Homogeneous analysis of globular clusters from the APOGEE survey with the BACCHUS code

Aims. We seek to provide abundances of a large set of light and neutron-capture elements homogeneously analyzed that cover a wide range of metallicity to constrain globular cluster (GC) formation and evolution models. Methods. We analyzed a large sample of 885 GCs giants from the SDSS IV-Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. We used the Cannon results to separate the red giant branch and asymptotic giant branch stars, not only allowing for a refinement of surface gravity from isochrones, but also providing an independent H-band spectroscopic method to distinguish stellar evolutionary status in clusters. We then used the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) to derive metallicity, microturbulence, macroturbulence, many light-element abundances, and the neutron-capture elements Nd and Ce for the first time from the APOGEE GCs data. Results. Our independent analysis helped us to diagnose issues regarding the standard analysis of the APOGEE DR14 for low-metallicity GC stars. Furthermore, while we confirm most of the known correlations and anticorrelation trends (Na-O, Mg-Al, C-N), we discover that some stars within our most metal-poor clusters show an extreme Mg depletion and some Si enhancement. At the same time, these stars show some relative Al depletion, displaying a turnover in the Mg-Al diagram. These stars suggest that Al has been partially depleted in their progenitors by very hot proton-capture nucleosynthetic processes. Furthermore, we attempted to quantitatively correlate the spread of Al abundances with the global properties of GCs. We find an anticorrelation of the Al spread against clusters metallicity and luminosity, but the data do not allow us to find clear evidence of a dependence of N against metallicity in the more metal-poor clusters. Conclusions. Large and homogeneously analyzed samples from ongoing spectroscopic surveys unveil unseen chemical details for many clusters, including a turnover in the Mg-Al anticorrelation, thus yielding new constrains for GCs formation/evolution models.Spanish Ministry of Economy and Competitiveness (MINECO) [SEV-2015-0548]; MINECO [AYA-2017-88254-P]; Premium Postdoctoral Research Program of the Hungarian Academy of Sciences; Hungarian NKFI Grants of the Hungarian National Research, Development and Innovation Office [K-119517]; Crafoord Foundation; Stiftelsen Olle Engkvist Byggmastare; Ruth och Nils-Erik Stenbacks stiftelse; Chilean Centro de Excelencia en Astrofisica y Tecnologias Afines (CATA) BASAL grant [AFB-170002]; Direccion de Investigacion y Desarrollo de la Universidad de La Serena through the Programa de Incentivo a la Investigacion de Academicos (PIA-DIDULS); Physics Frontier Center/JINA Center for the Evolution of the Elements (JINA-CEE) - US National Science Foundation [PHY 14-30152]; Ministry of Economy and Competitiveness; FEDER funds [IACA13-3E-2493]; Alfred P. Sloan Foundation; U.S. Department of Energy Office of Science; Center for High-Performance Computing at the University of Utah; Brazilian Participation Group; Carnegie Institution for Science; Carnegie Mellon University; Chilean Participation Group; French Participation Group; Harvard-Smithsonian Center for Astrophysics; Instituto de Astrofisica de Canarias; Johns Hopkins University; Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo; Korean Participation Group; Lawrence Berkeley National Laboratory; Leibniz Institut fur Astrophysik Potsdam (AIP); Max-Planck-Institut fur Astronomie (MPIA Heidelberg); Max-Planck-Institut fur Astrophysik (MPA Garching); Max-Planck-Institut fur Extraterrestrische Physik (MPE); National Astronomical Observatories of China; New Mexico State University; New York University; University of Notre Dame; Observatorio Nacional/MCTI; Ohio State University; Pennsylvania State University; Shanghai Astronomical Observatory; United Kingdom Participation Group; Universidad Nacional Autonoma de Mexico; University of Arizona; University of colourado Boulder; University of Oxford; University of Portsmouth; University of Utah; University of Virginia; University of Washington; University of Wisconsin; Vanderbilt University; Yale UniversityOpen access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu