  The presence of exotic states of matter in neutron stars (NSs) is currently
an open issue in physics. The appearance of muons, kaons, hyperons, and other
exotic particles in the inner regions of the NS, favored by energetic
considerations, is considered to be an effective mechanism to soften the
equation of state (EoS). In the so-called two-families scenario, the softening
of the EoS allows for NSs characterized by very small radii, which become
unstable and convert into a quark stars (QSs). In the process of conversion of
a NS into a QS material can be ablated by neutrinos from the surface of the
star. Not only neutron-rich nuclei, but also more exotic material, such as
hypernuclei or deconfined quarks, could be ejected into the atmosphere. In the
NS atmosphere, atoms like H, He, and C should exist, and attempts to model the
NS thermal emission taking into account their presence, with spectra modified
by the extreme magnetic fields, have been done. However, exotic atoms, like
muonic hydrogen $(p\,\mu^-)$ or the so-called Sigmium $(\Sigma^+\,e^-)$, could
also be present during the conversion process or in its immediate aftermath. At
present, analytical expressions of the wave functions and eigenvalues for these
atoms have been calculated only for H. In this work, we extend the existing
solutions and parametrizations to the exotic atoms $(p\,\mu^-)$ and
$(\Sigma^+\,e^-)$, making some predictions on possible transitions. Their
detection in the spectra of NS would provide experimental evidence for the
existence of hyperons in the interior of these stars.
