A Herschel Study of D/H in Water in the Jupiter-family Comet 45P/Honda-Mrkos-Pajdušáková and Prospects for D/H Measurements with CCAT
Küppers, M.; Hartogh, P.; Crovisier, J.; Biver, N.; Bockelée-Morvan, D.; Lis, D. C.; Bergin, E. A.; Blake, G. A.; Jehin, E.; Manfroid, J.; Moreno, R.; Rengel, M.; de Val-Borro, M.; Szutowicz, S.
United States, France, Germany, Belgium, Spain, Poland
Abstract
We present Herschel observations of water isotopologues in the atmosphere of the Jupiter-family comet 45P/Honda-Mrkos-Pajdušáková. No HDO emission is detected, with a 3σ 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 4.5σ 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.