What sets the magnetic field strength and cycle period in solar-type stars?

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dc.creatorGustavo Andres Guerrero Eraso
dc.creatorBonnie Romano Zaire
dc.creatorPiotr Krzysztof Smolarkiewicz
dc.creatorElisabete Maria de Gouveia Dal Pino
dc.creatorAlexander G. Kosovichev
dc.creatorNagi Nicolas Mansour
dc.date.accessioned2023-11-13T15:49:18Z
dc.date.accessioned2025-09-08T23:31:51Z
dc.date.available2023-11-13T15:49:18Z
dc.date.issued2019
dc.description.sponsorshipCNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
dc.description.sponsorshipFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
dc.description.sponsorshipFAPESP - Fundação de Amparo à Pesquisa do Estado de São Paulo
dc.format.mimetypepdf
dc.identifier.doihttps://doi.org/10.3847/1538-4357/ab224a
dc.identifier.issn1538-4357
dc.identifier.urihttps://hdl.handle.net/1843/60866
dc.languageeng
dc.publisherUniversidade Federal de Minas Gerais
dc.relation.ispartofThe Astrophysical Journal
dc.rightsAcesso Aberto
dc.subjectEstrelas
dc.subjectCampos magnéticos
dc.subject.otherDynamo
dc.subject.otherStars
dc.subject.otherMagnetic field
dc.titleWhat sets the magnetic field strength and cycle period in solar-type stars?
dc.typeArtigo de periódico
local.citation.epage20
local.citation.issue1
local.citation.spage1
local.citation.volume880
local.description.resumoTwo fundamental properties of stellar magnetic fields have been determined by observations for solar-like stars with different Rossby numbers (Ro), namely, the magnetic field strength and the magnetic cycle period. The field strength exhibits two regimes: (1) for fast rotation, it is independent of Ro, and (2) for slow rotation, it decays with Ro following a power law. For the magnetic cycle period, two regimes of activity, the active and inactive branches, have also been identified. For both of them, the longer the rotation period, the longer the activity cycle. Using global dynamo simulations of solar-like stars with Rossby numbers between ∼0.4 and ∼2, this paper explores the relevance of rotational shear layers in determining these observational properties. Our results, consistent with nonlinear a W2 dynamos, show that the total magnetic field strength is independent of the rotation period. Yet at surface levels, the origin of the magnetic field is determined by Ro. While for Ro 1, it is generated in the convection zone, for Ro 1, strong toroidal fields are generated at the tachocline and rapidly emerge toward the surface. In agreement with the observations, the magnetic cycle period increases with the rotational period. However, a bifurcation is observed for ~Ro 1, separating a regime where oscillatory dynamos operate mainly in the convection zone from the regime where the tachocline has a predominant role. In the latter, the cycles are believed to result from the periodic energy exchange between the dynamo and the magneto-shear instabilities developing in the tachocline and the radiative interior.
local.identifier.orcidhttps://orcid.org/0000-0002-2671-8796
local.identifier.orcidhttps://orcid.org/0000-0002-9328-9530
local.identifier.orcidhttps://orcid.org/0000-0001-7077-3285
local.identifier.orcidhttps://orcid.org/0000-0001-8058-4752
local.identifier.orcidhttps://orcid.org/0000-0003-0364-4883
local.identifier.orcidhttps://orcid.org/0000-0002-3927-3917
local.publisher.countryBrasil
local.publisher.departmentICX - DEPARTAMENTO DE FÍSICA
local.publisher.initialsUFMG
local.url.externahttps://iopscience.iop.org/article/10.3847/1538-4357/ab224a

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