Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani

Abstract

The active K2 dwarf epsilon Eri has been extensively characterized, both as a young solar analog and more recently as an exoplanet host star. As one of the nearest and brightest stars in the sky, it provides an unparalleled opportunity to constrain stellar dynamo theory beyond the Sun. We confirm and document the 3 year magnetic activity cycle in epsilon Eri originally reported by Hatzes and coworkers, and we examine the archival data from previous observations spanning 45 years. The data show coexisting 3 year and 13 year periods leading into a broad activity minimum that resembles a Maunder minimum-like state, followed by the resurgence of a coherent 3 year cycle. The nearly continuous activity record suggests the simultaneous operation of two stellar dynamos with cycle periods of 2.95+/-0.03 years and 12.7+/-0.3 years, which by analogy with the solar case suggests a revised identification of the dynamo mechanisms that are responsible for the so-called "active" and "inactive" sequences as proposed by Bohm-Vitense. Finally, based on the observed properties of epsilon Eri we argue that the rotational history of the Sun is what makes it an outlier in the context of magnetic cycles observed in other stars (as also suggested by its Li depletion), and that a Jovian-mass companion cannot be the universal explanation for the solar peculiarities.

6 pages, 3 figures, 1 table, ApJ Letters (accepted)

References in corpus (9)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Magnetic Cycles in a Convective Dynamo Simulation of a Young Solar-type Star
• The Extrasolar Planet epsilon Eridani b - Orbit and Mass
• Lithium depletion and the rotational history of exoplanet host stars
• Rapidly Rotating Suns and Active Nests of Convection
• Excitation of solar-like oscillations across the HR diagram
• Discovery of a 1.6-year Magnetic Activity Cycle in the Exoplanet Host Star iota Horologii
• HIP 56948: A Solar Twin With a Low Lithium Abundance
• Mg II h + k emission lines as stellar activity indicators of main sequence F-K stars

Cited by in corpus (37)

• Asteroseismology of solar-type stars
• The connection between stellar activity cycles and magnetic field topology
• Astrometry with Hubble Space Telescope Fine Guidance Sensors - A Review
• Constraining the Physical Properties of Stellar Coronal Mass Ejections with Coronal Dimming: Application to Far Ultraviolet Data of $\epsilon$ Eridani
• The relation between stellar magnetic field geometry and chromospheric activity cycles I: The highly variable field of Epsilon Eridani at activity minimum
• Multi-instrumental view of magnetic fields and activity of $\epsilon$ Eridani with SPIRou, NARVAL, and TESS
• Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions
• A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
• The crucial role of surface magnetic fields for stellar dynamos: Epsilon Eridani, 61 Cygni A, and the Sun
• A possible long-term activity cycle for ι Horologii: First results from the HKα & SPI-HKα projects
• Influence of the Sun-like magnetic cycle on exoplanetary atmospheric escape
• Temporal variation of the photometric magnetic activity for the Sun and Kepler solar-like stars
• MAMBO image of the debris disk around epsilon Eridani : robustness of the azimuthal structure
• Coronal mass ejections and type II radio emission variability during a magnetic cycle on the solar-type star $\epsilon$ Eridani
• EXPRES. III. Revealing the Stellar Activity Radial Velocity Signature of $\epsilon$ Eridani with Photometry and Interferometry
• Coronal X-Ray Emission from Nearby, Low-Mass, Exoplanet Host Stars Observed by the MUSCLES and Mega-MUSCLES HST Treasury Survey Projects
• Magnetic field measurements of $\epsilon$ Eridani from Zeeman broadening
• The Effect of Magnetic Variability on Stellar Angular Momentum Loss II: The Sun, 61 Cygni A, $\epsilon$ Eridani, $\xi$ Bootis A and $\tau$ Bootis A
• Time evolution of magnetic activity cycles in young suns: The curious case of kappa Ceti
• Numerical quantification of the wind properties of cool main sequence stars
• Solar and stellar activity cycles -- no synchronization with exoplanets
• The lost sunspot cycle: New support from Be10 measurements
• A BCool survey of stellar magnetic cycles
• The multi-line slope method for the measure of the effective magnetic field of the cool stars: an application to the solar like cycle of ε Eri
• UVMag: stellar formation, evolution, structure and environment with space UV and visible spectropolarimetry
• Stellar activity with LAMOST. III. Temporal variability pattern in Pleiades, Praesepe, and Hyades
• The impact of unresolved magnetic spots on high precision radial velocity measurements
• A multi-wavelength view of the multiple activity cycles of $\epsilon$~Eridani
• Variability of Known Exoplanet Host Stars Observed by TESS
• Testing the Rossby Paradigm: Weakened Magnetic Braking in early K-type Stars
• An application of a solar-type dynamo model for Epsilon Eridani
• SPHERE RefPlanets: Search for epsilon Eridani b and warm dust
• Understanding the Radio Emission from $\epsilon$ Eridani
• The active RS CVn-type system SZ Pictoris
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• Far beyond the Sun: III. The magnetic cycle of $\mathbf{\iota }$ Horologii
• Activity-rotation in the dM4 star Gl 729. A possible chromospheric cycle