Dynamically driven collapse of a thermally stable accretion disk in a nova-like system
Abstract
While standard disk instability theory predicts thermal-steady, outburst-free disks in nova-like variables due to their high mass transfer rates, mass transfer variations are prevailingly invoked to explain the occasional flaring/fading phenomena observed in these systems. Here we report the observational evidence for a dynamical collapse of a thermally stable accretion disk, captured serendipitously by TESS during a fading episode of the VY Scl-type nova-like system MASTER OT J072703.91-631952.8, and traced by the emergence of an unusual negative superhump that evolves toward its orbital frequency. Simultaneously, the system underwent an anomalous eruptive event featuring a remarkably symmetric 45-day light-curve profile, indicative of a mild energy-release mechanism fundamentally distinct from documented eruptive events in cataclysmic variables. Notably, the concurrence of the eruption and the disk collapse is difficult to reconcile with the paradigm of mass transfer variations: the eruption implies enhanced mass transfer, whereas the disk collapse indicates a decline. The morphological disk evolution over ∼ 700 days, characterized by both negative and positive superhumps, indicates a transition from a circular disk to an eccentric disk, followed by a tilted state and ultimately a minimal disk configuration. This evolutionary sequence provides evidence for a previously unrecognized dynamics-driven cycle operating in the thermally stable accretion disk of a VY Scl-type nova-like star.
Versions
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BibTeX
@misc{li2026dynamically,
title = {{Dynamically driven collapse of a thermally stable accretion disk in a nova-like system}},
author = {Wentao Li and Jie Lin and Tinggui Wang and Yongkang Sun and Chengyuan Wu and Heran Xiong and Krystian Iłkiewicz and Luca Casagrande and Michael Bessell and Ning Jiang and Chengyi Wang},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.27878},
eprint = {2608.27878},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.27878},
}
RIS
TY - UNPB
TI - Dynamically driven collapse of a thermally stable accretion disk in a nova-like system
AU - Wentao Li
AU - Jie Lin
AU - Tinggui Wang
AU - Yongkang Sun
AU - Chengyuan Wu
AU - Heran Xiong
AU - Krystian Iłkiewicz
AU - Luca Casagrande
AU - Michael Bessell
AU - Ning Jiang
AU - Chengyi Wang
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2608.27878
UR - https://arxiv.org/abs/2608.27878
AB - While standard disk instability theory predicts thermal-steady, outburst-free disks in nova-like variables due to their high mass transfer rates, mass transfer variations are prevailingly invoked to explain the occasional flaring/fading phenomena observed in these systems. Here we report the observational evidence for a dynamical collapse of a thermally stable accretion disk, captured serendipitously by TESS during a fading episode of the VY Scl-type nova-like system MASTER OT J072703.91-631952.8, and traced by the emergence of an unusual negative superhump that evolves toward its orbital frequency. Simultaneously, the system underwent an anomalous eruptive event featuring a remarkably symmetric 45-day light-curve profile, indicative of a mild energy-release mechanism fundamentally distinct from documented eruptive events in cataclysmic variables. Notably, the concurrence of the eruption and the disk collapse is difficult to reconcile with the paradigm of mass transfer variations: the eruption implies enhanced mass transfer, whereas the disk collapse indicates a decline. The morphological disk evolution over ∼ 700 days, characterized by both negative and positive superhumps, indicates a transition from a circular disk to an eccentric disk, followed by a tilted state and ultimately a minimal disk configuration. This evolutionary sequence provides evidence for a previously unrecognized dynamics-driven cycle operating in the thermally stable accretion disk of a VY Scl-type nova-like star.
ER -