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Публикации по объекту
Multicomponent decompositions for a sample of S0 galaxies
We have estimated the bulge-to-total (B/T) light ratios in theKs band for a sample of 24 S0, S0/a and Sa galaxies byapplying a two-dimensional multicomponent decomposition method. For thedisc an exponential function is used, the bulges are fitted by aSérsic R1/n function and the bars and ovals aredescribed either by a Sérsic or a Ferrers function. In order toavoid non-physical solutions, preliminary characterization of thestructural components is made by inspecting the radial profiles of theorientation parameters and the low azimuthal wavenumber Fourieramplitudes and phases. In order to identify also the inner structures,unsharp masks were created: previously undetected inner spiral arms werefound in NGC 1415 and marginally in NGC 3941. Most importantly, we foundthat S0s have a mean K ratio of 0.24 +/- 0.11,which is significantly smaller than the mean R=0.6 generally reported in the literature. Also, the surface brightnessprofiles of the bulges in S0s were found to be more exponential-likethan generally assumed, the mean shape parameter of the bulge being= 2.1 +/- 0.7. We did not find examples of barred S0s lackingthe disc component, but we found some galaxies (NGC 718, 1452 and 4608)having a non-exponential disc in the bar region. To our knowledge, ourstudy is the first attempt to apply a multicomponent decompositionmethod for a moderately sized sample of early-type disc galaxies.
| Near-Infrared Integral Field Spectroscopy of Star-forming Galaxies
The Palomar Integral Field Spectrograph was used to probe a variety ofenvironments in nine nearby galaxies that span a range of morphologicaltypes, luminosities, metallicities, and infrared-to-blue ratios. For thefirst time, near-infrared spectroscopy was obtained for nuclear orbright H II regions in star-forming galaxies over two spatial dimensions(5.7"×10.0") in the [Fe II] (1.257 μm), [Fe II] (1.644 μm),Paβ (1.282 μm), H2 (2.122 μm), and Brγ(2.166 μm) transition lines. These data yield constraints on variouscharacteristics of the star-forming episodes in these regions, includingtheir strength, maturity, spatial variability, and extinction. The H IIregions stand out from the nuclei. Unlike observations of nuclearregions, H II region near-infrared observations do not show a spatialcoincidence of the line and continuum emission; the continuum and linemaps of H II regions usually show distinct and sometimes spatiallyseparated morphologies. Gauging from Paβ and Brγ equivalentwidths and luminosities, the H II regions have younger episodes of starformation than the nuclei and more intense radiation fields.Near-infrared line ratio diagnostics suggest that H II regions have``purer'' starbursting properties. The correlation between ionizingphoton density and mid-infrared color is consistent with the starformation activity level being higher for H II regions than for nuclei.And though the interpretation is complicated, on a purely empiricalbasis the H II regions show lower Fe1+ abundances than nucleiby an order of magnitude.
| Optical Imaging and Spectroscopy of the Edge-on Sbc Galaxy UGC 10043: Evidence for a Galactic Wind and a Peculiar Triaxial Bulge
We present new optical imaging and spectroscopy of the peculiar, edge-onSbc galaxy UGC 10043. Using the WIYN telescope, we have obtained B, R,and Hα+[NII] images, together with DensePak integral fieldspectroscopic measurements of the stellar Ca II infrared triplet and theHα and [N II] lines from the ionized gas. The imaging observationsshow that the inner bulge of UGC 10043 (a<=7.5") is elongatedperpendicular to the galaxy major axis. At larger r the bulge isophotestwist to become oblate and nearly circular, suggesting the bulge istriaxial. The bulge shows no clear evidence for rotation about eitherits major or minor axis. The inner, southwestern quadrant of the bulgeis girdled by a narrow dust lane parallel to the minor axis; unsharpmasking reveals that this minor-axis dust lane may be part of an innerpolar ring, although we find no unambiguous kinematic evidence oforthogonally rotating material. The stellar disk of UGC 10043 has arather low optical surface brightness [μ(0)R,i~23.2 magarcsec-2], a small scale height (hz=395 pc forD=33.4 Mpc), and a mild integral sign warp. A dusty, inner diskcomponent that appears tilted relative to the outlying disk is alsoseen. The Hα and [N II] emission lines in UGC 10043 resolve intomultiple velocity components, indicating the presence of a large-scalegalactic wind with an outflow velocity of Vout>~104 kms-1. Hα+[NII] imaging reaffirms this picture byrevealing ionized gas extended to |z|~3.5 kpc in the form of a roughlybiconical structure. The [N II]/Hα line intensity ratio increaseswith increasing distance from the plane, reaching values as high as 1.7.Unlike most galaxies with large-scale winds, UGC 10043 has only a modestglobal star formation rate (<~1 Msolar yr-1),implying the wind is powered by a rather feeble central starburst. Wediscuss evolutionary scenarios that could account for both thestructural complexities of UGC 10043 and its large-scale wind. The mostplausible scenarios require a major accretion or merger event at least afew gigayears ago.
| Spiral galaxies observed in the near-infrared K band. I. Data analysis and structural parameters
Deep surface photometry in the K band was obtained for 54 normal spiralgalaxies, with the aim of quantifying the percentage of faint bars andstudying the morphology of spiral arms. The sample was chosen to cover awider range of morphological types while inclination angles anddistances were limited to allow a detailed investigation of the internalstructure of their disks and future observations and studies of the diskkinematics. An additional constraint for a well defined subsample wasthat no bar structure was seen on images in the visual bands. Accuratesky projection parameters were determined from the K maps comparingseveral different methods. The surface brightness distribution wasdecomposed into axisymmetric components while bars and spiral structureswere analyzed using Fourier techniques.Bulges were best represented by a Sérsic r1/n law withan index in the typical range of 1-2. The central surface brightness ofthe exponential disk and bulge-to-disk ratio only showed weakcorrelation with Hubble type. Indications of a central point source werefound in many of the galaxies. An additional central, steep, exponentialdisk improved the fit for more than 80% of the galaxies suggesting thatmany of the bulges are oblate.Bars down to the detection level at a relative amplitude of 3% weredetected in 26 of 30 galaxies in a subsample classified as ordinary SAspirals. This would correspond to only 5% of all spiral galaxies beingnon-barred at this level. In several cases, bars are significantlyoffset compared to the starting points of the main spiral pattern whichindicates that bar and spiral have different pattern speeds. A smallfraction (10%) of the sample has complex central structuresconsisting of several sets of bars, arcs or spirals.A majority of the galaxies (60%) displays a two-armed, grand-designspiral pattern in their inner parts which often breaks up into multiplearms in their outer regions. Phase shifts between the inner and outerpatterns suggest in some cases that they belong to different spiralmodes. The pitch angles of the main two-armed symmetric spiral patternin the galaxies have a typical range of 5-30 °. The sample shows alack of strong, tight spirals which could indicate that such patternsare damped by non-linear, dynamical effects due to their high radialforce perturbations.Based on observations collected at the European Southern Observatory, LaSilla, Chile; programs: ESO 63.N-0343, 65.N-0287, 66.N-0257.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/423/849Appendix A is only available in electronic form athttp://www.edpsciences.org
| Minor-axis velocity gradients in disk galaxies
We present the ionized-gas kinematics and photometry of a sample of 4spiral galaxies which are characterized by a zero-velocity plateau alongthe major axis and a velocity gradient along the minor axis,respectively. By combining these new kinematical data with thoseavailable in the literature for the ionized-gas component of the S0s andspirals listed in the Revised Shapley-Ames Catalog of Bright Galaxies werealized that about 50% of unbarred galaxies show a remarkable gasvelocity gradient along the optical minor axis. This fraction rises toabout 60% if we include unbarred galaxies with an irregular velocityprofile along the minor axis. This phenomenon is observed all along theHubble sequence of disk galaxies, and it is particularly frequent inearly-type spirals. Since minor-axis velocity gradients are unexpectedif the gas is moving onto circular orbits in a disk coplanar to thestellar one, we conclude that non-circular and off-plane gas motions arenot rare in the inner regions of disk galaxies.Based on observations carried out at the European Southern Observatoryin La Silla (Chile) (ESO 69.B-0706 and 70.B-0338), with the MultipleMirror Telescope which is a joint facility of the SmithsonianInstitution and the University of Arizona, and with the ItalianTelescopio Nazionale Galileo (AOT-5, 3-18) at the Observatorio del Roquede los Muchachos in La Palma (Spain).Table 1 is only available in electronic form athttp://www.edpsciences.org. Table 5 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/507
| Disk-bulge decompositions of spiral galaxies in UBVRI
A sample of 26 bright spiral galaxies (Btot < 12.7) withlow to medium inclination and without a bar was observed with UBVRIfilters. The CAFOS focal reducer camera at the Calar Alto 2.2 mtelescope was used. The surface-brightness distributions were fittedusing a 2-dimensional algorithm with corresponding functions for thedisk- and bulge-structure. For the disks an exponential function wasused, for the bulges a Sérsic Rβ law, was appliedwith the concentration parameter β = 1/n as another fit variable.Correlations of the resulting structural parameters of disks and bulgesin UBVRI are investigated, giving clues to the formation history of thebulges.We confirm that the large and bright bulges of early-type spirals aresimilar to elliptical galaxies. They were probably formed prior to thedisks in a monolithic collapse or via early mergers. Late-type spiralshave tiny and faint bulges with disk-like profiles. These bulges wereprobably formed after the disk in secular evolution processes, e.g. froma disk instability. The comparison of the color indices of correspondingspirals and bulges with population synthesis computations support aboveformation scenarios.Tables 2-4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/415/63
| Inner polar disks in early-type spiral galaxies
We measured a remarkable gas velocity gradient along the minor axis of anumber of early-type spiral galaxies. This phenomenon suggests thepresence of a kinematically-decoupled component in orthogonal rotationwith respect to the galaxy disk which we named inner polar disk. If thisis the case a second event has taken place in the history of the galaxy.Alternatively the gas velocity gradient is the result of non-circularmotions induced by the potential of a triaxial bulge.
| Minor-axis velocity gradients in spirals and the case of inner polar disks
We measured the ionized-gas and stellar kinematics along the major andminor axis of a sample of 10 early-type spirals. Much to our surprise wefound a remarkable gas velocity gradient along the minor axis of 8 ofthem. According to the kinematic features observed in their ionized-gasvelocity fields, we divide our sample galaxies in three classes ofobjects. (i) NGC 4984, NGC 7213, and NGC 7377 show an overall velocitycurve along the minor axis without zero-velocity points, out to the lastmeasured radius, which is interpreted as due to the warped structure ofthe gaseous disk. (ii) NGC 3885, NGC 4224, and NGC 4586 arecharacterized by a velocity gradient along both major and minor axis,although non-zero velocities along the minor axis are confined to thecentral regions. Such gas kinematics have been explained as being due tonon-circular motions induced by a triaxial potential. (iii) NGC 2855 andNGC 7049 show a change of slope of the velocity gradient measured alongthe major axis (which is shallower in the center and steeper away fromthe nucleus), as well as non-zero gas velocities in the central regionsof the minor axis. This has been attributed to the presence of akinematically-decoupled gaseous component in orthogonal rotation withrespect to the galaxy disk, namely an inner polar disk. The case andorigin of inner polar disks are discussed and the list of their hostgalaxies is presented.Based on observations carried out at the European Southern Observatory(ESO 62.A-0463 and 63.N-0305).Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/408/873
| 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
| 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.
| The orthogonal gaseous kinematical decoupling in the Sa spiral NGC 2855
We present major and minor-axis kinematics of stars and ionized gas aswell as narrow and broad-band surface photometry of the Sa spiral NGC2855. In the nuclear regions of this unbarred and apparently undisturbedspiral galaxy the gas is rotating perpendicularly to the galaxy disk. Wesuggest that this kinematically-decoupled component is the signature ofan acquisition process in the history of this galaxy. Based onobservations carried out at the Observatorio del Roque de los Muchachos,La Palma (Spain) with the Italian Telescopio Nazionale Galileo and atthe European Southern Observatory, La Silla (Chile) (ESO 62.N-0463 and67.B-0230). Tables 3 and 4 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/382/488
| Surface photometry of spiral galaxies in NIR: Structural parameters of disks and bulges
A sample of 40 bright spiral galaxies (BT < 12) with lowinclination and without bar was observed with JHK filters. For thispurpose the MAGIC NICMOS3 camera at the 2.2 m telescope of the CalarAlto observatory, Spain was used. With a newly developed 2-dimensionalalgorithm the distribution of the surface brightness was fittedsimultaneously by corresponding functions for the disk- andbulge-structure. While the disk was fitted with an exponential function,the bulge profile was fitted with a generalized de VaucouleursRbeta law, with the concentration parameter beta = 1/n as afurther fit variable. The correlation of the resulting structuralparameters of disks and bulges lead to some interesting relations: 1.The use of a variable exponent beta is necessary for a realisticdescription of the bulge structure; 2. Disks and bulges show similarcorrelations between effective radius, effective surface brightness andluminosity; 3. They populate a common strip in the fundamental plane; 4.From the correlations between beta and Hubble type some conclusionsabout the formation and evolution of spiral galaxies can be drawn.
| A Subarcsecond Resolution Near-Infrared Study of Seyfert and ``Normal'' Galaxies. II. Morphology
We present a detailed study of the bar fraction in the CfA sample ofSeyfert galaxies and in a carefully selected control sample of nonactivegalaxies to investigate the relation between the presence of bars and ofnuclear activity. To avoid the problems related to bar classification inthe Third Reference Catalogue (RC3), e.g., subjectivity, low resolution,and contamination by dust, we have developed an objective barclassification method, which we conservatively apply to our newsubarcsecond resolution near-infrared (NIR) imaging data set discussedin the first paper in this series. We are able to use stringent criteriabased on radial profiles of ellipticity and major axis position angle todetermine the presence of a bar and its axial ratio. Concentrating onnoninteracting galaxies in our sample for which morphologicalinformation can be obtained, we find that Seyfert hosts are barred moreoften (79%+/-7.5%) than the nonactive galaxies in our control sample(59%+/-9%), a result which is at the ~2.5 σ significance level.The fraction of nonaxisymmetric hosts becomes even larger wheninteracting galaxies are taken into account. We discuss the implicationsof this result for the fueling of central activity by large-scale bars.This paper improves on previous work by means of imaging at higherspatial resolution and by the use of a set of stringent criteria for barpresence and confirms that the use of NIR is superior to optical imagingfor detection of bars in disk galaxies.
| A Subarcsecond-Resolution Near-Infrared Study of Seyfert and ``Normal'' Galaxies. I. Imaging Data
We present new high-resolution near-infrared observations in the J, H,and K bands, obtained to study the properties of Seyfert host galaxies.The data set consists of images in the three bands of practically theentire CfA sample of Seyfert galaxies, and K-band images of a controlsample of nonactive, ``normal,'' galaxies, matched to the Seyfert samplein the distribution of type and inclination. The spatial resolution andsampling of the new images is a factor of 2 better than previouslypublished K-band data. In this paper, we present the data in the form ofprofiles of surface brightness and color, ellipticity and major axisposition angle, as well as gray-scale maps of surface brightness in H orK and both J-H and H-K colors. We compare our surface brightness andcolor profiles with the literature and find good agreement. Our data arediscussed in detail in three subsequent publications, where we analyzethe morphologies of Seyfert and normal hosts, quantify the strength ofnonaxisymmetric features in disks and their relationship to nuclearactivity, address the question of bar fraction in Seyferts and normalgalaxies, and analyze the color information in the framework of emissionmechanisms in Seyfert 1's and 2's and in nonactive galaxies.
| Bulge-Disk Decomposition of 659 Spiral and Lenticular Galaxy Brightness Profiles
We present one of the largest homogeneous sets of spiral and lenticulargalaxy brightness profile decompositions completed to date. The 659galaxies in our sample have been fitted with a de Vaucouleurs law forthe bulge component and an inner-truncated exponential for the diskcomponent. Of the 659 galaxies in the sample, 620 were successfullyfitted with the chosen fitting functions. The fits are generally welldefined, with more than 90% having rms deviations from the observedprofile of less than 0.35 mag. We find no correlations of fittingquality, as measured by these rms residuals, with either morphologicaltype or inclination. Similarly, the estimated errors of the fittedcoefficients show no significant trends with type or inclination. Thesedecompositions form a useful basis for the study of the lightdistributions of spiral and lenticular galaxies. The object base issufficiently large that well-defined samples of galaxies can be selectedfrom it.
| Lopsidedness in Early-Type Disk Galaxies
We quantify the mean asymmetry of 54 face-on, early-type disk galaxies(S0 to Sab) using the amplitude of the m = 1 azimuthal Fourier componentof the R-band surface brightness. We find that the median lopsidedness,, of our sample is 0.11 and that the most lopsided 20% ofour galaxies have >= 0.19. Asymmetries in early-typedisks appear to be of similar frequency and strength as in late-typedisk galaxies. We have observed our early-type disks in a bandpass (Rband) in which the light is dominated by stars with ages greater than10^9 yr and therefore are seeing azimuthal asymmetries in the stellarmass distribution. The similar degree of lopsidedness seen in disks ofvery different star formation rates indicates that the lopsidedness inall galactic disks is primarily due to azimuthal mass asymmetries.Hence, 20% of all disk galaxies (regardless of Hubble type) haveazimuthal asymmetries, >= 0.19, in their stellar diskmass distribution, confirming lopsidedness as a dynamical phenomenon.
| 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.
| HI in shell galaxies and other merger remnants
The few elliptical galaxies with detected HI almost always seem to haveoptical peculiarities as well, though these are often well hidden andrequire special image enhancement techniques to reveal them. In thispaper we show several deep images of ellipticals with optical shellswhich are associated with HI, and suggest that mergers, or at leastencounters with gas-rich galaxies are responsible. We also show somedisk galaxies with unusual faint extensions, some of them the kinds ofinteractions that may result in HI in ellipticals. These illustrationsare drawn from an atlas of low surface brightness images of brightgalaxies currently in preparation.
| Diffuse Stellar Light at 100 Kiloparsec Scales in M87
In a new survey of nearby galaxies from stacked photographic images,seemingly regular galaxies of several types show amorphous, oftenasymmetrical features at very faint levels (28 mag arcsec-2). In M87, adiffuse fan of stellar material extends along the projected southeast(major) axis out to about 100 kpc. We suggest that accretion of a smallspheroidal galaxy into a larger potential is the most likely explanationfor the diffuse structure. The orbit is required to pass close to thecenter of the potential in order to produce a fan that is nearly alignedwith the major axis and has a large opening angle, as seen in M87. Oursimulations include a rigid primary potential with characteristicssimilar to those derived for M87 and a populated secondary potential. Weinvestigate the structure of the dark matter at large galactic radii byrepresenting M87 with different potentials. The morphologies of thedebris of intruder spheres and disks of different masses and orbitalparameters limit the possible accretion scenarios. The total luminosityof the fan and the kinematics of debris in the center of the primarypotential are analyzed and compared with substructure in M87. The shortlifetimes (tfan <~ 5 x 108 yr) of the simulated diffuse fans and lackof observed shells indicates either that we are seeing M87 at a "specialtime" during its evolution or that infall from small intruder galaxiesis common. Our simulations indicate that several accretion events couldbe hidden in galaxies. For many orbits, intruder material is quicklyspread out to very low light levels. Observations of the high specificfrequency of globular clusters in M87 provide evidence that the galaxymay experience frequent accretions of this type.
| 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.
| The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
| A comparative study of morphological classifications of APM galaxies
We investigate the consistency of visual morphological classificationsof galaxies by comparing classifications for 831 galaxies from sixindependent observers. The galaxies were classified on laser print copyimages or on computer screen using scans made with the Automated PlateMeasuring (APM) machine. Classifications are compared using the RevisedHubble numerical type index T. We find that individual observers agreewith one another with rms combined dispersions of between 1.3 and 2.3type units, typically about 1.8 units. The dispersions tend to decreaseslightly with increasing angular diameter and, in some cases, withincreasing axial ratio (b/a). The agreement between independentobservers is reasonably good but the scatter is non-negligible. In spiteof the scatter, the Revised Hubble T system can be used to train anautomated galaxy classifier, e.g. an artificial neural network, tohandle the large number of galaxy images that are being compiled in theAPM and other surveys.
| A Catalog of Stellar Velocity Dispersions. II. 1994 Update
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
| 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.
| Molecular gas in starburst galaxies: line intensities and physical conditions
In a study of molecular gas in IR-bright galaxies, we have observed thecentral position in ^12^CO J=1-0, J=2-1; ^13^CO J=1-0, J=2-1; C^18^OJ=1-0 and HCN J=1-0 line emission. The sample (in total 32 galaxies)consists of starburst galaxies, interacting galaxies and two quiescentsystems. We find a mean ^12^CO 2-1/1-0 line ratio of 0.93+/-0.22, and amean ^13^CO 2-1/1-0 line ratio of 1.3+/-0.66. The mean ^12^CO/^13^CO 1-0ratio (=R(1-0)) is =~13+/-6 and for ^12^CO/^13^CO 2-1 it is =~13+/-5.The mean ^12^CO/HCN 1-0 ratio is =~16. The ^12^CO/C^18^O 1-0 intensityratio ranges from 20 to 140 in 6 galaxies. These values of ratios referto central positions corrected for effects of beam-size and source-size.A considerable fraction of the ^13^CO emission may be saturated andoriginate in dense cores of smaller volume filling factor than thesurrounding ^12^CO-emitting gas. High gas temperatures and turbulencework against large optical depths in the ^12^CO 1-0 line of the envelopegas. In contrast to what is usually assumed for the ^12^CO 1-0 line, weinfer moderate optical depths, τ=~1, for the dominant^12^CO-emitting structure. We have found that galaxies with largeintensity ratios of [C II] 158 μm to ^12^CO 1-0 also have ^12^CO2-1/1-0 ratios >=0.8, implying that the ^12^CO-emitting gas may beboth dense and hot enough to excite the [C II] 158 μm line, acharacteristic of warm (T_k_ > 100K), photon-dominated regions. Wehave not found a correlation between the intensity ratio, I(CO)/I(HCN),and disturbed morphology, far-infrared emission, or measures ofstar-forming activity in our sample of galaxies, in contrast to thefindings of Solomon et al. (1992). The ^12^CO/HCN intensity ratio isquite uniform over a sample of 11 interacting galaxies and mergers. HCNis not detected in the one isolated spiral in the sample. Furthermore,we have observed R(1-0) in off-centre positions in 6 galaxies: NGC 1808,NGC 3256, NGC 4038/39, NGC 5055, NGC 6221 and NGC 7552. Offset positionsin the ^12^CO/^13^CO 2-1 intensity ratio have been observed in 3galaxies: NGC 660, NGC 2146 and Arp 299. We suggest that galaxies thatdisplay significant variation in the ratio, such as the merger NGC 3256,have at least two populations of molecular cloud ensembles:high-pressure clouds in the centre and an extended disk-component ofmore quiescent clouds. The molecular gas in the centres of luminousmergers with large gas surface densities (>10^4^Mȯ/pc^2^) willbe highly turbulent. In general, we suggest that R(1-0) is a measure ofthe cloud environment: the extreme values R(1-0)>20 originate inturbulent, high-pressure gas in the centres of luminous mergers;intermediate ratios 10<~R(1-0)<~15 originate in the inner kpc ofmore normal starburst galaxies; small ratios R(1-0)=~6 are a signatureof a disk population of clouds. We address the notion that abundanceanomalies cause the elevated values of R(1-0) in luminous merginggalaxies. To some extent, this notion rests on the assumption ofτ>>1 in the ^12^CO 1-0 line. We demonstrate how thisassumption may be flawed and conclude that in order to measureabundances in the molecular medium, one must carefully model thephysical properties of the molecular gas. Although abundances may beunusual in extreme mergers, they are only one aspect of the propertiesof the molecular gas in these regions.
| The dependence of the cool matter content on galaxy morphology in galaxies of types E/S0, S0, and SA
Using the material assembled in earlier papers, we examine the manner inwhich the interstellar matter content varies along the Hubble sequencefrom S0 galaxies to Sa galaxies selected from the RSA2 compilation. Forthis we make use of a new and more detailed classification which isdescribed here as applied to these early disk/spiral galaxies. Theprominence of the disk in S0's and the visibility of features (H IIregions) in the Sa's serve as the basis for the subtypes. Three S0categories: subtle, intermediate, and pronounced, and four Sadescriptors: very early, early, intermediate, and late are assigned tothe galaxies. It is found that the total amount of hydrogen (H I + H2)is a function of subtype, being low in the S0's and rising smoothly fromthe early Sa's to the later Sa's. The average surface density ofhydrogen exceeds 3 solar masses/pc-squared only in the latest subtypesof the Sa's. We conclude that the prominence of the disk of a galaxyclosely follows the amount of cool gas which the disk contains.
| Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
| Multiband analysis of the surface brightness distributions of SB and SC spirals from CCD images. II - Bulge-disc decomposition
We analyze the structure of a small sample of galaxies, using a set ofCCD images in standard photometric bands presented in a previous paper(Prieto et al. 1991). These and their combinations in the form of colorindex images, offer high quality information about the structure of thegalaxies, allowing us to pick out the major concentrations of dust andstar formation, notably in the intermediate zone between bulge and disk.The detection of these structures allows us to interpret the radialluminosity profiles of the galaxies, in particular where these showdepartures from the simple sum of an R exp 1/4 law bulge component andan exponential disk component. The radial color index profiles are shownto be especially useful in revealing the presence of a true bulge andhence in effecting a reliable bulge-disk decomposition. We infer that inall the galaxies examined here, the causes of observed departures fromsimple two-component bulge + disk models for radial profiles are to befound in the intermediate zones of the galaxies, and are the enhancedyoung stellar populations and the associated dust concentrationsencountered in these zones.
| Groups of galaxies within 80 Mpc. I - Grouping hierarchical method and statistical properties
An all-sky sample of 4143 galaxies comprising all the objects with anapparent diameter D(25) larger than 100 arcsec and with recessionvelocities smaller than 6000 km/s (i.e., closer than 80 Mpc) wasanalyzed using a hierarchical algorithm similar to Tully's (1987)algorithm, in order to classify the galaxies into groups defined asentities having an average luminosity density higher than 8 x 10 exp 9solar luminosity in the B band/Mpc cubed. The hierarchy is built on themass density of the aggregates progressively formed by the method,corrected for the loss of faint galaxies with the distance. In this way,264 groups of at least three members were identified, among which 82have more than five members and are located at distances lower than 40Mpc. It was found that (1) almost all the crossing times are lower thanH0 exp -1, confirming the bound nature of the groups; (2) themedian virial mass to blue luminosity ratio of the groups is 74 solarmass per solar luminosity in the B band; and (3) the M/L ratio increaseswith the group size, indicating the presence of dark matter aroundgalaxies to a distance of 500 kpc.
| Interstellar matter in early-type galaxies. I - The catalog
A catalog is given of the currently available measurements ofinterstellar matter in the 467 early-type galaxies listed in the secondedition of the Revised Shapley-Ames Catalog of Bright Galaxies. Themorphological type range is E, SO, and Sa. The ISM tracers are emissionin the following bands: IRAS 100 micron, X-ray, radio, neutral hydrogen,and carbon monoxide. Nearly two-thirds of the Es and SOs have beendetected in one or more of these tracers. Additional observed quantitiesthat are tabulated include: magnitude, colors, radial velocity, centralvelocity dispersion, maximum of the rotation curve, angular size, 60micron flux, and supernovae. Qualitative statements as to the presenceof dust or emission lines, when available in the literature, are given.Quantities derivative from the observed values are also listed andinclude masses of H I, CO, X-ray gas, and dust as well as an estimate ofthe total mass and mass-to-luminosity ratio of the individual galaxies.
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