We analyse the properties of galaxy populations in the rich Abell cluster ABCG 209 at redshift z~0.21, on the basis of spectral classification of 102 member galaxies. We take advantage of available structural parameters to study separately the properties of bulge-dominated and disk-dominated galaxies. The star formation histories of the cluster galaxy populations are investigated by using line strengths and the 4000{AA} break, through a comparison to stellar population synthesis models. The dynamical properties of different spectral classes are examined in order to infer the past merging history of ABCG 209. The cluster is characterized by the presence of two components: an old galaxy population, formed very early (z_f>~3.5), and a younger (z_f>~1.2) population of infalling galaxies. We find evidence of a merger with an infalling group of galaxies occurred 3.5-4.5Gyr ago. The correlation between the position of the young H_delta-strong galaxies and the X-ray flux shows that the hot intracluster medium triggered a starburst in this galaxy population ~3Gyr ago.
We present new photometric and spectroscopic observations of objects in the field of the cluster of galaxies Abell 2218. The photometric survey, centered on the cluster core, extends to a field of about 4'x4'. It was performed in 5 bands (B, g, r, i and z filters). This sample, which includes 729 objects, is about three times larger than the survey made by Butcher and collaborator (Butcher et al., 1983ApJS...52..183B, Butcher & Oemler, 1984ApJ...285..426B) in the same central region of the field. Only 228 objects appear in both catalogues since our survey covers a smaller region.
Photometry and Spectroscopy of Elliptical Galaxies
Short Name:
VII/176A
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric and spectroscopic data are presented for a survey of the nearest and brightest elliptical galaxies. Distances, velocities relative to the cosmic rest frame, and residual velocities relative to a velocity-flow model are calculated for individual galaxies and groups. Information is provided on the selection and completeness of the target and observed samples. Both samples appear to be noticeably deeper in the north than in the south. A new diameter system for ellipticals is described that is easy to measure on survey prints and is a useful indicator of B_T_ magnitude.
Using a magnitude-limited, spectroscopic survey of the X-ray-luminous galaxy cluster MS 1054-03, we isolate 153 cluster galaxies and measure MS 1054's redshift and velocity dispersion to be z=0.8307+/-0.0004 and {sigma}_z_=1156+/-82km/s. The absorption-line, post-starburst ("E+A"), and emission-line galaxies, respectively, make up 63%+/-7%, 15%+/-4%, and 23%+/-4% of the cluster population. With photometry from HST ACS, we find that the absorption-line members define an exceptionally tight red sequence over a span of ~3.5mag in i775: their intrinsic scatter in (V606-i775) color is only 0.048+/-0.008, corresponding to a (U-B)z scatter of 0.041.
Results of detailed 3-colour photometry of the distant cluster 2158+0351 (z=0.445) are presented. The photometry was produced using the INVENTORY package. The Gunn g, r, i magnitudes were measureed, down to r = 23.5, with a typical error of 0.1mag.
We present V and I CCD photometry of suspected low surface brightness dwarf galaxies detected in a survey covering ~2.4 deg^2^ around the central region of the Dorado group of galaxies. The low surface brightness galaxies were chosen based on their sizes and magnitudes at the limiting isophote of 26V{mu}. The selected galaxies have magnitudes brighter than V~20 (MV~-11 for an assumed distance to the group of 17.2 Mpc), with central surface brightnesses {mu}_0_>22.5 Vmag.arcsec^-2^, scale lengths h>2", and diameters >=14" at the limiting isophote. Using these criteria, we identified 69 dwarf galaxy candidates. Four of them are large very low surface brightness galaxies that were detected on a smoothed image, after masking high surface brightness objects. Monte Carlo simulations performed to estimate completeness, photometric uncertainties and to evaluate our ability to detect extended low surface brightness galaxies show that the completeness fraction is, on average, >80% for dwarf galaxies with -17<MV<-10.5 and 22.5<{mu}_0_<25.5 Vmag.arcsec^-2^, for the range of sizes considered by us (D>=14"). The V-I colors of the dwarf candidates vary from -0.3 to 2.3 with a peak on V-I=0.98, suggesting a range of different stellar populations in these galaxies. The projected surface density of the dwarf galaxies shows a concentration toward the group center similar in extent to that found around five X-ray groups and the elliptical galaxy NGC 1132 studied by Mulchaey & Zabludoff (1999ApJ...514..133M), suggesting that the dwarf galaxies in Dorado are probably physically associated with the overall potential well of the group.
We present the data processing and analysis techniques we are using to determine the structural and photometric properties of galaxies in our Gemini/HST Galaxy Cluster Project sample. The goal of this study is to understand cluster galaxy evolution in terms of scaling relations and structural properties of cluster galaxies at redshifts 0.15<z<1.0. To derive parameters such as total magnitude, half-light radius, effective surface brightness, and Sersic n, we fit r^1/4^ law and Sersic function two-dimensional surface brightness profiles to each of the galaxies in our sample. Using simulated galaxies, we test how the assumed profile affects the derived parameters and how the uncertainties affect our Fundamental Plane results. A catalog of photometry and surface brightness profile parameters is presented for three of the clusters in our sample, RX J0142.0+2131, RX J0152.7-1357, and RX J1226.9+3332 at redshifts 0.28, 0.83, and 0.89, respectively.
We present a set of UBVRIzJHKs photometry for 745 J+H-band-selected objects in a 22.5'x29.2' region centered on the core of the Coma Cluster. This includes 516 galaxies and is at least 80% complete to H=16, with a spectroscopically complete sample of 111 cluster members (nearly all with morphological classification) for H<14.5. For each object we present total Kron (1980ApJS...43..305K) magnitudes and aperture photometry. As an example, we use these data to derive color-magnitude relations for Coma early-type galaxies, measure the intrinsic scatter of these relations and its dependence on galaxy mass, and address the issue of color gradients.
Photometric observations are presented for 8747 galaxies in the fields of 28 clusters with redshifts in the range 0.05<z<0.11 and spanning a wide range in Abell richness class. The primary motivation for this study is to provide a nearby sample of clusters whose galaxy populations can be used to provide an anchor point for evolutionary studies of cluster galaxy populations.
New results are presented of Arecibo observations in the 21 cm line of 765 galaxies with declinations between 15.5 deg and 21.5 deg, in the Pisces-Perseus supercluster zone. If considered independently on the neighboring parts of the sky, this region, to the South of the supercluster ridge, shows significantly less evidence of structure on large scales in excess of 30 Mpc, contrasting substantially with the characteristics of the declination zones immediately to the North.
