Annales Geophysicae 27, 4097-4104, 2009
in: R. Forsyth, R. Harrison, J. Luhmann, B. Fleck and C. St Cyr (eds.)
Three Eyes on the Sun−Multi−spacecraft studies of the corona and impacts on the heliosphere (STEREO−3/SOHO−22 Workshop)
© Authors 2009
SMEI direct, 3-D-reconstruction sky maps, and volumetric analyses, and their comparison with SOHO and STEREO observations
B.V. Jackson, P.P. Hick, A. Buffington, M.M. Bisi, J.M. Clover
Center for Astrophysics and Space Sciences, Univ. of California San Diego, La Jolla, CA, USA
In this paper we present the results of the analysis of the late January 2007
Coronal Mass Ejection (CME) events recorded by the Solar Mass Ejection Imager
(SMEI), the Solar TErrestrial RElations Observatory (STEREO), and the SOlar and
Heliospheric Observatory (SOHO) spacecraft. This period occurs when the two
STEREO spacecraft views are from close to Earth, and thus the views from both
SMEI and the STEREO outer Heliospheric Imagers (HI-2s) coincide.
Three-dimensional (3-D) analyses derived from SMEI data show many CMEs that
have also been studied by others using short-term image subtractions
(image-differencing techniques). During this interval we map several CME
structures that are observed in both SMEI and the STEREO-A HI instruments.
SMEI brightness analyses provided by short-term image subtractions
(“difference images”) and, alternatively, subtractions of a mean-brightness
fit over a long-time duration, both show the extents of the CMEs travelling
outward above the East limb that erupted from the Sun on 24 and 25 January 2007.
The SMEI 3-D-reconstructions not only enhance distinct features within the CME
events, but also reconcile difference-imaging results with those where a
long-term base has been removed. In the January 2007 example the structure as
mapped by CME difference images traces the sharp intensity gradients at the
front of the CMEs; generally brighter ejected material follows behind the
location of the CME front, but shows poorly in these because of its larger
angular extent. Using the long-duration background removal enables SMEI’s 3-D
analysis to determine a mass for this CME sequence North of the ecliptic.