Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
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.
| 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.
| Environments of Redshift Survey Compact Groups of Galaxies
Redshift survey compact groups (RSCGs) are tight knots of N >= 3galaxies selected from the CfA2+SSRS2 redshift survey. The selection isbased on physical extent and association in redshift space alone. Wemeasured 300 new redshifts of fainter galaxies within 1 h^-1 Mpc of 14RSCGs to explore the relationship between RSCGs and their environments.Thirteen of 14 RSCGs are embedded in overdense regions of redshiftspace. The systems range from a loose group of five members to an Abellcluster. The remaining group, RSCG 64, appears isolated. RSCGs areisolated and distinct from their surroundings to varying degrees, as arethe Hickson compact groups. Among the 13 embedded RSCGs, three aredistinct from their general environments (RSCG 9, RSCG 11, and RSCG 85).
| 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 130.79.128.5. Table 2 is available both in text and electronic form.
| Stellar populations of cluster E and S0 galaxies
Spectral line index data for a sample of 290 E and S0 galaxies are usedto investigate the stellar populations of these galaxies. 250 of thegalaxies are members of 11 nearby clusters (cz_CMB<11500 km s^-1). Westudy how the stellar populations of the galaxies are related to thevelocity dispersions, the masses of the galaxies, and the clusterenvironment. This is done by establishing relations between theseparameters and the line indices Mg_2, and Hβ_G. Thedifference between the slope of the Mg_2-sigma relation and the slope ofthe -sigma relation indicates that the abundance ratio [Mg/Fe]is 0.3-0.4 dex higher for galaxies with velocity dispersions of 250 kms^-1 compared to galaxies with velocity dispersions of 100 km s^-1. Thisis in agreement with previous estimates by Worthey et al. The index is more strongly correlated with the projected cluster surfacedensity, rho_cluster, than with the galactic mass or the velocitydispersion. Earlier we found that the residuals for the Mg_2-sigmarelation depend on the cluster environment. Here we determine how boththe Mg_2 index and the index depend on the velocitydispersion and rho_cluster. Alternative explanations that could create aspurious environment dependence are discussed. No obvious alternativesare found. The environment dependence of the Mg_2-sigma relation issupported by data from Faber et al. The dependence on the environmentimplies that [Mg/Fe] decreases with increasing density, rho_cluster. Thedecrease in [Mg/Fe] is 0.1 dex over 2.5 dex in rho_cluster. We have alsostudied the extent to which the mass-to-light (M/L) ratios of thegalaxies are determined by the stellar populations. The M/L ratios arestrongly correlated with the indices Mg_2 and Hβ_G, while the index is only weakly correlated with the M/L ratio. Based oncurrent stellar population models, we find that it is not yet possibleto derive unique physical parameters (mean age, mean abundances, meanIMF, and fraction of dark matter) from the observables (line indices,velocity dispersion, mass, M/L ratio).
| 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.
| Spectroscopy for E and S0 galaxies in nine clusters
Central velocity dispersions, Mg_2 line indices and radial velocitiesfor 220 E and S0 galaxies are derived on the basis of intermediateresolution spectroscopy. Galaxies in the following clusters have beenobserved: Abell 194, Abell 539, Abell 3381, Abell 3574, S639, S753,Doradus, HydraI (Abell 1060) and Grm 15. For 151 of the galaxies, thevelocity dispersion has not previously been measured. 134 of the Mg_2determinations are for galaxies with no previous measurement. Thespectra cover either 500 or 1000A, centred on the magnesium triplet at5177A. The observations were obtained with the Boller & Chivensspectrograph at the ESO 1.5-m telescope and with the OPTOPUS, amulti-object fibre-fed B&C spectrograph, at the ESO 3.6-m telescope.The data are part of our ongoing study of the large-scale motions in theUniverse and the physical background for the Fundamental Plane. TheFourier fitting method was used to derive the velocity dispersions andradial velocities. The velocity dispersions have been corrected for theeffect of the size of the aperture. The correction was established onthe basis of velocity dispersion profiles available in the literature. Acomparison with results from Davies et al. shows that the derivedcentral velocity dispersions have an rms error of 0.036 in logsigma.There is no offset relative to the velocity dispersions from Davies etal. The offset relative to data from Lucey & Carter is-0.017+/-0.011 in logsigma, with our velocity dispersions being thesmallest. The velocity dispersions derived from the B&C and theOPTOPUS observations, as well as the velocity dispersions published byDavies et al., Dressler, Lucey & Carter and Lucey et al., can bebrought on a system consistent within 3 per cent. The Mg_2 line indiceshave been corrected for the size of the apertures, transformed to theLick system, and corrected for the effect of the velocity dispersion.From comparison with data from Davies et al. and from Faber, we findthat the rms error of Mg_2 is 0.013. Comparisons of the radialvelocities with data from the literature show that our determinationsare accurate to within ~=35 km s^-1. The accuracies reached for theseobservations are adequate for the study of the large-scale motions inthe Universe and for investigations of the Fundamental Plane.
| Multicolour CCD surface photometry for E and S0 galaxies in 10 clusters
CCD surface photometry for 232 E and S0 galaxies is presented. Thegalaxies are observed in Gunn r and Johnson B, or Gunn r and g. For 48of the galaxies surface photometry in Johnson U is also presented.Aperture magnitudes in Gunn nu are derived for half of the galaxies.Galaxies in the following clusters have been observed: Abell 194, Abell539, Abell 3381, Abell 3574, Abell S639, Abell S753, HydraI (Abell1060), DC2345-28, Doradus and Grm15. The data are part of our ongoingstudy of the large-scale motions in the Universe and the physicalbackground for the fundamental plane. We use a full model fittingtechnique for analysing the CCD images. This gives radial profiles oflocal surface brightness, colour, ellipticity and position angle. Theresiduals relative to the elliptical isophotes are describedquantitatively by Fourier expansions. Effective radius, mean surfacebrightness and total magnitude are derived by fitting a de Vaucouleursr^¼ growth curve. We have derived a characteristic radius r_nsimilar to the diameter D_n introduced by Dressler et al. The derivationof the effective parameters and of r_n takes the seeing into account. Weconfirm the results by Saglia et al. that the effects of the seeing canbe substantial. Seeing-corrected values of the effective parameters andr_n are also presented for 147 E and S0 galaxies in the Coma cluster.Colours, colour gradients and geometrical parameters are derived. Thephotometry is internally consistent within 0.016 mag. Comparison withthe photoelectric aperture photometry from Burstein et al. shows a meanoffset of 0.010 mag with an rms scatter of 0.034 mag. The globalphotometric parameters are compared with data from Faber et al., Luceyet al. and Lucey & Carter. These comparisons imply that the typicalrms errors are as follows - log r_n:+/-0.015 log r_e:+/-0.045m_T:+/-0.09 mag; _e:+/-0.16 mag. The rms error on thecombination log r_e-0.35_e which enters the fundamental planeis +/-0.020. Also, comparisons with data from Saglia et al. arepresented. The accuracy of the absolute photometry, as well as thederived parameters, makes the data suitable for our investigations ofthe fundamental plane and of the large-scale motions in the Universe.
| Molecular gas in powerful radio galaxies detected by IRAS
The present CO(J = 1 to 0) line survey of powerful radio galaxies hasled to the detection of five sources in eight IRAS-determined radiogalaxies. The range of the computed molecular gas masses is 1-7 timesthe H2 mass of the Milky Way and strikingly contrasts with the lowmolecular gas masses found in radio-quiet FIR-selected ellipticalgalaxies. These new CO observations lend support to the hypothesis thatpowerful radio galaxies result from disk galaxy collisions that evolveinto gas-rich, peculiar E/S0 galaxies in the course of their merging.
| Isophotal shapes of early-type galaxies. I - Elongated ellipticals
Forty-three very elongated elliptical galaxies were observed in directB, V, R CCD imaging with the 2-m telescope of Pic-du-Midi Observatoryand with the Canada-France-Hawaii telescope in fairly good seeingconditions. Five galaxies do not show an elliptical structure: threeclearly show spiral features and one is a dumbbell. The 38 othergalaxies were analyzed with an isophote-fitting procedure which allowsone to derive the deviations from pure ellipses in terms of thecoefficients of a Fourier series. The geometrical parameters of these 38elongated ellipticals are presented, with brief comments on theirpeculiarities.
| Linear clusters of galaxies - A194
New measurements for 160 redshifts and previous measurements for 108other redshifts are presented for galaxies within 5 deg of A194. Thegalaxy distribution in A194 is shown to be inconsistent with aspherically symmetric King model. A mass-to-light ratio is derived usingthe virial theorem which is lower than the mean for the groups in theCfA redshift survey (Huchra and Geller, 1982; Geller, 1984). Anonparametric test for galaxy-cluster alignment and a Chi-squared testare used to search for alignment of galaxy major axes with the axis ofA194. Evidence for neither luminosity segregation nor significantdifferences in the velocity or surface distributions of galaxies as afunction of morphological type is found.
| A survey of galaxies in the field of A194
The galaxies in the field of the cluster Abell 194 have been surveyedusing glass plate copies of the Palomar Observatory Sky Survey. Thedistribution in the sky of the diameter-limited galaxy sample has aposition angle of 128 deg and an axial ratio of 0.72. These measurementssuggest that the line of bright galaxies at the cluster center could bea bar of an overall larger filamentary structure, as in a barred spiralgalaxy. Although no statistically significant deviation from random isfound, the galaxy position-angle distribution shows a tendency to lineup along the central bright galaxy line and at right angles to it. Thelatter direction coincides with the position angle determined for theentire sample. For disk galaxies, there is a statistically significantdeviation of the observed axial-ratio distribution from the BdVcomparison sample. An excess of edge-on galaxies and a deficiency ofgalaxies at intermediate axial ratios is found.
| Neutral hydrogen in isolated galaxies. IV - Results for the Arecibo sample
A standard sample for the comparison of the H I content of galaxies invarious intergalactic environments is presently defined by means ofobservations of 324 isolated galaxies lying in the declination rangeaccessible to the Arecibo 305-m telescope. Both mapping and single pointspectra are used to compute the integral properties of these galaxies.Neutral hydrogen was detected in 288 of the 324 galaxies surveyed, andit is noted that the optical diameter of a spiral disk is bettercorrelated with the hydrogen mass than the morphological type. When usedto define a measure of H I content, the isolated galaxy sample canpredict 'normalcy' with an accuracy that carries a standard error ofabout 0.20 in the log of the H I mass, if a dependence on disk size, aswell as type, is taken into account.
| A catalog of morphological types in 55 rich clusters of galaxies
Data are presented from a study of 55 rich clusters of galaxies. Thedata include positions, morphological types, estimated total magnitudes,bulge sizes, and ellipticities for about 6000 galaxies, as determinedfrom high scale photographic plates. Data reduction procedures aredescribed, and a brief analysis of cluster richness, which indicatesthat Abell richness classes are only rough indicators of total clustermembership, is included.
| Low-Dispersion Spectra of Galaxies III. Abell No. 194
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973PASP...85..104P&db_key=AST
| Spectra and Other Characteristics of Interconnected Galaxies and of Galaxies in Groups and in Clusters. III.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964ApJ...139..269Z&db_key=AST
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
Catàlegs i designacions:
|
INHABITED SKY
