Comprehensive photometric investigation was carried out to the early K-type contact binary - IL Cnc. A few light curves from both ground-based telescopes and the Kepler space telescope were obtained (or downloaded) and then analyzed in detail. They are mostly found to be asymmetric and there are even continuously changing O'Connell effect in the light curves from Kepler K2 data, suggesting the system to be highly active. Using the Wilson-Devinney code (version 2013), photometric solutions were derived and then compared. It is found that the calculation of the mass ratio is easily affected by the spot settings. Combining the radial velocities determined from LAMOST median resolution spectral data, the mass ratio of the binary components is found to be $M_2/M_1 = 1.76\pm 0.05$. The components are in shallow contact ($f\sim 9\%$) and have a temperature difference about $T_2 - T_1 = -280\pm 20$ K. The system is demonstrated to be W-subtype, which may be a common feature of K-type contact binaries. The masses of the binary components were estimated to be $M_1\sim 0.51$ M$_{sun}$ and $M_2\sim 0.90$ M$_{sun}$. The values are in good agreement with that deduced from the parallax data of Gaia. The results suggest that the primary component lacks luminosity compared with the zero main sequence. The H$\alpha$ spectral line of the primary component is found to be peculiar. Combining newly determined minimum light times with those collected from literature, the orbital period of IL Cnc is studied. It is found that the (O$-$C)s of the primary minima show sinusoidal variation while the secondary do not. The oscillation is more likely to be caused by the starspot activities. Yet this assumption needs more data to support.

中文翻译：

---

活性早期 K 型接触系统的综合光度学研究——IL Cancri

对早期的 K 型接触二元 - IL Cnc 进行了全面的光度研究。获得（或下载）地面望远镜和开普勒太空望远镜的一些光变曲线，然后进行详细分析。它们大多被发现是不对称的，开普勒 K2 数据的光变曲线中甚至存在不断变化的奥康奈尔效应，表明该系统高度活跃。使用 Wilson-Devinney 代码（2013 版），推导出光度学解决方案，然后进行比较。发现质量比的计算容易受到光斑设置的影响。结合从 LAMOST 中值分辨率光谱数据确定的径向速度，发现二元组分的质量比为 $M_2/M_1 = 1.76\pm 0.05$。组件为浅接触（$f\sim 9\%$），温差约为 $T_2 - T_1 = -280\pm 20$ K。系统被证明是 W 亚型，这可能是一个常见的K型接触二进制的特征。二元组件的质量估计为 $M_1\sim 0.51$ M$_{sun}$ 和 $M_2\sim 0.90$ M$_{sun}$。这些值与从盖亚的视差数据推导出的值非常吻合。结果表明，与零主序相比，主成分缺乏光度。发现主成分的 H$\alpha$ 谱线是奇特的。将新确定的最小光时间与从文献中收集的时间相结合，研究了 IL Cnc 的轨道周期。发现初级最小值的 (O$-$C) 显示正弦变化，而次级则没有。振荡更有可能是由星点活动引起的。然而，这个假设需要更多的数据来支持。