MINDS. Hydrocarbons detected by JWST/MIRI in the inner disk of Sz28 consistent with a high C/O gas-phase chemistry
Journal
Date Issued
2024
Author(s)
Jayatee Kanwar
•
Inga Kamp
•
Hyerin Jang
•
L. B. F. M. Waters
•
Ewine F. van Dishoeck
•
Valentin Christiaens
•
Aditya M. Arabhavi
•
Thomas Henning
•
Manuel Güdel
•
Peter Woitke
•
Olivier Absil
•
David Barrado
•
•
Adrian M. Glauser
•
Fred Lahuis
•
Silvia Scheithauer
•
Bart Vandenbussche
•
Danny Gasman
•
Sierra L. Grant
•
Nicolas T. Kurtovic
•
Giulia Perotti
•
Benoît Tabone
•
Milou Temmink
Abstract
With the advent of JWST, we acquire unprecedented insights into the physical
and chemical structure of the inner regions of planet-forming disks where
terrestrial planet formation occurs. The very low-mass stars (VLMS) are known
to have a high occurrence rate of the terrestrial planets around them.
Exploring the chemical composition of the gas in these inner regions of the
disks can aid a better understanding of the connection between planet-forming
disks and planets. The MIRI mid-Infrared Disk Survey (MINDS) project is a large
JWST Guaranteed Time program to characterize the chemistry and physical state
of planet-forming and debris disks. We use the JWST-MIRI/MRS spectrum to
investigate the gas and dust composition of the planet-forming disk around the
very low-mass star Sz28 (M5.5, 0.12\,M$_{\odot}$). We use the dust-fitting tool
(DuCK) to determine the dust continuum and to get constraints on the dust
composition and grain sizes. We use 0D slab models to identify and fit the
molecular spectral features, yielding estimates on the temperature, column
density and the emitting area. To test our understanding of the chemistry in
the disks around VLMS, we employ the thermo-chemical disk model {P{\tiny
RO}D{\tiny I}M{\tiny O}} and investigate the reservoirs of the detected
hydrocarbons. We explore how the C/O ratio affects the inner disk chemistry.
JWST reveals a plethora of hydrocarbons, including \ce{CH3}, \ce{CH4},
\ce{C2H2}, \ce{^{13}CCH2}, \ce{C2H6}, \ce{C3H4}, \ce{C4H2} and \ce{C6H6}
suggesting a disk with a gaseous C/O\,>\,1. Additionally, we detect \ce{CO2},
\ce{^{13}CO2}, \ce{HCN}, and \ce{HC3N}. \ce{H2O} and OH are absent in the
spectrum. We do not detect PAHs. Photospheric stellar absorption lines of
\ce{H2O} and \ce{CO} are identified. Notably, our radiation thermo-chemical
disk models are able to produce these detected hydrocarbons in the surface
layers of the disk when the ...
Volume
689
Start page
A231
Issn Identifier
0004-6361
Rights
open.access
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