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Comparing Burst Events in Solar Wind and Magnetosphere: Evidence of Heavy Ion Enrichment?

This study examines burst events in the solar wind and magnetosphere, specifically looking at the excess counts of heavy ions beyond the 4He mass range. The results suggest the possibility of a magnetosphere-related acceleration process. The analysis also reveals reduced counts above 80 keV and differences in the H/He ratio between the bursts and the solar wind events.

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Comparing Burst Events in Solar Wind and Magnetosphere: Evidence of Heavy Ion Enrichment?

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  1. SIT-B 40-160 keV • STB CIR events #17,19,20,22 are from period Dec 2007-Feb 2008 (Bucik et al., AnGeo, 2009) • these two bursts periods show an excess in number of counts beyond 4He mass range compared to the CIR events • the excess appears to be a bit larger in the magnetosphere (Feb 7-8) than in the solar wind (Mar 6-7) • is this a special ‘magnetosphere-related acceleration’ on solar wind which leads to the heavy ion enrichment ? • or other than solar wind population is accelerated ?

  2. SIT-B 80-160 keV • these additional counts during the bursts events are considerably reduced above 80 keV! • notice that in CIR histograms species like C, N, O and NeS are not resolved in this energy • range (or linear scale effect?)

  3. Fig.6 in Opitz et al., JGR, 2014; but G.M. Mason reports in the Aug 13, 2014 e-mail a contamination below 80 keV/n for NeS and Fe boxes.

  4. But these burst almost disappears above 80 keV !

  5. gray – counts from both bursts periods; red • – Dec 9 2007 CIR • count excess in 6-12 & 12-20 amu in slide 1 is • due to counts in 40-80 keV/n range; in CIRs there • are many counts in range 60-160 keV/n which masks • this excess in histograms on slide 1 • the shape of the 1st excess (6-12 amu) is due to • energy threshold and contains likely 4He ions • the 2nd excess (12-20 amu) should be due 16O • there is also small 3rdpeak due to NeS ions • since these bursts are low-energy phenomena • we luckily see O and NeS peaks! Therefore the • claiming in Opitz paper that enhancements in bursts • are seen in C-O range was correct. • for 40-80 keV/n the CIR and bursts histograms are • quite similar - implying common seed population • (solar wind)? • at higher energies (see last histogram which is • almost above the threshold energy for hydrogen ) • the H/He ratio in bursts is much different than in • the CIR – implying different acceleration processes ?

  6. previous CIR histograms in log scale 12C 16O 20Ne-32S no ‘so’ obvious peaks?

  7. BACKGROUND • ~20 min periodic bckg. feature, where: • 80-160 keV/n 4He counts shifted to higher amu (to C-O range) & • at higher energies (see 320-640 keV/n) when H counts start to appear, their counts also shifted to higher amu (like 3He) • such bckg. is not visible • above 20 amu and for 40-80 • keV/n – but not sure because counts are low (next slide checks this for a stronger event)

  8. now there are twoperiods • in the background • also this stronger event • shows that NeS, Fe & 40-80 • keV/n are not much affected by • this bckg.

  9. SIT-B bursts on top of CIR event 40-57 57-80 80-113 113-160 etc. 160-226 226-320 320-453 453-640 640-905 • why these bursts coincide with the periodic bckg. increases? But they are not bckg., • otherwise they appear always and it’s not the case! Would we see these bursts if SIT-B is • working without these periodic failures?

  10. … back to the G. Mason ‘s report on contamination < 80 keV/n • in this event, counts in gray area • (40-57 keV) behave differently than rest • energy ranges (especially at ~20-40 amu) • Fe peak is not well separated at • 40-57 but at 57-80 keV/n is separated • well

  11. 101-110 keV SEPT ions STEREO-A sunward pointing sensor anti-sunward pointing pattern similar to STB STEREO-B • the bursts pattern on STA until ~300Re (20 Jan) is similar to STB

  12. #1 #2 #3 #4 sunward pointing sensor anti-sunward pointing STA far (300 Re) from the bow shock ? STB almost at the bow-shock • STB shows more isotropic pattern while STA shows strong anisotropy spikes • in anti-sunward direction; strong simultaneous spikes #1,2,3,4 arrive from anti-sunward direction on STA but from sunward (or are more isotropic) on STB – placing their origin at the bow shock?

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