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| EPoS Contribution |
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Deuterated water in low-mass protostars
Audrey Coutens Institut de Recherche en Astrophysique et Planetologie, Toulouse, France | |
| Observations of deuterated water are an important complement for studies of H2O, since they give strong constraints on the formation processes (grain surfaces versus gas-phase chemistry) and because of its link with the comets and the Earth's oceans. The CHESS (Chemical HErschel Surveys of Star forming regions) Key Program has allowed to detect a lot of transitions of HDO and H2O as well as its isotopes H2-18O and H2-17O towards the low-mass protostar IRAS16293-2422 thanks to the unbiaised spectral survey carried out with the HIFI instrument on board the Herschel Space Observatory. Complementary data of HDO from the ground-based telescopes IRAM and JCMT are also available. In total, 13 HDO lines have been detected towards IRAS16293-2422. It is the first time that so many HDO lines are detected towards a same source, allowing a precise determination of the abundance of deuterated water through the protostar envelope. To reproduce the observed line profiles, we have performed a modeling of HDO from the hot corino to the surrounding envelope using the physical structure of the protostar and the spherical non-LTE Monte-Carlo radiative transfer code RATRAN, which takes also radiative pumping by continuum emission from dust into account. The same method has been applied to model the water isotopes H2-18O and H2-17O. We will show the results of this analysis and discuss the determined HDO/H2O ratio. We will also present a comparison with other low-mass protostars such as NGC1333-IRAS4A and IRAS4B, for which new HDO data have recently been observed. | |
| Collaborators: C. Vastel, IRAP, France E. Caux, IRAP, France |
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