- ID:
- ivo://CDS.VizieR/J/A+A/624/A25
- Title:
- HST WFC3 photometry of NGC 2419
- Short Name:
- J/A+A/624/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new deep imaging of the central regions of the remote globular cluster NGC 2419, obtained with the F343N and F336W filters of the Wide Field Camera 3 on board the Hubble Space Telescope. The new data are combined with archival imaging to constrain nitrogen and helium abundance variations within the cluster. We find a clearly bimodal distribution of the nitrogen-sensitive F336W-F343N colours of red giants, from which we estimate that about 55% of the giants belong to a population with about normal (field-like) nitrogen abundances (P1), while the remaining 45% belong to a nitrogen-rich population (P2). On average, the P2 stars are more He-rich than the P1 stars, with an estimated mean difference of {Delta}Y~=0.05, but the P2 stars exhibit a significant spread in He content and some may reach {Delta}Y~=0.13. A smaller He spread may also be present for the P1 stars. Additionally, stars with spectroscopically determined low Mg abundances ([Mg/Fe]<0) are generally associated with P2. We find the P2 stars to be slightly more centrally concentrated in NGC 2419 with a projected half-number radius of about 10% less than for the P1 stars, but the difference is not highly significant (p~=0.05). Using published radial velocities, we find evidence of rotation for the P1 stars, whereas the results are inconclusive for the P2 stars, which are consistent with no rotation as well as the same average rotation found for the P1 stars. Because of the long relaxation time scale of NGC 2419, the radial trends and kinematic properties of the populations are expected to be relatively unaffected by dynamical evolution. Hence, they provide constraints on formation scenarios for multiple populations, which must account not only for the presence of He spreads within sub-populations identified via CNO variations, but also for the relatively modest differences in the spatial distributions and kinematics of the populations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/140/631
- Title:
- HST WFC3/UVIS photometry of omega Cen core
- Short Name:
- J/AJ/140/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used archival multi-band Hubble Space Telescope observations obtained with the Wide Field Camera 3 in the UV-optical channel to present new important observational findings on the color-magnitude diagram (CMD) of the Galactic globular cluster omega Centauri. The ultraviolet (UV) WFC3 data have been coupled with available WFC/ACS optical-band data. The new CMDs, obtained from the combination of colors coming from eight different bands, disclose an even more complex stellar population than previously identified. This paper discusses the detailed morphology of the CMDs.
- ID:
- ivo://CDS.VizieR/J/PAZh/22/847
- Title:
- Identification and coordinates in M4
- Short Name:
- J/PAZh/22/847
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate equatorial coordinates have been determined for 54 variable stars in the globular cluster M 4=NGC 6121.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/509
- Title:
- Identification and coordinates in M5
- Short Name:
- J/PAZh/21/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate equatorial coordinates have been determined for 143 variable and suspected variable stars in the globular cluster M5=NGC 5904. For 28 stars, identifications with Kustner (1933VeUSB..26....1K) catalogue were found for the first time.
- ID:
- ivo://CDS.VizieR/J/PAZh/23/454
- Title:
- Identification and coordinates in M 53
- Short Name:
- J/PAZh/23/454
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Equatorial coordinates have been determined for 61 variables in the northern globular cluster M 53 and for 12 variables in the southern globular cluster NGC 2808 with accuracy sufficient for reliable identifications. A number of errors have been revealed in publications on variable starts in M 53.
- ID:
- ivo://CDS.VizieR/J/PAZh/20/693
- Title:
- Identification and coordinates in NGC 5272
- Short Name:
- J/PAZh/20/693
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Equatorial coordinates of variable stars in the globular cluster M3 (NGC 5272) and its nearest surroundings, mainly measured on a plate taken with The Zeiss-1000 telescope, are presented. Positions in a homogeneous system are presented for the first time for objects from the Catalogue of variable stars in globular clusters as well as for GCVS and NSV catalogue stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/374/399
- Title:
- Infrared star clusters with |b|<20{deg}
- Short Name:
- J/MNRAS/374/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used star density maps obtained from the Two-Micron All-Sky Survey (2MASS) to obtain a sample of star clusters in the entire Galactic Plane with |b|<20{deg}. A total of 1788 star cluster candidates are identified in this survey. Among those are 681 previously known open clusters and 86 globular clusters. A statistical analysis indicates that our sample of 1021 new cluster candidates has a contamination of about 50 per cent. Star cluster parameters are obtained by fitting a King profile to the star density. These parameters are used to statistically identify probable new globular cluster candidates in our sample. A detailed investigation of the projected distribution of star clusters in the Galaxy demonstrates that they show a clear tendency to cluster on spatial scales in the order of 12-25pc, a typical size for molecular clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A138
- Title:
- Intensity profiles for GC1 of M81
- Short Name:
- J/A+A/649/A138
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Researching the properties of the brightest globular cluster (referred to as GC1) in M 81 can provide a fossil record of the earliest stages of galaxy formation and evolution. The Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolour Sky Survey has carried out deep exposures of M 81. We derive the magnitudes in intermediate-band filters of the BATC system for GC1 and determine its age, mass, and structural parameters. GC1 was observed by BATC using 14 intermediate-band filters covering a wavelength range of 4000-10000{AA}. Based on photometric data in BATC and Two Micron All Sky Survey near-infrared JHKs filters, we constructed an extensive spectral energy distribution of GC1, spanning the wavelength range from 4000 to 20000{AA}. By comparing multicolour photometry with theoretical single stellar population synthesis models, we derived the age and mass of GC1. In addition, we obtained ellipticities, position angles, and surface brightness profiles for GC1 based on the images of deep observations with the Advanced Camera for Surveys on the Hubble Space Telescope. GC1 is better fitted by the Wilson model than by the King and Sersic models in the F606W filter, and it is better fitted by the Sersic model than by the King and Wilson models in the F814W filter. The 'best-fit' half-light radius of GC1 obtained here is 5.59pc, which is larger than the majority of normal globular clusters (GCs) of the same luminosity. The age and mass of GC1 estimated here are 13.0+/-2.90Gyr and 1.06-1.48x10^7^M_{sun}_, respectively. The Rh versus MV diagram shows that GC1 occupies the same area as extended star clusters. Therefore, we suggest that GC1 is more likely an accreted former nuclear star cluster than a classical GC similar to most of those in the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/143/87
- Title:
- IRAC photometry of massive M31 globular clusters
- Short Name:
- J/AJ/143/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several population synthesis models now predict integrated colors of simple stellar populations in the mid-infrared bands. To date, the models have not been extensively tested in this wavelength range. In a comparison of the predictions of several recent population synthesis models, the integrated colors are found to cover approximately the same range but to disagree in detail, for example, on the effects of metallicity. To test against observational data, globular clusters (GCs) are used as the closest objects to idealized groups of stars with a single age and single metallicity. Using recent mass estimates, we have compiled a sample of massive, old GCs in M31 which contain enough stars to guard against the stochastic effects of small-number statistics, and measured their integrated colors in the Spitzer/IRAC bands. Comparison of the cluster photometry in the IRAC bands with the model predictions shows that the models reproduce the cluster colors reasonably well, except for a small (not statistically significant) offset in [4.5]-[5.8]. In this color, models without circumstellar dust emission predict bluer values than are observed. Model predictions of colors formed from the V band and the IRAC 3.6 and 4.5{micro}m bands are redder than the observed data at high metallicities and we discuss several possible explanations. In agreement with model predictions, V-[3.6] and V-[4.5] colors are found to have metallicity sensitivity similar to or slightly better than V-K_s_.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/22
- Title:
- Iron abundance of Terzan 5 stars
- Short Name:
- J/ApJ/795/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new determinations of the iron abundance for 220 stars belonging to the stellar system Terzan 5 in the Galactic bulge. The spectra have been acquired with FLAMES at the Very Large Telescope of the European Southern Observatory and DEIMOS at the Keck II Telescope. This is by far the largest spectroscopic sample of stars ever observed in this stellar system. From this data set, a subsample of targets with spectra unaffected by TiO bands was extracted and statistically decontaminated from field stars. Once combined with 34 additional stars previously published by our group, a total sample of 135 member stars covering the entire radial extent of the system has been used to determine the metallicity distribution function of Terzan 5. The iron distribution clearly shows three peaks: a super-solar component at [Fe/H]=~0.25 dex, accounting for ~29% of the sample, a dominant sub-solar population at [Fe/H]=~-0.30 dex, corresponding to ~62% of the total, and a minor (6%) metal-poor component at [Fe/H]=~-0.8 dex. Such a broad, multi-modal metallicity distribution demonstrates that Terzan 5 is not a genuine globular cluster but the remnant of a much more complex stellar system.
