Origin of Neutral Particles and Ions with Low Charges States in the Heliosphere

Despite the high coronal temperature which exceeds 1 MK, emission lines of neutral atoms have been observed spectroscopically. In-situ observations occasionally show very low charge states in Interpanetary Coronal Mass Ejections (ICMEs), hinting at the possibility of a small fraction of neutral material in what is presumed to be prominence material which was ejected together with the CME. In addition, STEREO/LET has reported one observation of neutral energetic particles. Together, these observations hint at the possibility of using neutral particles as a tracer for coronal processes. Farther out, the interaction of the charged solar wind with interplanetary dust particles results in a small population of neutral particles which are quickly ionized and observed as inner-source pickup ions. They are complemented by neutral atoms which enter the heliosphere from the surrounding very local interstellar medium.

In this talk we will summarize observations of ions with low charge states and investigate their implications for neutral particles in the inner heliosphere.