Radial Evolution of Well-Observed Slow CMEs intheDistance Range 2-30 R ()

• Published in: Solar physics 2009-07, Vol.257 (2), p.351-361
• Main Authors: Shanmugaraju, A, Moon, Y.-J., Vrsnak, Bojan, Vrbanec, Dijana
• Format: Article
• Language: English
• ISSN: 0038-0938
• DOI: 10.1007/s11207-009-9379-9

We performed a detailed analysis of 27 slow coronal mass ejections (CMEs) whose heights were measured in at least 30 coronagraphic images and were characterized by a high quality index (.4). Our primary aim was to study the radial evolution of these CMEs and their properties in the range 2-30 solar radii. The instantaneous speeds of CMEs were calculated by using successive height-time data pairs. The obtained speed-distance profiles [v(R)] are fitted by a power law v = a(R-b)( c ). The power-law indices are found to be in the ranges a=30-386, b=1.95-3.92, and c=0.03-0.79. The power-law exponent c is found to be larger for slower and narrower CMEs. With the exception of two events that had approximately constant velocity, all events were accelerating. The majority of accelerating events shows a v(R) profile very similar to the solar-wind profile deduced by Sheeley et al. (Astrophys. J. 484, 472, 1997). This indicates that the dynamics of most slow CMEs are dominated by the solar wind drag.