Chromospheric Alfvénic Waves Strong Enough to Power the Solar Wind
B. De Pontieu,1*
S. W. McIntosh,2,3
M. Carlsson,4
V. H. Hansteen,4,1
T. D. Tarbell,1
C. J. Schrijver,1
A. M. Title,1
R. A. Shine,1
S. Tsuneta,5
Y. Katsukawa,5
K. Ichimoto,5
Y. Suematsu,5
T. Shimizu,6
S. Nagata7
Alfvén waves have been invoked as a possible mechanism for the heating of the Sun's outer atmosphere, or corona, to millions of degrees and for the acceleration of the solar wind to hundreds of kilometers per second. However, Alfvén waves of sufficient strength have not been unambiguously observed in the solar atmosphere. We used images of high temporal and spatial resolution obtained with the Solar Optical Telescope onboard the Japanese Hinode satellite to reveal that the chromosphere, the region sandwiched between the solar surface and the corona, is permeated by Alfvén waves with strong amplitudes on the order of 10 to 25 kilometers per second and periods of 100 to 500 seconds. Estimates of the energy flux carried by these waves and comparisons with advanced radiative magnetohydrodynamic simulations indicate that such Alfvén waves are energetic enough to accelerate the solar wind and possibly to heat the quiet corona.
1 Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Organization ADBS, Building 252, Palo Alto, CA 94304, USA.
2 Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302, USA.
3 High Altitude Observatory, National Center for Atmospheric Research, Post Office Box 3000, Boulder, CO 80307, USA.
4 Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, 0315 Oslo, Norway.
5 National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japan.
6 Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan.
7 Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471, Japan.
* To whom correspondence should be addressed. E-mail: bdp{at}lmsal.com
