2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/211413The fast spinning B-star Regulus has recently been found to be orbited by a fainter companion in a close circular path with orbital period P_b = 40.11(2) d. Being its equatorial radius R_e 32% larger than the polar one R_p, Regulus possesses a remarkable quadrupole mass moment Q. We investigate the effects of Q on the orbital period P_b of its companion in order to see if they are measurable, given the present-day level of accuracy in measuring P_b. Conversely, we will look for deviations from the third Kepler law, attributed to the quadrupole mass moment Q of Regulus, to constrain the ratio γ=m/M of the system's masses.LaTex, 6 pages, 5 figures, 1 table. Accepted by Astrophysics and Space ScienceGeneral Relativity and Quantum CosmologyAstrophysicsSpace Physicstext