Cold prominence materials detected within magnetic clouds during 1998–2007

Context. Coronal mass ejections (CMEs) are intense solar explosive eruptions, and they are frequently correlated with prominence eruptions. Previous observations show that about 70% of CMEs are associated with prominence eruptions. However, there are only a handful of reported observations of prominence plasma materials within interplanetary CMEs (ICMEs), which are the interplanetary manifestations of CMEs. Moreover, approximately 4% of ICMEs exhibit the presence of prominence materials, and approximately 12% of magnetic clouds (MCs) contain prominence materials. Aims. We aim to comprehensively search for cold prominence materials in MCs observed by the Advanced Composition Explorer (ACE) spacecraft during 1998–2007. Methods. Using the criteria of unusual O5+ and (or) Fe6+ abundances, we examined 76 MCs observed by ACE during 1998–2007 to search for cold prominence materials. Results. Our results revealed that out of the 76 MCs, 27 (36%) events contained prominence material regions with low-charge-state signatures. Conclusions. Although the fraction is still lower than the approximately 70% of CMEs associated with prominence eruptions, it is much higher than 12%. The unusual O5+ and (or) Fe6+ abundances may be simple and reliable criteria to investigate prominence materials in the interplanetary medium