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The Molonglo Southern 4 Jy Sample (MS4). II. ATCA Imaging and Optical Identification
Of the 228 sources in the Molonglo Southern 4 Jy sample (MS4), the 133with angular sizes <35" have been imaged at 5 GHz at 2"-4" resolutionwith the Australia Telescope Compact Array. More than 90% of the samplehas been reliably optically identified, either on the plates of the UKSchmidt Southern Sky Survey or on R-band CCD images made with theAnglo-Australian Telescope. A subsample of 137 sources, the SMS4,defined to be a close southern equivalent of the northern 3CRR sample,was found to have global properties mostly consistent with the northernsample. Linear sizes of MS4 galaxies and quasars were found to beconsistent with galaxy-quasar unification models of orientation andevolution.
| Nearby early-type galaxies with ionized gas. II. Line-strength indices for 18 additional galaxies
We previously presented a data-set of line-strength indices for 50early-type galaxies in the nearby Universe. The galaxy sample is biasedtoward galaxies showing emission lines, located in environmentscorresponding to a broad range of local galaxy densities, althoughpredominantly in low density environments. The present addendum enlargesthe above data-set of line-strength indices by analyzing 18 additionalearly-type galaxies (three galaxies, NGC 3607, NGC 5077 and NGC 5898were presented in the previous set). We measured 25 line-strengthindices, defined by the Lick IDS "standard" system (Trager et al. 1998,ApJS, 116, 1; Worthey & Ottaviani 1997, ApJS, 111, 377), for 7luminosity weighted apertures and 4 gradients of each galaxy. Thisaddendum presents the line-strength data-set and compares it with theavailable data in the literature.
| Evolution of smale scale systems of galaxies: X-ray detected E+S galaxy pairs.
Not Available
| Hi absorption in radio galaxies: effect of orientation or interstellar medium?
A search for Hi absorption has been made in 23 radio galaxies selectedfrom a complete sample. The observations were made with the AustraliaTelescope Compact Array (ATCA), with the Very Large Array (VLA) and forone galaxy with the Westerbork Synthesis Radio Telescope (WSRT). In fivegalaxies Hi absorption was detected. We investigate how the detectionrate is distributed among galaxies with different radio and opticalproperties. Among the Fanaroff-Riley (FR) type I radio galaxies, onlyone object (10 per cent of the total) was detected in Hi absorption. TheHi absorption in these objects is likely to come from a nuclear disc, asfound for other galaxies of this type (e.g. NGC 4261 and Hydra A). Thelow detection rate is consistent with the hypothesis (as suggested byoptical and X-ray data) that the `standard' parsec-scale, geometricallythick torus is not required in low-luminosity radio galaxies. This isconsistent with earlier optical work. In the case of FR type II powerfulradio galaxies, no Hi absorption has been detected in broad-line radiogalaxies, while three out of four narrow-line radio galaxies have beendetected (the one non-detection having quite a high upper limit). All ofthese are compact or small radio galaxies. To first order this isconsistent with the predictions of the unified schemes, assuming thatthe Hi absorption is caused by an obscuring torus. However, theindications of this being the only cause of the absorption are not verystrong. In particular, we find that in two of the three detected objectsthe Hi is blueshifted compared with the systemic velocity. In the thirdgalaxy (PKS 1549-79) two redshift systems (from the optical lines) arefound. The uncertainty in the systemic velocity derived from opticallines is discussed. Finally, by also considering data available in theliterature, we find a tendency for radio galaxies with a strongcomponent of young stellar population and far-infrared emission to showHi absorption. The overall richer interstellar medium that is likely tobe present in these galaxies may be a factor in producing theabsorption.
| ROSAT-HRI observations of six southern galaxy pairs
We present the detailed analysis of the X-ray data for 6 pairs, isolatedor in poor groups, observed at high resolution with the ROSAT HRI . Inall cases, the stronger X-ray source is associated with the brighterearly-type member and is extended. The extent varies from galactic togroup scale, from 3 (RR 210b) to 182 kpc( RR 22a). The fainter membersare detected only in two pairs, RR 210 and RR 259. Except for one case,no significant substructures have been detected in the X-ray maps,possibly also as a consequence of the poor statistics. The core radii ofthe X-ray surface brightness profiles are in the range 1-3 kpc. Thedistribution of the luminosities of galaxies in pairs encompasses a verywide range of both luminosities and LX / LBratios, in spite of the very small number of objects studied so far. Ourdata provide no evidence that pair membership affects the X-rayproperties of galaxies. Observation are discussed in the context of thepair/group evolution.
| Seeing Galaxies through Thick and Thin. I. Optical Opacity Measures in Overlapping Galaxies
We describe the use of partially overlapping galaxies to provide directmeasurements of the effective absorption in galaxy disks, independent ofassumptions about internal disk structure. The nonoverlapping parts ofthe galaxies and symmetry considerations are used to reconstruct, viadifferential photometry, how much background galaxy light is lost inpassing through the foreground disks. Extensive catalog searches andfollow-up imaging yield ~15-25 nearby galaxy pairs suitable for varyingdegrees of our analysis; 11 of the best such examples are presentedhere. From these pairs, we find that interarm extinction is modest,declining from AB~1 mag at 0.3RB25 toessentially zero by RB25; the interarm dust has ascale length consistent with that of the disk starlight. In contrast,dust in spiral arms and resonance rings may be optically thick(AB>2) at virtually any radius. Some disks have flatterextinction curves than the Galaxy, with AB/AI~1.6this is probably the signature of clumpy dust distributions. Even thoughtypical spirals are not optically thick throughout their disks, wherethey are optically thick is correlated with where they are mostluminous: in spiral arms and inner disks. This correlation betweenabsorption and emission regions may account for their apparent surfacebrightness being only mildly dependent on inclination, erroneouslyindicating that spirals are generally optically thick. Taken as anensemble, the opacities of spiral galaxies may be just great enough tosignificantly affect QSO counts, though not enough to cause theirhigh-redshift cutoff. Based in part on archival observations with theNASA/ESA Hubble Space Telescope (HST) obtained at the Space TelescopeScience Institute, which is operated by the Association of Universitiesfor Research in Astronomy, Inc., under NASA contract NAS5-26555.
| Parsec-scale structures of radio galaxies in the 2-Jy sample
In this paper we present the results of VLBI observations of six radiogalaxies belonging to the 2-Jy sample. The selected objects are 3C17,PKS 0620-52, PKS 0625-35, PKS 1318-43, PKS 1333-33 and 3C317. The firstis a high power radio galaxy and the remainder are all low powerobjects. Our observations were carried out with a set of differentarrays and frequencies, and cover a range of resolutions from a few masto a few tens of mas. Parsec-scale images are presented and discussed inthe light of unification for radio loud galaxies. Estimates for theintrinsic plasma speeds in these objects in the proximity of theparsec-scale core and their orientation to the line of sight are inagreement with the predictions from unified models and with theiroptical and X-ray properties. We will use H_o = 50 kms-1Mpc-1, q_o = 0 and S ~ nu -alpha throughout the paper.
| Dust in Spiral Galaxies: Comparing Emission and Absorption to Constrain Small-Scale and Very Cold Structures
The detailed distribution of dust in the disks of spiral galaxies isimportant to understanding the radiative transfer within disks and tomeasuring overall dust masses if significant quantities of dust areeither very opaque or very cold. We address this issue by comparingmeasures of dust absorption, using the galaxy-overlap technique in theoptical, with measures of the dust grains' thermal emission from 50-2000μm, using ISOPHOT on board Infrared Space Observatory (ISO) and SCUBAat the James Clerk Maxwell Telescope. We examine three spiral galaxiesprojected partially in front of E/S0 galaxies: AM 1316-241, NGC 5545,and NGC 5091 (for NGC 5091 we have only optical and ISO data). Adoptingan empirical exponential model for the dust distribution, we comparecolumn densities and dust masses derived from the absorption andemission techniques. This comparison is sensitive to the amount of dustmass in small, opaque structures, which would not contribute strongly toarea-weighted absorption measures, and to very cold dust, which wouldcontribute to optical absorption but provide only a small fraction ofthe submillimeter emission. In AM 1316-241, we find global dust massesof 2-5x10^7 M_solar, with the two techniques agreeing at the 50% level.NGC 5545 has about half this dust mass. The concordance of dust massesis well within the errors expected from our knowledge of the radialdistribution of dust and argues against any dominant part of the dustmass being so cold or opaque. The 50-2000 μm data are well fitted bymodified Planck functions with an emissivity law β=-2, at 21+/-2 K;a modest contribution from warmer dust is required to fit only the 50μm measurement of NGC 5545. We incorporate empirical corrections tothe flux scale of ISOPHOT P32 data, which can reach a factor 2 fromcomparison of IRAS and ISO fluxes for objects in two programs. We alsopresent 12 μm ISOCAM observations of these pairs. The light profilesat this wavelength exhibit shorter disk scale lengths than in theoptical. Comparison of Hα and 12 μm images of NGC 5545 indicatethat ISOCAM images are reliable tracers of star formation.
| 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.
| Observations of the radio jets in NGC 5090 (PKS B1318-434).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.279.1197L&db_key=AST
| Candidates for a southern extension of the Karachentsev catalogue of isolated pairs of galaxies.
Not Available
| Multicolor surface photometry of early-type galaxies. I.
We have obtained v,g,r and i CCD surface photometry for a sample of 109early-type galaxies. Many of the galaxies covered have no previouslypublished CCD or aperture photometry. Our surface brightness profilestypically extend down to a surface brightness ofμ_r_~24mag/arcsec^2^. Detailed comparisons with previously publishedwork, and internal and external error estimates for all quantities areprovided. The complete surface photometry data set is made available ina computer-readable form.
| 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.
| The supergalactic plane redshift survey
Redshift measurements, about 1000 of which are new, are presented for1314 galaxies in a survey toward the apex of the large-scale streamingflow for ellipticals. The velocity histogram shows that the excess ingalaxy number counts in this area is due to a substantial concentrationof galaxies with discrete peaks at V about 3000 km/s and V about 4500km/s. After correction for the sampling function, the centroid of thedensity distribution is found to be near V about 4500 km/s.Normalization to the more extensive SSRS survey, which was selected bythe same criteria, shows that the region studied contains a considerableoverdensity of galaxies from 2000 to 6000 km/s. This result is in goodagreement with the 'great attractor' model suggested by Lynden-Bell etal. (1988) which attributes the peculiar motions of elliptical galaxiesover a large region of space to an extensive mass overdensity whichincludes the Hydra-Centaurus and Pavo-Indus superclusters. The centroidof the density enhancement is also consistent with new data by Dresslerand Faber (1990) of peculiar motions of elliptical and spiral galaxies,both of which show a zero crossing of the Hubble line at approximately4500-5000 km/s.
| A radio and optical study of the interacting system NGC 5090-5091
The results of a radio and optical study of the interactingelliptical-spiral system NGC 5090-5091 are presented. The radio dataconsist of synthesis maps of 50-arcsec resolution constructed from dataobtained from the Fleurs and Molonglo synthesis telescopes. The mainconclusions to be drawn from the data are as follows. The rotation axisof NGC 5090 is most closely aligned with the photometric major axis. Theradio axis is inclined at about 70 deg to the rotation axis and isperpendicular to the line joining the two nuclei. The morphology of NGC5091 is consistent with tidal disruption by NGC 5090 in an initiallyunbound retrograde encounter. The interaction between NGC 5090 and NGC5091 may be responsible, via an inner Lindblad resonance, for enhancedfueling of the nuclear source in NGC 5090, and this may produce jetspropagating perpendicular to the orbital plane of NGC 5091.
| Southern Galaxy Catalogue.
Not Available
| Alignment of southern radio sources
Examples of alignment in the radio structure of strong close sources inthe southern sky are presented. The sources were mapped at highresolution using the telescopes of Sydney University and the MOSTtelescope. The sources with aligned radio structures are: 0211-479;0214-483; 1318-43 and 1322-42 (Cen-A). The possible physical mechanismsfor the observed parallel structures are identified, including parallelspin in galaxies with similar directions of angular momentum. Theorientation and position angles in the system Cen A and NGC 5090/91 areshown in a line drawing.
| A sample of southern binary galaxies
Data for 29 pairs of galaxies below declination -32 deg are presentedand analyzed. Although the sample is small, there is some suggestion ofan extended mass distribution.
| The elliptical/spiral pair of galaxies NGC 5090/5091
Studies of the elliptical galaxy NGC 5090 (PKS 1318-43) and the edge-onspiral NGC 5091 are described. A reduced Fleurs Synthesis Telescoperadio map of PKS 1318-43 is shown with a print of NGC 5090/5091 from theUK SERC Schmidt J survey film. Masses and tidal forces are examined. Forboth a bound and an unbound orbit, it is considered plausible that gasfrom NGC 5091 can be accreted into the nucleus of NGC 5090 in atimescale comparable to or shorter than that of the encounter. This gasmay form an accretion disk around the nucleus of NGC 5090 in the planeof the spiral. This disk, of unknown size, will at least define theejection axis of the beams powering the radio source and may also, byeventual infall onto the central massive object, fuel the energy source.
| 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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