A New Method to Estimate Halo CME Mass Using Synthetic CMEs Based on a Full Ice Cream Cone Model

• Published in: The Astrophysical journal Vol. 906; no. 1; pp. 46 - 53
• Main Authors: Na, Hyeonock, Moon, Yong-Jae, Lee, Jin-Yi, Cho, Il-Hyun
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.01.2021; IOP Publishing
• Subjects: Astrophysics; Conversion; Coronal mass ejection; Dairy products; Density; Ice cream; Power law; Solar corona; Solar coronal mass ejections
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abc690

In this study, we suggest a new method to estimate the mass of a halo coronal mass ejection (CME) using synthetic CMEs. For this, we generate synthetic CMEs based on two assumptions: (1) the CME structure is a full ice cream cone, and (2) the CME electron number density follows a power-law distribution ( cme = 0r−n). The power-law exponent n is obtained by minimizing the rms error between the electron number density distributions of an observed CME and the corresponding synthetic CME at a position angle of the CME leading edge. By applying this methodology to 56 halo CMEs, we estimate two kinds of synthetic CME masses. One is a synthetic CME mass that considers only the observed CME region (Mcme1), the other is a synthetic CME mass that includes both the observed CME region and the occulted area (Mcme2). From these two cases, we derive conversion factors that are the ratio of a synthetic CME mass to an observed CME mass. The conversion factor for Mcme1 ranges from 1.4 to 3.0 and its average is 2.0. For Mcme2, the factor ranges from 1.8 to 5.0 with an average of 3.0. These results imply that the observed halo CME mass can be underestimated by about 2 times when we consider the observed CME region, and about 3 times when we consider the region including the occulted area. Interestingly these conversion factors have a very strong negative correlation with angular widths of halo CMEs.