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The broadening of the main sequence in the open cluster M38

Griggio, M, Salaris, M, Bedin, LR and Cassisi, S (2023) The broadening of the main sequence in the open cluster M38. Monthly Notices of the Royal Astronomical Society, 523 (4). pp. 5148-5154. ISSN 0035-8711

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Our recent multiband photometric study of the colour width of the lower main sequence of the open cluster M37 has revealed the presence of a sizeable initial chemical composition spread in the cluster. If initial chemical composition spreads are common amongst open clusters, this would have major implications for cluster formation models and the foundation of the chemical tagging technique. Here, we present a study of the unevolved main sequence of the open cluster M38, employing Gaia DR3 photometry and astrometry, together with newly acquired Sloan photometry. We have analysed the distribution of the cluster’s lower main-sequence stars with a differential colour–colour diagram made of combinations of Gaia and Sloan magnitudes, like in the study of M37. We employed synthetic stellar populations to reproduce the observed trend of M38 stars in this diagram and found that the observed colour spreads can be explained simply by the combined effect of differential reddening across the face of the cluster and the presence of unresolved binaries. There is no need to include in the synthetic sample a spread of initial chemical composition as instead necessary to explain the main sequence of M37. Further photometric investigations like ours, as well as accurate differential spectroscopic analyses on large samples of open clusters, are necessary to understand whether chemical abundance spreads are common among the open cluster population.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2023 The Author[s] Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: astro-ph.SR; astro-ph.SR; astro-ph.GA; astro-ph.IM
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
SWORD Depositor: A Symplectic
Date Deposited: 26 Jun 2023 12:17
Last Modified: 10 Jul 2023 10:00
DOI or ID number: 10.1093/mnras/stad1754
URI: https://researchonline.ljmu.ac.uk/id/eprint/20066
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