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Final results of HDAC analysis

Final results of HDAC analysis. P. Hedelt (1) , Y. Ito (2,3) , H. U. Keller (2) , R. Reulke (3) , P. Wurz (4) , H. Lammer (5) , H. Rauer (1,6) , L. Esposito (7) Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt (DLR)

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Final results of HDAC analysis

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  1. Final results of HDAC analysis P. Hedelt(1), Y. Ito(2,3), H. U. Keller(2), R. Reulke(3), P. Wurz(4), H. Lammer(5), H. Rauer(1,6), L. Esposito(7) Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt (DLR) Max Planck Institut für Sonnensystemforschung (MPS) Japan Manned Space Systems Corporation, Tsukuba, Japan Institut für Verkehrsforschung, Deutsches Zentrum für Luft- und Raumfahrt (DLR) Abteilung für Weltraumforschung und Planetologie, Universität Bern Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften Zentrum für Astronomie und Astrophysik, Technische Universität Berlin (TUB) Laboratory forAtmosphericand Space Physics, University of Colorado

  2. HDAC T9 measurement UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 2 2 2 2 2 2 2

  3. Difference signal UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 3 3 3 3 3 3 3 3

  4. Radiative transfer modeling UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt Parameter variation: • Exosphere atomic hydrogen distribution: • Chamberlain model (Chamberlain, 1963) • Particle Monte Carlo model (Wurz & Lammer, 2003) • Exobase hydrogen density • Exospheric temperature  Fit to data 4 4 4 4 4 4 4 4 4

  5. Exospheric densities Particle model H Chamberlain model CH4 UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 5 5 5 5 5 5 5 5 5

  6. Density Variation UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt • Exobase densities in the literature • nH = 4.2x103 cm-3 (Yung, 1984 - model) • nH = 8.0x103 cm-3 (Toublanc, 1995 - model) • nH = 1.0x104 cm-3 (Broadfoot, et al. 1981 - data) • nH = 4.6x104 cm-3 (Garnier, et al. 2007 - model) • nH = 7.0x104 cm-3 (Krasnopolsky, et al. 2009 - model) • nH = 8.0x104 cm-3 (De la Haye, et al., 2007 - model) 6 6 6 6 6 6 6 6 6 6 6

  7. Density Variation UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt Chamberlain Model 7 7 7 7 7 7 7 7 7 7 7

  8. Density Variation UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt Particle Model 8 8 8 8 8 8 8 8 8 8 8

  9. Difference signal during c/a Particle model Chamberlain model UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 9 9 9 9 9 9 9 9 9 9

  10. Difference signal during ingress Chamberlain model Particle model UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 10 10 10 10 10 10 10 10 10 10

  11. Temperature Variation UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt • Exospheretemperatures in theliterature: • De la Haye et al. (2008): • 152.8 ± 4.6 K (TA) • 149.0 ± 9.2 K (TB) • 157.4 ± 4.8 (T5) 11 11 11 11 11 11 11 11 11 11 11 11

  12. Temperature Variation Exobase H density: 8x104 cm-3, Particle model profile UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 12 12 12 12 12 12 12 12 12 12 12 12

  13. Fit to data UVIS Team Meeting 2009 Pascal Hedelt Best fitting density distribution using least squares fit: Particle model: Exobase H density nH=9x104 cm-3 Chamberlain model: Exobase density nH=2x104 cm-3 13 13 13 13 13 13 13 13 13 13 13 13 13

  14. Fit to data: Chamberlain model UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 14 14 14 14 14 14

  15. Fit to data: Particle model UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 15 15 15 15 15 15

  16. Best fitting H profile Particle model Chamberlain model UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 16 16 16 16 16 16

  17. Comparison with measurement UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 17 17 17 17 17 17

  18. Comparison with measurement:Removing the background UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 18 18 18 18 18 18

  19. Summary & Conclusion UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt Good agreement between model and data Exospheric temperature has no influence  Best fit using Chamberlain model: nH,Exobase= 2.0x104 cm-3 validated for Earth only, static model  Best fit using Particle MC model: nH,Exobase= 9.0x104 cm-3 validated for Mercury & Mars, dynamic model From latest calculations (De la Haye, et al. 2007): nH,Exobase= 8.0x104 cm-3  Good agreement with Particle model distribution Background signal in HDAC data: about 12,000 cts (430 R) Titan Lyman α dayside brightness: 179±10 R (Ajello, et al. 2008: 208 R) nightside brightness: 50±4 R (Ajello, et al. 2008: 80 R) Using HDAC data we are able to determine atomic hydrogen distribution in Titan’s exosphere!!! 19

  20. Outlook: T66 & T67 UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 20 20

  21. Outlook: T66 & T67 UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt 21 21

  22. UVIS Team Meeting 2009 Pascal Hedelt Thanks for your attention!

  23. Aims & Scope UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt • Using HDAC data gathered during T9, the distribution of atomic hydrogen in Titans exosphere is investigated: • Calculate exospheric emission of resonantly scattered Hydrogen Ly-Alpha from Titan • Simulate HDAC measurement during the Cassini/Titan T9 encounter • Little is known about Titan‘s hydrogen exosphere • Vary input parameters • Determine exospheric parameters 24 24 24 24 24 24 24

  24. Radiative transfer model (1) Apply Monte Carlo to solve RTE: • 40,000,000 photons started at sunlit side of upper exosphere layer • Scattered by H (isotropically) • Absorbed by CH4 • Trace until: • Absorbed by methane • Reach model boundaries • Store scattering positions + WL + Directions

  25. Radiative transfer model (2) Simulate T9 flyby: Apply „splitting“ technique:Photons are emitted in direction of detector Calculate transmission to detector Apply HDAC absorption pattern

  26. Density model description UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting, Boulder, Colorado 2008/06/22-24 Pascal Hedelt UVIS Team Meeting 2009 Pascal Hedelt • Chamberlain model • Maxwellian velocity distribution at exobase • Use Liouville theorem to derive exospheric densities • Static contribution of ballistic/escaping orbits • Particle MC model • Maxwellian velocity distribution at exobase • Dynamic MC approach, single particles started at exobase with random energy & ejection angle 27 27 27 27 27 27 27 27 27 27

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