CORONAL MASS EJECTION PROPAGATION AND EXPANSION IN THREE-DIMENSIONAL SPACE IN THE HELIOSPHERE BASED ON STEREO/SECCHI OBSERVATIONS
- Department of Computational and Data Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
We report on several new findings regarding the kinematic and morphological evolution of coronal mass ejections (CMEs) in the inner heliosphere using the unprecedented STEREO/SECCHI observations. The CME tracking is based on the three-dimensional Raytrace model, which is free of the projection effect, resulting in true CME velocities. We also measure the cross section size of the CME and hence its expansion velocity. For the four major CME events investigated, we find that their leading edge (LE) velocity converges from an initial range between 400 km s{sup -1} and 1500 km s{sup -1} at 5-10 R{sub sun} to a narrow range between 500 km s{sup -1} and 750 km s{sup -1} at 50 R{sub sun}. The expansion velocity is also found to converge into a narrow range between 75 km s{sup -1} and 175 km s{sup -1}. Both LE and expansion velocities are nearly constant after 50 R{sub sun}. We further find that the acceleration of CMEs in the inner heliosphere from {approx}10 to 90 R{sub sun} can be described by an exponential function, with an initial value as large as {approx}-80 m s{sup -2} but exponentially decreasing to almost zero (more precisely, less than {+-}5 m s{sup -2} considering the uncertainty of measurements). These results provide important observational constraints on understanding CME dynamics in interplanetary space.
- OSTI ID:
- 21451033
- Journal Information:
- Astrophysical Journal Letters, Vol. 717, Issue 2; Other Information: DOI: 10.1088/2041-8205/717/2/L159; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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