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arXiv · 2512.19218

Multi-wavelength study of the pre-eruption dip in the recurrent nova T Coronae Borealis preceding imminent nova eruption

Songpeng Pei·Xiaowan Zhang·Renzhi Su·Yongzhi Cai·Ziwei Ou·Qiang Li·Xiaoqin Ren·Taozhi Yang·Mingyue Li
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Abstract

We present a multi-wavelength study of the symbiotic recurrent nova (RN) T Coronae Borealis (T CrB) using Swift Burst Alert Telescope (BAT) / X-Ray Telescope (XRT) / UltraViolet Optical Telescope (UVOT) and American Association of Variable Stars Observers (AAVSO) observations from 2005 to 2025. Our analysis spans quiescent, high, and pre-eruption dip states. We find that brightening amplitudes increase toward shorter wavelengths in both optical and UV bands, while the UV and X-ray fluxes are generally anti-correlated throughout all phases. During the 2023-2024 pre-eruption dip, soft and hard X-rays increased as optical and ultraviolet (UV) brightness declined, consistent with a transition from an optically thick to thin boundary layer driven by a reduction in the accretion rate. We also report, for the first time, a second, lower-amplitude dip occurring between September 2024 and February 2025 following the primary 2023-2024 pre-eruption dip. The observed variability supports an accretion-variation scenario as a unifying explanation for both the high and dip states, and may signal an imminent nova eruption.

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Songpeng Pei, Xiaowan Zhang, Renzhi Su, Yongzhi Cai, Ziwei Ou, Qiang Li, Xiaoqin Ren, Taozhi Yang, Mingyue Li. 2025-12-22. Multi-wavelength study of the pre-eruption dip in the recurrent nova T Coronae Borealis preceding imminent nova eruption. https://arxiv.org/abs/2512.19218

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