Preliminary three-dimensional analysis of the heliospheric response to the 28 October 2003 CME using SMEI white-light observations

The Solar Mass Ejection Imager (SMEI) has recorded the inner heliospheric response in white-light Thomson scattering to the 28 October 2003 coronal mass ejection (CME). This preliminary report shows the evolution of this particular event in SMEI observations, as we track it from a first measurement at approximately 20 degrees elongation (angular distance) from the solar disk until it fades in the antisolar hemisphere in the SMEI 180 degrees field of view. The large angle and spectrometric coronagraph (LASCO) images show a CME and an underlying bright ejection of coronal material that is associated with an erupting prominence. Both of these are seen by SMEI in the interplanetary medium. We employ a three-dimensional (3-D) reconstruction technique that derives its perspective views from outward flowing solar wind to reveal the shape and extent of the CME. This is accomplished by iteratively fitting the parameters of a kinematic solar wind density model to both SMEI white-light observations and Solar-Terrestrial Environment Laboratory (STELab), interplanetary scintillation (IPS) velocity data. This modeling technique separates the true heliospheric signal in SMEI observations from background noise and reconstructs the 3-D heliospheric structure as a function of time. These reconstructions allow separation of the 28 October CME from other nearby heliospheric structure and a determination of its mass. The present results are the first utilizing this type of 3-D reconstruction with the SMEI data. We determine an excess-over-ambient mass for the southward moving ejecta associated with the prominence material of 7.1x10(16) g and a total mass of 8.9x10(16) g. Preliminary SMEI white-light calibration indicates that the total mass of this CME including possible associated nearby structures may have been as much as similar to 2.0x10(17) g spread over much of the earthward facing hemisphere.