- ID:
- ivo://CDS.VizieR/VII/256
- Title:
- Groups of Galaxies from CfA2 Redshift Survey
- Short Name:
- VII/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains statistically homogeneous and physically well graunded groups of galaxies based on the CfA2 redshift survey (Cat. J/ApJS/121/287) in the area of space 1000km/s<=cz<=15000km/s, |bII|>=20{deg}. For identification of groups we used a modification of a friends of friends (FoF) method. Principles of friendship and definition of values of presented there free parameters described in Mahtessian (1988Afz....28..255M, 1997Ap.....40..285M). There are 1971 groups with 2 or more members, for a total of 6787 members (46.3%); 765 of the groups have 3 or more members with 4375 galaxies (28.1%). The others 8790 (56.4%) galaxies make a sample of "single" galaxies. The catalog includes group numbers, numbers of members, equatorial coordinates, Virgo-centric radial velocities, line-of-sight-velocity dispersions, integrated group luminosities, and relative quantity of false members.
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- ID:
- ivo://CDS.VizieR/J/AJ/154/96
- Title:
- Groups of galaxies from from SDSS-DR7
- Short Name:
- J/AJ/154/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the dependence of stellar population properties of galaxies on group dynamical stage for a subsample of the Yang catalog. We classify groups according to their galaxy velocity distribution into Gaussian (G) and Non-Gaussian (NG). Using two totally independent approaches, we have shown that our measurement of Gaussianity is robust and reliable. Our sample covers Yang's groups in the redshift range 0.03{<=}z{<=}0.1, with mass {>=}10^14^M_{Sun}_. The new method, called Hellinger Distance, to determine whether a group has a velocity distribution Gaussian or NG is very effective in distinguishing between the two families. NG groups present halo masses higher than the G ones, confirming previous findings. Examining the skewness and kurtosis of the velocity distribution of G and NG groups, we find that faint galaxies in NG groups are mainly infalling, for the first time, into the groups. We show that considering only faint galaxies in the outskirts; those in NG groups are older and more metal-rich than those in G groups. Also, examining the Projected Phase Space of cluster galaxies, we see that bright and faint galactic systems in G groups are in dynamical equilibrium-which does not seem to be the case in NG groups. These findings suggest that NG systems have a higher infall rate, assembling more galaxies that have experienced preprocessing before entering the group.
- ID:
- ivo://CDS.VizieR/VII/84A
- Title:
- Groups of Galaxies. III. The CfA Survey
- Short Name:
- VII/84A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains statistically homogeneous groups of galaxies based on the Harvard-Smithsonian Center for Astrophysics (CfA) redshift survey. Groups in the catalog are all density enhancements in redshift space of a factor greater than 20. All groups contain at least three members. There are 176 groups in the catalog and 102 groups have been identified in one or more previous studies. The catalog includes group numbers, numbers of members, equatorial coordinates, mean flow-corrected galactocentric velocities, line-of-sight-velocity dispersion, integrated group magnitudes, crossing times for the groups, and mean harmonic radii of the groups.
- ID:
- ivo://CDS.VizieR/VII/86A
- Title:
- Groups of Galaxies. I. Nearby Groups
- Short Name:
- VII/86A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains nearby groups of galaxies with outer number density enhancement greater than 20. The groups were searched using a whole sky catalog of 1312 galaxies brighter than mag 13.2 (B) with complete redshift information (Huchra et al. =1983ApJS...52...89H). Only groups containing more than two members are included. The catalogue includes equatorial coordinates, average radial velocities, and velocity dispersions for 92 nearby groups in the first file. A second file contains the results of a comparison between this catalog and de Vaucouleurs' (1975) catalog of nearby groups The Hubble constant was assumed 100km/s/Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/655/790
- Title:
- Groups of galaxies in 2MASS survey
- Short Name:
- J/ApJ/655/790
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of applying a percolation algorithm to the initial release of the Two Micron All Sky Survey Extended Source Catalog, using subsequently measured redshifts for almost all of the galaxies with K<11.25mag. This group catalog is based on the first near-IR all-sky flux-limited survey that is complete to |b|=5{deg}. We explore the dependence of the clustering on the length and velocity scales involved. The paper describes a group catalog, complete to a limiting redshift of 104km/s, created by maximizing the number of groups containing three or more members. A second catalog is also presented, created by requiring a minimum density contrast of {delta}{rho}/{rho}>=80 to identify groups. We identify known nearby clusters in the catalogs and contrast the groups identified in the two catalogs. We examine and compare the properties of the determined groups and verify that the results are consistent with the UZC-SSRS2 and northern CfA redshift survey group catalogs. The all-sky nature of the catalog will allow the development of a flow-field model based on the density field inferred from the estimated cluster masses.
- ID:
- ivo://CDS.VizieR/J/A+AS/130/341
- Title:
- Groups of Galaxies in PPS
- Short Name:
- J/A+AS/130/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large catalog of galaxy loose groups in the Southern Galactic Hemisphere, selected from the Perseus-Pisces redshift Survey (PPS). Particular care is taken in order to obtain group samples as homogeneous as possible to previously published catalogs. Groups are identified with the adaptive Friends-of-Friends (FoF) algorithm of Huchra & Geller (1982ApJ...257..423H), with suitable normalizations V_0_=350km/s and D_0_=0.231h.Mpc. As a necessary ingredient of FoF algorithms, we obtain the galaxy luminosity function (LF) for PPS. Its Schechter parameters ({alpha}=-1.15+/-0.15, M_*_=-19.3+/-0.1) are in good agreement with similar LF estimates from samples previously used to select groups. The LF normalizations {phi}_*_=0.02h^3^/Mpc^3^ appropriate for PPS yields a density threshold {delta}n/n~180 for the adopted D_0_, apparently rather different from the desired {delta}n/n~80 used in previous studies. We then consider several other link normalizations, and briefly discuss their effect on group properties. We suggest to replace the customarily adopted {delta}n/n parametrization with the more direct D_0_ parametrization. All our catalogs contain N_G_~200 groups, significantly more than in most previous studies where group samples were obtained from galaxy data sets of comparable quality to (but smaller extent than) PPS. The group properties are rather sensitive to the adopted D_0_ and V_0_, but vary little with different redshift corrections, redshift cut-off, and galaxy LF. Loose groups in PPS nicely trace the large scale structure (LSS) in the parent galaxy sample. Physical properties of groups in PPS and in other directly comparable samples are in good agreement. There seems to be a complex interplay among LSS features, FoF grouping procedure, and group properties.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A44
- Title:
- gr photometry of Sextans A and Sextans B
- Short Name:
- J/A+A/566/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of the stellar and HI structure of the dwarf irregular galaxies Sextans A and Sextans B, members of the NGC3109 association. We use newly obtained deep (r~26.5) and wide field g,r photometry to extend the Surface Brightness (SB) profiles of the two galaxies down to mu_V_~31.0mag/arcsec^2^. We find that both galaxies are significantly more extended than what previously traced with surface photometry, out to ~4kpc from their centers along their major axis. Older stars are found to have more extended distribution with respect to younger populations. We obtain the first estimate of the mean metallicity for the old stars in Sex B, from the color distribution of the Red Giant Branch, <[Fe/H]>=-1.6. The SB profiles show significant changes of slope and cannot be fitted with a single Sersic model. Both galaxies have HI discs as massive as their respective stellar components. In both cases the HI discs display solid-body rotation with maximum amplitude of ~50km/s (albeit with significant uncertainty due to the poorly constrained inclination), implying a dynamical mass ~10^9^~M_{sun}_, a mass-to-light ratio M/L_V_~25 and a dark to-barionic mass ratio of ~10. The distribution of the stellar components is more extended than the gaseous disc in both galaxies. We find that the main, approximately round-shaped, stellar body of Sex A is surrounded by an elongated low-SB stellar halo that can be interpreted as a tidal tail, similar to that found in another member of the same association (Antlia). We discuss these, as well as other evidences of tidal disturbance, in the framework of a past passage of the NGC3109 association close to the Milky Way, that has been hypothesized by several authors and is also supported by the recently discovered filamentary configuration of the association itself
- ID:
- ivo://CDS.VizieR/J/ApJ/803/63
- Title:
- gr photometry of stars in Kim 2
- Short Name:
- J/ApJ/803/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new, low-luminosity star cluster in the outer halo of the Milky Way. High-quality gr photometry is presented, from which a color-magnitude diagram is constructed, and estimates of age, [Fe/H], [{alpha}/Fe], and distance are derived. The star cluster, which we designate as Kim 2, lies at a heliocentric distance of ~105kpc. With a half-light radius of ~12.8pc and ellipticity of {epsilon}~0.12, it shares the properties of outer halo globular clusters, except for at higher metallicity ([Fe/H]~-1.0) and lower luminosity (M_v_~-1.5). These parameters are similar to those for the globular cluster AM 4, which is considered to be associated with the Sagittarius dwarf spheroidal galaxy. We find evidence of dynamical mass segregation and the presence of extra-tidal stars that suggests that Kim 2 is most likely a star cluster. Spectroscopic observations for radial-velocity membership and chemical abundance measurements are needed to further understand the nature of the object.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/1587
- Title:
- GRS/BGPS sources in Galactic Plane
- Short Name:
- J/MNRAS/431/1587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The line of sight through the Galactic plane between longitudes l=37.83{deg} and 42.50{deg} allows for the separation of Galactic Ring Survey molecular clouds into those that fall within the spiral arms and those located in the interarm regions. By matching these clouds in both position and velocity with dense clumps detected in the mm continuum by the Bolocam Galactic Plane Survey, we are able to look for changes in the clump formation efficiency (CFE), the ratio of clump to cloud mass, with Galactic environment. We find no evidence of any difference in the CFE between the interarm and spiral-arm regions along this line of sight. This is further evidence that, outside the Galactic Centre region, the large-scale structures of the Galaxy play little part in changing the dense, potentially star-forming structures within molecular clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A69
- Title:
- GSH 305+01-24 stellar content
- Short Name:
- J/A+A/562/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of OB stars along with that of H{alpha}, ^12^CO, dust infrared emission, and neutral hydrogen is carried out in order to provide a more complete picture of interactions of the young massive stars and the observed supershell GSH 305+01-24. The studied field is located between 299{deg}<= l<= 311{deg} and -5{deg}<=b<=7{deg}. The investigation is based on nearly 700 O-B9 stars with uvby{beta} photometry currently available. The derived stellar physical parameters were used to establish a homogeneous scale for the distances and extinction of light for major apparent groups and layers of foreground and background stars in Centaurus and study the interaction with the surrounding interstellar medium. The distance to the entire Centaurus star-forming complex is revised and a maximum of the OB-star distance distribution is found at 1.8+/-0.4 (r.m.s) kpc. The massive star component of GSH 305+01-24 is identified at about 85-90% completeness up to 11.5-12mag. The projected coincidence of the OB stars with the shell and the similarities between the shell's morphology and the OB-star distribution indicate a strong interaction of the stellar winds with the superbubble material. We demonstrate that these stars contribute a sufficient wind injection energy in order to explain the observed size and expansion velocity of the supershell. The derived stellar ages suggest an age gradient over the Coalsack Loop. A continuous star-formation might be taking place within the shell with the youngest stars located at its periphery and the open cluster NGC 4755 being the oldest. A layer of very young stars at 1kpc is detected and its connection to both GSH 305+01-24 and the foreground GSH 304-00-12 HI shells is investigated.