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STE quiet-time observations during solar minimum. Linghua Wang, Robert Lin and Janet Luhmann SSL, UC Berkeley. Outline 1. Superthermal electron tail in the quiet-time solar wind 2. Pick-up ions 3. The ion beam traveling radially towards the Sun ??.
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STE quiet-time observations during solar minimum Linghua Wang, Robert Lin and Janet Luhmann SSL, UC Berkeley
Outline 1. Superthermal electron tail in the quiet-time solar wind 2. Pick-up ions 3. The ion beam traveling radially towards the Sun ??
1. Superthermal electron tail (~2-100 keV) Sun STE D2 D1 2007 May01 D0 1000 0 -1000 A D3 GSE X (RE) Earth T B R 1000 0 -1000 GSE Y (RE) Parker’s spiral B field
10-2 10-4 10-1 10-3 10-5 160 120 80 4 2 0 300 100 50 0 -50 STE D0 STE D2 D2 D1 D0 D3 ΘBΦB |B| PA Flux Flux 19:00 20:00 21:00 22:00 23:00 2007 May 01 (STEREO B )
2007 May01 105 100 10-5 WIND/3DP EESA-L Flux (cm2· s · sr · eV)-1 Flux (cm2· s · sr · eV/nucleon )-1 WIND/3DP EESA-H STE D0 D1D2D3 (STEREO B) + SEPT-E STE (STEREO B) 100 101 102 103 104 105 106 Energy (eV or eV/nucleon)
2007 May01 (STEREO B) 10-2 10-3 10-4 10-5 10-6 10-7 + STE D0 D1D2D3 ~ E-2.13 ~ E-2.07 Flux (cm2· s · sr · eV)-1 SEPT-E ~ E-1.1 103 104 105 106 Energy (eV)
2007 May01 (STEREO B) 10-2 10-3 10-4 10-5 10-6 10-7 + STE D0 D1D2D3 ~ E-2.13 ~ E-2.07 Flux (cm2· s · sr · eV)-1 SEPT-E ~ E-1.1 103 104 105 106 Energy (eV)
160 120 80 40 \ 160 120 80 40 160 120 80 40 300 200 100 0 4.85 keV STEREO B 49 keV 1.0 0.6 0.2 STE ΦB PA PA PA 4.85 keV Normalized f 49 keV D2 D1 D0 D3 D3 D0 D1 D2 60 80 100 120 Pitch angle (degree) 22:00 23:00 00:00 2007 May 01
2007 May01 STEREO A + 10-2 10-3 10-4 10-5 10-6 10-7 STE D0 D1D2D3 ~ E-2.1 ~ E-1.94 Flux (cm2· s · sr · eV)-1 SEPT-E ~ E-1.16 103 104 105 106 Energy (eV)
120 80 40 0 \ 120 80 40 0 150 100 50 0 300 200 100 0 4.18 keV STEREO A 40 keV 1.0 0.6 0.2 40 keV STE ΦB PA PA PA Normalized f 4.18 keV D2 D1 D0 D3 D2 D1 D0 D3 40 60 80 100 Pitch angle (degree) 18:00 20:00 2007 May 01
2. Pick-up ions 2007 Jun18 STEREO B 10-1 10-2 10-3 \ 10-4 \ 10-5 \ 10-6 10-7 + ~ E-1.74 STE D0 D1D2D3 ~ E-2.1 ~ E-1.92 Flux (cm2· s · sr · eV)-1 SEPT-E ~ E-1.03 103 104 105 106 Energy (eV)
2. Pick-up ions 2007 Jun18 STEREO B 10-1 10-2 10-3 \ 10-4 \ 10-5 \ 10-6 10-7 + ~ E-1.74 STE D0 D1D2D3 ~ E-2.1 ~ E-1.92 Sun Flux (cm2· s · sr · eV)-1 2 1 0 3 D2 D1 SEPT-E D0 D3 ~ E-1.03 T 103 104 105 106 Energy (eV) R
150 100 50 0 150 100 50 0 300 200 100 0 4.85keV ΦB PA PA D2 D1 D0 D3 10:00 12:00 14:00 16:00 18:00 2007 Jun 18 (STEREO B )
150 100 50 0 150 100 50 0 300 200 100 0 4.85keV ΦB PA PA D2 D1 D0 D3 10:00 12:00 14:00 16:00 18:00 2007 Jun 18 (STEREO B )
150 100 50 0 150 100 50 0 300 200 100 0 5.68keV ΦB PA PA D2 D1 D0 D3 14:00 16:00 18:00 2007 Jun 18 (STEREO A )
150 100 50 0 150 100 50 0 300 200 100 0 5.68keV Sun ΦB PA PA 2 1 0 3 D2 D1 D0 D3 T R 14:00 16:00 18:00 2007 Jun 18 (STEREO A )
Sun SC SW ions Pick-up ions
Sun SC SW ions Pick-up ions
Sun Sun D3 690 km/s ~ 10 keV SC VSW = 500 km/s 960 km/s ~ 19 keV in the SW frame SW ions Assume He+ Pick-up ions
3. Ion beam traveling radially inward ? 2007 Aug19 STEREO B 10-1 10-2 10-3 \ 10-4 \ 10-5 \ 10-6 10-7 D2 + STE D0 D1D2D3 D1 ~ E-2.12 D0 D3 ~ E-1.98 Flux (cm2· s · sr · eV)-1 ~ E-1.94 SEPT-E ~ E-0.95 103 104 105 106 Energy (eV)
3. Particles traveling radially inward ? 2007 Aug19 STEREO B 10-1 10-2 10-3 \ 10-4 \ 10-5 \ 10-6 10-7 D2 + STE D0 D1D2D3 D1 ~ E-2.12 D0 D3 Sun ~ E-1.98 Flux (cm2· s · sr · eV)-1 ~ E-1.94 2 1 0 3 D2 D1 D0 SEPT-E D3 ~ E-0.95 T R 103 104 105 106 Energy (eV)
120 80 40 0 \\ 120 80 40 0 300 200 100 0 4.85keV D2 D1 D0 D3 ΦB PA PA 10:00 12:00 14:00 16:00 2007 Aug19 (STEREO B )
120 80 40 0 \\ 120 80 40 0 300 200 100 0 4.85keV D2 D1 D0 D3 ΦB PA PA 10:00 12:00 14:00 16:00 2007 Aug19 (STEREO B )
Sun D2 ~22 keV D1 ~21 keV D0 ~18 keV D3 690 km/s ~ 10 keV in the SC frame 870 km/s ~ 16 keV in the SW frame VSW = 350 km/s Assume He ions
Conclusions • Superthermal electron tail (~2-20 keV) in the solar wind during solar minimum: • Power law, ~ -2; isotropic • 2. Pick-up ions , ~ 20 keV (if He+) in the solar wind frame • 3. Ion beam traveling radially towards the Sun ??
102 101 100 \ 10-1 \ + STE D0 D1D2D3 Counts/s 103 104 105 Energy (eV)