The pre-He white dwarfs in eclipsing binaries – III. WASP 1625−04

1SWASP J162545.15-043027.9 (WASP 1625-04) has been announced as one of EL CVn candidates showing total primary eclipses and ellipsoidal variations. This paper presents the absolute properties binary star, based on our high-resolution spectroscopy conducted from 2015 through 2020. From spectral analysis, radial velocities (RVs) for both components were obtained with effective temperature $T_{\rm eff,1} = 8990 \pm 200$ K rotational rate $v_1\sin$$i=53\pm5$ km s$^{-1}$ more massive primary. The RV measurements analyzed archival WASP photometry. modelling we obtained: $M_1 1.745 0.013$ M$_\odot$, $M_2 0.187 0.002$ $R_1 1.626 0.008$ $R_2 0.290 0.003$ $L_1 15.5 1.4$ L$_\odot$, $L_2 1.84 0.16$ L$_\odot$. In Hertzsprung-Russell diagram, 1625-04 A lies zero-age main sequence its companion accords well helium-core white dwarf models 0.19 M$_\odot$ in constant luminosity phase. Our improved results demonstrate that is a typical CVn-type low mass ratio $M_2$ combination thin-disk population product stable, non-conservative transfer precursor binary.