HR: 11:45h
AN: SH12A-06    [Abstracts]
TI: Using Frontside Halo CMEs and On-Axis Magnetic Flux Ropes to Study CME Structure
AU: * Webb, D F
EM: david.webb@hanscom.af.mil
AF: ISR, Boston College, 140 Commonwealth Ave., Chestnut Hill, MA 02467-3862 United States
AU: Richardson, I G
EM: richardson@lheavx.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Code 661 NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Lepping, R P
EM: Ronald.P.Lepping@nasa.gov
AF: NASA Goddard Space Flight Center, Code 612 NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AB: Data have now been obtained over nearly the entire current solar cycle on both the solar and interplanetary characteristics of coronal mass ejections (CMEs), providing an unprecedented opportunity to understand the structure and development of CMEs. We are studying a set of LASCO frontside full halo (FFH) CMEs associated with magnetic clouds observed at the Wind and ACE spacecraft. Observations of frontside halo CMEs are important because their source regions are well observed near solar disc center, and near-Earth spacecraft may sample the interior structure of the CMEs near their axes. In particular, for this group of events, we require that the magnetic clouds be associated with FFH CMEs, and that the Wind MFI magnetic field data within these clouds can be well-modeled by flux ropes with small impact parameters (i.e., the spacecraft is near the flux rope axis). Previously we had found that most of these clouds drove IP shocks, were decelerating and expanding, had polar rotations in their magnetic fields, and helicities in agreement with the solar hemispherical "rule". Most of the halo CMEs in our sample have associated erupting filaments and dimming regions. The focus here is on the relationship between characteristics of the clouds and the structure of CMEs observed near the Sun, in particular the frequency and location of any cool and/or dense plasma which may signify solar filament material that forms the core of the classic "3-part" structure of CMEs. Most of the events had enhanced He and proton densities toward the rear of or trailing the cloud boundary, suggestive of cool solar material. We will present the results of reexamination of the ICME signatures in these events, including both ACE and Wind composition parameters, with the goal of comparing them with eruptive flare models and reconnection.
DE: 2101 Coronal mass ejections (7513)
DE: 2111 Ejecta, driver gases, and magnetic clouds
DE: 2788 Magnetic storms and substorms (7954)
DE: 7531 Prominence eruptions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005