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Science 22 April 2005:
Vol. 308. no. 5721, pp. 519 - 523
DOI: 10.1126/science.1109447
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Research Articles

Solar Wind Origin in Coronal Funnels

Chuan-Yi Tu,1,3* Cheng Zhou,2 Eckart Marsch,3 Li-Dong Xia,4 Liang Zhao,1 Jing-Xiu Wang,5 Klaus Wilhelm3

The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by various ions with the force-free magnetic field as extrapolated from photospheric magnetograms to different altitudes. Specifically, we find that Ne7+ ions mostly radiate around 20 megameters, where they have outflow speeds of about 10 kilometers per second, whereas C3+ ions with no average flow speed mainly radiate around 5 megameters. Based on these results, a model for understanding the solar wind origin is suggested.

1 Department of Geophysics, Peking University, Beijing 100871, China.
2 Department of Atmospheric Sciences, Peking University, Beijing 100871, China.
3 Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany.
4 School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
5 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China.

* To whom correspondence should be addressed. E-mail: cytu{at}public3.bta.net.cn

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Continuous Plasma Outflows from the Edge of a Solar Active Region as a Possible Source of Solar Wind.
T. Sakao, R. Kano, N. Narukage, J. Kotoku, T. Bando, E. E. DeLuca, L. L. Lundquist, S. Tsuneta, L. K. Harra, Y. Katsukawa, et al. (2007)
Science 318, 1585-1588
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