Astron. Astrophys. 364, 876-878 (2000)

Research Note

Shear turbulence beneath the solar tachocline

E. Schatzman ¹, J.-P. Zahn ¹ and P. Morel <sup>2

1</sup> DASGAL, UMR CNRS 8633, Observatoire de Paris, Section de Meudon, 92195 Meudon CEDEX, France
² Département Cassini, UMR CNRS 6529, Observatoire de la Côte d'Azur, B.P. 4229, 06304 Nice CEDEX 4, France

Received 19 July 2000 / Accepted 24 October 2000

Abstract

Helioseismic inversions of the Sun's internal angular velocity profile show that the rotation changes from differential in latitude in the convection zone to almost uniform in the radiative region below. The transition occurs in a thin layer, the tachocline, which is the seat of strong shear in the vertical direction. In this Note we examine whether this rotation profile can lead to shear turbulence at the top of the radiation zone. By using the standard solar model, we show that such turbulence can be generated only in a narrow region at the equator and even in narrower layers at higher latitudes. We conclude that the turbulence generated by this vertical shear is unlikely to play a significant role in the transport of matter and angular momentum, and that other mechanisms must be invoked to achieve this.

Key words: convection turbulence Sun: evolution Sun: interior Sun: rotation

Send offprint requests to: E. Schatzman

Correspondence to: Evry.Schatzman@obspm.fr

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. The solar rotation profile
• 3. Conditions for vertical shear instability
  • 3.1. Richardson criterion
  • 3.2. Critical Reynolds number
• 4. The turbulent region in the Sun
• 5. Results and discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001
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