Tracing stellar rotation in young massive LMC clusters

Kamann, S ORCID: 0000-0001-6604-0505, Bastian, N, Niederhofer, F, Bellini, A, Cabrera-Ziri, I, Dreizler, S, Göttgens, F, Kozhurina-Platais, V, Libralato, M, Martens, S and Saracino, S (2025) Tracing stellar rotation in young massive LMC clusters. Monthly Notices of the Royal Astronomical Society, 542 (4). pp. 2768-2784. ISSN 0035-8711

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Abstract

We present a detailed analysis of stellar rotation along the main sequences of NGC 1866 and NGC 1856, two young (200-300 Myr) massive clusters in the Large Magellanic Cloud, using MUSE integral field spectroscopy. Differences in stellar rotation have been proposed as an explanation for the extended main sequence turn-offs and split main sequences in these clusters. In agreement with this idea, we find strong links between the photometric colours of the cluster stars and their projected rotation velocities,. While stars blueward of the split main sequences are characterized by a range of relatively low spins, those with redder colours are fast rotators. Following a statistical correction for inclination, we measure mean equatorial velocities for the red main-sequence stars in both clusters of km s, corresponding to 70-80 per cent of the critical values predicted for such stars by current stellar models. We discuss these findings in the context of the different scenarios proposed to explain the stellar rotation distributions of young massive clusters. We further investigate whether the high rotation rates provide a natural explanation for the high fractions of Be stars we observe in both clusters, peaking at 50 per cent at the turn-off. We argue that if of the critical rotation rate is high enough to trigger the formation of a decretion disc, most upper main sequence stars in the clusters are expected to become Be stars before leaving the main sequence.

Item Type:	Article
Uncontrolled Keywords:	techniques: imaging spectroscopy; stars: rotation; galaxies: star clusters: individual: NGC 1856, NGC 1866; 5109 Space Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	11 August 2025
Date of first compliant Open Access:	10 September 2026
Date Deposited:	10 Sep 2026 13:17
Last Modified:	10 Sep 2026 13:17
DOI or ID number:	10.1093/mnras/staf1371
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29378

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