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|Redshift-Distance Survey of Early-Type Galaxies: Spectroscopic Data|
We present central velocity dispersions and Mg2 line indicesfor an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984had no previous measures. This sample contains the largest set ofhomogeneous spectroscopic data for a uniform sample of ellipticalgalaxies in the nearby universe. These galaxies were observed as part ofthe ENEAR project, designed to study the peculiar motions and internalproperties of the local early-type galaxies. Using 523 repeatedobservations of 317 galaxies obtained during different runs, the dataare brought to a common zero point. These multiple observations, takenduring the many runs and different instrumental setups employed for thisproject, are used to derive statistical corrections to the data and arefound to be relatively small, typically <~5% of the velocitydispersion and 0.01 mag in the Mg2 line strength. Typicalerrors are about 8% in velocity dispersion and 0.01 mag inMg2, in good agreement with values published elsewhere.
|Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry|
We present R-band CCD photometry for 1332 early-type galaxies, observedas part of the ENEAR survey of peculiar motions using early-typegalaxies in the nearby universe. Circular apertures are used to tracethe surface brightness profiles, which are then fitted by atwo-component bulge-disk model. From the fits, we obtain the structuralparameters required to estimate galaxy distances using theDn-σ and fundamental plane relations. We find thatabout 12% of the galaxies are well represented by a pure r1/4law, while 87% are best fitted by a two-component model. There are 356repeated observations of 257 galaxies obtained during different runsthat are used to derive statistical corrections and bring the data to acommon system. We also use these repeated observations to estimate ourinternal errors. The accuracy of our measurements are tested by thecomparison of 354 galaxies in common with other authors. Typical errorsin our measurements are 0.011 dex for logDn, 0.064 dex forlogre, 0.086 mag arcsec-2 for<μe>, and 0.09 for mRC,comparable to those estimated by other authors. The photometric datareported here represent one of the largest high-quality and uniformall-sky samples currently available for early-type galaxies in thenearby universe, especially suitable for peculiar motion studies.Based on observations at Cerro Tololo Inter-American Observatory (CTIO),National Optical Astronomy Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation (NSF);European Southern Observatory (ESO); Fred Lawrence Whipple Observatory(FLWO); and the MDM Observatory on Kitt Peak.
|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 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.
|The components of mid- and far-infrared emission from S0 and early-type shell galaxies|
The IRAS database has been used to study detections of about 150early-type elliptical and S0 galaxies exhibiting a shell structure. Nostrong evidence for the expected enhancement of either star formationrates or heating of the interstellar medium is found. It is suggestedthat for some of the sample galaxies either a contribution from warmdust surrounding evolved stars or emission from an active nucleus may besignificant.
|Spectra of shell ellipticals - Redshifts, velocity dispersions and evidence for recent nuclear star formation|
Nuclear spectra are presented for 100 of the galaxies in the Malin andCarter (1983) catalog. Redshifts and velocity dispersions are given forsome of the galaxies. It is found that about 10 percent of the samplegalaxies have colors, absolute magnitudes, and spectra characteristic ofthe poststarburst galaxies in high reshift clusters. It is suggestedthat the more distant poststarburst galaxies may have undergone mergeror accretion events.
|Radio emission from shell elliptical galaxies|
A subset of the Malin & Carter catalogue of 'shell ellipticalgalaxies' has been surveyed at 20 and 6 cm with the VLA. Forty-two percent of the galaxies were detected, down to a 6-cm flux density limit ofabout 0.6 mJy. This detection rate does not differ significantly from anormal population of mixed elliptical and S0 galaxies. Most of the radiodetections, which are sources coincident with the galaxy nuclei, areunresolved by the C-array and so have angular sizes of less than 3arcsec. The sample contains objects with a wide variety of opticalappearances, suggesting that shell galaxies are not a homogenoeus classwith uniform physical characteristics.
|Southern Galaxy Catalogue.|
|A catalog of elliptical galaxies with shells|
We present a catalog of 137 elliptical galaxies south of -17 deg declination which exhibit shell or ripple features at large distances from the galaxy or in the outer envelope. Some of these galaxies show similar features in the inner envelope when suitable high resolution plate material is examined. Very few of the galaxies are associated with radio sources. We discuss the environment of shell galaxies, and the proportion of ellipticals which have these features. It appears that about half of the galaxies with shells are isolated and most of the rest are members of small groups. We discuss several individual examples which appear to be typical of this class of galaxy, and others which probably illustrate an evolutionary sequence.
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