Progenitors to Geoeffective Coronal Mass Ejections: Filaments and Sigmoids

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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
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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

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Proposed Work
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?

• Investigate systematic differences in magnetic
  clouds resulting from eruption of filaments and
  sigmoids, e.g.,
• Temperature depression
• Increase in magnetic field strength and plasma ß
• 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

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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

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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 a/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 Inconclusive Inconclusive
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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