Top view in scale of XB 1916-053 for a mass ratio q = 0.048. Left and right panel: whole binary system and a zoom of it close to the inner Lagrangian point, respectively. The blue curve indicates the Roche lobes of the two stars. The dashed and red circle represent the NS Roche-lobe radius and CS Roche-lobe radius. The magenta, black, and green diamond points are the position of the center of mass (CM), the companion star, and the inner Lagrangian point L₁. The dotted circle is the radius of the companion star, without thermal inflation. The green circle represents the accretion disk truncated at 0.47a (see text). The two black dashed segments indicate the distances from L₁ at which the matter leaves the binary system for a NS mass of 1.4 M_⊙ at a luminosity of 0.41 × 10³⁷ erg s⁻¹ and 1.46 × 10³⁷ erg s⁻¹ going from the closest to the farthest.