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A search for Low Surface Brightness galaxies in the near-infrared. I. Selection of the sample
A sample of about 3800 Low Surface Brightness (LSB) galaxies wasselected using the all-sky near-infrared (J, H and Ks-band)2MASS survey. The selected objects have a mean central surfacebrightness within a 5'' radius around their centre fainter than 18 magarcsec-2 in the Ks band, making them the lowestsurface brightness galaxies detected by 2MASS. A description is given ofthe relevant properties of the 2MASS survey and the LSB galaxy selectionprocedure, as well as of basic photometric properties of the selectedobjects. The latter properties are compared to those of other samples ofgalaxies, of both LSBs and ``classical'' high surface brightness (HSB)objects, which were selected in the optical. The 2MASS LSBs have aBT_c-KT colour which is on average 0.9 mag bluerthan that of HSBs from the NGC. The 2MASS sample does not appear tocontain a significant population of red objects.All tables and Figs. 2a-c are only available in electronic form athttp://www.edpsciences.org
| 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
| Classifications of the Host Galaxies of Supernovae
Classifications on the DDO system are given for the host galaxies of 177supernovae (SNe) that have been discovered since 1997 during the courseof the Lick Observatory Supernova Search with the Katzman AutomaticImaging Telescope. Whereas SNe Ia occur in all galaxy types, it isfound, at a high level of statistical confidence, that SNe Ib, Ic, andII are strongly concentrated in late-type galaxies. However, attentionis drawn to a possible exception provided by SN 2001I. This SN IInoccurred in the E2 galaxy UGC 2836, which was not expected to harbor amassive young supernova progenitor.
| Rotation curves and metallicity gradients from HII regions in spiral galaxies
In this paper we study long slit spectra in the region of Hαemission line of a sample of 111 spiral galaxies with recognizable andwell defined spiral morphology and with a well determined environmentalstatus, ranging from isolation to non-disruptive interaction withsatellites or companions. The form and properties of the rotation curvesare considered as a function of the isolation degree, morphological typeand luminosity. The line ratios are used to estimate the metallicity ofall the detected HII regions, thus producing a composite metallicityprofile for different types of spirals. We have found that isolatedgalaxies tend to be of later types and lower luminosity than theinteracting galaxies. The outer parts of the rotation curves of isolatedgalaxies tend to be flatter than in interacting galaxies, but they showsimilar relations between global parameters. The scatter of theTully-Fisher relation defined by isolated galaxies is significantlylower than that of interacting galaxies. The [NII]/Hα ratios, usedas a metallicity indicator, show a clear trend between Z andmorphological type, t, with earlier spirals showing higher ratios; thistrend is tighter when instead of t the gradient of the inner rotationcurve, G, is used; no trend is found with the change in interactionstatus. The Z-gradient of the disks depends on the type, being almostflat for early spirals, and increasing for later types. The[NII]/Hα ratios measured for disk HII regions of interactinggalaxies are higher than for normal/isolated objects, even if all thegalaxy families present similar distributions of Hα EquivalentWidth. Tables 3 and 4 and Figs. 6, 7 and 21 are only available inelectronic form at http://www.edpsciences.org. Table 5 is only availablein electronic form at the 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/393/389 Based on dataobtained Asiago/Ekar Observatory. Also based on observations made withINT operated on the island of La Palma by ING in the SpanishObservatorio del Roque de Los Muchachos of the Instituto deAstrofísica de Canarias.
| 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 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.
| Nançay ``blind'' 21 CM line survey of the Canes Venatici group region
A radio spectroscopic driftscan survey in the 21 cm line with theNançay decimetric radio telescope of 0.08 steradians of sky inthe direction of the constellation Canes Venatici covering aheliocentric velocity range of -350 < V_hel < 2350 km s(-1)produced 53 spectral features, which was further reduced to a sample of33 reliably detected galaxies by extensive follow-up observations. Witha typical noise level of rms = 10 mJy after Hanning smoothing, thesurvey is - depending on where the detections are located with regard tothe centre of the beam - sensitive to M_HI = 1-2x10(8) {h}(-2) {M_sun}at 23 {h}(-1) Mpc and to M_HI = 4-8x10(7) {h}(-2) {M_sun} throughout theCVn groups. The survey region had been previously examined on deepoptical plates by \cite[Binggeli et al. (1990)]{bin90} and containsloose groups with many gas-rich galaxies as well as voids. No galaxiesthat had not been previously identified in these deep optical surveyswere uncovered in our H{sigma c i} survey, neither in the groups nor thevoids. The implication is that no substantial quantity of neutralhydrogen contained in gas-rich galaxies has been missed in thesewell-studied groups. All late-type members of our sample are listed inthe \cite[Fisher & Tully (1981b)]{fis81b} optically selected sampleof nearby late-type galaxies; the only system not contained in Fisherand Tully's Catalog is the S0 galaxy NGC 4203. Within the well-sampledCVn group volume with distances corrected for flow motions, the H {sigmac i} mass function is best fitted with the \cite[Zwaan et al.(1997)]{zwa97} H{sigma c i} mass function (alpha =-1.2) scaled by afactor of f=4.5 in account of the locally overdense region.
| Effects of interaction on the properties of spiral galaxies. II. Isolated galaxies: The zero point
We analyse the properties of a sample of 22 bright isolated spiralgalaxies on the basis of Johnson B,V,I images and optical rotationcurves. The fraction of early morphological types in our sample ofisolated galaxies (or in other samples of non-interacting spiralgalaxies) appears to be smaller than in samples including interactingsystems. The overall morphological aspect is regular and symmetric, butall the galaxies present non-axisymmetric components in the form of barsor rings. We find that the color indices become bluer towards the outerparts and that their central values are well correlated with the totalcolors. The properties of the bulges span a larger range than those ofthe disks, that thus are more alike between them. None of the galaxiesshows a truncated, type II disk profile. It is found that the relationbetween surface brightness and size for the bulges, the Kormendyrelation, is tighter when only isolated galaxies are considered. We finda similar relation for the disk parameters with an unprecedented lowscatter. A Principal Component Analysis of the measured parameters showsthat 2 eigenvectors suffice to explain more than 95 % of the totalvariance. These are, as found for other samples including spiralgalaxies in different environmental situations, a scale parameter givenby the mass or, equivalently, the luminosity or the size; and a formparameter given by the bulge to disk luminosity ratio, B/D, or,equivalently, by the gradient of the solid-body rotation region of therotation curve, the G-parameter. We report here a tight correlationbetween G and B/D for our sample of isolated spirals that could be usedas a new distance indicator. Based on data obtained at the 1.5mtelescope of the Estacion de Observacion de Calar Alto, InstitutoGeografico Nacional, which is jointly operated by the InstitutoGeografico Nacional and the Consejo Superior de InvestigacionesCientificas through the Instituto de Astrofisica de Andalucia
| Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com
| A catalogue of spatially resolved kinematics of galaxies: Bibliography
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| The Absence of X-Ray Flashes from Nearby Galaxies and the Gamma-Ray Burst Distance Scale
If typical gamma-ray bursts (GRBs) have X-ray counterparts similar tothose detected by Ginga, then sensitive-focusing X-ray telescopes willbe able to detect GRBs 3 orders of magnitude fainter than the detectionlimit of the Burst and Transient Source Experiment (BATSE). If asubstantial portion of the burst population detected by BATSE originatesin a Galactic halo at distances greater than or equal to 150 kpc,existing X-ray telescopes will be able to detect GRBs in externalgalaxies out to a distance of at least 4.5 Mpc. As reported in Gotthelf,Hamilton, & Helfand, the imaging proportional counter (IPC) on boardthe Einstein Observatory detected 42 transient events with pointlikespatial characteristics and timescales of less than 10 s. These eventsare distributed isotropically on the sky; in particular, they are notconcentrated in the directions of nearby external galaxies. For halomodels of the BATSE bursts with radii of 150 kpc or greater, we wouldexpect to see several burst events in observations pointed toward nearbygalaxies. We see none. We therefore conclude that if the Gingadetections are representative of the population of GRBs sampled byBATSE, GRBs cannot originate in a Galactic halo population with limitingradii between 150 and 400 kpc. Inasmuch as halos with limiting radiioutside of this range have been excluded by the BATSE isotropymeasurements, our result indicates that all halo models are excluded.This result is independent of whether the flashes we do detect have anastronomical origin.
| Effects of the interaction on the properties of spiral galaxies. I. The data.
We have obtained Johnson B V I images and long slit spectra along themajor axis of a sample of isolated spiral galaxies, and a sample ofspirals in isolated pairs. We present in this contribution thephotometric parameters (galactic orientation in the sky, totalmagnitudes and colors, color gradients, isophotal profiles and theirdecomposition in bulge and disk components) and the rotation curves ofthe observed galaxies. For some of the galaxies Hα images and/orspectra along the minor axis are also available and the data alsopresented here. The data we obtain are then compared with those reportedin the RC3 catalogue. The analysis of both samples and their comparisonwill be published separately.
| 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.
| Global H I profiles of spiral galaxies.
In this paper we present short H I synthesis observations of 57 galaxieswithout H I information in the RC3. These are a by-product of a largesurvey with the WSRT of the neutral hydrogen gas in spiral and irregulargalaxies. Global profiles and related quantities are given for the 42detected galaxies and upper limits for the remaining 15. A number ofgalaxies have low values of H I mass-to-blue luminosity ratio.
| Statistical correlations between basic parameters of disk galaxies
Statistical relationships between principal galaxy parameters andsurface densities of these parameters are analyzed for a sample of 63disk galaxies. These parameters include the radius, the mass of theentire galaxy and its various components (H2, HI, total gas, dust,etc.), and blue and FIR luminosity. Of all possible two- andthree-parameter linear relations between the galaxy parameterlogarithms, we choose those that have high correlation coefficients andproceed to derive their coefficients. Some of these relations arecompared with the corresponding predictions of the single-zone model ofthe disk galaxy evolution. Other relations are considered from theviewpoint of interstellar medium properties in galaxies. We find thetheory to agree satisfactorily with observations and suggest ways ofimproving evolutionary models. The method of linear orthogonalregression used in the statistical analysis is described.
| Galaxy Properties at the North Galactic Pole. I. Photometric Properties on Large Spatial Scales
A two-color study of the galaxies detected on POSS-I in a 289 squaredegree region centered on the North Galactic Pole is presented. We use avariety of mapping techniques to characterize the large-scale spatialdistribution of galaxies. The depth and sample size of this new surveyallows, for the first time, the isolation of large photometricsubsamples of galaxies in high- and low-density environments on thescale of superclusters. Our principal finding is a statisticallysignificant difference between the mean photometric properties of thesesubsamples in the sense that galaxies in the high-density Coma andfilament environments have redder colors and larger concentrationindices than galaxies drawn from low-density interfilament regions.These results are in accord with the known morphology-density relation.Thus, appropriately chosen photometric and morphological parameters, inconcert with a galaxy surface density map, can be used to selectstructures from the projected galaxy distribution which correspond toregions of high density. An illustration of this point is our discoveryof a concentration of blue galaxies identified in our maps near the coreof the Coma cluster. This feature is comprised of early-type galaxieswhich exhibit signs of current or recent star formation. These resultsare predicated on relations between morphological type and photometricparameters derived from APS scans of POSS-I. We therefore discuss theimage calibration procedures used to compile our catalog of physicallysignificant photometric parameters. We demonstrate the morphologicaltype dependence among quantities such as mean color and imageconcentration index, and the lack of such a dependence for mean surfacebrightness.
| 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.
| H I deficiency in the Coma I cloud of galaxies
We present new H I observations of galaxies in the Coma I group. Of the32 most probable members of the group, 16 are gas poor and 16 havenormal H I contents. The 16 gas poor galaxies include 4 ellipticals, 5S0s, and 7 spirals with a definite H I deficiency (more than a factor offour). Most of the 16 gas poor or H I deficient galaxies areconcentrated within a radius of 500 kpc of a centroid near the galaxyNGC 4274, suggesting that this region contains a compact core ofintergalactic matter that has stripped the gas from some of thegalaxies. Seven gas poor galaxies are even within a projected radius of130 kpc of this position. This possible existence of a dense core ofintragroup gas may explain the large H I deficiency in the barred spiralNGC 4314. which has 100 times less H I mass than would be expected fromits luminosity and stellar mass. In this galaxy the gas is 99%molecular, 1% atomic and nearly all in the central region. We suspectthe extreme H I deficiency in NGC 4314 is due to two distinct causes:ram pressure stripping of the gas in its outer parts, plus action of itsbar or an ancient tidal interaction with another galaxy that transferredgas from the inner parts of NGC 4314 to the center where H I wasconverted to H_2_.
| Molecular gas in nearby galaxies. II - The data
The study reports observations of (C-12)O J = 1-0 emission from 50nearby spiral galaxies. This is part of a distance-limited survey ofnearby systems which are not strongly interacting with their neighbors.The observations were performed during December 1988 and March 1990using the NRAO 12-m telescope at Kitt Peak with the 3-mm SIS receiversand the 256-channel x 2-MHz spectrometers.
| 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 Rate of Supernovae - Part Two - the Selection Effects and the Frequencies Per Unit Blue Luminosity
We present new estimates of the observed rates of SNe determined withthe control time method applied to the files of observations of two longterm, photographic SN searches carried out at the Asiago and SternbergObservatories. Our calculations are applied to a galaxy sample extractedfrom RC3, in which 65 SNe have been discovered. This relatively largenumber of SNe has been redistributed in the different morphologicalclasses of host galaxies giving the respective SN rates. The magnitudeof two biases, the overexposure of the central part of galaxies and theinclination of the spiral parent galaxies, have been estimated. We showthat due to overexposure an increasing fraction of SNe is lost ingalaxies of increasing distances. Also, a reduced number of SNe isdiscovered in inclined galaxies (i > 30^deg^): SN II and Ib are moreaffected than Ia, as well as SNe in Sbc-Sd galaxies with respect toother spirals. We strengthen previous findings that the SN rates isproportional to the galaxy blue luminosity for all SN and Hubble types.Other sources of errors, besides those due to the statistics of theevents, have been investigated. In particular those related to theadopted SN parameters (Cappellaro et al. 1993) and correction factor foroverexposure and inclination. Moreover we show that the frequencies ofSNe per unit luminosity vary if different sources for the parameters ofthe sample galaxies are adopted, thus hampering the comparison of SNrates based on different galaxy samples. The overall rates per unit blueluminosity are similar to the previous determinations but significantdifferences show up for individual types. In particular, the rate inellipticals, O.11 SNu (H=75 km s^-1^Mpc^-1^), is significantly lowerthan previously reported and better agrees with the predictions ofgalaxy evolutionary models. Contrary to recent claims, in late spiralsthe rates of SNIa (0.39 SNu) and Ib (0.27 SNu) are similar. The mostfrequent SNe in spiral galaxies are SNII (1.48 SNu). Even the possibleoccurrence of faint SNe similar to SN 1987A (< 0.5 SNu in latespirals) does not significantly alter the total rate of SN II. In theGalaxy, the expected number of SNe is 1.7+/-0.9 per century.
| Molecular Gas in Nearby Galaxies - Part One - Co/ Observations of a Distance-Limited Sample
This paper presents a discussion of ^12^CO J = 1 - 0 observations of adistance-limited sample of nearby spiral galaxies. The sample is biasedtowards high inclination galaxies at the lowest blue luminosities,suggesting a systematic effect. Two possible explanations are brieflydiscussed. The bias may be an artifact of the way Hubble types areassigned to galaxies or axis ratios measured, or it may indicate ameasurable effect of the local supercluster on lower mass galaxies. Themolecular mass is a relatively constant fraction (~2%) of the dynamicalmass within the region containing H_2_, but varies when the totaldynamical mass is considered (assuming a constant CO to H_2_ conversionfactor for all galaxies in the sample). The ratio of M(H_2_)/M_dyn_ isindependent of Hubble type. M(H_2_)/M(HI) is a strong function of Hubbletype, but this arises entirely because of the dependence of atomic masson type. The molecular masses and FIR luminosities are well correlated,but the average ratio of L_FIR_ to M(H_2_) is only ~1/2 that of previousstudies, which were based on (primarily) FIR selected samples. Thissuggests that the efficiency of star formation in a normal spiral galaxyis lower than that estimated by previous studies.
| Far-infrared luminosity functions of normal galaxies
A volume-limited sample is constructed from the Zwicky catalog and IRASdata base to examine the FIR luminosity functions of normal galaxies,and to investigate possible relationships between FIR emission andgalaxy morphology. Quantitative and unbiased treatment is provided by'survival analysis' statistical methods. It is found that the FIRdistributions of normal galaxies are better fit by lognormal thanSchechter functions. The total FIR emissivity (8 to 115 microns) ofnormal galaxies is approximately equal to half their emission in the Bplus V optical bands. Normal galaxy FIR emission is uncorrelated withthe basic S0-Sm Hubble sequence of spiral galaxy morphology, but appearsto be affected by de Vaucouleurs' (1959) revised morphologicalclassifications based on inner rings and S-shaped arms. Spirals withbars and inner rings are systematically fainter than unbarred spirals.It is suggested that bars and rings reduce the amount or spatiallyconfine the dust in spiral disks, resulting in lower efficiencyconversion of optical and UV photons into the IR.
| 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.
| Observations of galaxies in groups at 102 MHz
Observations of 325 galaxies in groups were carried out at a frequencyof 102 MHz via the scintillation method. Radio emission was found in 42of these components. Eleven of these have a meridional component.
| Arm classifications for spiral galaxies
The spiral arm classes of 762 galaxies are tabulated; 636 galaxies withlow inclinations and radii larger than 1 arcmin were classified on thebasis of their blue images on the Palomar Observatory Sky Survey (POSS),76 SA galaxies in the group catalog of Geller and Huchra were alsoclassified from the POSS, and 253 galaxies in high-resolution atlaseswere classified from their atlas photographs. This spiral armclassification system was previously shown to correlate with thepresence of density waves, and galaxies with such waves were shown tooccur primarily in the densest galactic groups. The present sampleindicates, in addition, that grand design galaxies (i.e., those whichtend to contain prominent density wave modes) are physically larger thanflocculent galaxies (which do not contain such prominent modes) by afactor of about 1.5. A larger group sample confirms the previous resultthat grand design galaxies are preferentially in dense groups.
| Ultraviolet observations and star-formation rate in galaxies
The present 149 galaxies, essentially of spiral and irregular types wereobserved at about 2000 A in a survey using a balloon-borne imagingtelescope. Total ultraviolet fluxes in an about 125-A wide bandpass havebeen obtained by comparison with field stars. On average, the m(2000)-Bcolor gets redder from late to early morphological types. For a giventype, this color exhibits a large scatter which increases from late toearly types. As expected, the galaxies show a relation between them(2000)-B and B-V colors. After a correction for dust extinction basedon the neutral hydrogen content of each galaxy, the observed fluxes areused to obtain quantitative estimates of the current star formation rate(SFR). A good correlation is found between the SFR and the total gascontent. A weak correlation observed between the SFR per unit area andthe average gas surface density might be compatible with the existenceof a power-law relation of exponent 1, between birthrate and gasdensity. The SFR per unit gas mass shows both a significant dispersionand a decrease toward later types. Implications in terms of starformation history are discussed.
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