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5th Alfvén Conference

5th Alfvén Conference. on “Plasma Interaction with Non-magnetized Planets/Moons and its Influence on Planetary Evolution”. www.ep.sci.hokudai.ac.jp/~alfven5. 4-8 October, 2010 Sapporo, Japan. Mars, Venus, The Moon, and Jovian/Saturnian satellites.

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5th Alfvén Conference

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  1. 5th Alfvén Conference on “Plasma Interaction with Non-magnetized Planets/Moons and its Influence on Planetary Evolution” www.ep.sci.hokudai.ac.jp/~alfven5 4-8 October, 2010 Sapporo, Japan Mars, Venus, The Moon, and Jovian/Saturnian satellites

  2. Bowshock and Planetary Size: a Earth-Venus-Mars comparison M. Yamauchi et al., IRF-Kiruna Gyroradius vs Bow-shock size

  3. Bowshock / Foreshock = accelerated ions

  4. Outline 1. Venus ≈ Earth 2. Mars ≠ Venus/Earth

  5. Earth’s case= since 1970’s B

  6. , ∑ 3-min scan , ∑ 3-min scan , ∑ 3-min scan , ∑ 3-min scan SW SW SW SW BS BS BS BS e- (top) & H+ (rest) at different angle Venus we show this

  7. Venus ≈ Earth B 2006-6-18 B FS connected to BS = FS SW (=1) Scanning over -45°~+45°

  8. IMA looking direction VEX

  9. cf. Earth (Cao et al., 2008) FS ion * Upstream region * Energized (> Esw) * Localized (< few 100km) V// V// SW SW cluster-3 cluster-1 V V

  10. Venus ≈ Earth No internal magnetic field, no magnetosphere. Planet is the same size as the Earth.  Smaller bow shock size than the Earth, yet MHD regime. How about Mars? No internal magnetic field. Planet is smaller than the Earth.  The bow shock size is too small to treat with MHD

  11. Mars Foreshock case foot distance

  12. Detail of spectrogram (E=1~15 keV)  =4  =3  =2  =1 ring H+   =all Mixture of accelerated ion (H+) components

  13. 3rd // acc 2nd // acc main // acc pre-acc heating

  14. Classifying counts in // and  directions B (N-direction) is estimated from minimum variance method applied to the ring distribution

  15. 3rd // acc 2nd // acc main // acc pre-acc heating

  16. Two components 1. Field-aligned H+. 2. Gyrating H+ with large V//. Both types are found in the Terrestrial foreshock Venus: yes for entire upstream Mars: foot only!

  17. Special features for Mars • // beam observed only close to BS • Energy is stepping (due to reflection?) • Gyro-bunching effect (due to short distance?) with gradual  acceleration (why?)

  18. Three possible configurations and check multi-step acceleration (due to reflection) 2005-7-29 2005-7-12 2005-8-5

  19. Quasi- (case 1)

  20. Quasi-// (case 3)

  21. Summary Venus Express / ASPERA-4 often observes back-streaming H+ in the foreshock region of Venus, in a similar ways as the Terrestrial foreshock, i.e., field-aligned component, and intermediate (gyrating) component Mars Express / ASPERA-3 (same instrumentation as VEX) did not observe similar ions in the Martian foreshock region beyond the foot region. Instead, it shows different type of acceleration in the foot region, indicating the ion trajectory (history) during its gyromotion. The finite gyroradii effect makes Mars a perfect laboratory to study acceleration processes.

  22. End

  23. PA dist.  = 3~7 only

  24. Venus e- (top) & H+ (rest) at different angle , ∑ 3-min scan SW SW SW SW BS BS BS BS Scan=-45°~45°

  25. VEX connected by B not connected , ∑ 3-min scan BS SW BS

  26. case 3a

  27. case 3b

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