Projects per year
Abstract
Context. Results from global magnetoconvection simulations of solar-like
stars are at odds with observations in many respects: They 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
non-axisymmetric 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,
on a semi-global spherical setup describing 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
non-axisymmetric transition point is shifted towards higher rotation
rates. We also find a change in the propagation direction of ADWs so
that also prograde waves are now found. The transition from anti-solar
to solar-like rotation profile, however, is also shifted towards higher
rotation rates, leaving the models into an even more unrealistic regime.
Conclusions. Although a 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 match better with
observations.
Original language | English |
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Article number | A141 |
Journal | Astronomy & Astrophysics |
Volume | 645 |
Early online date | 1 Jun 2020 |
DOIs | |
Publication status | Published - Jan 2021 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Astrophysics - Solar and Stellar Astrophysics
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Projects
- 1 Active
-
UniSDyn: Building up a Unified Theory of Stellar Dynamos
Käpylä, M., Rheinhardt, M. & Pekkilä, J.
01/01/2020 → 30/04/2024
Project: EU: ERC grants