On the Origin of Solar Torsional Oscillations and Extended Solar Cycle

Пипин, В. В.; Kosovichev, A. G.

doi:10.3847/1538-4357/ab5952

Cited by 27 publications

(12 citation statements)

References 60 publications

(61 reference statements)

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“…The actual differences may lie somewhere in between the large variations inferred in the two models. To that end we test the feasibly of discerning between deep and shallow single-cell as well as double-cell profiles of meridional circulation, generated by the same mean-field model, operating with minimal parameter changes (K1 in Pipin & Kosovichev (2018) -referred to as M2 in their paper; M1 & M2 in Pipin & Kosovichev (2019)). Using the GALE code (Stejko et al 2021) to simulate the stochastic excitation of acoustic modes throughout the convective interior, we apply the deep focusing method to measure the resulting travel-time differences.…”

Section: Discussionmentioning

confidence: 99%

“…The first is a single-cell meridional circulation model with a deep return flow situated near the base of the tachocline -based on the mean-field model of Kichatinov (2004) and described as model M2 in Pipin & Kosovichev (2018); in this paper we will refer to this model as K1 in order to avoid confusion. The next two are a shallow single-cell, with return flow at approximately 0.80R , and a double-cell meridional circulation profile referred to as M1 and M2 respectively in Pipin & Kosovichev (2019). These meridional velocities are used as the background terms (ũ r ,ũ θ ) in our governing equations (1-3).…”

Section: Meridional Profilesmentioning

confidence: 99%

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Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation

Stejko,

Kosovichev,

Pipin

2021

Preprint

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Using a 3D global solver of the linearized Euler equations, we model acoustic oscillations over background velocity flow fields of single-cell meridional circulation with deep and shallow return flows as well as a double-cell meridional circulation profile. The velocities are generated using a mean-field hydrodynamic and dynamo model -moving through the regimes with minimal parameter changes; counter-rotation near the base of the tachocline is induced by sign inversion of the non-diffusive action of turbulent Reynolds stresses (Λ-effect) due to the radial inhomogeneity of the Coriolis number. By mimicking the stochastic excitation of resonant modes in the convective interior, we simulate realization noise present in solar observations. Using deep-focusing to analyze differences in travel-time signatures between the three regimes, as well as comparing to solar observations, we show that current helioseismology techniques may offer important insights about the location of the return flow, however, that it may not be possible to definitively distinguish between profiles of single-cell or double-cell meridional circulation.

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Section: Discussionmentioning

confidence: 99%

Section: Meridional Profilesmentioning

confidence: 99%

Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation

Stejko,

Kosovichev,

Pipin

2021

Preprint

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“…45 the data now show the first indications of the appearance of cycle 25. The physical origin of these zonal flows is so far not understood, although mean-field dynamo models have reproduced some aspects of the flows, including the high-latitude branch (e.g., Rempel 2007Rempel , 2012Pipin and Kosovichev 2019). Basu and Antia (2019) also studied the time variation of solar rotation over cycles 23 and 24.…”

Section: Temporal Changes Of the Solar Interiormentioning

confidence: 99%

Solar structure and evolution

Christensen‐Dalsgaard

2021

Living Rev Sol Phys

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The Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

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“…We are using the same formulation for the mean electromotive force as in the recent paper by Pipin & Kosovichev (2019):…”

Section: A Nonaxisymmetric Dynamo Modelmentioning

confidence: 99%

“…The standard part of E (A) i contains contributions of the α-effect tensor, αij, the antisymmetric tensor γij accounts for the turbulent pumping of the large-scale magnetic fields due to the effects of the global rotation and density stratification, and η ijk is the eddy magnetic diffusivity tensor. This corresponds to the expression of the mean electromotive force employed in the mean-field dynamo models of Pipin & Kosovichev (2019, 2020. The further details concerning E (A) i can be found in the above-cited papers.…”

Section: A Nonaxisymmetric Dynamo Modelmentioning

confidence: 99%

Solar large-scale magnetic field and cycle patterns in solar dynamo

Obridko,

Pipin,

Sokoloff

et al. 2021

Preprint

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We compare spectra of the zonal harmonics of the large-scale magnetic field of the Sun using observation results and solar dynamo models. The main solar activity cycle as recorded in these tracers is a much more complicated phenomenon than the eigen solution of solar dynamo equations with the growth saturated by a back reaction of the dynamo-driven magnetic field on solar hydrodynamics. The nominal 11( 22)-year cycle as recorded in each mode has a specific phase shift varying from cycle to cycle; the actual length of the cycle varies from one cycle to another and from tracer to tracer. Both the observation and the dynamo model show an exceptional role of the axisymmetric 5 mode. Its origin seems to be readily connected with the formation and evolution of sunspots on the solar surface. The results of observations and dynamo models show a good agreement for the low 1 and 3 modes. The results for these modes do not differ significantly for the axisymmetric and nonaxisymmetric models. Our findings support the idea that the sources of the solar dynamo arise as a result of both the distributed dynamo processes in the bulk of the convection zone and the surface magnetic activity.

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On the Origin of Solar Torsional Oscillations and Extended Solar Cycle

Cited by 27 publications

References 60 publications

Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation

Forward Modeling Helioseismic Signatures of One- and Two-cell Meridional Circulation

Solar structure and evolution

Solar large-scale magnetic field and cycle patterns in solar dynamo

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