Araya, IChristen, ACuré, MCidale, L SVenero, R O JArcos, CGormaz-Matamala, A CHaucke, MEscárate, PClavería, H2022-11-302022-11-302021I Araya, A Christen, M Curé, L S Cidale, R O J Venero, C Arcos, A C Gormaz-Matamala, M Haucke, P Escárate, H Clavería, Analytical solutions for radiation-driven winds in massive stars – II. The δ-slow regime, Monthly Notices of the Royal Astronomical Society, Volume 504, Issue 2, June 2021, Pages 2550–2556, https://doi.org/10.1093/mnras/stab995http://repositoriobibliotecas.uv.cl/handle/uvscl/7221Accurate mass-loss rates and terminal velocities from massive stars winds are essential to obtain synthetic spectra from radiative transfer calculations and to determine the evolutionary path of massive stars. From a theoretical point of view, analytical expressions for the wind parameters and velocity profile would have many advantages over numerical calculations that solve the complex non-linear set of hydrodynamic equations. In a previous work, we obtained an analytical description for the fast wind regime. Now, we propose an approximate expression for the line-force in terms of new parameters and obtain a velocity profile closed-form solution (in terms of the Lambert W function) for the δ-slow regime. Using this analytical velocity profile, we were able to obtain the mass-loss rates based on the m-CAK theory. Moreover, we established a relation between this new set of line-force parameters with the known stellar and m-CAK line-force parameters. To this purpose, we calculated a grid of numerical hydrodynamical models and performed a multivariate multiple regression. The numerical and our descriptions lead to good agreement between their values.© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical SocietyHYDRODYNAMICSMETHODS: ANALYTICALSTARS: EARLY-TYPESTARS: MASS-LOSSSTARS: WINDSOUTFLOWSArticulohttps://doi.org/10.1093/mnras/stab995