Euclid: The convective-transition gap of 47 Tuc
Abstract
We report the first detection of the `convective-transition gap' (also known as `M-dwarf gap') in the globular cluster 47 Tuc (NGC 104) thanks to Euclid data. This feature, linked to a change in the physical properties of late-type dwarfs, has remained elusive, with only two detections so far. Leveraging the large number of stars, high resolution, and photometric precision enabled by Euclid, we detect a statistically significant, sharp discontinuity in the main-sequence luminosity function of 47 Tuc at , which we identify as the convective-transition gap. We compare the observed properties of the gap in 47 Tuc with theoretical models, showing how the gap can be a powerful diagnostic to probe the internal chemical structure of globular clusters, and their multiple stellar populations. Following its initial discovery in the metal-poor cluster NGC 6397, the identification of a convective gap in the metal-rich 47 Tuc suggests that this feature might be more general than previously thought. These results demonstrate that Euclid can be transformative well beyond cosmology, with impact across multiple areas of astrophysics, including resolved stellar populations.
Cite
@article{arxiv.2606.28504,
title = {Euclid: The convective-transition gap of 47 Tuc},
author = {M. Libralato and M. Griggio and R. Gerasimov and L. R. Bedin and I. McDonald and B. Altieri and J. Anderson and F. Annibali and E. Balbinot and G. Battaglia and A. Bellini and P. Casenove and J. -C. Cuillandre and E. Dalessandro and A. M. N. Ferguson and H. R. A. Jones and K. Kuijken and F. Z. Majidi and D. Massari and A. Mohandasan and F. Niederhofer and G. Polenta and J. D. Sakowska and F. Soldano and C. Zerbinati and S. Andreon and N. Auricchio and H. Aussel and C. Baccigalupi and M. Baldi and A. Balestra and P. Battaglia and A. Biviano and E. Branchini and M. Brescia and S. Camera and V. Capobianco and C. Carbone and J. Carretero and M. Castellano and G. Castignani and S. Cavuoti and K. C. Chambers and A. Cimatti and C. Colodro-Conde and G. Congedo and C. J. Conselice and L. Conversi and Y. Copin and F. Courbin and H. M. Courtois and M. Cropper and H. Degaudenzi and G. De Lucia and H. Dole and F. Dubath and X. Dupac and M. Farina and R. Farinelli and F. Faustini and S. Ferriol and M. Frailis and E. Franceschi and S. Galeotta and K. George and B. Gillis and C. Giocoli and J. Gracia-Carpio and A. Grazian and F. Grupp and S. V. H. Haugan and H. Hoekstra and W. Holmes and I. M. Hook and F. Hormuth and A. Hornstrup and K. Jahnke and M. Jhabvala and S. Kermiche and A. Kiessling and B. Kubik and M. Kümmel and M. Kunz and H. Kurki-Suonio and A. M. C. Le Brun and S. Ligori and P. B. Lilje and V. Lindholm and I. Lloro and O. Mansutti and O. Marggraf and M. Martinelli and N. Martinet and F. Marulli and R. J. Massey and E. Medinaceli and S. Mei and M. Meneghetti and E. Merlin and G. Meylan and A. Mora and L. Moscardini and R. Nakajima and R. C. Nichol and S. -M. Niemi and C. Padilla and S. Paltani and F. Pasian and W. J. Percival and V. Pettorino and M. Poncet and L. A. Popa and F. Raison and A. Renzi and J. Rhodes and G. Riccio and F. Rizzo and E. Romelli and M. Roncarelli and R. Saglia and Z. Sakr and D. Sapone and M. Schirmer and P. Schneider and T. Schrabback and A. Secroun and E. Sihvola and P. Simon and C. Sirignano and G. Sirri and L. Stanco and P. Tallada-Crespí and A. N. Taylor and I. Tereno and S. Toft and R. Toledo-Moreo and F. Torradeflot and I. Tutusaus and J. Valiviita and T. Vassallo and Y. Wang and J. Weller and D. Scott},
journal= {arXiv preprint arXiv:2606.28504},
year = {2026}
}
Comments
12 pages, 10 figures. Accepted for publication in A&A on 25 June 2026, first submission to A&A on 2 June 2026. Official Euclid data available at the CDS upon publication