2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/3522It is usually accepted to consider an apsidal motion in binary stars as a direct confirmation that a substance inside stars is not uniformly distributed. It is shown in this paper that the apsidal motion in binary systems observation data is in a good agreement with an existence of uniform plasma cores inside stars if they consist of hydrogen-deuterium-helium mixture.9 pages, 2 figuresAstrophysicstext