Solar Physics

, Volume 279, Issue 2, pp 517–535

Observational Tracking of the 2D Structure of Coronal Mass Ejections Between the Sun and 1 AU

  • N. P. Savani
  • J. A. Davies
  • C. J. Davis
  • D. Shiota
  • A. P. Rouillard
  • M. J. Owens
  • K. Kusano
  • V. Bothmer
  • S. P. Bamford
  • C. J. Lintott
  • A. Smith
Article

DOI: 10.1007/s11207-012-0041-6

Cite this article as:
Savani, N.P., Davies, J.A., Davis, C.J. et al. Sol Phys (2012) 279: 517. doi:10.1007/s11207-012-0041-6

Abstract

The Solar TErrestrial RElations Observatory (STEREO) provides high cadence and high resolution images of the structure and morphology of coronal mass ejections (CMEs) in the inner heliosphere. CME directions and propagation speeds have often been estimated through the use of time-elongation maps obtained from the STEREO Heliospheric Imager (HI) data. Many of these CMEs have been identified by citizen scientists working within the SolarStormWatch project (www.solarstormwatch.com) as they work towards providing robust real-time identification of Earth-directed CMEs. The wide field of view of HI allows scientists to directly observe the two-dimensional (2D) structures, while the relative simplicity of time-elongation analysis means that it can be easily applied to many such events, thereby enabling a much deeper understanding of how CMEs evolve between the Sun and the Earth. For events with certain orientations, both the rear and front edges of the CME can be monitored at varying heliocentric distances (R) between the Sun and 1 AU. Here we take four example events with measurable position angle widths and identified by the citizen scientists. These events were chosen for the clarity of their structure within the HI cameras and their long track lengths in the time-elongation maps. We show a linear dependency with R for the growth of the radial width (W) and the 2D aspect ratio (χ) of these CMEs, which are measured out to ≈ 0.7 AU. We estimated the radial width from a linear best fit for the average of the four CMEs. We obtained the relationships W=0.14R+0.04 for the width and χ=2.5R+0.86 for the aspect ratio (W and R in units of AU).

Keywords

Coronal mass ejections (CMEs) Heliosphere Solar-terrestrial relations Solar wind 

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • N. P. Savani
    • 1
    • 10
  • J. A. Davies
    • 2
  • C. J. Davis
    • 2
    • 5
  • D. Shiota
    • 3
  • A. P. Rouillard
    • 10
    • 4
  • M. J. Owens
    • 11
    • 5
  • K. Kusano
    • 12
    • 6
  • V. Bothmer
    • 7
  • S. P. Bamford
    • 8
  • C. J. Lintott
    • 9
  • A. Smith
    • 9
  1. 1.University Corporation for Atmospheric Physics (UCAR)BoulderUSA
  2. 2.RAL SpaceSTFC Rutherford Appleton LaboratoryHarwell OxfordUK
  3. 3.Computational Astrophysics LaboratoryAdvanced Science Institute, RIKENWako, SaitamaJapan
  4. 4.College of ScienceGeorge Mason UniversityFairfaxUSA
  5. 5.Space Environment Physic GroupUniversity of ReadingReadingUK
  6. 6.Solar-Terrestrial Environment LaboratoryNagoya UniversityNagoyaJapan
  7. 7.Institut für AstrophysikGöttingen UniversityGöttingenGermany
  8. 8.Centre for Astronomy and Particle TheoryUniversity of NottinghamNottinghamUK
  9. 9.AstrophysicsUniversity of OxfordOxfordUK
  10. 10.Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltUSA
  11. 11.The Blackett LaboratoryImperial College LondonLondonUK
  12. 12.Japan Agency for Marine-Earth Science and TechnologyYokohama, KanagawaJapan

Personalised recommendations