- ID:
- ivo://CDS.VizieR/J/A+A/446/773
- Title:
- GLMP sample of galactic OH/IR stars
- Short Name:
- J/A+A/446/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical and near-infrared finding charts taken from the DSS and 2MASS surveys of 94 IRAS sources selected from the GLMP catalogue, and accurate astrometry (~0.2") for most of them. Selection criteria were very red IRAS colours representative for OH/IR stars with optically thick circumstellar shells and the presence of variability according to the IRAS variability index (VAR>50). The main photometric properties of the stars in this `GLMP sample' are presented, discussed and compared with the correspondent properties of the `Arecibo sample' of OH/IR stars studied nearlier. We find that 37% of the sample (N=34) has no counterpart in the 2MASS, implying extremely high optical depths of their shells. Most of the sources identified in the 2MASS are faint (K>~8) and are of very red colour in the near-infrared, as expected. The brightest 2MASS counterpart (K=5.3mag) was found for IRAS18299-1705. Its blue colour H-K=1.3 suggests that IRAS18299-1705 is a post-AGB star. Few GLMP sources have faint but relatively blue counterparts. They might be misidentified field stars or stars that recently experienced a drop of their mass loss rates. The `GLMP sample' in general is made of oxygen-rich AGB stars, which are highly obscured by their circumstellar shells. They belong to the same population as the reddest OH/IR stars in the `Arecibo sample'.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/148/32
- Title:
- Globular cluster candidates in NGC 3115
- Short Name:
- J/AJ/148/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) g and z photometry and half-light radii R_h_ measurements of 360 globular cluster (GC) candidates around the nearby S0 galaxy NGC 3115. We also include Subaru/Suprime-Cam g, r, and i photometry of 421 additional candidates. The well-established color bimodality of the GC system is obvious in the HST/ACS photometry. We find evidence for a "blue tilt" in the blue GC subpopulation, wherein the GCs in the blue subpopulation get redder as luminosity increases, indicative of a mass-metallicity relationship. We find a color gradient in both the red and blue subpopulations, with each group of clusters becoming bluer at larger distances from NGC 3115. The gradient is of similar strength in both subpopulations, but is monotonic and more significant for the blue clusters. On average, the blue clusters have ~10% larger R_h_than the red clusters. This average difference is less than is typically observed for early-type galaxies but does match that measured in the literature for the Sombrero Galaxy (M104), suggesting that morphology and inclination may affect the measured size difference between the red and blue clusters. However, the scatter on the R_h_ measurements is large. We also identify 31 clusters more extended than typical GCs, which we term ultra-compact dwarf (UCD) candidates. Many of these objects are actually considerably fainter than typical UCDs. While it is likely that a significant number will be background contaminants, six of these UCD candidates are spectroscopically confirmed as NGC 3115 members. To explore the prevalence of low-mass X-ray binaries in the GC system, we match our ACS and Suprime-Cam detections to corresponding Chandra X-ray sources. We identify 45 X-ray-GC matches: 16 among the blue subpopulation and 29 among the red subpopulation. These X-ray/GC coincidence fractions are larger than is typical for most GC systems, probably due to the increased depth of the X-ray data compared to previous studies of GC systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/184
- Title:
- Globular cluster candidates in NGC4258
- Short Name:
- J/ApJ/835/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to explore the relationship between globular cluster total number, N_GC_, and central black hole mass, M_*_, in spiral galaxies, and compare it with that recently reported for ellipticals. We present results for the Sbc galaxy NGC 4258, from Canada-France-Hawaii Telescope data. Thanks to water masers with Keplerian rotation in a circumnuclear disk, NGC 4258 has the most precisely measured extragalactic distance and supermassive black hole mass to date. The globular cluster (GC) candidate selection is based on the (u*-i') versus (i'-Ks) diagram, which is a superb tool to distinguish GCs from foreground stars, background galaxies, and young stellar clusters, and hence can provide the best number counts of GCs from photometry alone, virtually free of contamination, even if the Galaxy is not completely edge-on. The mean optical and optical-near-infrared colors of the clusters are consistent with those of the Milky Way and M 31, after extinction is taken into account. We directly identify 39 GC candidates; after completeness correction, GC luminosity function extrapolation, and correction for spatial coverage, we calculate a total N_GC_=144+/-31_-36_^+38^ (random and systematic uncertainties, respectively). We have thus increased to six the sample of spiral galaxies with measurements of both M_*_ and N_GC_. NGC 4258 has a specific frequency S_N_=0.4+/-0.1 (random uncertainty), and is consistent within 2{sigma} with the N_GC_ versus M_*_ correlation followed by elliptical galaxies. The Milky Way continues to be the only spiral that deviates significantly from the relation.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A21
- Title:
- Globular cluster candidates in NGC253
- Short Name:
- J/A+A/611/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters (GCs) are key to our understanding of the Universe, as laboratories of stellar evolution, fossil tracers of the past formation epoch of the host galaxy, and effective distance indicators from local to cosmological scales. We analyze the properties of the sources in the NGC 253 with the aim of defining an up to date catalog of GC candidates in the galaxy. Given the distance of the galaxy, GCs in NGC 253 are ideal targets for resolved color-magnitude diagram studies of extragalactic GCs with next-generation diffraction limited ground-based telescopes. Our analysis is based on the science verification data of two ESO survey telescopes, VST and VISTA. Using ugri photometry from VST and JKs from VISTA, GC candidates were selected using as reference the morpho-photometric and color properties of spectroscopically confirmed GCs available in the literature. The strength of the results was verified against available archival HST/ACS data from the GHOSTS survey: all but two of the selected GC candidates appear as star clusters in HST footprints. The adopted GC selection leads to the definition of a sample of ~350 GC candidates. At visual inspection, we find that 82 objects match all the requirements for selecting GC candidates and 155 are flagged as uncertain GC candidate; however, 110 are unlikely GCs, which are most likely background galaxies. Furthermore, our analysis shows that four of the previously spectroscopically confirmed GCs, i.e., ~20% of the total spectroscopic sample, are more likely either background galaxies or high-velocity Milky Way stars. The radial density profile of the selected best candidates shows the typically observed r^1/4^-law radial profile. The analysis of the color distributions reveals only marginal evidence of the presence of color bimodality, which is normally observed in galaxies of similar luminosity. The GC luminosity function does not show the typical symmetry, mainly because of the lack of bright GCs. Part of the bright GCs missing might be at very large galactocentric distances or along the line of sight of the galaxy dusty disk. As an alternative possibility, we speculate that a fraction of low luminosity GC candidates might instead be metal-rich, intermediate age clusters, but fall in a similar color interval of old, metal-poor GCs. Defining a contaminant-free sample of GCs in extragalactic systems is not a straight forward exercise. Using optical and near-IR photometry we purged the list of GCs with spectroscopic membership and photometric GC candidates in NGC 253. Our results show that the use of either spectroscopic or photometric data only does not generally ensure a contaminant-free sample and a combination of both spectroscopy and photometry is preferred.
- ID:
- ivo://CDS.VizieR/J/other/NewA/88.J1607
- Title:
- Globular cluster NGC 6397 variable stars
- Short Name:
- J/other/NewA/88.
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a new time-series VI CCD photometry of the globular cluster NGC 6397, from which we obtained and analysed the light curves of 35 variables carefully identified in the cluster field. We assessed the membership of the variables with an astrometric analysis based on Gaia DR2 data. The cluster colour-magnitude diagram was differentially de- reddened and cleaned of non members, which allowed us to fit isochrones for [Fe/H]=-2.0dex in the range 13.0-13.5Gyr, for a mean reddening E(B-V)=0.19, and a distance of 2.5kpc. This distance was confirmed using the period-luminosity relation for the cluster's five SX Phoenicis variables (V10, V11, V15, V21, and V23) present among its blue stragglers, yielding 2.24+/-0.13kpc. We also modelled the light curves of four eclipsing binaries (V4, V5, V7, and V8), and gave the parameters of the systems; the contact binaries V7 and V8 have distances consistent with that of the cluster. NGC 6397 appears to harbour no RR Lyrae stars, being its horizontal branch remarkably blue, much like that of its analogous cluster, M10. To match the blue tail of the horizontal branch population, models of 0.64-0.66M_{sun}_ with mass loss at the RGB are required, indicating rather thin shell masses for horizontal branch stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/1317
- Title:
- Globular clusters in 3 early-type galaxies
- Short Name:
- J/MNRAS/420/1317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the age and metallicity distributions of bright globular clusters (GCs) in the candidate intermediate-age early-type galaxies NGC 3610, 584 and 3377 using a combination of new Gemini's Near InfraRed Imager and Spectrometer K'-band imaging and existing optical VI photometry from Hubble Space Telescope data.
- 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/MNRAS/405/2243
- Title:
- GMOS/WIYN spectroscopic catalogue
- Short Name:
- J/MNRAS/405/2243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest spectroscopic follow-up performed in SWIRE ELAIS-N1. We were able to determine redshifts for 289 extragalactic sources. The values of spectroscopic redshifts of the latter have been compared with the estimated values from our photometric redshift code with very good agreement between the two for both galaxies and quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A119
- Title:
- GOODS-Herschel North and South catalogs
- Short Name:
- J/A+A/533/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the deepest 100 to 500{mu}m far-infrared observations obtained with the Herschel Space Observatory as part of the GOODS-Herschel key program, and examine the infrared (IR) 3-500{mu}m spectral energy distributions (SEDs) of galaxies at 0<z<2.5, supplemented by a local reference sample from IRAS, ISO, Spitzer, and AKARI data. We determine the projected star formation densities of local galaxies from their radio and mid-IR continuum sizes.
