Abstract
We present spectroscopy of individual stars in 26 Magellanic Cloud (MC) star clusters with the aim of estimating dynamical masses and V-band mass-To-light (M/LV) ratios over a wide range in age and metallicity. We obtained 3137 high-resolution stellar spectra with M2FS on the Magellan/Clay Telescope. Combined with 239 published spectroscopic results of comparable quality, we produced a final sample of 2787 stars with good quality spectra for kinematic analysis in the target clusters. Line-of-sight velocities measured from these spectra and stellar positions within each cluster were used in a customized expectation-maximization (EM) technique to estimate cluster membership probabilities. Using appropriate cluster structural parameters and corresponding single-mass dynamical models, this technique ultimately provides self-consistent total mass and M/LV estimates for each cluster. Mean metallicities for the clusters were also obtained and tied to a scale based on calcium IR triplet metallicities. We present trends of the cluster M/LV values with cluster age, mass, and metallicity, and find that our results run about 40 per cent on average lower than the predictions of a set of simple stellar population (SSP) models. Modified SSP models that account for internal and external dynamical effects greatly improve agreement with our results, as can models that adopt a strongly bottom-light IMF. To the extent that dynamical evolution must occur, a modified IMF is not required to match data and models. In contrast, a bottom-heavy IMF is ruled out for our cluster sample as this would lead to higher predicted M/LV values, significantly increasing the discrepancy with our observations.
Original language | English (US) |
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Pages (from-to) | 4160-4191 |
Number of pages | 32 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 504 |
Issue number | 3 |
DOIs | |
State | Published - Jul 1 2021 |
Keywords
- Magellanic Clouds
- galaxies: star clusters: general
- stars: Abundances
- stars: kinematics and dynamics
- techniques: radial velocities
- techniques: spectroscopic
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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Results for 26 star clusters in the Mag. Clouds
Song, Y.-Y. (Creator), Mateo, M. (Creator), Bailey, J. I. (Creator), Walker, M. G. (Creator), Roederer, I. U. (Creator), Olszewski, E. W. (Creator), Reiter, M. (Creator) & Kremin, A. (Creator), Centre de Donnees Strasbourg (CDS), 2024
DOI: 10.26093/cds/vizier.75044160, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/504/4160
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