bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimates of boundary layer parameters in the atmospheres of the terrestrial planets
Authors: Golitsyn G. S.
Published: July 2016

The similarity theory of atmospheric boundary layers is applied to an estimate of the form of vertical profiles of average wind velocity and potential temperature in the atmospheres of the terrestrial planets in day- and night-time conditions.

It is then considered, as in the case of the earth, that the magnitude of the turbulent heat flux qT during the day is about 0.1 of q(1 – A), where q is the solar constant for the planet and A is its albedo; at night, qT is several times smaller still. The friction velocity u* is taken equal to 2–5% (depending upon the stratification) of the mean wind velocity in the free atmosphere, which was adopted from previous calculations (Golitsyn, 1968).

The boundary layers in the atmospheres of Mars and Venus and in the hypothetical atmosphere of Mercury are examined in detail. Sharp temperature drops are characteristic of Mars within a few tens of meters from the surface, attaining a magnitude of several tens of degrees, especially during the day. Large changes of the wind velocity also take place in this thin lower layer. This effect results from the low density of the Martian atmosphere.

For Venus, owing to the very high density of the atmosphere, the stratification is close to neutral, i.e., the temperature profile is close to the adiabatic one and the wind profile is of a logarithmic shape.

Owing to high winds, the stratification on Mercury must also be close to neutral with respect to the wind (the profile being close to the logarithmic), but because of the expected low density, the temperature changes near the ground may still be very great.
The effect of atmospheric dynamics on the upper atmosphere phenomena of Mars and Venus
Authors: Shimizu Mikio
Published: July 2016

By the observations of Mariners and Veneras, oxygen atom deficiencies and very low exospheric temperatures were found in the upper atmospheres of Mars and Venus. There are two types of interpretations for these phenomena: photochemical ones (CO3 hypothesis), and dynamical ones. In this paper, the latter point of view is summarized. It was emphasized that the effect of atmospheric mixing due to general circulation and/or eddy diffusion is important for the understanding of the Cytherean and Martian atmospheric phenomena.
Chambre à étincelles optique pour la recherche de sources de rayons gamma
Authors: Vasseur J. , Paul J. , Parlier B. , Leray J. P. , Forichon M. , Agrinier B. , Boella G. , Maraschi L. , Treves A. , Buccheri R. , Scarsi L.
Published: July 2016

A gamma-ray telescope with a 850 cm2 multiplate spark chamber as a detector, has been used in an experiment of six balloon flights to investigate the Crab Nebula Pulsar 0532. The triggering signal is provided by a plastic scintillator-directional Čerenkov counter system. The spark chamber events are photographed by a stereo camera. The time of arrival of each event is recorded in UTC time with one millisecond accuracy, to search for a possible pulsed gamma emission from NP0532 above 50 MeV.
Experiment to Measure Hard Solar and Celestial X-Rays from the Fifth Orbiting Solar Observatory
Authors: Frost K. J. , Dennis B. R. , Lencho R. J.
Published: July 2016

In this paper we describe an experiment designed to measure solar and celestial X-rays in the energy range between 15 to 250 keV. The experiment was flown on the fifth Orbiting Solar Observatory which was launched on 22 January 1969. Up to the time of this writing the instrument continues to operate satisfactorily.
Optical Systems for UV Space Researches
Authors: Courtés G.
Published: July 2016

This paper gives a general review of the best ways to adapt the UV optical designs to the peculiar conditions of guidance of space vehicles.

(1)

Conditions to obtain useful photometric direct images of the sky (stars and nebulae) with several different receptors (photographs, image tube, TV camera etc., …). New solutions of imagery are considered.

(2)

Selection of the different bandwidths of wavelengths (filters; gratings).

An example of a new optical design, the BPM filter especially adapted to the poor conditions of guidance, is described. (Wave length selection is independent of the guidance.)

The last part of this article is devoted to a review of the dispersive optical designs adapted to space research.

Conclusions are in favour of the average size space vehicles on rockets for the time being and for large telescopes in the space platforms even if their guidance is several times worse than their optical quality.
Instrumentation of the NRL Solar Eclipse Rocket, 7 March 1970
Authors: Brückner G. E.
Published: July 2016

Five different Wadsworth mounting spectroheliographs have been flown into the total solar eclipse on 7 March 1970, on top of an Aerobee 170 rocket from Wallops Island, Virginia. Details of the instruments will be discussed. The new pointing system, consisting of a combination of inertial and target guidance, will be described.
Variations in rotation of the earth, results obtained with the dual-rate moon camera and photographic zenith tubes
Authors: Markowitz Wm.
Published: July 2016

Comparison of photographic zenith tube (P.Z.T.) observations with time derived from quartz-crystal clocks during 1951 to 1955 and with cesium standards of frequency during 1955 to 1958 indicates that the seasonal variation is nearly the same from year to year. Lunar-tidal inequalities of semi-monthly and monthly periods with amplitudes of about 0S.001 each were found. A preliminary value of the Love number,k, is derived. Observations made since 1952 with the dual-rate moon position camera are used to derive ΔT= ET – UT. Comparison of the P.Z.T. observations and atomic standards at the National Physical Laboratory and the Naval Research Laboratory shows details of the irregular variation from 1955 to 1958.
Report on the precision of atomic standards of frequency
Authors: Essen L.
Published: July 2016

Atomic frequency standards have been checked by laboratory investigations and by the intercomparison of different standards.

Existing ammonia Masers enable a frequency to be defined in terms of a spectral line with an accuracy of ±1 part in 108 and give a reproducibility under stated conditions of ±2 parts in 1010. The cesium atomic beam standard enables a frequency to be defined in terms of a spectral line with a precision of ±1 part in 1010. Comparison between the U.K. and U.S. by the radio transmissions of standard frequencies and time signals gave an average agreement of a few parts in 1010 but revealed some systematic discrepancies. Direct comparisons between three U.S. standards and the U.K. standard gave agreement to 2.2, 3.2, and 1.5 parts in 1010.
The mean distance to the Moon as determined by radar
Authors: Yaplee B. S. , Knowles S. H. , Shapiro A. , Craig K. J. , Brouwer D.
Published: July 2016

The results of 1959-1960 radar measurements of the distance of the Moon are given. The method of reduction of the data is described The possible effects of lunar topography and errors of other origins are discussed, as well as the effects of different constants such as the radii of the Earth and of the Moon.
The unit of time-interval
Authors: Sadler D. H.
Published: July 2016

It is suggested that the adoption of a physical definition of the unit of time-interval, to replace the ephemeris second, would have no serious effect on the theory and practice of dynamical astronomy, or on the system of astronomical constants.
On the existence of a third integral in a particular case
Authors: Perek L. , Peterson D. M.
Published: July 2016

A simple galactic model with a finite mass and dimensions, non-negative densities everywhere, an axis, and a plane of symmetry, exhibits box-type orbits for low energies. Depending on initial conditions the envelopes of the boxes are at least of degree 2, 4, and 6 respectively. High-energy orbits show a tendency to fill out the whole permissible area thus indicating the absence of an isolating third integral of motion.

A preliminary—but plausible—conclusion is suggested that the oscillations in a straight line are unstable in the present mass distribution.
Analytical development of the planetary disturbing function on a digital computer
Authors: Izsak I. G.
Published: July 2016

A computer program is described for the analytical development of the planetary disturbing function in the form of a fourfold trigonometric series with threefold power series as coefficients.
A new determination of the elements of the orbits of the satellites of Mars
Authors: Wilkins G. A.
Published: July 2016

Preliminary results of an analysis of visual observations over the period 1877–1928 are described, and a revised technique of analysis is proposed.
Single and double integration in the method of variation of parameters
Authors: Herrick S.
Published: July 2016

The customary replacement of the difference of two single integrals by a double integral in the variation-of-parameters equation for the mean longitude or mean anomaly is analyzed for its bearing on sets of parameters that do not include such a function. It is shown that the effect of the substitution is not such as to make it a requirement, and that other combinations of integrals, mutually exclusive with the customary one, are more appropriate to, and more effective with, other sets of parameters, especially those associated with “unified” and “universal” variables.
A method for the estimation of errors propagated in the numerical solution of a system of ordinary differential equations
Authors: Zadunaisky P. E.
Published: July 2016

Let bex′=f(t,x) a system of ordinary differential equations, with initial conditionsx(a) =s, which is integrated numerically by a finite difference method of orderpand constant steph.To estimate the truncation and round-off errors accumulated during the numerical process it is established a method based on the current theory of the asymptotic behaviour (whenh→0) of errors. This method should avoid the main difficulties that arise when the results of the theory must be applied to practical cases. The method has been successfully tested and applied to estimate the errors accumulated in a numerical computation of planetary perturbations on the orbit of a comet.
Effects of a constant force on a Keplerian orbit
Authors: Vinti J. P.
Published: July 2016

The paper investigates the effects of a constant force on a Keplerian orbit, with the aid of von Zeipel's method in Delaunay variables. There follows an application to the effect of the pressure of solar radiation on the orbit of an artificial satellite.
Transformation of tesseral harmonics under rotation
Authors: Jeffreys B.
Published: July 2016

An elementary and self-contained account is given of a method for the derivation of a transformation formula relating tesseral harmonics referred to two different sets of rectangular axes. The method depends on the relation of the transformation to the unimodular unitary (2 × 2) group; this can be seen explicitly from the definition used by Jeffreys (1). For applications to the theory of satellites see for example Kaula (2), Cook, G. E. (3) and Izsak (4). For the particular case when one of the axes is taken pointing to the pole of the orbit and another to perigee, the formula given is equivalent to that of Izsak.
Seeing
Authors: Masson Colin R.
Published: July 2016

Atmospheric turbulence limits the resolution of ground-based high-resolution telescopes. In the optical and radio regimes, the seeing may be described in similar ways, although the parameters are different.
Design and Construction of a Bean Combiner and Related Hardware
Authors: Mozurkewich David
Published: July 2016

The beam combiner for the Big Optical Array will eventually combine 6 beams. Initially it will use the 3 way beam combiner shown in Figure 1. This combiner is assembled on a 4′x7′ super-invar breadboard. Simultaneous white light fringes have been detected on all three baselines in the laboratory. This paper describes this beam combiner and the design decisions upon which it is based.
The Fringe Tracking Servo in SUSI
Authors: Lawson Peter R. , Booth Andrew J.
Published: July 2016

We present a description of the pathlength compensation system used in the Sydney University Stellar Interferometer, and report on the method of fringe tracking that is being implemented. The components of this system are discussed, including the PAPA camera used to detect chromatic fringes, the fringe tracking servo, the delay line and its control.
Iterative Blind Deconvolution Method with use of Lucy's Algorithm: Application to IR Speckle Data
Authors: Tsumuraya Fumiaki , Miura Noriaki , Baba Naoshi
Published: July 2016

Lucy's algorithm is applied to iterative blind deconvolution method. This new approach enables to reconstruct a greatly extended object from one speckle frame and to reinforce image domain constraints. A greatly extended object makes speckle images flow over detecting surface. Lucy's algorithm is accommodated to handle such an image and built into iterative blind deconvolution methods. Computer simulation and observational data analyses are conducted and the effectiveness of the proposed methods are exemplified.
Differential Diffraction in Michelson Stellar Interferometry
Authors: Hrynevych M.
Published: July 2016

Diffraction in Michelson Stellar Interferometery, with particular reference to SUSI, is examined. A justification of the use of Fresnel diffraction is made, both theoretically and experimentally, and a calculation of fringe visibility loss for SUSI is given.
Fringe Visibility and Phase Measurements
Authors: Shao M.
Published: July 2016

At optical wavelengths there are a wide variety of techniques to detect interference fringes. Because detectors in the visible/IR are energy detectors, the fringe amplitude and phase must be encoded in some manner. Two fundamentally different methods are temporal and spatial encoding. This paper briefly describes the various techniques that have been used in operational interferometers along with their advantages and disadvantages. Several fringe detectors for next-generation interferometers will also be described. These fringe detectors often combine multiple functions, such as spectroscopy and multi-beam combination.
Speckle v Non-Redundant Masking
Authors: Haniff C.A.
Published: July 2016

Unlike their radio counterparts, optical astronomers have paid relatively little attention to the role of the aperture function when designing their high resolution imaging experiments. This is despite the fact that it can be easily modified with the use of a suitable pupil plane mask. While the defining characteristics of the two most favoured pupil configurations have never been in doubt – negligible atmospheric noise in the case of a non-redundant configuration of small holes and high photon rates for a filled pupil – the relative merits of these two choices in terms of imaging performance in the presence of turbulence appear not to have been carefully investigated until very recently.

Most existing comparisons of fully-filled aperture (FFA) and non-redundant mask (NRM) based imaging strategies appear to have ignored a number of fundamental and practical difficulties that are often encountered in practice. In the intermediate regime, between very high and very low light levels, that characterizes most astrophysical applications hybrid imaging schemes seem most profitable. These utilize partially-redundant pupil geometries that combine the advantages of redundancy at low light levels without incurring the penalties associated with fully redundant beam recombination. Such pupil geometries are also useful in reducing the level of systematic effects that often plague speckle imaging experiments.
High Resolution & High Sensitivity Spectral-Line Imaging with Multiple Arrays
Authors: Migenes V. , Yates J.A. , Cohen R.J. , Shepherd M.C. , Bowers P.F.
Published: July 2016

At present there are several radio interferometer arrays ranging from the low-resolution (0.1–1″) high-sensitivity arrays such as the Very Large Array (VLA) to the high-resolution (0.0005–0.1″) low-sensitivity arrays such as MERLIN (though MERLIN, in the UK, is really in between this broad category), EVN, VLBA and SHEVE. Combining high sensitvity and high resolution is prohibitively expensive, because to have the u–v sampling of small arrays would require more and larger antenna elements. Hence high- resolution arrays have poor u–v coverage, decreasing the sensitivity of the instrument. This has a serious effect on spectral-line work, where sensitivity has already been sacrificed in the pursuit of spectral resolution.
Compact Array Mapping of the Nuclear Starburst in NGC 7552
Authors: Forbes Duncan A. , Norris Ray P. , Williger Gerry M. , Smith R. Chris
Published: July 2016

We discuss new observations of the starburst galaxy NGC 7552. From optical and near–infrared colour maps we find a red, dusty circumnuclear ring. High-resolution radio mapping from the ATCA reveals the same ring, and a number of bright blobs (probably SNRs). The ring is probably associated with gas and dust which have lost angular momenta due to torques in the bar potential and settled at the inner Lindblad resonance. These circumnuclear starburst rings may be relatively common (when mapped without the obscuring affects of dust) and may play a role in collimating material of a nuclear outflow.
Fluctuations of Polarized Radiation in a Random Magnetoplasma
Authors: Kukushkin Alexander
Published: July 2016

This paper analyses fourth-order moments of polarized radiation passing through magnetoactive plasma with random irregularities both in electron density and magnetic field. We consider the new propagation effect arising from chiral properties of random magnetoplasma. That is, the lenses formed by the same irregularities of magnetic field may be characterized by refractive properties of opposite sense vis-a-vis the rotation of wave polarization vector. This produces an appearance of slight circular polarization fluctuations arising from initially nonpolarised radiation. Analysis of the polarized radiation fluctuations may allow the spatial spectrum of magnetic field irregularities to be detected. The enchanced level of circularly polarized component, and the share of fluctuations owing to magnetic field irregularities, can be readily observed at low frequencies only, say in the radiation passing through the solar chromosphere or Jovian and terrestrial ionosphere (magnitosphere).
The Caltech-Jodrell Bank (CJ) VLBI Snapshot Surveys
Authors: Wilkinson P.N. , Polatidis A. , Henstock D.R. , Readhead A.C.S. , Xu W. , Pearson T.J. , Taylor G. , Vermeulen R.C.
Published: July 2016

Two large VLBI surveys are currently underway which utilise the snapshot technique pioneered on the VLA. With a 12–16 telescope array three ~ 20 min snapshots are sufficient to make excellent hybrid maps. Recent advances in data analysis techniques enable surveys of several hundred sources to be undertaken and reduced in under two years.
Optical Interferometry in the Multi-Speckle Mode
Authors: Reinheimer T. , Hofmann K.-H. , Weigelt G.
Published: July 2016

We have studied interferometric imaging in the multi-speckle mode by computer simulations. From various simulated data sets diffraction-limited images were reconstructed by the speckle masking method and the iterative building block method. The reconstructed images show the dependence of the signal-to-noise ratio on photon noise.
High Angular Resolution Observations of Protostellar Disks
Authors: Monin J.-L. , Bouvier J. , Malbet F.
Published: July 2016

The existence of circumstellar disks around young stellar objects like T Tauri stars is now well accepted. Such disks would have solar system sizes and, at the distance of the nearest star forming cloud, an angular diameter of 0.01 to 1 arcsecond at most, requiring very high angular resolution to be detected. Due to the nature of the emission process in circumstellar disks and to chromatic properties of ground based observations, disk imaging is expected to be more efficient in the near infrared. Also, multi-aperture interferometry in this wavelength range (1 – 10 μm) is expected to bring considerable insight into the disks properties and evolution in revealing their inner physical structure.

In this paper, we present synthetic images of circumstellar accretion disks. The images have been computed from a complete disk vertical structure model.
Stellar Diameters, Limb Darkening, Extended Atmospheres, and Shells: Observations with the MKIII Interferometer
Authors: Quirrenbach A.
Published: July 2016

The resolution of close binaries and direct measurements of stellar angular diameters were the first achievements of astronomical interferometry (Michelson and Pease 1921). Fringe tracking interferometers are now capable of producing visibility measurements which are sufficiently sensitive and well-calibrated to make more sophisticated measurements possible. Results from current instruments include measurements of limb darkening, of the wavelength-dependence of stellar diameters, and of non-spherical stars, and observations with narrow spectral bands. This paper summarizes recent results from the MkIII interferometer, concentrating on single stars and their envelopes. More detailed descriptions of the instrument and the data reduction procedures are given by Mozurkewich et al. (1991).
Tidal Interactions in M81 Group
Authors: Yun M.S.
Published: July 2016

At a distance of 3.3 Mpc, M81 group is one of the nearest groups of galaxies and thus an ideal place to study various galactic phenomena. Observations at all wavelengths can be made with high sensitivity and excellent spatial resolution (1″ = 15 pc). The three core members M81, M82, and NGC 3077 are known to be closely interacting from the 21cm HI emission studies (van der Hulst 1979, Yun et al. 1993, 1994), and all three galaxies show evidence for an AGN or starburst activity, possibly induced by the on-going tidal interactions. A more distant member NGC 2976 also shows evidence for tidal interaction within the group (Appleton et al., 1981). Therefore M81 group is an excellent test ground for studying tidal interaction and tidally induced activities.
Lopsided Galaxies and the Satellite Accretion Rate
Authors: Zaritsky Dennis , Rix Hans-Walter
Published: July 2016

Although current observations and theoretical models indicate that galaxy mergers and interactions are catalysts in the process of galaxy evolution, we have only a limited quantitative understanding of some basic aspects of the process. For example, the rate at which galaxies merge is poorly constrained. We can simplify the problem by considering only disk galaxies, which because of the fragility of their disks (cf. Tóth and Ostriker 1992) have presumably not suffered a major merger. Even so, these galaxies have almost certainly experienced the infall of small companion galaxies at some time. The Milky Way is currently experiencing the accretion of the Sagittarius dwarf (Ibata, Gilmore, & Irwin 1994) and will eventually accrete the Magellanic Clouds (Tremaine 1976). To understand how galaxies evolve, we need to have quantitative knowledge of the accretion rate as a function of mass for all types of galaxies. Here we consider only the accretion of companion galaxies (~ 10% by mass) onto large spiral galaxies.
“E+A” Galaxies: Environment and Evolution
Authors: Zabludoff Ann I.
Published: July 2016

One important approach to the study of galaxy evolution is to identify those galaxies whose spectral and/or morphological characteristics suggest that they are in transition. For example, “E+A” galaxies, which have strong Balmer absorption lines and no significant [OII] emission, are generally interpreted as post-starburst galaxies in which the star formation ceased within the last ~ Gyr (Fig. 1). This transition between a star forming and non-star forming state is a critical link in any galaxy evolution model in which a blue, star forming disk galaxy evolves into a SO or elliptical. Another possible evolutionary track is that the star formation in an “E+A” resumes at some later time, if enough gas remains in the galaxy after its starburst ends. Given this ambiguity, it is important to investigate (1) the environment's role in “E+A” evolution, (2) the stellar and gas morphologies of “E+A”s, (3) the likely progenitors of “E+A”s, and (4) how common the “E+A” phase is in the evolution of galaxies.
Dynamics of Mergers & Remnants
Authors: Barnes Joshua E.
Published: July 2016

This review focus on some issues which seem relevant to recent discussions: (1) how halo structure influences tail length, (2) the fate of power-law density cusps, (3) the results of unequal-mass disk galaxy mergers, and (4) the behavior of hot and cold gas in merging disk galaxies.
Mass Structure of Sa Spirals: NGC 2179 & NGC 2775
Authors: Corsini E.M. , Sarzi M. , Cinzano P. , Bertola F. , Pizzella A. , Persic M. , Salucci P.
Published: July 2016

Recent analysis of extended rotation curves of late-type spirals have confirmed that these objects have detectable amounts of dark matter (DM) already in the optical region, with dark-to-luminous mass ratio scaling inversely with luminosity. Since currently available rotation curves of early-type spirals are often fragmentary and not extended enough, the question remains open as to whether dark halos are unequivocally present in Sa galaxies. To address this point we have observed a sample of 7 SA's measuring major axis velocities and velocity dispersion for both stars and ionized gas. Here we present results for two objects, NGC 2179 and NGC 2775. We have constructed detailed dynamical models which, for each galaxy, explain the observed kinematics for both stellar and gaseous component and which are consistent with observed photometry. The best fit model for NGC 2179 involves an oblate isotropic rotator bulge, a thin exponential disk with the same mass-to-light ratio, and a pseudo-isothermal DM halo. The mass-to-light ratio in the inner galaxy was found to be M/LR = 4.5 (M/LR)⊙ reaching M/LR = 7.5 (M/LR)⊙ at the optical radius (Ropt). For NGC 2775 the best fit model involves an oblate isotropic rotator bulge and a thin exponential disk, with M/Lr = 3.5 (M/Lr)⊙, and M/Lr = 4.7 (M/Lr)⊙ respectively. No DM halo was needed to explain the data extending to 0.7 Ropt. In the inner regions the gas rotates as fast as stars but with negligible velocity dispersion. This rules out the case where the gas kinematics is dominated by random motion, and leads us to speculate we are seeing gas rotating on a non-equatorial plane, resulting from a past external acquisition, possibly from the companion galaxy NGC 2777.
Gasdynamics and Starbursts in Interacting Galaxies
Authors: Mihos J. Christopher
Published: July 2016

The onset of gaseous inflows and central activity in interacting galaxies is driven largely by induced bars in the host galaxies. The stability of galaxies against growing bar modes is a direct function of their structural properties — galaxies with central bulges or low disk surface densities are more stable against central starbursts than are bulgeless or disk-dominated systems. Low surface brightness galaxies prove less prone to bar formation and central starbursts than do normal high surface brightness galaxies. This stability of LSB disks also resolves many of the dynamical pitfalls encountered when attempting to link poststarburst “E+A” galaxies to interactions involving normal high surface brightness galaxy progenitors.
Luminous IR Galaxies in a Merger Sequence: Bima Co Imaging
Authors: Gao Y. , Gruendl R.A. , Hwang C.-Y. , Lo K.Y.
Published: July 2016

The power output in luminous infrared galaxies (LIGs, LIR ≳ 1011L⊙, H0 = 75 kms−1 Mpc−1) can approach the bolometric luminosity of quasars and can be provided by either starbursts or dust-enshouded QSOs, or both. Most LIGs appear to comprise of mergers of gas-rich galaxies. So, intense bursts of star formation apparently result from interaction and merging of galaxies, but the exact physical processes involved in collecting the large amount of gas involved and in initiating the starbursts are not well understood.
Gas Content of Markarian Starburst Galaxies
Authors: Kandalyan Rafik
Published: July 2016

The main results of this study can be summarized as follows: (a) The HI and CO linewidths are well correlated. Interaction between galaxies has little influence on the HI and CO line broadening. A rapidly rotating nuclear disk in the galaxy could lead to CO line broadening, while the HI line is less affected by the rotating disk. Molecular gas in Markarian galaxies is centrally concentrated. (b) For past and present star formation activity both HI and H2 components of the gas are important. The atomic and molecular gas surface densities are well correlated with blue, FIR, and radio continuum surface brightnesses, but the H2 surface density is better correlated than that of the HI. The two gas phases are also connected. (c) In general, galaxies with UV-excess (Markarian galaxies) are not distinguished by star formation properties from non-UV galaxies, however some second order differences may exist, like the relation between atomic surface density and radio continuum surface brightness.
Ocular Galaxies: NGC 2535 and its Starburst Companion NGC 2536
Authors: Brinks E. , Kaufman M. , Elmegreen D.M. , Thomasson M. , Elmegreen B.G. , Struck C. , Klarić M.
Published: July 2016

We obtained HI, radio continuum, and 12CO J = 1 → 0 observations at resolutions of 12″ to 33″ (= 2.9 - 8 kpc), and B, I, J, and K–band images, of the galaxy NGC 2535 and its small starburst companion NGC 2536. NGC 2535 has an ocular (eye-shaped) structure indicative of a recent, close, nonmerging encounter. Our observations reveal widespread high velocity dispersions (30 km s−1) in the HI gas and five clouds with masses of ~ 108M⊙ in the tidal arms of NGC 2535. CO emission was detected at the center and on the tidal tail, but close to the center, of NGC 2535; no CO emission was detected from the companion. NGC 2535 has an intrinsically oval shape to the disk, an extended (R = 48 kpc) HI envelope and an outer elliptically–shaped HI arc that may be a gravitational wake produced by the passage of the companion within or close to the extended HI envelope. The starburst companion, NGC 2536, lies in a 2 × 109M⊙ clump of HI gas at the outer end of the tidal bridge from NGC 2535. A full account our results appears in Kaufman et al. (1997, AJ, 114, 2323).
Unified Scheme for Seyferts or the Influence of Interactions?
Authors: Dultzin-Hacyan D. , Guridi Ivette Fuentes , Krongold Yair , Marziani Paolo
Published: July 2016

The first statistical study of the environment of Seyfert galaxies (of both types 1 and 2) was done by Petrosian (1982), who found that Sy2 galaxies had an excess of nearby companion galaxies with respect to field galaxies. Dahari (1985) made a similar study, and obtained that both types of Seyfert galaxies are found five times more often in interacting systems that “normal” galaxies. Fuentes-Williams & Stocke (1988) obtained the opposite result: that Seyfert galaxies have no significative excess of nearby companions, and MacKenty (1989) obtained the same result as Petrosian. The last papers appeared in 1995: Rafanelli, Violato & B.aruffolo (1995) obtained a similar result as Dahari. Laurikainen & Salo (1995) made a careful attempt to understand the discrepancies; they concluded that the incompatibilities in the results were mainly due to control sample selection, and problems in background galaxy determination. Their work confirmed the result of the first study. However, in order to explain the discrepancies between previous results, they also used incorrectly defined control samples. Objections can be made against all of these works for this only reason. We have repeated the study using, for the first time, the digitized Palomar Sky Survey plates (paSS), an automated selection procedure, and correctly defined control samples (Osterbrock 1993).
Distribution of Stochastic Forces in Gravitationally Clustered System of Galaxies
Authors: Ardi Eliani , Inagaki Shogo
Published: July 2016

We are interested in examining the influence of nearest neighbor galactic encounters in gravitationally clustered systems by using cosmological N-body simulation.
Environmental Influence on Star Formation of Galaxies in the LAS Campanas Redshift Survey
Authors: Hashimoto Y. , Oemler A.
Published: July 2016

We have used a sample of 15749 galaxies taken from the Las Campanas Redshift Survey to investigate the effects of environment on the rate of star formation (SFR) in galaxies. For each galaxy we measure SFR by [OII] emission, while a concentration index (C) is used to decouple the effect of the “morphology-environment” relation from the SFR. Galactic environment is characterized both by the 3-space local density (ρ) of galaxies and by membership in groups and clusters.
A Multi-Merging Galaxy MRK 273 with Hot Extended Gaseous Halo and an Extended Soft X-Ray Companion
Authors: Xia X.Y. , Deng Z.G. , Wu H. , Boller T.
Published: July 2016

The ultraluminous IRAS galaxy Mrk 273 is a Seyfert 2, multi-merger system with a triple-nucleus and a 20 kpc (H0 = 100 km s−1 Mpc−1) jet to the South. Also, a plume and faint tail extends ~50 kpc Northwest and there are more than 10 dwarf galaxies within 100 kpc of Mrk 273 as determined from the POSS II R and J film copy. Therefore, the precursor of Mrk 273 is probably connected with a group of galaxies.
Emission Line Galaxies at 1 < z < 1.5
Authors: Glazebrook K. , Abraham R.G. , Blake C.A.
Published: July 2016

In this paper we wish to introduce the first results on two new projects aimed at detecting emission lines in galaxies at z > 1. There are two primary motivations for doing this: Firstly to try and measure the cosmic star-formation rate at these redshifts. The combination of z < 1 redshift surveys and the discovery of the z ~ 3 Hubble Deep Field ultraviolet dropout objects has led to a ‘first draft’ history of the cosmic SFR (Fig. 1). These results are based on UV continuum fluxes, it is highly desirably to confirm these studies with line diagnostics and extend the work to the redshift of the inferred peak (z ~ 1.5).
Type IA Supernovae and Chemical Evolution of Galaxies
Authors: Nomoto K. , Kobayashi C. , Umeda H.
Published: July 2016

The cosmic/galactic chemical evolutions have been modeled with the early metal enrichment by Type II supernovae (SNe II) and the delayed enrichment of Fe by Type Ia supernovae (SNe Ia). However, the exact nature of SN Ia progenitors have been obscure. Here we present the currently most plausible scenario of the progenitor binary systems of SNe Ia. This scenario involves strong winds from accreting white dwarfs, which introduces important metallicity effects, namely, low-metallicity inhibition of SNe Ia. Resultant predictions for the Galactic/cosmic chemical evolution and the cosmic SNe Ia rate are presented. Another importance of identifying the SN Ia progenitors lies in the use of SNe Ia as a “standard candle” to determine cosmological parameters. To examine whether the “evolution” of SNe Ia with redshift and metallicity is significant, we discuss how the metallicity affects the properties of the C+O white dwarfs such as the C/O ratio, and find the metallicity dependence is rather weak.
The Chemical Evolution of Light Elements in Our Galaxy
Authors: Prantzos N.
Published: July 2016

Progress in the theory of galactic chemical evolution has been very slow and it is only in the solar neighborhood that observations constrain seriously the parameters of the various models. The history revealed on the basis of these data allows only for a small depletion of deuterium (D), less than a factor of 3 from its pregalactic value (Sec. 2.1). The observational data for the rest of the Milky Way disk are much less constraining for the models. They suggest, however, that a much larger astration (and, hence, D depletion) has taken place in the inner Galaxy; the resulting D gradient, measurable by the future FUSE-LYMAN mission, should provide invaluable information as to the past history of the disk (Sec. 2.2). Also, assuming that our Galaxy is a typical spiral, one can calculate the properties of disk galaxies as a function of redshift (in the framework of a given cosmological model) and compare to the observed properties of the extragalactic universe: global star formation rate, gas content and metal abundances in gas clouds. It turns out that D can be considerably depleted in galaxy disks, but only at low redshifts (Sec. 2.3).
A Metal Enriched Dark Cluster of Galaxies at Z = 1
Authors: Hattori M.
Published: July 2016

Looking for and studying very distant galaxy clusters, clusters at z > 1, are one of the prime subjects of the modern observational cosmology. If the metallicity of the hot intra-cluster medium in very distant galaxy clusters is measured for example, it provides fruitful informations for us to understand the formation and evolution of galaxies. However, difficulty of the study is that there is few confirmed very distant galaxy clusters yet. We first have to search for very distant clusters but it requires very deep observations. A random selection of sky is not practical. We have to select the sky. In this article, it is demonstrated that missing lens problem has close connection with very distant cluster of galaxies and dark lens searches could open a new window for studying very distant cluster of galaxies.
Constraints on Galaxy Formation from Extragalactic Globular Clusters
Authors: Brodie Jean P.
Published: July 2016

The merger model for elliptical galaxy formation has received increasing attention since it was first suggested by Toomre & Toomre (1972). Van den Bergh (1984) pointed out a problem with the idea that elliptical galaxies were formed by simply combining two, or more, spiral galaxies. He noted that the specific frequency (SN, number of globular clusters per unit galaxy light) is systematically lower for spirals than for ellipticals. Schweizer (1987) suggested that globular clusters might be expected to form in the merger process, thereby alleviating or possibly eliminating the SN problem. Ashman & Zepf (1992) developed this idea into a merger model for globular cluster formation with testable predictions.
X-Rays from Supernova 1993J and Ejecta Instabilities
Authors: Nomoto K. , Suzuki T.
Published: July 2016

Among the mechanisms of X-ray emissions from supernovae, we focus on the circumstellar interaction. In particular, we relate the new X-ray features of SN1993J to the hydrodynamical instabilities in the ejecta. First, we model the early-time two component spectral feature by invoking instabilities in the dense cooling shell in the ejecta. Second, we model the gradual increase in the X-ray light curve as X-rays emitted from the reverse shocked ejecta; here the model requires a large scale change in the density distribution due to Rayleigh-Taylor instabilities around the core-envelope interface.
Hot Gas in Groups and Their Galaxies
Authors: J. Ponman Trevor , Finoguenov Alexis
Published: July 2016

It is clear that there is an important interplay between galaxies and the group environment. At the velocity dispersions (~ 100 km s−1) characteristic of groups, the galaxies interact strongly, leading to triggering of star formation, and galaxy merging. We can expect to see evidence of such processes through differences in the properties of galaxies in groups compared to field galaxies. Conversely, the galaxies affect their environment, as is apparent from the presence of heavy elements in the hot intergalactic medium (IGM) in groups, which emit characteristic X-ray lines.
Early Results from the Low-Energy Concentrator Spectrometer on-board BeppoSAX
Authors: Parmar A.N. , Bavdaz M. , Favata F. , Oosterbroek T. , Orr A. , Owens A. , Lammers U. , Martin D.
Published: July 2016

SAX, an acronym for “Satellite Italiano per Astronomia a raggi X”, now renamed “BeppoSAX” in honor of Giuseppe Occhialini, is the first X-ray mission sensitive in the very broad energy range between 0.1 and 300 keV (Boella et al. 1997a). The Narrow Field Instruments (NFI) have approximately 1° fields of view and consist of the imaging low- and medium-energy concentrator spectrometers (LECS, 0.1-10 keV, Parmar et al. 1997; and MECS, 1-10 keV, Boella et al. 1997b), and the non-imaging high pressure gas scintillation proportional counter (HPGSPC, 3-120 keV, Manzo et al. 1997) and Phoswich detector system (PDS, 15-300 keV, Frontera et al. 1997). All the NFI are coaligned and are normally operated simultaneously. In addition, the payload includes two wide field cameras (WFC, 2-30 keV; Jager et al. 1997) which observe in directions perpendicular to the NFI. These allow the detection of X-ray transient phenomena, as well as long-term variability studies.
Photoionized Plasmas in X-Ray Binary Pulsars: ASCA Observations
Authors: Nagase Fumiaki
Published: July 2016

Massive X-ray binary pulsars have often evolved early-type companion stars which emanate strong stellar winds. X-rays emitted from the accreting neutron star irradiate and ionize the surrounding stellar wind, thus forming a photoionized sphere surrounding the neutron star. The photoionization structure of matter surrounding the neutron star was calculated by Hatchett and McCray (1977) and McCray et al. (1984), for Cen X-3 and Vela X-1 respectively.
X-Ray and Gamma-Ray Observations of Isolated Neutron Stars
Authors: Thompson D.J.
Published: July 2016

Pulsars provide useful diagnostics of isolated neutron stars, because the timing information allows many physical parameters to be derived. This brief review describes some of the X-ray and gamma-ray properties of pulsars.
Discovery of X-Ray Counterparts to Gamma Ray Bursts by BeppoSAX
Authors: Piro L.
Published: July 2016

The nature of Gamma-Ray Burst (GRB) has been the object of many investigations but their origin has remained a mistery primarily for the difficulties in finding a counterpart. This difficulty derived from the intrinsically poor positioning capability of available GRB detectors.
Quick Observations of the Fading X-Rays from Gamma-Ray Bursts with ASCA
Authors: Murakami T. , Ueda Y. , Fujimoto R. , Ishida M. , Shibata R. , Uno S. , Nagase F. ,   Isas Team, Yoshida A. , Kawai N. , Tokani F. , Otani C. ,   Riken Team, Marshall F.E. , Corbet R.H.D. , Swank J.H. , Takeshima T. , Smith D.A. , Levine A. , Remillard R.A. , Vanderspek R. ,   Rxte Team, Robinson C.R. , Kouveliotou C. , Meegan C. , Connaughton V. , Kippen R.M. ,   Batse Team, Hurley K. ,   UCB, Barthelmy S.D. ,   GCN, Piro L. , Costa E. , Heise J. , Fiore F. ,   SAX Team, Paradijs J.V. , Tanaka Y. ,   UOA, Greiner J. ,   AIP
Published: July 2016

Since the discovery of fading X-rays from Gamma-Ray Bursts (GRBs) with BeppoSAX (Piro et al. 1997, Costa et al. 1997), world-wide follow-up observations in optical band have achieved the fruitful results. The case of GRB 970228, there was an optical transient, coincides with the BeppoSAX position and faded (Paradijs et al. 1997, Sahu et al. 1997). These optical observations also confirmed the extended component, which was associated with the optical transient. The new transient are fading with a power-law function in time and the later observation of HST confirmed the extended emission is stable (Fruchter et al. 1997). This extended object seems to be a distant galaxy and strongly suggests to be the host.
X-Ray Emission from Distant Stellar Clusters
Authors: Schulz N.S. , Kastner J.H.
Published: July 2016

Observations with the Einstein Observatory indicated that stellar X-ray activity diminishes in clusters older than 70 Myr (Pleiades). ROSAT observations of older clusters also support this result (see Caillault 1995 and references therein). The timescales over which young stars diminish in X-ray luminosity depends on spectral type (Randich et al. 1996), leading to the conclusion that X-ray activity in late type PMS depends on age and stellar mass. F and G-stars approach the main sequence much faster and the diminishing rates of X-ray activity from F to M stars start to differ considerably. Kastner et al. (1997) observed that the mean of the ratio Lx/Lbol for K and M dwarf stars increases monotonically for low-mass stars from the very early T Tauri stage through the age of the Pleiades cluster, reflecting the contraction and spin-up of such stars during pre-main sequence evolution. This ratio then decreases towards middle aged stars, as late-type main sequence stars spin down. Here we extend this result by including more distant clusters that are younger overall than those considered by Kastner et al. and also including earlier spectral types.
ASCA Observations of 44I Bootis and VW Cephei
Authors: Choi Chul-Sung , Dotani Tadayasu
Published: July 2016

We analyze X-ray archive data of the W UMa-type binaries 44i Boo and VW Cep, taken with ASCA on 1994 May 10 and 1993 November 5, respectively. By analyzing the light curve of VW Cep, we find a long-duration flare of ≈ 7.5 hrs with the peak luminosity of 1.2 × 1030 ergs s−1 (0.4-3.0 keV) for the assumed distance of 23.2 pc. We also find appreciable flux variations from the light curve of 44i Boo, and the variations are erratic and are not orbital phase dependent. From the spectral analysis of both data, we see that the spectra could be reproduced by the variable abundance plasma model with a combination of two different temperatures, kT = 0.64 – 0.65 keV and kT = 1.85 – 1.91 keV.
Black Hole Disk Accretion in Supernovae
Authors: Nomura H. , Mineshige S. , Hirose M. , Nomoto K. , Suzuki T.
Published: July 2016

Massive stars in a certain mass range (20 – 40M⊙) may form low mass black holes after supernova explosions. In such massive stars, fall back of ~ 0.1M⊙ materials onto a black hole is expected due to a deep gravitational potential or a reverse shock propagating back from the outer composition interface. We study hydrodynamical disk accretion onto a new-born low mass black hole in a supernova using the SPH (Smoothed Particle Hydrodynamics) method.
The Effect of Dust Sputtering in Supernova Remnant
Authors: Kurino Takashi , Fujimoto Masayuki , Habe Asao
Published: July 2016

IRAS observations of supernova remnants (SNRs) reported that infrared luminosity from SNRs are very different, though some of them have same temperature. This is because infrared emittion depends on density of the dust grains.
X-Ray Study of Crab-Like and Composite SNRs
Authors: Torii K. , Tsunemi H. , Slane P.
Published: July 2016

We have presented X-ray observations of Crab-like supernova remnants (SNRs) (plerions) and (non-thermal) composite SNRs. We have observed several objects including 3C58, CTA1, and G292.0+1.8. Since space is limited, here we summarize results on G292.0+1.8. For the other objects, please refer to each publication (Slane et al. 1997; Torii et al. 1997).
Can Galactic γ-Ray Background be due to Superposition of γ-Rays from Millisecond Pulsars?
Authors: Bhatia V.B. , Mishra S. , Panchapakesan N.
Published: July 2016

The SAS 2 and COS B observations have established the existence of diffuse γ-rays in our Galaxy in various energy ranges. The diffuse radiation is attributed to the interaction of cosmic ray nuclei and electrons with the particles of interstellar atomic and molecular gas (via the decay of pions and bremsstrahlung, respectively). Inverse Compton scattering of interstellar photons by the high energy electrons of cosmic rays may also be contributing to this background. In addition some contribution may come from discrete sources of γ-rays.
Transition Probabilities for 1H in Strong Magnetic Fields
Authors: Benkő J. M. , Balla K.
Published: July 2016

When computing synthetic spectra we have to be aware of the strength of the lines. The determination of the required dipole strengths, oscillator strengths and transition probabilities is based on the evaluation of the dipole matrix elements. These quadratic functionals are defined by integrals over the whole space composed of the eigenfunctions P of the atomic system belonging to the eigenvalues Em and En, respectively:
Diagnostic of Astrophysical Plasma in Neighborhood of Neutron Stars
Authors: Mijatović M. , Solov'ev E.A.
Published: July 2016

If in the neighborhood of neutron stars exist clouds of hydrogen atoms, they are the natural astronomical object for realization of the model of hydrogen atom in a strong magnetic field ~ 108 T.