LARGE-AMPLITUDE ALFVEN WAVE IN INTERPLANETARY SPACE: THE WIND SPACECRAFT OBSERVATIONS

Journal Article · Mon Feb 20 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/746/2/147· OSTI ID:22011739

Xin, Wang; Jiansen, He; Chuanyi, Tu; Lei, Zhang ^[1]; Marsch, Eckart ^[2]; Chao, Jih-Kwin ^[3]

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1. School of Earth and Space Sciences, Peking University, Beijing 100871 (China)
2. Max-Planck-Institut fuer Sonnensystemforschung, 37191 Katlenburg-Lindau (Germany)
3. Institute of Space Science, National Central University, Chung-Li 32054, Taiwan (China)

We present, for the first time, measurements of arc-polarized velocity variations together with magnetic field variations associated with a large-amplitude Alfven wave as observed by the Wind satellite. The module of the magnetic field variance is larger than the magnitude of the average magnetic field, indicating the large amplitude of these fluctuations. When converting to the deHoffman-Teller frame, we find that the magnetic field and velocity vector components, in the plane perpendicular to the minimum-variance direction of the magnetic field, are arc-polarized, and their tips almost lie on the same circle. We also find that the normalized cross helicity and Alfven ratio of the wave are both nearly equal to unity, a result which has not been reported in previous studies at 1 AU. It is worthy to stress here that pure Alfven waves can also exist in the solar wind even near the Earth at 1 AU, but not only near 0.3 AU. Further study could be done to help us know more about the properties of pure Alfven wave at 1 AU that could not be figured out easily before because of the contaminations (e.g., Alfven waves propagating in different directions, magnetic structures, and other compressional waves) on previously reported Alfven wave cases.

• OSTI ID: 22011739
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 746; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
HELICITY
INTERPLANETARY SPACE
MAGNETIC FIELDS
POLARIZATION
SOLAR WIND
TIME MEASUREMENT
WAVE PROPAGATION