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Discovery of a primordial water reservoir in the envelope of HH 211

Published online by Cambridge University Press:  13 January 2020

Odysseas Dionatos Open the ORCID record for Odysseas Dionatos [Opens in a new window]
Odysseas Dionatos*
Affiliation:
Department of Astrophysics, University of Vienna, Türkenschanzstrasse. 17, 1180 Vienna, Austria email: odysseas.dionatos@univie.ac.at
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Abstract

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We report on the detection of a rich water reservoir in the protostellar envelope of the Class 0 source HH211. In striking contrast to all other molecules detected with Herschel/PACS, water emission peaks around the central source where both ortho and para forms are detected. The measured ortho-to-para ratio of just 0.65 indicates formation of water-ice at very low temperatures and a non-destructive photo-desorption process around the protostar. While part of the H2O emission is likely related to collisional excitation, the centralized morphology around the protostar suggests that radiative excitation is also significant, despite the fact that radiation appears to have a very different impact on the H2O molecules when compared to the terminal outflow shocks. The very low ortho-to-para ratio suggests that H2O around the protostar originates from primordial envelope material that has never been thermally processed before.

Keywords

stars: formationISM: moleculesISM: abundancesISM: individual (HH 211)
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S345: Origins: From the Protosun to the First Steps of Life , August 2018 , pp. 252 - 254
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
© International Astronomical Union 2020

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