2025ApJ...979...69W

Eclipsing binaries (EBs) play an important astrophysical role in studying stellar properties and evolution. By analyzing photometric data in the the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium-Resolution Survey field, R.A.: 23^h01^m51$\mathop{.}\limits^{{\rm{s}}}$00, decl.: +34$^\circ 36^{\prime} 45^{\prime\prime} $, 48 EBs are detected and two are newly discovered. This specific field has been observed 52 times by the LAMOST Medium-Resolution Survey DR 9, which facilitates a comprehensive analysis of the EBs. For EBs with LAMOST medium-resolution spectra, radial velocity curves were obtained, and their precise orbital parameters were determined by simultaneously analyzing photometric light curves and radial velocity curves. For the other EBs with only photometric light curves, we used the q-search or the temperature ratio method to determine their initial mass ratios and then determined the orbital parameters. It is found that 15 EBs belong to detached systems, one to semi-detached systems, and 32 to contact systems. Based on the O - C analysis for 26 EBs with sufficient eclipsing times, we found a long-term decrease in the orbital period of 11 EBs and a continuous increase of five EBs, which are due to the material transfer between the two components. The O - C curve of 1 EB shows a distinct periodic variation, which is caused by the light travel time effect, and the third body is likely to be a black hole. By applying the spectral subtraction method to 13 EBs with LAMOST medium-resolution spectra, 10 systems exhibit distinct Hα emission lines, in which one system exhibits double-peaked lines near phases 0.25 and 0.75, implying strong chromospheric activity. In the massluminosities and mass-radius distributions, most of the more massive components are less evolved than the less massive ones.