- ID:
- ivo://CDS.VizieR/J/AJ/143/14
- Title:
- Lick indices of M31 globular clusters
- Short Name:
- J/AJ/143/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present absorption line indices measured in the integrated spectra of globular clusters both from the Galaxy and from M31. Our samples include 41 Galactic globular clusters, and more than 300 clusters in M31. The conversion of instrumental equivalent widths into the Lick system is described, and zero-point uncertainties are provided. Comparison of line indices of old M31 clusters and Galactic globular clusters suggests an absence of important differences in chemical composition between the two cluster systems. In particular, CN indices in the spectra of M31 and Galactic clusters are essentially consistent with each other, in disagreement with several previous works. We reanalyze some of the previous data, and conclude that reported CN differences between M31 and Galactic clusters were mostly due to data calibration uncertainties. Our data support the conclusion that the chemical compositions of Milky Way and M31 globular clusters are not substantially different, and that there is no need to resort to enhanced nitrogen abundances to account for the optical spectra of M31 globular clusters.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/415/123
- Title:
- Lick line-index and photometry of globular clusters
- Short Name:
- J/A+A/415/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains Lick line-index and photometric measurements of extragalactic globular clusters in seven early-type galaxies (NGC 1380, 2434, 3115, 3379, 3585, 5846, and 7192) with different morphological types (E/S0) located in field and group/cluster environments. High-quality spectra were taken with the FORS2 instrument at ESO's Very Large Telescope. ~50% of our data allows an age resolution {Delta}t/t~0.3 and a metallicity resolution ~0.25-0.4dex, depending on the absolute metallicity. Globular cluster candidates are selected from deep B, V, R, I, K FORS2/ISAAC photometry with 80-100% success rate inside one effective radius. Using combined optical/near-infrared colour-colour diagrams we present a method to efficiently reduce fore-/background contamination down to <~10%.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A103
- Title:
- Light curves for variables in 5 clusters
- Short Name:
- J/A+A/573/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the analysis of time-series observations from 2013 and 2014 of five metal rich ([Fe/H]>-1) globular clusters: NGC6388, NGC6441, NGC6528, NGC6638, and NGC6652. The data have been used to perform a census of the variable stars in the central parts of these clusters. The observations were made with the electron multiplying CCD (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile, and they were analysed using difference image analysis (DIA) to obtain high-precision light curves of the variable stars. It was possible to identify and classify all of the previously known or suspected variable stars in the central regions of the five clusters. Furthermore, we were able to identify, and in most cases classify 48, 49, 7, 8, and 2 previously unknown variables in NGC 6388, NGC 6441, NGC 6528, NGC 6638, and NGC 6652, respectively. Especially interesting is the case of NGC 6441, for which the variable star population of about 150 stars has been thoroughly examined by previous studies, including a Hubble Space Telescope study. In this paper we are able to present 49 new variable stars for this cluster, of which one (possibly two) are RR Lyrae stars, two are W Virginis stars, and the rest are long period semi-regular or irregular variables on the red giant branch. We have also detected the first double mode RR Lyrae in the cluster.
- ID:
- ivo://CDS.VizieR/J/other/PDDO/1.511
- Title:
- Light curves of M9 variables
- Short Name:
- J/other/PDDO/1.5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Time-series photographic photometry for the variable stars in M9.
- ID:
- ivo://CDS.VizieR/J/other/MmSAI/31.187
- Title:
- Light curves of 12 variables in NGC 6229
- Short Name:
- J/other/MmSAI/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Periods and light curves of 12 variable stars of the globular cluster NGC 6229 have been determined. The photographic magnitudes are given for 4 other variables. Observations were obtained at the Asiago observatory, in the years 1956-57-58.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1447
- Title:
- Light curves of variable stars in {omega} Cen
- Short Name:
- J/AJ/133/1447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a variable star catalog of an extensive ground-based wide-field variability survey in the globular cluster omega Centauri. Using the Australian National University 40 inch (1m) telescope at Siding Spring Observatory, the cluster was observed with a 52'x52' (0.75deg^2^) field for 25 nights, from 2003 May 2 to May 27. A total of 187 variable stars were identified in the field, 81 of which are new discoveries. This work comprises the widest field variability survey yet undertaken for this cluster. Here we present the V+R light curves and preliminary analysis of the detected variable stars, comprising 58 eclipsing binaries, 69 RR Lyrae stars, 36 long-period variables (P>=2days), and 24 miscellaneous pulsators including 15 SX Phoenicis stars and two type II Cepheids.
- ID:
- ivo://CDS.VizieR/J/AJ/156/6
- Title:
- Light element abundances of RGB & AGB stars in M10
- Short Name:
- J/AJ/156/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CN and CH band measurements for 137 red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster M10. Our measurements come from low-resolution spectroscopy taken with the Hydra spectrograph on the WIYN-3.5 m telescope. We use these measurements to identify two populations of stars within the cluster, CN-normal and CN-enhanced, and find that in our sample 60% of stars are CN-enhanced. Our large sample allows us to conduct a detailed analysis on the carbon and nitrogen abundances and the radial distribution of each population separately. Our analysis of the radial dependence shows that each population has the same radial distribution in the cluster, which is likely due to the cluster being dynamically evolved. We also compare our results to other methods of classifying multiple populations in globular clusters such as the Na-O anti-correlation and the HST pseudo-color-magnitude diagrams. We find that these three methods of identifying multiple populations are in good agreement with each other for M10 and all lead to an estimate of the fraction of second-generation stars approximately equal to 60%. Among AGB stars, when classified by the CN band, there appears to be a lack of second-generation stars when compared to the RGB stars. However, when classified by [N/Fe], we find a similar 60% of AGB stars in the second generation. Finally, we use the measured carbon and nitrogen abundances in RGB stars to study the change of each element with magnitude as stars evolve up the RGB, comparing the results to globular clusters of similar metallicity, M3 and M13.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1314
- Title:
- Line list for seven target PAndAS clusters
- Short Name:
- J/MNRAS/448/1314
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed chemical abundances are presented for seven M31 outer halo globular clusters (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated light spectra taken with the Hobby-Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS) - this paper presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal poor ([Fe/H]< -1.5), {alpha}-enhanced (though they are possibly less {alpha}-enhanced than Milky Way stars at the 1{sigma} level), and show signs of star-to-star Na and Mg variations. The other three globular clusters (H10, H23, and PA17) are more metal rich, with metallicities ranging from [Fe/H]=-1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way globular clusters, and other M31 clusters, H10 and PA17, have moderately low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17's high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud. None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW cloud, and PA53 and PA56 may be associated with the eastern cloud.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3319
- Title:
- Line list for the NGC 1851 stars
- Short Name:
- J/MNRAS/446/3319
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the C+N+O abundance sum in red giant stars in two Galactic globular clusters, NGC 1851 and NGC 6752. NGC 1851 has a split subgiant branch which could be due to different ages or C+N+O content while NGC 6752 is representative of the least complex globular clusters. For NGC 1851 and NGC 6752, we obtain average values of A(C+N+O)=8.16+/-0.10 ({sigma}=0.34) and 7.62+/-0.02 ({sigma}=0.06), respectively. When taking into account the measurement errors, we find a constant C+N+O abundance sum in NGC 6752. The C+N+O abundance dispersion is only 0.06 dex, and such a result requires that the source of the light element abundance variations does not increase the C+N+O sum in this cluster. For NGC 1851, we confirm a large spread in C+N+O. In this cluster, the anomalous RGB has a higher C+N+O content than the canonical RGB by a factor of 4 (~0.6 dex). This result lends further support to the idea that the two subgiant branches in NGC 1851 are roughly coeval, but with different CNO abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A55
- Title:
- Line list from Pal 13 sample stars
- Short Name:
- J/A+A/632/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At a Galactocentric distance of 27kpc, Palomar 13 is an old globular cluster (GC) belonging to the outer halo. We present a chemical abundance analysis of this remote system from high-resolution spectra obtained with the Keck/HIRES spectrograph. Owing to the low signal-to-noise ratio of the data, our analysis is based on a coaddition of the spectra of 18 member stars. We are able to determine integrated abundance ratios for 16 species of 14 elements, of {alpha}-elements (Mg, Si, Ca, and Ti), Fe-peak (Sc, Mn, Cr, Ni, Cu, and Zn), and neutron-capture elements (Y and Ba). While the mean Na abundance is found to be slightly enhanced and halo-like, our method does not allow us to probe an abundance spread that would be expected in this light element if multiple populations are present in Pal 13. We find a metal-poor mean metallicity of -1.91+/-0.05 (statistical) +/-0.22 (systematic), confirming that Pal 13 is a typical metal-poor representative of the outer halo. While there are some differences between individual {alpha}-elements, such as halo-like Mg and Si versus the mildly lower Ca and Ti abundances, the mean [{alpha}/Fe] of 0.34+/-0.06 is consistent with the marginally lower {alpha} component of the halo field and GC stars at similar metallicity. We discuss our results in the context of other objects in the outer halo and consider which of these objects were likely accreted. We also discuss the properties of their progenitors. While chemically, Pal 13 is similar to Gaia-Enceladus and some of its GCs, this is not supported by its kinematic properties within the Milky Way system. Moreover, its chemodynamical similarity with NGC 5466, a purported progeny of the Sequoia accretion event, might indicate a common origin in this progenitor. However, the ambiguities in the full abundance space of this comparison emphasize the difficulties in unequivocally labeling a single GC as an accreted object, let alone assigning it to a single progenitor.
