Comparison of Accelerated Particle Populations at 1 AU and at the Sun

ROSES ID: NNH06ZDA001N      Selection Year: 2007      

Program Element: Focused Science Topic

Principal Investigator: Gerald H. Share

Affiliation(s): Naval Research Laboratory

Project Member(s):
Tylka, Allan J Collaborator NASA Goddard Space Flight Center
Murphy, Ronald J Co-I Naval Research Laboratory
Ryan, James Michael Co-I University of New Hampshire

Summary:

We propose to study the flare-accelerated particle population at the Sun using gamma-ray observations from RHESSI, Yohkoh, CGRO, and SMM. These can be compared to particle-acceleration models and to particle measurements in space and at Earth. This is a key element in determining the contribution of flare-accelerated particles to large gradual SEP events, a goal of the LWS-TR&T in preparing for the Sentinels Mission. As an example of this study we discuss a recent RHESSI analysis of the 2005 January 20 event that revealed two distinct accelerated-particle components at the Sun: 1) an 'impulsive' release lasting ~10 minutes with a power-law index of ~3 observed in a compact region on the Sun and 2) an associated release of much higher energy particles with index <2.3 interacting at the Sun for about two hours. The spectrum of the latter component is consistent with that measured in space. A similar study can be performed in any of over fifty jointly observed gamma-ray flares and SEP events. We suggest that emphasis be placed on the most energetic of these events, those that produce Ground Level Events (GLE).

Publications:

Performance Year	Reference	Investigation Type	Actions
1	Silva, A.V. R., Share, G.H., Murphy, R.J., Costa, J.F.R., Gi...	not set

Presentations:

Performance Year	Reference	Actions
1	Share, Gerald; Murphy, Ronald; (2010), Properties of acc...
1	Murphy, Ronald; Share, G.; Kozlovsky, B.; (2010), Prope...

---

Export to PDF