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The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
The ACS Virgo Cluster Survey is a Hubble Space Telescope program toobtain high-resolution imaging in widely separated bandpasses (F475W~gand F850LP~z) for 100 early-type members of the Virgo Cluster, spanninga range of ~460 in blue luminosity. We use this large, homogenous dataset to examine the innermost structure of these galaxies and tocharacterize the properties of their compact central nuclei. We presenta sharp upward revision in the frequency of nucleation in early-typegalaxies brighter than MB~-15 (66%<~fn<~82%)and show that ground-based surveys underestimated the number of nucleidue to surface brightness selection effects, limited sensitivity andpoor spatial resolution. We speculate that previously reported claimsthat nucleated dwarfs are more concentrated toward the center of Virgothan their nonnucleated counterparts may be an artifact of theseselection effects. There is no clear evidence from the properties of thenuclei, or from the overall incidence of nucleation, for a change atMB~-17.6, the traditional dividing point between dwarf andgiant galaxies. There does, however, appear to be a fundamentaltransition at MB~-20.5, in the sense that the brighter,``core-Sérsic'' galaxies lack resolved (stellar) nuclei. A searchfor nuclei that may be offset from the photocenters of their hostgalaxies reveals only five candidates with displacements of more than0.5", all of which are in dwarf galaxies. In each case, however, theevidence suggests that these ``nuclei'' are, in fact, globular clustersprojected close to the galaxy photocenter. Working from a sample of 51galaxies with prominent nuclei, we find a median half-light radius of=4.2 pc, with the sizes of individual nucleiranging from 62 pc down to <=2 pc (i.e., unresolved in our images) inabout a half-dozen cases. Excluding these unresolved objects, the nucleisizes are found to depend on nuclear luminosity according to therelation rh L0.50+/-0.03. Because the largemajority of nuclei are resolved, we can rule out low-level AGNs as anexplanation for the central luminosity excess in almost all cases. Onaverage, the nuclei are ~3.5 mag brighter than a typical globularcluster. Based on their broadband colors, the nuclei appear to have oldto intermediate age stellar populations. The colors of the nuclei ingalaxies fainter than MB~-17.6 are tightly correlated withtheir luminosities, and less so with the luminosities of their hostgalaxies, suggesting that their chemical enrichment histories weregoverned by local or internal factors. Comparing the nuclei to the``nuclear clusters'' found in late-type spiral galaxies reveals a closematch in terms of size, luminosity, and overall frequency. A formationmechanism that is rather insensitive to the detailed properties of thehost galaxy properties is required to explain this ubiquity andhomogeneity. The mean of the frequency function for thenucleus-to-galaxy luminosity ratio in our nucleated galaxies,=-2.49+/-0.09 dex (σ=0.59+/-0.10), isindistinguishable from that of the SBH-to-bulge mass ratio,=-2.61+/-0.07dex (σ=0.45+/-0.09), calculated in 23 early-type galaxies withdetected supermassive black holes (SBHs). We argue that the compactstellar nuclei found in many of our program galaxies are the low-masscounterparts of the SBHs detected in the bright galaxies. If thisinterpretation is correct, then one should think in terms of ``centralmassive objects''-either SBHs or compact stellar nuclei-that accompanythe formation of almost all early-type galaxies and contain a meanfraction ~0.3% of the total bulge mass. In this view, SBHs would be thedominant formation mode above MB~-20.5.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.
| The ACS Virgo Cluster Survey. IX. The Color Distributions of Globular Cluster Systems in Early-Type Galaxies
We present the color distributions of globular cluster (GC) systems for100 early-type galaxies observed in the ACS Virgo Cluster Survey, thedeepest and most homogeneous survey of this kind to date. On average,galaxies at all luminosities in our study (-22
| The ACS Virgo Cluster Survey. X. Half-Light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation
We have measured half-light radii, rh, for thousands ofglobular clusters (GCs) belonging to the 100 early-type galaxiesobserved in the ACS Virgo Cluster Survey and the elliptical galaxy NGC4697. An analysis of the dependencies of the measured half-light radiion both the properties of the GCs themselves and their host galaxiesreveals that, in analogy with GCs in the Galaxy but in a milder fashion,the average half-light radius increases with increasing galactocentricdistance or, alternatively, with decreasing galaxy surface brightness.For the first time, we find that the average half-light radius decreaseswith the host galaxy color. We also show that there is no evidence for avariation of rh with the luminosity of the GCs. Finally, wefind in agreement with previous observations that the averagerh depends on the color of GCs, with red GCs being ~17%smaller than their blue counterparts. We show that this difference isprobably a consequence of an intrinsic mechanism, rather than projectioneffects, and that it is in good agreement with the mechanism proposed byJordán. We discuss these findings in light of two simple picturesfor the origin of the rh of GCs and show that both lead to abehavior in rough agreement with the observations. After accounting forthe dependencies on galaxy color, galactocentric radius, and underlyingsurface brightness, we show that the average GC half-light radii can be successfully used as a standard ruler fordistance estimation. We outline the methodology, provide a calibrationfor its use, and discuss the prospects for this distance estimator withfuture observing facilities. We find =2.7+/-0.35 pcfor GCs with (g-z)=1.2 mag in a galaxy with color(g-z)gal=1.5 mag and at an underlying surface z-bandbrightness of μz=21 mag arcsec-2. Using thistechnique, we place an upper limit of 3.4 Mpc on the 1 σline-of-sight depth of the Virgo Cluster. Finally, we examine the formof the rh distribution for our sample galaxies and provide ananalytic expression that successfully describes this distribution.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 NAS 5-26555.
| The relationship between the Sérsic law profiles measured along the major and minor axes of elliptical galaxies
In this paper we discuss the reason why the parameters of theSérsic model best-fitting the major axis light profile ofelliptical galaxies can differ significantly from those derived for theminor axis profile. We show that this discrepancy is a naturalconsequence of the fact that the isophote eccentricity varies with theradius of the isophote and present a mathematical transformation thatallows the minor axis Sérsic model to be calculated from themajor axis model, provided that the elliptical isophotes are aligned andconcentric and that their eccentricity can be represented by a wellbehaved, though quite general, function of the radius. When there is novariation in eccentricity only the effective radius changes in theSérsic model, while for radial-dependent eccentricity thetransformation, which allows the minor axis Sérsic model to becalculated from the major axis model is given by the Lerch Φtranscendental function. The proposed transformation was tested usingphotometric data for 28 early-type galaxies.
| The ACS Virgo Cluster Survey. II. Data Reduction Procedures
The ACS Virgo Cluster Survey is a large program to carry out multicolorimaging of 100 early-type members of the Virgo Cluster using theAdvanced Camera for Surveys (ACS) on the Hubble Space Telescope. DeepF475W and F850LP images (~SDSS g and z) are being used to study thecentral regions of the program galaxies, their globular cluster systems,and the three-dimensional structure of Virgo itself. In this paper, wedescribe in detail the data reduction procedures used for the survey,including image registration, drizzling strategies, the computation ofweight images, object detection, the identification of globular clustercandidates, and the measurement of their photometric and structuralparameters.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 NAS 5-26555.
| The ACS Virgo Cluster Survey. I. Introduction to the Survey
The Virgo Cluster is the dominant mass concentration in the LocalSupercluster and the largest collection of elliptical and lenticulargalaxies in the nearby universe. In this paper, we present anintroduction to the ACS Virgo Cluster Survey: a program to image, in theF475W and F850LP bandpasses (~Sloan g and z), 100 early-type galaxies inthe Virgo Cluster using the Advanced Camera for Surveys on the HubbleSpace Telescope. We describe the selection of the program galaxies andtheir ensemble properties, the choice of filters, the field placementand orientation, the limiting magnitudes of the survey, coordinatedparallel observations of 100 ``intergalactic'' fields with WFPC2, andsupporting ground-based spectroscopic observations of the programgalaxies. In terms of depth, spatial resolution, sample size, andhomogeneity, this represents the most comprehensive imaging survey todate of early-type galaxies in a cluster environment. We brieflydescribe the main scientific goals of the survey, which include themeasurement of luminosities, metallicities, ages, and structuralparameters for the many thousands of globular clusters associated withthese galaxies, a high-resolution isophotal analysis of galaxiesspanning a factor of ~450 in luminosity and sharing a commonenvironment, the measurement of accurate distances for the full sampleof galaxies using the method of surface brightness fluctuations, and adetermination of the three-dimensional structure of Virgo itself.ID="FN1"> 1Based on observations with the NASA/ESA Hubble SpaceTelescope obtained at the Space Telescope Science Institute, which isoperated by the association of Universities for Research in Astronomy,Inc., under NASA contract NAS 5-26555.
| Companions of Bright Barred Shapley-Ames Galaxies
Companion galaxy environment for a subset of 78 bright and nearby barredgalaxies from the Shapley-Ames Catalog is presented. Among the spiralbarred galaxies, there are Seyfert galaxies, galaxies with circumnuclearstructures, galaxies not associated with any large-scale galaxy cloudstructure, galaxies with peculiar disk morphology (crooked arms), andgalaxies with normal disk morphology; the list includes all Hubbletypes. The companion galaxy list includes the number of companiongalaxies within 20 diameters, their Hubble type, and projectedseparation distance. In addition, the companion environment was searchedfor four known active spiral galaxies, three of them are Seyfertgalaxies, namely, NGC 1068, NGC 1097, and NGC 5548, and one is astarburst galaxy, M82. Among the results obtained, it is noted that theonly spiral barred galaxy classified as Seyfert 1 in our list has nocompanions within a projected distance of 20 diameters; six out of 10Seyfert 2 bar galaxies have no companions within 10 diameters, six outof 10 Seyfert 2 galaxies have one or more companions at projectedseparation distances between 10 and 20 diameters; six out of 12 galaxieswith circumnuclear structures have two or more companions within 20diameters.
| 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
| The `Photometric Plane' of elliptical galaxies
The Sérsic (r1/n) index n of an elliptical galaxy (orbulge) has recently been shown to correlate strongly (r= 0.8) with thecentral velocity dispersion of a galaxy. This index could thereforeprove extremely useful and cost-effective (in terms of both telescopetime and data reduction) for many fields of extragalactic research. Itis a purely photometric quantity which apparently not only traces themass of a bulge but has additionally been shown to reflect the degree ofbulge concentration. This paper explores the affect of replacing thecentral velocity dispersion term in the Fundamental Plane with theSérsic index n. Using a sample of early-type galaxies from theVirgo and Fornax clusters, various (B-band) `Photometric Planes' wereconstructed and found to have a scatter of 0.14-0.17 dex in logre, or a distance error of 38-48 per cent per galaxy (thehigher values arising from the inclusion of the S0 galaxies). Thecorresponding Fundamental Plane yielded a 33-37 per cent error indistance for the same galaxy samples (i.e. ~15-30 per cent lessscatter). The gains in using a hyperplane (i.e. adding the Sérsicindex to the Fundamental Plane as a fourth parameter) were small, givinga 27-33 per cent error in distance, depending on the galaxy sample used.The Photometric Plane has been used here to estimate the Virgo-Fornaxdistance modulus; giving a value of 0.62 +/- 0.30 mag[cf. 0.51 +/- 0.21,Hubble Space Telescope (HST) Key Project on the Extragalactic DistanceScale]. The prospects for using the Photometric Plane at higherredshifts appears promising. Using published data on the intermediateredshift cluster Cl 1358 + 62 (z= 0.33) gave a Photometric Planedistance error of 35-41 per cent per galaxy.
| 1.65-μm (H -band) surface photometry of galaxies - VIII. The near-IR κ space at z =0
We present the distribution of a statistical sample of nearby galaxiesin the κ -space (κ 1 ~logM , κ 2~logI e 3 M /L , κ 3 ~logM /L ).Our study is based on near-IR (H -band: λ =1.65μm)observations, for the first time comprising early- and late-typesystems. Our data confirm that the mean effective dynamicalmass-to-light ratio M /L of the E+S0+S0a galaxies increases withincreasing effective dynamical mass M , as expected from the existenceof the Fundamental Plane relation. Conversely, spiral and Im/BCDgalaxies show a broad distribution in M /L with no detected trend of M/L with M , the former galaxies having M /L values about twice largerthan the latter, on average. For all the late-type galaxies, the M /Lincreases with decreasing effective surface intensity I e ,consistent with the existence of the Tully-Fisher relation. Theseresults are discussed on the basis of the assumptions behind theconstruction of the κ -space and their limitations. Our study iscomplementary to a previous investigation in the optical (B -band:λ =0.44μm) and allows us to study wavelength dependences ofthe galaxy distribution in the κ -space. As a first result, wefind that the galaxy distribution in the κ 1 -κ2 plane reproduces the transition from bulgeless tobulge-dominated systems in galaxies of increasing dynamical mass.Conversely, it appears that the M /L of late-types is higher (lower)than that of early-types with the same M in the near-IR (optical). Theorigins of this behaviour are discussed in terms of dust attenuation andstar formation history.
| 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.
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| Total Magnitudes of Virgo Galaxies. I. Construction of a Self-Consistent Reference Dataset Spanning 8th to 18th Magnitude
The main objectives of this series of papers are: (1) to demonstrate theexistence of serious mutual disagreements between established total (andother integrated) magnitude scales for Virgo galaxies; (2) to attempt toquantify both the systematic and random errors present within thesemagnitude scales; (3) to investigate the origins of any large erroruncovered; and thereby (4) to encourage the general adoption of rigoroustotal-magnitude measurement procedures by the astronomical community.The ramifications of the findings presented in this series of paperswill be discussed in detail at a later date. In this paper, the first inthe series, a self-consistent dataset of trustworthy total-magnitudemeasurements is compiled for a sample of Virgo galaxies spanning a rangeof 10 000 in apparent brightness, based on only the most reliablemeasurements and photometry currently available. This reference dataset,which includes luminosity profile shape information, will be used insubsequent papers as one of the bases for assessing existing magnitudescales for Virgo galaxies. As most published magnitudes are based onB-band observations, this series of papers will also focus primarily onB-band measurements.
| 2D modelling of the light distribution of early-type galaxies in a volume-limited sample - II. Results for real galaxies
In this paper we analyse the results of the two-dimensional (2D) fit ofthe light distribution of 73 early-type galaxies belonging to the Virgoand Fornax clusters, a sample volume- and magnitude-limited down toMB=-17.3, and highly homogeneous. In our previous paper(Paper I) we have presented the adopted 2D models of thesurface-brightness distribution - namely the r1/n and(r1/n+exp) models - we have discussed the main sources oferror affecting the structural parameters, and we have tested theability of the chosen minimization algorithm (MINUIT) in determining thefitting parameters using a sample of artificial galaxies. We show that,with the exception of 11 low-luminosity E galaxies, the best fit of thereal galaxy sample is always achieved with the two-component(r1/n+exp) model. The improvement in the χ2due to the addition of the exponential component is found to bestatistically significant. The best fit is obtained with the exponent nof the generalized r1/n Sersic law different from theclassical de Vaucouleurs value of 4. Nearly 42 per cent of the samplehave n<2, suggesting the presence of exponential `bulges' also inearly-type galaxies. 20 luminous E galaxies are fitted by thetwo-component model, with a small central exponential structure (`disc')and an outer big spheroid with n>4. We believe that this is probablydue to their resolved core. The resulting scalelengths Rh andRe of each component peak approximately at ~1 and ~2kpc,respectively, although with different variances in their distributions.The ratio Re/Rh peaks at ~0.5, a value typical fornormal lenticular galaxies. The first component, represented by ther1/n law, is probably made of two distinct families,`ordinary' and `bright', on the basis of their distribution in theμe-log(Re) plane, a result already suggested byCapaccioli, Caon and D'Onofrio. The bulges of spirals and S0 galaxiesbelong to the `ordinary' family, while the large spheroids of luminous Egalaxies form the `bright' family. The second component, represented bythe exponential law, also shows a wide distribution in theμ0c-log(Rh) plane. Small discs (orcores) have short scalelengths and high central surface brightness,while normal lenticulars and spiral galaxies generally have scalelengthshigher than 0.5kpc and central surface brightness brighter than20magarcsec-2 (in the B band). The scalelengths Reand Rh of the `bulge' and `disc' components are probablycorrelated, indicating that a self-regulating mechanism of galaxyformation may be at work. Alternatively, two regions of theRe-Rh plane are avoided by galaxies due todynamical instability effects. The bulge-to-disc (B/D) ratio seems tovary uniformly along the Hubble sequence, going from late-type spiralsto E galaxies. At the end of the sequence the ratio between the largespheroidal component and the small inner core can reach B/D~100.
| Line-of-sight velocity distributions of low-luminosity elliptical galaxies
The shape of the line-of-sight velocity distribution (LOSVD) is measuredfor a sample of 14 elliptical galaxies, predominantly low-luminosityellipticals. The sample is dominated by galaxies in the Virgo clusterbut also contains ellipticals in nearby groups and low-densityenvironments. The parametrization of the LOSVD given by Gerhard and vander Marel & Franx is adopted, which measures the asymmetrical andsymmetrical deviations of the LOSVD from a Gaussian by the amplitudesh3 and h4 of the Gauss-Hermite series. Rotation,velocity dispersion, h3 and h4 are determined as afunction of radius for both major and minor axes. Non-Gaussian LOSVDsare found for all galaxies along the major axes. Deviations from aGaussian LOSVD along the minor axis are of much lower amplitude ifpresent at all. Central decreases in velocity dispersion are found forthree galaxies. Two galaxies have kinematically decoupled cores: NGC4458and the well-known case of NGC3608.
| 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.
| 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
| 1.65 μm (H-band) surface photometry of galaxies. III. observations of 558 galaxies with the TIRGO 1.5 m telescope
We present near-infrared H-band (1.65 μm ) surface photometry of 558galaxies in the Coma Supercluster and in the Virgo cluster. This dataset, obtained with the Arcetri NICMOS3 camera ARNICA mounted on theGornergrat Infrared Telescope, is aimed at complementing, withobservations of mostly early-type objects, our NIR survey of spiralgalaxies in these regions, presented in previous papers of this series.Magnitudes at the optical radius, total magnitudes, isophotal radii andlight concentration indices are derived. We confirm the existence of apositive correlation between the near-infrared concentration index andthe galaxy H-band luminosity Based on observations taken at TIRGO(Gornergrat, Switzerland). TIRGO is operated by CAISMI-CNR, Arcetri,Firenze, Italy. Tables 1 and 2 are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 1.65 μm (H-band) surface photometry of galaxies. V. Profile decomposition of 1157 galaxies
We present near-infrared H-band (1.65 μm) surface brightness profiledecomposition for 1157 galaxies in five nearby clusters of galaxies:Coma, A1367, Virgo, A262 and Cancer, and in the bridge between Coma andA1367 in the ``Great Wall". The optically selected (mpg≤16.0) sample is representative of all Hubble types, from E to Irr+BCD,except dE and of significantly different environments, spanning fromisolated regions to rich clusters of galaxies. We model the surfacebrightness profiles with a de Vaucouleurs r1/4 law (dV), withan exponential disk law (E), or with a combination of the two (B+D).From the fitted quantities we derive the H band effective surfacebrightness (μe) and radius (re) of each component, theasymptotic magnitude HT and the light concentration indexC31. We find that: i) Less than 50% of the Ellipticalgalaxies have pure dV profiles. The majority of E to Sb galaxies is bestrepresented by a B+D profile. All Scd to BCD galaxies have pureexponential profiles. ii) The type of decomposition is a strong functionof the total H band luminosity (mass), independent of the Hubbleclassification: the fraction of pure exponential decompositionsdecreases with increasing luminosity, that of B+D increases withluminosity. Pure dV profiles are absent in the low luminosity rangeLH<1010 L\odot and become dominantabove 1011 L\odot . Based on observations taken atTIRGO, Gornergrat, Switzerland (operated by CAISMI-CNR, Arcetri,Firenze, Italy) and at the Calar Alto Observatory (operated by theMax-Planck-Institut für Astronomie (Heidelberg) jointly with theSpanish National Commission for Astronomy). Table 2 and Figs. 2, 3, 4are available in their entirety only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| At the Heart of Barred Galaxies
Not Available
| The 3D structure of the Virgo cluster from H-band Fundamental Plane and Tully-Fisher distance determinations
We undertook a surface photometry survey of 200 galaxies in the Virgocluster (complete to B<14.0 mag) carried out in the near-infrared(NIR) H band. Combining velocity dispersion measurements from theliterature with new spectroscopic data for 11 galaxies, we derivedistances of 59 early-type galaxies using the Fundamental Plane (FP)method. The distances of another 75 late-type galaxies are determinedusing the Tully-Fisher (TF) method. For this purpose we use the maximumrotational velocity, as derived from HI spectra from the literature,complemented with new Hα rotation curves of eight highlyHI-deficient galaxies. The zero-points of the FP and TF templaterelations are calibrated assuming the distance modulus of Virgomu_0=31.0, as determined with the Cepheids method. Using these 134distance determinations (with individual uncertainties of 0.35 mag (TF)and 0.45 mag (FP)) we find that the distance of cluster A, associatedwith M87, is mu_0=30.84 +/- 0.06. Cluster B, offset to the south, isfound at mu_0=31.84 +/- 0.10. This subcluster is falling on to A atabout 750 km s^-1. Clouds W and M are at twice the distance of A.Galaxies on the north-west and south-east of the main cluster A belongto two clouds composed almost exclusively of spiral galaxies withdistances consistent with A, but with significantly different velocitydistributions, suggesting that they are falling on to cluster A atapproximately 770 km s^-1 from the far side and at 200 km s^-1 from thenear side respectively. The mass of Virgo inferred from the peculiarmotions induced on its vicinity is consistent with the virialexpectation.
| 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.
| Nuclear stellar discs in early-type galaxies - II. Photometric properties
Hubble Space Telescope images of two early-type galaxies harbouring bothnuclear and outer stellar discs are studied in detail. By means of aphotometric decomposition, the images of NGC 4342 and 4570 are analysedand the photometric properties of the nuclear discs investigated. Wefind a continuity of properties in the parameter space defined by thecentral surface brightness mu_0 and the scalelength R_d of discs inspirals, S0s and embedded discs in ellipticals, in the sense that thenuclear discs extend the observed disc properties even further towardssmaller scalelengths and brighter central surface brightnesses. Whenincluding the nuclear discs, disc properties span more than four ordersof magnitude in both scalelength and central surface brightness. Thenuclear discs studied here are the smallest and brightest stellar discsknown, and as such, they are as extreme in their photometric propertiesas Malin I, when compared with typical galactic discs that obeyFreeman's law. We discuss a possible formation scenario in which thedouble-disc structure observed in these galaxies has been shaped by nowdissolved bars. Based on the fact that the black holes known to exist insome of these galaxies have masses comparable to those of the nucleardiscs, we explore a possible link between the black holes and thenuclear discs.
| Some effects of galaxy structure and dynamics on the Fundamental Plane - II. A Virgo-Fornax distance modulus
The influence of broken structural homology, and the implied brokendynamical homology, is examined for the Fundamental Plane (FP).Requiring a symmetrical treatment of the FP variables, a bisector methodof linear regression was applied, in three dimensions, to derive thebest FP. A bootstrapping procedure has been used to estimate theuncertainties associated with the slope of the FP. For 25 E and S0 Virgogalaxies, the `standard' FP, constructed using R^1/4 model parametersfor the effective radii (R_e,4) and the mean surface brightness withinthis radius (Sigma_e,4) and using central velocity dispersion (CVD)measurements (sigma_0), gave a relation described by R_e, 4~sigma_0^1.10+/-0.14Sigma_e,4 ^-0.55+/-0.09. Using Sersic R^1/n light-profilemodel parameters and the projected infinite-aperture velocity dispersion(sigma_tot,n), derived from application of the Jeans equation to theobserved intensity profiles, gave an `improved' FP described by therelation R_e,n~sigma _tot,n^1.37+/-0.16 Sigma _e,n^-0.76+/-0.05. Thisresult, based on independent data, supports the previous finding byGraham & Colless that assumptions of structural and dynamicalhomology are partly responsible for the departure of the observed FPfrom the plane expected by the virial theorem, which predictsR~sigma^2Sigma^-1. Upon removal of the known S0 galaxies from the sampleof Virgo galaxies, the above planes were observed to change toR_e,4~sigma _0^1.19+/-0.21Sigma _e,4^-0.60+/-0.11 and R_e,n~sigma_tot,n^1.72+/-0.24Sigma_e,n ^-0.74+/-0.09. The perpendicular rms residualsabout these planes are 0.084 and 0.050 dex, respectively. The Fornaxcluster was similarly treated, although removal of the S0 galaxies lefta sample of only seven ellipticals that had published CVD measurements.Treating the range of structural and dynamical profiles present in thissample produced a FP given by the relation R_e,n~sigma_tot,n^2.03+/-0.78Sigma_e,n ^-1.07+/-0.30, in tantalizing agreement with theplane expected from the virial theorem, but with discouragingly largeerrors caused by the small sample size. Similarly to Virgo, theperpendicular rms residual about this plane is 0.050 dex. The FP wasalso constructed with the purpose of using it as a distance indicator,achieved by minimizing the distance-dependent quantity log R against thedistance-independent quantities Sigma and log sigma. A Virgo-Fornaxdistance modulus was computed using Working-Hotelling confidence bands.The `standard' FP parameters gave a value of 0.45+/-0.16 mag, whereasthe `improved' FP parameters gave a value of 0.25+/-0.12 mag. However, afull treatment of the uncertainties on the FP slopes, derived through abootstrapping procedure of the three-dimensional FP data set, revealedthat the analytical expressions for the uncertainties on the estimateddistance moduli given above should be increased by a factor of ~5.
| A Complete Redshift Survey to the Zwicky Catalog Limit in a 2^h X 15 deg Region around 3C 273
We compile 1113 redshifts (648 new measurements, 465 from theliterature) for Zwicky catalog galaxies in the region (-3.5d <= delta<= 8.5d, 11h5 <= alpha <= 13h5). We include redshifts for 114component objects in 78 Zwicky catalog multiplets. The redshift surveyin this region is 99.5% complete to the Zwicky catalog limit, m_Zw =15.7. It is 99.9% complete to m_Zw = 15.5, the CfA Redshift Survey(CfA2) magnitude limit. The survey region is adjacent to the northernportion of CfA2, overlaps the northernmost slice of the Las CampanasRedshift Survey, includes the southern extent of the Virgo Cluster, andis roughly centered on the QSO 3C 273. As in other portions of theZwicky catalog, bright and faint galaxies trace the same large-scalestructure.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| 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.
| A catalogue of Mg_2 indices of galaxies and globular clusters
We present a catalogue of published absorption-line Mg_2 indices ofgalaxies and globular clusters. The catalogue is maintained up-to-datein the HYPERCAT database. The measurements are listed together with thereferences to the articles where the data were published. A codeddescription of the observations is provided. The catalogue gathers 3541measurements for 1491 objects (galaxies or globular clusters) from 55datasets. Compiled raw data for 1060 galaxies are zero-point correctedand transformed to a homogeneous system. Tables 1, 3, and 4 areavailable in electronic form only at the CDS, Strasbourg, via anonymousftp 130.79.128.5. Table 2 is available both in text and electronic form.
| 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.
| Artefacts in the deconvolution of images of E-S0 galaxies.
Unexpected circumnuclear isophotal structures were observed during testsof Lucy's deconvolution technique, performed upon high resolution CFHTframes. They contain an enhanced nuclear disk surrounded by a "boxy"ring; an upward hump in ellipticity corresponds with this ring. Suchstructures are produced in the deconvolution of synthetic images havinglarge enough surface brightness gradients and ellipticities, as is thecase for two of our test galaxies. Similar stuctures occur in convolvingand deconvolving model galaxies with a model of the HST's PSF prior tothe telescope renovation, but they are limited in radial extent up toless than 1 arcsec of isophotal major axis. If the deconvolution isperformed with a PSF differing somewhat from the one used in theconvolution, large and far extending artefacts can occur.
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