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The star formation history of Seyfert 2 nuclei
We present a study of the stellar populations in the central ~200 pc ofa large and homogeneous sample comprising 79 nearby galaxies, most ofwhich are Seyfert 2s. The star formation history of these nuclei isreconstructed by means of state-of-the-art population synthesismodelling of their spectra in the 3500-5200 Åinterval. Aquasar-like featureless continuum (FC) is added to the models to accountfor possible scattered light from a hidden active galactic nucleus(AGN).We find the following. (1) The star formation history of Seyfert 2nuclei is remarkably heterogeneous: young starbursts, intermediate-ageand old stellar populations all appear in significant and widely varyingproportions. (2) A significant fraction of the nuclei show a strong FCcomponent, but this FC is not always an indication of a hidden AGN: itcan also betray the presence of a young, dusty starburst. (3) We detectweak broad Hβ emission in several Seyfert 2s after cleaning theobserved spectrum by subtracting the synthesis model. These are mostlikely the weak scattered lines from the hidden broad-line regionenvisaged in the unified model, given that in most of these casesindependent spectropolarimetry data find a hidden Seyfert 1. (4) The FCstrengths obtained by the spectral decomposition are substantiallylarger for the Seyfert 2s which present evidence of broad lines,implying that the scattered non-stellar continuum is also detected. (5)There is no correlation between the star formation in the nucleus andeither the central or overall morphology of the parent galaxies.
| Double-barred galaxies. I. A catalog of barred galaxies with stellar secondary bars and inner disks
I present a catalog of 67 barred galaxies which contain distinct,elliptical stellar structures inside their bars. Fifty of these aredouble-barred galaxies: a small-scale, inner or secondary bar isembedded within a large-scale, outer or primary bar. I providehomogenized measurements of the sizes, ellipticities, and orientationsof both inner and outer bars, along with global parameters for thegalaxies. The other 17 are classified as inner-disk galaxies, where alarge-scale bar harbors an inner elliptical structure which is alignedwith the galaxy's outer disk. Four of the double-barred galaxies alsopossess inner disks, located in between the inner and outer bars. Whilethe inner-disk classification is ad-hoc - and undoubtedly includes someinner bars with chance alignments (five such probable cases areidentified) - there is good evidence that inner disks form astatistically distinct population, and that at least some are indeeddisks rather than bars. In addition, I list 36 galaxies which may bedouble-barred, but for which current observations are ambiguous orincomplete, and another 23 galaxies which have been previously suggestedas potentially being double-barred, but which are probably not. Falsedouble-bar identifications are usually due to features such as nuclearrings and spirals being misclassified as bars; I provide someillustrated examples of how this can happen.A detailed statistical analysis of the general population of double-barand inner-disk galaxies, as represented by this catalog, will bepresented in a companion paper.Tables \ref{tab:measured} and \ref{tab:deproj} are only available inelectronic form at http://www.edpsciences.org
| Stellar population gradients in Seyfert 2 galaxies: northern sample
We use high signal-to-noise ratio long-slit spectra in theλλ3600-4700 range of the 20 brightest northern Seyfert 2galaxies to study the variation of the stellar population properties asa function of distance from the nucleus. In order to characterize thestellar population and other continuum sources (e.g. featurelesscontinuum, FC) we have measured the equivalent width, W, of sixabsorption features, four continuum colours and their radial variations,and performed spectral population synthesis as a function of distancefrom the nucleus. About half of the sample has CaIIK and G band W valuessmaller at the nucleus than at 1 kpc from it, owing to a youngerpopulation and/or FC. The stellar population synthesis shows that, whileat the nucleus, 75 per cent of the galaxies present contribution >20per cent of ages <=100 Myr and/or of an FC, this proportion decreasesto 45 per cent at 3 kpc. In particular, 55 per cent of the galaxies havea contribution >10 per cent of the 3-Myr/FC component (a degeneratecomponent in which one cannot separate what is caused by an FC or by a3-Myr stellar population) at the nucleus, but only 25 per cent of themhave this contribution at 3 kpc. As a reference, the stellar populationof 10 non-Seyfert galaxies, spanning the Hubble types of the Seyfert(from S0 to Sc) was also studied. A comparison between the stellarpopulation of the Seyferts and that of the non-Seyferts shows systematicdifferences: the contribution of ages younger than 1 Gyr is in mostcases larger in the Seyfert galaxies than in non-Seyferts, not only atthe nucleus but up to 1 kpc from it.
| A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| Stellar populations in Seyfert 2 galaxies. I. Atlas of near-UV spectra
We have carried out a uniform spectroscopic survey of Seyfert 2 galaxiesto study the stellar populations of the host galaxies. New spectra havebeen obtained for 79 Southern galaxies classified as Seyfert 2 galaxies,7 normal galaxies, and 73 stars at a resolution of 2.2 Å over thewavelength region 3500-5300 Å. Cross-correlation between thestellar spectra is performed to group the individual observations into44 synthesis standard spectra. The standard groups include a solarabundance sequence of spectral types from O5 to M3 for dwarfs, giants,and supergiants. Metal-rich and metal-weak F-K giants and dwarfs arealso included. A comparison of the stellar data with previouslypublished spectra is performed both with the individual spectra and thestandard groups. For each galaxy, two distinct spatial regions areconsidered: the nucleus and the external bulge. Spectroscopic variationsfrom one galaxy to another and from the central to the external regionare briefly discussed. It is found that the central region of a Seyfert2 galaxy, after subtracting the bulge stellar population, always shows anear-UV spectrum similar to one of three representative categories: a)many strong emission lines and only two visible absorption lines (Ca IiK and G band) (Sey2e); b) few emission lines, many absorption lines, anda redder continuum than the previous category (Sey2a); c) an almost flatcontinuum and high-order Balmer lines seen in absorption (Sey2b). Theproportion of Seyfert 2 galaxies belonging to each class is found to be22%, 28%, and 50% respectively. We find no significative differencesbetween morphology distributions of Seyfert 2 galaxies with Balmer linesdetected in absorption and the rest of the sample. This quick lookthrough the atlas indicates that half of Seyfert 2 galaxies harbour ayoung stellar population (about or less than 100 Myr) in their centralregion, clearly unveiled by the high order Balmer series seen inabsorption. Based on observations collected at the European SouthernObservatory, Chile (ESO 65.P-0014(A)). Tables 1-3 and 8 and Fig. A.1(Appendix A) are only available in electronic form athttp://www.edpsciences.org
| 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.
| Molecular Gas, Morphology, and Seyfert Galaxy Activity
We probe the cause of the elevated star formation in host galaxies ofSeyfert 2 nuclei compared with Seyfert 1 hosts and with field galaxies.12CO (1--0) observations of a large sample of Seyfert galaxies indicateno significant difference in the total amount of molecular gas as afunction of the Seyfert nuclear type, nor are Seyfert galaxiessignificantly different in this regard from a sample of field galaxiesonce selection effects are accounted for. Therefore, the total amount ofmolecular gas is not responsible for the enhanced star-forming activityin Seyfert 2 hosts. To probe how this gas is being converted moreefficiently into stars in Seyfert 2 hosts than in the other galaxies, weinvestigate the occurrence of bars, interactions, and distortedmorphologies among Seyfert galaxies. We find a significantly higher rateof asymmetric morphologies for Seyfert 2 galaxies with respect toSeyfert 1 galaxies and field galaxies. Relative to field galaxies, theeffect is at a greater than 99.9% confidence level. The presence ofasymmetric morphologies in individual Seyfert galaxies is correlatedwith their tendency to exhibit enhanced star-forming activity. Theseresults suggest that asymmetric morphologies are an important cause forthe link between Seyfert type and star-forming activity: bars anddistortions in Seyfert 2 hosts are likely both to enhance star-formingactivity and to funnel gas into the nuclear region, thus obscuring andpossibly contributing to the feeding of the active nucleus.
| 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.
| 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.
| Spectroscopic studies of emission line galaxies.
Not Available
| Photometrically distinct nuclei in elliptical and early-type disks galaxies.
Not Available
| The dependence of the cool matter content on galaxy morphology in galaxies of types E/S0, S0, and SA
Using the material assembled in earlier papers, we examine the manner inwhich the interstellar matter content varies along the Hubble sequencefrom S0 galaxies to Sa galaxies selected from the RSA2 compilation. Forthis we make use of a new and more detailed classification which isdescribed here as applied to these early disk/spiral galaxies. Theprominence of the disk in S0's and the visibility of features (H IIregions) in the Sa's serve as the basis for the subtypes. Three S0categories: subtle, intermediate, and pronounced, and four Sadescriptors: very early, early, intermediate, and late are assigned tothe galaxies. It is found that the total amount of hydrogen (H I + H2)is a function of subtype, being low in the S0's and rising smoothly fromthe early Sa's to the later Sa's. The average surface density ofhydrogen exceeds 3 solar masses/pc-squared only in the latest subtypesof the Sa's. We conclude that the prominence of the disk of a galaxyclosely follows the amount of cool gas which the disk contains.
| Metric characteristics of nuclear rings and related features in spiral galaxies
The metric properties of nuclear rings, pseudorings, spirals, and barsare discussed in the context of resonance theory and are used to gaugethe range of sizes for such features. The nuclear rings and pseudoringsof strongly barred SB and SAB galaxies have a wide range in lineardiameter; the mean diameter is about 1.1 kpc for a sample of 20 objects.We suggest that there are clear analogs of the nuclear rings of stronglybarred spirals in both weakly barred (SAB) and nonbarred (SA) spirals.The size ratios of nuclear rings with respect to outer rings andpseudorings, as well as morphological characteristics, are bestexplained if outer rings and pseudorings are linked to the outerLindblad resonance, and nuclear rings, pseudorings, and spirals arelinked to the inner Lindblad resonance. Nuclear bars are oftenassociated with nuclear rings and spirals, but also can existindependently of such features. We present a list of 13 double-barredgalaxies and discuss the significance of the phase angle of the nuclearbar with respect to the primary bar.
| 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.
| On the transparency of the inner regions of early-type spiral galaxies
Surface photometry of 17 inclined Sa-Sb galaxies with prominent bulgesfrom the ESO-LV Data Base has been analyzed with the aim of detectingthe possible effects of a hypothetical absorbing layer bisecting thecentral bulge. Our method is based on looking for an asymmetry betweenthe photometric profiles of the two semi-minor axes, and iscomplementary to the surface brightness inclination test which, forearly spirals with bright bulges, is confused by the very presence ofthese bulges. None of the galaxies in our sample shows evidence of acontinuous, near-opaque layer reaching the very center. Our conclusionsare strengthened by two additional, well-studied objects, M 31 and M104; our results indicate a lower obscuration in the central regions ofearly spirals with strong bulges compared to later types, and contributeto discriminate between competing models of light obscuration withingalactic disks.
| 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.
| Interstellar matter in early-type galaxies. I - The catalog
A catalog is given of the currently available measurements ofinterstellar matter in the 467 early-type galaxies listed in the secondedition of the Revised Shapley-Ames Catalog of Bright Galaxies. Themorphological type range is E, SO, and Sa. The ISM tracers are emissionin the following bands: IRAS 100 micron, X-ray, radio, neutral hydrogen,and carbon monoxide. Nearly two-thirds of the Es and SOs have beendetected in one or more of these tracers. Additional observed quantitiesthat are tabulated include: magnitude, colors, radial velocity, centralvelocity dispersion, maximum of the rotation curve, angular size, 60micron flux, and supernovae. Qualitative statements as to the presenceof dust or emission lines, when available in the literature, are given.Quantities derivative from the observed values are also listed andinclude masses of H I, CO, X-ray gas, and dust as well as an estimate ofthe total mass and mass-to-luminosity ratio of the individual galaxies.
| 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.
| Revised supernova rates in Shapley-Ames galaxies
Observations of 855 Shapley Ames galaxies made from November 1, 1980 toOctober 31, 1988, together with improved supernova luminosities, havebeen used to derive the frequency of supernovae of different types, andthe results are presented in tables. From a uniform database of 24supernovae discovered, the following SN rates are found, expressed in SNper century per 10 to the 10th L(B)(solar): SN Ia, 0.3; SN Ib, 0.3; andSN II, 1.0. The present data confirm the relatively high frequency of SNII in late-type galaxies that has been found by many previousinvestigators.
| The stellar-free emission component in galactic nuclei - At low-levels, evidence for shock ionization
The emission-line component in a sample of 92 galaxies was isolatedusing stellar absorption templates built from emission-free star clusterspectra and taking into account all sources of reddening extrinsic tothe line emitting regions, and the emission line properties werestatistically analyzed. Three characteristic average spectra were built,including those corresponding to nuclear H II regions, objectsidentified as LINERs, and extreme low-level emission galaxies with W(em)of not greater than 2 A. For the latter, line measurements were pusheddown to very low level. The measurements of the ratio between forbiddenS II line and forbidden S III line indicate that, in the extremelow-level emission galaxies, the shock ionization is the mechanism atwork.
| Magnitude calibration in the Cordoba Atlas
Not Available
| Population synthesis in galactic nuclei using a library of star clusters
A novel galactic-nucleus population-synthesis technique is described anddemonstrated. The procedure is applicable to normal nuclei of E/S0 andspiral galaxies and employs a data base of integrated star-clusterspectra, thus reducing the number of parameters in the analysis to two(age and metallicity), as proposed by Bica and Alloin (1986). Resultsare presented in extensive tables and spectra and discussed in detail.The populations in the E/S0s with normal metallicity/luminosityrelations are found to comprise mainly stars older than 10 Gyr, withsome as young as about 5 Gyr; younger groups are superimposed on older,solar-metallicity populations in the bluer spirals. In NGC 5236, forexample, 87 and 57 percent of the flux at 400 and 900 nm, respectively,is attributed to stars younger than about 300 Myr.
| Analysis of absorption-line spectra in a sample of 164 galactic nuclei
Spectral observations in the 3700-8000 A range of 154 normal galacticnuclei, two amorphous galaxies, and eight intrinsically faint activenuclei whose visible spectrum is dominated by the stellar component arediscussed. A typical red, strong-lined spectrum is found for each groupfrom E to Sb in the -23.2 to -19.0 luminosity range, as well as for thevery luminous Sbc and Sc galaxies, although a few atypical nucleiexhibit variable contents of bluer stellar components. No prototype canbe assigned to the Sbc and Sc galaxies in the -21.9 to -19.0 luminosityrange. Analysis of the equivalent widths shows that the CN 4216-4250 Afeature has the largest dynamical range as a function of metallicity. Itis suggested that young stars are responsible for the blue colors inNGC2865, 4382, and 5102, and that metal-poor stars do not contributesignificantly.
| UBVRI photometry of active galaxies. I - Observations
A total of 693 UBVRI photoelectric observations for 91 active galaxiesare reported. These observations were secured as part of a one-yearmonitoring program. Objects are classified in three classes according totheir degree of variability; 52 percent of the galaxies did not show asignificant variability (class 1); 12 percent showed some variations(class 2); and 35 percent displayed significant variations (class 3). Acomparison with four other sets of photometric values is carried out.
| Near-infrared spectral properties of star clusters and galactic nuclei
A powerful method for the correction of CCD fringes in the near-IR ispresented, together with 6300-9700 A CCD spectra of 30 star clusterscovering the 1 million to 16.5 billion age range and observations of 62galactic nuclei in galaxies of E to Sc morphological type. An analysisof the star cluster sample indicates that, in the near-IR spectralrange, metallicity is the dominant parameter. Attention is given to thesecond-order effects produced by age. Grid predictions as a function ofmetallicity and age are given for five metallic features and for thecontinuum distribution.
| Study of a complete sample of galaxies. II - Spectroscopy of the nuclei
Spectroscopic observations of a complete sample of 320 galaxies (fromthe Revised Shapley Ames Catalog of Sandage and Tammann, 1981) withdeclination less than or equal to +20 deg, galactocentric velocity lessthan 3000 km/s, and absolute magnitude brighter than M(B) = -21.0 arereported. The 400-700-nm spectra were obtained with resolution about 1nm using the Boller and Chivens spectrograph and image-dissector scannerat the Cassegrain focus of the 1.52-m telescope at ESO on 36 nightsduring 1980-1983. The data are presented in extensive tables and spectraand briefly characterized. The majority of the spectra are classified asH II regions ionized by hot stars or as Seyfert-like nebulosities.
| Is NGC 3347 a variable spiral galaxy?
UBVRI multiaperture photometry of the spiral galaxies NGC 3347, NGC3354, and NGC 3358 is presented. The variability hypothesis for NGC 3347suggested by Dottori (1979) is discussed. It is concluded that NGC 3347is not a variable spiral galaxy.
| 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.
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