- ID:
- ivo://CDS.VizieR/J/AJ/127/2674
- Title:
- Globular clusters in Sculptor group
- Short Name:
- J/AJ/127/2674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use CTIO 4m Mosaic II images taken with the Washington CM and Harris R filters to identify candidate globular clusters in the six major galaxies of the Sculptor group: NGC 45, 55, 247, 254, 300, and 7793. From follow-up spectroscopy with Hydra-CTIO, we find 19 new globular clusters in NGC 55, 247, 253, and 300, bringing the total number of known Sculptor group globular clusters to 36. The newly discovered clusters have spectroscopic ages consistent with those of old Milky Way globular clusters, and the majority are metal-poor.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/272/391
- Title:
- Globular clusters in the Magellanic Clouds
- Short Name:
- J/MNRAS/272/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report JHK results of observations of 12 globular clusters in the Large Magellanic Cloud (LMC), and present colour-magnitude diagrams down to K=16 (corresponding to absolute K~-2.6) for ~450 stars in these clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/87
- Title:
- Globular clusters of M60 with HST
- Short Name:
- J/ApJ/760/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present g and z photometry and size estimates for globular clusters (GCs) in the massive Virgo elliptical NGC 4649 (M60) using a five-pointing Hubble Space Telescope/Advanced Camera for Surveys mosaic. The metal-poor GCs show a monotonic negative metallicity gradient of -0.43+/-0.10dex per dex in radius over the full radial range of the data, out to ~24kpc. There is evidence for substantial color substructure among the metal-rich GCs. The metal-poor GCs have typical sizes ~0.4pc larger than the metal-rich GCs out to large galactocentric distances (>~20kpc), favoring an intrinsic explanation for the size difference rather than projection effects. There is no clear relation between half-light radius and galactocentric distance beyond ~15kpc, suggesting that the sizes of GCs are not generically set by tidal limitation. Finally, we identify ~20 candidate ultracompact dwarfs that extend down to surprisingly faint absolute magnitudes (M_z_~-8.5), and may bridge the gap between this class and "extended clusters" in the Local Group. Three of the brighter candidates have published radial velocities and can be confirmed as bona fide ultracompact dwarfs; follow-up spectroscopy will determine the nature of the remainder of the candidates.
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/1172
- Title:
- Globular Clusters of NGC 4278 in SLUGGS
- Short Name:
- J/MNRAS/436/1172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use multipointing Hubble Space Telescope Advanced Camera for Surveys and wide field Subaru Suprime-Cam imaging to study the globular cluster system of the L* elliptical galaxy NGC 4278. We have also obtained a handful of new globular cluster spectra with the Keck Deep Imaging Multi-Object Spectrograph. We determine the globular cluster surface density profile and use it to calculate the total number of globular clusters, finding the system to be slightly more populous than average for galaxies of its luminosity. We find clear evidence for bimodality in the globular cluster colour distribution and for a colour-magnitude relation in the blue subpopulation (a 'blue tilt'). We also find negative radial colour gradients in both colour subpopulations of equal strength which are similar in strength to those reported in other galaxies. The sizes of NGC 4278's globular clusters decrease with redder colours and increase with galactocentric radius. The ratio of the sizes of blue to red globular clusters is independent of galactocentric radius demonstrating that internal effects are responsible for the size difference with colour.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A37
- Title:
- 4 globular clusters RGB and AGB stars
- Short Name:
- J/A+A/603/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic studies have demonstrated that nearly all Galactic globular clusters (GCs) harbour multiple stellar populations with different chemical compositions. Moreover, colour-magnitude diagrams based exclusively on Stroemgrem photometry have allowed us to identify and characterise multiple populations along the RGB of a large number of clusters. In this paper we show for the first time that Stroemgren photometry is also very efficient at identifying multiple populations along the AGB, and demonstrate that the AGB of M3, M92, NGC362, NGC1851, and NGC6752 are not consistent with a single stellar population. We also provide a catalogue of RGB and AGB stars photometrically identified in these clusters for further spectroscopic follow-up studies. We combined photometry and elemental abundances from the literature for RGB and AGB stars in NGC6752 where the presence of multiple populations along the AGB has been widely debated. We find that, while the MS, SGB, and RGB host three stellar populations with different helium and light element abundances, only two populations of AGB stars are present in the cluster. These results are consistent with standard evolutionary theory.
- ID:
- ivo://CDS.VizieR/J/ApJ/559/812
- Title:
- Globular cluster system in M87
- Short Name:
- J/ApJ/559/812
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive database of kinematic, photometric, and positional information for 352 objects in the field of M87 (NGC 4486), the central giant elliptical galaxy in the Virgo Cluster; the majority of the tracers are globular clusters associated with that galaxy. New kinematic information comes from multislit observations with the Multi-Object Spectrograph (MOS) of the Canada-France-Hawaii Telescope (CFHT), an investigation that has added 96 new velocities to and confirmed many of the earlier values in a preexisting data set of 256 velocities published elsewhere. The photometry, consisting of magnitudes and colors in the Washington (T_1_, C-T_1_) system, is based on CCD observations made at the Cerro Tololo Inter-American Observatory (CTIO) and the Kitt Peak National Observatory (KPNO).
- ID:
- ivo://CDS.VizieR/J/ApJ/513/733
- Title:
- Globular cluster system in M87
- Short Name:
- J/ApJ/513/733
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 1057 globular cluster candidates in a WFPC2 image of the inner region of M87. The globular cluster luminosity function (GCLF) can be well fitted by a Gaussian profile with a mean value of m^0^_V_=23.67+/-0.07mag and {sigma}=1.39+/-0.06mag. The GCLF in five radial bins is found to be statistically the same at all points, showing no clear evidence of dynamical destruction processes based on the luminosity function (LF). Similarly, there is no obvious trend between the half-light radius of the clusters and the galactocentric distance. The core radius of the globular cluster density distribution is R_c_=56", considerably larger than the core of the stellar component (R_c_=6.8"). The mean color of the cluster candidates is V-I=1.09mag, which corresponds to an average metallicity of Fe/H=-0.74dex. The color distribution is bimodal everywhere, with a blue peak at V-I=0.95mag and a red peak at V-I=1.20mag. The red population is only 0.1mag bluer than the underlying galaxy, indicating that these clusters formed late in the metal-enrichment history of the galaxy and were possibly created in a burst of star/cluster formation 3-6Gyr after the blue population. We also find that both the red and the blue cluster distributions have a more elliptical shape (Hubble type E3.5) than the nearly spherical galaxy. The average half-light radius of the clusters is ~2.5pc, which is comparable to the 3pc average effective radius of the Milky Way clusters, although the red clusters are ~20% smaller than the blue ones.
- ID:
- ivo://CDS.VizieR/J/A+A/455/453
- Title:
- Globular Cluster System of NGC5846
- Short Name:
- J/A+A/455/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 5846 is a giant elliptical galaxy with a previously well studied globular cluster system (GCS), known to have a bimodal colour distribution with a remarkably high red fraction. Here we revisit the central galaxy regions searching for new globular cluster (GC) candidates, and measure magnitudes, colours and sizes for them. We also search for their X-ray counterparts. Methods: We use archival Hubble Space Telescope WFPC2 images, from which we modelled and subtracted the host light distribution to increase the available sample of GCs. We performed photometry on the central objects, and measured sizes and coordinates for the entire GC system known in this galaxy. Results: We detect two dozen previously unknown GC candidates in the central reg ions. Reliable sizes are obtained for about 60 GCs; their typical effective radii are in the range 3-5pc. The largest clusters are located in the central regions. We find 7 X-ray counterparts to GCs, most of them in the central region. They are among the most luminous X-ray sources in NGC 5846. They are also optically luminous, compact and belong to the red subpopulation. Conclusions: The GCS of NGC 5846 is composed of relatively luminous X-ray sources.
- ID:
- ivo://CDS.VizieR/J/PASP/109/883
- Title:
- Globular metallicity scale. I.
- Short Name:
- J/PASP/109/883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained 2640 CCD spectra with resolution ~4{AA} in the region 7250-9000{AA} for 976 stars lying near the red giant branches in color-magnitude diagrams of 52 Galactic globular clusters. Radial velocities of ~16km/s accuracy per star determined from the spectra are combined with other criteria to assess quantitative membership probabilities. Measurements of the equivalent widths of the infrared calcium triplet lines yield a relative metal-abundance ranking with a precision that compares favorably to other techniques. Regressions between our system and those of others are derived. Our reduction procedures are discussed in detail, and the resultant catalog of derived velocities and equivalent widths is presented. The metal abundances derived from these data will be the subject of a future paper. (c) Astronomical Society of the Pacific
2290. Globulars in M31
- ID:
- ivo://CDS.VizieR/J/AJ/114/1488
- Title:
- Globulars in M31
- Short Name:
- J/AJ/114/1488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep (V=~27) V- and I-band stellar photometry of G302 and G312, two globular star clusters in the halo of M31. These data were obtained using the Hubble Space Telescope's Wide Field/Planetary Camera 2. We find iron abundances of [Fe/H]=-1.85+/-0.12 for G302 and [Fe/H]=-0.56+/-0.03 for G312, consistent with spectroscopic measurements. The color-magnitude diagrams for each cluster show no evidence for an intermediate-aged population of stars, or a second parameter effect in the morphology of the horizontal branch. G302 shows no evidence for a color gradient but the inner regions of G312 are bluer than the outer regions. G312 shows no evidence of ellipticity or an extended halo of stars. G302 has a projected ellipticity of {epsilon}=0.195+/-0.012 with the projected major axis oriented towards the center of M31. G302 also shows evidence of an extended asymmetric stellar halo extending to at least twice the fitted Michie-King tidal radius. The amount of mass beyond the tidal radius of G302 is consistent with the stellar escape rates which have been predicted by N-body simulations of globular clusters in the Galactic tidal field. (c) 1997 American Astronomical Society.
