- ID:
- ivo://CDS.VizieR/J/A+A/535/A39
- Title:
- Radial velocity survey toward NGC 6253
- Short Name:
- J/A+A/535/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the most metal-rich open cluster of the Galaxy, NGC 6253 is a target of special interest in the search for extrasolar planets, the study of stellar populations, and the chemical/dynamical evolution of the Galactic disk. We present the results of two photometric campaigns and a VLT multi-epoch radial velocity survey toward the open cluster NGC 6253. We complement our analysis with photometric, proper motion, and radial velocity data available from previous studies of this cluster, and analyze three planetary candidates found in the field of NGC 6253.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/534/114
- Title:
- RASSCALS: X-ray and optical study
- Short Name:
- J/ApJ/534/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the ROSAT All-Sky Survey Center for Astrophysics Loose Systems (RASSCALS), the largest X-ray and optical survey of low-mass galaxy groups to date. We draw 260 groups from the combined Center for Astrophysics and Southern Sky Redshift Surveys, covering one-quarter of the sky to a limiting Zwicky magnitude of m_z_=15.5.
- ID:
- ivo://CDS.VizieR/J/A+A/461/397
- Title:
- RASS-SDSS galaxy cluster survey. V.
- Short Name:
- J/A+A/461/397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we consider a large sample of optically selected clusters, in order to elucidate the physical reasons for the existence of X-ray underluminous clusters. For this purpose we analyzed the correlations of the X-ray and optical properties of a sample of 137 spectroscopically confirmed Abell clusters in the SDSS database. We searched for the X-ray counterpart of each cluster in the ROSAT All Sky Survey. We find that 40% of our clusters have a marginal X-ray detection or remain undetected in X-rays. These clusters appear too X-ray faint on average for their mass as determined by velocity dispersion; i.e. they do not follow the scaling relation between X-ray luminosity and virial mass traced by the other clusters. On the other hand, they do follow the general scaling relation between optical luminosity and virial mass. We refer to these clusters as the X-ray-underluminous Abell clusters (AXU clusters, for short) and designate as "normal" the X-ray detected Abell systems. We separately examined the distributions and properties of the galaxy populations of the normal and the AXU clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/435/781
- Title:
- Redshifts of galaxies in 21 EIS cluster fields
- Short Name:
- J/A+A/435/781
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out an investigation of the properties of low redshift EIS clusters using both spectroscopy and imaging data. We present new redshifts for 738 galaxies in 21 ESO Imaging Survey (EIS) Cluster fields. We use the "gap"-technique to search for significant overdensities in redshift space and to identify groups/clusters of galaxies corresponding to the original EIS matched filter cluster candidates. In this way we spectroscopically confirm 20 of the 21 cluster candidates with a matched-filter estimated redshift z_MF_=0.2. We have now obtained spectroscopic redshifts for 34 EIS cluster candidates with z_MF_=0.2 (see also Hansen et al., 2002, Cat. <J/A+A/388/1>; Olsen et al., 2003, Cat. <J/A+A/409/439>. Of those we spectroscopically confirm 32 with redshifts ranging from z=0.064 to 0.283. We find that: 1) the velocity dispersions of the systems range from sigma_v_<=130km/s to sigma_v_=1200km/s, typical of galaxy groups to rich clusters; 2) richnesses corresponding to Abell classes R<=1; and 3) concentration indices ranging from C=0.2 to C=1.2. From the analysis of the colours of the galaxy populations we find that 53% of the spectroscopically confirmed systems have a "significant" red sequence. These systems are on average richer and have higher velocity dispersions. We find that the colour of the red sequence galaxies matches passive stellar evolution predictions.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1280
- Title:
- Redshifts of HRS galaxies
- Short Name:
- J/AJ/131/1280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 118 new optical redshifts for galaxies in 12 clusters in the Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the Australian National University at Siding Spring Observatory. After combining 42 previously unpublished redshifts with our new sample, we determine mean redshifts and velocity dispersions for 13 clusters in which previous observational data were sparse.
- ID:
- ivo://CDS.VizieR/J/ApJ/607/202
- Title:
- Redshift survey of nearby galaxy groups
- Short Name:
- J/ApJ/607/202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We constrain the mass profile and orbital structure of nearby groups and clusters of galaxies. Our method yields the joint probability distribution of the density slope n, the velocity anisotropy {beta}, and the turnover radius r_0_ for these systems. The measurement technique does not use results from N-body simulations as priors. We incorporate 2419 new redshifts (included here) in the fields of 41 systems of galaxies with z<0.04.
- ID:
- ivo://CDS.VizieR/J/A+A/381/105
- Title:
- Rotational velocities of A-type stars. I.
- Short Name:
- J/A+A/381/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Within the scope of a Key Programme determining fundamental parameters of stars observed by HIPPARCOS, spectra of 525 B8 to F2-type stars brighter than V=8 have been collected at ESO. Fourier transforms of several line profiles in the range 4200-4500{AA} are used to derive vsini from the frequency of the first zero. Statistical analysis of the sample indicates that measurement error is a function of vsini and this relative error of the rotational velocity is found to be about 6% on average. The results obtained are compared with data from the literature. There is a systematic shift from standard values from Slk_7_5, which are 10 to 12% lower than our findings. Comparisons with other independent vsini values tend to prove that those from Slettebak et al. (1975ApJS...29..137S) are underestimated. This effect is attributed to the presence of binaries in the standard sample of Slettebak et al. (1975ApJS...29..137S), and to the model atmosphere they used.
- ID:
- ivo://CDS.VizieR/J/AJ/130/968
- Title:
- SDSS-C4 cluster catalog
- Short Name:
- J/AJ/130/968
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the C4 Cluster Catalog, a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2, 2004AJ....128..502A) of the Sloan Digital Sky Survey (SDSS). The C4 cluster-finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects that have plagued previous optical cluster selection. The present C4 catalog covers ~2600deg^2^ of sky and ranges in redshift from z=0.02 to 0.17. The mean cluster membership is 36 galaxies (with measured redshifts) brighter than r=17.7, but the catalog includes a range of systems, from groups containing 10 members to massive clusters with over 200 cluster members with measured redshifts. The catalog provides a large number of measured cluster properties including sky location, mean redshift, galaxy membership, summed r-band optical luminosity (L_r_), and velocity dispersion, as well as quantitative measures of substructure and the surrounding large-scale environment. We use new, multicolor mock SDSS galaxy catalogs, empirically constructed from the {Lambda}CDM Hubble Volume (HV) Sky Survey output, to investigate the sensitivity of the C4 catalog to the various algorithm parameters (detection threshold, choice of passbands, and search aperture), as well as to quantify the purity and completeness of the C4 cluster catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/L15
- Title:
- SDSS-DR7 broad-line QSOs
- Short Name:
- J/ApJ/804/L15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd_) of the black hole (BH) accretion. Shen & Ho (2014Natur.513..210S) demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion {sigma}_*_ (hence, the BH mass via the M-{sigma}_*_ relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, {sigma}_*_ systematically decreases with increasing FeII strength, confirming that the Eddington ratio increases with FeII strength. We also found that at fixed luminosity and FeII strength, there is little dependence of {sigma}_*_ on the broad H{beta} FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.
- ID:
- ivo://CDS.VizieR/J/A+A/471/17
- Title:
- SDSS-DR4 nearby clusters global properties
- Short Name:
- J/A+A/471/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large surveys such as the Sloan Digital Sky Survey have made large amounts of spectroscopic and photometric data of galaxies available, thereby providing important information for studying galaxy evolution in dense environments. We have selected a sample of 88 nearby (z<0.1) galaxy clusters from the SDSS-DR4 with redshift information for the cluster members. In particular, we focus on the galaxy morphological distribution, the velocity dispersion profiles, and the fraction of blue galaxies in clusters. Cluster membership was determined using the available velocity information. We derived global properties for each cluster, such as their mean recessional velocity, velocity dispersion, and virial radii. Cluster galaxies were grouped into two families according to their u-r colours.
