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Researchers analyzed Kepler telescope data from over 1,300 stars and discovered that stars with confirmed exoplanets show distinctly different patterns in their rotational modulation compared to stars without detected planets. Planet-hosting stars exhibit a bimodal distribution in their photometric modulation dispersion, with two distinct peaks corresponding to stable, long-lived magnetic regions and rapidly evolving activity patterns. This bimodal signature appears exclusively in planet-hosting stars, suggesting that planetary systems may influence how stellar magnetic activity organizes itself over time.
Why it matters
This finding suggests a previously unknown connection between planetary systems and stellar magnetic activity, which could improve our understanding of star-planet interactions and stellar dynamos. The results may help refine exoplanet detection methods and provide new insights into how planetary systems affect their host stars' behavior over long timescales.
arXiv:2605.26197v1 Announce Type: new
Abstract: Stellar magnetic activity is governed by the interplay between rotation, convection, and the evolution of surface magnetic structures, yet the role of planetary systems in shaping these processes remains uncertain. Here, we analyze textit{Kepler} photometry of more than 1,300 stars to investigate rotational modulation in stars with and without confirmed exoplanets. Using a time–frequency analysis, we measure the photometric proxy of rotational modulation dispersion, $S_{rm phot}$, tracing the temporal coherence of surface magnetic features. Stars hosting confirmed exoplanets exhibit systematically enhanced $S_{rm phot}$ values compared to stars without detected planets ($Delta S_{rm phot}=0.17 pm 0.01$ rad d$^{-1}$; $p<10^{-25}$). More importantly, the $S_{rm phot}$ distribution of planet hosts is bimodal, with peaks at $0.12$ and $0.44$ rad d$^{-1}$ (Hartigan's Dip Test $p<10^{-6}$; $Delta mathrm{BIC}=188.7$), a feature absent in the control sample. We interpret $S_{rm phot}$ as a proxy for rotational modulation dispersion, reflecting spot evolution rather than true differential rotation. The two regimes correspond to stable magnetic coherence with long-lived active regions and rapidly evolving activity patterns. The presence of these distinct regimes exclusively among planet-hosting stars suggests that planetary systems may influence the temporal organization of stellar magnetic activity and indirectly affect stellar dynamos.
Source: Bimodality in Rotational Modulation of Planet-Hosting Stars