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מאמרים קשורים
Objective Classification of Spiral Galaxies Having Extended Rotation Curves Beyond the Optical Radius
We carry out an objective classification of four samples of spiralgalaxies having extended rotation curves beyond the optical radius. Amultivariate statistical analysis (viz., principal component analysis[PCA]) shows that about 96% of the total variation is due to twocomponents, one being the combination of absolute blue magnitude andmaximum rotational velocity beyond the optical region and the otherbeing the central density of the halo. On the basis of PCA a fundamentalplane has been constructed that reduces the scatter in the Tully-Fisherrelation up to a maximum of 16%. A multiple stepwise regression analysisof the variation of the overall shape of the rotation curves shows thatit is mainly determined by the central surface brightness, while theshape purely in the outer part of the galaxy (beyond the optical radius)is mainly determined by the size of the galactic disk.
| [O II] as a Star Formation Rate Indicator
We investigate the [O II] emission line as a star formation rate (SFR)indicator using integrated spectra of 97 galaxies from the Nearby FieldGalaxies Survey (NFGS). The sample includes all Hubble types andcontains SFRs ranging from 0.01 to 100 Msolaryr-1. We compare the Kennicutt [O II] and Hα SFRcalibrations and show that there are two significant effects thatproduce disagreement between SFR([O II]) and SFR(Hα): reddeningand metallicity. Differences in the ionization state of the interstellarmedium do not contribute significantly to the observed differencebetween SFR([O II]) and SFR(Hα) for the NFGS galaxies withmetallicities log(O/H)+12>~8.5. The Kennicutt [O II]-SFR relationassumes a typical reddening for nearby galaxies; in practice, thereddening differs significantly from sample to sample. We derive a newSFR([O II]) calibration that does not contain a reddening assumption.Our new SFR([O II]) calibration also provides an optional correction formetallicity. Our SFRs derived from [O II] agree with those derived fromHα to within 0.03-0.05 dex. We show that the reddening, E(B-V),increases with intrinsic (i.e., reddening-corrected) [O II] luminosityfor the NFGS sample. We apply our SFR([O II]) calibration withmetallicity correction to two samples: high-redshift 0.8
| Companions of Bright Barred Shapley-Ames Galaxies
Companion galaxy environment for a subset of 78 bright and nearby barredgalaxies from the Shapley-Ames Catalog is presented. Among the spiralbarred galaxies, there are Seyfert galaxies, galaxies with circumnuclearstructures, galaxies not associated with any large-scale galaxy cloudstructure, galaxies with peculiar disk morphology (crooked arms), andgalaxies with normal disk morphology; the list includes all Hubbletypes. The companion galaxy list includes the number of companiongalaxies within 20 diameters, their Hubble type, and projectedseparation distance. In addition, the companion environment was searchedfor four known active spiral galaxies, three of them are Seyfertgalaxies, namely, NGC 1068, NGC 1097, and NGC 5548, and one is astarburst galaxy, M82. Among the results obtained, it is noted that theonly spiral barred galaxy classified as Seyfert 1 in our list has nocompanions within a projected distance of 20 diameters; six out of 10Seyfert 2 bar galaxies have no companions within 10 diameters, six outof 10 Seyfert 2 galaxies have one or more companions at projectedseparation distances between 10 and 20 diameters; six out of 12 galaxieswith circumnuclear structures have two or more companions within 20diameters.
| A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| The Westerbork HI survey of spiral and irregular galaxies. II. R-band surface photometry of late-type dwarf galaxies
R-band surface photometry is presented for 171 late-type dwarf andirregular galaxies. For a subsample of 46 galaxies B-band photometry ispresented as well. We present surface brightness profiles as well asisophotal and photometric parameters including magnitudes, diameters andcentral surface brightnesses. Absolute photometry is accurate to 0.1 magor better for 77% of the sample. For over 85% of the galaxies the radialsurface brightness profiles are consistent with published data withinthe measured photometric uncertainty. For most of the galaxies in thesample H I data have been obtained with the Westerbork Synthesis RadioTelescope. The galaxies in our sample are part of the WHISP project(Westerbork H I Survey of Spiral and Irregular Galaxies), which aims atmapping about 500 nearby spiral and irregular galaxies in H I. Theavailability of H I data makes this data set useful for a wide range ofstudies of the structure, dark matter content and kinematics oflate-type dwarf galaxies. Based on observations made with INT operatedon the island of La Palma by the Isaac Newton Group in the SpanishObservatorio del Roque de los Muchachos of the Instituto de Astrofisicade Canarias. The tables in Appendix A are only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/863. Thefigures in Appendix B are only available in electronic formhttp://www.edpsciences.org
| The Westerbork HI survey of spiral and irregular galaxies. I. HI imaging of late-type dwarf galaxies
Neutral hydrogen observations with the Westerbork Synthesis RadioTelescope are presented for a sample of 73 late-type dwarf galaxies.These observations are part of the WHISP project (Westerbork H I Surveyof Spiral and Irregular Galaxies). Here we present H I maps, velocityfields, global profiles and radial surface density profiles of H I, aswell as H I masses, H I radii and line widths. For the late-typegalaxies in our sample, we find that the ratio of H I extent to opticaldiameter, defined as 6.4 disk scale lengths, is on average 1.8 +/- 0.8,similar to that seen in spiral galaxies. Most of the dwarf galaxies inthis sample are rich in H I, with a typical Mion {Hi}/L_B of1.5. The relative H I content M_ion {HI}/L_R increases towards fainterabsolute magnitudes and towards fainter surface brightnesses. Dwarfgalaxies with lower average H I column densities also have lower averageoptical surface brightnesses. We find that lopsidedness is as commonamong dwarf galaxies as it is in spiral galaxies. About half of thedwarf galaxies in our sample have asymmetric global profiles, a thirdhas a lopsided H I distribution, and about half shows signs of kinematiclopsidedness.
| The angular momentum content of dwarf galaxies: new challenges for the theory of galaxy formation
We compute the specific angular momentum distributions for a sample oflow-mass disc galaxies observed by Swaters. We compare thesedistributions to those of dark matter haloes obtained by Bullock et al.from high-resolution N-body simulations of structure formation in aΛCDM universe. We find that although the disc mass fractions aresignificantly smaller than the universal baryon fraction, the totalspecific angular momenta of the discs are in good agreement with thoseof dark matter haloes. This suggests that discs form out of only a smallfraction of the available baryons, but yet manage to draw most of theavailable angular momentum. In addition we find that the angularmomentum distributions of discs are clearly distinct from those of thedark matter; discs lack predominantly both low and high specific angularmomenta. Understanding these findings in terms of a coherent picture fordisc formation is challenging. Cooling, feedback and stripping, whichare the main mechanisms to explain the small disc mass fractions found,seem unable to simultaneously explain the angular momentum distributionsof the discs. In fact, it seems that the baryons that make up the discsmust have been born out of angular momentum distributions that areclearly distinct from those of ΛCDM haloes. However, the dark andbaryonic mass components experience the same tidal forces, and it istherefore expected that they should have similar angular momentumdistributions. Therefore, understanding the angular momentum content ofdisc galaxies remains an important challenge for our picture of galaxyformation.
| Dwarf galaxy rotation curves and the core problem of dark matter haloes
The standard cold dark matter (CDM) model has recently been challengedby the claim that dwarf galaxies have dark matter haloes withconstant-density cores, whereas CDM predicts haloes with steeply cuspeddensity distributions. Consequently, numerous alternative dark mattercandidates have recently been proposed. In this paper we scrutinize theobservational evidence for the incongruity between dwarf galaxies andthe CDM model. To this end, we analyse the rotation curves of 20late-type dwarf galaxies studied by Swaters. Taking the effects of beamsmearing and adiabatic contraction into account, we fit mass models tothese rotation curves with dark matter haloes with different cuspslopes, ranging from constant-density cores to r-2 cusps.Even though the effects of beam smearing are small for these data, theuncertainties in the stellar mass-to-light ratio and the limited spatialsampling of the halo's density distribution hamper a unique massdecomposition. Consequently, the rotation curves in our sample cannot beused to discriminate between dark haloes with constant-density cores andr-1 cusps. We show that the dwarf galaxies analysed here areconsistent with CDM haloes in a ΛCDM cosmology, and that there isthus no need to abandon the idea that dark matter is cold andcollisionless. However, the data are also consistent with anyalternative dark matter model that produces dark matter haloes withcentral cusps less steep than r-1.5. In fact, we argue thatbased on existing Hi rotation curves alone, at best weak limits can beobtained on cosmological parameters and/or the nature of the darkmatter. In order to make progress, rotation curves with higher spatialresolution and independent measurements of the mass-to-light ratio ofthe disc are required.
| H I Gas in the Environment of the Seyfert Galaxies NGC 6764 and Markarian 1126
We present the results of a 21 cm line study of the environment of twoSeyfert galaxies: NGC 6764 and Mrk 1126. Both galaxies are embedded inlarge and slightly distorted gaseous disks that extend 2-4 times fartherthan their optical diameters. The asymmetry of the H I distribution andprofile is indicative of a weak perturbation, although one that is notstrong enough to disturb either the gas or the stars in the inner partsof the galaxies. Whereas Mrk 1126 does have a nearby companion, MCG-02-58-017, the gravitational interaction between the two galaxies isquite weak, and it is unlikely that MCG -02-58-017 is responsible fordriving the nuclear activity in Mrk 1126. NGC 6764 has no companionswithin a radius of 160 kpc. We conclude that the nuclear activity in NGC6764 and Mrk 1126 is unrelated to the galaxies' immediate environment.
| Spectrophotometry of Nearby Field Galaxies: The Data
We have obtained integrated and nuclear spectra as well as U, B, Rsurface photometry for a representative sample of 196 nearby galaxies.These galaxies span the entire Hubble sequence in morphological type, aswell as a wide range of luminosities (MB=-14 to -22). Here wepresent the spectrophotometry for these galaxies. The selection of thesample and the U, B, R surface photometry is described in a companionpaper. Our goals for the project include measuring the current starformation rates and metallicities of these galaxies, and elucidatingtheir star formation histories, as a function of luminosity andmorphology. We thereby extend the work of Kennicutt to lower luminositysystems. We anticipate that our study will be useful as a benchmark forstudies of galaxies at high redshift. We describe the observing, datareduction, and calibration techniques and demonstrate that ourspectrophotometry agrees well with that of Kennicutt. The spectra spanthe range 3550-7250 Å at a resolution (FWHM) of ~6 Å andhave an overall relative spectrophotometric accuracy of ~+/-6%. Wepresent a spectrophotometric atlas of integrated and nuclear rest-framespectra as well as tables of equivalent widths and synthetic colors. Theatlas and tables of measurements will be made available electronically.We study the correlations of galaxy properties determined from thespectra and images. Our findings include: (1) galaxies of a givenmorphological class display a wide range of continuum shapes andemission-line strengths if a broad range of luminosities are considered,(2) emission-line strengths tend to increase and continua tend to getbluer as the luminosity decreases, and (3) the scatter on the generalcorrelation between nuclear and integrated Hα emission-linestrengths is large.
| Surface Photometry of Nearby Field Galaxies: The Data
We have obtained integrated spectra and multifilter photometry for arepresentative sample of ~200 nearby galaxies. These galaxies span theentire Hubble sequence in morphological type, as well as a wide range ofluminosities (MB=-14 to -22) and colors (B-R=0.4-1.8). Herewe describe the sample selection criteria and the U, B, R surfacephotometry for these galaxies. The spectrophotometric results will bepresented in a companion paper. Our goals for the project includemeasuring the current star formation rates and metallicity of thesegalaxies, and elucidating their star formation histories, as a functionof luminosity and morphology. We thereby extend the work of Kennicutt tolower luminosity systems. We anticipate that our study will be useful asa benchmark for studies of galaxies at high redshift. We discuss theobserving, data reduction, and calibration techniques and show that ourphotometry agrees well with previous work in those cases in whichearlier data are available. We present an atlas of images, radialsurface brightness profiles, and color profiles as well as tables ofderived parameters. The atlas and tables of measurements will be madeavailable electronically. We study the correlations of galaxy propertiesdetermined from the galaxy images. Our findings include the following:(1) colors determined within the effective radius correlate better withmorphological type than with MB and (2) 50% of thelow-luminosity galaxies are bluest in their centers.
| 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.
| Gas-Rich Companions of Isolated Galaxies
We have used the VLA to search for gaseous remnants of the galaxyformation process around six extremely isolated galaxies. We found twodistinct H I clouds around each of two galaxies in our sample (UGC 9762and UGC 11124). These clouds are rotating and appear to have opticalcounterparts, strongly implying that they are typical dwarf galaxies.The companions are currently weakly interacting with the primary galaxybut look to be in stable orbits as they have dynamical frictiontimescales of 5-100 Gyr. In one case, (UGC 11124N), we see ongoingaccretion of the companion onto the primary galaxy. The small mass ratioinvolved in this interaction means that the resulting merger will be aminor one. The companion does, however, contain enough gas that themerger will represent a significant infusion of fuel to drive futurestar formation in UGC 11124 while building up the mass of the disk.
| 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.
Not Available
| 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.
| 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.
| HI Observations of Barred Magellanic Spirals.I.Global Properties
We present observations of the H I content of a sample of BarredMagellanic spiral type galaxies. The data are consistent with the factthat SBm systems are late-type spirals and not irregular galaxies. Thebarred morphology that is evident in the optical structure of thesegalaxies manifests itself in both the distribution and kinematics of theneutral gas. The H I is also distributed well beyond the optical extentof each galaxy. We have detected the presence of small (~10^7^ M_sun_) HI clouds around four of the five galaxies in this sample. Most of theclouds appear to be actively interacting with their primary galaxy andhave no optical counterparts on the Digital Sky Survey images. Wespeculate that the barred morphology and kinematics of these galaxiesmay be the result of their interaction with such neighboring clouds.Additionally, the presence of these clouds and their relationship withthe primary galaxies suggests that the process of galaxy formationcontinues in the present epoch.
| 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.
| Redshift periodicity in the Local Supercluster.
Persistent claims have been made over the last ~15yr that extragalacticredshifts, when corrected for the Sun's motion around the Galacticcentre, occur in multiples of ~24 or ~36km/s. A recent investigation byus of 40 spiral galaxies out to 1000km/s, with accurately measuredredshifts, gave evidence of a periodicity ~37.2-37.7km/s. Here we extendour enquiry out to the edge of the Local Supercluster (~2600km/s),applying a simple and robust procedure to a total of 97 accuratelydetermined redshifts. We find that, when corrected for related vectorsclose to recent estimates of the Sun's galactocentric motion, theredshifts of spirals are strongly periodic (P~37.6km/s). The formalconfidence level of the result is extremely high, and the signal is seenindependently with different radio telescopes. We also examine a furthersample of 117 spirals observed with the 300-foot Green Bank telescopealone. The periodicity phenomenon appears strongest for the galaxieslinked by group membership, but phase coherence probably holds overlarge regions of the Local Supercluster.
| 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.
| The Case Low-Dispersion Northern Sky Survey. XV. A Region in Ursa Major and Canes Venatici
Positions, estimated magnitudes, and finding charts (when necessary) areprovided for 228 blue and/or emission-line galaxies, H II regions ingalaxies, 114 unresolved blue and/or emission-line objects, includingQSO candidates, and 47 known and suspected blue stars in a ~148 deg^2^region in southeastern Ursa Major and western Canes Venatici in theregion 11^h^00^m^ < R.A. < 12^h^30^m^ and +38^deg^ < Decl. <+47^deg^ ( 1950). The objects, whose blue magnitudes are mostly withinthe range 15-18, were identified on low-dispersion objective-prismplates taken with the Burrell Schmidt telescope at Kitt Peak.
| 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.
| Integrated photoelectric magnitudes and color indices of bright galaxies in the Johnson UBV system
The photoelectric total magnitudes and color indices published in theThird Reference Catalogue of Bright Galaxies (RC3) are based on ananalysis of approximately equals 26,000 B, 25,000 B-V, and 17,000 U-Bmultiaperture measurements available up to mid 1987 from nearly 350sources. This paper provides the full details of the analysis andestimates of internal and external errors in the parameters. Thederivation of the parameters is based on techniques described by theVaucouleurs & Corwin (1977) whereby photoelectric multiaperture dataare fitted by mean Hubble-type-dependent curves which describe theintegral of the B-band flux and the typical B-V and U-B integrated colorgradients. A sophisticated analysis of the residuals of thesemeasurements from the curves was made to allow for the random andsystematic errors that effect such data. The result is a homogeneous setof total magnitudes BTA total colors(B-V)T and (U-B)T, and effective colors(B-V)e and (U-B)e for more than 3000 brightgalaxies in RC3.
| Global properties of dwarf galaxies. I. Galaxy sample and IRAS infrared flux-densities
We have selected a sample of 278 dwarf galaxies for which at least Bmagnitudes and preferably also optical colour information are available.For those galaxies that have no previously published IRAS fluxes, wehave used the IRAS database to extract fluxes or upper limits tosensitivity levels significantly better than those of the IRAS PointSource Catalog. New IRAS data include 79 galaxies detected in at leastone band, and 66 galaxies with good upper limits. In total, about 60% ofall dwarf galaxies in the sample now have been detected at 60/100μm.
| Global properties of dwarf galaxies II. Colours and luminosities
We have used a previously determined sample of 278 dwarf galaxies formost of which B magnitudes, optical colours, HI fluxes and IRASflux-densities are known, in order to derive luminosities, colours andsurface brightnesses. Dwarf galaxy properties are compared to those of acontrol sample of 228 larger spiral galaxies. The dwarf galaxies have onaverage higher 60/100μm flux ratios and lower 12/25μm flux ratiosthan the spiral galaxies, indicating that the contribution of `cirrus'to the infrared emission from dwarf galaxies is relativelyinsignificant. In the dwarf galaxies, the 60/100μm flux ratioincreases with increasing optical blueness; spiral galaxies show theopposite. Dwarf galaxies with a low optical surface brightness have low100μm/HI ratios, but the converse is not true. Galaxies with high100μm/HI ratios (indicative of high dust-to-gas ratios) also havehigh FIR/B ratios as well as high 60/100μm flux-density ratios.Although this is true for both spiral and dwarf galaxies, at given100μm/HI ratios the dwarf galaxies have both a lower FIR/B ratio anda higher 60/100μm flux-density ratio. This result is of importance inthe interpretation of FIR/B - 60/100μm diagrams in terms of starformation activity.
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