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H I Detection of Two Dwarf S0 Galaxies in Nearby Groups: ESO 384-016 and NGC 59
A H I survey of 10 dE/dS0 galaxies in the nearby Sculptor and CentaurusA groups was made using the Australia Telescope Compact Array. Theobserved galaxies have accurate distances derived by Jerjen et al. usingthe surface brightness fluctuation technique. Their absolute magnitudesare in the range -9.5>MB>-15.3. Only two of the 10galaxies were detected at our detection limit (~1.0×106Msolar for the Centaurus group and ~5.3×105Msolar for the Sculptor group): the two dS0 galaxies ESO384-016 in the Centaurus A group and NGC 59 in the Sculptor group, withH I masses of (6.0+/-0.5)×106 and(1.4+/-0.1)×107 Msolar, respectively. Thosetwo detections were confirmed using the Green Bank Telescope. Thesesmall H I reservoirs could fuel future generations of low-level starformation and could explain the bluer colors seen at the center of thedetected galaxies. Similar to what is seen with the Virgo dwarfellipticalss, the two objects with H I appear to be on the outskirts ofthe groups.
| Photometric survey of the polar ring galaxy NGC 6822
Context: .We have previously established, from a carbon star survey,that the Local Group dwarf irregular galaxy NGC 6822 is much larger thanits central bright core. Aims: . Four MegaCam fields are acquiredto survey a 2°× 2° area centred on NGC 6822 to fullydetermine its extent and map its stellar populations. Methods:.Photometry of over one million stars is obtained in the SDSS g', r', i'to three magnitudes below the TRGB. RGB stars, selected from theirmagnitudes and colours, are used to map the NGC 6822 stellardistribution up to a distance of 60 arcmin. Results: .We map thereddening over the whole area. We establish that the stellar outerstructure of NGC 6822 is elliptical in shape, with ɛ=0.36 and amajor-axis PA = 65°, contrasting with the orientation of the HIdisk. The density enhancement can be seen up to a semi-major axis of 36'making NGC 6822 as big as the Small Magellanic Cloud. We fit twoexponentials to the surface density profile of the spheroid, andidentify a bulge with a scale length of 3.85' and an outer spheroid witha scale length of 10.0'. We find intermediate-age C stars up to 40'while demonstrating that the SDSS filters are unsuitable to identifyextragalactic C stars. Conclusions: .NGC 6822 is a unique LocalGroup galaxy with shape and structure suggesting a polar ringconfiguration. Radial velocities of carbon stars have indeeddemonstrated that there are two kinematical systems in NGC 6822.
| Detection of Neutral Hydrogen in Early-Type Dwarf Galaxies of the Sculptor Group
We present results of deep 21 cm neutral hydrogen (H I) lineobservations of five early- and mixed-type dwarf galaxies in the nearbySculptor group using the Australia Telescope National Facility 64 mParkes Radio Telescope. Four of these objects, ESO 294-G010, 410-G005,540-G030, and 540-G032, were detected in H I with neutral hydrogenmasses in the range (2-9)×105 Msolar(MHI/LB=0.08, 0.13, 0.16, and 0.18Msolar L-1solar, respectively). These HI masses are consistent with the gas mass expected from stellar outflowsover a large period of time. Higher spatial resolution H I data from theAustralia Telescope Compact Array interferometer were further analyzedto measure more accurate positions and the distribution of the H I gas.In the cases of the dwarfs ESO 294-G010 and ESO 540-G030, we findsignificant offsets of 290 and 460 pc, respectively, between theposition of the H I peak flux and the center of the stellar component.These offsets are likely to have internal causes such as the winds fromstar-forming regions. The fifth object, the spatially isolated dwarfelliptical galaxy Scl-dE1, remains undetected at our 3 σ limit of22.5 mJy km s-1 and thus must contain less than105 Msolar of neutral hydrogen. This leavesScl-dE1 as the only Sculptor group galaxy known in which no interstellarmedium has been found to date. The object joins a list of similarsystems, including the Local Group dwarfs Tucana and Cetus, that do notfit into the global picture of the morphology-density relation in whichgas-rich dwarf irregular galaxies are in relative isolation andgas-deficient dwarf elliptical galaxies are satellites of more luminousgalaxies.
| The Local Group and Other Neighboring Galaxy Groups
Over the last few years, rapid progress has been made in distancemeasurements for nearby galaxies based on the magnitude of stars on thetip of the red giant branch. Current CCD surveys with the Hubble SpaceTelescope (HST) and large ground-based telescopes bring ~10% accuratedistances for roughly a hundred galaxies within 5 Mpc. The new data ondistances to galaxies situated in (and around) the nearest groups-theLocal Group, M81 Group, Cen A/M83 Group, IC 342/Maffei Group, Sculptorfilament, and Canes Venatici cloud-allowed us to determine their totalmass from the radius of the zero-velocity surface, R0, whichseparates a group as bound against the homogeneous cosmic expansion. Thevalues of R0 for the virialized groups turn out to be closeeach other, in the range of 0.9-1.3 Mpc. As a result, the total massesof the groups are close to each other, as well, yielding total mass toblue luminosity ratios of 10-40 MsolarL-1solar. The new total mass estimates are 3-5times lower than old virial mass estimates of these groups. Becauseabout half of galaxies in the Local volume belong to such loose groups,the revision of the amount of dark matter (DM) leads to a low localdensity of matter, Ωm~=0.04, which is comparable withthe global baryonic fraction Ωb but much lower than theglobal density of matter, Ωm=0.27. To remove thediscrepancy between the global and local quantities ofΩm, we assume the existence of two different DMcomponents: (1) compact dark halos around individual galaxies and (2) anonbaryonic dark matter ``ocean'' with ΩDM1~=0.07 andΩDM2~=0.20, respectively.Based in part on observations made 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.
| The H I content of the recently discovered field dwarf galaxy APPLES 1
We present observations in a search for neutral hydrogen associated withthe recently detected field dwarf galaxy APPLES 1,performed with the Parkes radiotelescope. The observed radio spectrumshows no evident (>3σ rms) line emission indicating an upperlimit for the H i content of the galaxy of ~106Mȯ and providing an upper value for theMHI/LB ratio equal to 2.4 /. The low value of theH i content suggested by the observations, together with the galaxyoptical morphology, might indicate that APPLES 1 is adwarf spheroidal. This indication is in contrast with the evidence ofrecent star formation, which is typical for dwarf irregular galaxies.This may suggest that APPLES 1 belongs to the classof mixed dwarf irregular/spheroidal transition-type galaxies. We alsoconclude that the relatively low neutral gas mass in APPLES1 can be explained by an extended and inefficient starformation process, without the need for a dramatic event such asenhanced star formation or a past encounter with a massive galaxy orgalaxy group.
| A Catalog of Neighboring Galaxies
We present an all-sky catalog of 451 nearby galaxies, each having anindividual distance estimate D<~10 Mpc or a radial velocityVLG<550 km s-1. The catalog contains data onbasic optical and H I properties of the galaxies, in particular, theirdiameters, absolute magnitudes, morphological types, circumnuclearregion types, optical and H I surface brightnesses, rotationalvelocities, and indicative mass-to-luminosity and H I mass-to-luminosityratios, as well as a so-called tidal index, which quantifies the galaxyenvironment. We expect the catalog completeness to be roughly 70%-80%within 8 Mpc. About 85% of the Local Volume population are dwarf (dIr,dIm, and dSph) galaxies with MB>-17.0, which contributeabout 4% to the local luminosity density, and roughly 10%-15% to thelocal H I mass density. The H I mass-to-luminosity and the H Imass-to-total (indicative) mass ratios increase systematically fromgiant galaxies toward dwarfs, reaching maximum values about 5 in solarunits for the most tiny objects. For the Local Volume disklike galaxies,their H I masses and angular momentum follow Zasov's linear relation,expected for rotating gaseous disks being near the threshold ofgravitational instability, favorable for active star formation. We foundthat the mean local luminosity density exceeds 1.7-2.0 times the globaldensity, in spite of the presence of the Tully void and the absence ofrich clusters in the Local Volume. The mean local H I density is 1.4times its ``global'' value derived from the H I Parkes Sky Survey.However, the mean local baryon densityΩb(<8Mpc)=2.3% consists of only a half of the globalbaryon density, Ωb=(4.7+/-0.6)% (Spergel et al.,published in 2003). The mean-square pairwise difference of radialvelocities is about 100 km s-1 for spatial separations within1 Mpc, increasing to ~300 km s-1 on a scale of ~3 Mpc. alsoWe calculated the integral area of the sky occupied by the neighboringgalaxies. Assuming the H I size of spiral and irregular galaxies to be2.5 times their standard optical diameter and ignoring any evolutioneffect, we obtain the expected number of the line-of-sight intersectionswith the H I galaxy images to be dn/dz~0.4, which does not contradictthe observed number of absorptions in QSO spectra.
| The Kinematic State of the Local Volume
The kinematics of galaxies within 10 Mpc of the Milky Way isinvestigated using published distances and radial velocities. Withrespect to the average Hubble flow (isotropic or simple anisotropic),there is no systematic relation between peculiar velocity dispersion andabsolute magnitude over a range of 10 mag; neither is there any apparentvariation with galaxy type or between field and cluster members. Thereare several possible explanations for the lack of variation, though allhave difficulties: either there is no relationship between light andmass on these scales, the peculiar velocities are not produced bygravitational interaction, or the background dynamical picture is wrongin some systematic way. The extremely cold local flow of 40-60 kms-1 dispersion reported by some authors is shown to be anartifact of sparse data, a velocity dispersion of over 100 kms-1 being closer to the actual value. Galaxies with a high(positive) radial velocity have been selected against in studies of thisvolume, biasing numerical results.
| The Magellanic Stream, High-Velocity Clouds, and the Sculptor Group
The Magellanic Stream is a 100deg×10degfilament of gas that lies within the Galactic halo and contains~2×108 Msolar of neutral hydrogen. In thispaper we present data from the H I Parkes All Sky Survey (HIPASS) in thefirst complete survey of the entire Magellanic Stream and itssurroundings. We also present a summary of the reprocessing techniquesused to recover large-scale structure in the Stream. The substantialimprovement in spatial resolution and angular coverage compared toprevious surveys reveals a variety of prominent features, includingbifurcation along the main Stream filament; dense, isolated clouds thatfollow the entire length of the Stream; head-tail structures; and acomplex filamentary web at the head of the Stream where gas is beingfreshly stripped away from the Small Magellanic Cloud and the Bridge.Debris that appears to be of Magellanic origin extends out to 20°from the main Stream filaments. The Magellanic Stream has a velocitygradient of 700 km s-1 from the Clouds to the tail of theStream, ~390 km s-1 greater than that due to Galacticrotation alone, therefore implying a noncircular orbit. The dualfilaments comprising the Stream are likely to be relics from gasstripped separately from the Magellanic Bridge and the SMC. This impliesthat (1) the Bridge is somewhat older than conventionally assumed; and(2) the Clouds have been bound together for at least one or two orbits.The transverse velocity gradient of the Stream also appears to supportlong-term binary motion of the Clouds. A significant number of the mostelongated cataloged Stream clouds (containing ~1% of the Stream mass)have position angles aligned along the Stream. This suggests thepresence of shearing motions within the Stream, arising from tidalforces or interaction with the tenuous Galactic halo. As previouslynoted, clouds within one region of the Stream, along the sight line tothe less distant half (southern half on the sky) of the Sculptor Group,show anomalous properties. There are more clouds along this sight linethan any other part of the Stream, and their velocity distributionsignificantly deviates from the gradient along the Stream. We argue thatthis deviation could be due to a combination of halo material, and notto distant Sculptor clouds, based on a spatial and kinematic comparisonbetween the Sculptor Group galaxies and the anomalous clouds and thelack of cloud detection in the northern half of the group. This resulthas significant implications for the hypothesis that there might existdistant, massive high-velocity clouds within the Local Group. Catalogedclouds within the Magellanic Stream do not have a preferred scale size.Their mass spectrum f(MHI)~M-2.0HI andcolumn density spectrum f(NHI)~N-2.8HIare steep compared with Lyα absorbers and galaxies, and similar tothe anomalous clouds along the Sculptor Group sight line.
| 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.
| Star Formation in Sculptor Group Dwarf Irregular Galaxies and the Nature of ``Transition'' Galaxies
We present new Hα narrowband imaging of the H II regions in eightSculptor group dwarf irregular (dI) galaxies. The Hα luminositiesof the detected H II regions range from some of the faintest detected inextragalactic H II regions (~1035 ergs s-1 in SC24) to some of the most luminous (~1040 ergs s-1in NGC 625). The total Hα luminosities are converted into currentstar formation rates (SFRs). Comparing the Sculptor group dI's to theLocal Group dI's, we find that the Sculptor group dI's have, on average,lower values of SFR when normalized to either galaxy luminosity or gasmass (although there is considerable overlap between the two samples).The range for both the Sculptor group and Local Group samples is largewhen compared with that seen for the sample of gas-rich, quiescent, lowsurface brightness (LSB) dI's from van Zee et al. (published in 1997)and the sample of isolated dI's from van Zee (from 2000 and 2001). Thisis probably best understood as a selection effect since the nearby groupsamples have a much larger fraction of extremely low luminosity galaxiesand the smaller galaxies are much more liable to large relativevariations in current SFRs. The Sculptor group and LSB samples are verysimilar with regard to mean values of both τgas andτform, and the Local Group and isolated dI samples arealso similar to each other in these two quantities. Currently, theSculptor group lacks dI galaxies with elevated normalized current SFRsas high as the Local Group dI's IC 10 and GR 8. The properties of``transition'' (dSph/dIrr) galaxies in Sculptor and the Local Group arealso compared and found to be similar. The transition galaxies aretypically among the lowest luminosities of the gas-rich dwarf galaxies.Relative to the dwarf irregular galaxies, the transition galaxies arefound preferentially nearer to spiral galaxies and are found nearer tothe center of the mass distribution in the local cloud. While most ofthese systems are consistent with normal dI galaxies, exhibitingtemporarily interrupted star formation, the observed density-morphologyrelationship (which is weaker than that observed for the dwarfspheroidal galaxies) indicates that environmental processes such as``tidal stirring'' may play a role in causing their lower SFRs.
| Distances to nearby galaxies in Sculptor
We present an analysis of Hubble Space Telescope/WFPC2 images of ninenearby galaxies in Sculptor. We derive their distances from theluminosity of the tip of the red giant branch stars with a typicalaccuracy of ~ 12%. Their distances are 4.21 Mpc (Sc 22), 4.92 Mpc (DDO226), 3.94 Mpc (NGC 253), 3.40 Mpc (KDG 2), 3.34 Mpc (DDO 6), 3.42 Mpc(ESO 540-030), 4.43 Mpc (ESO 245-05), 4.27 Mpc (UGCA 442), and 3.91 Mpc(NGC 7793). The galaxies are concentrated in several spatially separatedloose groups around NGC 300, NGC 253, and NGC 7793. The Sculptor galaxycomplex together with the CVn I cloud and the Local Group form a 10 Mpcfilament, apparently driven by the free Hubble flow.Based on observations made with the NASA/ESA Hubble Space Telescope. TheSpace Telescope Science Institute is operated by the Association ofUniversities for Research in Astronomy, Inc. under NASA contract NAS5-26555.
| Local galaxy flows within 5 Mpc
We present Hubble Space Telescope/WFPC2 images of sixteen dwarf galaxiesas part of our snapshot survey of nearby galaxy candidates. We derivetheir distances from the luminosity of the tip of the red giant branchstars with a typical accuracy of ~ 12%. The resulting distances are4.26 Mpc (KKH 5), 4.74 Mpc (KK 16), 4.72 Mpc (KK 17), 4.66 Mpc (ESO115-021), 4.43 Mpc (KKH 18), 3.98 Mpc (KK 27), 4.61 Mpc (KKH 34), 4.99Mpc (KK 54), 4.23 Mpc (ESO 490-017), 4.90 Mpc (FG 202), 5.22 Mpc (UGC3755), 5.18 Mpc (UGC 3974), 4.51 Mpc (KK 65), 5.49 Mpc (UGC 4115), 3.78Mpc (NGC 2915), and 5.27 Mpc (NGC 6503). Based on distances and radialvelocities of 156 nearby galaxies, we plot the local velocity-distancerelation, which has a slope of H0 = 73 km s-1Mpc-1 and a radial velocity dispersion of 85 kms-1. When members of the M81 and Cen A groups are removed,and distance errors are taken into account, the radial velocitydispersion drops to sigmav = 41 km s-1. The localHubble flow within 5 Mpc exhibits a significant anisotropy, with twoinfall peculiar velocity regions directed towards the Supergalacticpoles. However, two observed regions of outflow peculiar velocity,situated on the Supergalactic equator, are far away ( ~ 50degr ) fromthe Virgo/anti-Virgo direction, which disagrees with a sphericallysymmetric Virgo-centric flow. About 63% of galaxies within 5 Mpc belongto known compact and loose groups. Apart from them, we found six newprobable groups, consisting entirely of dwarf galaxies.Based on observations made with the NASA/ESA Hubble Space Telescope. TheSpace Telescope Science Institute is operated by the Association ofUniversities for Research in Astronomy, Inc. under NASA contract NAS5-26555.}\fnmsep\thanks{Table 2, and Figs. 1 and 2, are only availablein electronic form at http://www.edpsciences.org
| Local Field of Galaxy Velocities
A sample of 145 galaxies having radial velocities relative to thecentroid of the Local Group V LG D H ij , with principal values of81:62:48 in km/sec·Mpc, which have a standard error of 4km/sec·Mpc. The minor axis of the Hubble ellipsoid is orientedalmost along the polar axis of the Local Supercluster, while the majoraxis forms an angle = (29 ± 5)° with the direction toward thecenter of the Virgo Cluster. Such a configuration of thepeculiar-velocity field shows unsatisfactory agreement with the model ofa spherically symmetric flow of galaxies toward the Virgo Cluster.Rotation of the Local Supercluster may be one reason for thisdifference. The peculiar velocities of galaxies within a volume with D V= 74 km/sec, a considerable part of which is due to the virial motionsof galaxies in groups and to distance errors. For field galaxies,located in a layer of 1 < D < 3 Mpc around the Local Group, theradial-velocity dispersion does not exceed 25 km/sec. Thevelocitydistance relation, constructed from the 20 closestgalaxies around the Local Group with D < 3 Mpc and with errorsσ(D) < 0.2 Mpc, exhibits the expected effect of gravitationaldeceleration. Using the estimate of R 0 = (0.96 ± 0.05) Mpc forthe observed radius of the zero-velocity sphere, we determined the totalmass of the Local Group to be (1.2 ± 0.2)·1012 M ȯ,which agrees well with the sum of the virial masses of the subgroups ofgalaxies around the Local Group and M31. The ratio of the Local Group'stotal mass (within R 0) to its luminosity is M/L = (23 ± 4) Mȯ/L ȯ, which does not require the existence of supermassivedark halos around our Galaxy and M31.
| Tip of the red giant branch distance for the Sculptor group dwarf ESO 540-032
We present the first VI CCD photometry for the Sculptor group galaxy ESO540-032 obtained at the Very Large Telescope UT1+FORS1. The (I, V-I)colour-magnitude diagram indicates that this intermediate-type dwarfgalaxy is dominated by old, metal-poor ([Fe/H]~ -1.7 dex) stars, with asmall population of slightly more metal-rich ([Fe/H]~ -1.3 dex), young(age 150-500 Myr) stars. A discontinuity in the I-band luminosityfunction is detected at I0 = 23.44+/- 0.09 mag. Interpretingthis feature as the tip of the red giant branch and adoptingMI = -4.20+/- 0.10 mag for its absolute magnitude, we havedetermined a Population II distance modulus of (m - M)0 =27.64 +/- 0.14 mag (3.4 +/- 0.2 Mpc). This distance confirms ESO 540-032as a member of the nearby Sculptor group but is significantly largerthan a previously reported value based on the Surface BrightnessFluctuation (SBF) method. The results from stellar population synthesismodels suggest that the application of the SBF technique on dwarfgalaxies with mixed morphology requires a detailed knowledge of theunderlying stellar composition and thus offers no advantage over adirect distance measurement using the tip of the red giant branch asdistance indicator. We produce the surface brightness profiles for ESO540-032 and derive the photometric and structural parameters. The globalproperties follow closely the relations between metallicity and bothabsolute magnitude and central surface brightness defined by dwarfelliptical galaxies in the Local Group. Finally, we identify and discussa non-stellar object near the galaxy center which may resemble aglobular cluster. Based on observations collected at the EuropeanSouthern Observatory (ESO 64.N-0069).
| 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.
| Surface BR Photometry of Newly Discovered Dwarf Elliptical Galaxies in the Nearby Sculptor and Centaurus A Groups
Prompted by the recent finding of a large number of gas-rich dwarfirregular galaxies in the nearby southern galaxy groups Sculptor (Scl)and Centaurus A (Cen A) we carried out a complementary survey to searchfor members of the gas-poor dwarf elliptical (dE) galaxy family. Intotal 18 dE candidates were identified on SRC Sky Survey films coveringthe group regions. For five dE's in the Scl group and five in the Cen Agroup, membership information is available from surface brightnessfluctuations distance measurements; two dEs in each group also haveindependent redshift measurements. The remaining eight galaxies havebeen associated to the groups based on their morphology. We acquireddeep B- and R-band CCD images for all galaxies and determined theirphotometric and structural parameters. According to the magnitude rangecovered, -14
| 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
| HI observations of nearby galaxies . I. The first list of the Karachentsev catalog
We present HI observations of the galaxies in the first list of theKarachentsev catalog of previously unknown nearby dwarf galaxies(Karachentseva & Karachentsev 1998). This survey covers all knownnearby galaxy groups within the Local Volume (i.e. within 10 Mpc) andtheir environment, that is about 25% of the total sky. A total of 257galaxies have been observed with a detection rate of 60%. We searched afrequency band corresponding to heliocentric radial velocities from -470km s-1 to ~ +4000 km s-1. Non-detections areeither due to limited coverage in radial velocity, confusion with LocalHI (mainly in the velocity range -140 km s-1 to +20 kms-1), or lack of sensitivity for very weak emission. 25% ofthe detected galaxies are located within the Local Volume. Thosegalaxies are dwarf galaxies judged by their optical linear diameter (1.4+/- 0.2 kpc on the average), their mean total HI mass (4.6107 Msun), and their observed linewidths (39 kms-1).
| Search for HI in dwarf spheroidal galaxies
After reviewing the HI content and distribution in extreme dwarfirregular (dIrr) and dwarf elliptical (dE) galaxies, previous searchesfor HI in dwarf spheroidal (dSph) galaxies will be discussed. I willreport on the recent detections of HI probably associated with the LocalGroup (LG) dSph Sculptor and dIrr/dSph Phoenix, obtained with the ATCA,along with a similar detection in the Centaurus Group dSph CEN- 41. Dataobtained for Sculptor, using the Parkes Multibeam system will also bepresented and the advantage of the wide field for such nearby objectswill be emphasised. Finally, the possible origin of the gas and thegeneral problem of the missing ISM in dSph galaxies will be discussed.
| HI properties of nearby galaxies from a volume-limited sample
We consider global HI and optical properties of about three hundrednearby galaxies with V_0 < 500 km s(-1) . The majority of them haveindividual photometric distance estimates. The galaxy sample parametersshow some known and some new correlations implying a meaningful dynamicexplanation: 1) In the whole range of diameters, 1 - 40 Kpc, the galaxystandard diameter and rotational velocity follows a nearly linearTully-Fisher relation, lg A25~(0.99+/-0.06)lg V_m. 2) The HImass-to-luminosity ratio and the HI mass-to-``total" mass (inside thestandard optical diameter) ratio increase systematically from giantgalaxies towards dwarfs, reaching maximum values 5 ;M_ȯ/L_ȯand 3, respectively. 3) For all the Local Volume galaxies their totalmass-to-luminosity ratio lies within a range of [0.2-16]M_ȯ/L_ȯ with a median of 3.0 ;M_ȯ/L_ȯ. TheM25/L ratio decreases slightly from giant towards dwarfgalaxies. 4) The M_HI/L and M25/L ratios for the samplegalaxies correlate with their mean optical surface brightness, which maybe caused by star formation activity in the galaxies. 5) The M_HI/L andM25/L ratios are practically independent of the local massdensity of surrounding galaxies within the range of densities of aboutsix orders of magnitude. 6) For the LV galaxies their HI mass andangular momentum follow a nearly linear relation: lgM_HI~(0.99+/-0.04)lg (V_m* A25), expected for rotatinggaseous disks being near the threshold of gravitational instability,favourable for active star formation. Table in the Appendix is availableonly in electronic form at the CDS via anonymous ftp 130.79.128.5 orhttp//cdsweb.u-strasbg.fr/Abstract.html
| Surface Brightness Fluctuation Distances to Dwarf Elliptical Galaxies in the Sculptor Group
As part of an ongoing search for dwarf elliptical galaxies (dE's) in thevicinity of the Local Group (Jerjen et al.), we acquired deep B- andR-band images for five dE candidates identified on morphologicalcriteria in the Sculptor (Scl) group region. We carried out a surfacebrightness fluctuation (SBF) analysis on the R-band images to measurethe apparent fluctuation magnitude m_R for each dE. Using predictionsfrom stellar population synthesis models (Worthey) giving M_R values inthe narrow range between -1.17 and -1.13, the galaxy distances weredetermined. All of these dE candidates turned out to be satellites ofScl group major members. A redshift measurement of the dE candidate ESO294-010 yielded an independent confirmation of its group membership: the[O III] and Hα emission lines from a small H II region gave aheliocentric velocity of 117 (+/-5) km s^-1, in close agreement with thevelocity of its parent galaxy NGC 55 (v_ȯ = 125 km s^-1). Theprecision of the SBF distances (5%-10%) contributes to delineating thecigar-like distribution of the Scl group members, which extend overdistances from 1.7 to 4.4 Mpc and are concentrated in three, possiblyfour subclumps. The Hubble diagram for nine Scl galaxies, including twoof our dE's, exhibits a tight linear velocity-distance relation with asteep slope of 119 km s^-1 Mpc^-1. The results indicate thatgravitational interaction among the Scl group members plays only a minorrole in the dynamics of the group. However, the Hubble flow of theentire system appears strongly disturbed by the large masses of ourGalaxy and M31, which leads to the observed shearing motion. From thedistances and velocities of 49 galaxies located in the Local Group andtoward the Scl group, we illustrate the continuity of the galaxydistribution, which strongly supports the view that the two groups forma single supergalactic structure.
| 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.
| A list of new nearby dwarf galaxy candidates
To increase completeness of the distance limited sample of nearbygalaxies from the \cite[Kraan-Korteweg & Tammann (1979)]{Kra79}catalogue we undertook a search for small companions of larger knowngalaxies which have corrected radial velocities within 500 km/s. Basedprimarily on the POSS-II and ESO/SERC films we found 260 nearby dwarfgalaxy candidates with angular diameters aga0 .5 arcmin. More than 50%of the objects were revealed for the first time. As we suppose, asignificant part of them (about 30%) may really belong to the LocalVolume sample. Tables 1 and 2 also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via\breakftp://cdsweb.u-strasbg.fr/Abstract.html
| Discovery of Numerous Dwarf Galaxies in the Two Nearest Groups of Galaxies.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.1313C&db_key=AST
| Total and effective colors of 501 galaxies in the Cousins VRI photometric system
Total color indices (V-R)T, (V-I)T and effectivecolor indices (V-R)e, (V-I)e in the Cousins VRIphotometric system are presented for 501 mostly normal galaxies. Thecolors are computed using a procedure outlined in the Third ReferenceCatalogue of Bright Galaxies (RC3) whereby standard color curvesapproximated by Laplace-Gauss integrals are fitted to observedphotoelectric multiaperture photometry. 11 sources of such photometrywere used for our analysis, each source being assigned an appropriateweight according to a rigorous analysis of residuals of the data fromthe best-fitting standard color curves. Together with the integrated B-Vand U-B colors provided in RC3, our analysis widens the range ofwavelength of homogeneously defined colors of normal galaxies of allHubble types. We present color-color and color-type relations that canbe modeled to understand the star formation history of galaxies.
| Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.
| The Montreal blue galaxy survey. I - First list of ultraviolet-bright candidates
The first results of a UV-bright galaxy survey using theMontreal-Cambridge-Tololo (MCT) plate collection are presented. Visualinspection of 57 CTIO Curtis Schmidt plates, cnvering more than 1300 sqdeg, has resulted in the identification of 95 UV-bright galaxiesbrighter than B = 15.5. Even though 80 percent of these objects are IRASsources, barely 20 percent have their nature already established. Theinitial result of our survey shows that the bulk of our UV-brightcandidates are narrow emission-line galaxies commonly known as starburstor H II galaxies. The fraction of AGNs found is somewhat less than 10percent, but comparable to what has been found by the Markarian survey.
| 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.
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