Positions of the LMXBs from Table 1 on the orbital period – X-ray luminosity diagram. Filled circles denote the positions of peculiar systems: grey circles show the positions of binaries with white dwarf or hydrogen-deficit accretors, and the dashed circle shows the position of 4U1822-37 in which we see only a fraction of the total X-ray luminosity due to its nearly edge-on orientation (a so-called accretion disk corona source). The region, occupied by binary systems with a giant donor is shown by the shaded square. The dashed line shows the slope L_x ∝ P^2.5 derived by Iben & Tutukov (1984) for the mass transfer rate in binaries in which angular momentum loss is driven by a magnetic stellar wind from a main-sequence donor. The dotted line shows the boundary of persistency according to the thermal-viscous disk instability for binaries with low-mass main-sequence donors L_x/10³⁷ erg/s from Eq. (32) of Dubus et al. (1999), where we adopted M₁ = 1.4   M_⊙, M₂ = 0.4   M_⊙, and L_x = 0.1   Ṁc².