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|Formation of inner rings in 3D potentials of barred galaxies|
In a 3D analytic potential we find the families of periodic orbits thatsupport the formation of inner rings. These are families at highenergies, between the inner radial ultraharmonic 4:1 (iUHR) resonanceand corotation, influenced by the 4:1, 6:1 and 8:1 resonances. The innerrings they support are mainly ovals and polygons with `corners' on thebar minor axis, on its sides, which correspond to morphologies oftenseen in real galaxies like NGC 6782 and IC 4290. We also investigate theconditions under which less probable shapes of rings may be supported byorbits at the region. Such rings include pentagonal features (NGC 3367)and hexagons with cusps on the major axis of the bar and two sidesparallel to it (NGC 7020).
|On the 3D dynamics and morphology of inner rings|
We argue that inner rings in barred spiral galaxies are associated withspecific 2D and 3D families of periodic orbits located just beyond theend of the bar. These are families located between the inner radialultraharmonic 4:1 resonance and corotation. They are found in the upperpart of a type-2 gap of the x1 characteristic, and can account for theobserved ring morphologies without any help from families of thex1-tree. Due to the evolution of the stability of all these families,the ring shapes that are favoured are mainly ovals, as well as polygonswith `corners' on the minor axis, on the sides of the bar. On the otherhand, pentagonal rings, or rings of the NGC 7020-type hexagon, should beless probable. The orbits that make the rings belong in their vastmajority to 3D families of periodic orbits and orbits trapped aroundthem.
|FLASH redshift survey - I. Observations and catalogue|
The FLAIR Shapley-Hydra (FLASH) redshift survey catalogue consists of4613 galaxies brighter than bJ= 16.7 (corrected for Galacticextinction) over a 700-deg2 region of sky in the generaldirection of the Local Group motion. The survey region is a70°× 10° strip spanning the sky from the ShapleySupercluster to the Hydra cluster, and contains 3141 galaxies withmeasured redshifts. Designed to explore the effect of the galaxyconcentrations in this direction (in particular the Supergalactic planeand the Shapley Supercluster) upon the Local Group motion, the 68 percent completeness allows us to sample the large-scale structure betterthan similar sparsely-sampled surveys. The survey region does notoverlap with the areas covered by ongoing wide-angle (Sloan or 2dF)complete redshift surveys. In this paper, the first in a series, wedescribe the observation and data reduction procedures, the analysis forthe redshift errors and survey completeness, and present the surveydata.
|A Dust-penetrated Classification Scheme for Bars as Inferred from Their Gravitational Force Fields|
The division of galaxies into ``barred'' (SB) and ``normal'' (S) spiralsis a fundamental aspect of the Hubble galaxy classification system. This``tuning fork'' view was revised by de Vaucouleurs, whose classificationvolume recognized apparent ``bar strength'' (SA, SAB, SB) as acontinuous property of galaxies called the ``family.'' However, the SA,SAB, and SB families are purely visual judgments that can have littlebearing on the actual bar strength in a given galaxy. Until veryrecently, published bar judgments were based exclusively on blue lightimages, where internal extinction or star formation can either mask abar completely or give the false impression of a bar in a nonbarredgalaxy. Near-infrared camera arrays, which principally trace the oldstellar population in both normal and barred galaxies, now facilitate aquantification of bar strength in terms of their gravitationalpotentials and force fields. In this paper, we show that the maximumvalue, Qb, of the ratio of the tangential force to the meanaxisymmetric radial force in a barred disk galaxy is a quantitativemeasure of the strength of a bar. Qb does not measure barellipticity or bar shape but rather depends on the actual forcing due tothe bar embedded in its disk. We show that a wide range of true barstrengths characterizes the category ``SB,'' while the de Vaucouleurscategory ``SAB'' corresponds to a narrower range of bar strengths. Wepresent Qb values for 36 galaxies, and we incorporate our barclasses into a dust-penetrated classification system for spiralgalaxies.
|An Inner Ring and the Microlensing toward the Bulge|
All current bulge-disk models for the inner Galaxy fall short ofreproducing self-consistently the observed microlensing optical depth bya factor of 2 (>2 σ). We show that the least mass-consuming wayto increase the microlensing optical depth is to add density roughlyhalfway between the observer and the highest microlensing sourcedensity. We present evidence for the existence of such a densitystructure in the Galaxy: an inner ring, a standard feature of barredgalaxies. Judging from data on similar rings in external galaxies, aninner ring can contribute more than 50% of a pure bulge-disk model tothe microlensing optical depth. We may thus eliminate the need for asmall viewing angle of the bar. The influence of an inner ring on theevent duration distribution, for realistic viewing angles, would be toincrease the fraction of long-duration events toward Baade's window. Thelongest events are expected toward the negative-longitude tangent pointat l~-22°. A properly sampled event duration distribution towardthis tangent point would provide essential information about viewingangle and elongation of the overall density distribution in the innerGalaxy.
|An Optical, Near-Infrared, and Kinematic Study of Four Early-Type Resonance Ring Galaxies|
We present optical and near-infrared surface photometry of fourearly-type galaxies considered to have resonance ring phenomena on thebasis of morphology. We also present kinematics and rotation curves forthree of the galaxies. The four galaxies are exceptional examples ofresonance ring galaxies, and from these observations we derive thecharacteristic light distributions, the colors of the rings, and thenear-infrared disk mass-to-light ratios. We also deproject the galaxiesto examine intrinsic ring shapes and bar/ring alignments. From models ofthe rotation curves, we compute the Lindblad precession frequencies toexamine resonance locations in the disks of the galaxies. Under theassumption that the outer rings and pseudorings seen in these galaxiesare linked to the outer Lindblad resonance, we find that the inner ringsof the sample galaxies lie near the inner 4:1 resonance and that thesharp ends of the bars lie on average at only 0.65 times the predictedradius of corotation.
|Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies|
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com
|The Catalog of Southern Ringed Galaxies|
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
|Integrated photometric properties of early type ringed galaxies|
In order to elucidate the structure and evolution of barred and ovalgalaxies, over 300 of the more than 1000 galaxies in the current versionof the Catalog of Southern ringed Galaxies are subclassified intoring/pseudoring categories. Photoelectric multicolor photometry of 29ringed galaxies showing outer rings and pseudorings of the suspectedouter Lindblad resonance types reveals nothing unusual about the globalstar formation rates. The galaxies have relatively normal colors fortheir type but slightly lower than average surface brightnesses. It isdemonstrated that integrated colors (V-R)T and(V-I)T can be derived reasonably well by using standard RC2color curves originally designed for (B-V)T and(U-B)T determinations. A comparison between the presentintegrated photoelectric parameters and those in the ESO-LV data basereveals good agreement on B-band magnitudes but not total R-bandmagnitudes or B-R colors.
|The supergalactic plane redshift survey|
Redshift measurements, about 1000 of which are new, are presented for1314 galaxies in a survey toward the apex of the large-scale streamingflow for ellipticals. The velocity histogram shows that the excess ingalaxy number counts in this area is due to a substantial concentrationof galaxies with discrete peaks at V about 3000 km/s and V about 4500km/s. After correction for the sampling function, the centroid of thedensity distribution is found to be near V about 4500 km/s.Normalization to the more extensive SSRS survey, which was selected bythe same criteria, shows that the region studied contains a considerableoverdensity of galaxies from 2000 to 6000 km/s. This result is in goodagreement with the 'great attractor' model suggested by Lynden-Bell etal. (1988) which attributes the peculiar motions of elliptical galaxiesover a large region of space to an extensive mass overdensity whichincludes the Hydra-Centaurus and Pavo-Indus superclusters. The centroidof the density enhancement is also consistent with new data by Dresslerand Faber (1990) of peculiar motions of elliptical and spiral galaxies,both of which show a zero crossing of the Hubble line at approximately4500-5000 km/s.
|The outer Lindblad resonance and the morphology of early type disk galaxies|
CCD images and color index maps of 22 galaxies from the Catalog ofSouthern Ringed Galaxies (CSRG) are used to examine distinct categoriesof the morphology of outer rings and pseudorings in SB and SAB galaxies,which bear a remarkable resemblance to the gaseous rings which developednear the outer Lindblad resonance in n-body models of barred spirals. Ina class of rings where the arms wind about 180 deg with respect to theends of a bar or oval, nine out of 11 examples display blue nuclei orcircumnuclear rings in a B-I color index map. This contrasts with aclass where the arms wind about 270 deg with respect to the ends of abar or oval, for which only 3 out of 11 examples display nuclear starformation. A similar correlation regarding the presence or absence of aclear dust lane pattern is found within the region of a bar or inneroval. Images of eight additional CSRG galaxies which displaymorphological details of special interest are presented.
|The plane W(Na I) X W(Mg I) - Effects of interstellar Na I in a sample of southern galaxies|
Galaxy spectra from a subsample of the Southern Sky Redshift Survey databank were used to study the equivalent width plane for the lines Na Ilambda 5893 A vs Mg I lambda 5175 A. An estimate of how important thecontribution of the interstellar gas for the sodium line is compared tothat of the stellar population. The sample is made up of galaxies withmorphological types from E to Sc and are distributed up to radialvelocities of 25,000 km/s, most of them smaller than 15,000 km/s. Mostearly type galaxies with dust lanes, particularly nearly edge-on So's,present an enhancement of the Na I line. Inclined spiral galaxies tendto present enhanced Na I with respect to face-on spirals. This tendency,previously found in a smaller sample of galaxies limited to V equal toor less than 6000 km/s, is now confirmed for more distant ones. In thelarge velocity sample it shows the global bulge rather than the verynucleus; the persistence of the effect suggests that the scale height ofthe gas layer in the central disk can reach a considerable fraction ofthe bulge radius.
|A wide angle redshift survey of the Hydra-Centaurus region|
Spectroscopic observations of 266 galaxies in the Hya-Cen region arereported. Redshift data obtained at 350-700 nm with dispersion 21 nm/mmusing the UNIT spectrograph and RPCS detector on the 1.9-m RadcliffeReflector telescope at SAO during March 1985, May 1986, and March 1987are presented in tables and graphs and briefly characterized. It isshown that the Hya supercluster is separated from the Cen superclusterby a large void at right ascension 11 h 40 min, declination -35 deg, andradial velocity 5200 km/sec; a bridge of galaxies at velocity about 3200km/sec connects the two superclusters.
|A catalogue of Seyfert galaxies.|
|The Centaurus-Hydra supercluster region. II|
In this paper, 139 redshifts obtained in the region of theCentaurus-Hydra supercluster are presented. These data, combined withthe radial velocities reported in an earlier paper, are used in apreliminary investigation of the spatial distribution of galaxies in thesurroundings of the Centaurus cluster. Attention is focused on twoparticular regions of the sky for which we have nearly complete redshiftsamples of galaxies brighter than blue magnitude 15.0. From the analysisof the spatial distribution of galaxies in these two regions, it isfound that the system of galaxies associated with the Centaurus clusterextends northeastward, and that the complexes of Centaurus and Hydra maywell be considered as separate superclusters.
|New southern galaxies with active nuclei|
A list of AGN candidates, identified from optical spectra taken as partof an ongoing redshift survey of southern galaxies, is presented. Theidentification, coordinates, morphological type, measured heliocentricradial velocity, and proposed emission type are given for the galaxiesshowing evidence of nonstellar nuclear activity. Using standarddiagnostics, several new Seyferts and low-ionization nuclear-emissionregions (LINERs) are identified among the emission-line galaxiesobserved.
|Static properties of galaxies in the Shapley-Centaurus cluster. I - The catalogue|
A catalogue of the positions, sizes, orientations, ellipticities, andmorphological descriptions of 127 galaxies measured in the Southern SkySurvey Field 444 is given. The measurement errors, both internal andexternal, are discussed.
|Southern Galaxy Catalogue.|
|Redshifts in Klemola 27|
Observational data for galaxies in the galaxy cluster Klemola 27gathered over the last few years are presented. These are mostly newredshifts and further, accurate coordinates and morphological types fora large number of 'prominent' galaxies in the ESO/SRC-Survey fields 444and 445. A few preliminary H I radial velocities are also reported. Thedata available for this cluster are briefly discussed.
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