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arXiv · 2610.18998

The convective-transition gap in 47 Tucanae with JWST

M. Scalco·L. R. Bedin·M. Libralato·M. Griggio·E. Vesperini·R. Gerasimov
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Abstract

We report the detection of the convective-transition gap along the lower main sequence (MS) of the Galactic globular cluster (GC) 47 Tucanae using deep James Webb Space Telescope (JWST) observations. We analyse the stellar luminosity function (LF) in the vicinity of the gap location using two independent colour-magnitude diagrams (CMDs). In both cases, the LF is characterised by a narrow gap followed by a discontinuous increase in the stellar number counts, and presents an overall morphology qualitatively consistent with that reported in previous studies. By modelling the observed LFs with an empirical likelihood model, we estimate the statistical significance of the observed feature. Additional JWST passbands exhibit similar signatures, providing further evidence for the presence of a discontinuity.

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M. Scalco, L. R. Bedin, M. Libralato, M. Griggio, E. Vesperini, R. Gerasimov. 2026-10-13. The convective-transition gap in 47 Tucanae with JWST. https://arxiv.org/abs/2610.18998

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