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We report a detailed modelling of soft X-ray emission lines from twostellar-wind fed Galactic high mass X-ray binary (HMXB) systems, Cyg X-3 and 4U1538-522, and estimate physical parameters, e.g., hydrogen density, radiationfield, chemical abundances, wind velocity, etc. The spectral synthesis codeCLOUDY is utilized for this modelling. We model highly ionised X-ray spectrallines such as Fe XXV (6.700 keV), Fe XXVI (6.966 keV), and reproduce theobserved line flux values. We find that for Cyg X--3 and 4U 1538-522, the innerradius of the ionised gas is at a distance of 10$^{12.25}$ cm and 10$^{10.43}$cm respectively from the primary star, which is the main source of ionisation.The densities of the ionised gas for Cyg X--3 and 4U 1538--522 are found to be$\sim$ 10$^{11.35}$ cm$^{-3}$ and 10$^{11.99}$ cm$^{-3}$, respectively. Thecorresponding wind velocities are 2000 km s$^{-1}$ and 1500 km s$^{-1}$. Therespective predicted hydrogen column densities for Cyg X--3 and 4U 1538--522are $10^{23.2}$ cm$^{-2}$ and 10$^{22.25}$ cm$^{-2}$. In addition, we find thata magnetic field affects the strength of the spectral lines through cyclotroncooling. Hence, we perform separate model comparisons including a magneticfield for both the sources. Most of the parameters, except the hydrogen columndensity, have similar values with and without a magnetic field. We estimatethat the most probable strength of the magnetic field for Cyg X--3 and 4U1538--522, where the Fe XXV and Fe XXVI lines originate, is $\sim$ 10$^{2.5}$G.

Spectroscopic modelling of two high-mass X-ray binaries, Cyg X--3 and 4U 1538--522