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1. The Open Cluster Chemical Abundances and Mapping Survey. IV. Abundances for 128 Open Clusters Using SDSS/APOGEE DR16

   https://doi.org/10.3847/1538-3881/ab77bc  

   Donor, John ; Frinchaboy, Peter M. ; Cunha, Katia ; O’Connell, Julia E. ; Prieto, Carlos Allende ; Almeida, Andrés ; Anders, Friedrich ; Beaton, Rachael ; Bizyaev, Dmitry ; Brownstein, Joel R. ; et al ( May 2020 , The Astronomical Journal)
2. The Open Cluster Chemical Abundances and Mapping Survey. V. Chemical Abundances of CTIO/Hydra Clusters Using The Cannon

   https://doi.org/10.3847/1538-3881/ac5835  

   Ray, Amy E. ; Frinchaboy, Peter M. ; Donor, John ; Chojnowski, S. D. ; Melendez, Matthew ( April 2022 , The Astronomical Journal)

   Open clusters are key chemical and age tracers of Milky Way evolution. While open clusters provide significant constraints on galaxy evolution, their use has been limited due to discrepancies in measuring abundances from different studies. We analyze medium-resolution (R∼ 19,000) Cerro Tololo Inter-American Observatory/Hydra spectra of giant stars in 58 open clusters using The Cannon to determine [Fe/H], [Mg/Fe], [Si/Fe], [Al/Fe], and [O/Fe]. This work adds an additional 55 primarily southern hemisphere open clusters calibrated to the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment DR16 metallicity system. This uniform analysis is compared to previous studies [Fe/H] measurements for 23 clusters and we present spectroscopic metallicities for the first time for 35 open clusters.

    

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3. CAPOS: the bulge Cluster APOgee Survey IV elemental abundances of the bulge globular cluster NGC 6558

   https://doi.org/10.1093/mnras/stad3178  

   González-Díaz, Danilo ; Fernández-Trincado, José G. ; Villanova, Sandro ; Geisler, Doug ; Barbuy, Beatriz ; Minniti, Dante ; Beers, Timothy C. ; Moni Bidin, Christian ; Mauro, Francesco ; Muñoz, Cesar ; et al ( October 2023 , Monthly Notices of the Royal Astronomical Society)

   This study presents the results concerning six red giant stars members of the globular cluster NGC 6558. Our analysis utilized high-resolution near-infrared spectra obtained through the CAPOS initiative (the APOgee Survey of Clusters in the Galactic Bulge), which focuses on surveying clusters within the Galactic Bulge, as a component of the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2). We employ the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) code to provide line-by-line elemental-abundances for Fe-peak (Fe, Ni), α-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z (Al), and the s-process element (Ce) for the four stars with high-signal-to-noise ratios. This is the first reliable measure of the CNO abundances for NGC 6558. Our analysis yields a mean metallicity for NGC 6558 of 〈[Fe/H]〉 = −1.15 ± 0.08, with no evidence for a metallicity spread. We find a Solar Ni abundance, 〈[Ni/Fe]〉 ∼ +0.01, and a moderate enhancement of α-elements, ranging between +0.16 and <+0.42, and a slight enhancement of the s-process element 〈[Ce/Fe]〉 ∼ +0.19. We also found low levels of 〈[Al/Fe]〉 ∼ +0.09, but with a strong enrichment of nitrogen, [N/Fe] > +0.99, along with a low level of carbon, [C/Fe] < −0.12. This behaviour of Nitrogen-Carbon is a typical chemical signature for the presence of multiple stellar populations in virtually all GCs; this is the first time that it is reported in NGC 6558. We also observed a remarkable consistency in the behaviour of all the chemical species compared to the other CAPOS bulge GCs of the same metallicity.

    

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4. WIYN Open Cluster Study 89. M48 (NGC 2548) 2: Lithium Abundances in the 420 Myr Open Cluster M48 from Giants through K Dwarfs* †

   https://doi.org/10.3847/1538-4357/acc5e3  

   Sun, Qinghui ; Deliyannis, Constantine P. ; Steinhauer, Aaron ; Anthony-Twarog, Barbara J. ; Twarog, Bruce A. ( July 2023 , The Astrophysical Journal)

   We consider WIYN/Hydra spectra of 329 photometric candidate members of the 420 Myr old open cluster M48 and report lithium detections or upper limits for 234 members and likely members. The 171 single members define a number of notable Li-mass trends, some delineated even more clearly than in Hyades/Praesepe: the giants are consistent with subgiant Li dilution and prior MS Li depletion due to rotational mixing. A dwarfs (8600–7700 K) have upper limits higher than the presumed initial cluster Li abundance. Two of five late A dwarfs (7700–7200 K) are Li-rich, possibly due to diffusion, planetesimal accretion, and/or engulfment of hydrogen-poor planets. Early F dwarfs already show evidence of Li depletion seen in older clusters. The Li–T_efftrends of the Li Dip (6675–6200 K), Li Plateau (6200–6000 K), and G and K dwarfs (6000–4000 K) are very clearly delineated and are intermediate to those of the 120 Myr old Pleiades and 650 Myr old Hyades/Praesepe, which suggests a sequence of Li depletion with age. The cool side of the Li Dip is especially well defined with little scatter. The Li–T_efftrend is very tight in the Li Plateau and early G dwarfs, but scatter increases gradually for cooler dwarfs. These patterns support and constrain models of the universally dominant Li depletion mechanism for FGK dwarfs, namely rotational mixing due to angular momentum loss; we discuss how diffusion and gravity-wave-driven mixing may also play roles. For late G/K dwarfs, faster rotators show higher Li than slower rotators, and we discuss possible connections between angular momentum loss and Li depletion.

    

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5. Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations

   https://doi.org/10.1103/PhysRevLett.126.141301  

   To, C. ; Krause, E. ; Rozo, E. ; Wu, H. ; Gruen, D. ; Wechsler, R. H. ; Eifler, T. F. ; Rykoff, E. S. ; Costanzi, M. ; Becker, M. R. ; et al ( April 2021 , Physical Review Letters)

   null (Ed.)