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|Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample|
This paper presents data on the ENEARc subsample of the larger ENEARsurvey of nearby early-type galaxies. The ENEARc galaxies belong toclusters and were specifically chosen to be used for the construction ofa Dn-σ template. The ENEARc sample includes newmeasurements of spectroscopic and photometric parameters (redshift,velocity dispersion, line index Mg2, and the angular diameterdn), as well as data from the literature. New spectroscopicdata are given for 229 cluster early-type galaxies, and new photometryis presented for 348 objects. Repeat and overlap observations withexternal data sets are used to construct a final merged catalogconsisting of 640 early-type galaxies in 28 clusters. Objectivecriteria, based on catalogs of groups of galaxies derived from completeredshift surveys of the nearby universe, are used to assign galaxies toclusters. In a companion paper, these data are used to construct thetemplate Dn-σ distance relation for early-typegalaxies, which has been used to estimate galaxy distances and derivepeculiar velocities for the ENEAR all-sky sample. Based on observationsat Complejo Astronomico El Leoncito, operated under agreement betweenthe Consejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; Cerro Tololo Inter-American Observatory,National Optical Astronomical Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation; the EuropeanSouthern Observatory (ESO), partially under the ESO-ON agreement; theFred Lawrence Whipple Observatory; the Observatório do Pico dosDias, operated by the Laboratório Nacional de Astrofísicaand the MDM Observatory at Kitt Peak.
|A catalogue of Mg_2 indices of galaxies and globular clusters|
We present a catalogue of published absorption-line Mg_2 indices ofgalaxies and globular clusters. The catalogue is maintained up-to-datein the HYPERCAT database. The measurements are listed together with thereferences to the articles where the data were published. A codeddescription of the observations is provided. The catalogue gathers 3541measurements for 1491 objects (galaxies or globular clusters) from 55datasets. Compiled raw data for 1060 galaxies are zero-point correctedand transformed to a homogeneous system. Tables 1, 3, and 4 areavailable in electronic form only at the CDS, Strasbourg, via anonymousftp 126.96.36.199. Table 2 is available both in text and electronic form.
|Galaxy clusters in the Perseus-Pisces region. I - Spectroscopic and photometric data for early-type galaxies|
We present new spectroscopic and photometric data for 137 early-typegalaxies in nine clusters and for a set of nearby standard galaxies. Ourspectroscopic data comprise radial velocities, central velocitydispersions, and magnesium line strength indices. We demonstrate thatour new velocity dispersion data can be brought into consistency withthe standard system, to an uncertainty of percent 0.01 dex. From R-bandCCD photometry, we derive the effective diameter, the mean surfacebrightness within the effective diameter, and an R-band diameterequivalent to the Dn parameter of Dressler et al. Internal comparisonsindicate an average error of 0.005 in each measurement of log Dn. Thephotometric data can be brought on to a system consistent with externaldata at the level of 0.5 per cent in distance.
|General study of group membership. II - Determination of nearby groups|
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
|Isophotal shapes of early-type galaxies. II - The Perseus Cluster|
We present the results of an isophotal shape analysis of a sample of 91early-type galaxies belonging to the Perseus Cluster, using CCD R and Vimages obtained in very good seeing conditions. This survey uncoversfine details in the structure of a large percentage of these objects,including disks, bars and even spiral arms, so that a large variety ofmorphological types is proposed. A very conservative upper limit for thepercentage of galaxies of the whole sample showing no deviations fromellipticity is given to be 20 percent. A lower limit for the detectionof bars among galaxies newly classified as S0's or spirals is about 30percent.
|The dynamics of rich clusters of galaxies. II - The Perseus cluster|
The dynamics of the Perseus cluster are analyzed using self-consistentequilibrium analytical models. Using existing data in the literatureplus new radial velocities reported here, composite surface density andvelocity dispersion profiles are derived. These profiles have beencompared with dynamical models described by Kent and Gunn (1982). Thebest fit suggest the presence of a significant degree of anisotropy inthe velocity distribution: galaxy orbits are constrained to pass withina radius of seven cluster radii, or 1.3 deg of the cluster center. ForHubble constant = 50, a core radius of 340 kpc 11 arcmin and a mass tovisual light ratio M/L = 300 are found. Using these results, X-rayobservations of the intracluster medium in Perseus are reanalyzed. Apreviously noted discrepancy between the observed temperature of the hotgas and the cluster velocity dispersion is reduced but not eliminated. Acooling accretion flow previously deduced to exist in this cluster isshown to extend to only about one-third of the cluster radius.
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