¹⁶O/¹⁸O ratio in water in the coma of comet 67P/Churyumov-Gerasimenko measured with the Rosetta/ROSINA double-focusing mass spectrometer

Isaac R. H. G. Schroeder I (1) , Kathrin Altwegg (1, 2) , Hans Balsiger (1) , Jean-Jacques Berthelier (3) , Johan de Keyser (4) , Björn Fiethe (5) , Stephen A. Fuselier (6, 7) , Sébastien Gasc (1) , Tamas I. Gombosi (8) , Martin Rubin (1) , Thierry Sémon (1) , Chia-Yu Tzou (1) , Susanne Wampfler (2) , Peter Wurz (1, 2)

1 Physikalisches Institut [Bern]
2 CSH - Center for Space and Habitability
3 PLANETO - LATMOS
4 BIRA-IASB - Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique
5 IDA - Institute of Computer and Network Engineering [Braunschweig]
6 SwRI - Southwest Research Institute [San Antonio]
7 UTSA - The University of Texas at San Antonio
8 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]

The European Space Agency spacecraft Rosetta accompanied the Jupiter-family comet 67P/Churyumov-Gerasimenko for over 2 yr along its trajectory through the inner solar system. Between 2014 and 2016, it performed almost continuous in situ measurements of the comet’s gaseous atmosphere in close proximity to its nucleus. In this study, the ¹⁶O/¹⁸O ratio of H₂O in the coma of 67P/Churyumov-Gerasimenko, as measured by the ROSINA DFMS mass spectrometer onboard Rosetta, was determined from the ratio of H₂16O/H₂¹⁸O and ¹⁶OH/¹⁸OH. The value of 445 ± 35 represents an ~11% enrichment of ^{18<:sup>O compared with the terrestrial ratio of 498.7 ± 0.1. This cometary value is consistent with the comet containing primordial water, in accordance with leading self-shielding models. These models predict primordial water to be between 5 and 20% enriched in heavier oxygen isotopes compared to terrestrial water.}

Domains: Astrophysics [astro-ph]

Isaac R. H. G. Schroeder I, Kathrin Altwegg, Hans Balsiger, Jean-Jacques Berthelier, Johan de Keyser, et al.. ¹⁶O/¹⁸O ratio in water in the coma of comet 67P/Churyumov-Gerasimenko measured with the Rosetta/ROSINA double-focusing mass spectrometer. Astronomy and Astrophysics - A&A, 2019, 630, A29 (11 p.). ⟨10.1051/0004-6361/201833806⟩. ⟨insu-01877503⟩