Cold Deuterium Fractionation in the Nearest Planet-forming Disk
Deuterium fractionation provides a window into the thermal history of volatiles in the solar system and protoplanetary disks. While evidence of active molecular deuteration has been observed toward a handful of disks, it remains unclear whether this chemistry affects the composition of forming plane...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/aca765 |
| _version_ | 1827122602505666560 |
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| author | Carlos E. Romero-Mirza Karin I. Öberg Charles J. Law Richard Teague Yuri Aikawa Jennifer B. Bergner David J. Wilner Jane Huang Viviana V. Guzmán L. Ilsedore Cleeves |
| author_facet | Carlos E. Romero-Mirza Karin I. Öberg Charles J. Law Richard Teague Yuri Aikawa Jennifer B. Bergner David J. Wilner Jane Huang Viviana V. Guzmán L. Ilsedore Cleeves |
| author_sort | Carlos E. Romero-Mirza |
| collection | DOAJ |
| description | Deuterium fractionation provides a window into the thermal history of volatiles in the solar system and protoplanetary disks. While evidence of active molecular deuteration has been observed toward a handful of disks, it remains unclear whether this chemistry affects the composition of forming planetesimals due to limited observational constraints on the radial and vertical distribution of deuterated molecules. To shed light on this question, we introduce new Atacama Large Millimeter/submillimeter Array observations of DCO ^+ and DCN J = 2–1 at an angular resolution of 0.″5 (30 au) and combine them with archival data of higher energy transitions toward the protoplanetary disk around TW Hya. We carry out a radial excitation analysis assuming both LTE and non-LTE to localize the physical conditions traced by DCO ^+ and DCN emission in the disk, thus assessing deuterium fractionation efficiencies and pathways at different disk locations. We find similar disk-averaged column densities of 1.9 × 10 ^12 and 9.8 × 10 ^11 cm ^−2 for DCO ^+ and DCN, with typical kinetic temperatures for both molecules of 20–30 K, indicating a common origin near the comet- and planet-forming midplane. The observed DCO ^+ /DCN abundance ratio, combined with recent modeling results, provide tentative evidence of a gas-phase C/O enhancement within <40 au. Observations of DCO ^+ and DCN in other disks, as well as HCN and HCO ^+ , will be necessary to place the trends exhibited by TW Hya in context, and fully constrain the main deuteration mechanisms in disks. |
| first_indexed | 2024-03-12T04:33:43Z |
| format | Article |
| id | doaj.art-48ac0a8ad0eb42f7ade8d646c70f6ab8 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2025-03-20T14:11:38Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-48ac0a8ad0eb42f7ade8d646c70f6ab82024-09-10T13:55:21ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194313510.3847/1538-4357/aca765Cold Deuterium Fractionation in the Nearest Planet-forming DiskCarlos E. Romero-Mirza0https://orcid.org/0000-0001-7152-9794Karin I. Öberg1https://orcid.org/0000-0001-8798-1347Charles J. Law2https://orcid.org/0000-0003-1413-1776Richard Teague3https://orcid.org/0000-0003-1534-5186Yuri Aikawa4https://orcid.org/0000-0003-3283-6884Jennifer B. Bergner5https://orcid.org/0000-0002-8716-0482David J. Wilner6https://orcid.org/0000-0003-1526-7587Jane Huang7https://orcid.org/0000-0001-6947-6072Viviana V. Guzmán8https://orcid.org/0000-0003-4784-3040L. Ilsedore Cleeves9https://orcid.org/0000-0003-2076-8001C enter for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA ; carlos.munoz_romero@cfa.harvard.eduC enter for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA ; carlos.munoz_romero@cfa.harvard.eduC enter for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA ; carlos.munoz_romero@cfa.harvard.eduC enter for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA ; carlos.munoz_romero@cfa.harvard.edu; Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology , Cambridge, MA 02139, USADepartment of Astronomy, Graduate School of Science, University of Tokyo , Tokyo 113-0033, JapanDepartment of the Geophysical Sciences, University of Chicago , Chicago, IL 60637, USAC enter for Astrophysics ∣ Harvard & Smithsonian , Cambridge, MA 02138, USA ; carlos.munoz_romero@cfa.harvard.eduDepartment of Astronomy, University of Michigan , 323 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USAInstituto de Astrofísica, Pontificia Universidad Católica de Chile , Avenida Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile; Núcleo Milenio de Formación Planetaria (NPF) , Gran Bretaña 1111, Valparaiso, ChileAstronomy Department, University of Virginia , Charlottesville, VA 22904, USADeuterium fractionation provides a window into the thermal history of volatiles in the solar system and protoplanetary disks. While evidence of active molecular deuteration has been observed toward a handful of disks, it remains unclear whether this chemistry affects the composition of forming planetesimals due to limited observational constraints on the radial and vertical distribution of deuterated molecules. To shed light on this question, we introduce new Atacama Large Millimeter/submillimeter Array observations of DCO ^+ and DCN J = 2–1 at an angular resolution of 0.″5 (30 au) and combine them with archival data of higher energy transitions toward the protoplanetary disk around TW Hya. We carry out a radial excitation analysis assuming both LTE and non-LTE to localize the physical conditions traced by DCO ^+ and DCN emission in the disk, thus assessing deuterium fractionation efficiencies and pathways at different disk locations. We find similar disk-averaged column densities of 1.9 × 10 ^12 and 9.8 × 10 ^11 cm ^−2 for DCO ^+ and DCN, with typical kinetic temperatures for both molecules of 20–30 K, indicating a common origin near the comet- and planet-forming midplane. The observed DCO ^+ /DCN abundance ratio, combined with recent modeling results, provide tentative evidence of a gas-phase C/O enhancement within <40 au. Observations of DCO ^+ and DCN in other disks, as well as HCN and HCO ^+ , will be necessary to place the trends exhibited by TW Hya in context, and fully constrain the main deuteration mechanisms in disks.https://doi.org/10.3847/1538-4357/aca765Protoplanetary disksPlanet formationIsotopic abundancesAstrochemistry |
| spellingShingle | Carlos E. Romero-Mirza Karin I. Öberg Charles J. Law Richard Teague Yuri Aikawa Jennifer B. Bergner David J. Wilner Jane Huang Viviana V. Guzmán L. Ilsedore Cleeves Cold Deuterium Fractionation in the Nearest Planet-forming Disk The Astrophysical Journal Protoplanetary disks Planet formation Isotopic abundances Astrochemistry |
| title | Cold Deuterium Fractionation in the Nearest Planet-forming Disk |
| title_full | Cold Deuterium Fractionation in the Nearest Planet-forming Disk |
| title_fullStr | Cold Deuterium Fractionation in the Nearest Planet-forming Disk |
| title_full_unstemmed | Cold Deuterium Fractionation in the Nearest Planet-forming Disk |
| title_short | Cold Deuterium Fractionation in the Nearest Planet-forming Disk |
| title_sort | cold deuterium fractionation in the nearest planet forming disk |
| topic | Protoplanetary disks Planet formation Isotopic abundances Astrochemistry |
| url | https://doi.org/10.3847/1538-4357/aca765 |
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