根據近期的研究，日冕拋射物質(CMEs)可以被分為兩種類別：高速與低速CMEs。這兩種不同的CMEs有可能是因為不一樣的磁場結構所形成的。研究中也指出兩種CMEs在速度與加速度的特性上有許多的不同。為了得到更多有關於CMEs的資訊，我們利用LASCO CME catalogue 上所取得的資料，在1996年至2004年九月中，所發生的7268個CME事件，做速度、加速度以及緯度上的分析，並觀察其與太陽活動週期地變化。CMEs的平均速度在極大期大約為極小期的兩倍，這是因為高速與低速CMEs在兩個時期中，所佔的比例不同所造成的。而兩種CMEs分別可以的到一個很好的高斯趨近曲線。在緯度的分布上，高速與低速CMEs也有不一樣的特性。高速CMEs只會出現在靠近赤道附近的區域，但低速的出現位置則遍布各地。根據我們的統計，我們相信低速CMEs是符合質量負載模型，而高速則否。 In recently study, it was found that there are two different kinds of coronal mass ejections (CMEs), fast- and slow-moving CMEs, which could be derived form different magnetic structures. It has also been found that these two kinds of CMEs have many distinct characteristics in velocity and acceleration at 2-30 R?. In order to obtain more information about the physical nature of there differences, we have made use of the data provided in the LASCO CME catalogue for the time between 1996 and 2004. We study the statistics of 7268 CMEs velocity, acceleration and the latitude distribution between solar minimum and solar maximum of solar cycle 23. The average CME velocity increases by about a factor of two from solar minimum to maximum. This is due to the changing ratio of the fast- and slow-moving CMEs. It is interesting to find that the velocity distributions of both types of CMEs can be well fitted by the log-normal distribution. We has also found that the fast CMEs tend to occur near the equatorial and low-latitudinal region. Finally, morphological study indicates that the slow CMEs can be best explained by the mass-loading model.
