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The Molecular Interstellar Medium of Dwarf Galaxies on Kiloparsec Scales: A New Survey for CO in Northern, IRAS-detected Dwarf Galaxies
We present a new survey for CO in dwarf galaxies using the ARO Kitt Peak12 m telescope. This survey consists of observations of the centralregions of 121 northern dwarfs with IRAS detections and no known COemission. We detect CO in 28 of these galaxies and marginally detectanother 16, increasing by about 50% the number of such galaxies known tohave significant CO emission. The galaxies we detect are comparable instellar and dynamical mass to the Large Magellanic Cloud, althoughsomewhat brighter in CO and fainter in the far-IR. Within dwarfs, wefind that the CO luminosity LCO is most strongly correlatedwith the K-band and the far-infrared luminosities. There are also strongcorrelations with the radio continuum (RC) and B-band luminosities andlinear diameter. Conversely, we find that far-IR dust temperature is apoor predictor of CO emission within the dwarfs alone, although a goodpredictor of normalized CO content among a larger sample of galaxies. Wesuggest that LCO and LK correlate well because thestellar component of a galaxy dominates the midplane gravitational fieldand thus sets the pressure and density of the atomic gas, which controlthe formation of H2 from H I. We compare our sample with moremassive galaxies and find that dwarfs and large galaxies obey the samerelationship between CO and the 1.4 GHz RC surface brightness. Thisrelationship is well described by a Schmidt law withΣRC~Σ1.3CO. Therefore,dwarf galaxies and large spirals exhibit the same relationship betweenmolecular gas and star formation rate (SFR). We find that this result isrobust to moderate changes in the RC-to-SFR and CO-to-H2conversion factors. Our data appear to be inconsistent with large (orderof magnitude) variations in the CO-to-H2 conversion factor inthe star-forming molecular gas.
| Circumnuclear Structure and Black Hole Fueling: Hubble Space Telescope NICMOS Imaging of 250 Active and Normal Galaxies
Why are the nuclei of some galaxies more active than others? If mostgalaxies harbor a central massive black hole, the main difference isprobably in how well it is fueled by its surroundings. We investigatethe hypothesis that such a difference can be seen in the detailedcircumnuclear morphologies of galaxies using several quantitativelydefined features, including bars, isophotal twists, boxy and diskyisophotes, and strong nonaxisymmetric features in unsharp-masked images.These diagnostics are applied to 250 high-resolution images of galaxycenters obtained in the near-infrared with NICMOS on the Hubble SpaceTelescope. To guard against the influence of possible biases andselection effects, we have carefully matched samples of Seyfert 1,Seyfert 2, LINER, starburst, and normal galaxies in their basicproperties, taking particular care to ensure that each was observed witha similar average scale (10-15 pc pixel-1). Severalmorphological differences among our five different spectroscopicclassifications emerge from the analysis. The H II/starburst galaxiesshow the strongest deviations from smooth elliptical isophotes, whilethe normal galaxies and LINERs have the least disturbed morphology. TheSeyfert 2s have significantly more twisted isophotes than any othercategory, and the early-type Seyfert 2s are significantly more disturbedthan the early-type Seyfert 1s. The morphological differences betweenSeyfert 1s and Seyfert 2s suggest that more is at work than simply theviewing angle of the central engine. They may correspond to differentevolutionary stages.
| A Hubble Space Telescope Census of Nuclear Star Clusters in Late-Type Spiral Galaxies. II. Cluster Sizes and Structural Parameter Correlations
We investigate the structural properties of nuclear star clusters inlate-type spiral galaxies. More specifically, we fit analytical modelsto Hubble Space Telescope images of 39 nuclear clusters in order todetermine their effective radii after correction for the instrumentalpoint-spread function. We use the results of this analysis to comparethe luminosities and sizes of nuclear star clusters to those of otherellipsoidal stellar systems, in particular the Milky Way globularclusters. Our nuclear clusters have a median effective radius ofre=3.5 pc, with 50% of the sample falling in the range2.4pc<=re<=5.0pc. This narrow size distribution isstatistically indistinguishable from that of Galactic globular clusters,even though the nuclear clusters are, on average, 4 mag brighter thanthe old globular clusters. We discuss some possible interpretations ofthis result. From a comparison of nuclear cluster luminosities withvarious properties of their host galaxies, we confirm that more luminousgalaxies harbor more luminous nuclear clusters. It remains unclearwhether this correlation mainly reflects the influence of galaxy size,mass, and/or star formation rate. Since the brighter galaxies in oursample typically have stellar disks with a higher central surfacebrightness, nuclear cluster luminosity also correlates with thisproperty of their hosts. On the other hand, we find no evidence for acorrelation between the presence of a nuclear star cluster and thepresence of a large-scale stellar bar.
| The Hα galaxy survey. I. The galaxy sample, Hα narrow-band observations and star formation parameters for 334 galaxies
We discuss the selection and observations of a large sample of nearbygalaxies, which we are using to quantify the star formation activity inthe local Universe. The sample consists of 334 galaxies across allHubble types from S0/a to Im and with recession velocities of between 0and 3000 km s-1. The basic data for each galaxy are narrowband H\alpha +[NII] and R-band imaging, from which we derive starformation rates, H\alpha +[NII] equivalent widths and surfacebrightnesses, and R-band total magnitudes. A strong correlation is foundbetween total star formation rate and Hubble type, with the strongeststar formation in isolated galaxies occurring in Sc and Sbc types. Moresurprisingly, no significant trend is found between H\alpha +[NII]equivalent width and galaxy R-band luminosity. More detailed analyses ofthe data set presented here will be described in subsequent papers.Based on observations made with the Jacobus Kapteyn Telescope operatedon the island of La Palma by the Isaac Newton Group in the SpanishObservatorio del Roque de los Muchachos of the Instituto deAstrofísica de Canarias.The full version of Table \ref{tab3} is available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/414/23 Reduced image datafor this survey can be downloaded fromhttp://www.astro.livjm.ac.uk/HaGS/
| Molecular gas in the central regions of the latest-type spiral galaxies
Using the IRAM 30 >m telescope, we have surveyed an unbiased sampleof 47 nearby spiral galaxies of very late (Scd-Sm) Hubble-type foremission in the 12CO(1-0) and (2-1) lines. The sensitivity ofour data (a few mK) allows detection of about 60% of our sample in atleast one of the CO lines. The median detected H2 mass is1.4x 107 >msun within the central few kpc, assuming astandard conversion factor. We use the measured line intensities tocomplement existing studies of the molecular gas content of spiralgalaxies as a function of Hubble-type and to significantly improve thestatistical significance of such studies at the late end of the spiralsequence. We find that the latest-type spirals closely follow thecorrelation between molecular gas content and galaxy luminosityestablished for earlier Hubble types. The molecular gas in late-typegalaxies seems to be less centrally concentrated than in earlier types.We use Hubble Space Telescope optical images to correlate the moleculargas mass to the properties of the central galaxy disk and the compactstar cluster that occupies the nucleus of most late-type spirals. Thereis no clear correlation between the luminosity of the nuclear starcluster and the molecular gas mass, although the CO detection rate ishighest for the brightest clusters. It appears that the central surfacebrightness of the stellar disk is an important parameter for the amountof molecular gas at the galaxy center. Whether stellar bars play acritical role for the gas dynamics remains unclear, in part because ofuncertainties in the morphological classifications of our sample.
| Bar Galaxies and Their Environments
The prints of the Palomar Sky Survey, luminosity classifications, andradial velocities were used to assign all northern Shapley-Ames galaxiesto either (1) field, (2) group, or (3) cluster environments. Thisinformation for 930 galaxies shows no evidence for a dependence of barfrequency on galaxy environment. This suggests that the formation of abar in a disk galaxy is mainly determined by the properties of theparent galaxy, rather than by the characteristics of its environment.
| A Hubble Space Telescope Census of Nuclear Star Clusters in Late-Type Spiral Galaxies. I. Observations and Image Analysis
We present new Hubble Space Telescope I-band images of a sample of 77nearby late-type spiral galaxies with low inclination. The main purposeof this catalog is to study the frequency and properties of nuclear starclusters. In 59 galaxies of our sample, we have identified a distinct,compact (but resolved), and dominant source at or very close to thephotocenter. In many cases, these clusters are the only prominent sourcewithin a few kiloparsecs from the galaxy nucleus. We present surfacebrightness profiles, derived from elliptical isophote fits, of allgalaxies for which the fit was successful. We use the fitted isophotesat radii larger than 2" to check whether the location of the clustercoincides with the photocenter of the galaxy and confirm that in nearlyall cases, we are truly dealing with ``nuclear'' star clusters. Fromanalytical fits to the surface brightness profiles, we derive thecluster luminosities after subtraction of the light contribution fromthe underlying galaxy disk and/or bulge. Based on observations made withthe NASA/ESA Hubble Space Telescope, obtained at the Space TelescopeScience Institute, which is operated by the Association of Universitiesfor Research in Astronomy, Inc., under NASA contract NAS 5-26555. Theseobservations are associated with proposal 8599.
| Statistical Properties of Circumnuclear H II Regions in Nearby Galaxies
We analyze the statistical properties of the circumnuclear H II regionsof a sample of 52 nearby galaxies (v<1000 km s-1) fromarchival HST/NICMOS H-band and Paα (1.87 μm) observations atunprecedented spatial resolutions of between 1 and 30 pc. We catalog HII regions from the continuum-subtracted Paα images and find H IIregions in the central regions of most galaxies, and more than a hundredin each of eight galaxies. In contrast to disk H II regions, thephysical properties (luminosity and size) of individual circumnuclear HII regions do not vary strongly with the morphological type of the hostgalaxy, nor does the number of circumnuclear H II regions per unit area.The Hα luminosity within the central kiloparsec, as derived from HII region emission, is significantly enhanced in early-type (S0/a-Sb)galaxies. We find evidence that bars increase the circumnuclear starformation, presumably by funneling gas from the disk toward the nucleus.Barred galaxies exhibit enhanced luminosities of the brightest H IIregion, the central kiloparsec Hα luminosities (an effect mostlydue to the early-type galaxies in our sample), and the star formationrates per unit stellar mass (which could also be understood as theintegral equivalent widths of Paα) over the central kiloparsecwith respect to nonbarred galaxies. We fit the luminosity functions(LFs) and diameter distributions of the circumnuclear H II regions ineight galaxies where we can catalog enough H II regions to do so in ameaningful way. We use power laws and find that the fitted slopes of theH II region LF are exactly in the previously found ranges and evenconfirm a trend with steeper slopes in galaxies of earlier morphologicaltype. This implies that the physical processes giving rise to enhancedstar formation in the circumnuclear regions of galaxies must be similarto those in disks. Based on observations with the NASA/ESA Hubble SpaceTelescope, obtained from the data archive at the Space Telescope ScienceInstitute, which is operated by the Association of Universities forResearch in Astronomy, Inc., under NASA contract NAS 5-26555.
| 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.
| The NICMOS Snapshot Survey of Nearby Galaxies
We present ``snapshot'' observations with the Near-Infrared Camera andMulti-Object Spectrometer (NICMOS) on board the Hubble Space Telescope(HST) of 94 nearby galaxies from the Revised Shapley Ames Catalog.Images with 0.2" resolution were obtained in two filters, a broadbandcontinuum filter (F160W, roughly equivalent to the H band) and anarrowband filter centered on the Paα line (F187N or F190N,depending on the galaxy redshift) with the 51^''x51^'' field of view ofthe NICMOS camera 3. A first-order continuum subtraction is performed,and the resulting line maps and integrated Paα line fluxes arepresented. A statistical analysis indicates that the average Paαsurface brightness in the central regions is highest in early-type(Sa-Sb) spirals.
| 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).
| Internal extinction, population incompleteness bias and the faint-end of the B-band Tully-Fisher relation
We analyse the distribution of three different samples of spiralgalaxies of the Local Universe in the B-band luminosity-maximumrotational velocity (L_B-VMax) plane, i.e. the B-magnitudeTully-Fisher (TF) relation. The first sample comprises 25+31 late-type(from Sa to Im-BCD) galaxies, selected from, respectively, the Virgo andthe Ursa Major clusters. In addition, a sample of 20 group extremelate-type (ELT) spiral (from Sd to Sm) galaxies and a sample of 13 dwarflate-type galaxies are selected. First, we analyse the influence ofthree different corrections for internal extinction (IE) on both theslope and the zero-point of the relation. These recipes reflect eitheri) the morphological type dependence of the IE or ii) the assumption ofa ``sandwich-model'' for the distribution of the dust and the stellarcomponents within the disk or iii) the existence of the metallicity-massrelation. As a first result we find that the latter recipe of IEcorrection systematically makes Sa-Sc galaxies brighter than laterspirals. Since the former galaxies mainly populate the region of thebright, fast rotators, the slope of the corresponding TF relationbecomes much steeper than in the other two cases. Under the hypothesisthat the ELT spiral galaxies in clusters and in groups share the sameLF, we show that the claimed skew of the group ELT spiral galaxies withrespect to the extrapolated TF relation of more luminous systems (i.e.the local TF calibrators) is due both to the population incompletenessbias affecting such a template and to the type segregation. Finally, weconfirm that the distribution of dwarf galaxies with comparablerotational and random velocities in the L_B-VMax plane isconsistent with the relation of more luminous systems, while therotationally supported dwarf galaxies are underluminous with respect tothe ELT galaxies of the same VMax. However, the latterresults may suffer from the heterogeneous methods of measurement ofdwarf galaxy distances that were adopted.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| 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.
| Influence of a partial incompleteness of the sample on the determination of the Hubble constant.
This paper presents a study of the Malmquist bias effect in thedetermination of the Hubble constant from the method of "sosies"(look-alike) galaxies. It is shown that a bias appears when a partialincompleteness exists in the sample. A new method, based on the use ofthe completeness curve, is proposed to correct for such a bias. Afterthis correction, the Hubble constant drops of about 20% just because ofthe existence of the partial incompleteness. From the present resultsand on the acceptance of the distance modulus of primary calibrators,the value of the Hubble constant would be: H_0_=~60km/s/Mpc with aninternal statistical error of about 2km/s/Mpc.
| The Ursa Major Cluster of Galaxies.I.Cluster Definition and Photometric Data
The Ursa Major Cluster has received remarkably little attention,although it is as near as the Virgo Cluster and contains a comparablenumber of H I-rich galaxies. In this paper, criteria for groupmembership are discussed and data are presented for 79 galaxiesidentified with the group. Of these, all 79 have been imaged at B,R,Ibands with CCDs, 70 have been imaged at K' with a HgCdTe array detector,and 70 have been detected in the HI 21 cm line. A complete sample of 62galaxies brighter than M_B_ = - 16.5 is identified. Images and gradientsin surface brightness and color are presented at a common linear scale.As has been seen previously, the galaxies with the reddest global colorsare reddest at the centers and get bluer at large radii. However,curiously, among the galaxies with the bluest global colors there aresystems with very blue cores that get redder at large radii.
| 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.
| Testing Models for the Quasar Big Blue Bump via Color-Color Diagrams
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...454...77S&db_key=AST
| The orientation of spin vectors of galaxies in the Ursa Major filament
Spin vectors of 60 galaxies in the 'Ursa Major filament' are obtainedfrom CCD images and spectroscopic determinations of the directions ofrotation. These data are used to remove the fourfold degeneracyintroduced by the projected images of galaxies, making possible thecomplete reconstruction of the galaxy spin vectors. Several possibleorganizations of spin vectors are investigated by means of statisticalanalyses of the three-dimensional spin vector maps. The results indicatethat there exists no significant alignment of galaxy spin vectors withrespect to the supergalactic plane, the supergalactic axis, or thecylindrical axis of the filament itself. No tendency for linearalignment of spin vectors toward any specific direction was detected. Wealso obtain a statistically negative result for azimuthal, radial, andcircular-helical orientation of spin vectors.
| A Preliminary Classification Scheme for the Central Regions of Late-Type Galaxies
The large-scale prints in The Carnegie Atlas of Galaxies have been usedto formulate a classification scheme for the central regions oflate-type galaxies. Systems that exhibit small bright central bulges ordisks (type CB) are found to be of earlier Hubble type and of higherluminosity than galaxies that do not contain nuclei (type NN). Galaxiescontaining nuclear bars, or exhibiting central regions that are resolvedinto individual stars and knots, and galaxies with semistellar nuclei,are seen to have characteristics that are intermediate between those oftypes CB and NN. The presence or absence of a nucleus appears to be auseful criterion for distinguishing between spiral galaxies andmagellanic irregulars.
| The UV properties of normal galaxies. III. Standard luminosity profiles and total magnitudes.
In the previous papers of this series we collected and reduced to thesame system all the available photometric data obtained in theultraviolet (UV) range for normal (i.e. non active) galaxies. Here weuse these data to derive standard UV luminosity profiles for threemorphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated totalmagnitudes for almost 400 galaxies. We find that: 1) the UV growthcurves are well matched by the B-band revised standard luminosityprofiles, once a proper shift in the effective radius is applied, and 2)the UV light in early-type galaxies is more centrally concentrated thanthe visible light.
| The UV properties of normal galaxies. II. The ``non-IUE'' data.
In the last decade several satellite and balloon borne experiments havecollected a large number of ultraviolet fluxes of normal galaxiesmeasured through apertures of various sizes and shapes. We havehomogenized this data set by deriving scale corrections with respect toIUE. In a forthcoming paper these data will be used to derive standardluminosity profiles and total magnitudes.
| 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 Infrared Tully-Fisher Relation in the Ursa Major Cluster
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993ApJ...418..626P&db_key=AST
| IRAS CPC Observations of Galaxies - Part One - Catalog and Atlas
. - We present the results of far-infrared imaging observations of 258regions of 12' x9' each centered on a selected individual galaxy, aclose pair, or a compact group of galaxies mapped at 50 and 100 micronwavelength with the CPC instrument of the IRAS satellite. The CPCinstrument has a significantly better resolution than the IRAS Surveyinstrument at these wavelengths, i.e. a round beam with a FWHM of about80" at 50 microns and 95" at 100 microns, respectively, intended to bematched to the diffraction limit of the telescope at 100 microns. Themaps were made using a new algorithm to correct for gain variations,which gives better results than the one used previously for the imagesmade available on tape in 1985. Of 262 objects observed, 167 and 188were detected at 50 and 100 microns, respectively, about 85% of thegalaxies from the same sample listed as detected by the Surveyinstrument in the IRAS Point Source Catalog. For all 55 galaxiesresolved (i.e. with a FWHM major axis diameter exceeding 1.6 times thebeam FWHM and/or extended lower-level emission) by the CPC we alsopresent the averaged maps at 50 and 100 microns. These 55 objectsinclude 35 for which there are no published maps obtained with the IRASSurvey instrument. We rescaled the flux densities of the published CPCmaps using the more accurate IRAS Survey instrument data, since theabsolute flux density calibration of the CPC is only accurate to about+/-60%. We also present images of a triplet of galaxies associated witha single Survey point source, which were resolved into separate sourcesby the CPC.
| 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.
| 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.
| The joint far-infrared-optical luminosity function for spiral galaxies and data for the Abell 400 and Cancer clusters
Visual and IRAS data for an optically selected sample of 183 late-typegalaxies are compiled in tables and graphs and analyzed in detail todetermine the joint FIR-optical luminosity function Psi from theFIR/blue luminosity ratio, r = L(FIR)/L(B). It is found that Psi can beapproximated by a function of a single variable psi(r-prime), wherer-prime is defined as r times L(B)/L(asterisk) exp -delta, withL(asterisk) a constant and delta = about 0.08. A lognormal curve peakingat r-prime = 0.35 and with dispersion of 0.28 is shown to give a goodfit to psi(r-prime). From a lack of galaxies with very low r-prime inthe present sample it is inferred that there are few spiral galaxieswith low interstellar-dust abundances. Also included are data on thedistribution function of r-prime for the more distant clusters Abell 400and Cancer.
| The Tully-Fisher relation in different environments
The Tully-Fisher relation (TFR) in different environments wasinvestigated in 13 galaxy samples spanning a large range in galaxydensities, using two statistical tests to compare the TFR of differentsamples. Results of the analysis of TFR parameters in severalenvironments showed that, when samples of similar data-accuracy andmagnitude-range were compared, there was no significant differencebetween the galaxy samples. It is suggested that a comparison of sampleswith very different data accuracy or those biased by incompletenesseffects may lead to misleading results.
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