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

Author:

Buccino A P12,Sraibman L3,Olivar P M13,Minotti F O13

Affiliation:

1. Departamento de Física, FCEyN Universidad de Buenos Aires, Buenos Aires 1428, Argentina

2. Instituto de Astronomía y Física del Espacio (UBA-CONICET), Buenos Aires 1428, Argentina

3. Instituto de Física del Plasma (UBA-CONICET), Buenos Aires 1428, Argentina

Abstract

ABSTRACT During the last decade, the relation between activity cycle periods and 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 some cases, long and short activity cycles coexist suggesting that two dynamos could operate in these stars. In particular, ε Eridani is an active young K2V star (0.8 Gyr), which exhibits short and long-term chromospheric cycles of ∼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 ε Eridani a great opportunity to test the dynamo theory. Based on the model developed in Sraibman & Minotti, in this work we built a non-linear axisymmetric dynamo for ε 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 that could be associated with the broad Minimum. The short activity cycle associated with the magnetic reversal could be explained by the differential rotation, while the long cycle is associated with 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.

Funder

Consejo Nacional de Investigaciones Científicas y Técnicas

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 3 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Sun-as-a-star variability of Hα and Ca II 854.2 nm lines;Frontiers in Astronomy and Space Sciences;2024-01-08

2. Large-scale dynamo model for accretion disks;Astronomy & Astrophysics;2022-10

3. Activity–rotation in the dM4 star Gl 729;Astronomy & Astrophysics;2020-11-24

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