Abstract We present comprehensive photometric observations and analysis of the totally eclipsing binary CN Tri. The photometric solutions suggest it as an extremely low mass ratio contact binary system with q ∼ 0.08. Multiband photometry obtained using the WH50 and XL85 telescopes, along with high-cadence time-series photometric data from the Transiting Exoplanet Survey Satellite (TESS), reveals that CN Tri is fundamentally a W-type contact binary. However, the light curve morphology from TESS observations exhibits characteristics typical of A-type systems. We successfully reconciled this apparent contradiction through modeling a time-evolving starspot near orbital phase 0.5, which provides a comprehensive explanation for the anomaly observation in this system. This case study demonstrates that starspot-induced light curve distortions can lead to misclassification of contact binary types, offering a valuable framework for interpreting similar anomalies in other W UMa systems with discrepant photometric classifications.
Wang et al. (Wed,) studied this question.
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