^1,2,3Jonathan Fraine,^1,4Drake Deming,³Bjorn Benneke,³Heather Knutson,²Andrés Jordán,²Néstor Espinoza,⁵Nikku Madhusudhan,¹Ashlee Wilkins⁶Kamen Todorov

¹Department of Astronomy, University of Maryland, College Park, Maryland 20742-2421, USA
²Instituto de Astrofísica, Pontificia Universidad Católica de Chile, 7820436 Macul, Santiago, Chile
³Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
⁴NASA Astrobiology Institute’s Virtual Planetary Laboratory, Seattle, Washington 98195, USA
⁵Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁶Department of Physics, ETH Zürich, 8049 Zürich, Switzerland

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Reference
Fraine J, Deming D, Benneke B, Knutson H, Jordán A, Espinoza N, Madhusudhan N, Wilkins A, Todorov K (2014) Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet. Nature 513, 526–529
Link to Article [doi:10.1038/nature13785 ]

¹L. Ilsedore Cleeves, ¹ Edwin A. Bergin, ² Conel M. O’D. Alexander,¹Fujun Du, ³Dawn Graninger, ³Karin I. Öberg, ⁴Tim J. Harries
¹Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Avenue, Ann Arbor, MI 48109, USA.
²Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.
³Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA 02138, USA.
⁴Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

Identifying the source of Earth’s water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Using a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, which curtails the disk’s deuterated water formation and its viability as the sole source for the solar system’s water. This finding implies that, if the solar system’s formation was typical, abundant interstellar ices are available to all nascent planetary systems.

Reference
Cleeves LI, Bergin EA, Alexander CMOD, Du F, Graninger D, Öberg KI, Harries TJ (2014) The ancient heritage of water ice in the solar System. Science 345, 1590-1593
Link to Article [DOI: 10.1126/science.1258055]

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