Alfvén Waves in the Lower Solar Atmosphere
David B. Jess,1,2*
Mihalis Mathioudakis,1
Robert Erdélyi,3
Philip J. Crockett,1
Francis P. Keenan,1
Damian J. Christian4
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.
2 Solar Physics Laboratory, NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771, USA.
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.
* To whom correspondence should be addressed. E-mail: d.jess{at}qub.ac.uk
