TY - JOUR

T1 - MHD wave propagation in the neighbourhood of two null points

AU - McLaughlin, James

AU - Hood, Alan William

PY - 2005/5

Y1 - 2005/5

N2 - The nature of fast magnetoacoustic and Alfvén waves is investigated in a zero β plasma in the neighbourhood of a pair of two-dimensional null points. This gives an indication of wave propagation in the low β solar corona, for a more complicated magnetic configuration than that looked at by McLaughlin & Hood (2004, A&A, 420, 1129). It is found that the fast wave is attracted to the null points and that the front of the wave slows down as it approaches the null point pair. Here, the wave splits and part of the wave accumulates at one null and the rest at the other. Current density will then accumulate at these points and ohmic dissipation will then extract the energy in the wave at these points. This suggests locations where wave heating will occur in the corona. The Alfvén wave behaves in a different manner in that the wave accumulates along the separatrices. Hence, the current density will accumulate at this part of the topology and this is where wave heating will occur. However, the phenomenon of wave accumulation at a specific place is a feature of both wave types, and illustrates the importance of studying the topology of the corona when considering MHD wave propagation.

AB - The nature of fast magnetoacoustic and Alfvén waves is investigated in a zero β plasma in the neighbourhood of a pair of two-dimensional null points. This gives an indication of wave propagation in the low β solar corona, for a more complicated magnetic configuration than that looked at by McLaughlin & Hood (2004, A&A, 420, 1129). It is found that the fast wave is attracted to the null points and that the front of the wave slows down as it approaches the null point pair. Here, the wave splits and part of the wave accumulates at one null and the rest at the other. Current density will then accumulate at these points and ohmic dissipation will then extract the energy in the wave at these points. This suggests locations where wave heating will occur in the corona. The Alfvén wave behaves in a different manner in that the wave accumulates along the separatrices. Hence, the current density will accumulate at this part of the topology and this is where wave heating will occur. However, the phenomenon of wave accumulation at a specific place is a feature of both wave types, and illustrates the importance of studying the topology of the corona when considering MHD wave propagation.

UR - http://adsabs.harvard.edu/abs/2005A%26A...435..313M

U2 - 10.1051/0004-6361:20042361

DO - 10.1051/0004-6361:20042361

M3 - Article

VL - 435

SP - 313

EP - 325

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 1

ER -