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Akademie věd České republiky |
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Akademie věd České republiky |
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Mimořádný seminář 23. 3. 2006
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který se koná ve čtvrtek dne v zasedací místnosti Kosmické laboratoře AsÚ v Ondřejově PROGRAM: The Diversity of Multiple asteroidal System Studied by Adaptive Optics Observations Dr. Franck Marchis (Department of Astronomy, UC Berkeley) After decades of speculation, the existence of binary asteroids has been observationally confirmed thanks mostly to the development of adaptive optics on ground-based telescopes, with examples in all minor planet populations. During this talk, I will describe the results of our observing campaign initiated in 2004, and performed with both ESO VLT-8m and Keck-10 m telescopes and their Adaptive Optics systems, that is aimed at characterizing the orbits of known binary asteroid systems. Our study shows a large diversity in the orbits of 9 main-belt systems (45 Eugenia, 87 Sylvia, 90 Antiope, 107 Camilla, 121 Hermione, 130 Elektra, 283 Emma, 379 Huenna, 3749 Balam). I will describe various scenarios of formation envisioned based on the orbital parameters of the satellite. The discovery of a smaller second moonlet, Remus – orbiting closer to 87 Sylvia than Romulus (known since 2001) – will be also discussed. Finally I will show how the orbit of 617 Patroclus, the only known binary Trojan, estimated through Keck Laser Guide Star AO observations yields to a low bulk density suggesting either very porous internal structure or that the asteroid is composed mostly of water ice. Srdečně zve Petr Pravec Vladimír Karas |