Searching for Stellar Activity Cycles using Flares II: The TESS CVZ

arXiv:2607.12883 · astro-ph.SR · Submitted 2026-07-14 · Read on arXiv

Tobin M. Wainer, Holland M. Stuart, Guadalupe Tovar Mendoza, Andrew R. Casey, Tom Wagg, James R. A. Davenport

astro-ph.SR

Submitted: 2026-07-14

Comments: 21 pages, 9 figures with more available online, 3 tables. Submitted to AAS journals

Code: https://github.com/tobinwainer/Searching_For_Activity_Cycles_Using_Flares_Public_Interface

License: http://creativecommons.org/licenses/by/4.0/

The gist: Magnetic activity cycles provide a fundamental constraint on stellar dynamos, but remain difficult to identify beyond the Sun.

Terminology

Abstract

Magnetic activity cycles provide a fundamental constraint on stellar dynamos, but remain difficult to identify beyond the Sun. However, recent studies have shown that flares offer a unique tracer of activity cycle behavior. In this study, we use seven years of short-cadence observations from the Transiting Exoplanet Survey Satellite (TESS) for over 14,000 stars in the Continuous Viewing Zone to search for long-term changes in flare activity. For each star, we perform injection and recovery tests and provide well-characterized completeness limits for flare detection thresholds, and flare finding results. From this search, we identify 17 stars with evidence of long-term variability in flare rate, synonymous with activity cycle behavior. These candidates span a range of effective temperatures, rotation periods, and flare-variability morphologies. One G-type star, TIC 167344043, stands out as the clearest solar-like case, despite rapid rotation and superflare activity. Our results identify candidate activity cycles in stars that are more rapidly rotating and flare-active than the typical stellar-activity-cycle targets in the literature. These systems probe a new regime where stellar dynamos are still evolving, providing critical constraints on when cycle-like magnetic variability first emerges.

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