Global oscillations in a magnetic solar modelII Oblique propagation

TY - JOUR

T1 - Global oscillations in a magnetic solar model

T2 - II Oblique propagation

AU - Pintér, Balázs

AU - Erdélyi, R.

AU - Goossens, M.

N1 - Pintér, B.; Erdélyi, R.; Goossens, M., Global oscillations in a magnetic solar model. II. Oblique propagation, Astronomy and Astrophysics, Volume 466, Issue 1, April IV 2007, pp.377-388 Pintér, B.; Erdélyi, R.; Goossens, M., (2007) 'Global oscillations in a magnetic solar model II. Oblique propagation', Astronomy and Astrophysics 466(1) pp.377-388 RAE2008

PY - 2007/4

Y1 - 2007/4

N2 - The coupling of solar global acoustic oscillations to a magnetised solar atmosphere is studied here. The solar interior - atmosphere interface is modelled by a non-magnetic polytrope interior overlayed by a planar atmosphere embedded in non-uniform horizontal atmospheric magnetic field. Pintér & Goossens (1999, A&A, 347, 321) showed that parallel propagating acoustic waves can couple resonantly to local magnetohydrodynamic (MHD) slow continuum modes only. In general, global acoustic modes can, however, propagate in arbitrary directions with respect to local atmospheric fields giving rise to an additional efficient coupling mechanism that has consequences on mode damping and atmospheric energetics. In this paper we study obliquely propagating global modes that can couple also to local MHD Alfvén continuum modes. The atmospheric magnetic effects on global mode frequencies are still much of a debate. In particular, the resulting frequency shifts and damping rates of global modes caused by the resonant interaction with both local Alfvén and slow waves are investigated. We found the coupling of global f and p modes and the Lamb mode, that penetrate into the magnetic solar atmosphere, will strongly depend on the direction of propagation with respect to the solar atmospheric magnetic field. These frequency shifts, as a function of the propagation direction, give us a further elegant tool and refinement method of local helioseismology techniques. Finally we briefly discuss the importance of studying obliquely propagating waves and discuss the results in the context of possible helioseismic observations.

AB - The coupling of solar global acoustic oscillations to a magnetised solar atmosphere is studied here. The solar interior - atmosphere interface is modelled by a non-magnetic polytrope interior overlayed by a planar atmosphere embedded in non-uniform horizontal atmospheric magnetic field. Pintér & Goossens (1999, A&A, 347, 321) showed that parallel propagating acoustic waves can couple resonantly to local magnetohydrodynamic (MHD) slow continuum modes only. In general, global acoustic modes can, however, propagate in arbitrary directions with respect to local atmospheric fields giving rise to an additional efficient coupling mechanism that has consequences on mode damping and atmospheric energetics. In this paper we study obliquely propagating global modes that can couple also to local MHD Alfvén continuum modes. The atmospheric magnetic effects on global mode frequencies are still much of a debate. In particular, the resulting frequency shifts and damping rates of global modes caused by the resonant interaction with both local Alfvén and slow waves are investigated. We found the coupling of global f and p modes and the Lamb mode, that penetrate into the magnetic solar atmosphere, will strongly depend on the direction of propagation with respect to the solar atmospheric magnetic field. These frequency shifts, as a function of the propagation direction, give us a further elegant tool and refinement method of local helioseismology techniques. Finally we briefly discuss the importance of studying obliquely propagating waves and discuss the results in the context of possible helioseismic observations.

U2 - 10.1051/0004-6361:20041632

DO - 10.1051/0004-6361:20041632

M3 - Article

VL - 466

SP - 377

EP - 388

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 1

ER -