TY - JOUR

T1 - Damping of helioseismic modes in steady state

AU - Pintér, B.

AU - Erdélyi, R.

AU - New, R.

N1 - Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.

PY - 2001

Y1 - 2001

N2 - The effects of an equilibrium flow in the internal regions of the Sun are studied on the damping of helioseismic f- and p-modes. The Sun is modeled as a multi-layered plasma, where the upper parts, representing the chromosphere and corona, are embedded in a horizontally unidirectional though vertically inhomogeneous magnetic field, while the lower part, representing the sub-photospheric polytropic region, is in a steady equilibrium state. The steady state sub-surface region can be considered as a first approximation of dynamic motions (e.g., differential rotation, sub-surface flows, meridional flows, convective motion, etc.). The frequencies and the line-widths of eigenmodes are affected by sub-surface flow and atmospheric magnetic fields. A key contribution to the effects comes from the universal mechanism of resonant absorption. When both atmospheric magnetic field and sub-surface flows are present, a complex picture of competition between these two effects is found. The theoretically predicted frequency shifts in a steady state show promise of explaining the observed effects. Changes in damping of f- and p-modes caused by changes (e.g. cyclic, if any) of steady state flows are predicted.

AB - The effects of an equilibrium flow in the internal regions of the Sun are studied on the damping of helioseismic f- and p-modes. The Sun is modeled as a multi-layered plasma, where the upper parts, representing the chromosphere and corona, are embedded in a horizontally unidirectional though vertically inhomogeneous magnetic field, while the lower part, representing the sub-photospheric polytropic region, is in a steady equilibrium state. The steady state sub-surface region can be considered as a first approximation of dynamic motions (e.g., differential rotation, sub-surface flows, meridional flows, convective motion, etc.). The frequencies and the line-widths of eigenmodes are affected by sub-surface flow and atmospheric magnetic fields. A key contribution to the effects comes from the universal mechanism of resonant absorption. When both atmospheric magnetic field and sub-surface flows are present, a complex picture of competition between these two effects is found. The theoretically predicted frequency shifts in a steady state show promise of explaining the observed effects. Changes in damping of f- and p-modes caused by changes (e.g. cyclic, if any) of steady state flows are predicted.

KW - Sun: atmosphere

KW - Sun: helioseismology

KW - Sun: interior

KW - Sun: magnetic fields

KW - Sun: oscillations

KW - Sun: rotation

UR - http://www.scopus.com/inward/record.url?scp=0035373188&partnerID=8YFLogxK

U2 - 10.1051/0004-6361:20010544

DO - 10.1051/0004-6361:20010544

M3 - Letter

AN - SCOPUS:0035373188

SN - 0004-6361

VL - 372

SP - L17-L20

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

IS - 1

ER -