Öberg, KI;
Cleeves, LI;
Bergner, JB;
Cavanaro, J;
Teague, R;
Huang, J;
Loomis, RA;
... Wilner, DJ; + view all
(2021)
The TW Hya Rosetta Stone Project. I. Radial and Vertical Distributions of DCN and DCO⁺.
The Astronomical Journal
, 161
(1)
, Article 38. 10.3847/1538-3881/abc74d.
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Abstract
Molecular D/H ratios are frequently used to probe the chemical past of solar system volatiles. Yet it is unclear which parts of the solar nebula hosted an active deuterium fractionation chemistry. To address this question, we present 0farcs2–0farcs4 Atacama Large Millimeter/submillimeter Array (ALMA) observations of DCO+ and DCN 2–1, 3–2, and 4–3 toward the nearby protoplanetary disk around TW Hya, taken as part of the TW Hya Rosetta Stone project, augmented with archival data. DCO+ is characterized by an excitation temperature of ~40 K across the 70 au radius pebble disk, indicative of emission from a warm, elevated molecular layer. Tentatively, DCN is present at even higher temperatures. Both DCO+ and DCN present substantial emission cavities in the inner disk, while in the outer disk the DCO+ and DCN morphologies diverge: most DCN emission originates from a narrow ring peaking around 30 au, with some additional diffuse DCN emission present at larger radii, while DCO+ is present in a broad structured ring that extends past the pebble disk. Based on a set of simple parametric disk abundance models, these emission patterns can be explained by a near-constant DCN abundance exterior to the cavity, and an increasing DCO+ abundance with radius. In conclusion, the ALMA observations reveal an active deuterium fractionation chemistry in multiple disk regions around TW Hya, but not in the cold planetesimal-forming midplane and in the inner disk. More observations are needed to explore whether deuterium fractionation is actually absent in these latter regions, and if its absence is a common feature or something peculiar to the old TW Hya disk.
| Type: | Article |
|---|---|
| Title: | The TW Hya Rosetta Stone Project. I. Radial and Vertical Distributions of DCN and DCO⁺ |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-3881/abc74d |
| Publisher version: | https://doi.org/10.3847/1538-3881/abc74d |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Planet formation; Protoplanetary disks; Millimeter astronomy; Astrochemistry; Submillimeter astronomy; Interstellar molecules; Solar system formation |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10119441 |
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