Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/486/2477
- Title:
- Catalogue of members of NGC 6530
- Short Name:
- J/MNRAS/486/2477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The combination of precise radial velocities from multi-object spectroscopy and highly accurate proper motions from Gaia DR2 opens up the possibility for detailed 3D kinematic studies of young star-forming regions and clusters. Here, we perform such an analysis by combining Gaia-ESO Survey spectroscopy with Gaia astrometry for ~900 members of the Lagoon Nebula cluster, NGC 6530. We measure the 3D velocity dispersion of the region to be 5.35^+0.39^_-0.34_km/s, which is large enough to suggest the region is gravitationally unbound. The velocity ellipsoid is anisotropic, implying that the region is not sufficiently dynamically evolved to achieve isotropy, though the central part of NGC 6530 does exhibit velocity isotropy that suggests sufficient mixing has occurred in this denser part. We find strong evidence that the stellar population is expanding, though this is preferentially occurring in the declination direction and there is very little evidence for expansion in the right ascension direction. This argues against a simple radial expansion pattern, as predicted by models of residual gas expulsion. We discuss these findings in the context of cluster formation, evolution, and disruption theories.
- ID:
- ivo://CDS.VizieR/J/A+A/438/1163
- Title:
- Catalogue of Open Cluster Data (COCD)
- Short Name:
- J/A+A/438/1163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue is a result of studies of wide neighborhoods of 513 open clusters and 7 compact associations carried out in high precision homogeneous all sky catalogue ASCC-2.5 (Kharchenko, 2001, Cat. <I/280>). On the basis of data on about 33000 possible members (including about 10000 most probable ones) and homogeneous methods of cluster parameter determination the angular sizes of cluster cores and coronae, cluster heliocentric distances, mean proper motions, mean radial velocities and ages were established and collected in the COCD. These include cluster distances for 200 clusters, average cluster radial velocities for 94 clusters, and cluster ages for 195 clusters derived for the first time. Clusters in the catalogue are sorted by right ascension J2000 order. The Open Cluster Diagrams Atlas (OCDA) presents a set of open cluster diagrams used for the determination of parameters of 513 open clusters and 7 compact associations, and is intended to illustrate the quality of the constructed cluster membership (Kharchenko et al., 2004, Cat. <J/AN/425/740>), and the accuracy of the derived cluster parameters (this paper). Every diagram presents relation between various stellar data from all sky catalogue ASCC-2.5 (Kharchenko 2001, Cat. <I/280>) in area of the specific cluster. There are five diagrams provided for every cluster in the Atlas: the area map, the density profile, the vector point diagram, the magnitude equation diagram, and the color-magnitude diagram. The OCDA consists of 520 PostScript plots stored as gzipped files (i.e. one file per cluster).
- ID:
- ivo://CDS.VizieR/J/AN/340/386
- Title:
- Catalogue of spectroscopic binary candidate stars
- Short Name:
- J/AN/340/386
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the recently published Gaia second data release that includes measurements of the mean radial velocity of about 7.2 million stars, we performed a systematic comparison with other existing radial velocity catalogs to search for variations in the radial velocity measurements, with the goal that detected differences may indicate that these stars are possibly spectroscopic binary stars with only one visible component (SB1). We present a catalog of spectroscopic binary candidate stars containing 35246 stars, compiled to encourage follow-up observations obtaining spectra at different epochs of orbits of these stars to verify their binarity and to study these systems using radial velocity curves. Comparing the Gaia DR2 database with the K-M dwarf catalog, we found 16 stars that show radial velocity variations. In a comparison with the Pulkovo radial velocity catalog of Hipparcos stars, we identified a total of 539 SB1 candidate stars. In the largest radial velocity catalog available, the radial velocity experiment (RAVE) catalog, we found a total of 34691 stars that show radial velocity variations when compared to the Gaia DR2 data.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/407
- Title:
- CCD photometry & velocities of NGC 3680 stars
- Short Name:
- J/A+AS/118/407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new CCD photometry in the b and y colours of the Stroemgren uvby system for 310 stars in a 13'x13' field centered on the intermediate-age open cluster NGC 3680. Careful cross-checks indicate that previously published BV photometry of NGC 3680 is affected by random and/or systematic errors precluding its use in critical comparison with theoretical isochrone computations. Detailed notes on several individual stars are given. In addition, we present =~400 new photoelectric radial-velocity observations of 109 stars obtained with the CORAVEL scanner during the period 1988-1994. These data allow substantially complete identification of member and non-member stars in the field, and of spectroscopic binaries in both groups. Rotational velocities have also been derived for the programme stars, and our velocity variability criteria for stars of all rotations are described. The further astrophysical discussion of the data, including the definition of radial-velocity membership criteria, theoretical isochrone fitting, and the dynamical state of the cluster and the origin of its "bimodal turnoff", will appear in a separate paper (Nordstroem et al. 1996).
- ID:
- ivo://CDS.VizieR/J/AJ/106/831
- Title:
- cD clusters of galaxies. I.
- Short Name:
- J/AJ/106/831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results of a spectroscopic study of a sample of cD galaxy clusters. The goal of this program is to study the dynamics of the clusters, with emphasis on determining the nature and frequency of peculiar velocity cD galaxies. In this paper we present redshifts for 611 galaxies in the fields of the rich Abell clusters A193, A399, A401, A1795, A1809, A2063, and A2124. We discuss our data reduction techniques, and compare our derived velocities with previously published values. We find a frequency of emission line galaxies of ~6% in clusters, a factor of 2-3 less than the field.
- ID:
- ivo://CDS.VizieR/J/AJ/104/2078
- Title:
- cD Galaxy in Abell 2107
- Short Name:
- J/AJ/104/2078
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a program to study the kinematics of cD clusters of galaxies, we have measured the radial velocities of 75 galaxies in the field of Abell 2107. Sixty-eight of these galaxies are cluster members. The mean observed velocity of A2105 is 12335 +/- 86 km/s and the velocity dispersion is 672 [+67,-52] km/s. The cD galaxy has a peculiar velocity of 270 km/s with respect to the cluster mean. The distribution of velocities is well fitted by a Gaussian, but the velocities are spatially correlated. We have investigated simple two-body subcluster models for A2107, which are consistent with the observed data and account for the peculiar velocity of the cD galaxy. Alternatively, the spatial distribution of velocities is also consistent with rotation of a single cluster at the 98% confidence level. However, the pure rotation model fails to explain the peculiar velocity of the cD galaxy, which lies at the center of the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJS/170/95
- Title:
- Centaurus Cluster catalog
- Short Name:
- J/ApJS/170/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of all galaxies with V<=22.0 and R_iso_>3" within a 0.83deg^2^ region centered on the Centaurus Cluster (Abell 3526) at RA=12h48m, DE=-41{deg}18'. V-band total magnitudes along with other photometric parameters were obtained from the detection programs FOCAS and SExtractor and also from fitting curve-of-growth Sersic functions to the galaxy profiles. Central surface brightnesses, half-light radii, ellipticity, and position angles are presented, along with (B-V) aperture colors where B-band data were obtained. This work is part of a larger program to study the cluster-to-cluster variation in the faint end of the LF based on the study of eight clusters, including Centaurus. We discuss our data reduction methods in this paper. More detailed analyses and science results will be presented in subsequent papers.
- ID:
- ivo://CDS.VizieR/J/A+A/327/952
- Title:
- Centaurus cluster velocities
- Short Name:
- J/A+A/327/952
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the photometric survey of the inner region of the Centaurus cluster (Jerjen & Dressler, 1997, Cat. <J/A+AS/124/1>) we measured redshifts for a deep, surface brightness limited sample of galaxies using the MEFOS multifibre spectrograph at the ESO 3.6m telescope. With the new data set radial velocities for 120 centrally located cluster members become available which is equivalent to 78% of all known cluster galaxies in the region brighter than B_T_=18.5. The relevant aspect of this investigation is that new redshifts for 32 dwarf galaxies have been measured, rising the total number to 48. We investigate the prominent bimodal velocity distribution of Centaurus in more detail, discussing the very different characteristics of the velocity distributions for the main Hubble types E&S0, spirals, Im&BCD, and dE&dS0. The nucleated, bright dwarf ellipticals are the only galaxies with a Gaussian-like distribution centred at 3148+/-98km/s. The remarkable coincidence of this velocity with the mean velocity of Cen 30 and the redshift of NGC 4696 in particular strongly suggests a connection of the dE&dS0s to the gravitational centre of the Centaurus cluster and/or to the cluster dominant E galaxy. The application of statistical tests reveals the existence of a population dwarf galaxies bound to NGC 4696. The dynamical parameters for the two velocity components suggest that Cen 30 is the real Centaurus cluster whereas Cen 45 can only be a loosely bound group of galaxies. This conclusion is followed up with a type-mixture analysis. All results are fully consistent with the cluster-group scenario. Whether Cen 45 is merging with the cluster or is located in the close background remains unclear. We show that the poorness of Cen 45 represents an intrinsic problem which makes it difficult to approach this question.
- ID:
- ivo://CDS.VizieR/J/A+A/472/111
- Title:
- Centaurus Compact Object Survey
- Short Name:
- J/A+A/472/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our aim is to extend the investigations of ultra-compact dwarf galaxies (UCD) beyond the well studied Fornax and Virgo clusters. We measured spectroscopic redshifts of about 400 compact object candidates with 19.2<V<22.4mag in the central region of the Centaurus galaxy cluster (d=43Mpc), using 3 pointings with VIMOS@VLT. The luminosity range of the candidates covers the bright end of the globular cluster (GC) luminosity function and the luminosity regime of UCDs in Fornax and Virgo. Within the area surveyed, our completeness in terms of slit allocation is ~30%.