Magnetic Activity Cycles and Rotation in Planet-hosting and Non-hosting Solar-type Stars

TL;DR

This study analyzes stellar magnetic activity and rotation in 767 Gaia RV standard stars, identifying new rotation and magnetic cycle periods, and exploring their relation to planetary presence and stellar dynamo theory.

Contribution

It reports new rotation and magnetic cycle periods, assesses the impact of stellar activity on RV signals, and investigates the rotation-cycle relationship in stars with and without planets.

Findings

Detected rotation periods in 125 stars, including 30 new estimates.

Identified magnetic activity cycles in 127 stars, 95 of which are new.

Stars with planets show a steeper rotation-cycle period trend than non-hosts.

Abstract

We analyze periodicities in radial velocity (RV) measurements and magnetic activity indicators (S-index and BIS) for 767 Gaia RV standard stars to distinguish between stellar activity and planetary signals. Significant RV periods were detected in only 359 of these stars. Rotation and magnetic cycle periods are identified through iterative periodogram analysis. Among stars with confirmed planets, $28.2\%$ exhibit RV signals that coincide with activity indicators, compared to $21.3\%$ among stars without planets; however, statistical tests show this difference is not statistically significant. Several RV signals previously attributed to planets, such as those in HIP7240, HIP28460, and HIP48331, are instead likely caused by stellar activity, emphasising the importance of using multiple diagnostics to assess RV variability. We report rotation periods in 125 stars, including 30 new estimates, and detect magnetic activity cycles in 127 stars, 95 of which are new. We further investigate the relationship between rotation and magnetic cycle periods in the context of stellar dynamo theory. The full sample reveals a continuous distribution in the $P_{\rm rot}/P_{\rm cyc}$, Rossby number diagram, lacking the classical division into active and inactive branches and instead showing a negative slope, in contrast to some earlier studies. Interestingly, stars with planetary companions exhibit a steeper trend (slope of $-1.049 \pm 0.078$) compared to non-hosts ($-0.654 \pm 0.056$), suggesting that the presence of planets may subtly influence the host star's magnetic behaviour.