Universität zu Köln

Lis, Dariusz C., Bockelee-Morvan, Dominique, Guesten, Rolf, Biver, Nicolas, Stutzki, Juergen, Delorme, Yan, Duran, Carlos, Wiesemeyer, Helmut ORCID: 0000-0002-5135-8657 and Okada, Yoko ORCID: 0000-0002-6838-6435 (2019). Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets. Astron. Astrophys., 625. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

The D/H ratio in cometary water has been shown to vary between 1 and 3 times the Earth's oceans value, in both Oort cloud comets and Jupiter-family comets originating from the Kuiper belt. This has been taken as evidence that comets contributed a relatively small fraction of the terrestrial water. We present new sensitive spectroscopic observations of water isotopologues in the Jupiter-family comet 46P/Wirtanen carried out using the GREAT spectrometer aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The derived D/H ratio of (1.61 +/- 0.65) x 10(-4) is the same as in the Earth's oceans. Although the statistics are limited, we show that interesting trends are already becoming apparent in the existing data. A clear anti-correlation is seen between the D/H ratio and the active fraction, defined as the ratio of the active surface area to the total nucleus surface. Comets with an active fraction above 0.5 typically have D/H ratios in water consistent with the terrestrial value. These hyperactive comets, such as 46P/Wirtanen, require an additional source of water vapor in their coma, explained by the presence of subliming icy grains expelled from the nucleus. The observed correlation may suggest that hyperactive comets belong to a population of ice-rich objects that formed just outside the snow line, or in the outermost regions of the solar nebula, from water thermally reprocessed in the inner disk that was transported outward during the early disk evolution. The observed anti-correlation between the active fraction and the nucleus size seems to argue against the first interpretation, as planetesimals near the snow line are expected to undergo rapid growth. Alternatively, isotopic properties of water outgassed from the nucleus and icy grains may be different due to fractionation effects at sublimation. In this case, all comets may share the same Earth-like D/H ratio in water, with profound implications for the early solar system and the origin of Earth's oceans.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Lis, Dariusz C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bockelee-Morvan, Dominique UNSPECIFIED UNSPECIFIED UNSPECIFIED Guesten, Rolf UNSPECIFIED UNSPECIFIED UNSPECIFIED Biver, Nicolas UNSPECIFIED UNSPECIFIED UNSPECIFIED Stutzki, Juergen UNSPECIFIED UNSPECIFIED UNSPECIFIED Delorme, Yan UNSPECIFIED UNSPECIFIED UNSPECIFIED Duran, Carlos UNSPECIFIED UNSPECIFIED UNSPECIFIED Wiesemeyer, Helmut UNSPECIFIED orcid.org/0000-0002-5135-8657 UNSPECIFIED Okada, Yoko UNSPECIFIED orcid.org/0000-0002-6838-6435 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-148077
DOI:	10.1051/0004-6361/201935554
Journal or Publication Title:	Astron. Astrophys.
Volume:	625
Date:	2019
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language 1996 B2 HYAKUTAKE; DEUTERATED WATER; SOLAR NEBULA; D/H RATIO; COMA; NUCLEUS; SUBMILLIMETER; ORIGIN; VIEW; MASS Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14807