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

Solar MURI, June 2003H.S. Hudson

Tracing SEPs from Earth to Sun

H. Hudson

Solar MURI, June 2003H.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

Solar MURI, June 2003H.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

Solar MURI, June 2003H.S. Hudson

May 1, 1998 modeling

Schrijver-Derosa modeling for May 2, 1998

Solar MURI, June 2003H.S. Hudson

May 12, 1997 modeling

Schrijver-Derosa modeling for May 12, 1997

Solar MURI, June 2003H.S. Hudson

Schrijver-Derosa modeling for May 2, 1998

Before… … and after

Solar MURI, June 2003H.S. Hudson

Pohjolainen et al., ApJ 556, 421 (2001)

SXT after minus before, May 2 1998

Solar MURI, June 2003H.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

Solar MURI, June 2003H.S. Hudson

Finding the open fields

Solar MURI, June 2003H.S. Hudson

Solar MURI, June 2003H.S. Hudson

A PFSS Horror Story

Solar MURI, June 2003H.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