1. Solar MURI, June 2003 H.S. Hudson Tracing SEPs from Earth to Sun H. Hudson

2. Solar MURI, June 2003 H.S. Hudson Connectivity from particles The guiding-center motion of charged particles defines field-line location in a plasma (tiny Larmor radii; weak non- adiabaticity) SEP particles can move relativistically fast, and hence can “freeze” coronal structure to establish a connectivity reference Electrons are always semi-relativistic

3. Solar MURI, June 2003 H.S. Hudson How to use the SEPs We have many SEP events, now with RHESSI identification of solar sources. From each we get some knowledge of the connectivity to a probe in the heliosphere Magnetic models based on PFSS theory are now readily available The heliospheric part of the propagation can be approached now from ballistic or better solar-wind models

4. Solar MURI, June 2003 H.S. Hudson May 1, 1998 modeling Schrijver-Derosa modeling for May 2, 1998

5. Solar MURI, June 2003 H.S. Hudson May 12, 1997 modeling Schrijver-Derosa modeling for May 12, 1997

6. Solar MURI, June 2003 H.S. Hudson Schrijver-Derosa modeling for May 2, 1998 Before…… and after

7. Solar MURI, June 2003 H.S. Hudson Pohjolainen et al., ApJ 556, 421 (2001) SXT after minus before, May 2 1998

8. Solar MURI, June 2003 H.S. Hudson Material from Nitta et al. poster This is the first work following the ideas outlined We will present further developments of it at the SHINE, ACERHESSIWind, and AGU meetings

9. Solar MURI, June 2003 H.S. Hudson Finding the open fields

10. Solar MURI, June 2003 H.S. Hudson

11. Solar MURI, June 2003 H.S. Hudson A PFSS Horror Story

12. Solar MURI, June 2003 H.S. Hudson Which Parker spiral? Need to integrate the streamline of the SW flow to find a source-surface footpoint Zeroth approximation with constant speed First approximation via history of SW at probe MHD simulation