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Campaign of research of small Kuiper Belt objects by stellar occultations

Campaign of research of small Kuiper Belt objects by stellar occultations. Roques, F., (1), Doressoundiram A. (1), Moncuquet M. (1), Chevreton M. (1), Colas, F. (2), Lecacheux, J.(1), Auvergne, M.(1) GP Tozzi (3), O. Hainault (4) (1) LESIA, Observatoire de Paris, 92195 Meudon (France)

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Campaign of research of small Kuiper Belt objects by stellar occultations

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  1. Campaign of research of small Kuiper Belt objects by stellar occultations Roques, F., (1), Doressoundiram A. (1), Moncuquet M. (1), Chevreton M. (1), Colas, F. (2), Lecacheux, J.(1), Auvergne, M.(1) GP Tozzi (3), O. Hainault (4) (1) LESIA, Observatoire de Paris, 92195 Meudon (France) (2) IMCCE, Observatoire de Paris, 92195 Meudon (France) (3) Oss. Astrofisico di Arcetri, Firenze (Italy) (4) European Southern Observatory • - Stellar occultations are diffracting phenomena • - A powerful tool to accede to invisible small KBO • - First results of the Pic du Midi campaign • - Prospective projects

  2. The shadow of the Kuiper Belt Objects Circular 1km KBO Elliptical 1km KBO Roques and Moncuquet, 2000

  3. Occultation profiles for different stars

  4. Amplitude variation of the stellar flux R* < Fresnel scale = √ (D/2) Roques and Moncuquet, 2000

  5. Amplitude variation of the stellar fux R* > Fresnel scale Roques and Moncuquet, 2000

  6. The detection of diffracting occultationsneedsHigh speed photometric observations The velocity of the KBO in the sky plane toward the opposition : 25 km/sec => Fast photometry (20 hz) is necessary • The noise (scintillation) limits the possibility to detect an occultation event • The simulations => depth of the occultation profiles • A 4 deep event is detectable •  => detectable KBO • 0.01 => 120 meters KBO • 0.001 => 40 meters KBO

  7. Occultations rates TAOS T4M T8M space

  8. Telescopes sizes and constraint onq • The noise is due to scintillation: = S0 .d-2/3.X3/2.e-h/H0.(2 )-1/2 T2M :  =0.02 T4M :  =0.01 T8M :  =0.001

  9. Observations PIC 2000-2003 • Method : cumulative observations • homogeneous data processing=>4- events • comparison with estimations • 2 telescopes: T-2m and T-1m • Multi-objects photometers: • - a target star • - a comparison star • - sky • Ecliptic latitude = 0.2 °- r* =50m • 20 Hz • 09/2000(7 nights) +03/2003 (7 nights)

  10. Observations PIC 2000T2m data Stellar flux  (5 mn) • 15 hours of data with  better than 0.02 (T-2m) and  = 0.027 (T-1m)

  11. Observations PIC 2003 • 12 hours of data with  better than 0.02 (T-2m)

  12. Observations PIC 2000-2003 • 27 hours of observations • and • 4- level of detection • => • Estimation of occultation rate : • 0.4 (q = 3) • 2 (q = 4) • 4 (q = 4.5) 0 detection

  13. Observations PIC 2000-2003 A potential event (3-) compatible with a 150 meter KBO q = 4 q = 3 log(rate) log(depth)

  14. COROT Launch : 2005 EDDINGTON (one month) : hundreds of KBO, 15 m - 5 km

  15. Prospective-chromaticity-  = 0.4m  = 1.2m • = 0.01 (4.m telescope) - r = 100 m Information on the Fresnal scale, then, on the distance of the KBO

  16. Prospective : 8 meters telescope - space Fast phtometry 20-100 Hz needed! • = 0.001 (8-m telescope) - r = 40m Information on the size and distance of the KBO

  17. ProspectiveDistants objects : Oort cloud A 4 km Oort cloud object at 10 4 AU

  18. Future projects • Campaign on the TBL telescopes • Larges telescopes => pb : fast photometry • Technical data : guiding cameras ESO-VLT • Space : Corot, Eddington, dedicated instrument

  19. Conclusions • Stellar occultations give a zoom on planétésimals :kilometer and sub-kilometer Kuiper Belt objects • Diffracting occultations are accessible from ground-based telescopes • Campaign on Pic du Midi 2000-2003 : • zero 4 event on 27 h => first constraint on q • one potentiel event (150 meters KBO) • Large Telescopes + fast photometry (20 hz) =>??? • Space : high precision photometry missions (Corot - Eddington) • Dedicated instrument/mission

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