2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/210531The classical Heun equation has the form {Q(z) d^2/dz^2 +P(z) d/dz +V(z)}S(z)=0 where Q(z) is a cubic, P(z) at most quadratic and V(z) linear polynomials resp. In the second half of the 19-th century E.Heine and T.STieltjes initiated the study of the set of all V(z) such that the above equation has a polynomial solution S(z) of a given degree n. The main goal of the present paper is to study the union of the roots of the latter set of V(z)*s when n->oo. We formulate an intriguing conjecture of K.Takemura describing the limiting set and give a substantial amount of additional information.14 pages, 5 figuresMathematical PhysicsClassical Analysis and ODEs34L20 (Primary), 30C15, 33E05 (Secondary)On spectral polynomials of the Heun equationtext