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|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.
|Kinematics of AWM and MKW Poor Clusters|
We have measured 1365 redshifts to a limiting magnitude of R~15.5 in 15AWM/MKW clusters and have collected another 203 from the literature inMKW 4s, MKW 2, and MKW 2s. In AWM 7 we have extended the redshift sampleto R~18 in the cluster center. We have identified 704 cluster members in17 clusters; 201 are newly identified. We summarize the kinematics anddistributions of the cluster galaxies and provide an initial discussionof substructure, mass and luminosity segregation, spectral segregation,velocity-dispersion profiles, and the relation of the central galaxy toglobal cluster properties. We compute optical mass estimates, which wecompare with X-ray mass determinations from the literature. The clustersare in a variety of dynamical states, reflected in the three classes ofbehavior of the velocity-dispersion profile in the core: rising,falling, or flat/ambiguous. The velocity dispersion of the emission-linegalaxy population significantly exceeds that of the absorption-linegalaxies in almost all of the clusters, and the presence ofemission-line galaxies at small projected radii suggests continuinginfall of galaxies onto the clusters. The presence of a cD galaxy doesnot constrain the global cluster properties; these clusters are similarto other poor clusters that contain no cD. We use the similarity of thevelocity-dispersion profiles at small radii and the cD-like galaxies'internal velocity dispersions to argue that cD formation is a localphenomenon. Our sample establishes an empirical observational baselineof poor clusters for comparison with simulations of similar systems.Observations reported in this paper were obtained at the Multiple MirrorTelescope Observatory, a facility operated jointly by the University ofArizona and the Smithsonian Institution; at the Whipple Observatory, afacility operated jointly by the Smithsonian Astrophysical Observatoryand Harvard University; and at the WIYN Observatory, a joint facility ofthe University of Wisconsin-Madison, Indiana University, YaleUniversity, and the National Optical Astronomy Observatories.
|The calibration of the extragalactic distance scale: methods and problems.|
|The IRAS PSCz dipole|
We use the PSCz IRAS galaxy redshift survey to analyse the cosmologicalgalaxy dipole out to a distance of 300h-1Mpc. The masked areais filled in three different ways, first by sampling the whole sky atrandom, secondly by using neighbouring areas to fill a masked region,and thirdly using a spherical harmonic analysis. The method of treatmentof the mask is found to have a significant effect on the finalcalculated dipole. The conversion from redshift space to real space isaccomplished by using an analytical model of the cluster and voiddistribution, based on 88 nearby groups, 854 clusters and 163 voids,with some of the clusters and all of the voids found from the PSCz database. The dipole for the whole PSCz sample appears to have convergedwithin a distance of 200h-1Mpc and yields a value forβΩ0.6b0.750.11-0.08, consistent with earlier determinations from IRAS samples bya variety of methods. For b=1, the 2σ range forΩ0 is 0.43-1.02. The direction of the dipole is within13° of the cosmic microwave background (CMB) dipole, the mainuncertainty in direction being associated with the masked area behindthe Galactic plane. The improbability of further major contributions tothe dipole amplitude coming from volumes larger than those surveyed heremeans that the question of the origin of the CMB dipole is essentiallyresolved.
|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.
|The I-Band Tully-Fisher Relation for SC Galaxies: 21 Centimeter H I Line Data|
A compilation of 21 cm line spectral parameters specifically designedfor application of the Tully-Fisher (TF) distance method is presentedfor 1201 spiral galaxies, primarily field Sc galaxies, for which opticalI-band photometric imaging is also available. New H I line spectra havebeen obtained for 881 galaxies. For an additional 320 galaxies, spectraavailable in a digital archive have been reexamined to allow applicationof a single algorithm for the derivation of the TF velocity widthparameter. A velocity width algorithm is used that provides a robustmeasurement of rotational velocity and permits an estimate of the erroron that width taking into account the effects of instrumental broadeningand signal-to-noise. The digital data are used to establish regressionrelations between measurements of velocity widths using other commonprescriptions so that comparable widths can be derived throughconversion of values published in the literature. The uniform H I linewidths presented here provide the rotational velocity measurement to beused in deriving peculiar velocities via the TF method.
|The I-Band Tully-Fisher Relation for SC Galaxies: Optical Imaging Data|
Properties derived from the analysis of photometric I-band imagingobservations are presented for 1727 inclined spiral galaxies, mostly oftypes Sbc and Sc. The reduction, parameter extraction, and errorestimation procedures are discussed in detail. The asymptotic behaviorof the magnitude curve of growth and the radial variation in ellipticityand position angle are used in combination with the linearity of thesurface brightness falloff to fit the disk portion of the profile. TotalI-band magnitudes are calculated by extrapolating the detected surfacebrightness profile to a radius of eight disk scale lengths. Errors inthe magnitudes, typically ~0.04 mag, are dominated by uncertainties inthe sky subtraction and disk-fitting procedures. Comparison is made withthe similar imaging database of Mathewson, Ford, & Buchhorn, both aspresented originally by those authors and after reanalyzing theirdigital reduction files using identical disk-fitting procedures. Directcomparison is made of profile details for 292 galaxies observed incommon. Although some differences occur, good agreement is found,proving that the two data sets can be used in combination with onlyminor accommodation of those differences. The compilation of opticalproperties presented here is optimized for use in applications of theTully-Fisher relation as a secondary distance indicator in studies ofthe local peculiar velocity field.
|Groups of galaxies. III. Some empirical characteristics.|
|The Interchangeability of CO and H I in the Tully-Fisher Relation|
We investigate the viability and precision of using ^12CO (J = 1 -->0) emission lines from galaxies in lieu of 21 cm emission in theTully-Fisher distance indicator (TF). Here we combine CO data gatheredspecifically for Tully-Fisher analysis with I-band photometry (both newand from the literature) for cluster galaxies between 3500 and 8000 kms^-1 and compare the luminosity-line width relation using CO with theresults of recent, large TF surveys using H i and Hα. We cull someCO data as suggested by previously published numerical simulations andfind that CO line widths, with corrections for turbulence andnoise-broadening on the order of 35 km s^-1, behave identically to H iand Hα in luminosity-line width analyses. We also examine therelation between CO line shapes and other parameters of the galaxies.
|Environments of Redshift Survey Compact Groups of Galaxies|
Redshift survey compact groups (RSCGs) are tight knots of N >= 3galaxies selected from the CfA2+SSRS2 redshift survey. The selection isbased on physical extent and association in redshift space alone. Wemeasured 300 new redshifts of fainter galaxies within 1 h^-1 Mpc of 14RSCGs to explore the relationship between RSCGs and their environments.Thirteen of 14 RSCGs are embedded in overdense regions of redshiftspace. The systems range from a loose group of five members to an Abellcluster. The remaining group, RSCG 64, appears isolated. RSCGs areisolated and distinct from their surroundings to varying degrees, as arethe Hickson compact groups. Among the 13 embedded RSCGs, three aredistinct from their general environments (RSCG 9, RSCG 11, and RSCG 85).
|Observations of (C-12)O (J = 1-0) in 44 cluster galaxies|
We present (C-12)O (J = 10) (2.6 mm, 115 GHz) spectra from 44 galaxiesin clusters between 3500 and 8000 km/s. The data were obtained using theNRAO 12 m telescope at Kitt Peak. Forty galaxies are detected. We deducemolecular gas masses from the line integrated intensities and upperlimits for the four nondetections. Although the sample's first inclusioncriterion is that a source have 60 m flux greater than 350 mJy, thegalaxies in this survey are found to be neither ultraluminous in the FIRnor particularly rich in molecular gas, nor do they exhibit evidence ofinteractions. Neither the molecular gas mass nor the far-IR luminosityshows variations as functions of the galaxies' proximity to the clustercores. Because the CO line widths and central velocities agree overallwith the 21 cm widths and redshifts for these galaxies, we argue that COspectra could be used in lieu of H I spectra for Tully-Fishercalculations.
|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.
|Homogeneous Velocity-Distance Data for Peculiar Velocity Analysis. III. The Mark III Catalog of Galaxy Peculiar Velocities|
This is the third in a series of papers in which we assemble and analyzea homogeneous catalog of peculiar velocity data. In Papers I and II, wedescribed the Tully-Fisher (TF) redshift-distance samples thatconstitute the bulk of the catalog and our methodology for obtainingmutually consistent TF calibrations for these samples. In this paper, wesupply further technical details of the treatment of the data andpresent a subset of the catalog in tabular form. The full catalog, knownas the Mark III Catalog of Galaxy Peculiar Velocities, is available inaccessible on-line databases, as described herein. The electroniccatalog incorporates not only the TF samples discussed in Papers I andII but also elliptical galaxy Dn- sigma samples originally presentedelsewhere. The relative zero pointing of the elliptical and spiral datasets is discussed here. The basic elements of the Mark III Catalog arethe observables for each object (redshift, magnitude, velocity width,etc.) and inferred distances derived from the TF or Dn- sigma relations.Distances obtained from both the forward and inverse TF relations aretabulated for the spirals. Malmquist bias--corrected distances arecomputed for each catalog object using density fields obtained from theIRAS 1.2 Jy redshift survey. Distances for both individual objects andgroups are provided. A variety of auxiliary data, including distancesand local densities predicted from the IRAS redshift surveyreconstruction method, are tabulated as well. We study the distributionsof TF residuals for three of our samples and conclude that they are wellapproximated as Gaussian. However, for the Mathewson et al. sample wedemonstrate a significant decrease in TF scatter with increasingvelocity width. We test for, but find no evidence of, a correlationbetween TF residuals and galaxy morphology. Finally, we derivetransformations that map the apparent magnitude and velocity width datafor each spiral sample onto a common system. This permits theapplication of analysis methods that assume that a unique TF relationdescribes the entire sample.
|Recovering Galaxy Rotation Speeds from Irregular Emission Profiles|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2437L&db_key=AST
|Optical Rotation Curves and Linewidths for Tully-Fisher Applications|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2402C&db_key=AST
|Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation|
I-band luminosities, rotational velocities, and redshifts of 1092 spiralgalaxies have been measured by CCD photometry and Hα spectroscopyusing the 1 m and 2.3 m telescopes at Siding Spring Observatory,respectively. The results are tabulated. Luminosity profiles andHα rotation curves are given for the galaxies. When these resultsare combined with similar data for 1355 spiral galaxies publishedpreviously (Mathewson, Ford, & Buchhorn, hereafter Paper I), itprovides a large, uniform, and unique data set with which to measure,via the Tully-Fisher relation, the peculiar velocities of galaxies inthe local universe to a distance of 11,000 km s^-1^ (Mathewson &Ford). Taking advantage of the opportunity for publishing this data inmachine-readable form, in the CD-ROM, we have also included similar datafor the 1355 galaxies in Paper I.
|Deep r-Band Photometry for Northern Spiral Galaxies|
We present r-band surface photometry for 349 northern Sb-Sc UGCgalaxies, from a total of 627 CCD images. For each galaxy, we presentsurface brightness profiles, isophotal and total magnitudes, isophotalradii, and structural parameters from exponential fits to the disk. Onehundred ninety-five galaxies have been observed more than once. Allnights with a photometric transformation scatter greater than 0.022 magwere rejected. Sky errors are investigated carefully and yield profilesthat are reliable down to 26 r mag arcsec^-2^, Deep isophotal magnitudesare as accurate as +/-0.019, and extrapolated magnitudes are internallyconsistent to within 0.020. We compare visual (UGC) and CCD isophotaldiameters and show that axial ratio must be included as a thirdparameter. Comparison with the r-band CCD photometry of Kent andWillick, and accounting for sky errors, suggest typical errors for totalmagnitudes of +/-0.08. Our data are also shown to be zero-pointed on thesame Gunn r system as that of Kent and Willick. Ellipticity measurementsagree very well except for progressively face-on galaxies where spiralstructure is more conspicuous. The ellipticity internal error is lessthan 0.02, or about 3^deg^ for inclinations. Our internal extinctioncorrection implies that disks are semitransparent in their outer parts.We caution that comparison of central surface brightnesses and scalelengths is complicated by the subjective nature of their measurement;extreme care must be applied when using such quantities. We measure anapparent Freeman law of (μ_0,c_) = 20.08 +/- 0.55 r mag arcsec^-2^.This magnitude-limited sample was originally derived for studies oflarge-scale motions in the local universe. The deep CCD photometry isalso ideally suited for matching spectroscopic studies, mass modeling,galaxy structural analysis, etc.
|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.
|Recalibration of the H-0.5 magnitudes of spiral galaxies|
The H-magnitude aperture data published by the Aaronson et al.collaboration over a 10 year period is collected into a homogeneous dataset of 1731 observations of 665 galaxies. Ninety-six percent of thesegalaxies have isophotal diameters and axial ratios determined by theThird Reference Cataloque of Bright Galaxies (RC3; de Vaucouleurs et al.1991), the most self-consistent set of optical data currently available.The precepts governing the optical data in the RC3 are systematicallydifferent from those of the Second Reference Catalogue (de Vaucouleurs,de Vaucouleurs, & Corwin 1976), which were used by Aaronson et al.for their original analyses of galaxy peculiar motions. This in turnleads to systematic differences in growth curves and fiducialH-magnitudes, prompting the present recalibration of the near-infraredTully-Fisher relationship. New optically normalized H-magnitude growthcurves are defined for galaxies of types SO to Im, from which new valuesof fiducial H-magnitudes, Hg-0.5, are measured forthe 665 galaxies. A series of internal tests show that these fourstandard growth curves are defined to an accuracy of 0.05 mag over theinterval -1.5 less than or equal to log (A/Dg) less than orequal to -0.2. Comparisons with the Aaronson et al. values of diameters,axial ratios, and fiducial H-magnitudes show the expected differences,given the different definitions of these parameters. The values ofHg-0.5 are assigned quality indices: a qualityvalue of 1 indicates an accuracy of less than 0.2 mag, quality 2indicates an accuracy of 0.2-0.35 mag, and quality 3 indicates anaccuracy of more than 0.35 mag. Revised values of corrected H I velocitywidths are also given, based on the new set of axial ratios defiend bythe RC3.
|Kinematics and dynamics of the MKW/AWM poor clusters|
We report 472 new redshifts for 416 galaxies in the regions of the 23poor clusters of galaxies originally identified by Morgan, Kayser, andWhite (MKW), and Albert, White, and Morgan (AWM). Eighteen of the poorclusters now have 10 or more available redshifts within 1.5/h Mpc of thecentral galaxy; 11 clusters have at least 20 available redshifts. Basedon the 21 clusters for which we have sufficient velocity information,the median velocity scale is 336 km/s, a factor of 2 smaller than foundfor rich clusters. Several of the poor clusters exhibit complex velocitydistributions due to the presence of nearby clumps of galaxies. We checkon the velocity of the dominant galaxy in each poor cluster relative tothe remaining cluster members. Significantly high relative velocities ofthe dominant galaxy are found in only 4 of 21 poor clusters, 3 of whichwe suspect are due to contamination of the parent velocity distribution.Several statistical tests indicate that the D/cD galaxies are at thekinematic centers of the parent poor cluster velocity distributions.Mass-to-light ratios for 13 of the 15 poor clusters for which we havethe required data are in the range 50 less than or = M/LB(0)less than or = 200 solar mass/solar luminosity. The complex nature ofthe regions surrounding many of the poor clusters suggests that thesegroupings may represent an early epoch of cluster formation. Forexample, the poor clusters MKW7 and MKWS are shown to be gravitationallybound and likely to merge to form a richer cluster within the nextseveral Gyrs. Eight of the nine other poor clusters for which simpletwo-body dynamical models can be carried out are consistent with beingbound to other clumps in their vicinity. Additional complex systems withmore than two gravitationally bound clumps are observed among the poorclusters.
|Arm structure in normal spiral galaxies, 1: Multivariate data for 492 galaxies|
Multivariate data have been collected as part of an effort to develop anew classification system for spiral galaxies, one which is notnecessarily based on subjective morphological properties. A sample of492 moderately bright northern Sa and Sc spirals was chosen for futurestatistical analysis. New observations were made at 20 and 21 cm; thelatter data are described in detail here. Infrared Astronomy Satellite(IRAS) fluxes were obtained from archival data. Finally, new estimatesof arm pattern radomness and of local environmental harshness werecompiled for most sample objects.
|A revised catalog of CfA1 galaxy groups in the Virgo/Great Attractor flow field|
A new identification of groups and clusters in the CfA1 Catalog ofHuchra et al. is presented, using a percolation algorithm to identifydensity enhancements. It is shown that in the resulting catalog,contamination by interlopers is significantly reduced. The Schechterluminosity function is redetermined, including the Malmquist bias.
|The small scale environment of low surface brightness disk galaxies|
We use a sample of about 340 low surface brightness (LSB) disk galaxieswith measured redshifts in combination with the Center for Astrophysicsredshift survey to test the hypothesis that LSB galaxies have a deficitof nearby companion galaxies compared to high surface brightness (HSB)disk galaxies. We find a very strong statistical deficit of galaxieslocated within a projected radius of 0.5 Mpc and within a velocity of500 km/s around LSB disk galaxies compared to HSB ones. Further,comparing LSB and HSB disk galaxies which are located in the sameportion of the sky indicates that the average distance to the nearestneighbor is 1.7 times farther for LSB disk galaxies. AKomologorov-Smirnoff test rules out, at greater than the 99 percentconfidence level, the hypothesis that the distribution ofnearest-neighbor distances is the same for HSB and LSB disk galaxies. Wespeculate that LSB disk galaxies have relatively long formation timescales and therefore must form in relative isolation. In addition, thelack of tidal interactions over a Hubble time serves to suppress theoverall star-formation rate as no external trigger is available to helpclump the gas. The observed low surface densities of H I in combinationwith the low probability of tidal interactions effectively preventsthese disk galaxies from evolving very rapidly.
|I-band CCD surface photometry of spiral galaxies in 16 nearby clusters|
Results of I-band CCD surface photometry for 284 spiral galaxies in 16clusters in the redshift range from 3000 to 11,000 km/s are presented.Various effects on surface photometry are discussed, and the relevantcorrections are outlined.
|The far-infrared properties of the CfA galaxy sample. I - The catalog|
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
|Isophotal diameters of cluster spirals|
The applicability of isophotal diameters for measuring the sizes ofgalaxies is examined by comparing diameters derived using surfacephotometry with those derived from the Uppsala General Catalogue ofGalaxies (UGC). The sample studied consisted of a subset of galaxiesfrom the CCD survey of Bothun (1981). The surface photometry techniqueused is described, and the surface brightness profiles were extractedfrom the data using the galaxy surface photometry package of Cawson(1983). Isophotal diameters were derived and compared with those fromthe UGC. The differences between the data are 2.4 arcsec for the galaxydiameter, 0.03 for the galaxy ellipticities, and 0.05 mag for the galaxymagnitudes; it is observed that the isophotal diameters determined bysurface photometry are more accurate than those tabulated by UGC. The21-cm line width/diameter relation and the absolute magnitude/surfacebrightness relation are analyzed using the isophotal diameter data.
|Cluster population incompleteness bias and the value of H(0) from the Tully-Fisher B0(T) relation|
Data on the Virgo cluster and ten more distant clusters are the basis ofan evaluation of the influence of the cluster population incompletenessbias on the B-band Tully-Fisher relation. The data are well fitted by atheoretical curve that is obtained for a Hubble constant value of 72 +or - 5 km/sec per Mpc in the de Vaucouleurs local scale, confirming theconstant's previous determination in light of a study of the Malmquistbias for field galaxies. The true value for the Hubble constant isconcluded to lie within the 50-75 range, depending on the primarycalibration.
|A distance scale from the infrared magnitude/H I velocity-width relations. V - Distance moduli to 10 galaxy clusters, and positive detection of bulk supercluster motion toward the microwave anisotropy|
The IR/H I relation is employed to derive relative distances to 10nearby galaxy clusters. A problem originally identified by van den Bergh(1981), that the surface brightnesses of galaxies in the higher redshiftclusters are in the mean found to be lower than in nearby clusters atfixed velocity width, is discussed. The extent to which this effect isaccounted for by galaxy diameter errors is investigated in detail.Cluster distance moduli and Hubble ratios are derived after firstconsidering a number of potential biases in the data. A variety of solarmotion solutions are obtained with respect to the reference frame of theclusters, and the value of the Hubble constant is discussed. The finalcluster Hubble ratios exhibit considerable scatter, signifying thepresence of an unaccounted for Local Group streaming motion. Formalsolution leads to a velocity in close agreement with the 3 K dipoleanisotropy.
|A catalog of radio, optical, and infrared observations of spiral galaxies in clusters|
The results of a major observational program on the luminosities,colors, and gas contents of spiral galaxies in clusters of galaxies arepresented. The data have been used as part of a detailed investigationinto the nature of cluster spirals and for revisions of the distancescale using the infrared Tully-Fisher relation. The observationalstrategies, reduction procedures, and sources or error are brieflydiscussed. The data include 21-cm H I observations, UBVR multiaperturephotometry, and H-band photometry of several hunderd spiral galaxies in10 clusters.
|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.
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