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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.
| The neutral hydrogen content of Fornax cluster galaxies
We present a new set of deep H I observations of member galaxies of theFornax cluster. We detected 35 cluster galaxies in HI. The resulting sample, the most comprehensive to date, is used toinvestigate the distribution of neutral hydrogen in the clustergalaxies. We compare the H I content of the detected cluster galaxieswith that of field galaxies by measuring H I mass-to-light ratios andthe H I deficiency parameter of Solanes et al. (\cite{Sol96}). The meanH I mass-to-light ratio of the cluster galaxies is 0.68+/- 0.15,significantly lower than for a sample of H I-selected field galaxies(1.15+/- 0.10), although not as low as in the Virgocluster (0.45+/- 0.03). In addition, the H I content of twocluster galaxies (NGC 1316C and NGC1326B) appears to have been affected by interactions. The meanH I deficiency for the cluster is 0.38+/-0.09 (for galaxy types T=1-6),significantly greater than for the field sample (0.05+/-0.03). Boththese tests show that Fornax cluster galaxies are HI-deficient compared to field galaxies. The kinematics of the clustergalaxies suggests that the H I deficiency may be caused by ram-pressurestripping of galaxies on orbits that pass close to the cluster core. Wealso derive the most complete B-band Tully - Fisher relation of inclinedspiral galaxies in Fornax. A subcluster in theSouth-West of the main cluster contributes considerably to the scatter.The scatter for galaxies in the main cluster alone is 0.50 mag, which isslightly larger than the intrinsic scatter of 0.4 mag. We use the Tully- Fisher relation to derive a distance modulus ofFornax relative to the Virgocluster of -0.38+/- 0.14 mag. The galaxies in the subclusterare (1.0+/-0.5) mag brighter than the galaxies of the main cluster,indicating that they are situated in the foreground. With their meanvelocity 95 km s-1 higher than that of the main cluster weconclude that the subcluster is falling into the main Fornaxcluster.
| 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.
| The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXII. The Discovery of Cepheids in NGC 1326A
We report on the detection of Cepheids and the first distancemeasurement to the spiral galaxy NGC 1326A, a member of the FornaxCluster of galaxies. We have employed data obtained with the Wide Fieldand Planetary Camera 2 on board the Hubble Space Telescope. Over a 49day interval, a total of 12 V-band (F555W) and eight I-band (F814W)epochs of observation were obtained. Two photometric reduction packages,ALLFRAME and DoPHOT, have been employed to obtain photometry measuresfrom the three Wide Field CCDs. Variability analysis yields a total of17 Cepheids in common with both photometry data sets, with periodsranging between 10 and 50 days. Of these, 14 Cepheids with high-qualitylight curves are used to fit the V and I period-luminosity relations andderive apparent distance moduli, assuming a Large Magellanic Clouddistance modulus μLMC=18.50+/-0.10 mag and color excessE(B-V)=0.10 mag. Assuming A(V)/E(V-I)=2.45, the DoPHOT data yield a truedistance modulus to NGC 1326A ofμ0=31.36+/-0.17(random)+/-0.13(systematic) mag,corresponding to a distance of 18.7+/-1.5(random)+/-1.2(systematic) Mpc.The derived distance to NGC 1326A is in good agreement with the distancederived previously to NGC 1365, another spiral galaxy member of theFornax Cluster. However, the distances to both galaxies aresignificantly lower than that to NGC 1425, a third Cepheid calibrator inthe outer parts of the cluster.
| 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 HI survey for protogalaxies in the Centaurus and Fornax galaxy clusters
The results of 21-cm neutral hydrogen survey observations, made usingthe 64-m Parkes telescope, are presented for two 8 deg by 8 deg fields,centred on the Centaurus and Fornax galaxy clusters, and a smaller 1deg.5 field in Eridanus. The purpose of the observations was to searchfor extended Hi clouds with no clear optical counterparts. 31 previouslycatalogued galaxies were detected, with Hi parameters for 16 beinglisted for the first time. One previously uncatalogued dwarf galaxy(`Wombat I', J0341-3851) was found near the Fornax cluster. AustraliaTelescope Compact Array observations give an Hi mass of 8x10^7 Msolarand a diameter of 4kpc for this object, which is also visible on UKSTsurvey plates. However, no clouds with optically invisible counterpartswere detected. We deduce a 99 per cent confidence limit on the total Hidensity of such objects in the cluster and near-cluster environment ofOmega_HI<10^-2h^-1(deltaV/100kms^-1.
| Nuclei of Nearby Disk Galaxies.I.A Hubble Space Telescope Imaging Survey
We present deconvolved images of the central regions of 20 nearby diskgalaxies, obtained with the original Planetary Camera of the HubbleSpace Telescope. The galaxies span a range in Hubble type from S0 to Sm.We have measured surface brightness profiles, and inverted these toestimate luminosity-density profiles. Surface brightness profiles in thecentral regions show a variety of forms, sometimes clearly affected byheavy dust obscuration. All galaxies in the sample earlier than type Scshow a continuing rise in surface brightness up to the resolution limitin the deconvolved images. Later types show shallower slopes, consistentwith exponential disks either continuing into the center or elseflattening in the central regions. These galaxies often, but not always,exhibit an unresolved nucleus which is likely a dense nuclear starcluster. Luminosity densities in the earlier-type galaxies reach orexceed 10^4^ L_sun_,V_ pc^-3^, and the nuclei of the later-type galaxiesoccasionally approach the same level. The dS0 galaxies in our samplehave central characteristics most closely resembling the late-typegalaxies. A comparison of the central luminosity and central surfacebrightness of our galaxies with elliptical galaxies and nucleated dwarfssupports an association of late-type disks systems and such dwarfs.
| New aperture photometry for 217 galaxies in the Virgo and Fornax clusters.
We present photo electric multi-aperture photometry in UBVRI of 171 and46 galaxies in the Virgo and Fornax clusters, respectively. Many of thegalaxies have not been observed in at least one of these passbandsbefore. We discuss the reduction and transformation into the Cousinsphotometric system as well as the extinction coefficients obtainedbetween 1990 and 1993.
| 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.
| A catalog of southern groups of galaxies
A catalog of groups of galaxies identified in the southern Galactic capis presented. This catalog was constructed utilizing the group-findingalgorithm developed by Huchra and Geller (1982) to analyze galaxysamples with well-defined selection criteria and complete velocityinformation.
| Population studies in groups and clusters of galaxies. II - A catalog of galaxies in the central 3.5 deg of the Fornax Cluster
A catalog of 2678 galaxies within an area of about 40 sq deg centered onthe Fornax Cluster has been compiled based on 26 deep large-scale platesobtained with the 2.5-m Las Campanas Observatory reflector. The catalogincludes 340 likely cluster members and 2338 likely background galaxies.Radial velocities are given for 89 of the galaxies. The spatialdistributions of various types of galaxies have been modeled as the sumof a King (1962) model cluster component superimposed on a uniformbackground. Using maximum-likelihood fits to these distributions, a coreradius of 0.7 deg is found for a King model fit to the cluster,suggesting that there are few cluster members contained in the sample ofbackground galaxies.
| Southern Galaxy Catalogue.
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