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Exploring the role of binarity in the origin of the bimodal rotational velocity distribution in stellar clusters

Kamann, S, Bastian, N, Usher, CG, Cabrera-Ziri, I and Saracino, S (2021) Exploring the role of binarity in the origin of the bimodal rotational velocity distribution in stellar clusters. Monthly Notices of the Royal Astronomical Society, 508 (2). pp. 2302-2306. ISSN 0035-8711

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Many young and intermediate age massive stellar clusters host bimodal distributions in the rotation rates of their stellar populations, with a dominant peak of rapidly rotating stars and a secondary peak of slow rotators. The origin of this bimodal rotational distribution is currently debated and two main theories have been put forward in the literature. The first is that all/most stars are born as rapid rotators and that interacting binaries brake a fraction of the stars, resulting in two populations. The second is that the rotational distribution is a reflection of the early evolution of pre-main sequence stars, in particular, whether they are able to retain or lose their protoplanetary discs during the first few Myr. Here, we test the binary channel by exploiting multi-epoch VLT/MUSE observations of NGC 1850, a 100Myr massive cluster in the LMC, to search for differences in the binary fractions of the slow and fast rotating populations. If binarity is the cause of the rotational bimodality, we would expect that the slowly rotating population should have a much larger binary fraction than the rapid rotators. However, in our data we detect similar fractions of binary stars in the slow and rapidly rotating populations (5.9+/-1.1% and 4.5+/-0.6%, respectively).Hence, we conclude that binarity is not a dominant mechanism in the formation of the observed bimodal rotational distributions.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 23 Sep 2021 10:30
Last Modified: 05 Jan 2022 16:30
DOI or ID number: 10.1093/mnras/stab2643
URI: https://researchonline.ljmu.ac.uk/id/eprint/15540
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