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The Globular Cluster System of NGC 1399. II. Kinematics of a Large Sample of Globular Clusters
We study the kinematics and dynamics of the globular cluster system ofNGC 1399, the brightest elliptical galaxy near the center of the Fornaxcluster of galaxies. The observational data consists ofmedium-resolution spectra, obtained at the Very Large Telescope withFORS2 and the Mask Exchange Unit (MXU). Our sample comprises 468 radialvelocities in the magnitude range 201.6) and blue clusters (C-R<1.6), and find velocitydispersions for these groups of 255+/-13 and 291+/-14 km s-1,respectively, again radially constant. Any possible rotation of eitherof these cluster populations is below the detection limit, with theexception of a weak signature of rotation for the blue clusters moredistant than 6'. Spherical models point to a circular velocity of419+/-30 km s-1, assuming isotropy for the red clusters. Thisvalue is constant out to 40 kpc. The inferred dark halo potential can bewell represented by a logarithmic potential. A halo of the NFW type alsoprovides a good fit to the observations. The orbital structure of theclusters can only be weakly constrained. It is consistent with isotropyfor the red clusters and a slight tangential bias for the blue clusters.Some mass profiles derived from X-ray analyses do not agree with aconstant circular velocity within our radial range, irrespective of itsexact value. Interpreting the extreme low radial velocities as spacevelocities of bound clusters near their pericentric distances wouldrequire an extension of the cluster system of at least 200 kpc.Implications for formation scenarios of the cluster system are brieflycommented on.Based on observations collected at the European Southern Observatory,Cerro Paranal, Chile; ESO program 66.B-0393.
| The surface brightness and colour-magnitude relations for Fornax cluster galaxies
We present BVI photometry of 190 galaxies in the central 4 ×3deg2 region of the Fornax cluster observed with the MichiganCurtis Schmidt Telescope. Results from the Fornax Cluster SpectroscopicSurvey (FCSS) and the Flair-II Fornax Surveys have been used to confirmthe membership status of galaxies in the Fornax Cluster Catalogue (FCC).In our catalogue of 213 member galaxies, 92 (43 per cent) have confirmedradial velocities.In this paper, we investigate the surface brightness-magnitude relationfor Fornax cluster galaxies. Particular attention is given to the sampleof cluster dwarfs and the newly discovered ultracompact dwarf galaxies(UCDs) from the FCSS. We examine the reliability of the surfacebrightness-magnitude relation as a method for determining clustermembership and find that at surface brightnesses fainter than 22 magarcsec-2, it fails in its ability to distinguish betweencluster members and barely resolved background galaxies. Cluster membersexhibit a strong surface brightness-magnitude relation. Both elliptical(E) galaxies and dwarf elliptical (dE) galaxies increase in surfacebrightness as luminosity decreases. The UCDs lie off the locus of therelation.B-V and V-I colours are determined for a sample of 113 cluster galaxiesand the colour-magnitude relation is explored for each morphologicaltype. The UCDs lie off the locus of the colour-magnitude relation. Theirmean V-I colours (~1.09) are similar to those of globular clustersassociated with NGC 1399. The location of the UCDs on both surfacebrightness and colour-magnitude plots supports the `galaxy threshing'model for infalling nucleated dwarf elliptical (dE, N) galaxies.
| 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.
| Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry
We present R-band CCD photometry for 1332 early-type galaxies, observedas part of the ENEAR survey of peculiar motions using early-typegalaxies in the nearby universe. Circular apertures are used to tracethe surface brightness profiles, which are then fitted by atwo-component bulge-disk model. From the fits, we obtain the structuralparameters required to estimate galaxy distances using theDn-σ and fundamental plane relations. We find thatabout 12% of the galaxies are well represented by a pure r1/4law, while 87% are best fitted by a two-component model. There are 356repeated observations of 257 galaxies obtained during different runsthat are used to derive statistical corrections and bring the data to acommon system. We also use these repeated observations to estimate ourinternal errors. The accuracy of our measurements are tested by thecomparison of 354 galaxies in common with other authors. Typical errorsin our measurements are 0.011 dex for logDn, 0.064 dex forlogre, 0.086 mag arcsec-2 for<μe>, and 0.09 for mRC,comparable to those estimated by other authors. The photometric datareported here represent one of the largest high-quality and uniformall-sky samples currently available for early-type galaxies in thenearby universe, especially suitable for peculiar motion studies.Based on observations at Cerro Tololo Inter-American Observatory (CTIO),National Optical Astronomy Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation (NSF);European Southern Observatory (ESO); Fred Lawrence Whipple Observatory(FLWO); and the MDM Observatory on Kitt Peak.
| A Hubble Space Telescope Survey of the Mid-Ultraviolet Morphology of Nearby Galaxies
We present a systematic imaging survey of 37 nearby galaxies observedwith the Hubble Space Telescope (HST) Wide Field and Planetary Camera 2(WFPC2) in the mid-UV F300W filter, centered at 2930 Å, as well asin the I-band (F814W) filter at 8230 Å. Eleven of these galaxieswere also imaged in the F255W filter, centered at 2550 Å. Oursample is carefully selected to include galaxies of sufficiently smallradius and high predicted mid-UV surface brightness to be detectablewith WFPC2 in one orbit and covers a wide range of Hubble types andinclinations. The mid-UV (2000-3200 Å) spans the gap betweenground-based UBVR(IJHK) images, which are available or were acquired forthe current study, and far-UV images available from the Astro/UITmissions for 15 galaxies in our sample. The first qualitative resultsfrom our study are as follows:1. Early-type galaxies show a significantdecrease in surface brightness going from the red to the mid-UV,reflecting the absence of a dominant young stellar population and insome cases the presence of significant (central) dust lanes. Galaxiesthat are early types in the optical show a variety of morphologies inthe mid-UV that can lead to a different morphological classification,although not necessarily as later type. Some early-type galaxies becomedominated by a blue nuclear feature or a point source in the mid-UV,e.g., as a result of the presence of a Seyfert nucleus or a LINER. Thisis in part due to our mid-UV surface brightness selection, but it alsosuggests that part of the strong apparent evolution of weak AGNs inearly-type galaxies may be due to surface brightness dimming of theirUV-faint stellar population, which renders the early-type host galaxiesinvisible at intermediate to higher redshifts.2. About half of themid-type spiral and star-forming galaxies appear as a latermorphological type in the mid-UV, as Astro/UIT also found primarily inthe far-UV. Sometimes these differences are dramatic (e.g., NGC 6782shows a spectacular ring of hot stars in the mid-UV). However, not allmid-type spiral galaxies look significantly different in the mid-UV.Their mid-UV images show a considerable range in the scale and surfacebrightness of individual star-forming regions. Almost without exception,the mid-type spirals in our sample have their small bulges bisected by adust lane, which often appears to be connected to the inner spiral armstructure.3. The majority of the heterogeneous subset of late-type,irregular, peculiar, and merging galaxies display F300W morphologiesthat are similar to those seen in F814W, but with important differencesdue to recognizable dust features absorbing the bluer light and to hotstars, star clusters, and star formation ``ridges'' that are bright inthe mid-UV. Less than one-third of the galaxies classified as late typein the optical appear sufficiently different in the mid-UV to result ina different classification.Our HST mid-UV survey of nearby galaxiesshows that, when observed in the rest-frame mid-UV, early- to mid-typegalaxies are more likely to be misclassified as later types thanlate-type galaxies are to be misclassified as earlier types. This isbecause the later type galaxies are dominated by the same young and hotstars in all filters from the mid-UV to the red and so have a smaller``morphological K-correction'' than true earlier type galaxies. Themorphological K-correction can thus explain part, but certainly not all,of the excess faint blue late-type galaxies seen in deep HST fields.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained at the Space Telescope Science Institute (STScI), which isoperated by the Association of Universities for Research in Astronomy(AURA), Inc., under NASA contract NAS 5-26555. Also based in part onobservations made with the Vatican Advanced Technology Telescope: theAlice P. Lennon Telescope and the Thomas J. Bannan AstrophysicsFacility.
| Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample
This paper presents data on the ENEARc subsample of the larger ENEARsurvey of nearby early-type galaxies. The ENEARc galaxies belong toclusters and were specifically chosen to be used for the construction ofa Dn-σ template. The ENEARc sample includes newmeasurements of spectroscopic and photometric parameters (redshift,velocity dispersion, line index Mg2, and the angular diameterdn), as well as data from the literature. New spectroscopicdata are given for 229 cluster early-type galaxies, and new photometryis presented for 348 objects. Repeat and overlap observations withexternal data sets are used to construct a final merged catalogconsisting of 640 early-type galaxies in 28 clusters. Objectivecriteria, based on catalogs of groups of galaxies derived from completeredshift surveys of the nearby universe, are used to assign galaxies toclusters. In a companion paper, these data are used to construct thetemplate Dn-σ distance relation for early-typegalaxies, which has been used to estimate galaxy distances and derivepeculiar velocities for the ENEAR all-sky sample. Based on observationsat Complejo Astronomico El Leoncito, operated under agreement betweenthe Consejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; Cerro Tololo Inter-American Observatory,National Optical Astronomical Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation; the EuropeanSouthern Observatory (ESO), partially under the ESO-ON agreement; theFred Lawrence Whipple Observatory; the Observatório do Pico dosDias, operated by the Laboratório Nacional de Astrofísicaand the MDM Observatory at Kitt Peak.
| An Ultraviolet/Optical Atlas of Bright Galaxies
We present wide-field imagery and photometry of 43 selected nearbygalaxies of all morphological types at ultraviolet and opticalwavelengths. The ultraviolet (UV) images, in two broad bands at 1500 and2500 Å, were obtained using the Ultraviolet Imaging Telescope(UIT) during the Astro-1 Spacelab mission. The UV images have ~3"resolution, and the comparison sets of ground-based CCD images (in oneor more of B, V, R, and Hα) have pixel scales and fields of viewclosely matching the UV frames. The atlas consists of multiband imagesand plots of UV/optical surface brightness and color profiles. Otherassociated parameters, such as integrated photometry and half-lightradii, are tabulated. In an appendix, we discuss the sensitivity ofdifferent wavebands to a galaxy's star formation history in the form of``history weighting functions'' and emphasize the importance of UVobservations as probes of evolution during the past 10-1000 Myr. We findthat UV galaxy morphologies are usually significantly different fromvisible band morphologies as a consequence of spatially inhomogeneousstellar populations. Differences are quite pronounced for systems in themiddle range of Hubble types, Sa through Sc, but less so for ellipticalsor late-type disks. Normal ellipticals and large spiral bulges arefainter and more compact in the UV. However, they typically exhibitsmooth UV profiles with far-UV/optical color gradients which are largerthan any at optical/IR wavelengths. The far-UV light in these cases isprobably produced by extreme horizontal branch stars and theirdescendants in the dominant, low-mass, metal-rich population. The coolstars in the large bulges of Sa and Sb spirals fade in the UV while hotOB stars in their disks brighten, such that their Hubble classificationsbecome significantly later. In the far-UV, early-type spirals oftenappear as peculiar, ringlike systems. In some spiral disks, UV-brightstructures closely outline the spiral pattern; in others, the disks canbe much more fragmented and chaotic than at optical wavelengths.Contributions by bright active galactic nuclei (AGNs) to the integratedUV light in our sample range from less than 10% to nearly 100%. A numberof systems have unusual UV-bright structures in their inner disks,including rings, compact knots, and starburst nuclei, which could easilydominate the UV light in high-redshift analogs. A significant butvariable fraction of the far-UV light in spiral disks is diffuse ratherthan closely concentrated to star-forming regions. Dust in normal spiraldisks does not control UV morphologies, even in some highly inclineddisk systems. The heaviest extinction is apparently confined to thinlayers and the immediate vicinity of young H II complexes; the UV lightemerges from thicker star distributions, regions evacuated of dust byphotodestruction or winds, or by virtue of strong dust clumpiness. Onlyin cases where the dust layers are disturbed does dust appear to be amajor factor in UV morphology. The UV-bright plume of M82 indicates thatdust scattering of UV photons can be important in some cases. In acompanion paper, we discuss far-UV data from the Astro-2 mission andoptical comparisons for another 35 galaxies, emphasizing face-onspirals.
| Ages and Metallicities of Fornax Dwarf Elliptical Galaxies
Narrowband photometry is presented on 27 dwarf ellipticals in the Fornaxcluster. Calibrated with Galactic globular cluster data andspectrophotometric population models, the colors indicated that dwarfellipticals have a mean [Fe/H] of -1.00+/-0.28 ranging from -1.6 to-0.4. The mean age of dwarf ellipticals, also determinedphotometrically, is estimated at 10+/-1 Gyr compared with 13 Gyr forbright Fornax ellipticals. Comparison of our metallicity color andMg2 indices demonstrates that the [Mg/Fe] ratio is lower indwarf ellipticals than their more massive cousins, which is consistentwith a longer duration of initial star formation to explain theiryounger ages. There is a increase in dwarf metallicity with distancefrom the Fornax cluster center, where core galaxies are on average 0.5dex more metal-poor than halo dwarfs. In addition, we find the halodwarfs are younger in mean age compared with core dwarfs. One possibleexplanation is that the intracluster medium ram pressure strips the gasfrom dwarf ellipticals, halting star formation (old age) and stoppingenrichment (low metallicity) as they enter the core.
| The Fornax spectroscopic survey. I. Survey strategy and preliminary results on the redshift distribution of a complete sample of stars and galaxies
The Fornax Spectroscopic Survey will use the Two degree Fieldspectrograph (2dF) of the Anglo-Australian Telescope to obtain spectrafor a complete sample of all 14000 objects with 16.5 <= bj<= 19.7 in a 12 square degree area centred on the Fornax Cluster. Theaims of this project include the study of dwarf galaxies in the cluster(both known low surface brightness objects and putative normal surfacebrightness dwarfs) and a comparison sample of background field galaxies.We will also measure quasars and other active galaxies, any previouslyunrecognised compact galaxies and a large sample of Galactic stars. Byselecting all objects--both stars and galaxies--independent ofmorphology, we cover a much larger range of surface brightness and scalesize than previous surveys. In this paper we first describe the designof the survey. Our targets are selected from UK Schmidt Telescope skysurvey plates digitised by the Automated Plate Measuring (APM) facility.We then describe the photometric and astrometric calibration of thesedata and show that the APM astrometry is accurate enough for use withthe 2dF. We also describe a general approach to object identificationusing cross-correlations which allows us to identify and classify bothstellar and galaxy spectra. We present results from the first 2dF field.Redshift distributions and velocity structures are shown for allobserved objects in the direction of Fornax, including Galactic stars,galaxies in and around the Fornax Cluster, and for the background galaxypopulation. The velocity data for the stars show the contributions fromthe different Galactic components, plus a small tail to high velocities.We find no galaxies in the foreground to the cluster in our 2dF field.The Fornax Cluster is clearly defined kinematically. The mean velocityfrom the 26 cluster members having reliable redshifts is 1560 +/- 80\:km\:s-1. They show a velocity dispersion of 380 +/- 50\:km\:s-1. Large-scale structure can be traced behind thecluster to a redshift beyond z=0.3. Background compact galaxies and lowsurface brightness galaxies are found to follow the general galaxydistribution.
| The Nature of Accreting Black Holes in Nearby Galaxy Nuclei
We have found compact X-ray sources in the center of 21 (54%) of 39nearby face-on spiral and elliptical galaxies with available ROSAT HRIdata. ROSAT X-ray luminosities (0.2-2.4 keV) of these compact X-raysources are ~10^37-10^40 ergs s^-1 (with a mean of 3x10^39 ergs s^-1).The mean displacement between the location of the compact X-ray sourceand the optical photometric center of the galaxy is ~390 pc. The factthat compact nuclear sources were found in nearly all (five of six)galaxies with previous evidence for a black hole or an active galacticnucleus (AGN) indicates that at least some of the X-ray sources areaccreting supermassive black holes. ASCA spectra of six of the 21galaxies show the presence of a hard component with relatively steep(Gamma~2.5) spectral slope. A multicolor disk blackbody model fits thedata from the spiral galaxies well, suggesting that the X-ray object inthese galaxies may be similar to a black hole candidate in its soft(high) state. ASCA data from the elliptical galaxies indicate that hot(kT~0.7 keV) gas dominates the emission. The fact that (for both spiraland elliptical galaxies) the spectral slope is steeper than in normaltype 1 AGNs and that relatively low absorbing columns (N_H~10^21 cm^-2)were found to the power-law component indicates that these objects aresomehow geometrically and/or physically different from AGNs in normalactive galaxies. The X-ray sources in the spiral and elliptical galaxiesmay be black hole X-ray binaries, low-luminosity AGNs, or possibly youngX-ray luminous supernovae. Assuming the sources in the spiral galaxiesare accreting black holes in their soft state, we estimate black holemasses ~10^2-10^4 M_solar.
| The central region of the Fornax cluster. II. Spectroscopy and radial velocities of member and background galaxies
Radial velocities of 94 galaxies brighter than about V_tot = 20 mag inthe direction of the central Fornax cluster have been measured. Exceptfor 8 Fornax members, all galaxies lie in the background. Among the 8members, there are 5 nucleated dwarf ellipticals that are already listedin the FCC (\cite[Ferguson 1989]{ferg89}). Two of the 3 ``new'' membersare very compact and have surface brightnesses comparable to globularclusters, however their luminosities are in the range of dwarfelliptical nuclei. The measured line indices (especially Mg2, Hβ ,and iron) of the brighter of the compact objects suggest a solarmetallicity, whereas the fainter compact object as well as the dE, Nshave line indices that are similar to those of old metal-poor globularclusters (GCs). However, with these data it is not possible to clearlyclassify the compact objects either as very bright globular clusters,isolated nuclei of dE, Ns, or even compact ellipticals. A backgroundgalaxy cluster at z = 0.11 has been found just behind the center of theFornax cluster. This explains the excess population of galaxies reportedin Paper I. The brightest galaxy of the background cluster lies only1farcm1 south of NGC 1399 and is comparable in absolute luminosity withthe central Fornax galaxy itself.Table 2 containing the position, magnitude and velocity of all galaxiesis also available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The central region of the Fornax cluster. I. A catalog and photometric properties of galaxies in selected CCD fields
We present a photometric catalog (based on V and I photometry) ofgalaxies in the central regions of the Fornax galaxy cluster. Our 11 CCDfields cover 0.17 square degrees in total. The limiting surfacebrightness is around 24 mag arcsec(-2) , similar to that of\cite[Ferguson's (1989]{ferg}) catalog, whereas our limiting totalmagnitude is around V =~ 22 mag, about two magnitudes fainter. It is thesurface brightness limit, however, that prevents us from detecting thecounterparts of the faintest Local Group dwarf spheroidals. Thephotometric properties of all objects are presented as a catalog(Appendix A). The properties and fit parameters of the surfacebrightness profiles for a sub-sample are presented as a second catalog(Appendix B)(1) . We can only add 4 new dwarf galaxies to Ferguson'scatalog. However, we confirm that the dwarf galaxies in Fornax follow asimilar surface brightness - magnitude relation as the Local Groupdwarfs. They also follow the color (metallicity) - magnitude relationseen in other galaxy clusters. A formerly suspected excess of dwarfgalaxies surrounding the central giant cD galaxy NGC 1399 can finally beruled out. An enhanced density of objects around NGC 1399 can indeed beseen, but it appears displaced with respect to the central galaxy and isidentified as a background cluster at z=0.11 in Paper II of theseseries, which will discuss spectroscopic results for our sample. Thetables of Appendix A and Appendix B are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http://cdsweb.u-strasbg.fr/Abstract.html.
| 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.
| Deep UV Imaging of Galaxies in the Fornax Cluster
We compare the Astro-1 Ultraviolet Imaging Telescope (UIT) deep image ofthe Fornax cluster with deep optical surveys for purposes of determiningthe efficacy of vacuum ultraviolet imaging in terms of the recovery ofvery faint and/or diffuse galaxies. This field covers approximately 1/3of a square degree and contains 15 galaxies with B_t_ brighter than 18.0mag. A 1000 s near-UV image detected ten of these galaxies. These tendetections include three luminous ellipticals, two bonafide dwarfellipticals, and five galaxies of small angular size that may or may notbe members of the Fornax cluster. If these optically faint galaxies aremembers of the Fornax cluster, then the VUV imaging did sample anappreciable range in the galaxy luminosity function. For the dwarfellipticals, a comparison of their optical and UV fluxes indicates theUV light is not dominated by any hot population but rather representsthe general UV characteristics of the underlying stellar population. Inparticular, we can place an upper limit of 25 O3-5 stars that arepresent due to possible low level star formation. Furthermore, theUV-optical colors of the dEs are significantly redder than Galacticglobular clusters which indicates that these dEs do not have asignificant population of extreme horizontal branch stars. With thefailure of the near-UV camera aboard the Astro-2 mission, theopportunity for performing a deeper near-UV survey has been lost. Weconclude, however, that such a survey would have good sensitivity to thedetection of optically faint and/or diffuse galaxies and would providecredible information on the galaxy luminosity function.
| 'Global mapping' B-band photometry of a complete sample of Fornax and Virgo early-type galaxies
We present the B-band surface photometry of 19 early-type galaxies ofthe Virgo cluster, and of 28 galaxies of the same morphological typebelonging to the Fornax clusters, obtained through the `global mapping'technique which couples CCD and photographic plates. Taking into account33 galaxies already studied by Caon et al. (1990) with the samemethodology, the Virgo sample of early-type galaxies is now 80% completedown to B_T_=14. The Fornax sample is 95% complete down to B_T_=15. Thegeometric and photometric properties of the total sample of 80 galaxiesare derived measuring accurate light profiles, ellipticities, positionangles and Fourier coefficients of the isophotes. The main sources oferrors of the `global mapping' procedure are reviewed and the effects ofseeing discussed. Global galaxian parameters such as total luminosity,effective radius, and effective surface brightness, are computed for thewhole sample in a homogeneous way. Our goal is to create an unbiased setof data to be used for investigating the process of galaxy formation andevolution.
| 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.
| The surface brightness test for the expansion of the universe. II - Radii, surface brightness, and absolute magnitude correlations for nearby E galaxies
Data for elliptical galaxies in the Virgo, Fornax, and Coma clusters andin the general field are analyzed in order to determine the dispersionin average surface brightness. The data are discussed using measures ofboth the effective radius and the Petrosian r(eta) radii. The dispersionis found to be about 0.5 mag after reducing the data to absolutemagnitude M(B) = -22. This value is smaller than the 1.8 mag Tolman (1 +z) exp 4 factor, even at the modest redshift of z = 0.5, showing thatthe Tolman test is feasible in practice as well as in principle.
| Revised coordinates for 373 selected objects in the Southern Galaxy Catalogue
Improved positions have been determined for 373 galaxies listed in theSouthern Galaxy Catalogue of Corwin et al. (1985) as having poorcoordinates. The revised coordinates are expected to be good to 6 arcsec(rms) in each coordinate.
| 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.
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