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Progenitors to Geoeffective Coronal Mass Ejections: Filaments and Sigmoids

Progenitors to Geoeffective Coronal Mass Ejections: Filaments and Sigmoids. David McKenzie, Robert Leamon Karen Wilson, Zhona Tang, Anthony Running Wolf. PROM Workshop, September 30, 2003. CMEs: Different sources, different effects?.

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Progenitors to Geoeffective Coronal Mass Ejections: Filaments and Sigmoids

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  1. Progenitors to Geoeffective Coronal Mass Ejections: Filaments and Sigmoids David McKenzie, Robert Leamon Karen Wilson, Zhona Tang, Anthony Running Wolf PROM Workshop, September 30, 2003

  2. CMEs: Different sources, different effects? • Focus on two specific kinds of CME progenitors: erupting filaments and coronal sigmoids • Both have been modeled with flux rope structure • Differences in associated ICMEs (Leamon et al 2002) • Phase of leading field reversal • Hemispheric rule of handedness • Goal: Capitalize on the differences

  3. “If the potential for geoeffectiveness depends on the details of the pre-eruption magnetic structures, can the characteristics of magnetic clouds at 1 au be related statistically to measurements made via remote sensing?” Proposed Work • Investigate systematic differences in magnetic clouds resulting from eruption of filaments and sigmoids, e.g., • Temperature depression • Increase in magnetic field strength and plasma β • Composition (ion charge state distribution) • Test if magnetic field strength can be linked to CME acceleration • Examine correlation between magnetic cloud tilt angle and duration of southward IMF • Explore relationship of progenitor axial field and overlying PFSS field

  4. Baby steps • Assemble list of geomagnetic storms • Cane & Richardson (2003) • Zhang et al (2003) • Leamon et al (2002) • Webb (p.c.), Jones (p.c.) • Collect solar wind data from ACE, Wind • magnetic field strength & direction • proton density • alpha/proton density ratio • temperature • Average conditions within magnetic cloud • Fit flux rope model to in situ data • Associate each magnetic cloud with its progenitor, compare two populations

  5. Preliminary, very preliminary • Choice of sixteen geoeffective magnetic clouds • 9 sigmoids • 7 non-active region filaments • Very small sample: “Lies, damn lies, and sigmoids” density velocity temp α/p ratio Dst (cm-3) (km/s) (kK) Filaments 9.8 ± 1.5 482 ± 26 40.7 ± 5.8 5.6 ± 1 -115 ± 30 Sigmoids 6.6 ± 1.6 492 ± 38 47.7 ± 9.6 6.6 ± 1.5 -144 ± 25 Different Same Inconclusive InconclusiveInconclusive

  6. To do • More events tied to their progenitors and flux rope models • Incorporate photospheric magnetic field measurements • PFSS relationships This work supported by NASA Grant NAG5-13500, Living With a Star Targeted Research & Technology

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