http://arxiv.org/abs/1907.10476
Since several years ago, the search for multiple populations (MPs) in Galactic open clusters (OCs) has become a field of increasing interest, particularly to the light of the general knowledge that MPs are observed in relatively massive clusters (>= 5 10^4 Mo). I report here measurements of stellar parameters and abundances of 17 different chemical species, including light and iron-peak elements of the old open cluster NGC188, from the APOGEE DR14 database. I selected 15 bonafide cluster red giants that reveal an spread in [Na/Fe] of +-0.16 dex, caused by two different groups of measurements whose mean [Na/Fe] values differ by ~ 0.30 dex. A hint for a subtle anti-correlation with Al and TiII, which also show relative large [X/Fe] dispersions, is also seen in the data. However, [Na/Fe] abundances have been found to be typically affected by uncertainties of 0.16 dex. Furthermore, I directly compared the available spectra for stars with similar atmospheric parameters and it would seem that they look similar. Therefore, I warn users of large spectroscopic surveys to be extra careful when finding peculiar abundance results. Analysis pipelines that run in an unsupervised fashion may produce bad results which may not be noticed before publication.
A. Piatti
Thu, 25 Jul 19
25/72
Comments: 8 pages, 5 figures. Enlarged version of RNAAS Research Notes of the AAS 3, 104 (2019)
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