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A Proton-Cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar WindWe use audification of 0.092 seconds cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes greater than 0.1 nanoteslas near the ion gyrofrequency (approximately 0.1 hertz) with duration longer than 1 hour during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.
Document ID
20160007473
Document Type
Reprint (Version printed in journal)
Authors
Wicks, R. T. (University Coll. London, United Kingdom)
Alexander, R. L. (Michigan Univ. Ann Arbor, MI, United States)
Stevens, M. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Wilson, L. B., III (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Moya, P. S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Vinas, A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jian, L. K. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Roberts, D. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
O’Modhrain, S. (Michigan Univ. Ann Arbor, MI, United States)
Gilbert, J. A. (Michigan Univ. Ann Arbor, MI, United States)
Zurbuchen, T. H. (Michigan Univ. Ann Arbor, MI, United States)
Date Acquired
June 13, 2016
Publication Date
February 23, 2016
Publication Information
Publication: The Astrophysical Journal
Volume: 819
Issue: 1 Witer
Subject Category
Solar Physics
Acoustics
Report/Patent Number
GSFC-E-DAA-TN30960
Funding Number(s)
CONTRACT_GRANT: NNX13AI65G
Distribution Limits
Public
Copyright
Other
Keywords
instabilities - plasmas
waves
solar wind