A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

Jie Lin, Chengyuan Wu, Heran Xiong, Xiaofeng Wang, Péter Németh, Zhanwen Han, Jiangdan Li, N. Elias–Rosa, I. Salmaso, A. V. Filippenko, Thomas G. Brink, Yi Yang, Xuefei Chen, Shengyu Yan, Jujia Zhang, Sufen Guo, Yongzhi Cai, Jun Mo, Gaobo Xi, Jialian Liu, Jincheng Guo, Qiqi Xia, Danfeng Xiang, Gaici Li, Zhenwei Li, WeiKang Zheng, Jicheng Zhang, Qichun Liu, Fangzhou Guo, Liyang Chen, Wenxiong Li