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On the Relation between Circular Velocity and Central Velocity Dispersion in High and Low Surface Brightness Galaxies
In order to investigate the correlation between the circular velocityVc and the central velocity dispersion of the spheroidalcomponent σc, we analyzed these quantities for a sampleof 40 high surface brightness (HSB) disk galaxies, eight giant lowsurface brightness (LSB) spiral galaxies, and 24 elliptical galaxiescharacterized by flat rotation curves. Galaxies have been selected tohave a velocity gradient <=2 km s-1 kpc-1 forR>=0.35R25. We used these data to better define theprevious Vc-σc correlation for spiralgalaxies (which turned out to be HSB) and elliptical galaxies,especially at the lower end of the σc values. We findthat the Vc-σc relation is described by alinear law out to velocity dispersions as low as σc~50km s-1, while in previous works a power law was adopted forgalaxies with σc>80 km s-1. Ellipticalgalaxies with Vc based on dynamical models or directlyderived from the H I rotation curves follow the same relation as the HSBgalaxies in the Vc-σc plane. On the otherhand, the LSB galaxies follow a different relation, since most of themshow either higher Vc or lower σc withrespect to the HSB galaxies. This argues against the relevance of baryoncollapse to the radial density profile of the dark matter halos of LSBgalaxies. Moreover, if the Vc-σc relation isequivalent to one between the mass of the dark matter halo and that ofthe supermassive black hole, then these results suggest that the LSBgalaxies host a supermassive black hole (SMBH) with a smaller masscompared to HSB galaxies with an equal dark matter halo. On the otherhand, if the fundamental correlation of SMBH mass is with the halocircular velocity, then LSB galaxies should have larger black holemasses for a given bulge dispersion. Elliptical galaxies withVc derived from H I data and LSB galaxies were not consideredin previous studies.Based on observations made with European Southern Observatory telescopesat the Paranal Observatory under programs 67.B-0283, 69.B-0573, and70.B-0171.
| Rotational Widths for Use in the Tully-Fisher Relation. I. Long-Slit Spectroscopic Data
We present new long-slit Hα spectroscopy for 403 noninteractingspiral galaxies, obtained at the Palomar Observatory 5 m Hale telescope,which is used to derive well-sampled optical rotation curves. Becausemany of the galaxies show optical emission features that aresignificantly extended along the spectrograph slit, a technique wasdevised to separate and subtract the night sky lines from the galaxyemission. We exploit a functional fit to the rotation curve to identifyits center of symmetry; this method minimizes the asymmetry in thefinal, folded rotation curve. We derive rotational widths using bothvelocity histograms and the Polyex model fit. The final rotational widthis measured at a radius containing 83% of the total light as derivedfrom I-band images. In addition to presenting the new data, we use alarge sample of 742 galaxies for which both optical long-slit and radioH I line spectroscopy are available to investigate the relation betweenthe H I content of the disks and the extent of their rotation curves.Our results show that the correlation between those quantities, which iswell established in the case of H I-poor galaxies in clusters, ispresent also in H I-normal objects: for a given optical size, starformation can be traced farther out in the disks of galaxies with largerH I mass.
| Circumnuclear Dust in Nearby Active and Inactive Galaxies. II. Bars, Nuclear Spirals, and the Fueling of Active Galactic Nuclei
We present a detailed study of the relation between circumnuclear dustmorphology, host-galaxy properties, and nuclear activity in nearbygalaxies. We use our sample of 123 nearby galaxies withvisible-near-infrared color maps from the Hubble Space Telescope tocreate well-matched, ``paired'' samples of 28 active and 28 inactivegalaxies, as well as 19 barred and 19 unbarred galaxies, that have thesame host-galaxy properties. Comparison of the barred and unbarredgalaxies shows that grand-design nuclear dust spirals are found only ingalaxies with a large-scale bar. These nuclear dust spirals, which arepresent in approximately one-third of all barred galaxies, also appearto be connected to the dust lanes along the leading edges of thelarge-scale bars. Grand-design nuclear spirals are more common thaninner rings, which are present in only a small minority of the barredgalaxies. Tightly wound nuclear dust spirals, in contrast, show a strongtendency to avoid galaxies with large-scale bars. Comparison of theactive galactic nuclei (AGNs)and inactive samples shows that nucleardust spirals, which may trace shocks and angular momentum dissipation inthe interstellar medium, occur with comparable frequency in both activeand inactive galaxies. The only difference between the active andinactive galaxies is that several inactive galaxies appear to completelylack dust structure in their circumnuclear region, while none of theAGNs lack this structure. The comparable frequency of nuclear spirals inactive and inactive galaxies, combined with previous work that finds nosignificant difference in the frequency of bars or interactions betweenwell-matched active and inactive galaxies, suggests that no universalfueling mechanism for low-luminosity AGNs operates at spatial scalesgreater than a ~100 pc radius from the galactic nuclei. The similaritiesof the circumnuclear environments of active and inactive galaxiessuggest that the lifetime of nuclear activity is less than thecharacteristic inflow time from these spatial scales. Anorder-of-magnitude estimate of this inflow time is the dynamicaltimescale. This sets an upper limit of several million years to thelifetime of an individual episode of nuclear activity.Based on observations with the NASA/ESA Hubble Space Telescope obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS5-26555.
| Do bulges of early- and late-type spirals have different morphology?
We study HST/NICMOS H-band images of bulges of two equal-sized samplesof early- (TRC3 <= 3) and late-type spiral (mainly Sbc-Sc)galaxies matched in outer disk axis ratio. We find that bulges oflate-type spirals are more elongated than their counterparts inearly-type spirals. Using a KS-test we find that the two distributionsare different at the 98.4% confidence level. We conclude that the twodata sets are different, i.e. late-type galaxies have a broaderellipticity distribution and contain more elongated features in theinner regions. We discuss the possibility that these would correspond tobars at a later evolutionary stage, i.e. secularly evolved bars.Consequent implications are raised, and we discuss relevant questionsregarding the formation and structure of bulges. Are bulges ofearly-type and late-type spirals different? Are their formationscenarios different? Can we talk about bulges in the same way fordifferent types of galaxies?
| Beyond the Bulge: A Fundamental Relation between Supermassive Black Holes and Dark Matter Halos
The possibility that the masses MBH of supermassive blackholes (SBHs) correlate with the total gravitational mass of their hostgalaxy, or the mass MDM of the dark matter halo in which theypresumably formed, is investigated using a sample of 16 spiral and 20elliptical galaxies. The bulge velocity dispersion σc,typically defined within an aperture of size R<~0.5 kpc, is found tocorrelate tightly with the galaxy's circular velocity vc, thelatter measured at distances from the Galactic center at which therotation curve is flat, R~20-80 kpc. By using the well-knownMBH-σc relation for SBHs and a prescriptionto relate vc to the mass of the dark matter haloMDM in a standard ΛCDM cosmology, the correlationbetween σc and vc is equivalent to onebetween MBH and MDM. Such a correlation is foundto be nonlinear, with the ratio MBH/MDM decreasingfrom 2×10-4 for MDM~1014Msolar to 10-5 for MDM~1012Msolar. Preliminary evidence suggests that halos of masssmaller than ~5×1011 Msolar are increasinglyless efficient at forming SBHs-perhaps even unable to form them.
| Bar Galaxies and Their Environments
The prints of the Palomar Sky Survey, luminosity classifications, andradial velocities were used to assign all northern Shapley-Ames galaxiesto either (1) field, (2) group, or (3) cluster environments. Thisinformation for 930 galaxies shows no evidence for a dependence of barfrequency on galaxy environment. This suggests that the formation of abar in a disk galaxy is mainly determined by the properties of theparent galaxy, rather than by the characteristics of its environment.
| Local velocity field from sosie galaxies. I. The Peebles' model
Pratton et al. (1997) showed that the velocity field around clusterscould generate an apparent distortion that appears as tangentialstructures or radial filaments. In the present paper we determine theparameters of the Peebles' model (1976) describing infall of galaxiesonto clusters with the aim of testing quantitatively the amplitude ofthis distortion. The distances are determined from the concept of sosiegalaxies (Paturel 1984) using 21 calibrators for which the distanceswere recently calculated from two independent Cepheid calibrations. Weuse both B and I-band magnitudes. The Spaenhauer diagram method is usedto correct for the Malmquist bias. We give the equations for theconstruction of this diagram. We analyze the apparent Hubble constant indifferent regions around Virgo and obtain simultaneously the Local Groupinfall and the unperturbed Hubble constant. We found:[VLG-infall = 208 ± 9 km s-1] [\log H =1.82 ± 0.04 (H ≈ 66 ± 6 km s-1Mpc-1).] The front side and backside infalls can be seenaround Virgo and Fornax. In the direction of Virgo the comparison ismade with the Peebles' model. We obtain: [vinfall} =CVirgo/r0.9 ± 0.2] withCVirgo=2800 for Virgo and CFornax=1350 for Fornax,with the adopted units (km s-1 and Mpc). We obtain thefollowing mean distance moduli: [μVirgo=31.3 ± 0.2(r=18 Mpc )] [μFornax=31.7 ± 0.3 (r=22 Mpc). ] Allthese quantities form an accurate and coherent system. Full Table 2 isonly available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/57
| The Multitude of Unresolved Continuum Sources at 1.6 Microns in Hubble Space Telescope Images of Seyfert Galaxies
We examine 112 Seyfert galaxies observed by the Hubble Space Telescopeat 1.6 μm. We find that ~50% of the Seyfert 2.0 galaxies which arepart of the Revised Shapely-Ames (RSA) Catalog or the CfA redshiftsample contain unresolved continuum sources at 1.6 μm. All but acouple of the Seyfert 1.0-1.9 galaxies display unresolved continuumsources. The unresolved sources have fluxes of order 1 mJy,near-infrared luminosities of order 1041 ergs s-1,and absolute magnitudes MH~-16. Comparison non-Seyfertgalaxies from the RSA Catalog display significantly fewer (~20%),somewhat lower luminosity nuclear sources, which could be due to compactstar clusters. We find that the luminosities of the unresolved Seyfert1.0-1.9 sources at 1.6 μm are correlated with [O III] λ5007and hard X-ray luminosities, implying that these sources are nonstellar.Assuming a spectral energy distribution similar to that of a Seyfert 2galaxy, we estimate that a few percent of local spiral galaxies containblack holes emitting as Seyferts at a moderate fraction,~10-1-10-4, of their Eddington luminosities. Wefind no strong correlation between 1.6 μm fluxes and hard X-ray or [OIII] λ5007 fluxes for the pure Seyfert 2.0 galaxies. Thesegalaxies also tend to have lower 1.6 μm luminosities compared to theSeyfert 1.0-1.9 galaxies of similar [O III] luminosity. Either largeextinctions (AV~20-40) are present toward theircontinuum-emitting regions or some fraction of the unresolved sources at1.6 μm are compact star clusters. With increasing Seyfert type thefraction of unresolved sources detected at 1.6 μm and the ratio of1.6 μm to [O III] fluxes tend to decrease. These trends areconsistent with the unification model for Seyfert 1 and 2 galaxies.
| Homogenization of the Stellar Population along Late-Type Spiral Galaxies
We present a study of the broadband UBV color profiles for 257 Sbcbarred and nonbarred galaxies, using photoelectric aperture photometrydata from the literature. Using robust statistical methods, we haveestimated the color gradients of the galaxies, as well as the total andbulge mean colors. A comparative photometric study using CCD images wasdone. In our sample, the color gradients are negative (reddish inward)in approximately 59% of the objects, are almost null in 27%, and arepositive in 14%, considering only the face-on galaxies, which representapproximately 51% of the sample. The results do not change, essentially,when we include the edge-on galaxies. As a consequence of this study wehave also found that barred galaxies are overrepresented among theobjects having null or positive gradients, indicating that bars act as amechanism of homogenization of the stellar population. This effect ismore evident in the U-B color index, although it can also be detected inthe B-V color. A correlation between the total and bulge colors wasfound that is a consequence of an underlying correlation between thecolors of bulges and disks found by other authors. Moreover, the meantotal color is the same irrespective of the gradient regime, whilebulges are bluer in galaxies with null or positive gradients, whichindicates an increase of the star formation rate in the central regionsof these objects. We have also made a quantitative evaluation of theamount of extinction in the center of these galaxies. This was doneusing the Wide Field Planetary Camera 2 (WFPC2) and the Near InfraredCamera and Multi-Object Spectrometer (NICMOS) Hubble Space Telescope(HST) archival data, as well as CCD B, V, and I images. We show thatalthough the extinction in the V-band can reach values up to 2 mag inthe central region, it is unlikely that dust plays a fundamental role inglobal color gradients. We found no correlation between color and O/Habundance gradients. This result could suggest that the color gradientsare more sensitive to the age rather than to the metallicity of thestellar population. However, the absence of this correlation may becaused by dust extinction. We discuss this result by considering apicture in which bars are a relatively fast, recurrent phenomenon. Theseresults are not compatible with a pure classical monolithic scenario forbulge and disk formation. On the contrary, they favor a scenario inwhich both these components are evolving in a correlated process inwhich stellar bars play a crucial role. Based partly on observationsmade at the Pico dos Dias Observatory (PDO/LNA-CNPq), Brazil.
| Nearby Optical Galaxies: Selection of the Sample and Identification of Groups
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
| A Dynamical Study of Galaxies in the Hickson Compact Groups
To investigate dynamical properties of spiral galaxies in the Hicksoncompact groups (HCGs), we present rotation curves of 30 galaxies in 20HCGs. We found as follows: (1) There is no significant relation betweendynamical peculiarity and morphological peculiarity in HCG spiralgalaxies. (2) There is no significant relation between the dynamicalproperties and the frequency distribution of nuclear activities in HCGspiral galaxies. (3) There are no significant correlations between thedynamical properties of HCG spiral galaxies and any group properties(i.e., size, velocity dispersion, galaxy number density, and crossingtime). (4) Asymmetric and peculiar rotation curves are more frequentlyseen in the HCG spiral galaxies than in field spiral galaxies or incluster ones. However, this tendency is more obviously seen in late-typeHCG spiral galaxies. These results suggest that the dynamical propertiesof HCG spiral galaxies do not strongly correlate with the morphology,the nuclear activity, and the group properties. Our results also suggestthat more frequent galaxy collisions occur in the HCGs than in the fieldand in the clusters.
| Galaxy collisions.
Theories of how galaxies, the fundamental constituents of large-scalestructure, form and evolve have undergone a dramatic paradigm shift inthe last few decades. Earlier views were of rapid, early collapse andformation of basic structures, followed by slow evolution of the stellarpopulations and steady buildup of the chemical elements. Currenttheories emphasize hierarchical buildup via recurrent collisions andmergers, separated by long periods of relaxation and secularrestructuring. Thus, collisions between galaxies are now seen as aprimary process in their evolution. This article begins with a briefhistory; we then tour parts of the vast array of collisional forms thathave been discovered to date. Many examples are provided to illustratehow detailed numerical models and multiwaveband observations haveallowed the general chronological sequence of collisional morphologiesto be deciphered, and how these forms are produced by the processes oftidal kinematics, hypersonic gas dynamics, collective dynamical frictionand violent relaxation. Galaxy collisions may trigger the formation of alarge fraction of all the stars ever formed, and play a key role infueling active galactic nuclei. Current understanding of the processesinvolved is reviewed. The last decade has seen exciting new discoveriesabout how collisions are orchestrated by their environment, howcollisional processes depend on environment, and how these environmentsdepend on redshift or cosmological time.
| The Mass-to-Light Ratio of Binary Galaxies
We report on the mass-to-light ratio determination based on a newlyselected binary galaxy sample, which includes a large number of pairswhose separations exceed a few hundred kpc. The probabilitydistributions of the projected separation and the velocity differencehave been calculated considering the contamination of optical pairs, andthe mass-to-light (M/L) ratio has been determined based on the maximumlikelihood method. The best estimate of the M/L in the B band for 57pairs is found to be 28-36 depending on the orbital parameters and thedistribution of optical pairs (solar unit: H_0=50 km s^-1 Mpc^-1). Thebest estimate of the M/L for 30 pure spiral pairs is found to be 12-16.These results are relatively smaller than those obtained in previousstudies but are consistent with each other within the errors. Althoughthe number of pairs with large separation is significantly increasedcompared with previous samples, the M/L does not show any tendency ofincrease but is found to be almost independent of the separation ofpairs beyond 100 kpc. The constancy of the M/L beyond 100 kpc mayindicate that the typical halo size of spiral galaxies is less than ~100kpc.
| Bulge-Disk Decomposition of 659 Spiral and Lenticular Galaxy Brightness Profiles
We present one of the largest homogeneous sets of spiral and lenticulargalaxy brightness profile decompositions completed to date. The 659galaxies in our sample have been fitted with a de Vaucouleurs law forthe bulge component and an inner-truncated exponential for the diskcomponent. Of the 659 galaxies in the sample, 620 were successfullyfitted with the chosen fitting functions. The fits are generally welldefined, with more than 90% having rms deviations from the observedprofile of less than 0.35 mag. We find no correlations of fittingquality, as measured by these rms residuals, with either morphologicaltype or inclination. Similarly, the estimated errors of the fittedcoefficients show no significant trends with type or inclination. Thesedecompositions form a useful basis for the study of the lightdistributions of spiral and lenticular galaxies. The object base issufficiently large that well-defined samples of galaxies can be selectedfrom it.
| Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| A catalogue of spatially resolved kinematics of galaxies: Bibliography
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Hubble constant from sosie galaxies and HIPPARCOS geometrical calibration
New distances, larger than previous ones, have been obtained for M 31and M 81 based on the geometrical zero-point of the CepheidPeriod-luminosity relation provided by the HIPPARCOS satellite. Bycombining them with independent determinations we define reasonableranges for the distances of these important calibrating galaxies. Onthis basis, we determine the Hubble constant from the method of sosies(look-alike) galaxies, galaxies having the same characteristics than thecalibrators. The method is quite secure because it is purelydifferential and it does not depend on any assumption (apart from thenatural one that two sosies galaxies have similar absoluteluminosities). Nevertheless, the Malmquist bias has to be taken intoaccount. The observations behave exactly as predicted from theanalytical formulation of the bias. Thus, rejecting galaxies which areaffected by the Malmquist bias we derive the Hubble constant: H_o = 60+/- 10 (external) km.s^{-1}.Mpc^{-1} If we strictly use the calibrationobtained with HIPPARCOS and if the bias found in the Period-LuminosityRelation is considered, the Hubble constant is smaller than this (~ 55km.s(-1}.Mpc({-1)) ). This gives arguments in favour of thelong-distance scale. We briefly discuss possible improvements aiming atstill reducing the uncertainty.
| More Satellites of Spiral Galaxies
We present a revised and expanded catalog of satellite galaxies of a setof isolated spiral galaxies similar in luminosity to the Milky Way. Thissample of 115 satellites, 69 of which were discovered in our multifiberredshift survey, is used to probe the results obtained from the originalsample further (Zaritsky et al.). The satellites are, by definition, atprojected separations <~500 kpc, have absolute recessional velocitydifferences with respect to the parent spiral of less than 500 km s-1,and are at least 2.2 mag fainter than their associated primary galaxy. Akey characteristic of this survey is the strict isolation of thesesystems, which simplifies any dynamical analysis. We find no evidencefor a decrease in the velocity dispersion of the satellite system as afunction of radius out to galactocentric radii of 400 kpc, whichsuggests that the halo extends well beyond 200 kpc. Furthermore, the newsample affirms our previous conclusions (Zaritsky et al.) that (1) thevelocity difference between a satellite and its primary is not stronglycorrelated with the rotation speed of the primary, (2) the system ofsatellites has a slight net rotation (34 +/- 14 km s-1) in the samesense as the primary's disk, and (3) that the halo mass of an ~L* spiralgalaxy is in excess of 2 x 1012 Mȯ.
| Optical Rotation Curves and Linewidths for Tully-Fisher Applications
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2402C&db_key=AST
| Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation
I-band luminosities, rotational velocities, and redshifts of 1092 spiralgalaxies have been measured by CCD photometry and Hα spectroscopyusing the 1 m and 2.3 m telescopes at Siding Spring Observatory,respectively. The results are tabulated. Luminosity profiles andHα rotation curves are given for the galaxies. When these resultsare combined with similar data for 1355 spiral galaxies publishedpreviously (Mathewson, Ford, & Buchhorn, hereafter Paper I), itprovides a large, uniform, and unique data set with which to measure,via the Tully-Fisher relation, the peculiar velocities of galaxies inthe local universe to a distance of 11,000 km s^-1^ (Mathewson &Ford). Taking advantage of the opportunity for publishing this data inmachine-readable form, in the CD-ROM, we have also included similar datafor the 1355 galaxies in Paper I.
| Bias Properties of Extragalactic Distance Indicators. VI. Luminosity Functions of M31 and M101 Look-alikes Listed in the RSA2: H0 Therefrom
Galaxies whose morphologies are similar to M 101 (Sc I) and M3 1 (Sb I-II) are listed in two tables. The selection is made by inspecting directimages of Shapley-Ames galaxies in the recent Carnegie Atlas ofGalaxies. Absolute magnitudes, calculated from redshifts, give meanvalues of
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
| A comparative study of morphological classifications of APM galaxies
We investigate the consistency of visual morphological classificationsof galaxies by comparing classifications for 831 galaxies from sixindependent observers. The galaxies were classified on laser print copyimages or on computer screen using scans made with the Automated PlateMeasuring (APM) machine. Classifications are compared using the RevisedHubble numerical type index T. We find that individual observers agreewith one another with rms combined dispersions of between 1.3 and 2.3type units, typically about 1.8 units. The dispersions tend to decreaseslightly with increasing angular diameter and, in some cases, withincreasing axial ratio (b/a). The agreement between independentobservers is reasonably good but the scatter is non-negligible. In spiteof the scatter, the Revised Hubble T system can be used to train anautomated galaxy classifier, e.g. an artificial neural network, tohandle the large number of galaxy images that are being compiled in theAPM and other surveys.
| Nuclear bars and blue nuclei within barred spiral galaxies
Multicolour near-IR photometry for a sample of 32 large barred spiralgalaxies is presented. By applying ellipse-fitting techniques, weidentify significant isophote twists with respect to the primary baraxis in the nuclear regions of ~70 per cent of the sample. These twistsare identified in galaxies as late as SBbc, and are clearlydistinguishable from spiral-arm structure. At most, seven of thegalaxies with isophote twists are inferred to possess secondary(nuclear) bars, the axial ratios of which appear to correlate withmorphological type. The remainder may result from triaxial bulges, orfrom oblate bulges misaligned with the primary bar. The near-IR colourdistributions in these data show evidence for (red) circumnuclearstar-forming rings in four galaxies. The majority of the sample (19)also possess striking blue nuclear regions, bluer than typical oldstellar populations by ~0.3 mag in (J-H) and ~0.23 mag in (H-K). Suchblue colours do not appear to correlate with the presence of nuclearrings or pseudo-rings, nor with the activity of the host galaxy (asdetermined from emission-line spectroscopic characteristics). Severalmechanisms to explain this blue colour are considered.
| A Catalog of Stellar Velocity Dispersions. II. 1994 Update
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
| Rotation Curves of 967 Spiral Galaxies
We present the rotation curves of 967 southern spiral galaxies, obtainedby deprojecting and folding the raw Hα data originally publishedby Mathewson, Ford, & Buchhorn (1992). For 900 objects, we alsopresent, in figures and tables, the rotation curves smoothed on scalescorresponding to 5%-20% of the optical size; of these, 80 meet objectiveexcellence criteria and are suitable for individual detailed massmodeling, while 820, individually less compelling mainly because of themoderate statistics and/or limited extension, are suitable forstatistical studies. The remaining 67 curves suffer from severeasymmetries, small statistics, and large internal scatter that maylargely limit their use in galaxy structure studies. The deprojectedfolded curves, the smoothed curves, and various related quantities areavailable via anonymous ftp at galileo.sissa.it in the directory/users/ftp/pub/psrot.
| Dark Matter Particles and the Flat Rotation Curves of Spiral Galaxies
Not Available
| A Preliminary Classification Scheme for the Central Regions of Late-Type Galaxies
The large-scale prints in The Carnegie Atlas of Galaxies have been usedto formulate a classification scheme for the central regions oflate-type galaxies. Systems that exhibit small bright central bulges ordisks (type CB) are found to be of earlier Hubble type and of higherluminosity than galaxies that do not contain nuclei (type NN). Galaxiescontaining nuclear bars, or exhibiting central regions that are resolvedinto individual stars and knots, and galaxies with semistellar nuclei,are seen to have characteristics that are intermediate between those oftypes CB and NN. The presence or absence of a nucleus appears to be auseful criterion for distinguishing between spiral galaxies andmagellanic irregulars.
| Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.
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