- ID:
- ivo://CDS.VizieR/J/AJ/149/204
- Title:
- Spectroscopy of 25 stars in M68
- Short Name:
- J/AJ/149/204
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present a detailed high-resolution spectroscopic study of post main sequence stars in the globular cluster (GC) M68. Our sample, which covers a range of 4000K in T_eff_, and 3.5dex in log(g), is comprised of members from the red giant, red horizontal, and blue horizontal branch, making this the first high-resolution GC study covering such a large evolutionary and parameter space. Initially, atmospheric parameters were determined using photometric as well as spectroscopic methods, both of which resulted in unphysical and unexpected T_eff_, log(g), {xi}_t_, and [Fe/H] combinations. We therefore developed a hybrid approach that addresses most of these problems, and yields atmospheric parameters that agree well with other measurements in the literature. Furthermore, our derived stellar metallicities are consistent across all evolutionary stages, with <[Fe/H]>=-2.42 ({sigma}=0.14) from 25 stars. Chemical abundances obtained using our methodology also agree with previous studies and bear all the hallmarks of GCs, such as a Na-O anti-correlation, constant Ca abundances, and mild r-process enrichment.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/726/L20
- Title:
- Spectroscopy of Terzan 5
- Short Name:
- J/ApJ/726/L20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the chemical abundance analysis of 33 red giant stars belonging to the complex stellar system Terzan 5. We confirm the discovery of two stellar populations with distinct iron abundances: a relatively metal-poor component with [Fe/H]=-0.25+/-0.07rms and another component with [Fe/H]=+0.27+/-0.04rms, exceeding in metallicity any known Galactic globular cluster (GC). The two populations also show different [{alpha}/Fe] abundance ratios. The metal-poor component has an average [{alpha}/Fe]=+0.34+/-0.06rms, consistent with the canonical scenario for rapid enrichment by core collapse supernovae (SNe). The metal-rich component has [{alpha}/Fe]=+0.03+/-0.04rms, suggesting that the gas from which it formed was polluted by both type II and type Ia SNe on a longer timescale. Neither of the two populations shows evidence of the [Al/Fe] over [O/Fe] anti-correlation that is typically observed in Galactic GCs. Because these chemical abundance patterns are unique, we propose that Terzan 5 is not a true GC, but a stellar system with a much more complex history of star formation and chemical enrichment.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/124
- Title:
- Spectroscopy on LMC clusters
- Short Name:
- J/ApJ/749/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of an ongoing program to measure detailed chemical abundances in nearby galaxies, we use a sample of young- to intermediate-age clusters in the Large Magellanic Cloud with ages of 10Myr-2Gyr to evaluate the effect of isochrone parameters, specifically core convective overshooting, on Fe abundance results from high-resolution, integrated light spectroscopy. In this work we also obtain fiducial Fe abundances from high-resolution spectroscopy of the cluster individual member stars. We compare the Fe abundance results for the individual stars to the results from isochrones and integrated light spectroscopy to determine whether isochrones with convective overshooting should be used in our integrated light analysis of young- to intermediate-age (10Myr-3Gyr) star clusters. We find that when using the isochrones from the Teramo group, we obtain more accurate results for young- and intermediate-age clusters over the entire age range when using isochrones without convective overshooting. While convective overshooting is not the only uncertain aspect of stellar evolution, it is one of the most readily parameterized ingredients in stellar evolution models, and thus important to evaluate for the specific models used in our integrated light analysis. This work demonstrates that our method for integrated light spectroscopy of star clusters can provide unique tests for future constraints on stellar evolution models of young- and intermediate-age clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/389/1150
- Title:
- Spitzer photometry of globulars in 2 galaxies
- Short Name:
- J/MNRAS/389/1150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spitzer IR Array Camera (IRAC) mid-infrared photometry is presented for the globular cluster (GC) systems of the NGC 5128 ('Centaurus A') and NGC 4594 ('Sombrero') galaxies. Existing optical photometric and spectroscopic are combined with this new data in a comprehensive optical-to-mid-IR colour catalogue of 260 GCs. Empirical colour-metallicity relationships are derived for all optical-to-mid-IR colour combinations.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A60
- Title:
- Star cluster formation in a tidal debris
- Short Name:
- J/A+A/628/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. We study star cluster formation in a tidal debris - including the vicinity of three tidal dwarf galaxies - in a massive gas dominated collisional ring around NGC 5291. These dwarfs have physical parameters which differ significantly from local starbursting dwarfs. They are gas-rich, highly turbulent, have a gas metallicity already enriched up to half-solar, and are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment. We use imaging from the Hubble Space Telescope using broadband filters covering the wavelength range from the near- ultraviolet to the near-infrared. We determine the masses and ages of the cluster candidates by using the spectral energy distribution- fitting code CIGALE, carefully considering age-extinction degeneracy effects on the estimation of the physical parameters. Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of about 40%, comparable to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies and have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However one may speculate that similar objects at higher redshift, with higher star formation rate, might form some of the long lived globular clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/157/12
- Title:
- Star clusters, associations, & candidates in the MW
- Short Name:
- J/AJ/157/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of Galactic star clusters, associations and candidates with 10978 entries. This multi-band catalog was constructed over 20 years, starting with visual inspections on the Digital Sky Survey and incremented with the 2MASS, WISE, VVV, Spitzer, and Herschel surveys. Large and small catalogs, as well as papers on individual objects have been systematically cross-identified. The catalog provides Galactic and equatorial coordinates, angular diameters, and chronologically ordered designations, making it simple to assign discoveries and verify how often the objects were cataloged by different authors, search methods, and/or surveys. Detection in a single band is the minimum constraint to validate an entry. About 3200 objects have measured parameters in the literature. A fundamental contribution of the present study is to present an additional ~7700 objects for the first analyses of nature, photometry, spectroscopy and structure. The present focus is not to compile or determine fundamental parameters, but to provide a catalog uniformly characterizing the entries. A major result is that now 4234 embedded clusters are cataloged, a factor of ~1.5 larger than open clusters. In addition to cross-identifications in different references and wavelength domains, we also communicate the discovery of 638 star clusters and similar objects. The present general catalog provides previously studied objects and thousands of additional entries in a homogeneous way, a timely contribution to Gaia-related works.
- ID:
- ivo://CDS.VizieR/VII/44B
- Title:
- Star Clusters & Associations II. Globular Clusters
- Short Name:
- VII/44B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is the complete bibliographical listing for globular clusters from the second edition of the "Catalogue of Star Clusters and Associations (CSCA)" edited by Alter et al. (1970), and the "Supplement to the CSCA" by Ruprecht et al. (1981). Thus, it covers the literature through 1973. The file "main" contains the original data: for each cluster, the first line contains the running number (GCL) followed by designations used by various authors; the second line contains the 1950 coordinates, the 50-yr precession, the galactic coordinates, the galactic direction cosines and the position on the POSS charts; the lines following provide the following parameters: YEAR: Year of the literature reference NAME: Author PUBLICATION: Reference AD: Apparent diameter of the cluster (arcmin) DIST: Distance of the cluster (pc) LD: Linear diameter of the cluster (pc) N: Number of stars studied CE: Color excess SP: Integrated spectrum RV: Radial velocity (km/s) MT: Total (integrated) magnitude NOTE: Notes The file "clusters" has been created from second lines; missing positions were filled with the help of the SIMBAD data-base <http://cdsweb.u-strasbg.fr/Simbad/html>.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/123
- Title:
- Star clusters in IC 10
- Short Name:
- J/ApJ/804/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey of star clusters in the halo of IC 10, a starburst galaxy in the Local Group, based on Subaru R-band images and NOAO Local Group Survey UBVRI images. We find five new star clusters. All of these star clusters are located far from the center of IC 10, while previously known star clusters are mostly located in the main body. Interestingly, the distribution of these star clusters shows an asymmetrical structure elongated along the east and southwest directions. We derive UBVRI photometry of 66 star clusters, including these new star clusters, as well as previously known star clusters. Ages of the star clusters are estimated from a comparison of their UBVRI spectral energy distribution with the simple stellar population models. We find that the star clusters in the halo are all older than 1Gyr, while those in the main body have various ages, from very young (several Myr) to old (>1Gyr). The young clusters (<10Myr) are mostly located in the H{alpha} emission regions and are concentrated on a small region at 2" in the southeast direction from the galaxy center, while the old clusters are distributed in a wider area than the disk. Intermediate-age clusters (~100 Myr) are found in two groups. One is close to the location of the young clusters and the other is at ~ 4" from the location of the young clusters. The latter may be related to past mergers or tidal interaction.
819. Star Clusters in M33
- ID:
- ivo://CDS.VizieR/J/ApJS/122/431
- Title:
- Star Clusters in M33
- Short Name:
- J/ApJS/122/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the discovery of 60 star clusters in 20 multiband Hubble Space Telescope (HST) WFPC2 fields in M33. The fields sample a variety of environments, from outer regions to spiral arms and central regions, as well as a range of galactocentric distances. The HST spatial resolution allowed us to penetrate the crowded, spiral arm regions of M33 yielding the first unbiased, representative sample of star clusters for this galaxy. We discuss the separation of clusters from stellar sources, and from other extended sources such as star-forming regions, H II regions, and supernova remnants. For the clusters we present multiband images and discuss morphology, location, and integrated photometry. Measured cluster colors and magnitudes are presented. The cluster density in our sample as a function of galactocentric distance yields an estimate of 690 total clusters in M33.
820. Star clusters in M31
- ID:
- ivo://CDS.VizieR/J/ApJS/177/174
- Title:
- Star clusters in M31
- Short Name:
- J/ApJS/177/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new survey of star clusters in the southwest field of the M31 disk based on the high-resolution Subaru Suprime-Cam observations is presented. The UBVRI aperture CCD photometry catalog of 285 objects (V<~20.5mag; 169 of them identified for the first time) is provided. Each object is supplemented with multiband color maps presented in the electronic edition of the Astrophysical Journal Supplement. Seventy-seven star cluster candidates from the catalog are located in the Hubble Space Telescope archive frames.
