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Molecular gas in the galaxy cluster Abell 262. CO observations of UGC 1347 and other galaxies of the cluster
We present millimeter CO line emission observations of 12 galaxieswithin the Abell 262 cluster, together with L_FIRdata, in the context of a possible molecular gas deficiency within theregion of the cluster center. Several indications of the presence ofsuch a deficiency are highlighted and connected to a model ofcirrus-like cloud stripping. The model predicts a drop in the average100 μm flux density of galaxies in the core of the cluster comparedto the average 100 μm flux density in the outer regions, which isactually indicated in the IRAS data of the cluster members. This drop isexplained by the decrease in the total hydrogen column density N(H) and,therefore, also includes a decrease in the molecular gas content. Inaddition to results for the global CO content of the galaxy sample,high-resolution interferometric CO(1-0) observations of one of thecluster members, UGC 1347, exemplify the spatial distribution of themolecular gas in a galaxy of the cluster. With these observations, itwas possible to confirm the existence of a bright off-nuclearCO-emission source and to derive molecular masses and line ratios forthis source and the nucleus.
| 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
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| The Beta Problem: A Study of Abell 262
We present an investigation of the dynamical state of the cluster A262.Existing optical line-of-sight velocities for select cluster galaxieshave been augmented by new data obtained with the Automated Multi-ObjectSpectrograph at Lick Observatory. We find evidence for a virializedearly-type population distinct from a late-type population infallingfrom the Pisces-Perseus supercluster ridge. We also report on a tertiarypopulation of low-luminosity galaxies the velocity dispersion of whichdistinguishes them from both the early- and late-type galaxies. Wesupplement our investigation with an analysis of archival X-ray data. Atemperature is determined using ASCA GIS data, and a gas profile isderived from ROSAT HRI data. The increased statistics of our sampleresults in a picture of A262 with significant differences from earlierwork. A previously proposed solution to the ``β-problem'' in A262in which the gas temperature is significantly higher than the galaxytemperature is shown to result from using too low a velocity dispersionfor the early-type galaxies. Our data present a consistent picture ofA262 in which there is no ``β-problem,'' and the gas and galaxytemperature are roughly comparable. There is no longer any requirementfor extensive galaxy-gas feedback to drastically overheat the gas withrespect to the galaxies. We also demonstrate that entropy floor modelscan explain the recent discovery that the β values determined bycluster gas and the cluster core radii are correlated.
| 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.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| Determination of Galaxy Spin Vectors in the Pisces-Perseus Supercluster with the Arecibo Telescope
We use H I observations made with the upgraded Arecibo 305 m telescopein 1998 August to obtain accurate spin vector determinations for 54nearly edge-on galaxies in the Minnesota Automated Plate ScannerPisces-Perseus Survey. We introduce a simple observational technique fordetermining the sense of rotation for galaxies even when their H I disksare not fully resolved. We examined the spin vector distribution ofthese 54 galaxies for evidence of preferential galaxy alignments. We usethe Kuiper statistic, a variant of the Kolmogorov-Smirnov statistic, todetermine the significance of any anisotropies in the distribution ofgalaxy spin vectors. The possibility of ``spin vector domains'' is alsoinvestigated. We find no significant evidence of preferential galaxyalignments in this sample. However, we show that the small sample sizeplaces weak limits on the level of galaxy alignments.
| Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
| The Universality of the Fundamental Plane of E and S0 Galaxies: Spectroscopic Data
We present central velocity dispersion measurements for 325 early-typegalaxies in eight clusters and groups of galaxies, including newobservations for 212 galaxies. The clusters and groups are the A262,A1367, Coma (A1656), A2634, Cancer, and Pegasus Clusters and the NGC 383and NGC 507 Groups. The new measurements were derived frommedium-dispersion spectra that cover 600 Å centered on the Mg I btriplet at lambda ~ 5175 Å. Velocity dispersions were measuredusing the Tonry & Davis cross-correlation method, with a typicalaccuracy of 6%. A detailed comparison with other data sources is made.
| The Universality of the Fundamental Plane of E and S0 Galaxies: Sample Definition and I-Band Photometric Data
As part of a project to compare the fundamental plane and Tully-Fisherdistance scales, we present here I-band CCD photometry for 636early-type galaxies in eight clusters and groups of galaxies. These arethe A262, A1367, Coma (A1656), A2634, Cancer and Pegasus Clusters, andthe NGC 383 and NGC 507 Groups. Sample selection, cluster properties,and cluster membership assignment criteria are discussed. We presentphotometric parameters that are used in the fundamental plane relation,the effective radius r_e, and the effective surface brightness mu_e, asderived from a r^1/4 fit to the observed radial photometric profile ofeach galaxy. A comparison with similar data found in the literature forthe Coma Cluster shows that large systematic uncertainties can beintroduced in the measurement of r_e and mu_e by the particular methodused to derive those parameters. However, the particular combination ofthese two parameters that enters in the fundamental plane relation is aquantity that can be measured with high accuracy.
| Galaxy Alignments in the Pisces-Perseus Supercluster Revisited
A search for preferential galaxy alignments in the Pisces-PerseusSupercluster (PPS) is made using the Minnesota Automated Plate ScannerPisces-Perseus Survey (MAPS-PP). The MAPS-PP is a catalog of ~1400galaxies with a (roughly) isophotal diameter greater than 30"constructed from digitized scans of the blue and red plates of thePalomar Observatory Sky Survey covering the PPS. This is the largestsample of galaxies applied to a search of galaxy alignments in thissupercluster, and it has been used in combination with previouslypublished redshifts to construct the deepest PPS galaxy luminosityfunction to date. While previous studies have relied extensively oncatalogs with visually estimated parameters for both sample selectionand determination of galaxy orientation, the MAPS-PP uses selectioncriteria and measurements that are entirely machine and computer based.Therefore, it is not susceptible to some of the biases, such as thediameter inclination effect, known to exist in some other galaxycatalogs. The presence of anisotropic galaxy distributions is determinedby use of the Kuiper statistic, a robust alternative to the chi^2statistic more traditionally used in these studies. Three statisticallysignificant anisotropic distributions are observed. The reddest galaxiesare observed to be oriented preferentially perpendicular to the locallarge-scale structure. The bluest galaxies near the supercluster planeare observed to have an anisotropic position angle distribution.Finally, a weak trend for the median position angle of color-selectedgalaxy subsamples to ``twist'' with increasing distance from the PPSplane is observed. These position angle distribution anisotropies areweak and are not consistent with any single primordial or modern-eragalaxy alignment mechanism, although a mixture of such mechanisms is notruled out.
| 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.
| Photoelectric UBV Photometry of Galaxies in the Clusters Pegasus I, Pegasus II, Abell 262, Abell 1367, and Abell 2197-9
This paper presents photoelectric UBV multiaperture photometry of 144galaxies, 139 of which are associated with six nearby bright clusters.The observations were made at the McDonald Observatory from 1986September to 1987 November and were part of the production of the ThirdReference Catalogue of Bright Galaxies (RC3). The observations were usedto compute total magnitudes and color indices published in RC3. Theobservations can also be used to calibrate CCD images.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| A survey of the Pisces-Perseus supercluster. V - The declination strip +33.5 deg to +39.5 deg and the main supercluster ridge
Measurements of 544 radial velocities, 229 optical and 315 in the 21 cmH I line, are presented for galaxies, mostly in the declination stripbetween +33.5 and +39.5 deg in the region of the Pisces-Perseussupercluster. These are combined with other available data toinvestigate the linear structure identified as the main superclusterridge. The main ridge of the supercluster extends at least 50/h Mpcbefore it disappears into the zone of avoidance east of Perseus.Confinement both on the plane of the sky and in the velocity dimensionimply an axial ratio of greater than 10:1 and an inclination withrespect to the plane of the sky of less than about 12 degrees. Therelative proximity, low inclination to the plane of the sky, and highcontrast relative to the foreground and background, help to make thePisces-Perseus filament one of the most prominent features in theextragalactic sky on large scales.
| Optical positions and 327 MHz flux-densities of UGC galaxies in selected Westerbork fields
The study presents accurate optical positions of 421 UGC galaxies whichare used to search for 30 92-cm WSRT fields observed for emission fromthese galaxies. Good 92-cm flux densities were obtained for 140galaxies, marginal flux densities for 71 galaxies, and upper limits for210 galaxies. For 35 galaxies, spectral indices in the decimeterwavelength range are determined. The mean spectral index for spiralgalaxies (0.72 +/- 0.03) is very similar to that of elliptical galaxies(0.64 +/- 0.10). The four multiple systems in the sample have a muchflatter spectral index (-0.21 +/- 0.07), from which the presence of asignificant thermal component in their total radio emission issuggested. Comparison with IRAS results show that about half of thegalaxies detected at radio wavelengths are detected in the FIR. It isproposed that some spiral galaxies are anomalously weak in the IR ascompared with their radio brightness.
| 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.
| Multifrequency windows on spiral galaxies. II - The A262 and Cancer clusters
New photometrical data (U,B,V and H bands) are presented for about 100spiral galaxies in the A262 and Cancer clusters. The data are used tostudy the dependence of radio continuum to H band and FIR to H bandratios on the color index U - B, taken as an indicator of the starformation history in galaxy disks. Both parameters are found to increasein bluer galaxies, in agreement with the results obtained for otherclusters or field galaxies. The radio continuum activity of spiralgalaxies in the Cancer cluster is not enhanced like in other clusterspirals. A study of the reliability of CCD surface photometry isreported, based on the comparison of two sets of observations obtainedwith different telescopes.
| H I content and FIR emission of S0 galaxies
A sample of 252 S0 galaxies is used to study the relationship between HI content and far-IR emission. Logarithms of the H I content versus thefar-IR emission are employed statistically to develop a best-fit linearregression line which is compared to a slope of approximately unity. Theslopes are different for S0 and SB0 galaxies versus S0/a and SB0/agalaxies. The distribution of the 60-100 micron flux ratio is notsignificantly affected by the presence or absence of bars nor by thedifferences between the S0 and S0/a systems. The flux ratio is higherthan the critical value of Helou in 34 percent of the cases, and thevalue holds when nuclear emission is taken into account. In cases wherethe critical value is exceeded, most far-IR emissions are expected to bedue to star formation. S0 galaxies are generally found to have a normalISM, except where the systems have accreted their H I gas. Systems withdisproportionate FIR emission can be considered galaxies that areexperiencing enhanced star formation or that have had their H I gasswept away.
| HI observations of galaxies in nearby Zwicky clusters
The results of a long term project of H I observations of galaxieswithin the boundaries of nearby Zwicky clusters are presented. Thedetection rate is rather low (233 out of 618, i.e., 38 percent) ascompared to other surveys carried out recently. Most of the radialvelocities of the detected galaxies are new determinations. The largespread in radial velocities for many of these clusters is a strongindication for the presence of several foreground and/or backgroundgalaxies.
| On the relationship between radio emission and optical properties in early-type galaxies
To study the origin of radio activity in early-type galaxies, thepossible dependence of their radio emission on basic optical parameters,such as the absolute magnitude, the central velocity dispersion sigma,and the mean surface brightness mu is explored. A sample of 743 E and SOgalaxies is used which is based on three independent radio surveys ofoptically selected galaxies with virtually complete information onmagnitudes, morphological types, redshift distances, diameters, andradio fluxes. For both E and SO galaxies, only the absolute magnitudeappears to be directly related to the radio activity, while sigma and mudo not. Also, a significant dependence of the apparent flattening onradio power is confirmed for E galaxies. Some relevant implications ofthese results are discussed.
| Alignments of galaxies in the Perseus supercluster
The relative orientations of the galaxies belonging to the Perseussupercluster are investigated. The result is a lack of alignment in anypreferred direction of the supercluster galaxies (ellipticals, spiralsand both), except in a selected region of the supercluster, whosesignificance is low. Moreover no evidence of anisotropy in the relativeorientations of neighboring galaxies has been found.
| The statistical distribution of the neutral-hydrogen content of S0 galaxies
The distribution of relative global H I content M(H I)/L(B) has beenderived for galaxies of types S0 and S0/a using a data set derived fromrecent H I observations in the literature. The relative H I content ofthese galaxies is found to show transitional properties betweenelliptical and spiral galaxies. The distribution of M(H I)/L(B) forS0/a's resembles that for spirals, and these galaxies may represent'fossil' spirals, i.e., galaxies whose gas has been severely depleted bystar formation. The distribution for S0's, however, resembles that forellipticals. The form of this distribution strongly suggests an externalorigin for most of the H I in S0 galaxies.
| The evolution of galaxies in clusters. IV - Photometry of 10 low-redshift clusters
Colors and magnitudes, obtained from Palomar 48 inch (1.2 m) Schmidtplates in the J and F bands, and morphological types are presented forgalaxies in the cores of 10 nearby clusters of galaxies. In the typicalcluster, the sample includes all galaxies within a radius of 1.5 Mpc(assuming H(0) = 50 km/s/Mpc) of the cluster center and brighter than J= 17.5.The accuracy of the photometry varies with cluster, but mostmagnitudes are accurate to 0.10 mag, and typical errors in the colorsare of the same order. As expected, the colors of the elliptical and S0galaxies show a narrow dispersion about a mean color which decreaseswith magnitude. However, the colors of the spiral galaxies are notentirely as expected, having a smaller dispersion than would have beenpredicted from their morphological types.
| Gas deficiency in cluster galaxies - A comparison of nine clusters
The available 21 cm line data in the literature for galaxies in nineclusters is combined with new high-sensitivity observations of 51galaxies in five of the nine clusters in order to test fordiscriminating circumstances between those clusters which show H Ideficiency among their spiral population and those which do not. An H Ideficiency for the complete cluster sample is derived employing acomparison sample of galaxies chosen from the Catalog of IsolatedGalaxies. The deficiency and its radial dependence is summarized foreach cluster and a composite. A comparison of the environments indifferent clusters leads to the conclusion that the occurrence of H Ideficiency is correlated with the presence of a hot X-ray intraclustermedium, and that an ongoing interaction process is active through thecores of X-ray clusters.
| The subluminous Type I supernova 1957a in NGC 2841
SN 1957a in NGC 2841 has been considered to have been a Type IIsupernova because hydrogen lines were identified in its spectrum. It isshown that the spectrum did not contain hydrogen lines, and was that ofa Type I supernova. The post-peak decline of the light curve also waslike that of a Type I, but SN 1957a appears to have had a narrowlight-curve peak and to have been subluminous by perhaps 2 mag.
| Radio and optical observations of 9 nearby Abell clusters - A262, A347, A569, A576, A779, A1213, A1228, A2162, A2666
A survey is made of 61 Abell clusters included in the HEAO-2 satelliteobserving program at 1.4 GHz. Data are presented on the nine clusters ofdistance class 1 and 2. With a view to establishing galaxy morphologiesand extending the sample of the galaxies with known velocities, platesand spectra are obtained with a 152-cm telescope. The bivariate radioluminosity function of the cluster galaxies is determined for the threemorphological types, E, SO, and S plus Irr, dividing these into threedifferent classes of absolute optical magnitude. The radio luminosityfunctions of E and SO galaxies in present clusters do not differ fromthose of E and SO galaxies in clusters having higher richness. Someevidence exists that spiral galaxies in clusters have a lowerprobability of being radio sources than field ones. Also included is abrief discussion of the sizes of cluster radio sources and thecorrelation between radio emission and the presence of emission linesfrom a galaxy.
| The radial distribution of morphological types of galaxies in X-ray clusters
Galaxies have been classified in six clusters which are known to emitX-rays. It is found that in all cases the ratio of the surface densityof spiral galaxies to that of S0's increases outward. Moreover, there isa correlation between the velocity dispersion of the galaxies in acluster and the overall proportion of S0's among disk galaxies. Thesefacts are interpreted as support for Gunn and Gott's (1972) hypothesisthat S0's are produced from spirals by a process in which theinterstellar gas in spirals is swept out as these galaxies move throughthe hot gas presumed to be responsible for the X-ray emission. A furthertest of this hypothesis is suggested, and redshift measurements arepresented for galaxies in several X-ray clusters.
| On the composition of stellar associations.
Not Available
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