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Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta |
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| Authors: | Horst Uwe Keller Sonia Fornasier Stubbe F Hviid Jörg Knollenberg Miriam Rengel Gabriele Cremonese Detlef Koschny Ekkehard Kührt Holger Sierks Cesare Barbieri Hans Rickman Michael F A'Hearn Maria-Antonella Barucci Vania da Deppo Björn JR Davidsson Stefano Debei Fritz Gliem José J Lopez Moreno Giampiero Naletto Angel Sanz Andrés |
| Institution: | a Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany b Dipartimento di Astronomia and CISAS, Università di Padova, Vicolo dell'Osservatorio 5, 35100 Padova, Italy c Instituto de Astrofísica de Andalucía - CSIC, C/Camino Bajo de Huétor, 50, 18008 Granada, Spain d Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, Les Trois Lucs BP 8, 13376 Marseille, France e DLR Institut für Planetenerkundung, Rutherfordstr. 2, 12489 Berlin, Germany f Queen's University, Astrophysics Research Centre, Department of Physics and Astronomy, Belfast BT7 1NN, United Kingdom g INAF - Astronomical Observatory of Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy h Institute of Space Science, National Central University, 32054 Chung Li, Taiwan i Research and Scientific Support Department of the European Space Agency, ESTEC, Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands j Physikalisches Institut, Abteilung Weltraumforschung und Planetologie, Universität Bern, Sidlerstr. 5, 3012 Bern, Switzerland k Department of Astronomy and Space Physics, Box 51575120, Uppsala, Sweden l Department of Astronomy, University of Maryland, MD 20742-2421, USA m Dipartimento di Ingegneria Meccanica, 6° piano, via Venezia 1, 35131 Padova, Italy n Observatoire de Paris, Section de Meudon, 92195 Meudon, France o Service d'Aéronomie du CNRS, Route des Gatines, BP 3, 91371 Verrières-le-Buisson, France p CNR-INFM Luxor, Via Gradenigo 6/B, 35131 Padova, Italy q Department of Information Engineering (DEI), University of Padova, Via Gradenigo 6/B, 35131 Padova, Italy r Facultà Ingegneria, Università degli Studi di Trento, Via Mesiano 77, 38050 Trento, Italy s INAF - Osservatorio Astronomico de Trieste, Via Tiepolo 11, 34014 Trieste, Italy t Institutut für Datentechnik und Kommunikationsnetzt, Technische Universität Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig, Germany u Department of Physics “G. Galilei,” Via Marzolo 8, 35131 Padova, Italy v Instituto Nacional de Técnica Aerospacial, Carreterade Ajalvir, p.k. 4, 28850 Torrejon de Ardoz (Madrid), Spain w Universidad Politécnica de Madrid, Instituto Ignacio D'Riva, Plaza Cardenal Cisneros s/n, 28040 Madrid, Spain |
| Abstract: | The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impact projectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showed regular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness of Tempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structures were created by the impact. Most of the material moved with  . Much of it left the comet in the form of icy grains which sublimated and fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet ( of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions with gas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations of the density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain. |
| Keywords: | Comet Tempel-1 Comets coma Impact processes |
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