On Differential Rotation and Overshooting in Solar-like Stars

We seek to characterize how the change of global rotation rate influences the overall dynamics and large-scale flows arising in the convective envelopes of stars covering stellar spectral types from early G to late K. We do so through numerical simulations with the ASH code, where we consider stella...

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Bibliographic Details
Published in:The Astrophysical journal 2017-02, Vol.836 (2), p.192
Main Authors: Brun, Allan Sacha, Strugarek, Antoine, Varela, Jacobo, Matt, Sean P., Augustson, Kyle C., Emeriau, Constance, DoCao, Olivier Long, Brown, Benjamin, Toomre, Juri
Format: Article
Language:English
Subjects:
Ashes
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Computer simulation
COMPUTERIZED SIMULATION
CONVECTION
Differential rotation
Equator
hydrodynamics
Jupiter
MAIN SEQUENCE STARS
Meridional flow
Mixing length
Morphology
Numerical simulations
Poles
Rossby number
ROTATION
STAR EVOLUTION
Stars
stars: activity
stars: rotation
stars: solar-type
Stellar envelopes
Stellar evolution
Stellar mass
Stellar rotation
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Summary:We seek to characterize how the change of global rotation rate influences the overall dynamics and large-scale flows arising in the convective envelopes of stars covering stellar spectral types from early G to late K. We do so through numerical simulations with the ASH code, where we consider stellar convective envelopes coupled to a radiative interior with various global properties. As solar-like stars spin down over the course of their main sequence evolution, such a change must have a direct impact on their dynamics and rotation state. We indeed find that three main states of rotation may exist for a given star: anti-solar-like (fast poles, slow equator), solar-like (fast equator, slow poles), or a cylindrical rotation profile. Under increasingly strict rotational constraints, the last profile can further evolve into a Jupiter-like profile, with alternating prograde and retrograde zonal jets. We have further assessed how far the convection and meridional flows overshoot into the radiative zone and investigated the morphology of the established tachocline. Using simple mixing length arguments, we are able to construct a scaling of the fluid Rossby number , which we calibrate based on our 3D ASH simulations. We can use this scaling to map the behavior of differential rotation versus the global parameters of stellar mass and rotation rate. Finally, we isolate a region on this map (Rof 1.5-2) where we posit that stars with an anti-solar differential rotation may exist in order to encourage observers to hunt for such targets.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa5c40