Work

Discovery of Thermal Rossby Waves and Evidence for Weak Large-scale Convection in the Solar Interior

Year: 2026

Type: article

Abstract: Compressible Rossby waves—long predicted by theories of rotating stratified convection—offer a unique window into the dynamical structure of the solar interior. Despite their foundational status in astrophysical convection theory, they have evaded unambiguous detection for more than half a century. Analyzing nearly 15 yr of space- and ground-based helioseismic observations using normal-mode coupling, we report the discovery of a coherent, dispersive family of prograde inertial vorticity waves confined to depths below r / R ⊙ < 0.98, with amplitudes <10 cm s −1 , at spatial harmonic degrees ranging up to s ∼ 75, and oscillating at temporal frequencies comparable to the solar rotation rate. Convection drives fluid flows, which, in the parameter regime that applies to the Sun, are likely turbulent. We argue that our measurements hint at convective extinction below r / R ⊙ ∼ 0.98, thereby marking a transition from vigorous surface turbulence to rotationally constrained (Rossby number ∼10 −4 –10 −3 ), weakly turbulent (<3 m s −1 ) dynamics.

Source: The Astrophysical Journal Letters

DOI: 10.3847/2041-8213/ae3186

Author: Shravan M. Hanasoge

Institutions: Tata Institute of Fundamental Research, New York University Abu Dhabi

Language: English

Topic: Solar and Space Plasma Dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,400

Funder: Tata Institute of Fundamental Research