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Multicomponent decompositions for a sample of S0 galaxies
We have estimated the bulge-to-total (B/T) light ratios in theKs band for a sample of 24 S0, S0/a and Sa galaxies byapplying a two-dimensional multicomponent decomposition method. For thedisc an exponential function is used, the bulges are fitted by aSérsic R1/n function and the bars and ovals aredescribed either by a Sérsic or a Ferrers function. In order toavoid non-physical solutions, preliminary characterization of thestructural components is made by inspecting the radial profiles of theorientation parameters and the low azimuthal wavenumber Fourieramplitudes and phases. In order to identify also the inner structures,unsharp masks were created: previously undetected inner spiral arms werefound in NGC 1415 and marginally in NGC 3941. Most importantly, we foundthat S0s have a mean K ratio of 0.24 +/- 0.11,which is significantly smaller than the mean R=0.6 generally reported in the literature. Also, the surface brightnessprofiles of the bulges in S0s were found to be more exponential-likethan generally assumed, the mean shape parameter of the bulge being= 2.1 +/- 0.7. We did not find examples of barred S0s lackingthe disc component, but we found some galaxies (NGC 718, 1452 and 4608)having a non-exponential disc in the bar region. To our knowledge, ourstudy is the first attempt to apply a multicomponent decompositionmethod for a moderately sized sample of early-type disc galaxies.
| Radio Continuum and Far-infrared Emission from the Galaxies in the Eridanus Group
The Eridanus galaxies follow the well-known radio-FIR correlation. Themajority (70%) of these galaxies have their star formation rates belowthat of the Milky Way. The galaxies that have a significant excess ofradio emission are identified as low luminosity AGNs based on theirradio morphologies obtained from the GMRT observations. There are nopowerful AGNs (L20 cm>1023WHz-1) in the group. The twomost far-infrared and radio luminous galaxies in the group have opticaland HI morphologies suggestive of recent tidal interactions. TheEridanus group also has two far-infrared luminous but radio-deficientgalaxies. It is believed that these galaxies are observed within a fewMyr of the onset of an intense star formation episode after beingquiescent for at least a 100 Myr. The upper end of the radio luminositydistribution of the Eridanus galaxies (L20 cm1022WHz-1) isconsistent with that of the field galaxies, other groups, and late-typegalaxies in nearby clusters.
| GMRT HI Observations of the Eridanus Group of Galaxies I.
The GMRT HI 21cm-line observations of galaxies in the Eridanus group arepresented. The Eridanus group, at a distance of ~23 Mpc, is a loosegroup of ~200 galaxies. The group extends to more than 10 Mpc inprojection. The velocity dispersion of the galaxies in the group is ~240km s-1. The galaxies are clustered into different sub-groups. Theoverall population mix of the group is 30% (E + S0) and 70% (Sp + Irr).The observations of 57 Eridanus galaxies were carried out with the GMRTfor ~ 200 h. HI emission was detected from 31 galaxies. The channel rmsof ~1 mJy beam-1 was achieved for most of the image-cubes made with 4 hof data. The corresponding HI column density sensitivity (3σ) is~1 × 1020 cm-2 for a velocity-width of ~ 13.4 km s-1.The 3σ detection lss surface densities, HI disk parameters and HIrotation curves are presented. The velocity fields are analysedseparately for the approaching and the receding sides of the galaxies.These data will be used to study the HI and the radio continuumproperties, the Tully-Fisher relations, the dark matter halos, and thekinematical and HI lopsidedness in galaxies.
| On the Relevance of the Tremaine-Weinberg Method Applied to an Hα Velocity Field: Pattern Speed Determination in M100 (NGC 4321)
The relevance of the Tremaine-Weinberg (TW) method is tested formeasuring bar, spiral, and inner structure pattern speeds using agaseous velocity field. The TW method is applied to various simulatedbarred galaxies in order to demonstrate its validity in seven differentconfigurations, including star formation and/or dark matter halo. Thereliability of the different physical processes involved and of thevarious observational parameters is also tested. The simulations showthat the TW method could be applied to gaseous velocity fields to get agood estimate of the bar pattern speed, under the condition that regionsof shocks are avoided and measurements are confined to regions where thegaseous bar is well formed. We successfully apply the TW method to theHα velocity field of the Virgo Cluster galaxy M100 (NGC 4321) andderive pattern speeds of 55+/-5 km s-1 kpc-1 forthe nuclear structure, 30+/-2 km s-1 kpc-1 for thebar, and 20+/-1 km s-1 kpc-1 for the spiralpattern, in full agreement with published determinations using the samemethod or alternative ones.
| The Vertical Stellar Kinematics in Face-On Barred Galaxies: Estimating the Ages of Bars
In order to perform a detailed study of the stellar kinematics in thevertical axis of bars, we obtained high signal-to-noise spectra alongthe major and minor axes of the bars in a sample of 14 face-on galaxiesand used them to determine the line-of-sight stellar velocitydistribution, parameterized as a Gauss-Hermite series. With these data,we developed a diagnostic tool that allows one to distinguish betweenrecently formed and evolved bars, as well as to estimate their ages,assuming that bars form in vertically thin disks that are recognizableby low values for the vertical velocity dispersion σz.Through N-body realizations of bar unstable disk galaxies we were alsoable to check the timescales involved in the processes that give bars animportant vertical structure. We show that σz inevolved bars is roughly 100 km s-1, which translates to aheight scale of about 1.4 kpc, giving support to scenarios in whichbulges form through disk material. Furthermore, the bars in ournumerical simulations have values for σz generallysmaller than 50 km s-1, even after evolving for 2 Gyr,suggesting that a slow process is responsible for making bars asvertically thick as we observe. We verify theoretically that theSpitzer-Schwarzschild mechanism is quantitatively able to explain theseobservations if we assume that giant molecular clouds are twice asconcentrated along the bar as in the rest of the disk.
| Photometric properties and origin of bulges in SB0 galaxies
We have derived the photometric parameters for the structural componentsof a sample of fourteen SB0 galaxies by applying a parametricphotometric decomposition to their observed I-band surface brightnessdistribution. We find that SB0 bulges are similar to bulges of theearly-type unbarred spirals, i.e. they have nearly exponential surfacebrightness profiles (< n>=1.48±0.16) and their effectiveradii are strongly coupled to the scale lengths of their surroundingdiscs (< r_e/h>=0.20±0.01). The photometric analysis alonedoes not allow us to differentiate SB0 bulges from unbarred S0 ones.However, three sample bulges have disc properties typical ofpseudobulges. The bulges of NGC 1308 and NGC 4340 rotate faster thanbulges of unbarred galaxies and models of isotropic oblate spheroidswith equal ellipticity. The bulge of IC 874 has a velocity dispersionlower than expected from the Faber-Jackson correlation and thefundamental plane of the elliptical galaxies and S0 bulges. Theremaining sample bulges are classical bulges, and are kinematicallysimilar to lower-luminosity ellipticals. In particular, they follow theFaber-Jackson correlation, lie on the fundamental plane and those forwhich stellar kinematics are available rotate as fast as the bulges ofunbarred galaxies.
| Dynamical modelling of the remarkable four-armed barred spiral galaxy ESO 566-24
ESO 566-24 is an extraordinary barred galaxy that has four regularlyspaced spiral arms in blue light images. This type of spiral structure,which is rare among the spiral population, is also clearly seen innear-infrared (NIR) images, and thus is present in the old stellarpopulation. We have constructed dynamical models of ESO 566-24. Thegravitational potential is determined using NIR photometry, and the gasdynamics is modelled as inelastically colliding particles. The resultingmorphology and kinematics with different assumed pattern speeds, discvertical thicknesses and dark halo contributions are compared withobservations. Our models reproduce the main morphological features ofthis galaxy: the four-armed spiral, and the inner and nuclear rings. Thepattern speed of the bar is such that the corotation resonance is welloutside the bar radius, rCR/rb= 1.6 +/- 0.3. Thefour-armed spiral resides in the region between inner and outer 4/1resonances. In addition, the main kinematical features, includingbar-induced deviations from circular rotation, are explained by ourmodels. The best fit is obtained when the dark halo contribution is justenough to make the modelled rotation curve match the observed one. Thus,luminous matter dominates the rotation curve within the disc region.
| Fast bars in SB0 galaxies
We measured the bar pattern speed in a sample of 7 SB0 galaxies usingthe Tremaine-Weinberg method. This represents the largest sample ofgalaxies for which the bar pattern speed has been measured this way. Allthe observed bars are as rapidly rotating as they can be. We comparedthis result with recent high-resolution N-body simulations of bars incosmologically-motivated dark matter halos, and conclude that these barsare not located inside centrally concentrated halos.
| Detailed comparison of the structures and kinematics of simulated and observed barred galaxies
We examine the observable properties of simulated barred galaxies,including radial mass profiles, edge-on structure and kinematics, barlengths and pattern speed evolution for detailed comparison to realsystems. We have run several simulations in which bars are createdthrough inherent instabilities in self-consistent simulations of arealistic disc+halo galaxy model with a disc-dominated, flat rotationcurve. These simulations were run at high (N= 20 million particles) andlow (N= 500000 particles) resolution to test numerical convergence. Wedetermine the pattern speeds in simulations directly from the phaseangle of the bar versus time and the Tremaine-Weinberg method.Fundamental dynamics do not change between the high and low resolution,suggesting that convergence has been reached in this case. We find thatthe higher resolution is needed to simulate structural and kinematicproperties accurately. The edge-on view of the higher-resolution systemshows the bending instability and formation of a peanut-shaped bulgeclearly. We determined bar lengths by different means to determine thatthe simulated bar is fast, with a corotation to bar length ratio ofunder 1.5. Simulated bars in these models form with pattern speedsslower than those observed and slow-down during their evolution.Dynamical friction between the bar and dark halo is responsible for thisdeceleration, as revealed by the transfer of angular momentum betweenthe disc and the halo. However, even though the pattern speed is reducedat later times, the instantaneous scalelength of the disc has grownsufficiently for the bar motion to agree with many observations. Byusing a different model and simulation technique than other authors, weare able to compare the robustness of these methods. An animation of theface-on and edge-on views of the 20-million-particle simulation isavailable at http://www.astro.utoronto.ca/~oneill.
| Secular bar formation in galaxies with a significant amount of dark matter
Using high-resolution N-body simulations of stellar discs embedded incosmologically motivated dark matter haloes, we study the evolution ofbars and the transfer of angular momentum between haloes and bars. Wefind that dynamical friction results in some transfer of angularmomentum to the halo, but the effect is much smaller than previouslyfound in low-resolution simulations and is incompatible with earlyanalytical estimates. After 5 Gyr of evolution the stellar componentloses only 5-7 per cent of its initial angular momentum.Mass and force resolutions are crucial for the modelling of bardynamics. In low-resolution (300-500 pc) simulations we find that thebar slows down and angular momentum is lost relatively fast. Insimulations with millions of particles reaching a resolution of 20-40pc, the pattern speed may not change over billions of years. Ourhigh-resolution models produce bars that are fast rotators, where theratio of the corotation radius to the bar semi-major axis lies in therange , marginally compatible with observational results. In contrast tomany previous simulations, we find that bars are relatively short. As inmany observed cases, the bar semi-major axis is close to the exponentiallength of the disc.The transfer of angular momentum between inner and outer parts of thedisc plays a very important role in the secular evolution of the discand the bar. The bar formation increases the exponential length of thedisc by a factor of 1.2-1.5. The transfer substantially increases thestellar mass in the centre of the galaxy and decreases the dark matterto baryon ratio. As the result, the central 2-kpc region is alwaysstrongly dominated by the baryonic component. At intermediate (3-10 kpc)scales the disc is sub-dominant. These models demonstrate that theefficiency of angular momentum transfer to the dark matter has beengreatly overestimated. More realistic models produce bar structure instriking agreement with observational results.
| On position angle errors in the Tremaine-Weinberg method
I show that Tremaine-Weinberg (TW) measurements of bar pattern speedsare sensitive to errors in the position angle of the disc,PAdisc. I use an N-body experiment to measure these errors;for typical random PAdisc errors, the resulting scatter inthe measured values of the dimensionless bar speed parameter (defined asthe ratio of the corotation radius to the bar semi-major axis) is of theorder of the scatter in the observed values.I also consider how the systematic PAdisc errors produced bydisc ellipticities affect TW measurements. The scatter produced by theseerrors may be significant, depending on the ellipticity distribution.Conversely, by using the sample of TW observations, I find that an upperlimit of the typical disc (density) ellipticity is 0.07 at the 90 percent confidence level, which is in good agreement with previousmeasurements.Taken together, the random and systematic scatter suggest that theintrinsic distribution of of gas-poor early-type barred galaxies may beas narrow as that of the gas-rich later types.
| Measurement of fast bars in a sample of early-type barred galaxies
We present surface photometry and stellar kinematics of a sample of fiveSB0 galaxies: ESO 139-G009, IC 874, NGC 1308, NGC 1440 and NGC 3412. Wemeasured their bar pattern speed using the Tremaine-Weinberg method, andderived the ratio, , of the corotation radius to the length of the barsemimajor axis. For all the galaxies, is consistent with being in therange from 1.0 to 1.4, i.e. that they host fast bars. This representsthe largest sample of galaxies for which has been measured in this way.Taking into account the measured distribution of and our measurementuncertainties, we argue that this is probably the true distribution of .If this is the case, then the Tremaine-Weinberg method finds adistribution of which is in agreement with that obtained byhydrodynamical simulations. We compare this result with recenthigh-resolution N-body simulations of bars in cosmologically motivateddark matter haloes, and we conclude that these bars are not locatedinside centrally concentrated dark matter haloes.
| Fast bars in early-type barred galaxies
We measured the bar pattern speed of a sample of 6 SB0 galaxies usingthe Tremaine-Weinberg method. We derived the ratio, {cal R}, of thecorotation radius to the length of the bar semi-major axis. For all thegalaxies, {cal R} is consistent with being in the range from 1.0 and1.4, i.e. that they host fast bars. This represents the largest sampleof galaxies for which {cal R} has been measured this way. We comparedthis result with recent high-resolution N-body simulations of bars incosmologically-motivated dark matter halos, and conclude that these barsare not located inside centrally concentrated dark matter halos.
| Redshift-Distance Survey of Early-Type Galaxies: Spectroscopic Data
We present central velocity dispersions and Mg2 line indicesfor an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984had no previous measures. This sample contains the largest set ofhomogeneous spectroscopic data for a uniform sample of ellipticalgalaxies in the nearby universe. These galaxies were observed as part ofthe ENEAR project, designed to study the peculiar motions and internalproperties of the local early-type galaxies. Using 523 repeatedobservations of 317 galaxies obtained during different runs, the dataare brought to a common zero point. These multiple observations, takenduring the many runs and different instrumental setups employed for thisproject, are used to derive statistical corrections to the data and arefound to be relatively small, typically <~5% of the velocitydispersion and 0.01 mag in the Mg2 line strength. Typicalerrors are about 8% in velocity dispersion and 0.01 mag inMg2, in good agreement with values published elsewhere.
| A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| 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.
| 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.
| 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.
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| 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.
| 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 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.
| S0's and the lower limit of star-formation rates in disk galaxies
As an extension of our study of star formation and H II regions in Sagalaxies, we have observed eight disk galaxies classified S0-S0/Sa. Wehave detected discrete H II regions in three of these, all classifiedS0/Sa because their faint star-forming regions are visible on broadbandimages. Each of these galaxies has about 15 H II regions, with a totalluminosity in H-alpha between L = 1038.3 and1037.7 ergs/s. The star-formation rate in these galaxiesimplied by the H-alpha luminosity is less than 0.004 solar mass/yr, ascomparted to greater than 0.1 solar mass/yr in Sa galaxies. We concludethat normal star formation in disk galaxies can occur in exceedinglysmall amounts.
| Mean morphological types of bright galaxies
The revised Hubble classifications provided in the Third ReferenceCatalogue of Bright Galaxies (RC3) are based on nine lists andcatalogues, both published and unpublished, from five observers. Thispaper describes the procedures that were used to combine theseclassifications into mean classifications including the family, variety,and stage. The best classifications in RC3 are based on large-scalephotographic images taken with 1.5-5 m class reflectors. However, mostof the types in RC3 are based on the small-scale prints, plates, andfilms of the first Palomar Sky Survey and the UK Schmidt IIIa-J SouthernSky Survey. The overlap between the different observers, samples alloweddetermination of the reliability of sky survey types and the effects ofdiameter and inclination on the accuracy of these types. We find thatfor a typical galaxy having isophotal diameter D25approximately = 2 min and inclined by approximately 50 degs, types Tfrom the sky surveys have a mean error (averaged over all of theobservers) of sigma(T) = 0.7 step on the numerical scale of the revisedHubble system. With the new database of classifications, we rederive theclassical relations between Hubble type and integrated colors, surfacebrightnesses, and hydrogen index (hydrogen flux to blue light ratio) fora large sample of galaxies. We also present a table of galaxies which weconsider to be representative examples of each type.
| The dependence of the cool matter content on galaxy morphology in galaxies of types E/S0, S0, and SA
Using the material assembled in earlier papers, we examine the manner inwhich the interstellar matter content varies along the Hubble sequencefrom S0 galaxies to Sa galaxies selected from the RSA2 compilation. Forthis we make use of a new and more detailed classification which isdescribed here as applied to these early disk/spiral galaxies. Theprominence of the disk in S0's and the visibility of features (H IIregions) in the Sa's serve as the basis for the subtypes. Three S0categories: subtle, intermediate, and pronounced, and four Sadescriptors: very early, early, intermediate, and late are assigned tothe galaxies. It is found that the total amount of hydrogen (H I + H2)is a function of subtype, being low in the S0's and rising smoothly fromthe early Sa's to the later Sa's. The average surface density ofhydrogen exceeds 3 solar masses/pc-squared only in the latest subtypesof the Sa's. We conclude that the prominence of the disk of a galaxyclosely follows the amount of cool gas which the disk contains.
| General study of group membership. II - Determination of nearby groups
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
| Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
| Southern Sky Redshift Survey - The catalog
The catalog of radial velocities for galaxies which comprise thediameter-limited sample of the Southern Sky Redshift Survey ispresented. It consolidates the data of observations carried out at theLas Campanas Observatory, Observatorio Nacional, and South AfricanAstronomical Observatory. The criteria used for the sample selection aredescribed, as well as the observational procedures and the techniqueutilized to obtain the final radial velocities. The intercomparisonbetween radial velocity measurements from different telescopes indicatesthat the final data base is fairly homogeneous with a typical error ofabout 40 km/s. The sample is at present 90 percent complete, and themissing galaxies are predominantly objects with very low surfacebrightness for which it is very difficult to obtain optical redshifts.
| Interstellar matter in early-type galaxies. I - The catalog
A catalog is given of the currently available measurements ofinterstellar matter in the 467 early-type galaxies listed in the secondedition of the Revised Shapley-Ames Catalog of Bright Galaxies. Themorphological type range is E, SO, and Sa. The ISM tracers are emissionin the following bands: IRAS 100 micron, X-ray, radio, neutral hydrogen,and carbon monoxide. Nearly two-thirds of the Es and SOs have beendetected in one or more of these tracers. Additional observed quantitiesthat are tabulated include: magnitude, colors, radial velocity, centralvelocity dispersion, maximum of the rotation curve, angular size, 60micron flux, and supernovae. Qualitative statements as to the presenceof dust or emission lines, when available in the literature, are given.Quantities derivative from the observed values are also listed andinclude masses of H I, CO, X-ray gas, and dust as well as an estimate ofthe total mass and mass-to-luminosity ratio of the individual galaxies.
| H I content and FIR emission of S0 galaxies
A sample of 252 S0 galaxies is used to study the relationship between HI content and far-IR emission. Logarithms of the H I content versus thefar-IR emission are employed statistically to develop a best-fit linearregression line which is compared to a slope of approximately unity. Theslopes are different for S0 and SB0 galaxies versus S0/a and SB0/agalaxies. The distribution of the 60-100 micron flux ratio is notsignificantly affected by the presence or absence of bars nor by thedifferences between the S0 and S0/a systems. The flux ratio is higherthan the critical value of Helou in 34 percent of the cases, and thevalue holds when nuclear emission is taken into account. In cases wherethe critical value is exceeded, most far-IR emissions are expected to bedue to star formation. S0 galaxies are generally found to have a normalISM, except where the systems have accreted their H I gas. Systems withdisproportionate FIR emission can be considered galaxies that areexperiencing enhanced star formation or that have had their H I gasswept away.
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