Dataset for 'Rotational dependence of turbulent transport coefficients in global convective dynamo simulations of solar-like stars'

<p>For moderate and slow rotation, magnetic activity of solar-like stars&nbsp;is observed to strongly depend on rotation,&nbsp;while for rapid rotation, only a very weak or no dependency is&nbsp;detected.&nbsp;These observations do not yet have a solid explanation in terms of dynamo theory.&nbsp;To work towards such an explanation,&nbsp;we numerically&nbsp;investigated the rotational dependency of dynamo&nbsp;drivers in solar-like stars, that is, stars that have a convective envelope of similar thickness as in the Sun.&nbsp;We ran semi-global convection simulations of stars with rotation&nbsp;rates from 0 to 30 times the solar value, corresponding to Coriolis numbers, Co, of 0 to 110. We measured the turbulent transport coefficients describing the magnetic field evolution with&nbsp;the help of the &nbsp;test-field method,&nbsp;and compared with the dynamo effect arising from the differential rotation, self-consistently generated in the models.&nbsp;The trace of the&nbsp;<strong><span class="math-tex">\(\alpha\)</span></strong> tensor increases for moderate rotation rates with Co^0.5&nbsp;and levels off for rapid rotation.&nbsp;This behavior is in agreement with&nbsp;the kinetic <span class="math-tex">\(\alpha\)</span>&nbsp;based on the kinetic helicity, if one&nbsp;takes into account the decrease of the convective scale&nbsp;with increasing rotation.&nbsp;The <strong><span class="math-tex">\(\alpha\)</span></strong>&nbsp;tensor&nbsp;becomes highly anisotropic for Co &gt;&nbsp;1,&nbsp;<span class="math-tex">\(\alpha_{rr}\)</span>&nbsp;dominates&nbsp;for moderate rotation (1&lt;Co&lt;10), and <span class="math-tex">\(\alpha_{\phi\phi}\)</span>&nbsp;for rapid rotation&nbsp;(Co &gt; 10). The effective meridional flow, taking into account the&nbsp;turbulent pumping effects, is markedly different from the actual meridional circulation profile. Hence, the turbulent pumping effect is&nbsp;dominating the &nbsp;meridional&nbsp;transport of the magnetic field.&nbsp;Taking all dynamo effects into account, we find three distinct regimes. For slow rotation, the&nbsp;<span class="math-tex">\(\alpha\)</span>&nbsp;and R&auml;dler effects are dominating in presence of anti-solar&nbsp;differential rotation.&nbsp;For moderate rotation,&nbsp;<span class="math-tex">\(\alpha\)</span>&nbsp;and <span class="math-tex">\(\Omega\)</span>&nbsp;effects are&nbsp;dominant, indicative of <span class="math-tex">\(\alpha\Omega\)</span>&nbsp; or <span class="math-tex">\(\alpha^2\Omega\)</span>&nbsp;dynamos in operation,&nbsp;producing equatorward-migrating dynamo waves with the qualitatively solar-like rotation profile. For rapid rotation, an&nbsp;<span class="math-tex">\(\alpha^2\)</span>&nbsp;mechanism, with an influence from the R&auml;dler&nbsp;effect, appears to be the most probable driver of the dynamo. Our study reveals the presence of a large variety of dynamo effects beyond the classical <span class="math-tex">\(\alpha\Omega\)</span>&nbsp;mechanism, which need to be investigated further to fully understand the dynamos of solar-like stars.&nbsp;The highly anisotropic <strong><span class="math-tex">\(\alpha\)</span></strong>&nbsp;tensor might be the primary&nbsp;reason for the change of axisymmetric to non-axisymmetric dynamo solutions in the moderate rotation regime.</p> <p>For the full article see&nbsp;<a href="https://arxiv.org/abs/1910.06776">https://arxiv.org/abs/1910.06776</a></p>