Abstract
The axion is a new particle expected in the Standard model to solve the QCD puzzle. It is a strong candidate for dark matter. Moreover, axion production from astrophysical bodies is a topic in continuous development, because of theoretical progress in the estimate of stellar emission rates and, especially, because of improved stellar observations. We carry out a comprehensive analysis of the most informative astrophysics data, revisiting the bounds on axion couplings to photons, nucleons and electrons. We confront the performance of various theoretical constructions in complying with the observational limits on axion couplings. Finally, we scrutinize the discovery potential for such models at upcoming helioscopes, namely IAXO and its scaled versions. We also discuss the cosmological and phenomenological implications.