000168151 001__ 168151 000168151 005__ 20260127160850.0 000168151 0247_ $$2doi$$a10.1103/xv5c-j2rv 000168151 0248_ $$2sideral$$a147691 000168151 037__ $$aART-2025-147691 000168151 041__ $$aeng 000168151 100__ $$aCandón, Francisco R. 000168151 245__ $$aProbing the axion-nucleon coupling with supergiant stars 000168151 260__ $$c2025 000168151 5060_ $$aAccess copy available to the general public$$fUnrestricted 000168151 5203_ $$aA 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. 000168151 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es 000168151 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000168151 700__ $$aCasaseca, Pablo 000168151 700__ $$0(orcid)0000-0001-9823-6262$$aGiannotti, Maurizio$$uUniversidad de Zaragoza 000168151 700__ $$0(orcid)0000-0002-6470-5371$$aKaltschmidt, Mathieu$$uUniversidad de Zaragoza 000168151 700__ $$0(orcid)0000-0002-3253-7027$$aRuz, Jaime 000168151 700__ $$0(orcid)0000-0002-5850-5517$$aVogel, Julia K. 000168151 7102_ $$12004$$2038$$aUniversidad de Zaragoza$$bDpto. Física Teórica$$cÁrea Astronomía y Astrofísica 000168151 7102_ $$12004$$2405$$aUniversidad de Zaragoza$$bDpto. Física Teórica$$cÁrea Física Teórica 000168151 773__ $$g112, 12 (2025)$$pPhys. rev. D$$tPhysical Review D$$x2470-0010 000168151 8564_ $$s1201857$$uhttps://zaguan.unizar.es/record/168151/files/texto_completo.pdf$$yVersión publicada 000168151 8564_ $$s2913957$$uhttps://zaguan.unizar.es/record/168151/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000168151 909CO $$ooai:zaguan.unizar.es:168151$$particulos$$pdriver 000168151 951__ $$a2026-01-27-15:01:23 000168151 980__ $$aARTICLE