Issue |
A&A
Volume 694, February 2025
|
|
---|---|---|
Article Number | A147 | |
Number of page(s) | 29 | |
Section | Planets, planetary systems, and small bodies | |
DOI | https://doi.org/10.1051/0004-6361/202452152 | |
Published online | 07 February 2025 |
MINDS
The influence of outer dust disc structure on the volatile delivery to the inner disc
1
Institute of Astronomy,
Celestijnenlaan 200D,
3001
Leuven,
Belgium
2
Leiden Observatory, Leiden University,
2300 RA
Leiden,
The Netherlands
3
Max-Planck Institut für Extraterrestrische Physik (MPE),
Giessen-bachstr. 1,
85748
Garching,
Germany
4
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale,
91405
Orsay,
France
5
Max-Planck-Institut für Astronomie (MPIA),
Königstuhl 17,
69117
Heidelberg,
Germany
6
Kapteyn Astronomical Institute, Rijksuniversiteit Groningen,
Postbus 800,
9700AV
Groningen,
The Netherlands
7
Dept. of Astrophysics, University of Vienna,
Türkenschanzstr. 17,
1180
Vienna,
Austria
8
ETH Zürich, Institute for Particle Physics and Astrophysics,
Wolfgang-Pauli-Str. 27,
8093
Zürich,
Switzerland
9
Centro de Astrobiología (CAB), CSIC-INTA, ESAC Campus,
Camino Bajo del Castillo s/n,
28692
Villanueva de la Cañada, Madrid,
Spain
10
INAF -– Osservatorio Astronomico di Capodimonte,
Salita Moiariello 16,
80131
Napoli,
Italy
11
Dublin Institute for Advanced Studies,
31 Fitzwilliam Place,
D02 XF86
Dublin,
Ireland
12
Department of Astrophysics/IMAPP, Radboud University,
PO Box 9010,
6500 GL
Nijmegen,
The Netherlands
13
SRON Netherlands Institute for Space Research,
Niels Bohrweg 4,
2333 CA
Leiden,
The Netherlands
14
Space Research Institute, Austrian Academy of Sciences,
Schmiedlstr. 6,
A-8042,
Graz,
Austria
15
TU Graz, Fakultät für Mathematik, Physik und Geodäsie,
Petersgasse 16,
8010
Graz,
Austria
16
Niels Bohr Institute, University of Copenhagen,
NBB BA2, Jagtvej 155A,
2200
Copenhagen,
Denmark
★ Corresponding author; danny.gasman@kuleuven.be
Received:
6
September
2024
Accepted:
20
December
2024
Context. The Atacama Large Millimeter/submillimeter Array (ALMA) has revealed that the millimetre dust structures of protoplanetary discs are extremely diverse, ranging from small and compact dust discs to large discs with multiple rings and gaps. It has been proposed that the strength of H2O emission in the inner disc particularly depends on the influx of icy pebbles from the outer disc, a process that would correlate with the outer dust disc radius, and that could be prevented by pressure bumps. Additionally, the dust disc structure should also influence the emission of other gas species in the inner disc. Since terrestrial planets likely form in the inner disc regions, understanding their composition is of interest.
Aims. This work aims to assess the influence of pressure bumps on the inner disc’s molecular reservoirs. The presence of a dust gap, and potentially giant planet formation farther out in the disc, may influence the composition of the inner disc, and thus the building blocks of terrestrial planets.
Methods. Using the improved sensitivity and spectral resolution of the Mid-InfraRed Instrument’s (MIRI) Medium Resolution Spectrometer (MRS) on the James Webb Space Telescope (JWST) compared to Spitzer, we compared the observational emission properties of H2O, HCN, C2H2, and CO2 with the outer dust disc structure from ALMA observations, in eight discs with confirmed gaps in ALMA observations, and two discs with gaps of tens of astronomical units in width, around stars with M⋆ ≥ 0.45 M⊙ . We used new visibility plane fits of the ALMA data to determine the outer dust disc radius and identify substructures in the discs.
Results. We find that the presence of a dust gap does not necessarily result in weak H2O emission. Furthermore, the relative lack of colder H2O-emission seems to go hand in hand with elevated emission from carbon-bearing species. Of the discs that show significant substructure within the CO and CH4 snowlines, most show detectable emission from the carbon-bearing species. The discs with cavities and extremely wide gaps appear to behave as a somewhat separate group, with stronger cold H2O emission and weak warm H2O emission.
Conclusions. We conclude that fully blocking radial dust drift from the outer disc seems difficult to achieve, even for discs with very wide gaps or cavities, which can still show significant cold H2O emission. However, there does seem to be a dichotomy between discs that show a strong cold H2O excess and ones that show strong emission from HCN and C2H2. Better constraints on the influence of the outer dust disc structure and inner disc composition require more information on substructure formation timescales and disc ages, along with the importance of trapping of (hyper)volatiles like CO and CO2 into more strongly bound ices like H2O and chemical transformation of CO into less volatile species.
Key words: astrochemistry / protoplanetary disks / stars: variables: T Tauri, Herbig Ae/Be / infrared: planetary systems / submillimeter: planetary systems
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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