We derive rigorously the magneto-Boussinesq system for a gaseous star as done formally by Spiegel and Weiss ("Magnetic Buoyancy and the Boussinesq Approximation'', 1982). In contrast to their result, we take also into account the boundary conditions for the temperature, leading to an additional non-local temperature term in the limit. We shall then give physical meaning to our "mathematical'' system compared to the "physical'' Spiegel-Weiss system. This is joint work with Piotr Gwiazda and Aneta Wróblewska-Kamińska (both IMPAN).