Seeing Galaxies through Thick and Thin. II. Direct Measures of Extinction in Spiral Disks through Spectroscopy of Overlapping Galaxies
We use slit spectroscopy of overlapping pairs of galaxies to directlydetermine the extinction in disks of foreground spiral galaxies. TheDoppler shifts of pair members are determined via cross-correlation, andtheir relative correlation amplitudes are used to separate theircontributions to the combined spectra in regions of overlap. Thisspectroscopic approach is less subject to stringent symmetry constraintsthan our previous, purely photometric analyses. Extinctions offoreground members were obtained for six of the candidates in our sampleof 18 mostly spiral/spiral pairs, when the signal-to-noise-ratio andvelocity differences were suitable. In agreement with our previousimaging results, we find that the extinction in interarm regions is verymodest, typically AB~0.1 mag (corrected to face-on), whilespiral arms exhibit higher extinctions of ~0.3 mag.
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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.
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Line-of-sight velocity distributions of 53 early-type galaxies
55 long-slit spectra of 53 early-type galaxies were observed at LaSilla/ESO and reduced using standard methods. The line-of-sight velocitydistributions (LOSVDs) were measured using the fourier quotient methodand the fourier fitting method as described by van der Marel et al.(\cite{vdmarel93}). 32% of the examined galaxies contain kinematicallydecoupled stellar omponents, the size of these cores was 0.40 +/- 0.28kpc, in each case the core was smaller than 1 kpc. Analysis of thekinematics reveals in 49% of the sample galaxies the signature of astellar disk component, in 15% this is uncertain. There is evidence thatthe phenomenon of kinematically decoupled components is present in thewhole class of early-type galaxies. Several correlations betweenphotometric and kinematic parameters like the (v/sigma )* vs.epsilon diagram, the anisotropy - luminosity correlation or kappa -spacewere as well examined using measurement results for spectroscopic dataand photometric data out of literature. It is also shown that thosesample galaxies with kinematically decoupled components are more likelyto be found in groups of high density, strengthening the assumption thatsuch components are remnants of merging events. Full Fig. 6 is onlyavailable at http://www.edpsciences.org
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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.
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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.
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A Spectrophotometric Survey of Merging Galaxies
We present long-slit spectrophotometry of 40 merging or stronglyinteracting galaxy systems in the wavelength range 3650-7100 A. Alongwith optically selected objects, the sample includes 10 ultraluminousIRAS galaxies with evidence of ongoing merger activity. The data show awide variety of phenomena, with spectra resembling those of isolatedelliptical galaxies, early and late-type spiral galaxies, activegalactic nuclei starbursts, and poststarburst systems.
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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.
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Spectrophotometric Properties of Merging Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...450..547L&db_key=AST
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Multicolor surface photometry of early-type galaxies. I.
We have obtained v,g,r and i CCD surface photometry for a sample of 109early-type galaxies. Many of the galaxies covered have no previouslypublished CCD or aperture photometry. Our surface brightness profilestypically extend down to a surface brightness ofμ_r_~24mag/arcsec^2^. Detailed comparisons with previously publishedwork, and internal and external error estimates for all quantities areprovided. The complete surface photometry data set is made available ina computer-readable form.
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Kinematics of Elliptical Galaxies in Arp Groups
Not Available
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On the relationship between radio emission and optical properties in early-type galaxies
To study the origin of radio activity in early-type galaxies, thepossible dependence of their radio emission on basic optical parameters,such as the absolute magnitude, the central velocity dispersion sigma,and the mean surface brightness mu is explored. A sample of 743 E and SOgalaxies is used which is based on three independent radio surveys ofoptically selected galaxies with virtually complete information onmagnitudes, morphological types, redshift distances, diameters, andradio fluxes. For both E and SO galaxies, only the absolute magnitudeappears to be directly related to the radio activity, while sigma and mudo not. Also, a significant dependence of the apparent flattening onradio power is confirmed for E galaxies. Some relevant implications ofthese results are discussed.
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Spectroscopy and photometry of elliptical galaxies. III - UBV aperture photometry, CCD photometry, and magnitude-related parameters
Photoelectric aperture photometry of nearly 2000 individual observationsof 449 elliptical galaxies combined with published measurements usingthe self-consistent UVB color catalog developed by Burstein et al.(1987) are presented. The data are placed on a standard magnitude andcolor system, and 'total' magnitudes and effective diameters are derivedby comparison with the standard elliptical magnitude growth curve. Agraphical representation of the standard growth curve and the residualsfrom it for each galaxy are given, and a new diameter measurement Dn ispresented which can be measured reliably for elliptical galaxies andserves as an accurate distance indicator when combined with centralvelocity dispersion. Individual magnitudes, surface brightnesses,effective diameters, and values of Dn are summarized for each galaxy incatalog form.
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A catalog of stellar velocity dispersions. I - Compilation and standard galaxies
A catalog of central stellar velocity dispersion measurements ispresented, current through June 1984. The catalog includes 1096measurements of 725 galaxies. A set of 51 standard galaxies is definedwhich consists of galaxies with at least three reliable, concordantmeasurements. It is suggested that future studies observed some of thesestandard galaxies in the course of their observations so that differentstudies can be normalized to the same system. Previous studies arecompared with the derived standards to determine relative accuracies andto compute scale factors where necessary.
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Dynamics of luminous galaxies. II - Surface photometry and velocity dispersions of brightest cluster members
The velocity dispersions for 46 galaxies and CCD surface photometry for27 galaxies presented furnish a greatly improved data set forinvestigation of the brightest galaxies in galaxy clusters. Thebrightest cluster members (BCMs) are noted to be substantially brighterthan predicted by such considerations as their velocity dispersions.Attention is given to the possibility that this may be a selectioneffect due to the spread of M at a given velocity dispersion; it isnevertheless shown that the observed distribution of luminosity excessdoes not correspond to a simple model for selection, unless theelliptical galaxy sample suffers a Malmquist bias of 0.4 mag. The BCMswith largest excess luminosity have the largest effective radii and thelowest surface brightness, as predicted by homologous merger models.
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Catalogue of central velocity dispersions of galaxies
A total of 880 measurements of velocity dispersions for 546 galaxieshave been compiled. These data have been used to look for biasesintroduced by the observational techniques and reduction procedures. Twomain effects have been corrected for, due to the reference and the slitwidth. A catalog of homogeneous data has been compiled, where the rawdata are corrected for these effects.
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CO emission from IRAS galaxies
The results of a search for CO emission in 20 galaxies in the IRAScirculars are presented. The observations were carried out using the14-m millimeter telescope of the Five College Radio AstronomyObservatory (FCRAO) at a half-power beam width of 45 arcsec. CO wasdetected in 10 of the galaxies, including Arp 220 and NGC 6240. A roughcorrelation was found between CO and 10-micron luminosities, although awide scatter was observed in the relation. The very luminous far-IRgalaxies Arp 220 and NGC 6240 contain 3 x 10 to the 10th solar mass ofH2, or a factor of 3 more molecular gas than was found in the luminousspiral galaxies NGC and M51. It is shown that if the far-IR emissionoriginated in a region much smaller than 45 arcsec, the surface densityof the molecular hydrogen in Arp 220 may exceed that observed in any Scgalaxy.
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Radio continuum emission of nearby elliptical galaxies Statistical properties
A sample of 123 elliptical galaxies is compiled from optically selectedsamples observed at 1.4 GHz with the Westerbork Synthesis RadioTelescope. The analysis of the sample properties confirms thecorrelation of the radio continuum emission with optical luminosity, gascontent and roundness, but no indications for the influence of theenvironment are found. These results are discussed in relation to thehypothesis that accretion of gas onto the galaxy center is responsiblefor the radio emission.
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DDO photometry and metallic abundances of E and SO galaxies and globular clusters of the LMC and SMC
Metallicity of 8 E and SO galaxies as well as that of red globulars ofthe LMC and SMC were obtained by means of DDO integrated photometrycalibrated with galactic globular clusters (Bica and Pastoriza, 1983;hereafter referred to as Paper I). A correction was obtained in order toreduce the colors of the galaxies to zero redshift. The relationmetallicity vs M~ for the galaxies is analyzed (adding to our sample theobservations of McClure and Van den Bergh, 1968; and Faber, 1973a). Forthe Magellanic Clouds we found metallicity ranging from intermediate topoor
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The absorption-line strengths if elliptical and S0 galaxies.
Not Available
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The absorption-line strengths of elliptical and S0 galaxies
A subset of Faber's (1973) ten-color system is used to measureabsorption line strengths (LS) and colors of five S0 galaxies, twoellipticals, and three globular clusters. These observations arecombined with Faber's in order to analyze LS and color variations amongold stellar populations. The LS index (Mg)0 is found to beuseful for the study of old stellar populations. This index iscalibrated in terms of Fe/H (solar) from -2.2 to -0.5 on the basis ofglobular clusters and is extended to approximately 0.3 by using Mould's(1978) theoretical calculations. It is shown that most S0's,ellipticals, and globular clusters define a tight relationship in a plotof (Mg)0 vs. (45 - 67)0 and that the principalphysical parameter varying along this relationship is most plausibly theaverage metallicity of the stellar population. The S0's and ellipticalswith known or suspected young stellar components are found to deviatefrom this relationship, along lines termed bluing vectors.
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A 5-GHz survey of bright Southern elliptical and S0 galaxies
The Parkes 64-m telescope has been used in a 5.0-GHz survey of 181Southern E and S0 galaxies from the Reference catalogue of brightgalaxies. Of the 39 detections above the nominal limit of 12 mJy, 15 arenew, several have radio spectra indicating membership in the activeclass, and two have shown intensity variations at centimeterwavelengths. The results of this survey combined with results fromearlier surveys of lower sensitivity suggest that only about 40 per centof the E/S0 galaxies in the Reference catalogue have a flux density at 5GHz exceeding 1 mJy.
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Bibliography on the structure of galaxies.
Not Available
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Variations in Spectral-Energy Distributions and Absorption-Line Strengths among Elliptical Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...179..731F&db_key=AST
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A Survey of Elliptical Galaxies at 6 CM
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....24..247E&db_key=AST
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