Physically motivated heat conduction treatment in simulations of solar-like stars: effects on dynamo transitions

M. Viviani, M. J. Käpylä

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

1 Sitaatiot (Scopus)
5 Lataukset (Pure)

Abstrakti

Context. Results from global magnetoconvection simulations of solar-like stars are at odds with observations in many respects: Simulations show a surplus of energy in the kinetic power spectrum at large scales; anti-solar differential rotation profiles with accelerated poles, and a slow equator for the solar rotation rate; and a transition from axi-to nonaxisymmetric dynamos at a much lower rotation rate than what is observed. Even though the simulations reproduce the observed active longitudes in fast rotators, their motion in the rotational frame (the so-called azimuthal dynamo wave, ADW) is retrograde, in contrast to the prevalent prograde motion in observations. Aims. We study the effect of a more realistic treatment of heat conductivity in alleviating the discrepancies between observations and simulations. Methods. We use physically motivated heat conduction by applying Kramers opacity law to a semi-global spherical setup that describes the convective envelopes of solar-like stars, instead of a prescribed heat conduction profile from mixing-length arguments. Results. We find that some aspects of the results now better correspond to observations: The axi-to nonaxisymmetric transition point is shifted towards higher rotation rates. We also find a change in the propagation direction of ADWs that means that prograde waves are also now found. However, the transition from an anti-solar to solar-like rotation profile is also shifted towards higher rotation rates, leaving the models in an even more unrealistic regime. Conclusions. Although Kramers-based heat conduction does not help in reproducing the solar rotation profile, it does help in the faster rotation regime, where the dynamo solutions now better match the observations.

AlkuperäiskieliEnglanti
ArtikkeliA141
JulkaisuAstronomy & Astrophysics
Vuosikerta645
Varhainen verkossa julkaisun päivämäärä1 kesäkuuta 2020
DOI - pysyväislinkit
TilaJulkaistu - 1 tammikuuta 2021
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

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