Neutral Na in cometary tails as a remnant of early aqueous alteration

Y. Ellinger, F. Pauzat, O. Mousis, A. Guilbert-Lepoutre, F. Leblanc, M. Ali-Dib, M. Doronin, E. Zicler, A. Doressoundiram

    Research output: Contribution to journalArticlepeer-review


    Observations of comet C/1995O1 Hale-Bopp during the spring of 1997 led to the discovery of a neutral sodium tail whose origin is still not clearly understood. Here, we propose an interpretation for the origin ofthis sodium tail, which is based upon chemical grounds. Starting from Na+ trapped chemically during the condensation of refractory material in the protosolar nebula to its incorporation in the building blocks of comets and its transfer from refractory to volatile phases in the nucleus due to aqueous alteration, we follow the chemical path of sodium until its transformation into a neutral atom when released from the sublimating cometary ice. We propose that two Na reservoirs should coexist in a comet: one coming from the refractory dust, the other one from the icy matrix. Their relative importance would depend on the extent of the zone where liquid water formed within the nucleus and the time during which water remained liquid, thus favoring the Na+ exchange between rocks and ice. These two key parameters would in turn strongly depend on the thermal history of the comet (amounts of radiogenic nuclides, orbital history, etc.). If our model is correct, the detection of Na originating from water ice would be a testimonial of the past aqueous alteration of the comet or its parent body.

    Original languageEnglish (US)
    Article numberL30
    JournalAstrophysical Journal Letters
    Issue number2
    StatePublished - Mar 10 2015


    • Kuiper Belt: general
    • Oort Cloud
    • astrochemistry
    • comets: general
    • protoplanetary disks

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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