Physics of Cometary Nuclei after Rosetta

Horst Uwe Keller
Max Planck Institute（2006年に引退）

Their activity sets comets apart from all other planetary bodies. It took hundreds of years to realize that comets are interplanetary bodies consisting of dust and volatiles. Ground-braking interpretations in the middle of the last century made the tiny cometary nuclei well enough defined to target the first European (ESA) space mission (Giotto) at comet Halley in 1986. The nature of cometary nuclei - well preserved relicts from the times of planetary formation - changed from a "dirty snowball"to an "icy dirtball". This change of paradigm was only slowly accepted but confirmed by the NASA Deep Space mission, the next flyby mission 15 years after Giotto. The dominance of refractory material over the ice content makes it difficult to understand the physical processes that drive cometary activity. Over the following 20 years several flyby missions investigated cometary nuclei further while Europe pushed its cornerstone mission Rosetta to rendezvous the comet 67P/Churyumov-Gerasimenko. The two years long intensive observations from the onset of cometary activity to its maximum around perihelion and beyond revealed unprecedented details of the nucleus. The analysis and interpretation of the large amount of data is still ongoing and its actual status will be reviewed. How do the new findings about the physics of cometary nuclei and their activity compare to the results of the flyby missions?

Place: Bldg. A 1F Nyusatsu Conf. room（1134）/ A棟１F入札・会議室（1134室）

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