Parker Solar Probe Observations of Alfvénic Waves and Ion-cyclotron Waves in a Small-scale Flux Rope
- 1Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, People’s Republic of China
- 2School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, People’s Republic of China
- 3Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- 4RAL Space, STFC, Oxfordshire OX11 0QX, UK
- 5Department of Space Science, The University of Alabama in Huntsville, Huntsville, AL 35805, USA
- 6Center for Space Plasma and Aeronomic Research (CSPAR), The University of Alabama in Huntsville, Huntsville, AL 35805, USA
- 7Smithsonian Astrophysical Observatory, Cambridge, MA 02138, USA
- 8Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA
- 9Physics Department, University of California, Berkeley, CA 94720-7300, USA
- 10The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
Magnetic flux ropes can play important roles in transferring the mass, momentum, and energy in the interplanetary environment and in affecting space weather. Small-scale flux ropes (SFRs) are common in the interplanetary environment. However, SFRs with medium and high Alfvénicity are generally discarded in previous identification procedures. Using Parker Solar Probe measurements, we identify an SFR event with medium Alfvénicity in the inner heliosphere (at ~ 0.2 au). Based on high correlations between the magnetic field and velocity fluctuations, we show Alfvénic waves arising inside such SFR. We also show occurrence of quasi-monochromatic electromagnetic waves at the leading and trailing edges of this SFR. These waves are well explained by the outward-propagating ion-cyclotron waves, which have wave frequencies ~ 0.03 - 0.3 Hz and wavelengths ~ 60 - 2000 km in the plasma frame. Furthermore, we show that the power spectral density of the magnetic field in SFR middle region follows the power-law distribution, where the spectral index changes from -1.5 (f <~ 1 Hz) to -3.3 (f >~ 1 Hz). These findings would motivate developing an automated program to identify SFRs with medium and high Alfvénicity from Alfvénic waves structures.
How to cite: Shi, C., Zhao, J., Huang, J., Wang, T., Wu, D., Chen, Y., Hu, Q., Kasper, J. C., and Bale, S. D.: Parker Solar Probe Observations of Alfvénic Waves and Ion-cyclotron Waves in a Small-scale Flux Rope, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14934, https://doi.org/10.5194/egusphere-egu21-14934, 2021.
