Alfvén Waves in the Lower Solar Atmosphere
David B. Jess,1,2*
Philip J. Crockett,1 Francis
P. Keenan,1 Damian J.
The flow of energy through the solar atmosphere
and the heating of the Sun's outer
regions are still not understood. Here, we
report the detection of oscillatory phenomena
associated with a large bright-point
group that is 430,000 square kilometers
in area and located near the solar disk center.
Wavelet analysis reveals full-width half-maximum
oscillations with periodicities ranging
from 126 to 700 seconds originating above the bright
point and significance levels exceeding 99%.
These oscillations, 2.6 kilometers per
second in amplitude, are coupled with chromospheric
line-of-sight Doppler velocities with an
average blue shift of 23 kilometers per
second. A lack of cospatial intensity oscillations
and transversal displacements rules out the
presence of magneto-acoustic wave modes.
The oscillations are a signature of Alfvén
waves produced by a torsional twist of ±22
degrees. A phase shift of 180 degrees
across the diameter of the bright point
suggests that these torsional Alfvén oscillations
are induced globally throughout the entire
brightening. The energy flux associated
with this wave mode is sufficient to heat
the solar corona.
Astrophysics Research Centre,
School of Mathematics and Physics, Queen's
University, Belfast, BT7 1NN, Northern Ireland, UK.
2 Solar Physics Laboratory, NASA Goddard
Space Flight Center, Code 671, Greenbelt, MD 20771,
3 Solar Physics and Space Plasma Research
Centre, University of Sheffield, Hicks Building,
Hounsfield Road, Sheffield, S3 7RH, England, UK.
4 Department of Physics and Astronomy,
California State University Northridge, 18111
Nordhoff Street, Northridge, CA 91330, USA.