2021RAA....21..180L

The first B-, V-, Rc- and Ic-band light curves of CSS J022914.4+044340 are presented and analyzed. It is found that CSS J022914.4+044340 is a low mass ratio (0.198 ± 0.005) deep (63.7 ± 7.9%) contact binary, indicating that it is already at the end evolutionary stage of tidally-locked evolution via magnetized wind. Because of the totally eclipsing character, the photometric solutions are reliable. The temperature and metallicity are determined from the spectroscopic data as T = 5855 ± 15 K and [Fe/H] = -0.842 ± 0.031, respectively. Based on the parallax of Gaia EDR3, the physical parameters of CSS J022914.4+044340 are estimated as {M}_{1}={1.44}{-0.22}^{+0.25}{M}_☉ , {M}_{2}={0.29}{-0.05}^{+0.05}{M}_☉ , {R}_{1}={1.26}{-0.06}^{+0.08}{R}_☉ , {R}_{2}={0.65}{-0.04}^{+0.03}{R}_☉ , L_{1}={1.718}{-0.191}^{+0.186}L_☉ and L_{2}={0.416}{-0.050}^{+0.039}L_☉ . Combining the fraction of light from the third body via the photometric solution (54%), the luminosity of the third body is estimated as 2.705 L☉. The third body may be inferred to be a subgiant. Thus, why the primary component of CSS J022914.4+044340 has higher mass compared to similar systems is explained, as well as why its metallicity is so poor.