The Dusty View of DI from ESO Chile

Christiaan Sterken, Hermann Boenhardt

    Research output: Chapter in Book/Report/Conference proceedingConference paper

    Abstract

    Around the time of the impact of NASA's Deep Impact (DI) mission at comet
    9P/Tempel 1, in total 6 telescopes with altogether 7 different instruments,
    located at the La Silla (LSO) and Paranal (VLT) Observatories of the European
    Southern Observatory (ESO) in Chile, were used to characterize the dust
    properties before and after the event. The ejecta cloud expanded at an average
    speed of about 200 ms$^{-1}$ during the first hours after the event. It
    reached stagnation distance of 25000 km about 3 days after impact. The
    pre-impact dust jet and fan activity ('porcupine' pattern) remained
    undisturbed after impact. In our measurements the jet activity can be traced
    to a few 100 km nucleus distance. In total 9 comastructures are identified
    which may originate from at least 4 regions of enhanced dust emission on the
    nucleus -- one of this region may in fact be multiple. No obvious signatures
    of a new active region created by DI are found. The overall dust production
    during the impact compares to about 5--10~h of normal activity. The global
    expansion geometry of the DI cloud is compatible with a majority of dust
    grains in the micron size range. Indications exist for asymmetric brightness
    and colour distributions of the dust in the ejecta cloud. The dust temperature
    rose from about 280--290 K before to 330 K one day after the event and fell to
    pre-impact level the day thereafter. The dust reflected sunlight was found to
    be linearly polarized at about 7.5% in
    the visible and near--IR, at constant level within about 4000~km from the
    nucleus. No circular polarization of the dust is detected.
    Original languageEnglish
    Title of host publicationDeep Impact as a World Observatory Event. Synergies in Space, Time and Wavelength
    Pages147-154
    Number of pages8
    Publication statusPublished - 2009
    EventFinds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet - Stockholm, Sweden
    Duration: 21 Sep 200925 Sep 2009

    Conference

    ConferenceFinds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet
    Country/TerritorySweden
    CityStockholm
    Period21/09/0925/09/09

    Keywords

    • comets
    • Deep Impact

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