168151 20260127160850.0 doi 10.1103/xv5c-j2rv sideral 147691 ART-2025-147691 eng Candón, Francisco R. Probing the axion-nucleon coupling with supergiant stars 2025 A finite axion-nucleon coupling enables the production of axions in stellar environments via the thermal excitation and subsequent deexcitation of the Fe-57 isotope. Given its low-lying excited state at 14.4 keV,Fe- 57 can be efficiently excited in the hot cores of supergiant stars, possibly leading to axion emission. The conversion of these axions into photons in the Galactic magnetic field results in a characteristic 14.4 keV line, potentially detectable by hard x-ray telescopes such as NASA's Nuclear Spectroscopic Telescope Array (NuSTAR). In this work, we present the first constraints on axion-nucleon couplings derived from NuSTAR observations of Betelgeuse and discuss the potential insights that could be gained from detecting this line in other nearby supergiants. Our results establish significantly more stringent bounds than those obtained from solar observations, setting a limit of |g(a gamma)g(aN)(eff)| < (1.2-2.7) x 10(-20) GeV-1 for m(a) less than or similar to 10(-10) eV. Access copy available to the general public Unrestricted info:eu-repo/semantics/openAccess by https://creativecommons.org/licenses/by/4.0/deed.es info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Casaseca, Pablo Giannotti, Maurizio Universidad de Zaragoza (orcid)0000-0001-9823-6262 Kaltschmidt, Mathieu Universidad de Zaragoza (orcid)0000-0002-6470-5371 Ruz, Jaime (orcid)0000-0002-3253-7027 Vogel, Julia K. (orcid)0000-0002-5850-5517 2004 038 Universidad de Zaragoza Dpto. Física Teórica Área Astronomía y Astrofísica 2004 405 Universidad de Zaragoza Dpto. Física Teórica Área Física Teórica 112, 12 (2025) Phys. rev. D Physical Review D 2470-0010 1201857 http://zaguan.unizar.es/record/168151/files/texto_completo.pdf Versión publicada 2913957 http://zaguan.unizar.es/record/168151/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:168151 articulos driver 2026-01-27-15:01:23 ARTICLE