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Searching for GC-like abundance patterns in young massive clusters II. - Results from the Antennae galaxies

Lardo, C and Cabrera-Ziri, I and Davies, B and Bastian, N (2017) Searching for GC-like abundance patterns in young massive clusters II. - Results from the Antennae galaxies. Monthly Notices of the Royal Astronomical Society, 468 (2). pp. 2482-2488. ISSN 0035-8711

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Abstract

The presence of multiple populations (MPs) with distinctive light element abundances is a widespread phenomenon in clusters older than 6 Gyr. Clusters with masses, luminosities, and sizes comparable to those of ancient globulars are still forming today. Nonetheless, the presence of light element variations has been poorly investigated in such young systems, even if the knowledge of the age at which this phenomenon develops is crucial for theoretical models on MPs. We use J-band integrated spectra of three young (7-40 Myr) clusters in NGC 4038 to look for Al variations indicative of MPs. Assuming that the large majority (>70%) of stars are characterised by high Al content - as observed in Galactic clusters with comparable mass; we find that none of the studied clusters show significant Al variations. Small Al spreads have been measured in all the six young clusters observed in the near-infrared. While it is unlikely that young clusters only show low Al whereas old ones display different levels of Al variations; this suggests the possibility that MPs are not present at such young ages at least among the high-mass stellar component. Alternatively, the fraction of stars with field-like chemistry could be extremely large, mimicking low Al abundances in the integrated spectrum. Finally, since the near-infrared stellar continuum of young clusters is almost entirely due to luminous red supergiants, we can also speculate that MPs only manifest themselves in low mass stars due to some evolutionary mechanism.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record C. Lardo, I. Cabrera-Ziri, B. Davies, N. Bastian; Searching for GC-like abundance patterns in young massive clusters II. - Results from the Antennae galaxies. Mon Not R Astron Soc 2017 stx628. doi: 10.1093/mnras/stx628 is available online at: http://dx.doi.org/10.1093/mnras/stx628
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA; astro-ph.SR
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 17 Mar 2017 12:06
Last Modified: 07 Sep 2017 16:40
DOI or Identification number: 10.1093/mnras/stx628
URI: http://researchonline.ljmu.ac.uk/id/eprint/6032

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