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Bruno Sicardy Obs. Paris - LESIA and occcultation Team

PHYSIQUE DE L'ATMOSPHÈRE DE PLUTON ET TAILLE DE CHARON DÉDUITES D'OCCULTATIONS STELLAIRES 2002-2006. Bruno Sicardy Obs. Paris - LESIA and occcultation Team. Thomas Widemann. François Colas. Atelier 3ème zone, Nantes 11-12 janvier 2007. Pluto and Charon probed by occultations.

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Bruno Sicardy Obs. Paris - LESIA and occcultation Team

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  1. PHYSIQUE DE L'ATMOSPHÈRE DE PLUTON ET TAILLE DE CHARON DÉDUITESD'OCCULTATIONS STELLAIRES 2002-2006 Bruno Sicardy Obs. Paris - LESIA and occcultation Team Thomas Widemann François Colas Atelier 3ème zone, Nantes 11-12 janvier 2007

  2. Pluto and Charon probed by occultations special moment: equinox in 1988, perihelium in 1989 (period 248 years)  effects on N2 pressure-equilibirum atmosphere? Charon's size? ( density ?) Charon's surface gravity ~ 1/2 Pluto's gravity  possibility of atmosphere?

  3. complex interplay of large distance variations & drastic seasonal effects C.J Hansen & D.A. Paige Icarus, 120, 247-265 (1996)

  4. 2001 2011 2020 Pluto motion in the sky

  5. Pluton 20 juil. 2002

  6. P131.1 August 21, 2002

  7. Sicardy et al. Nature, 10 July 2003 spikes: scintillation in Pluto’s atmosphere warmer near pole temperature contrast: cooler near equator

  8. Sicardy et al.Nature, July 2003 Imm. Eme. 

  9. Sicardy et al. « Large changes in Pluto’s atmosphere as revealed by recent stellar occultations » Nature, 10 July 2003

  10. 2006 ? 2002 pressure doubled! 1988

  11. rP 1988 B'P 2002 2006 rN Time

  12. C.J Hansen & D.A. Paige Icarus, 120, 247-265 (1996)  10 bar  1 bar 0.1 bar 1900 2000 2100

  13. Pluto in 1988

  14. Pluto in 2002

  15. measuring Charon

  16. 0.89" 2UCAC 26257135 (D. Herald, Aug. 2004)

  17. VLT/NACO K band, Charon occultation 11 July 2005 Pluto 1" star + Charon

  18. R= 603.61.4 km Sicardy et al., Nature439, 52, 2006 « Charon’s size and an upper limit on its atmosphere from a stellar occultation »

  19. 100 K - CH4 56 K - N2 56 K

  20. Some conclusions: • Atmosphere: limit is model dependent, e.g. CH4 with inversion layer: psurf < 15 nbar …or… N2 isothermal 56 K: psurf < 110 nbar etc… • Charon’s size:RC = 603.6  1.4 km • Charon’s density:C = 1.65  0.06 g cm-3 (taken from Buie et al. AJ. 132, 290, 2006, NB. P = 2.03  0.06 g cm-3forPluto) • Possibility to retrieve Pluto’s radius with accurate Charon’s accurate size --> refine atmospheric model

  21. recent & future stuff…

  22. 12 June 2006 Pluto occultation

  23. 1988 2002

  24. 12 June 2006, Australia Stockport Blue Mountains Hobart

  25. Stockport 50 cm 20 cm Blue Mountains 40 cm Hobart Time (sec UT)

  26. 99.7% c.l. 2 68.3% c.l. pressure expansion factor since 2002

  27. 1988 2002

  28. 2006

  29. 10 5 2 1 pressure @ 1215 km (bar) Hansen & Paige, Icarus 120, 247 (1996) New Horizon 2006 2002 1988 time (year)

  30. 2007: four Pluto & co events?

  31. Nix, 22 mars 2007

  32. Hydra 2.1"

  33. Pluto **et** Hydra 12 mai 2007 Paranal & La Silla Pluton 14 juin 2007 Paranal, La Silla & SOAR

  34. en cours: prédictions d'occultations par de gros TNO Eris, 2005 FY9, 2003 EL6, Sedna, Orcus, Quaoar, Varuna, … (voir présentation T. Widemann)

  35. … merci Paranal Jul 2005

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