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An unbiased deep search for small-area molecular structures
Context: .Small-area molecular structures (SAMS) resembling clumpusculesproposed as candidates for baryonic dark matter, have been detected inan area where the shielding is too low for them to survive for a longtime. Aims: .I present the results of an unbiased deep search formolecular clumpuscules to study the frequency of occurence of suchstructures km s-1. Methods: .The area surroundingthese structures has been surveyed using the FCRAO 14m telescope in theCO (1to0) transition. The field covered is 20' by 20'. The resulting rmsof the data is only 0.04 K in a 0.127 wide channel. Additionally,high-angular resolution observations of the 13CO andC18O (J=1to0) transitions were obtained with the IRAMPlateau-de-Bure Interferometer. Results: .3 new SAMS have beendetected. The structures have very low intensities which makes itimpossible to detect them in large scale CO surveys conducted to map themolecular gas of the Milky Way. Their radial velocity is similar to thatof the surrounding HI gas. The clouds follow the same size-linewidthrelation as found for giant molecular clouds or Galactic cirrus clouds.The observations clearly show that most of the large linewidths observedat low angular resolution are caused by a large velocity differencebetween the clumps seen at highest angular resolution. The non-detectionof the structures in the high-angular resolution observations of the13CO and C18O (J=1to0) transitions shows that the12CO (J=1to0) transition must have a low optical depth. At anadopted distance of 100 pc the structures have masses of only Jupitermass or below. Conclusions: .The new observations show that SAMSmight be an abundant phenomenon in the interstellar medium but notrecognized as such due to their small size. If they are made of ordinaryinterstellar matter with solar metallicity they likely contribute onlylittle to the total interstellar mass.
| A Tiny Galactic Dust Cloud Projected onto NGC 3269?
We report on new observations obtained with the Magellan Clay telescopeof a tiny dust patch in the Sa galaxy NGC 3269, in the Antlia galaxycluster. It has already been suspected to be a projected Galacticforeground cloud. In this case, a size of about 4" and a maximumabsorption of ~1 mag in the B band would make it unique so far. Wepresent further evidence for its Galactic nature from imaging underexcellent seeing conditions (0.3"-0.6"). This dust cloud could be thefirst optically identified counterpart of a new type of molecular cloudrecently discovered by Heithausen.
| The globular cluster systems of NGC 3258 and NGC 3268 in the Antlia cluster
The Antlia galaxy cluster is the third nearest galaxy cluster afterVirgo and Fornax. We used the wide-field MOSAIC camera of the 4-m CTIOtelescope to search in the brightest cluster galaxies for globularcluster systems, which were detected in the two larger ellipticals - NGC3258 and NGC 3268. These galaxies each contain several thousandclusters; NGC 3258 more than NGC 3268. The color distributions of theglobular cluster systems are clearly bimodal. The peak colors agree withthose of other ellipticals. The radial number density profiles of theglobular cluster systems are indistinguishable for the two galaxies andno difference in the distribution of red and blue clusters - as observedin other elliptical galaxies - can be seen. The light profile of NGC3268 appears to be similar to that of NGC 1399, the central galaxy ofthe Fornax cluster. NGC 3258 has a light profile which is steeper atlarge radii. Both galaxies exhibit color gradients, becoming blueroutwards. In NGC 3268, the color and morphology in the inner 3 arcsecindicate the presence of an inner dusty disk. The globular clustersystems closely trace the galaxy light in the studied radial regime. Theelongation of the cluster systems of both galaxies is approximatelyaligned at large radii with the connecting axis of the two galaxies. Wefind specific frequencies within a radial range of 4 arcmin ofSN=3.0+/-2.0 for NGC 3268 and SN=6.0+/-2.5 for NGC3258.As a byproduct resulting from surveying our wide-field frames, wedescribe a strange absorption feature in the Antlia spiral galaxy NGC3269, which we argue might be a tiny galactic dust cloud projected ontoNGC 3269.Based on observations collected at the Cerro Tololo Inter-AmericanObservatory (CTIO).
| A study of neutral hydrogen in five small galaxy groups
High-resolution Hi imaging observations of a heterogeneous sample ofsmall galaxy groups are presented. The five galaxy groups studied show abroad range of individual Hi properties: e.g. loose groups surroundingLGG 138 and the genuinely compact LGG 455 are identified; a massive ringof neutral gas is discovered encircling two luminous galaxies in the LGG138 group; a galaxy-sized mass of Hi is found in LGG 455 confined to anextragalactic cloud which exceeds the threshold density for starformation, yet is optically invisible; and the CCG 1 group is argued tobe a chance alignment of Centaurus cluster galaxies. Global results ofthe study are that the deficit of Hi flux in synthesis imaging datacompared with single-dish data is put forward as a quantitative measureof the diffuseness of neutral gas in galaxy groups; several groupscontain gas-poor galaxies that ordinarily would contain detectablequantities of Hi - this is interpreted as being caused by an increasedchance of gas-sweeping collisions in the group environment; and someevidence is found to support previous findings that compact groupspreferentially occur in loose systems.
| ASCA Observations of a Near-by Cluster in Antlia
The Antlia cluster is a near-by poor cluster which has a redshift of z =0.0087. X-ray observations with ASCA have revealed that the cluster isalmost isothermal in the X-ray with a temperature of kT ~ 2.0 keV. Themetal abundance is Z ~ 0.35\ ZSolar , and the 0.5-10.0 keVcluster luminosity is ~ 3.4 x 1042\h75-2 erg s-1 within r < 250\h-175 kpc. There was no X-ray central excessbrightness and little central cool component, which are frequently seenin near-by poor clusters. The Antlia cluster is the nearest poor clusterwithout these central features.
| 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
| 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.
| The Catalog of Southern Ringed Galaxies
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
| Compact groups of galaxies in the nearby universe
We have searched for compact groups of galaxies among the largestcatalog of nearby groups (LGG catalog). 21 new compact groups of atleast 3 members were found. Their surface brightnesses are generallylower than those of Hickson compact groups (HCGs), and theircharacteristics are close to those of loose groups. We have alsoretrieved all HCGs of the nearby universe. These are all embedded ingroups, forming the cores or substructures of loose groups. Theseresults suggest that compact groups may form as core or substructureswithin loose groups (like the HCGs), or form from loose groups when theystart collapsing (like those of the LGG).
| 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.
| Integrated photometric properties of early type ringed galaxies
In order to elucidate the structure and evolution of barred and ovalgalaxies, over 300 of the more than 1000 galaxies in the current versionof the Catalog of Southern ringed Galaxies are subclassified intoring/pseudoring categories. Photoelectric multicolor photometry of 29ringed galaxies showing outer rings and pseudorings of the suspectedouter Lindblad resonance types reveals nothing unusual about the globalstar formation rates. The galaxies have relatively normal colors fortheir type but slightly lower than average surface brightnesses. It isdemonstrated that integrated colors (V-R)T and(V-I)T can be derived reasonably well by using standard RC2color curves originally designed for (B-V)T and(U-B)T determinations. A comparison between the presentintegrated photoelectric parameters and those in the ESO-LV data basereveals good agreement on B-band magnitudes but not total R-bandmagnitudes or B-R colors.
| Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
| The outer Lindblad resonance and the morphology of early type disk galaxies
CCD images and color index maps of 22 galaxies from the Catalog ofSouthern Ringed Galaxies (CSRG) are used to examine distinct categoriesof the morphology of outer rings and pseudorings in SB and SAB galaxies,which bear a remarkable resemblance to the gaseous rings which developednear the outer Lindblad resonance in n-body models of barred spirals. Ina class of rings where the arms wind about 180 deg with respect to theends of a bar or oval, nine out of 11 examples display blue nuclei orcircumnuclear rings in a B-I color index map. This contrasts with aclass where the arms wind about 270 deg with respect to the ends of abar or oval, for which only 3 out of 11 examples display nuclear starformation. A similar correlation regarding the presence or absence of aclear dust lane pattern is found within the region of a bar or inneroval. Images of eight additional CSRG galaxies which displaymorphological details of special interest are presented.
| Population studies in groups and clusters of galaxies. III - A catalog of galaxies in five nearby groups
Five nearby groups of galaxies have been surveyed using large-scaleplates from the 2.5 m duPont Telescope at Las Campanas Observatory.Catalogs of galaxies brighter than B(T) = 20 are presented for the Leo,Dorado, NGC 1400, NGC 5044, and Antlia groups. A total of 1044 galaxiesare included, from visual inspection of 14 plates, covering 31 degsquare. Galaxies have been classified in the extended Hubble system, andgroup memberships have been assigned based on velocity (where available)and morphology. About half the galaxies listed are likely members of oneof the nearby groups. The catalogs are complete to B(T) = 18, althoughthe completeness limits vary slightly from group to group. Based on Kingmodel fits to the surface density profiles, the core radii of the groupsrange from 0.3 to 1 Mpc, and central densities range from 120 to 1900galaxies Mpc exp-3 brighter than M(BT) = -12.5. Dynamical analysisindicates that all of the groups are likely to be gravitationally bound.
| Southern Galaxy Catalogue.
Not Available
| The Antlia cluster of galaxies and its environment - The Hydra I-Centaurus supercluster
The small Antlia cluster of galaxies was investigated by measuring manyradial velocities for galaxies from the Lauberts catalog in the Antliaregion. Apart from the Antlia cluster itself, four more small groupswere identified. These five systems form a tiny but not bound Antliamini-supercluster. The mini-supercluster consists of small groups andclusters and of a dispersed component of field galaxies. The five galaxysystems are also part of the large Hydra I-Centaurus supercluster. Thislarge supercluster belongs now to the class of well observed ones. Ithas a chain-like filamentary structure. This supercluster seems to beconnected to the Local Supercluster via two very extended but very loosegroups. The total structure is the triangle-shaped Virgo-HydraI-Centaurus supercluster.
| UBV photometry of 262 southern galaxies
Multiaperture photometry of 262 bright southern galaxies in the JohnsonUBV system is given. Most of these are south of -30 deg declination,although some northward to -10 deg are included. A total of 169 objectshave published radial-velocity determinations. These provide distancesand enable construction of color-magnitude diagrams for this subset ofobjects through a physical diameter of 2.0 kpc (with H = 100). Thetwo-color diagrams for the inner regions of the galaxies differ fromthose of integrated galaxies due to the color changes towards theircenters. Comparison with theoretical models of Larson and Tinsley (1978)suggest that the colors of the inner portions of most ellipticals andlenticulars are consistent with their having all stars formed at nearlyone epoch with little subsequent star formation, while for spiralslarger amounts of star formation, either in bursts or continuously, aresuggested. This simple picture is complicated by the presence of certainobjects having peculiar colors indicative of large amounts of recentstar formation.
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