D. C. Lis, N. Biver, D. Bockelee-Morvan, P. Hartogh, E. A. Bergin, G. A. Blake, J. Crovisier, N. de Val-Borro, E. Jehin, M. Kuppers, J. Manfroid, R. Moreno, M. Rengel, S. Szutowicz
We present Herschel observations of water isotopologues in the atmosphere of the Jupiter-family comet 45P/Honda-Mrkos-Pajdusakova. No HDO emission is detected, with a 3 sigma upper limit of 2.0 10-4 for the D/H ratio. This value is consistent with the earlier Herschel measurement in the Jupiter-family comet 103P/Hartley 2. The canonical value of 3 10-4 measured pre-Herschel in a sample of Oort-cloud comets can be excluded at a 4.5 sigma level. The observations presented here further confirm that a diversity of D/H ratios exists in the comet population and emphasize the need for additional measurements with future ground-based facilities, such as CCAT, in the post-Herschel era.
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http://arxiv.org/abs/1307.6869
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