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astro-ph/9511033
Star-Formation Knots in IRAS Galaxies
Images of IRAS galaxies with a range of IR properties are examined for bright knots, both within and outside the galaxy. These are found almost exclusively in galaxies with steep IR spectra, but over a wide range of IR luminosity, and usually without strong nuclear activity. In most cases, the knots are likely to be st...
1995-11-08
2009-10-28
[ "astro-ph" ]
J.B. Hutchings
astro-ph/9511032
Constraints on massive black holes as dark matter candidates using Galactic globular clusters
This work considers the idea of massive black holes being the constituents of the Galactic dark matter halo. It constrains the maximum black hole mass to $\mbh \sil 5 \times 10^4 \msun$ by examining their influence on the population of globular clusters in our Milky Way. In the adopted halo model, globular clusters are...
1995-11-08
2015-06-24
[ "astro-ph" ]
Ralf Klessen and Andreas Burkert
astro-ph/9511030
Low Mass Companions to T~Tauri Stars: a Mechanism for Rapid-rise FU~Orionis Outbursts
We show that outside-in disc instabilities, which can produce rapid-\null rise FU Orionis outbursts in T~Tauri systems, are a natural consequence of the existence of protoplanetary protostellar companions. The \pcomp{} would be formed through gravitational instability on a dynamical timescale ($\sim 10^5\y$), and provi...
1995-11-08
2016-06-08
[ "astro-ph" ]
Cathie Clarke (IoA), Dave Syer (MPA)
astro-ph/9511027
Numerical study of energy diffusion in King models
The energy diffusion coefficients D_n(E) (n=1,2) for a system of equal mass particles moving self-consistently in an N-body realisation of a King model are computed from the probability per unit time, P(E, Delta E), that a star with initial energy E will undergo an energy change Delta E. In turn, P is computed from the...
1995-11-07
2015-06-24
[ "astro-ph" ]
Tom Theuns (Oxford University)
astro-ph/9511025
Tracing the Dynamics of Disk Galaxies with Optical and IR Surface Photometry: Color Gradients in M99
We present optical and IR surface photometry of M99 (NGC 4254) at g, r_S i, J and K'. We also present a K' image of M51 (NGC 5194) for comparison. Fourier decomposition of the disk light reveals that the radial distribution of power depends on wavelength, which in turn implies that the spiral structure traced in the vi...
1995-11-07
2009-10-28
[ "astro-ph" ]
Rosa A. Gonzalez and James R. Graham (UC Berkeley)
astro-ph/9511026
Metal-rich globular clusters of the Galaxy: morphology of the helium-burning "clump," and the determination of relative ages through the "$\Delta V$" method
Morphological aspects of the $V, \bv$ diagram of metal-rich globular clusters are analyzed, on the basis of stellar evolution models for horizontal-branch (HB) and red giant branch stars. These have been incorporated into detailed synthetic HB models, the influence of differential reddening upon which is also discussed...
1995-11-07
2016-08-30
[ "astro-ph" ]
M. Catelan and J.A. de Freitas Pacheco
astro-ph/9511024
Global HI profiles of spiral galaxies
In this paper we present short HI synthesis observations of 57 galaxies without HI information in the RC3. These are a by-product of a large survey with the WSRT of the neutral hydrogen gas in spiral and irregular galaxies. Global profiles and related quantities are given for the 42 detected galaxies and upper limits f...
1995-11-06
2007-05-23
[ "astro-ph" ]
J.J. Kamphuis, D. Sijbring and T.S. van Albada (Kapteyn Astronomical Institute)
astro-ph/9511023
Microlensing of pulsar radiation in the Galactic Center
We investigate the possibility of identifying massive objects (lenses) in the Galactic Center region (GC) by means of pulsar timing. The well known intensity change due to microlensing is found to be less important. For typical stellar masses, the flux magnification can be significant only if the lens passes very close...
1995-11-05
2016-08-30
[ "astro-ph" ]
N. Wex, J. Gil, M. Sendyk
astro-ph/9511022
Does There Really Exist the Problem of the Dark Matter in Spiral Galaxies?
A simple model for the dust media describing evolution of the system like spiral galaxy is considered. In contrast to previous considerations we show that the initial density fold should be quasi-one-dimensional (bar-like) instead of disc-like. The disc component of the galaxies appears only during the evolution. The m...
1995-11-04
2007-05-23
[ "astro-ph" ]
A.E.Filippov and A.S.Zhedanov (DPTI, Donetsk, Ukraine)
astro-ph/9511019
Chemical Abundances in Virgo Spiral Galaxies II: Effects of Cluster Environment
We present new measurements of chemical abundances in H II regions in spiral galaxies of the Virgo cluster and a comparison of Virgo galaxies and field spirals. With these new data there now exist nine Virgo spirals with abundance measurements for at least four H II regions. Our sample of Virgo galaxies ranges from H I...
1995-11-03
2009-10-28
[ "astro-ph" ]
Evan D. Skillman (U.Minn.), Robert C. Kennicutt Jr. (Steward Obs., U. Arizona), Gregory A. Shields (U. Texas), and Dennis Zaritsky (UCO/Lick Obs., UCSC)
astro-ph/9511017
The Origin of Extreme Horizontal Branch Stars
Strong mass loss on the red giant branch (RGB) can result in the formation of extreme horizontal branch (EHB) stars. The EHB stars spend most of their He core and shell burning phase at high temperatures and produce copious ultraviolet flux. They have very small hydrogen envelopes and occupy a small range in mass. We h...
1995-11-03
2016-02-17
[ "astro-ph" ]
Noella Lambert d'Cruz (U. Va), Ben Dorman (U. Va/NASA-GSFC), Robert T. Rood, and Robert W. O'Connell
astro-ph/9511018
Merger trees and the multiplicity function of halos
We present a new method for calculating the merger history of matter halos in hierarchical clustering cosmologies. The linear density field is smoothed on a range of scales, these are then ordered in decreasing density and a merger tree constructed. The method is similar in many respects to the block model of Cole \& K...
1995-11-03
2015-06-24
[ "astro-ph" ]
Domingos D. C. Rodrigues and Peter A. Thomas
astro-ph/9511021
Triaxial Galaxies with Cusps
We have constructed fully self-consistent models of triaxial galaxies with central density cusps. The triaxial generalizations of Dehnen's spherical models are presented, which have densities that vary as 1/r^gamma near the center and 1/r^4 at large radii. We computed libraries of about 7000 orbits in each of two triax...
1995-11-03
2009-10-28
[ "astro-ph" ]
David Merritt and Tema Fridman (Rutgers)
astro-ph/9511020
Neutral hydrogen in the nearby galaxies Dwingeloo 1 and Dwingeloo 2
We present observations made with the Westerbork Synthesis Radio Telescope of HI emission from Dwingeloo 1, a nearby barred spiral discovered during the Dwingeloo Obscured Galaxies Survey for galaxies hidden in the Zone of Avoidance, and of Dwingeloo 2, a small galaxy discovered in the beam of these WSRT observations. ...
1995-11-03
2007-05-23
[ "astro-ph" ]
W.B. Burton (Leiden Observatory) M.A.W. Verheijen (Kapteyn Astronomical Institute) R.C. Kraan-Korteweg (Observatoire de Paris) P.A. Henning (University of New Mexico)
astro-ph/9511014
Keck Spectroscopy and HST Imaging of Field Galaxies at Moderate Redshift
We present 18 spectra, obtained with the Keck 10m telescope, of faint field galaxies (19 $<$ I $<$ 22, 0.2 $<$ z $<$ 0.84) previously imaged by {\it HST's} WFPC2. Though small, our sample appears to be representative of field spirals with a magnitude--limit of I $\le$ 22. Combining the results from the spectral and ima...
1995-11-02
2009-10-28
[ "astro-ph" ]
Duncan A. Forbes, Andrew C. Phillips, David C. Koo and Garth D. Illingworth (Lick Observatory)
astro-ph/9511012
The Confluent System Formalism: II. The Growth History of Objects
With the present paper we conclude the presentation of a semianalytical model of hierarchical clustering of bound virialized objects formed by gravitational instability from a random Gaussian field of density fluctuations. In paper I, we introduced the basic tool, the so-called ``confluent system'' formalism, able to f...
1995-11-02
2009-10-28
[ "astro-ph" ]
Alberto Manrique and Eduard Salvador-Sole (University of Barcelona)
astro-ph/9511016
The Structure of CDM Halos
High resolution N-body simulations show that the density profiles of dark matter halos formed in the standard CDM cosmogony can be fit accurately by scaling a simple ``universal'' profile. Regardless of their mass, halos are nearly isothermal over a large range in radius, but significantly shallower than $r^{-2}$ near ...
1995-11-02
2007-05-23
[ "astro-ph" ]
Julio F. Navarro (Steward Observatory, University of Arizona)
astro-ph/9511009
The large scale structure of the soft X-ray background. I: Clusters of galaxies
Large-scale fluctuations of the X-ray background are investigated using the ROSAT All-Sky Survey. The autocorrelation function of the extragalactic background at 1 keV is determined at separations 0.1 - 40 deg. We detect a significant signal for separations < 6 deg, which is larger than previous upper limits. We analys...
1995-11-02
2007-05-23
[ "astro-ph" ]
Andrzej M. Soltan, Guenther Hasinger, Roland Egger, Steve Snowden and Joachim Truemper (MPE-Garching, Copernicus Center-Warsaw, NASA/GSFC-Greenbelt)
astro-ph/9511013
The Lyman Alpha Forest from Gravitational Collapse in the CDM+Lambda Model
We model the $\lya$ forest in a spatially flat, CDM model with $\Omega=0.4$, with an Eulerian hydrodynamic simulation, and find that the intergalactic, photoionized gas collapses into sheet-like and filamentary structures which produce absorption lines like those observed in the $\lya$ forest. A typical filament is $\s...
1995-11-02
2009-10-28
[ "astro-ph" ]
Jordi Miralda-Escude, Renyue Cen, Jeremiah P. Ostriker, Michael Rauch
astro-ph/9511010
The number, luminosity, and mass density of spiral galaxies as a function of surface brightness
I give analytic expressions for the relative number, luminosity, and mass density of disc galaxies as a function of surface brightness. These surface brightness distributions are asymmetric, with long tails to lower surface brightnesses. This asymmetry induces systematic errors in most determinations of the galaxy lumi...
1995-11-02
2015-06-24
[ "astro-ph" ]
Stacy McGaugh
astro-ph/9511011
The Palomar Distant Cluster Survey: I. The Cluster Catalog
We present an optical/near IR selected catalog of 79 clusters distributed over an area of 5.1~square~degrees. The catalog was constructed from images obtained with the 4-Shooter CCD mosaic camera on the Hale 5m telescope operating in ``scan" mode. The survey, hereafter known as the Palomar Distant Cluster Survey (PDCS)...
1995-11-02
2008-11-26
[ "astro-ph" ]
M. Postman (STScI), L. M. Lubin (OCIW), J. E. Gunn (Princeton), J. B. Oke (DAO), J. G. Hoessel (U. Wisconsin), D. P. Schneider (PSU), J. A. Christensen (STScI)
astro-ph/9511015
Hubble Space Telescope Observations of the Lensing Cluster Abell 2218
We present a striking new Hubble Space Telescope (HST) observation of the rich cluster Abell 2218 taken with the Wide-Field and Planetary Camera (WFPC2). HST's restored image quality reveals a sizeable number of gravitationally-lensed features in this cluster, significantly more than had been identified using ground-ba...
1995-11-02
2009-10-28
[ "astro-ph" ]
J.-P. Kneib, R.S. Ellis, I. Smail, W.J. Couch & R.M. Sharples
astro-ph/9511008
A Test of Gamma Ray Burst Recurrence in the BATSE 3B Data Set
We analyse the BATSE 3B catalog using the pair-matching statistic. This statistic counts only the burst pairs which may have originated from the same source, so it is less likely to yield false detections of ``repeating bursts" than the nearest neighbor and correlation function statistics. Even in the ideal case when r...
1995-11-02
2007-05-23
[ "astro-ph" ]
David P. Bennett and Sun Hong Rhie
astro-ph/9511007
The Cluster Abundance in Flat and Open Cosmologies
We use the galaxy cluster X-ray temperature distribution function to constrain the amplitude of the power spectrum of density inhomogeneities on the scale corresponding to clusters. We carry out the analysis for critical density universes, for low density universes with a cosmological constant included to restore spati...
1995-11-01
2015-06-24
[ "astro-ph" ]
Pedro T P Viana and Andrew R Liddle
astro-ph/9510160
The Formation of Dwarf Galaxies in Tidal Debris: A Study of the Compact Group Environment
From R-band images of 42 Hickson compact groups, we present a sample of 47 candidate dwarf galaxies that are associated with the tidal tails and arms in the groups. The candidates, found in 15 tidal features, have R magnitudes and masses (for M/L = 1) in the ranges -16.5 < M_R - 5 log h_{75} < -11.5 and 2x10^6 M_{\odot...
1995-11-01
2009-10-28
[ "astro-ph" ]
Sally D. Hunsberger (PSU), Jane C. Charlton (PSU), and Dennis Zaritsky (UCO/Lick Obs., UCSC)
astro-ph/9511006
Reverberation Mapping and the Disk Wind Model of the Broad Line Region
Using the disk wind model of Murray et al. (1995), we calculate line profiles and frequency-resolved response functions for broad line emission from the surface of an accretion disk in an AGN in the presence of a radiatively driven wind. We find that the combined effects of the shears in the wind and in the disk itself...
1995-11-01
2009-10-28
[ "astro-ph" ]
J. Chiang and N. Murray (CITA)
astro-ph/9511001
Mergers and the Formation of Disk Galaxies in Hierarchically Clustering Universes
New simulations are presented which investigate the formation of smaller groups of galaxies in a CDM like universe. The simulations follow the evolution of dark matter and gas and are performed with an SPH code adapted for the special-purpose hardware GRAPE. The mass resolution in the baryonic component is 5 10^6 Msol,...
1995-11-01
2016-08-30
[ "astro-ph" ]
Matthias Steinmetz
astro-ph/9511005
The Optical Redshift Survey II: Derivation of the Luminosity and Diameter Functions and of the Density Field
We quantify the effects of Galactic extinction on the derived luminosity and diameter functions and on the density field of a redshift sample. Galaxy magnitudes are more affected by extinction than are diameters, although the effect on the latter is more variable from galaxy to galaxy, making it more difficult to quant...
1995-11-01
2009-10-28
[ "astro-ph" ]
Basilio X. Santiago, Michael A. Strauss, Ofer Lahav, Marc Davis, Alan Dressler and John Huchra
astro-ph/9511004
Rotating Winds from Accretion Disks in Cataclysmic Variables: Eclipse Modeling of V347 Puppis
We study the eclipsing nova-like variable V347 Pup by matching its UV emission line profiles in and out of eclipse to synthetic lines using a 3D kinematic and radiation transfer model. Our results support the accretion disk origin of winds in non-magnetic CVs as opposite to the WD origin. Our main point concerns the im...
1995-11-01
2009-10-28
[ "astro-ph" ]
Isaac Shlosman, Peter Vitello, Christopher W. Mauche
astro-ph/9511002
Redshift dependence of clustering in numerical simulations
High resolution $N$-body simulations for variants of the CDM model are used to derive the redshift dependence of galaxy formation and of galaxy correlation functions. The reconstructed power spectra and clustering properties provide a sensible test for the underlying power spectra. We compare our simulations with new r...
1995-11-01
2007-05-23
[ "astro-ph" ]
Volker Mueller
astro-ph/9511003
The HI Content of Spirals. I. Field-Galaxy HI Mass Functions and HI Mass-Optical Size Regression
A standard parametric maximum-likelihood technique is used to determine both the probability distribution over total HI mass $M_{\rm HI}$ and the regression of this quantity on the linear optical diameter $D_{\rm o}$ for field giant spirals (Sa-Sc) from a complete HI-flux-limited data set of these objects. Gaussian and...
1995-11-01
2009-10-28
[ "astro-ph" ]
Jos\'e M. Solanes, Riccardo Giovanelli, and Martha P. Haynes
astro-ph/9510161
Pixel Lensing Experiment toward the M31 Bulge
I demonstrate that one can detect pixel gravitational microlensing events at the rate $\sim 180\ {\rm events}\ {\rm yr}^{-1}$ and that some fraction of events ($\sim 15$) will be good enough to measure time scales at the $20\%$ level if the experiment is carried out toward the central M31 bulge region with a dedicated ...
1995-11-01
2009-10-28
[ "astro-ph" ]
Cheongho Han
astro-ph/9510153
Energetics of star-disc encounters in the non-linear regime
We investigate the response of a circumstellar accretion disc to the fly-by of a perturbing mass on a parabolic orbit. The energy and angular momentum transferred during the encounter are calculated using a reduced three-body method. In almost all close encounters the energy and angular momentum transfer is dominated b...
1995-10-31
2015-06-24
[ "astro-ph" ]
S.M. Hall, C.J. Clarke, J.E. Pringle
astro-ph/9510157
Testing the Strong Equivalence Principle with Mars Ranging Data
The year 1996 will mark the initiation of a number of new space missions to the planet Mars from which we expect to obtain a rich set of data, including spacecraft radio tracking data. Anticipating these events, we have analyzed the feasibility of testing a violation of the strong equivalence principle (SEP) with Earth...
1995-10-31
2007-05-23
[ "astro-ph", "gr-qc" ]
John D. Anderson, Mark Gross, Eunice L. Lau, Kenneth L. Nordtvedt and Slava G. Turyshev
astro-ph/9510154
Hydrodynamic Simulations of Galaxy Formation. II. Photoionization and the Formation of Low Mass Galaxies
Photoionization by the high-redshift ultraviolet radiation background heats low density gas before it falls into dark matter potential wells, and it eliminates the neutral hydrogen and singly ionized helium that dominate cooling of primordial gas at temperatures of $10^4-10^5$K. We investigate the influence of photoion...
1995-10-31
2011-08-17
[ "astro-ph" ]
Anne A. Thoul and David H. Weinberg
astro-ph/9510155
The Mass-to-Light Ratios of the Draco and Ursa Minor Dwarf Spheroidal Galaxies. II. The Binary Population and Its Effect in the Measured Velocity Dispersions of Dwarf Spheroidal Galaxies
We use a large set of radial velocities in the Ursa Minor and Draco dwarf spheroidal galaxies to search for binary stars and to infer the binary frequency. Of the 118 stars in our sample with multiple observations, six are velocity variables with $\chi^2$ probabilities below 0.001. We use Monte Carlo simulations that m...
1995-10-31
2009-10-28
[ "astro-ph" ]
E. Olszewski (Steward Obs), C. Pryor (Physics Dept, Rutgers) and T. Armandroff (NOAO/KPNO)
astro-ph/9510158
Black Holes, Galaxy Formation and the Large-scale Structure of the Universe
A new model for the formation of active galaxies is described. A key feature of this model is the idea that the birth of black holes in the centers of supergiant galaxies is strongly influenced by the large-scale distribution of matter in the universe. This conjecture can successfully explain two observed phenomena: th...
1995-10-31
2007-05-23
[ "astro-ph", "gr-qc" ]
Michael J. West
astro-ph/9510159
Low Dimensional Dynamics in a Pulsating Star
We report the discovery of a low dimensional dynamical system in a 5.5 hr Hubble Space Telescope High Speed Photometer observation of a rapidly oscillating star. The topological description of the phase space orbits is given, as well as a dynamical model which describes the results. This model should motivate theorists...
1995-10-31
2008-02-03
[ "astro-ph", "chao-dyn", "nlin.CD" ]
G. B. Mindlin, P. T. Boyd, J. L. Caaminos, J. A. Nunez
astro-ph/9510156
A Morphological Indicator for Comparing Simulated Cosmological Scenarios with Observations
We propose a morphological multi-scale analysis of large-scale structures obtained by computer simulations and by observations. Structures are obtained at different scales by applying a wavelet transform on the observed and simulated data. Application of a segmentation algorithm allows a quantitative morphological desc...
1995-10-31
2007-05-23
[ "astro-ph" ]
E. Lega(1), A. Bijaoui (1), J.-M. Alimi(2) and H. Scholl (1) ((1) Observatoire de la Cote d'Azur, Nice, France, (2) LAEC, Observatoire de Meudon, France)
astro-ph/9510151
Analysis of Galaxy Morphology and Evolution using the Pointwise Dimension
In this paper we explore the application of the pointwise dimension (PD) analysis as a large-scale structure descriptor to the RC3 catalog of galaxies (de Vaucouleurs et al. 1991). This technique, which originated in the field of fractal geometry (Mandelbrot 1983) and found many applications in non-linear dynamics, is ...
1995-10-30
2009-10-28
[ "astro-ph" ]
Jason S. Best, Jane C. Charlton (Penn State University), Gottfried Mayer-Kress (UIUC)
astro-ph/9510150
Dynamical Modelling of Hot Stellar Systems
Estimation of the distribution function f and potential Phi of hot stellar systems from kinematical data is discussed. When the functional forms of f and Phi are not specified a priori, accurate estimation of either function requires very high quality data: either accurate ``line profiles'' at radii extending well beyo...
1995-10-30
2007-05-23
[ "astro-ph" ]
David Merritt (Rutgers University)
astro-ph/9510149
Modelling Accretion in Protobinary Systems
A method for following fragmentation simulations further in time using smoothed particle hydrodynamics (SPH) is presented. In a normal SPH simulation of the collapse and fragmentation of a molecular cloud, high-density regions of gas that form protostars are represented by many particles with small separations. These h...
1995-10-30
2015-06-24
[ "astro-ph" ]
M.R. Bate, I.A. Bonnell, N.M. Price
astro-ph/9510152
The Influence of Binary Stars on Dwarf Spheroidal Galaxy Kinematics
We have completed a Monte-Carlo simulation to estimate the effect of binary star orbits on the measured velocity dispersion in dwarf spheroidal galaxies. This paper analyses previous attempts at this calculation, and explains the simulations which were performed with mass, period and ellipticity distributions similar t...
1995-10-30
2015-06-24
[ "astro-ph" ]
J.C. Hargreaves (IoA Cambridge), G. Gilmore (IoA), J.D. Annan
astro-ph/9510148
Coronal Gamma Ray Bursts as the sources of Ultra High Energy Cosmic Rays?
I consider the possibility that Ultra High Energy Cosmic Rays are accelerated in Gamma Ray Bursts located in the Galactic corona, thus circumventing the problem raised by Greisen--Zatsepin--Kuz'min cutoff. The acceleration of UHECRs could occur in the pulsars which, in the coronal GRB model, produce them: the same para...
1995-10-30
2016-06-08
[ "astro-ph" ]
Mario Vietri (Osservatorio Astronomico di Roma)
astro-ph/9510147
The Structure of Dark Matter Haloes in Hierarchical Clustering Models
We use a set of large cosmological N-body simulations to study the internal structure of dark matter haloes which form in scale-free models. We find that the radius r_178 corresponding to a mean interior overdensity of 178 accurately delineates the quasi-static halo interior from the surrounding infalling material, in ...
1995-10-30
2015-06-24
[ "astro-ph" ]
Shaun Cole (Durham) and Cedric Lacey (Copenhagen)
astro-ph/9510145
Dynamics of Triaxial Galaxies
Luminous galaxies and their dark halos are likely to have triaxial shapes. The construction of distribution functions for triaxial systems is a hard problem, due to the existence of only one exact integral of motion, the energy $E$. Even so, progress has been made by use of analytic methods for special potentials, nume...
1995-10-27
2008-02-03
[ "astro-ph" ]
P.T. de Zeeuw
astro-ph/9510143
A modified R1 X R1 method for helioseismic rotation inversions
We present an efficient method for two dimensional inversions for the solar rotation rate using the Subtractive Optimally Localized Averages (SOLA) method and a modification of the R1 X R1 technique proposed by Sekii (1993). The SOLA method is based on explicit construction of averaging kernels similar to the Backus-Gi...
1995-10-27
2015-06-24
[ "astro-ph" ]
F.P. Pijpers, M.J. Thompson
astro-ph/9510144
3-D SPH Simulations of HD and MHD Jets
We present fully three-dimensional hydrodynamical and magnetohydrodynamical simulations of supersonic, radiative cooling jets propagating into homogeneous and stratified environments based on Smoothed Particle Hydrodynamics technique.
1995-10-27
2007-05-23
[ "astro-ph" ]
E.M. Gouveia Dal Pino and A.H. Cerqueira
astro-ph/9510146
The 2D Power Spectrum of the Las Campanas Redshift Survey: Detection of Excess Power on 100 h^{-1} Mpc Scales
We have measured the 2 dimensional (2D) power spectrum of the Las Campanas Redshift Survey on scales between 30 and 200 Mpc (q_0=0.5, H_o=100h km sec^{-1} Mpc^{-1}). Such an analysis is more sensitive to structure on scales > 50 Mpc than a full 3 dimensional analysis given the geometry of the survey. We find a strong p...
1995-10-27
2009-06-16
[ "astro-ph" ]
S. D. Landy, S. A. Shectman, H. Lin, R. P. Kirshner, A. A. Oemler and D. Tucker
astro-ph/9510142
Behaviour of Lagrangian Approximations in Spherical Voids
We study the behaviour of spherical Voids in Lagrangian perturbation theories L(n), of which the Zel'dovich approximation is the lowest order solution L(1). We find that at early times higher order L(n) give an increasingly accurate picture of Void expansion. However at late times particle trajectories in L(2) begin to...
1995-10-27
2015-06-24
[ "astro-ph" ]
V. Sahni and S.F. Shandarin
astro-ph/9510139
Scalar-Tensor Cosmological Models
We analyze the qualitative behaviors of scalar-tensor cosmologies with an arbitrary monotonic $\omega(\Phi)$ function. In particular, we are interested on scalar-tensor theories distinguishable at early epochs from General Relativity (GR) but leading to predictions compatible with solar-system experiments. After extend...
1995-10-26
2009-10-28
[ "astro-ph", "gr-qc", "hep-ph" ]
Arturo Serna & Jean-Michel Alimi (LAEC, Observatoire de Meudon, France)
astro-ph/9510140
Constraints on the Scalar-Tensor theories of gravitation from Primordial Nucleosynthesis
We present a detailed calculation of the light element production in the framework of Scalar-Tensor (ST) theories of gravitation. The coupling function \omega has been described by an appropriate form which reproduces all the possible asymptotic behaviors at early times of viable ST cosmological models with a monotonic...
1995-10-26
2011-09-09
[ "astro-ph", "gr-qc", "hep-ph" ]
Arturo Serna & Jean-Michel Alimi (LAEC, Observatoire de Meudon, France)
astro-ph/9510138
Comparison of the dense molecular gas in the LINER galaxy NGC 6764 and in the Wolf-Rayet galaxy NGC 5430
We compare the dense molecular gas content in two barred spiral galaxies, NGC 6764 (classified LINER) and NGC 5430 (a Wolf-Rayet galaxy). We find a significant difference in the proportion of dense molecular gas between the two galaxies. CS(3-2) is detected in NGC 6764 but not in NGC 5430, even though the intensities o...
1995-10-26
2007-05-23
[ "astro-ph" ]
T. Contini, H. Wozniak, E. Davoust and S. Considere
astro-ph/9510141
Formation of High Redshift Objects in a Cosmic String Theory with Hot Dark Matter
Using a modification of the Zel'dovich approximation adapted to hot dark matter, the accretion of such matter onto moving cosmic string loops is studied. It is shown that a large number of $10^{12}M_\odot$ nonlinear objects will be produced by a redshift of $z=4$. These objects could be the hosts of high redshift quasa...
1995-10-26
2015-06-24
[ "astro-ph" ]
R. Moessner (Max Planck Institut fuer Astrophysik, Garching) and R. Brandenberger (Brown Univ.)
astro-ph/9510136
The Neutron Star and Black Hole Initial Mass Function
Using recently calculated models for massive stellar evolution and supernovae coupled to a model for Galactic chemical evolution, neutron star and black hole birth functions (number of neutron stars and black holes as a function of their mass) are determined for the Milky Way Galaxy. For those stars that explode as Typ...
1995-10-26
2011-05-05
[ "astro-ph" ]
F. X. Timmes, S. E. Woosley, and T. A. Weaver
astro-ph/9510137
On Second-order Perturbation Theories of Gravitational Instability in Friedmann-Lemaitre Models
The Eulerian and Lagrangian second-order perturbation theories are solved explicitly in closed forms in $\Omega \neq 1$ and $\Lambda \neq 0$ {}Friedmann-Lema\^{\i}tre models. I explicitly write the second-order theories in terms of closed one-dimensional integrals. In cosmologically interested cases ($\Lambda = 0$ or $...
1995-10-26
2009-10-28
[ "astro-ph" ]
Takahiko Matsubara (The University of Tokyo)
astro-ph/9510131
Colors, Luminosity Function and Counts of Galaxies
Standard models for deep galaxy counts are based on luminosity functions (LF) with relatively flat faint end ($\alpha\sim-1.0$). Galaxy counts in the B--band exceed the prediction of such models by a factor of 2 to more than 5, forcing the introduction of strong luminosity and/or density evolution. Recently Marzke et a...
1995-10-25
2015-06-24
[ "astro-ph" ]
P. Saracco, G. Chincarini and A. Iovino
astro-ph/9510135
Truncation of the Binary Distribution Function in Globular Cluster Formation
We investigate a population of primordial binaries during the initial stage of evolution of a star cluster. For our calculations we assume that equal mass stars form rapidly in a tidally truncated gas cloud, that $\sim10$\% of the stars are in binaries and that the resulting star cluster undergoes an epoch of violent r...
1995-10-25
2009-10-28
[ "astro-ph" ]
E.Vesperini, D.F. Chernoff
astro-ph/9510134
A linear programming approach to inhomogeneous primordial nucleosynthesis
We examine inhomogeneous primordial nucleosynthesis for {\it arbitrary} distributions $f$ of the baryon-to-photon ratio $\eta$, in the limit where neither particle diffusion nor gravitational collapse is important. By discretizing $f(\eta)$ and using linear programming, we show that for a set of $m$ constraints on the ...
1995-10-25
2016-08-30
[ "astro-ph" ]
Richard E. Leonard and Robert J. Scherrer (Ohio State University)
astro-ph/9510132
Equilibrium and Stability of Elliptical Galaxies
Recent work on the equilibrium and stability of ellipsoidal stellar systems is reviewed. The absence of constant-density cores in early-type galaxies implies that chaos and high-order resonances are generic features of the motion in triaxial stellar systems. Bending instabilities are now well understood and may provide...
1995-10-25
2007-05-23
[ "astro-ph" ]
David Merritt and Tema Fridman (Rutgers University)
astro-ph/9510133
The performance of Lagrangian perturbation schemes at high resolution
We present high--spatial resolution studies of the density field as predicted by Lagrangian perturbation approximations up to the third order. The first--order approximation is equivalent to the ``Zel'dovich approximation'' for the type of initial data analyzed. The study is performed for two simple models which allow ...
1995-10-25
2011-05-23
[ "astro-ph" ]
Thomas Buchert, Georgios Karakatsanis, Robert Klaffl, Peter Schiller
astro-ph/9510126
Anisotropy and inhomogeneity of the universe from $\Delta T/T$
A recent paper (Martinez--Gonzalez & Sanz 1995) showed that if the universe is homogeneous but anisotropic, then the small quadrupole anisotropy in the cosmic microwave background radiation implies that the spacetime anisotropy is very small. We point out that more general results may be established, without assuming a...
1995-10-24
2007-05-23
[ "astro-ph" ]
Roy Maartens, George Ellis and William Stoeger
astro-ph/9510127
Search for emission-line galaxies towards nearby voids. Observational data
We present the observational results of our search for emission-line galaxies (ELG) towards nearby voids. In order to find ELG, we started a survey using the IIIa-J objective prism plates from the Hamburg QSO Survey. The plates are digitized and an automatic procedure was applied to select the candidates. Digitized dir...
1995-10-24
2016-08-30
[ "astro-ph" ]
Cristina C. Popescu, Ulrich Hopp, Hans J. Hagen, and Hans Elsaesser
astro-ph/9510128
X-ray analysis and matter distribution in the lens-cluster Abell 2390
We present a deep X-ray ROSAT/HRI observation of the rich cluster-lens Abell 2390 and the analysis of the gas and matter distribution in the cluster. The X-ray centroid coincides with the location of the central cD galaxy, and the core appears to be dominated by a massive cooling flow, one of the strongest ones ever st...
1995-10-24
2008-02-03
[ "astro-ph" ]
M. Pierre, J.F. Le Borgne, G. Soucail, J.P. Kneib
astro-ph/9510125
Hydrodynamics of Stellar Mergers and the Formation of Blue Stragglers
The hydrodynamics of stellar collisions and mergers is discussed in the context of blue straggler formation. Emphasis is placed on the very important question of hydrodynamic mixing during the merger process. Recent results of three-dimensional hydrodynamic calculations suggest that the merger remnants produced by stel...
1995-10-24
2007-05-23
[ "astro-ph" ]
Frederic A. Rasio (MIT)
astro-ph/9510130
On the Uncertainty in X-Ray Cluster Mass Estimates
We study the uncertainty in galaxy cluster mass estimates derived from X-ray data assuming hydrostatic equilibrium (HE) for the intra cluster gas. Using a Monte-Carlo procedure we generate a general class of mass models allowing very massive clusters. We then compute the corresponding temperature profiles via the HE eq...
1995-10-24
2007-05-23
[ "astro-ph" ]
C. Balland and A. Blanchard
astro-ph/9510129
The Angular Power Spectrum of BATSE 3B Gamma-Ray Burst
We compute the angular power spectrum C_l from the BATSE 3B catalog of 1122 gamma-ray bursts, and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropies fr...
1995-10-24
2009-10-07
[ "astro-ph" ]
Max Tegmark, Dieter Hartmann, Michael Briggs & Charles Meegan
astro-ph/9510119
Comparison of Optical, Radio, and Acoustical Detectors for Ultrahigh-Energy Neutrinos
For electromagnetic cascades induced by electron-neutrinos in South Pole ice, the effective volume per detector element (phototube, radio antenna, or acoustic transducer) as a function of cascade energy is estimated, taking absorption and scattering into account. A comparison of the three techniques shows that the opti...
1995-10-23
2011-05-23
[ "astro-ph" ]
P. B. Price (Dept. of Physics, University of California, Berkeley)
astro-ph/9510113
The Dynamics of Galactic Warps
Large-scale warps in the outer parts of spiral galaxy discs have been observed for almost forty years, but their origin remains obscure. We review the dynamics of warped galaxy discs. We identify several mechanisms that could excite warps, all involving the gravitational interaction between the disc and the dark-matter...
1995-10-23
2007-05-23
[ "astro-ph" ]
Robert W. Nelson and Scott Tremaine
astro-ph/9510117
Small Scale Cosmological Perturbations: An Analytic Approach
Through analytic techniques verified by numerical calculations, we establish general relations between the matter and cosmic microwave background (CMB) power spectra and their dependence on cosmological parameters on small scales. Fluctuations in the CMB, baryons, cold dark matter (CDM), and neutrinos receive a boost a...
1995-10-23
2009-07-22
[ "astro-ph" ]
Wayne Hu (IAS, Princeton) and Naoshi Sugiyama (Kyoto)
astro-ph/9510122
Detection of C2, CN, and NaID absorption in the AGB remnant of HD56126
We present the detection of molecular absorption lines in the optical spectrum of the post-AGB star HD56126. The C2 Phillips A^{1}\Pi_{u}-X^{1}\Sigma^{+}_{g} (1,0), (2,0), and (3,0); Swan d^{3}\Pi_{g}-a^{3}\Pi_{u} (0,0) and (1,0); and CN Red system A^{2}\Pi-X^{2}\Sigma^{+} (1,0), (2,0), (3,0), and (4,0) bands have been...
1995-10-23
2007-05-23
[ "astro-ph" ]
Eric J. Bakker, L.B.F.M. Waters, Henny J.G.L.M. Lamers, Norman R. Trams, Frank L.A. Van der Wolf
astro-ph/9510121
Time resolved spectroscopy of the post-AGB star HD56126
We have investigated the report of Tamura and Takeuti that the Halpha line of the F-type post-AGB star HD56126 is variable on time scales of minutes. To this end, HD56126 was observed on two occasions with the William Herschel Telescope. Seventeen, respectively thirty spectra were taken within time span of 1.5 hours in...
1995-10-23
2015-06-24
[ "astro-ph" ]
Rene D. Oudmaijer, Eric J. Bakker
astro-ph/9510123
Motion and Ionization Equilibrium of Hydrogen Atoms in Superstrong Magnetic Field
We study the effects of finite proton mass on the energy levels of hydrogen atoms moving transverse to a superstrong magnetic field $B$ with generalized pseudomomentum $K_\perp$. Field strengths of order $B\sim 10^{12}$ Gauss are typically found on the surfaces of neutron stars, but we also study the regime $B\go B_{cr...
1995-10-23
2008-11-26
[ "astro-ph", "atom-ph" ]
Dong Lai (Caltech) and Edwin E. Salpeter (Cornell)
astro-ph/9510120
The velocity gradient in the pseudo-photosphere of the peculiar supergiant HD101584
In this paper preliminary results are presented based on a study of the low and high resolution ultraviolet spectrum of the peculiar supergiant (post-AGB star) HD101584. By a comparison of the low resolution spectrum (1200-3200ang) with standard stars, the star is classified as an A7I, indicating an effective temperatu...
1995-10-23
2007-05-23
[ "astro-ph" ]
Eric J. Bakker
astro-ph/9510114
The Distance to IC 10 from Near-Infrared Observations of Cepheids
We have measured the distance to the Local Group dwarf irregular galaxy IC 10 from near-infrared $JHK$ observations of Cepheids. The reddening-corrected distance modulus is $24.57\pm0.21$ mag or $0.82\pm 0.08$ Mpc. This distance lies at the short end of the range of previous estimates, and is significantly more accurat...
1995-10-23
2009-10-28
[ "astro-ph" ]
C.D. Wilson, D.L. Welch, I.N. Reid, A. Saha, and J. Hoessel
astro-ph/9510124
Hydrogen Molecules In Superstrong Magnetic Field: II. Excitation Levels
We study the energy levels of H$_2$ molecules in a superstrong magnetic field ($B\go 10^{12}$ G), typically found on the surfaces of neutron stars. The interatomic interaction potentials are calculated by a Hartree-Fock method with multi-configurations assuming electrons are in the ground Landau state. Both the aligned...
1995-10-23
2009-10-28
[ "astro-ph", "atom-ph" ]
Dong Lai (Caltech) and Edwin E. Salpeter (Cornell)
astro-ph/9510118
Three-body crystallization diagrams and the cooling of white dwarfs
The 3-body crystallization diagrams of C/O/Ne ionic mixtures characteristic of white dwarf interiors are examined within the framework of the density-functional theory of freezing. The crystallization process is described more accurately than in former calculations where the three-component system was treated as an eff...
1995-10-23
2007-05-23
[ "astro-ph" ]
Laurent Segretain (Centre de recherche Astronomique de Lyon, UMR 142 du CNRS, France)
astro-ph/9510116
X-ray spectra from convective photospheres of neutron stars
We present first results of modeling convective photospheres of neutron stars. We show that in photospheres composed of the light elements convection arises only at relatively low effective temperatures (< 3-5*10^4 K), whereas in the case of iron compositon it arises at < 3*10^ K. Convection changes the depth dependenc...
1995-10-23
2008-02-03
[ "astro-ph" ]
V.E. Zavlin, G.G. Pavlov, Yu.A. Shibanov, F.J. Rogers and C.A. Iglesias
astro-ph/9510115
The MHD Kelvin-Helmholtz Instability: A Two-Dimensional Numerical Study
Using a new numerical code we have carried out two-dimensional simulations of the nonlinear evolution of unstable sheared magnetohydrodynamic flows. We considered two cases: a strong magnetic field (Alfven Mach number, M_a = 2.5) and a weak field (M_a =5). Each flow rapidly evolves until it reaches a nearly steady cond...
1995-10-23
2009-10-28
[ "astro-ph" ]
Adam Frank, T. W. Jones, Dongsu Ryu, Joseph B. Gaalaas
astro-ph/9510112
The Size and Nature of Lyman alpha Forest Clouds Probed by QSO Pairs and Groups
We describe a robust Bayesian statistical method for determining Lyman alpha forest cloud sizes in spherical and in thin disk geometries, using absorption in adjacent sightlines toward closely separated QSO pairs and groups, apply this method to the available data, and discuss implications of our results for models of ...
1995-10-20
2009-10-28
[ "astro-ph" ]
Yihu Fang (Columbia), Robert C. Duncan (Univ of Texas), Arlin P. S. Crotts (Columbia) and Jill Bechtold (Steward Observatory)
astro-ph/9510107
Distributions of Peak Flux and Duration for Gamma-Ray Bursts
Many of the important conclusions about Gamma-Ray Bursts follow from the distributions of various quantities such as peak flux or duration. We show that for astrophysical transients such as bursts, multiple selection thresholds can lead to various forms of data truncation, which can strongly affect the distributions ob...
1995-10-20
2009-10-28
[ "astro-ph" ]
Vahe Petrosian, Theodore T. Lee (Stanford University)
astro-ph/9510102
Producing Mega-pixel CMB Maps from Differential Radiometer Data
A major goal of cosmology is to obtain sensitive, high resolution maps of the Cosmic Microwave Background (CMB) anisotropy. Such maps, as would be produced by the recently proposed Microwave Anisotropy Probe (MAP), will contain a wealth of primary information about conditions in the early universe. To mitigate systemat...
1995-10-20
2009-10-28
[ "astro-ph" ]
Edward L. Wright, Gary Hinshaw and Charles L. Bennett
astro-ph/9510104
The MACHO Project Dark Matter Search
We provide a status report on our search for dark matter in our Galaxy in the form of massive compact halo objects (or Machos), using gravitational microlensing of background stars. This search uses a very large format CCD camera on the dedicated 1.27m telescope at Mt.~Stromlo, Australia, and has been taking data for a...
1995-10-20
2007-05-23
[ "astro-ph" ]
D.P. Bennett, C. Alcock, R.A. Allsman, T.S. Axelrod, K.H. Cook, K.C. Freeman, K. Griest, S.L. Marshall, B.A. Peterson, M.R. Pratt, P.J. Quinn, A.W. Rodgers, C.W. Stubbs, W. Sutherland (The MACHO Collaboration)
astro-ph/9510106
Spectral line identification of the ultraviolet spectrum of the peculiar post-AGB star HD101584 (F0Iape)
The high-resolution (R = 10^4) near-ultraviolet IUE spectrum of the peculiar post Asymptotic Giant Branch (post-AGB) supergiant HD101584 (F0Iape) has been analyzed. In the wavelength range between 2500 and 3000ang, 291 out of 332 absorption features are identified. The main contribution comes from FeII, CrII and MnII. ...
1995-10-20
2008-02-03
[ "astro-ph" ]
Eric J. Bakker
astro-ph/9510108
Voids in Real Space and in Redshift Space
Using two-dimensional numerical simulations of gravitational clustering, with initial power spectra of a power-law form with index n, we compare the properties of voids in real space to their properties in redshift space. Both the void probability function (VPF) and the underdense probability function (UPF) are enhance...
1995-10-20
2009-10-28
[ "astro-ph" ]
Barbara Ryden (Ohio State U.) and Adrian Melott (U. of Kansas)
astro-ph/9510111
The Frequency Function of Elliptical Galaxy Intrinsic Shapes
We present fully nonparametric estimates of the frequency function of elliptical galaxy intrinsic shapes under the axisymmetric and triaxial hypotheses. If elliptical galaxies are assumed to be oblate or prolate, the frequency function of intrinsic shapes is negative for axis ratios near unity due to the lack of appare...
1995-10-20
2009-10-28
[ "astro-ph" ]
Benoit Tremblay and David Merritt (Rutgers University)
astro-ph/9510109
Can the lack of symmetry in the COBE/DMR maps constrain the topology of the universe?
Although the cubic T^3 "small universe" has been ruled out by COBE/DMR results as an interesting cosmological model, we still have the possibility of living in a universe with a more anisotropic topology such as a rectangular T^3 "small universe" with one or two of its dimensions significantly smaller than the present ...
1995-10-20
2009-10-28
[ "astro-ph", "gr-qc" ]
Angelica de Oliveira-Costa, George F. Smoot, Alexei A. Starobinsky
astro-ph/9510110
Stellar and dynamical evolution within triple systems
About 5-15% of stellar systems are at least triple. About 1% of systems with a primary of $\tgs 1 \Mscun$ are triple with a {\it longer} peri od that is less than 30y, and so may in principle be capable of Roche-lobe overflow in both the inner and the outer orbits, at different times. We discuss possible evolutionary p...
1995-10-20
2007-05-23
[ "astro-ph" ]
P.P. Eggleton, L.G. Kiseleva
astro-ph/9510105
The Intrinsic Shapes of Stellar Systems
I compute the estimated distribution function f(q) for the apparent axis ratio q of various types of stellar systems, using a nonparametric kernel method. I then invert f(q) to find the distribution of intrinsic axis ratios, using two different hypotheses: first, that the stellar systems are all oblate, and second, tha...
1995-10-20
2009-10-28
[ "astro-ph" ]
Barbara S. Ryden
astro-ph/9510098
Planetary Nebulae as Probes of Dark Matter in NGC 3384
We have obtained radial velocities of 68 planetary nebulae surrounding the SB0 galaxy NGC 3384 in the Leo I group, using the CTIO 4 m telescope and the Rutgers Fabry-Perot interferometer. The PN system exhibits a well-ordered rotation field aligned with the photometric axes of the galaxy. The rotation curve is flat fro...
1995-10-19
2009-10-28
[ "astro-ph" ]
Benoit Tremblay, David Merritt and T. B. Williams (Rutgers)
astro-ph/9510097
Circumstellar molecular line absorption and emission in the optical spectra of post-AGB stars
We present a list of post-AGB stars showing molecular line absorption and emission in the optical spectrum. Two objects show CH+, one in emission and one in absorption, and ten stars show C2 and CN in absorption. The Doppler velocities of the C2 lines and the rotational temperatures indicate that the line forming regio...
1995-10-19
2009-10-28
[ "astro-ph" ]
Eric J. Bakker, Henny J.G.L.M. Lamers, L.B.F.M. Waters, Ton Schoenmaker
astro-ph/9510096
Dynamical Families in the Galacti Globular Cluster System
The Halo Galactic Globular Clusters (GCs) lying inside the solar circle (\inn, \r $< 8 Kpc$, \feh$<-0.8$) are shown to keep no record of the strong correlation between GC absolute integrated magnitudes and core parameters (concentration and central density) clearly detected for the Halo GCs lying outside this circle (\...
1995-10-19
2015-06-24
[ "astro-ph" ]
M. Bellazzini, E. Vesperini, F. Fusi Pecci and F.R. Ferraro
astro-ph/9510094
Model Atmospheres for Low Field Neutron Stars
We compute model atmospheres and emergent spectra for low field (B<10^10 G) neutron stars, using new opacity and equation of state data from the OPAL project. These computations, incorporating improved treatments of flux transport and convective stability, provide spectra for hydrogen, solar abundance and iron atmosphe...
1995-10-19
2009-10-28
[ "astro-ph" ]
Mohan Rajagopal and Roger Romani
astro-ph/9510100
Kinematics of the Broad Emission Line Region in NGC 5548
We derive both total flux and velocity-resolved response functions for the CIV 1549 emission line from the data obtained in the 1993 NGC 5548 monitoring campaign. These response functions imply: 1.) the emission region stretches from inside 1 lt-d to outside 10 lt-d, and is probably better described as round than flat;...
1995-10-19
2009-10-28
[ "astro-ph" ]
Christine Done (Durham University) and Julian Krolik (Johns Hopkins University)
astro-ph/9510093
HST Observations of the Luminous IRAS Source FSC10214+4724: A Gravitationally Lensed Infrared Quasar
We present an image of the redshift 2.3 IRAS source FSC10214+4724 at 0.8 microns obtained with the HST WFPC2 Planetary Camera. The source appears as an unresolved (< 0.06") arc 0.7" long, with significant substructure along its length. The arc is centered near an elliptical galaxy 1.18" to the north. An unresolved comp...
1995-10-19
2009-10-28
[ "astro-ph" ]
Peter R. Eisenhardt (JPL/Caltech), Lee Armus, David W. Hogg, B. T. Soifer, G. Neugebauer (Caltech), Michael W. Werner (JPL/Caltech)
astro-ph/9510099
Microlensing rates from self-consistent galactic models
We study different models of dark matter distribution for the halo of our galaxy. In particular, we consider Eddington and King-Michie models, which [C[C, which include anisotropy in the velocity space, and compute in a self-consistent way the amount of dark matter present in the halo. Assuming that the dark matter is ...
1995-10-19
2009-10-28
[ "astro-ph" ]
F. De Paolis, G. Ingrosso and Ph. Jetzer
astro-ph/9510095
Morphological classification and structural parameters for early-type galaxies in the Coma cluster
We present the results of an isophotal shape analysis of three samples of galaxies in the Coma cluster. Quantitative morphology, together with structural and photometric parameters, is given for each galaxy. Special emphasis has been placed on the detailed classification of early-type galaxies. The three samples are:...
1995-10-19
2007-05-23
[ "astro-ph" ]
S. Andreon, E. Davoust, R. Michard, J.-L. Nieto, P. Poulain
astro-ph/9510101
The metallicity distribution of G dwarfs in the solar neighbourhood
We derive a new metallicity distribution of G dwarfs in the solar neighbourhood, using uvby photometry and up-to-date parallaxes. Our distribution comprises 287 G dwarfs within 25 pc from the Sun, and differs considerably from the classic solar neighbourhood distribution of Pagel & Patchett and Pagel by having a promin...
1995-10-19
2015-06-24
[ "astro-ph" ]
Helio J. Rocha-Pinto and Walter J. Maciel (IAG/USP)
astro-ph/9510092
Spiral Structure In The Circum-nuclear Disk At The Center Of The Galaxy NGC 4258
Observations of line emission from water masers near the center of the galaxy NGC 4258 have recently provided compelling evidence for rotating disk of gas, viewed nearly edge-on, surrounding a massive black hole (Miyoshi etal. 1995). We show that the disk is only marginally stable to radial perturbations - a stabilit...
1995-10-18
2009-10-28
[ "astro-ph" ]
Eyal Maoz
astro-ph/9510089
The Nature of the Dark Matter
We review some recent determinations of the amount of dark matter on galactic and larger scales, with special attention to the dark matter in the Milky Way. We then briefly review the motivation for and basic physics of several dark matter candidates, and then go into more depth for two candidates, the neutralino from ...
1995-10-18
2007-05-23
[ "astro-ph", "hep-ph" ]
Kim Griest