- ID:
- ivo://CDS.VizieR/J/AJ/137/4956
- Title:
- Globular clusters around NGC 1407
- Short Name:
- J/AJ/137/4956
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 1407 is the central elliptical in a nearby evolved group of galaxies apparently destined to become a galaxy cluster core. We use the kinematics of globular clusters (GCs) to probe the dynamics and mass profile of the group's center, out to a radius of 60kpc (~10 galaxy effective radii)-the most extended data set to date around an early-type galaxy. This sample consists of 172 GC line-of-sight velocities, most of them newly obtained using Keck/DEIMOS, with a few additional objects identified as dwarf-globular transition objects or as intragroup GCs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PAZh/33/403
- Title:
- Globular clusters as gravitational lenses
- Short Name:
- J/PAZh/33/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the SDSS catalog, we have found new close quasar-galaxy pairs. We analyze the radial distribution of quasars from pairs around galaxies of different types. We show that the quasars from pairs follow the density profile of halo globular clusters. This is new observational evidence that the quasars projected onto the halos of galaxies are magnified by gravitational lensing by halo globular clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/L27
- Title:
- Globular clusters in ACSVCS early-type galaxies
- Short Name:
- J/ApJ/773/L27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a determination of the two-dimensional shape parameters of the blue and red globular cluster systems (GCSs) in a large number of elliptical galaxies and lenticular galaxies (early-type galaxies, called ETGs). We use a homogeneous data set of the globular clusters in 23 ETGs obtained from the HST/ACS Virgo Cluster Survey. The position angles of both blue and red GCSs show a correlation with those of the stellar light distribution, showing that the major axes of the GCSs are well aligned with those of their host galaxies. However, the shapes of the red GCSs show a tight correlation with the stellar light distribution as well as with the rotation property of their host galaxies, while the shapes of the blue GCSs do much less. These provide clear geometric evidence that the origins of the blue and red globular clusters are distinct and that ETGs may have dual halos: a blue (metal-poor) halo and a red (metal-rich) halo. These two halos show significant differences in metallicity, structure, and kinematics, indicating that they are formed in two distinguishable ways. The red halos might have formed via dissipational processes with rotation, while the blue halos are through accretion.
- ID:
- ivo://CDS.VizieR/J/AJ/108/2087
- Title:
- Globular Clusters in Ellipticals
- Short Name:
- J/AJ/108/2087
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRI photometry for the globular cluster systems (GCS's) of ten elliptical and S0 galaxies in Virgo and Leo. We find that the V-I color (metallicity) distributions are quite different from galaxy to galaxy. One extreme is represented by NGC 4374 with a narrow, blue distribution. NGC 4472 has a very broad, uniform distribution in color, corresponding to -1.8 < [Fe/H] < +0.47. At the other extreme is NGC 4365, which is weighted towards red colors, and possibly has a peculiar luminosity function. We suggest that this variation of GCS metallicity depends on environment, with formation of high metallicity globular clusters inhibited in higher density environments. We compare color-color plots of the GCS's of these galaxies with the Milky Way GCS and with integrated isochrones. We find good agreement with the galaxies studied here except that the isochrones predict colors which are slightly too bright in the I band for metal-rich clusters. We also consider the radial GC color distributions in these galaxies. We find evidence for a V-I color gradient only in NGC 4374, in the sense of redder clusters toward the center of the galaxy but warn that possible systematic effects must be ruled out with the new data. Lastly, using the surface brightness fluctuation distances to these galaxies, we find supporting evidence for the universality of the globular cluster luminosity function.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/155
- Title:
- Globular clusters in five early-type galaxies
- Short Name:
- J/MNRAS/416/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present deep high-quality photometry of globular cluster systems (GCSs) belonging to five early-type galaxies, covering a range of mass and environment. Photometric data were obtained with the Gemini North and Gemini South telescopes in the filter passbands g', r' and i'. The combination of these filters with good seeing conditions allows an excellent separation between globular cluster (GC) candidates and unresolved field objects.
1386. Globular clusters in M87
- ID:
- ivo://CDS.VizieR/J/AJ/106/493
- Title:
- Globular clusters in M87
- Short Name:
- J/AJ/106/493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep integrated Washington CCD photometry of the extremely populous globular cluster system of NGC 4486 (M87) in Virgo. The metallicities of 407 of the best candidates with T1 < 22 have been estimated from the (C-T1) color. These values are internally precise to ~0.15dex and accurate to ~0.25dex. The mean metallicity of the globular clusters is [Fe/H] = -0.86dex, with a formal standard error of the mean of 0.03dex but a more realistic uncertainty of about 0.2dex. This value is higher than that of the corresponding means of the globular clusters in the Galaxy and M31, but similar to those of the globular clusters in NGC 1399 and NGC 5128, as expected from the relative parent galaxy luminosities. Approximately 10% of the clusters exceed solar abundance, similar to the case for the globular clusters in NGC 1399 and NGC 5128. As found by Couture et al. [ApJS, 73, 671 (1990)], there is a large metallicity dispersion at any radius, with a sigma ~ 0.65dex. However, in contrast to their result and that of previous small-field CCD studies, the globular clusters display a marked gradient in both mean (M-T1) and (C-T1) color with galactocentric distance. The mean metallicity decreases by some 0.6dex over the radial extent of the cluster sample. This result is consistent with the early photographic study by Strom et al. [ApJ, 245, 416 (1981)]. The metallicity distribution function is remarkably similar to that of NGC 1399 found by Ostrov et al. [AJ, 105, 1762 (1993)] using the same technique. The two central cluster ellipticals show significant peaks at very similar metallicities, indicating similar formation and enrichment histories. We also find that this structure in the metallicity distribution function persists to radii where the halo light is dominated by the cD envelope.
- ID:
- ivo://CDS.VizieR/J/ApJS/150/367
- Title:
- Globular clusters in NGC 5128
- Short Name:
- J/ApJS/150/367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric and spectroscopic survey of the globular cluster (GC) system of NGC 5128 (Centaurus A), a galaxy whose proximity makes it an important target for early-type galaxy studies. We imaged three fields in UBVRI that extend 50 and 30kpc along the major and minor axes, respectively. We used both color and size information to develop efficient selection criteria for differentiating between star clusters and foreground stars. In total, we obtained new velocities for 138 globular clusters, nearly tripling the number of known clusters, and bringing the confirmed total in NGC 5128 to 215. We present a full catalog of all known GCs, with their positions, photometry, and velocities. In addition, we present catalogs of other objects observed, such as foreground stars, background galaxies, three Galactic white dwarfs, seven background QSOs, and 52 optical counterparts to known X-ray point sources. We also report an observation of the cluster [HGH92] G169, in which we confirm the existence of a bright emission line object. This object, however, is unlikely to be a planetary nebula, but may be a supernova remnant.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/123
- Title:
- Globular clusters in NGC 474 from CFHT obs.
- Short Name:
- J/ApJ/835/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters (GCs) are some of the most visible tracers of the merging and accretion histories of galaxy halos. Metal-poor GCs, in particular, are thought to arrive in massive galaxies largely through dry, minor merging events, but it is rare to see a direct connection between GCs and visible stellar streams. NGC 474 is a post-merger early-type galaxy with dramatic fine structures made of concentric shells and radial streams that have been more clearly revealed by deep imaging. We present a study of GCs in NGC 474 to better establish the relationship between merger-induced fine structure and the GC system. We find that many GCs are superimposed on visible streams and shells, and about 35% of GCs outside 3R_e,galaxy_ are located in regions of fine structure. The spatial correlation between GCs and fine structure is significant at the 99.9% level, which shows that this correlation is not coincidental. The colors of GCs on fine structures are mostly blue, and we also find an intermediate-color population that is dominant in the central region and that will likely passively evolve to have colors consistent with a traditional metal-rich GC population. The association of the blue GCs with fine structures is direct confirmation that many metal-poor GCs are accreted onto massive galaxy halos through merging events and that the progenitors of these mergers are sub-L^*^ galaxies.
- 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.
- 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.
