Suzaku detection of enigmatic geocoronal solar wind charge exchange event associated with coronal mass ejection

Daiki Ishi, Kumi Ishikawa, Masaki Numazawa, Yoshizumi Miyoshi, Naoki Terada, Kazuhisa Mitsuda, Takaya Ohashi, Yuichiro Ezoe

Research output: Contribution to journalArticle

Abstract

Suzaku detected an enhancement of the soft X-ray background associated with solar eruptions on 2013 April 14-15. The solar eruptions were accompanied by an M6.5 solar flare and a coronal mass ejection with magnetic flux ropes. The enhanced soft X-ray background showed a slight variation over half a day and then a clear one in a few hours. The former spectrum was composed of oxygen emission lines, while the later one was characterized by a series of emission lines from highly ionized carbon to silicon. The soft X-ray enhancement originated from geocoronal solar wind charge exchange. However, there appeared to be no significant time correlation with the solar wind proton flux measured by the ACE and WIND satellites. From other solar wind signatures, we considered that an interplanetary shock associated with the coronal mass ejection and a turbulent sheath immediately behind the shock compressed the ambient solar wind ions and then resulted in the soft X-ray enhancement. Furthermore, the enriched emission lines were presumed to be due to an unusual set of ion abundances and ionization states within the coronal mass ejection. We found a better time correlation with the solar wind alpha flux rather than the solar wind proton flux. Our results suggest that the solar wind proton flux is not always a good indicator of geocoronal solar wind charge exchange, especially associated with coronal mass ejections. Instead, the solar wind alpha flux should be investigated when such a soft X-ray enhancement is detected in astronomical observations.

Original languageEnglish
Article number23
JournalPublications of the Astronomical Society of Japan
Volume71
Issue number1
DOIs
Publication statusPublished - 2019 Jan 1

Keywords

  • Earth
  • Sun: Coronal mass ejections (CMEs)
  • Sun: Flares
  • Sun: Solar-terrestrial relations
  • X-rays: Diffuse background

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Suzaku detection of enigmatic geocoronal solar wind charge exchange event associated with coronal mass ejection'. Together they form a unique fingerprint.

  • Cite this