1. The Sources of Solar Hazards in Interplanetary Space Leonard Strachan & Jun Lin (Harvard – Smithsonian Center for Astrophysics) Paper [72.05] “Contributions from Ultraviolet Spectroscopy to the Prediction of High-energy Proton Hazards from CME Shocks” – J. Lin, J. C. Raymond, S. R. Cranmer, and J. L. Kohl AAS 204 th Meeting May 31, 2004 Denver, Colorado

5. The Sources of Solar Hazards in Space  Introduction and Overview  NASA has announced its new vision of human interplanetary space exploration  To accomplish this goal, astronauts will need to contend with solar particle radiation that may be hazardous to themselves and their equipment  In order to warn astronauts of impending risks, we need to understand HOW and WHERE these particles are produced

6. The Sources of Solar Hazards in Space  Anatomy of the Flare/CME System:  Flare/CME initiation  Rising CME bubble  Current sheet between the flare and CME  We believe there are two regions where the particle radiation is produced: 1. Electrified “Current Sheet” 2. Shock wave in front of the Coronal Mass Ejection CME

7. Sun CME The Sources of Solar Hazards in Space  Lin & Forbes model predicts a hot current sheet where energetic particles are produced  As predicted, UVCS observes a 6 million degree Celsius current sheet thus validating the model  The Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft

8. The Sources of Solar Hazards in Space  Theories predict shock- heated gas and energetic particle production near the CME front Tsurutani, et al. (2003)  As predicted, UVCS measured a 30 million degree Celsius gas behind the CME shock, indicating the production of energetic particles Hot gas

9. The Sources of Solar Hazards in Space  UVCS observations determine the physical properties at the sites where energetic particles are produced.  shock temperatures  shock speed  precise location of source regions  shock strength  magnetic field strength  UVCS provides quantitative information on:

11. The Sources of Solar Hazards in Space  Role of the current sheet:  Converts magnetic energy to heating and kinetic energy  Plasma is heated to 6-10 Million degrees Celsius  Charged particles are accelerated by an electric field across the current sheet  Accelerated particles escape when they reach open magnetic field lines

12. The Sources of Solar Hazards in Space  A first step: Ongoing ultraviolet observations along with advanced theoretical models provide an improved understanding of the onset of solar energetic particle events and their severity.  A future monitoring and predictive system will benefit from the present work which aims to understand the physical conditions at sites where solar energetic particles are produced. In Summary …