National Aeronautics and Space Administration

Living With A Star

Targeted Research and Technology

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


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).


Performance YearReferenceInvestigation TypeActions
1Silva, A.V. R., Share, G.H., Murphy, R.J., Costa, J.F.R., Gi...
not set


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

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