A star's death by a thousand cuts: the runaway periodic eruptions of AT2023uqm.

Authors

Yibo Wang, Tinggui Wang, Shifeng Huang, Jiazheng Zhu, Ning Jiang, Wenbin Lu, Rongfeng Shen, Shiyan Zhong, Dong Lai, Yi Yang, Xinwen Shu, Tianyu Xia, Di Luo, Jianwei Lyu, Alexei V Filippenko, Thomas G Brink, Weikang Zheng, Minxuan Cai, Zelin Xu, Mingxin Wu, Xiaer Zhang, Weiyu Wu, Lulu Fan, Ji-An Jiang, Xu Kong, Bin Li, Feng Li, Ming Liang, Wentao Luo, Jinlong Tang, Zhen Wan, Hairen Wang, Jian Wang, Yongquan Xue, Dazhi Yao, Hongfei Zhang, Wen Zhao, Xianzhong Zheng, Qingfeng Zhu, Yingxi Zuo

Published in

Science bulletin. Aug 19, 2026. Epub Aug 19, 2026.

Abstract

Stars on bound orbits around a supermassive black hole may undergo repeating partial tidal disruption events (rpTDEs), producing periodic flares. While several candidates have been suggested, definitive confirmation of these events remains elusive. We report the discovery of AT2023uqm, a nuclear transient that has exhibited at least five periodic optical flares, making it only the second confirmed case of periodicity after ASASSN-14ko. Uniquely, the flares from AT2023uqm show a nearly exponential increase in energy-a "runaway" phenomenon signaling the star's progressive destruction. This behavior is consistent with rpTDEs of low-mass main-sequence stars or evolved giant stars. Multiwavelength observations and spectroscopic analysis of the two most recent flares reinforce its interpretation as an rpTDE. Intriguingly, each flare displays a similar double-peaked structure, potentially originating from a double-peaked mass fallback rate or two discrete collisions per orbit. The extreme ratio of peak separation to orbital period draws attention to the possibility of a giant star being disrupted, which could be distinguished from a low-mass main-sequence star by its future mass-loss evolution. Our analysis demonstrates the power of rpTDEs to probe the properties of disrupted stars and the physical processes of tidal disruption, though it is currently limited by our knowledge of these events. AT2023uqm emerges as the most compelling rpTDE thus far, serving as a crucial framework for modeling and understanding these phenomena.

PMID:
42686503
Bibliographic data and abstract were imported from PubMed on 03 Sep 2026.

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