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.