On the origin of the dichotomy of stellar activity cycles

Abstract

The presence of possible correlations between stellar rotation rate $\Omega$ and the frequency of the activity cycle ${\omega }_{\mathrm{cyc}}$ is still much debated. We implement a new Bayesian classification algorithm based on a simultaneous regression analysis of multiple scaling laws and we demonstrate the existence of two different scalings in the ${\log }_{10}{\omega }_{\mathrm{cyc}}$ -- ${\log }_{10}\Omega$ plane for an extended Mt.~Wilson sample of 67 stars. Thanks to metallicity measurements obtained from both ESA Gaia and high-resolution spectroscopy, we argue that the origin of this dichotomy is likely related to the chemical composition: stars whose magnetic cycle frequency increases with rotation rate are less metallic than stars whose magnetic cycle frequency decreases with stellar rotation rates. On the contrary, no clear difference in chromospheric magnetic activity indicators characterizes the two branches.

7 pages, 2 figures, 1 table. Accepted for publication in The Astrophysical Journal Letters. Contact e-mails: [email protected], [email protected]

References in corpus (11)

• The Gaia mission
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G=18.5
• Abundances in the Local Region II: F, G and K Dwarfs and Subgiants
• Stellar chromospheric activity of 1,674 FGK stars from the AMBRE-HARPS sample I. A catalogue of homogeneous chromospheric activity
• DIAMONDS: a new Bayesian Nested Sampling tool. Application to Peak Bagging of solar-like oscillations
• The radii of the nearby K5V and K7V stars 61 Cyg A & B - CHARA/FLUOR interferometry and CESAM2k modeling
• A calibration of the Rossby number from asteroseismology
• Activity cycles in members of young loose stellar associations
• Asteroseismic stellar activity relations

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• Expanding the frontiers of cool-dwarf asteroseismology with ESPRESSO. Detection of solar-like oscillations in the K5 dwarf $\epsilon$ Indi
• Kepler main-sequence solar-like stars: surface rotation and magnetic-activity evolution
• Luminaries in the Sky: The TESS Legacy Sample of Bright Stars. I. Asteroseismic detections in naked-eye main-sequence and sub-giant solar-like oscillators
• Magnetohydrodynamic simulations of A-type stars: Long-term evolution of core dynamo cycles
• Predicting Stellar Rotation Periods Using XGBoost