Water vapour jets inside the plume of gas leaving Enceladus

    Authors

    C. J. Hansen; L. W. Esposito; A. I. F. Stewart; B. Meinke; B. Wallis; J. E. Colwell; A. R. Hendrix; K. Larsen; W. Pryor;F. Tian

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    Abstract

    A plume of water vapour escapes from fissures crossing the south polar region of the Saturnian moon Enceladus(1-6). Tidal deformation of a thin surface crust above an internal ocean could result in tensile and compressive stresses that would affect the width of the fissures(7); therefore, the quantity of water vapour released at different locations in Enceladus' eccentric orbit is a crucial measurement of tidal control of venting. Here we report observations of an occultation of a star by the plume on 24 October 2007 that revealed four high- density gas jets superimposed on the background plume. The gas jet positions coincide with those of dust jets reported elsewhere(8) inside the plume. The maximum water column density in the plume is about twice the density reported earlier(2). The density ratio does not agree with predictions(7)-we should have seen less water than was observed in 2005. The ratio of the jets' bulk vertical velocities to their thermal velocities is 1.5 +/- 0.2, which supports the hypothesis that the source of the plume is liquid water, with gas accelerated to supersonic velocity in nozzle- like channels(9).

    Journal Title

    Nature

    Volume

    456

    Issue/Number

    7221

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    477

    Last Page

    479

    WOS Identifier

    WOS:000261170500032

    ISSN

    0028-0836

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