  Massive axions of the Kaluza-Klein type, created inside the solar core, can
be gravitationally trapped by the Sun itself in orbits inside/outside the Sun,
where they accumulate over cosmic times. Their radiative decay can give rise to
various solar phenomena, like the celebrated solar coronal heating, which lacks
a conventional explanation since its first observation in 1939. Such and other
recent observations favour the existence of a halo of exotic particles near the
Sun. X-ray telescopes can provide novel and important information. The
underlying solar axion scenario is presented in details in ref.'s [4,15]
