceleration of the merging process and a significant inward gas flow. The molecular gas content in compact group galaxies is similar to that in pairs and starburst samples. However, the total LFIR luminosity of HCGs is quite similar to that of the control sample, and therefore the star formation efficiency appears lower than in the control galaxies. However this assumes that the FIR spatial distributions are similar in both samples which is not the case at radio frequencies. Higher spatial resolution FIR data are needed to make a valid comparison. Given their short dynamical friction time-scale, it is possible that some of these systems are in the final stage before merging, leading to ultraluminous starburst phases. We also find for all galaxy samples that the H2 content (normalized to blue luminosity) is strongly correlated with LFIR, while the total gas content (H2+HI) is not.
Nuclear Activity in the Hickson Compact Groups of Galaxies
Authors: Shimada M. , Nishiura S. , Ohyama Y. , Murayama T. , Taniguchi Y.
Published: July 2016

In order to study environmental effects on the nuclear activity in galaxies, we have been conducting a spectroscopic study of Hickson Compact Groups of galaxies (HCGs, Hickson 1982) which are the densest agglomeration of galaxies. We obtained nuclear spectra of 62 galaxies in 29 HCGs in the spectral range 6200–7000Å with the 188cm telescope at Okayama Astrophysical Observatory. These spectra were classified into the three types by using the emission line ratio [NII]λ6583/Hα; (1) AGN: [NII]λ6583/Hα >0.6, (2) HII nuclei: [NII]λ6583/Hα <0.6, and (3) Absorption: no emission line. We compared the nuclear activity of galaxies in HCGs with that of nearby galaxies (Ho 1996; Ho, Filippenko & Sargent 1997) which provides a representative sample of field galaxies. In early-type spirals (Sa-Sbc), the fraction of HII nuclei in HCGs is smaller than that in the field galaxies, while the fraction of absorption in HCGs is larger than that in field galaxies. On the other hand, in early-type galaxies (E-S0a) and late-type spirals (Sc-P), we found little difference in the nuclear activity between HCGs and field galaxies.
Dynamics and Interactions of High-Redshift Galaxies
Authors: Noguchi M.
Published: July 2016

A large number of high redshift galaxies observed with the Hubble Space Telescope (HST) show anomalous morphology and photometric properties, which may be an indication of evolutionary process in young galaxies. We show here by means of numerical simulations that the copious interstellar gas existing in the disks of rapidly collapsing protogalaxies can bring about these peculiarities. Gravitational instability in a gas-rich disk leads to the formation of massive gas clumps with a typical mass of 109M⊙. These subgalactic clumps make disk galaxy evolution a dynamically energetic and chaotic process, and give a natural explanation for peculiar morphology of high redshift galaxies. Moreover, the present model provides a new picture on the causal relationship between the emergence of quasar activities and the dynamical evolution of host galaxies. The clump-driven evolution model is also capable of explaining the correlations observed among present-day galaxies. Namely, the relative bulge dominance, existence of a thick disk, and a mass of the super-massive black hole situated at the galactic center should all be correlated positively. In contrast to their vigorous evolution in isolated state, primeval disk galaxies do not show any dramatic enhancement of activity or remarkable dynamical response in interaction with another galaxies.
Population Synthesis in a Universe of Interacting Galaxies
Authors: Bruzual Gustavo A.
Published: July 2016

The traditional view in population synthesis and evolutionary synthesis models assumes that galaxies can be considered closed systems. Thus, the evolution of the stellar population in galaxies which do not interact with the environment (including other galaxies) is described by the so called Pure Luminosity Evolution (PLE) model. As we have heard several times during this conference (and before), galaxies do interact and very few galaxies are expected to evolve passively. Early-type galaxies seem to behave closer to the PLE model than later types, but E galaxies in the bright phase predicted by this model at the galaxy formation epoch have not been observed. Most likely E galaxies do not form all their stars in short lived initial bursts (several talks in this conference). Number, size, and luminosity evolution is required to understand late-type and Irr galaxies. The PLE model is unable to reproduce the number counts, and color and redshift distributions of the galaxies in the HDF (Pozzetti et al. 1997).