HIFI Observations of Water in the Atmosphere of Comet C-2008 Q3 Garradd - Astrophysics > Earth and Planetary AstrophysicsReportar como inadecuado




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Abstract: High-resolution far-infrared and sub-millimetre spectroscopy of water linesis an important tool to understand the physical and chemical properties ofcometary atmospheres. We present observations of several rotational ortho- andpara-water transitions in comet C-2008 Q3 Garradd performed with HIFI onHerschel. These observations have provided the first detection of the2 {12}-1 {01} 1669 GHz ortho and 1 {11}-0 {00} 1113 GHz para transitions ofwater in a cometary spectrum. In addition, the ground-state transition1 {10}-1 {01} at 557 GHz is detected and mapped. By detecting several waterlines quasi-simultaneously and mapping their emission we can constrain theexcitation parameters in the coma. Synthetic line profiles are computed usingexcitation models which include excitation by collisions, solar infraredradiation, and radiation trapping. We obtain the gas kinetic temperature,constrain the electron density profile, and estimate the coma expansionvelocity by analyzing the map and line shapes. We derive water production ratesof 1.7-2.8 x 10^{28} s^{-1} over the range r h = 1.83-1.85 AU.



Autor: P. Hartogh, J. Crovisier, M. de Val-Borro, D. Bockelée-Morvan, N. Biver, D. C. Lis, R. Moreno, C. Jarchow, M. Rengel, M. Emprech

Fuente: https://arxiv.org/







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