2D dynamics of the radiative core of low mass stars

Abstract

Understanding the internal rotation of low mass stars all along their evolution is of primary interest when studying their rotational dynamics, internal mixing and magnetic field generation. In this context, helio- and asteroseismology probe angular velocity gradients deep within solar type stars at different evolutionary stages. Still the rotation close to the center of such stars on the main sequence is hardly detectable and the dynamical interaction of the radiative core with the surface convective envelope is not well understood. For instance, the influence of the differential rotation profile sustained by convection and applied as a boundary condition to the radiation zone is very important in the formation of tachoclines. In this work, we study a 2D hydrodynamical model of a radiative core when an imposed, solar or anti-solar, differential rotation is applied at the upper boundary. This model uses the Boussinesq approximation and we find that the shear induces a cylindrical differential rotation associated with a unique cell of meridional circulation in each hemisphere (counterclockwise when the shear is solar-like and clockwise when it is anti-solar). The results are discussed in the framework of seismic observables (internal rotation rate, core-to-surface rotation ratio) while perspectives to improve our modeling by including magnetic field or transport by internal gravity waves will be discussed.

5 pages, 4 figures. To appear in the proceedings of "Seismology of the Sun and the Distant Stars 2016, Joint TASC2 & KASC9 Workshop - SPACEINN & HELAS8 Conference" (ed. Mário J. P. F. G. Monteiro, Margarida S. Cunha, João Miguel T. Ferreira ), Azores, Portugal, 11-15 July 2016

References in corpus (8)

• Magnetic confinement of the solar tachocline
• Measuring the extent of convective cores in low-mass stars using Kepler data: towards a calibration of core overshooting
• Magnetic confinement of the solar tachocline: II. Coupling to a convection zone
• The Solar-Stellar Connection
• The dynamics of the radiative envelope of rapidly rotating stars. I. A spherical Boussinesq model
• On the dynamics of radiative zones in rotating stars
• Dynamics of the radiative envelope of rapidly rotating stars: Effects of spin-down driven by mass loss
• Dynamics of the envelope of a rapidly rotating star or giant planet in gravitational contraction