Axion helioscopes search for solar axions by exploiting their conversion into X-ray photons
within strong magnetic fields via the Primakoff effect. The Sun provides an intense and well characterized
axion source, as axions can be produced in its core through photon–plasma interactions.
By aligning powerful magnets with the solar direction and employing low-background X-ray detectors, helioscopes aim to detect these converted photons as a direct experimental signature
of axion–photon coupling.
In addition to this laboratory approach, axion from thermal photons in the solar core may reconvert
into X-rays within the magnetic fields of the solar atmosphere, producing a faint, spatially
extended, and spectrally distinct X-ray signal that could be detectable by dedicated satellite missions.
Axion production mechanisms are also enabled in other stellar environments. Nearby red supergiants
such as Betelgeuse represent particularly promising targets: their hot cores can generate
substantial ALP fluxes that reconvert into X-rays within Galactic magnetic fields, while the absence
of stable coronae reduces conventional X-ray backgrounds. Dedicated NuSTAR observations
of Betelgeuse have already placed competitive limits on the couplings gaγ , gae, and gaN,
improving upon CAST constraints and approaching the sensitivities expected for next-generation
experiments such as ALPS-II and BabyIAXO. Complementary searches in nearby systems, including
the Alpha Centauri binary, M82 and M87 further explore scenarios involving gravitationally
trapped ALPs decaying into monochromatic X-rays, providing robust, multi-channel constraints on axion and ALP interactions across diverse astrophysical sources.