1 / 11

Multipoint Observations of 3 He-rich SEP Events Since the Launch of STEREO

Multipoint Observations of 3 He-rich SEP Events Since the Launch of STEREO. M.E. Wiedenbeck, JPL/Caltech Thanks to: the ACE/ULEIS &SIS Teams and the STEREO/LET, SIT, & SEPT Teams. Longitudinal Spread of SEPs from 3 He-rich Events

rasha
Download Presentation

Multipoint Observations of 3 He-rich SEP Events Since the Launch of STEREO

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Multipoint Observations of 3He-rich SEP Events Since the Launch of STEREO M.E. Wiedenbeck, JPL/Caltech Thanks to: the ACE/ULEIS &SIS Teams and the STEREO/LET, SIT, & SEPT Teams ACE/SOHO/STEREO/Wind Workshop

  2. Longitudinal Spread of SEPs from 3He-rich Events • single spacecraft studies looked at longitudinal difference between point of SEP observation and site of the flare from which the particles were thought to have been released • complicated by the fact that 3He-rich events are often associated with small x-ray flares, so making the association is sometimes difficult • one of the goals of STEREO is to investigate the characteristics of individual SEP events from multiple points of observation Number of Events Reames 1999 2σ ~ 40° Longitude ACE/SOHO/STEREO/Wind Workshop

  3. Fraction of Time with 3He Present Near 1 AU – Solar Cycle Variation • the first several years of the STEREO mission have characterized by very low solar activity • the number of 3He-rich events available for study has been small, but the chance of confusing different events is significantly reduced • 3He-rich SEP activity has sharply increased in the past 6 months STEREO Launch ACE ULEIS & SIS points: individual Bartels rotation curve: 7-rotation averages ACE/SOHO/STEREO/Wind Workshop

  4. 3He Observed with ACE: Solar Minimum--Solar Maximum Comparison • at solar maximum there are lots of 3He-rich events • at solar minimum 3He-rich events are rare—provides a better opportunity to correlate events between different spacecraft without (much) confusion Solar Minimum Solar Maximum small 3He-rich event ACE/SOHO/STEREO/Wind Workshop

  5. 3He rich Events at ACE, STEREO-Ahead, and STEREO-Behind ticks indicate days with 3He-rich SEPs present AHEAD ±20° ACE • Data sources: • STEREO-A & -B: LET, 2.3-3.8 MeV/nuc • ACE: ULEIS, 0.2-1 MeV/nuc BEHIND ACE/SOHO/STEREO/Wind Workshop

  6. 3He rich Events at ACE, STEREO-Ahead, and STEREO-Behind • an event observed on both STEREO spacecraft and on ACE AHEAD ±20° ACE BEHIND ACE/SOHO/STEREO/Wind Workshop

  7. Event Observed over a Wide Range of Heliographic Longitudes • 3-4 Nov 2008 event • the STEREOs were located ±41° from ACE • electrons were observed at all three spacecraft using STEREO/SEPT and ACE/EPAM • 3He and heavy ions with enhanced Fe/O were observed at STEREO-B and ACE • the lack of an ion detection at STEREO-A might be due to sensitivity limitations • results discussed in Wiedenbeck et al. 2010, SW12 Proceedings ACE/SOHO/STEREO/Wind Workshop

  8. 3He rich Events at ACE, STEREO-Ahead, and STEREO-Behind • events in the first quarter of 2010 AHEAD ±20° ACE BEHIND ACE/SOHO/STEREO/Wind Workshop

  9. Increased Rate of 3He-rich Events in Early 2010 • see numerous events, some of which overlap in time • In some cases there are approximate time coincidences (e.g., Feb 13-15), but often there are not • these 3He-rich events have very low intensity compared to some events observed near solar maximum; with larger events, establishing that different spacecraft are observing the same event should be easier ACE/SOHO/STEREO/Wind Workshop

  10. Improving Reliability of Event Associations between Different Spacecraft • A variety of event characteristics can be compared to improve confidence in associations between events detected at different spacecraft: • timing of onset • timing of release from the Sun (onset time corrected for transit time based on velocity dispersion) • fluence • details of time-intensity profile • energy spectra • anisotropy • associated impulsive electron events • ion composition (3He/4He, Fe/O, etc.) • Useful comparisons with solar context: • jets associated with the flare event • longitudinal spread of open field from active region from PFSS model • Larger events are needed to take advantage of many of these comparisons. ACE/SOHO/STEREO/Wind Workshop

  11. STEREO/LET Observations of • 3He-rich SEPs at Solar Minimum • search for events in low energy (2.3-3.8 MeV/nuc) interval to improve ratio of He signal to background from ACRs & CIRs. • events are typically very small • to confirm event identification, look for 1) 3He spectrum that falls with increasing energy, 2) anisotropy, 3) velocity dispersion, and/or 4) coincident electron event to Sun STEREO-A SEPT electron measurements ACE/SOHO/STEREO/Wind Workshop

More Related