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The SAURON project - VII. Integral-field absorption and emission-line kinematics of 24 spiral galaxy bulges
We present observations of the stellar and gas kinematics for arepresentative sample of 24 Sa galaxies obtained with our custom-builtintegral-field spectrograph SAURON operating on the William HerschelTelescope. The data have been homogeneously reduced and analysed bymeans of a dedicated pipeline. All resulting data cubes were spatiallybinned to a minimum mean signal-to-noise ratio of 60 per spatial andspectral resolution element. Our maps typically cover thebulge-dominated region. We find a significant fraction of kinematicallydecoupled components (12/24), many of them displaying central velocitydispersion minima. They are mostly aligned and co-rotating with the mainbody of the galaxies, and are usually associated with dust discs andrings detected in unsharp-masked images. Almost all the galaxies in thesample (22/24) contain significant amounts of ionized gas which, ingeneral, is accompanied by the presence of dust. The kinematics of theionized gas are consistent with circular rotation in a disc co-rotatingwith respect to the stars. The distribution of mean misalignmentsbetween the stellar and gaseous angular momenta in the sample suggeststhat the gas has an internal origin. The [OIII]/Hβ ratio is usuallyvery low, indicative of current star formation, and shows variousmorphologies (ring-like structures, alignments with dust lanes oramorphous shapes). The star formation rates (SFRs) in the sample arecomparable with that of normal disc galaxies. Low gas velocitydispersion values appear to be linked to regions of intense starformation activity. We interpret this result as stars being formed fromdynamically cold gas in those regions. In the case of NGC5953, the datasuggest that we are witnessing the formation of a kinematicallydecoupled component from cold gas being acquired during the ongoinginteraction with NGC5954.
| Circumnuclear Structure and Black Hole Fueling: Hubble Space Telescope NICMOS Imaging of 250 Active and Normal Galaxies
Why are the nuclei of some galaxies more active than others? If mostgalaxies harbor a central massive black hole, the main difference isprobably in how well it is fueled by its surroundings. We investigatethe hypothesis that such a difference can be seen in the detailedcircumnuclear morphologies of galaxies using several quantitativelydefined features, including bars, isophotal twists, boxy and diskyisophotes, and strong nonaxisymmetric features in unsharp-masked images.These diagnostics are applied to 250 high-resolution images of galaxycenters obtained in the near-infrared with NICMOS on the Hubble SpaceTelescope. To guard against the influence of possible biases andselection effects, we have carefully matched samples of Seyfert 1,Seyfert 2, LINER, starburst, and normal galaxies in their basicproperties, taking particular care to ensure that each was observed witha similar average scale (10-15 pc pixel-1). Severalmorphological differences among our five different spectroscopicclassifications emerge from the analysis. The H II/starburst galaxiesshow the strongest deviations from smooth elliptical isophotes, whilethe normal galaxies and LINERs have the least disturbed morphology. TheSeyfert 2s have significantly more twisted isophotes than any othercategory, and the early-type Seyfert 2s are significantly more disturbedthan the early-type Seyfert 1s. The morphological differences betweenSeyfert 1s and Seyfert 2s suggest that more is at work than simply theviewing angle of the central engine. They may correspond to differentevolutionary stages.
| Infrared Observations of Galaxies in the Local Universe. II. 391 Calibrated Images with Photometric and Structural Measurements
This paper presents empirical results from a deep imaging survey ofgalaxies in the local universe at the J and Ks wavelengths.Three hundred ninety-one images have been obtained and calibrated usingthe same camera and filter set with the Steward Observatory 1.6 m KuiperTelescope on Mount Bigelow and the 2.3 m Bok Telescope on Kitt Peak. Thelimiting magnitude is typically 22 mag arcsec-1 at J and 21mag arcsec-1 at Ks. The central surfacebrightness, apparent magnitudes, sizes, scale lengths, and inclinationsare tabulated from measurements made using these data. The purpose ofthis paper is to provide basic near-infrared data on a variety of galaxytypes.
| The Near-Infrared Ca II Triplet-σ Relation for Bulges of Spiral Galaxies
We present measurements of the near-infrared Ca II triplet (CaT, CaT*),Paschen (PaT), and magnesium (Mg I) indices for a well-studied sample of19 bulges of early to intermediate spiral galaxies. We find that boththe CaT* and CaT indices decrease with central velocity dispersionσ with small scatter. This dependence is similar to that recentlyfound by Cenarro for elliptical galaxies, implying a uniformCaT*-σ relation that applies to galaxies from ellipticals tointermediate-type spirals. The decrease of CaT and CaT* with σcontrasts with the well-known increase of another α-element index,Mg2, with σ. We discuss the role of Ca underabundance([Ca/Fe]<0) and initial mass function variations in the onset of theobserved relations.
| Minor axis kinematics of 19 S0-Sbc bulges
We present minor axis kinematic profiles for a well-studied sample of 19early- to intermediate-type disk galaxies. We introduce, for the firsttime, the use of single-burst stellar population (SSP) models to obtainstellar velocities, velocity dispersions and higher order Gauss-Hermitemoments (h3, h4) from galaxy spectra in thenear-infrared Ca II triplet region. SSP models, which employs thesynthetic spectra of \citet{vazdekis03}, provide a means to address thetemplate-mismatch problem, and are shown to provide as good or betterfits as traditional stellar templates. We anticipate the technique to beof particular use for high-redshift galaxy kinematics. We give themeasurement of a recently defined CaT* index\citep{cenarro01}, and describe the global properties of the bulgekinematics as derived from the kinematic profiles. We detectsmall-amplitude minor-axis rotation, generally due to inner isophotaltwists as a result of slightly triaxial bulges or misaligned innerdisks; such inner features do not show peculiar colors or distinctCaT* index values. Velocity dispersion profiles, which extendwell into the disk region, show a wide range of slopes. Flattened bulgestend to have shallower velocity dispersion profiles. The inferredsimilarity of bulge and disk radial velocity dispersions supports theinterpretation of these bulges as thickened disks.Appendix B is only available in electronic form athttp://www.edpsciences.org
| Bulges on the Fundamental Plane of early-type galaxies
In an ongoing effort to study the formation and evolution of galacticbulges, we have investigated the position of 19 bulges of type S0-Sbc onthe Fundamental Plane (FP). We find that bulges, in both B and K band,lie close to but slightly below the FP defined by ellipticals and S0s,i.e. are slightly brighter. There are hints that bulges of latermorphological type are situated below the other bulges in our sample.The FP results are consistent with the picture, obtained from our recentanalysis of HST colours, that bulges are old, except for the Sbcgalaxies. The fact that bulges lie so close to the FP of ellipticals andS0s implies that their formation epoch must have been similar to, atmost about 2.5 Gyr earlier than, cluster Es and S0s, and that thesurrounding disc does not significantly affect their structure.
| The SAURON project - II. Sample and early results
Early results are reported from the SAURON survey of the kinematics andstellar populations of a representative sample of nearby E, S0 and Sagalaxies. The survey is aimed at determining the intrinsic shape of thegalaxies, their orbital structure, the mass-to-light ratio as a functionof radius, the age and metallicity of the stellar populations, and thefrequency of kinematically decoupled cores and nuclear black holes. Theconstruction of the representative sample is described, and itsproperties are illustrated. A comparison with long-slit spectroscopicdata establishes that the SAURON measurements are comparable to, orbetter than, the highest-quality determinations. Comparisons arepresented for NGC 3384 and 4365, where stellar velocities and velocitydispersions are determined to a precision of 6kms-1, and theh3 and h4 parameters of the line-of-sight velocitydistribution to a precision of better than 0.02. Extraction of accurategas emission-line intensities, velocities and linewidths from the datacubes is illustrated for NGC 5813. Comparisons with published linestrengths for NGC 3384 and 5813 reveal uncertainties of <~0.1Åon the measurements of the Hβ, Mg b and Fe5270 indices.Integral-field mapping uniquely connects measurements of the kinematicsand stellar populations to the galaxy morphology. The maps presentedhere illustrate the rich stellar kinematics, gaseous kinematics, andline-strength distributions of early-type galaxies. The results includethe discovery of a thin, edge-on, disc in NGC 3623, confirm theaxisymmetric shape of the central region of M32, illustrate the LINERnucleus and surrounding counter-rotating star-forming ring in NGC 7742,and suggest a uniform stellar population in the decoupled core galaxyNGC 5813.
| A K-band central disc surface brightness correlation with scalelength for early-type disc galaxies, and the inclination correction
The K-band light profiles from two statistically complete,diameter-limited samples of disc galaxies have been simultaneouslymodelled with a seeing-convolved Sérsic r1/n bulge anda seeing-convolved exponential disc. This has enabled an accurateseparation of the bulge and disc light, and hence an estimate of thecentral disc surface brightness μ0,K and the discscalelength h. There exists a bright envelope of galaxy discs in theμ0,K-logh diagram; for the early-type (<=Sbc-Sc) discgalaxies μ0,K is shown to increase with logh, with a slopeof ~2 and a correlation coefficient equal to 0.75. This relation existsover a range of disc scalelengths from 0.5 to 10kpc(H0=75kms-1Mpc-1). In general, galaxytypes Scd or later are observed to deviate from this relation; they havefainter surface brightnesses for a given scalelength. With a subsampleof 59 low-inclination (i<=50°) and 29 high-inclination(i>=50°) galaxies having morphological types ranging from S0 toSc, the need for an inclination correction to the K-band disc surfacebrightness is demonstrated. Certain selection criteria biases which havetroubled previous surface brightness inclination tests (for example,whether the galaxies are selected from a magnitude- or diameter-limitedsample) do not operate in the μ0,K-logh diagram. Measuredcentral disc surface brightnesses are found to be significantly(>5σ) brighter for the high-inclination disc galaxies than forthe low-inclination disc galaxies. With no surface brightnessinclination correction or allowance for the trend betweenμ0,K and logh, the standard deviation to the distributionof μ0,K values is ~1magarcsec-2, while thestandard deviation about the mean μ0,K-logh relationdecreases from 0.69magarcsec-2, when no inclinationcorrection is applied, to 0.47magarcsec-2 when theinclination correction is applied. Possible changes to the discscalelength with inclination, as a result of radial gradients in thedisc opacity, have been explored. The maximum possible sizes for suchcorrections are too small to provide a valid explanation for thedifference between the low- and high-inclination disc galaxies in theμ0,K-logh diagram.
| 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.
| Correlations among Global Photometric Properties of Disk Galaxies
Using a two-dimensional galaxy image decomposition technique, we extractglobal bulge and disk parameters for a complete sample of early-typedisk galaxies in the near-infrared K band. We find significantcorrelation of the bulge parameter n with the central bulge surfacebrightness μb(0) and with effective radiusre. Using bivariate analysis techniques, we findthat logn, logre, and μb(0) are distributed ina plane with small scatter. We do not find a strong correlation of nwith bulge-to-disk luminosity ratio, contrary to earlier reports. Forthese early-type disk galaxies, re and the diskscale length rd are well correlated, but withlarge scatter. We examine the implications of our results for variousbulge formation scenarios in disk galaxies.
| Box- and peanut-shaped bulges. I. Statistics
We present a classification for bulges of a complete sample of ~ 1350edge-on disk galaxies derived from the RC3 (Third Reference Catalogue ofBright Galaxies, de Vaucouleurs et al. \cite{rc3}). A visualclassification of the bulges using the Digitized Sky Survey (DSS) inthree types of b/p bulges or as an elliptical type is presented andsupported by CCD images. NIR observations reveal that dust extinctiondoes almost not influence the shape of bulges. There is no substantialdifference between the shape of bulges in the optical and in the NIR.Our analysis reveals that 45% of all bulges are box- and peanut-shaped(b/p). The frequency of b/p bulges for all morphological types from S0to Sd is > 40%. In particular, this is for the first time that such alarge frequency of b/p bulges is reported for galaxies as late as Sd.The fraction of the observed b/p bulges is large enough to explain theb/p bulges by bars. Partly based on observations collected at ESO/LaSilla (Chile), DSAZ/Calar Alto (Spain), and Lowell Observatory/Flagstaff(AZ/U.S.A.). Tables 6 and 7 are only available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Galactic bulges from Hubble Space Telescope NICMOS observations: ages and dust
We present optical and near-infrared colour maps of the central regionsof bulges of S0 and spiral galaxies obtained with WFPC2 and NICMOS onthe Hubble Space Telescope (HST). By combined use of HST andground-based data, the colour information spans a region from a few tensof pc to a few kpc. In almost all galaxies, the colour profiles in thecentral 100-200pc become more rapidly redder. We attribute the highcentral colour indices to a central concentration of dust. We infer anaverage extinction at the centre of AV=0.6-1.0mag. Severalobjects show central dust rings or discs at subkpc scales similar tothose found by others in giant ellipticals. For galactic bulges of typesS0 to Sb, the tightness of the B-I versus I-H relation suggests that theage spread among bulges of early-type galaxies is small, at most 2Gyr.Colours at 1Reff, where we expect extinction to benegligible, are similar to those of elliptical galaxies in the Comacluster, suggesting that these bulges formed at the same time as thebright galaxies in Coma. Furthermore, the galaxy ages are found to beindependent of their environment. As it is likely that Coma was formedat redshift z>3, our bulges, which are in groups and in the field,must also have been formed at this epoch. Bulges of early-type spiralscannot be formed by secular evolution of bars at recent epochs, becausesuch bulges would be much younger. There are three galaxies of type Sbcand later; their bulges are younger and could perhaps arise from secularevolution of transient bars. Our results are in good agreement withsemi-analytic predictions, which also predict that bulges, in clustersand in the field, are as old as giant ellipticals in clusters.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The effects of a disc field on bulge surface brightness
Collisionless N-body simulations are used in an effort to reproduce theobserved tendency of the surface brightness profile of bulges to changeprogressively from an R exp 1/4 law to an exponential, going from early-to late-type spirals. A possible cause for this is the formation of thedisk later in the history of the galaxy, and this is simulated byapplying on the N-body bulge the force field of an exponential disk thesurface density of which increases with time. It is shown that n, theindex of the Sersic law that best describes the surface brightnessprofile, does indeed decrease from 4 (the de Vaucouleurs law) to smallervalues; this decrease is larger for more massive and more compact disks.A large part of the observed trend of n with B/D ratio is explained, andmany of the actual profiles can be matched exactly by the simulations.The correlation between the disk scale length and bulge effectiveradius, used recently to support the 'secular evolution' origin forbulges, is also shown to arise naturally in a scenario like this. Thismechanism, however, saturates at around n = 2 and exponential bulgescannot be produced; as n gets closer to 1, the profile becomesincreasingly robust against a disk field. These results provide strongsupport to the old-bulge hypothesis for the early-type bulges. Theexponential bulges, however, remain essentially unexplained; the resultshere suggest that they did not begin their lives as R exp 1/4 spheroids,and hence were probably formed, at least in part, by different processesfrom those of early-type spirals.
| Infrared Observations of Galaxies in the Local Universe. I. The Survey and Some Representative Results
This paper introduces a continuing survey of galaxies in the localuniverse. Consistent deep images are being acquired for a representativesample of 321 galaxies in the Uppsala General Catalogue down to 21.7 magarcsec-2 at Ks (2.16 mu m) and 22.4 mag arcsec-2 at J (1.25 mu m) usinga NICMOS camera with a 3.'8 x 3.'8 field of view attached to the 61 inch(1.5 m) telescope on Mount Bigelow. We provide some examples of theresults being obtained by employing 64 deep images of a subset of 44galaxies. Bulge-to-disk ratios are tabulated for 30 galaxies. Thebrightness of the central region of 44 galaxies declines approximately 5mag from Hubble type S0 to Sm. An exponential vertical scale height atKs is found to be 500 pc for the disk of UGC 5173. Arm amplitudes offour nearly face-on spiral galaxies are found to range between 11% and88% compared to the interarm region. There is some evidence that the armamplitude is larger at Ks than it is at J. Color gradients are measuredfor 15 galaxies with only one showing a significant nonzero result. Ameasurement of galactic symmetry applied to 64 deep images reveals anaverage asymmetry of 7.6% ( sigma = 4.6%) for these galaxies.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| Near-infrared surface photometry of bulges and disks of spiral galaxies. The data
We present optical and near-infrared (NIR) surface brightness and colourprofiles, in bands ranging from U to K, for the disk and bulgecomponents of a complete sample of 30 nearby S0 to Sbc galaxies withinclinations larger than 50 deg. We describe in detail the observationsand the determination of colour parameters. Calibrated monochromatic andreal-colour images are presented, as well as colour index maps. Thisdata set, tailored for the study of the population characteristics ofgalaxy bulges, provides useful information on the colours of inner disksas well. In related papers, we have used them to quantify colourgradients in bulges, and age differentials between bulge and inner disk.
| Ages of Galaxies Bulges and Disks From Optical and Near-Infrared Colors
We compare optical and near-infrared colors of disks and bulges in adiameter-limited sample of inclined, bright, nearby, early-type spirals.Color profiles along wedge apertures at 15^deg^ from the major axis andon the minor axis on the side of the galaxy opposite to the dust laneare used to assign nominal colors for the inner disks (at 2 scalelength) and for the bulges (~0.5r_eff_), respectively. We estimate thatthe effects of dust reddening and the cross-talk between the colors ofthe two components is negligible. We find that color differences(bulge-disk) are very small: {DELTA}(U-R) = 0.126+/-0.165,{DELTA}(R-K)=0078+/-0.165. Disks tend to be bluer by an amount threetimes smaller than that reported by Bothun & Gregg [ApJ,350,73(1990)] for S0s. Color variations from galaxy to galaxy are muchlarger than color differences between disk and bulge in each galaxy.Probably, the underlying old population of disks and bulges is much moresimilar than the population paradigm would lead us to believe. Impliedage differences, assuming identical metallicities, are less than 30%.
| Global H I profiles of spiral galaxies.
In this paper we present short H I synthesis observations of 57 galaxieswithout H I information in the RC3. These are a by-product of a largesurvey with the WSRT of the neutral hydrogen gas in spiral and irregulargalaxies. Global profiles and related quantities are given for the 42detected galaxies and upper limits for the remaining 15. A number ofgalaxies have low values of H I mass-to-blue luminosity ratio.
| The Shape of the Luminosity Profiles of Bulges of Spiral Galaxies
Using a 2D generalization of Kent's model-independent decompositionmethod, we extract the K-band light profiles of the bulges of a sampleof field galaxies with morphological types ranging from S0 to Sbc. Wethen examine the shape of the bulge profiles, by means of fitting aseeing-convolved power law of the form μ(r) is proportional tor^1/n^, where the exponent n is allowed to vary. The best-fittingexponent n is found to vary systematically from values around 1(exponential) to 6 from late- to early- type bulges; the profiles tendto fall off more steeply in the outer parts for the later types. Thesame trend is seen as a function of bulge to disc ratio. Application ofthe method to artificial data proves that this result is not caused bydisc-light contamination. There are also indications that n becomeslarger with increasing total luminosity and radius of the bulge. Asimilar relation has recently been found for elliptical galaxies. Thesmooth trend of n with morphological type shows that the formation of orinteraction with the disc has affected the density distribution of thebulge.
| Colors and color gradients in bulges of galaxies
We have obtained surface photometry in U, B, R, and I for a completeoptically selected sample of 45 early-type spiral galaxies, toinvestigate the colors and color gradients of spiral bulges. Colorprofiles in U-R, B-R, U-B, and R-I have been determined in wedgesopening on the semiminor axes. Based on several criteria, like thesmoothness of the color profiles, the absence of dust lanes, and thecentral colors, we have defined a subsample of 18 objects whose colorsare largely unaffected by dust. We believe such colors are suitable forinferring properties of the stellar populations of bulges. We find thatthe colors of bulges are predominantly bluer than those of ellipticals.This result holds even when bulges are compared to ellipticals of thesame luminosity, and indicates that bulges are younger and/or more metalpoor than old elliptical galaxies. Most bulges do not reach solarmetallicities. Bulges show predominantly negative color gradients (blueroutward). For bright bulges (MBulgeR is less than-20.0), the magnitude of the gradient increases with bulge luminosity.For fainter bulges, gradients scatter around large negative values. Thebehavior of color gradients as a function of bulge luminosity suggestsdifferent formation mechanisms for faint and bright spheroids. Forbright bulges, the scaling of gradients with luminosity suggests aformation process involving dissipation. The similarity with ellipticalssuggests that the formation of the disk did not affect the stellarpopulations of the bulge in a major way. For small bulges (MRis greater than -20), the existence of pronounced color gradientssuggests a different formation mechanism. For these objects, thepresence of the disk may have severely affected the radial populationdistribution in the bulge.
| 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.
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| Box-shaped galaxies - A complete list
A survey of box-shaped galaxies complete to B(tau) = 13.2 in the wholesky is presented, consisting of 74 objects, 60 of which are newidentifications. The observed frequency of lenticulars exhibiting thisphenomenon is shown to be consistent with the hypothesis of their beingedge-on barred galaxies. A sequence noted in the morphology of thebox-shaped bulges is thought to be related to the global dynamicalstructure of these galaxies.
| A search for environmental effects on the optical properties of galaxies in groups
Environmental density-related modifications of basic optical properties(luminosities, sizes, axial ratios, and colors) of galaxies belonging toGeller and Huchra's (1983) groups have been investigated. Remarkably, itis found that the broad maxima of the distributions of luminosities anddiameters of spirals and the whole corresponding distributions oflenticulars tend to move to lower values as one goes to groups of highcompactness, whereas the luminosity-diameter relationship of spiralstends to become flatter. No color and axial ratio differences betweengalaxies of high- and low-compactness groups have been detected.
| A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
| A catalog of hierarchical subclustering in the Turner-Gott groups
Information on the substructure, to four levels of hierarchy, ispresented for the 103 groups listed by Turner and Gott (TG) in theircatalog of groups of galaxies. All galaxies brighter than Mpg= 14.0 in the region delta is 0 deg or greater and b(II) is 40 deg orgreater that have been assigned group memberships by TG are included.Also listed is the local environmental information for each of thegalaxies, giving the surface density enhancement beta in the galaxy'sneighborhood, calculated at 15 levels in the range beta = 4.6 to 10,000.
| Flocculent and grand design spiral structure in field, binary and group galaxies
A 12-division morphological system emphasizing arm continuity, lengthand symmetry has been developed for the classification of all spiralgalaxies according to the regularity of their spiral arm structure. Armclassifications were tabulated for 305 barred and nonbarred spiralgalaxies; of these, 79 are isolated, 52 are binary and 174 are ingroups. Among the isolated SA galaxies, 68 + or - 10% have irregular andfragmented, or 'flocculent', spiral structures. Only 32 + or - 10% havesymmetric spiral arms in the classic grand design pattern. Flocculentspirals are the most common structures of galaxies without companions orbars. Since flocculent galaxies may have bars and companions, and granddesign galaxies may have neither bars nor companions, such perturbationsare neither perfectly effective nor always necessary in the driving ofgrand design patterns.
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