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Kinematic differences between multiple populations in Galactic globular clusters

Martens, S, Kamann, S, Dreizler, S, Göttgens, F, Husser, T-O, Latour, M, Balakina, E, Krajnović, D, Pechetti, R and Weilbacher, PM (2023) Kinematic differences between multiple populations in Galactic globular clusters. Astronomy and Astrophysics, 671. ISSN 0004-6361

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Open Access URL: https://doi.org/10.1051/0004-6361/202244787 (published)


Aims. The formation process of multiple populations in globular clusters is still up for debate. These populations are characterized by different light-element abundances. Kinematic differences between the populations are particularly interesting in this respect, because they allow us to distinguish between single-epoch formation scenarios and multi-epoch formation scenarios. We derive rotation and dispersion profiles for 25 globular clusters and aim to find kinematic differences between multiple populations in 21 of them to constrain the formation process.
Methods. We split red-giant branch (RGB) stars in each cluster into three populations (P1, P2, P3) for the type-II clusters and two populations (P1 and P2) otherwise using Hubble photometry. We derive the global rotation and dispersion profiles for each cluster by using all stars with radial velocity measurements obtained from MUSE spectroscopy. We also derive these profiles for the individual populations of each cluster. Based on the rotation and dispersion profiles, we calculate the rotation strength in terms of ordered-overrandom motion (v/σ)HL evaluated at the half-light radius of the cluster. We then consistently analyse all clusters for differences in the rotation strength of their populations.
Results. We detect rotation in all but four clusters. For NGC 104, NGC 1851, NGC 2808, NGC 5286, NGC 5904, NGC 6093, NGC 6388, NGC 6541, NGC 7078 and NGC 7089 we also detect rotation for P1 and/or P2 stars. For NGC 2808, NGC 6093 and NGC 7078 we find differences in (v/σ)HL between P1 and P2 that are larger than 1σ. Whereas we find that P2 rotates faster than P1 for NGC 6093 and NGC 7078, the opposite is true for NGC 2808. However, even for these three clusters the differences are still of low significance. We find that the strength of rotation of a cluster generally scales with its median relaxation time. For P1 and P2 the corresponding relation is very weak at best. We observe no correlation between the difference in rotation strength between P1 and P2 and cluster relaxation time. The stellar radial velocities derived from MUSE data that this analysis is based on are made publicly available.

Item Type: Article
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: EDP Sciences
Related URLs:
SWORD Depositor: A Symplectic
Date Deposited: 27 Jan 2023 10:23
Last Modified: 14 Mar 2023 09:30
DOI or ID number: 10.1051/0004-6361/202244787
URI: https://researchonline.ljmu.ac.uk/id/eprint/18744
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