Volume 442, Number 3, November II 2005
|Page(s)||1087 - 1090|
|Published online||14 October 2005|
Very long period activity at the base of solar wind streams
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland e-mail: [mdp;eos;jgd]@arm.ac.uk
2 Astronomical Institute of the Romanian Academy, 040557 Bucharest 28, Romania
3 Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India e-mail: firstname.lastname@example.org
4 School of Earth and Space Sciences, Univ. of Science and Technology of China, Hefei, Anhui 230026, PR China e-mail: email@example.com
Accepted: 18 July 2005
Using time series data of spectral lines originating from a wide range of temperatures in the solar transition region, above a polar coronal hole, from SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SoHO (Solar and Heliospheric Observatory), we report on the detection of very long (≈170 min) periodic intensity fluctuations, above the limb. Our data also reveal long periodicities (10–90 min), previously observed with other SoHO instruments. With the acoustic cut-off frequency implying a maximum allowable period of ≈90 min, it is unclear whether these intensity fluctuations are due to waves or are the result of a recurrent magnetic reconnection process.
Key words: Sun: solar wind / Sun: transition region / Sun: corona
© ESO, 2005
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