- ID:
- ivo://CDS.VizieR/J/MNRAS/409/1281
- Title:
- Old star clusters in the FSR catalogue
- Short Name:
- J/MNRAS/409/1281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the old star clusters in the sample of cluster candidates from the Froebrich, Scholz & Raftery (FSR, 2007, Cat. J/MNRAS/374/399) list. Based on photometry from the Two-Micron All-Sky Survey, we generated decontaminated colour-magnitude and colour-colour diagrams to select a sample of 269 old stellar clusters. This sample contains 63 known globular clusters, 174 known open clusters and 32 so far unclassified objects. Isochrone fitting has been used to homogeneously calculate the age, distance and reddening to all clusters.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/389/1924
- Title:
- Old stellar systems (globulars to ellipticals)
- Short Name:
- J/MNRAS/389/1924
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elliptical galaxies and globular clusters (GCs) have traditionally been regarded as physically distinct entities due to their discontinuous distribution in key scaling diagrams involving size, luminosity and velocity dispersion. Recently this distinctness has been challenged by the discovery of stellar systems with mass intermediate between those of GCs and dwarf ellipticals (such as ultracompact dwarfs and dwarf galaxy transition objects). Here we examine the relationship between the virial and stellar mass for a range of old stellar systems, from GCs to giant ellipticals, and including such intermediate-mass objects (IMOs). Improvements on previous work in this area include the use of (i) near-infrared magnitudes from the Two Micron All Sky Survey (2MASS), (ii) aperture corrections to velocity dispersions, (iii) homogeneous half-light radii and (iv) accounting for the effects of non-homology in galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A76
- Title:
- Omega Cen candidates RAVE-selected
- Short Name:
- J/A+A/583/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using six-dimensional phase-space information from the Fourth Data release of the RAdial Velocity Experiment (RAVE) over the range of Galactic longitude 240{deg}<l<360{deg} and VLSR<-239km/s, we computed orbits for 329 RAVE stars that were originally selected as chemically and kinematically related to Omega Centauri. The orbits were integrated in a Milky-Way-like axisymmetric Galactic potential, ignoring the effects of the dynamical evolution of Omega Centauri due to the tidal effects of the Galaxy disk on the cluster along time. We also ignored secular changes in the Milky Way potential over time. In a Monte Carlo scheme, and under the assumption that the stars may have been ejected with velocities greater than the escape velocity (V_rel_>V_esc,0_) from the cluster, we identified 15 stars as having close encounters with Omega Centauri: (i) 8 stars with relative velocities V_rel_<200km/s may have been ejected ~200Myr ago from Centauri; (ii) another group of 7 stars were identified with high relative velocity V_rel_>200km/s during close encounters, and it seems unlikely that they were ejected from Omega Centauri. We also confirm the link between J131340.4-484714 as a potential member of Omega Centauri, and probably ejected ~2.0Myr ago, with a relative velocity V_rel_~80km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/108/1350
- Title:
- Omega Cen FUV photometry
- Short Name:
- J/AJ/108/1350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present far-ultraviolet images of the globular cluster {omega} Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620{AA} to a limiting UV magnitude of 16.4 in the central 24' diameter region of the field and a limit of 15.6 over the remainder of the 40' diameter field. Over 1400 of these sources are matched with stars on a Stroemgren u band CCD frame obtained with the CTIO 0.9m telescope to produce a (far-UV, u) color-magnitude diagram. Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000K. A large number of "extreme HB" stars are found hotter than a conspicuous break in the HB at Te~16000K. There is also a significant population of stars above the HB, the brightest of which is 4mag brighter than the HB. Most of the hotter of these appear to be "AGB-manque" or "Post-Early Asymptotic Giant Branch" stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with Te>~50000K, which are hotter than zero-age HB stars with envelope masses of 0.003M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/114/1087
- Title:
- Omega Cen radial velocities
- Short Name:
- J/AJ/114/1087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a catalog of the mean radial velocities of 471 giant stars in the galactic globular cluster Omega Cen, the large majority of which are confirmed as cluster members. The typical uncertainty in the mean velocities is less than 1kms; a variability indicator and notes on chemical peculiarities are provided. In extension of earlier dynamical analyses of Omega Cen, based on part of the data presented here (Meylan & Mayor 1986A&A...166..122M; Meylan 1987A&A...184..144M; Meylan et al. 1995A&A...303..761M), a companion paper (Merritt et al. 1997AJ....114.1074M) rediscusses the subject, based on the full data set and a new theoretical approach, using nonparametric techniques.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A120
- Title:
- omega Cen RR Lyrae and SX Phoenicis stars
- Short Name:
- J/A+A/604/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The globular cluster {omega} Centauri (NGC 5139) hosts hundreds of pulsating variable stars of different types, thus representing a treasure trove for studies of their corresponding period-luminosity (PL) relations. Our goal in this study is to obtain the PL relations for RR Lyrae and SX Phoenicis stars in the field of the cluster, based on high-quality, well-sampled light curves in the near-infrared (IR). Observations were carried out using the VISTA InfraRed CAMera (VIRCAM) mounted on the Visible and Infrared Survey Telescope for Astronomy (VISTA). A total of 42 epochs in J and 100 epochs in K_S_ were obtained, spanning 352 days. Point-spread function photometry was performed using DoPhot and DAOPHOT crowded-field photometry packages in the outer and inner regions of the cluster, respectively. Based on the comprehensive catalog of near-IR light curves thus secured, PL relations were obtained for the different types of pulsators in the cluster, both in the J and K_S_ bands. This includes the first PL relations in the near-IR for fundamental-mode SX Phoenicis stars. The near-IR magnitudes and periods of Type II Cepheids and RR Lyrae stars were used to derive an updated true distance modulus to the cluster, with a resulting value of (m-M)_0_=13.708+/-0.035+/-0.10mag, where the error bars correspond to the adopted statistical and systematic errors, respectively. Adding the errors in quadrature, this is equivalent to a heliocentric distance of 5.52+/-0.27kpc.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A95
- Title:
- omega Cen RR Lyrae and Type II Cepheids
- Short Name:
- J/A+A/644/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The separation between RR Lyrae (RRLs) and type II Cepheid (T2Cs) variables based on their period is debated. Both types of variable stars are distance indicators, and we aim to promote the use of T2Cs as distance indicators in synergy with RRLs. We adopted new and existing optical and Near-Infrared (NIR) photometry of omega Cen to investigate several diagnostics (colour-magnitude diagram, Bailey diagram, Fourier decomposition of the light curve, amplitude ratios) for the empirical separation between Type II Cepheids (T2Cs) and RR Lyrae (RRLs). We also derived NIR period-luminosity relations and found a distance modulus of 13.65+/-0.07 (err.)+/-0.01 (sigma) mag, in agreement with the recent literature. We also found that RRLs and T2Cs obey the same PL relations in the NIR.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1395
- Title:
- omega Cen Spitzer photometry
- Short Name:
- J/AJ/135/1395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Spitzer Space Telescope imaging survey of the most massive Galactic globular cluster, {omega} Centauri, and investigate stellar mass loss at low metallicity and the intracluster medium (ICM). The survey covers approximately 3.2x the cluster half-mass radius at 3.6, 4.5, 5.8, 8, and 24um, resulting in a catalog of over 40000 point sources in the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/722/1373
- Title:
- {omega} Centauri giants abundances
- Short Name:
- J/ApJ/722/1373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present elemental abundances for 855 red giant branch (RGB) stars in the globular cluster Omega Centauri ({omega} Cen) from spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph. The sample includes nearly all RGB stars brighter than V=13.5 and spans {omega} Cen's full metallicity range. The heavy {alpha} elements (Si, Ca, and Ti) are generally enhanced by +/-0.3 dex and exhibit a metallicity-dependent morphology that may be attributed to mass and metallicity-dependent Type II supernova (SN) yields. The heavy {alpha} and Fe-peak abundances suggest minimal contributions from Type Ia SNe. The light elements (O, Na, and Al) exhibit >0.5 dex abundance dispersions at all metallicities, and a majority of stars with [Fe/H]>-1.6 have [O/Fe], [Na/Fe], and [Al/Fe] abundances similar to those in monometallic globular clusters, as well as O-Na, O-Al anticorrelations and the Na-Al correlation in all but the most metal-rich stars. A combination of pollution from intermediate-mass asymptotic giant branch stars and in situ mixing may explain the light element abundance patterns. A large fraction (27%) of {omega} Cen stars are O-poor ([O/Fe]<0) and are preferentially located within 5'-10' of the cluster center. The O-poor giants are spatially similar, located in the same metallicity range, and are present in nearly equal proportions to blue main-sequence stars. This suggests that the O-poor giants and blue main-sequence stars may share a common origin. [La/Fe] increases sharply at [Fe/H]>~-1.6, and the [La/Eu] ratios indicate that the increase is due to almost pure s-process production.
- ID:
- ivo://CDS.VizieR/J/A+A/400/521
- Title:
- Omega Cen XMM observations
- Short Name:
- J/A+A/400/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed the globular cluster Omega Cen (NGC 5139) with XMM-Newton on August 13th, 2001. The observation lasted 37ks and was performed with a medium filter. These tables list all the detected sources, and the spectral properties of selected sources within the field of view. For each source, we indicate its position, count rate, correlation with previous X-ray observation, and associated errors. For selected sources we also indicate its flux.
