2019AJ....157...73K

Photometric and spectral observations of the W UMa binaries NSVS 4161544 and 1SWASP J034501.24+493659.9 with periods of around 8 hr are presented. The simultaneous light-curve and radial-velocity-curve solutions revealed that the two targets have over-contact configurations, and their components undergo partial eclipses. The derived parameters of NSVS 4161544 are: mass ratio q = 3.377, orbital inclination i = 65.0⁰, temperatures T₁ = 6016 K and T₂ = 5726 K, masses M₁ = 0.43 M_☉ and M₂ = 1.47 M_☉, radii R₁ = 0.74 R_☉ and R₂ = 1.28 R_☉, luminosities L₁ = 0.64 L_☉ and L₂ = 1.51 L_☉. The derived parameters of 1SWASP J034501.24+493659.9 are: mass ratio q = 2.378, orbital inclination i = 60.3⁰, temperatures T₁ = 6514 K and T₂ = 6494 K, masses M₁ = 0.275 M_☉ and M₂ = 0.654 M_☉, radii R₁ = 0.693 R_☉ and R₂ = 1.012 R_☉, luminosities L₁ = 0.775 L_☉ and L₂ = 1.632 L_☉. Hence, the masses of the 1SWASP J034501.24+493659.9 components are quite small for the rest global parameters, and their sum of 0.93 M_☉ is slightly below the lower mass limit of 1.0-1.2 M_☉ for the contact binaries. The calculated distance of NSVS 4161544 almost coincides with that determined by GAIA. The calculated distance of 1SWASP J034501.24+493659.9 is considerably smaller than the GAIA value that is most likely due to overestimation of the interstellar extinction to this star from the Galactic disk.