An application of a solar-type dynamo model for Epsilon Eridani

Abstract

During the last decade, the relation between activity cycle periods with stellar parameters has received special attention. The construction of reliable registries of activity reveals that solar type stars exhibit activity cycles with periods from few years to decades and, in same cases, long and short activity cycles coexist suggesting that two dynamos could operate in these stars. In particular, Epsilon Eridani is an active young K2V star (0.8 Gyr), which exhibits a short and long-term chromospheric cycles of near 3 and 13-yr periods. Additionally, between 1985 and 1992, the star went through a broad activity minimum, similar to the solar Maunder Minimum-state. Motivated by these results, we found in Epsilon Eridani a great opportunity to test the dynamo theory. Based on the model developed in Sraibman & Minotti (2019), in this work we built a non linear axisymmetric dynamo for Epsilon Eridani. The time series of the simulated magnetic field components near the surface integrated in all the stellar disc exhibits both the long and short-activity cycles with periods similar to the ones detected from observations and also time intervals of low activity which could be associated to the broad Minimun. The short activity cycle associated to the magnetic reversal could be explained by the differential rotation, while the long cycle is associated to the meridional mass flows induced by the Lorentz force. In this way, we show that a single non-linear dynamo model derived from first principles with accurate stellar parameters could reproduce coexisting activity cycles.

arXiv commentAccpeted for publication in MNRAS

References in corpus (37)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The Solar Cycle
• Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• Predicting solar cycle 24 with a solar dynamo model
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• Flux-transport dynamos with Lorentz force feedback on differential rotation and meridional flow: Saturation mechanism and torsional oscillations
• Multiple and changing cycles of active stars II. Results
• Angular Momentum Loss from Cool Stars: An Empirical Expression and Connection to Stellar Activity
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• Stellar Evidence that the Solar Dynamo may be in Transition
• Discovery of a 1.6-year Magnetic Activity Cycle in the Exoplanet Host Star iota Horologii
• On the role of meridional flows in flux transport dynamo models
• Reconstruction of total solar irradiance 1974-2009
• A Solar Dynamo Model Driven by Mean-Field Alpha and Babcock-Leighton Sources: Fluctuations, Grand-Minima-Maxima and Hemispheric Asymmetry in Sunspot Cycles
• Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
• Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations
• The connection between stellar activity cycles and magnetic field topology
• Evolution of coexisting long and short period stellar activity cycles
• Magnetic Evolution and the Disappearance of Sun-like Activity Cycles
• Estimating activity cycles with probabilistic methods II. The Mount Wilson Ca H&K data
• A coupled $2\times 2$D Babcock-Leighton solar dynamo model. II. Reference dynamo solutions
• On the sensitivity of magnetic cycles in global simulations of solar-like stars
• On the long-term correlation between the flux in the Ca II H & K and Halpha lines for FGK stars
• An X-ray activity cycle on the young solar-like star $\epsilon \mathrm{Eridani}$
• A Three-Dimensional Babcock-Leighton Solar Dynamo Model: Initial Results with Axisymmetric Flows
• Sun-Like Magnetic Cycles in the Rapidly-Rotating Young Solar Analog HD 30495
• First long-term activity study of AU Microscopii: a possible chromospheric cycle
• Long-term chromospheric activity in southern M dwarfs: Gl 229 A and Gl 752 A
• Possible chromospheric activity cycles in AD Leo
• Meridional circulation dynamics from 3D MHD global simulations of solar convection
• The spectroscopic binary system Gl 375. I. Orbital parameters and chromospheric activity
• A possible long-term activity cycle for ι Horologii: First results from the HKα & SPI-HKα projects
• A theoretical model of the variation of the meridional circulation with the solar cycle
• Magnetic field measurements of $\epsilon$ Eridani from Zeeman broadening
• Evolution of Long Term Variability in Solar Analogs
• Modeling $\epsilon$ Eridani and asteroseismic tests of element diffusion

Cited by in corpus (1)

• Activity-rotation in the dM4 star Gl 729. A possible chromospheric cycle