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Title: Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?

Abstract

Previous studies revealed that electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency exist widely in the solar wind, and the majority of ECWs are left-handed (LH) polarized waves. Using the magnetic field data from the STEREO mission, this Letter carries out a survey of ECWs over a long period of 7 years and calculates the occurrence rates of ECWs with different polarization senses. Results show that the occurrence rate is nearly a constant for the ECWs with right-handed polarization, but it varies significantly for the ECWs with LH polarization. Further investigation of plasma conditions reveals that the LH ECWs take place preferentially in a plasma characterized by higher temperature, lower density, and larger velocity. Some considerable correlations between the occurrence rate of LH ECWs and the properties of ambient plasmas are discussed. The present research may provide evidence for the effect of alpha particles on the generation of ECWs.

Authors:
;  [1];  [2];  [3];  [4]
  1. Institute of Space Physics, Luoyang Normal University, Luoyang (China)
  2. Purple Mountain Observatory, CAS, Nanjing (China)
  3. Institute of Space Science, National Central University, Chungli, Taiwan (China)
  4. CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing (China)
Publication Date:
OSTI Identifier:
22654385
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 847; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALPHA PARTICLES; CORRELATIONS; CYCLOTRON FREQUENCY; CYCLOTRON RADIATION; DENSITY; INSTABILITY; MAGNETIC FIELDS; PLASMA; POLARIZATION; PROTONS; SOLAR WIND; TIME DEPENDENCE; VELOCITY

Citation Formats

Zhao, G. Q., Feng, H. Q., Wu, D. J., Chu, Y. H., and Huang, J. Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA88B3.
Zhao, G. Q., Feng, H. Q., Wu, D. J., Chu, Y. H., & Huang, J. Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?. United States. doi:10.3847/2041-8213/AA88B3.
Zhao, G. Q., Feng, H. Q., Wu, D. J., Chu, Y. H., and Huang, J. Wed . "Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?". United States. doi:10.3847/2041-8213/AA88B3.
@article{osti_22654385,
title = {Time-dependent Occurrence Rate of Electromagnetic Cyclotron Waves in the Solar Wind: Evidence for the Effect of Alpha Particles?},
author = {Zhao, G. Q. and Feng, H. Q. and Wu, D. J. and Chu, Y. H. and Huang, J.},
abstractNote = {Previous studies revealed that electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency exist widely in the solar wind, and the majority of ECWs are left-handed (LH) polarized waves. Using the magnetic field data from the STEREO mission, this Letter carries out a survey of ECWs over a long period of 7 years and calculates the occurrence rates of ECWs with different polarization senses. Results show that the occurrence rate is nearly a constant for the ECWs with right-handed polarization, but it varies significantly for the ECWs with LH polarization. Further investigation of plasma conditions reveals that the LH ECWs take place preferentially in a plasma characterized by higher temperature, lower density, and larger velocity. Some considerable correlations between the occurrence rate of LH ECWs and the properties of ambient plasmas are discussed. The present research may provide evidence for the effect of alpha particles on the generation of ECWs.},
doi = {10.3847/2041-8213/AA88B3},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 847,
place = {United States},
year = {Wed Sep 20 00:00:00 EDT 2017},
month = {Wed Sep 20 00:00:00 EDT 2017}
}