Simple molecules and complex chemistry in a protoplanetary disk

A JWST investigation of the highly inclined disk d216-0939

¹ Analytical Mineralogy Group, Institute of Geosciences, Friedrich Schiller University Jena, Jena, Germany
² Max Planck Institute for Astronomy, Heidelberg, Germany
³ Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands
⁴ Institute of Theoretical Physics and Astrophysics, Kiel University, Leibnizstr. 15, 24118, Kiel, Germany
⁵ National Astronomical Observatory of Japan, Tokyo, Japan

^★ Corresponding author: alexey.potapov@uni-jena.de

Received: 10 December 2024
Accepted: 20 February 2025

Abstract

Context. While the number of detected molecules, particularly complex organic molecules, in the solid state in astrophysical environments is still rather limited, laboratory experiments and astrochemical models predict many potential candidates. Detection of molecules in protoplanetary disks provides a bridge between the chemical evolution of the interstellar medium and the chemistry of planets and their atmospheres.

Aims. The excellent spectral sensitivity, broad wavelength coverage, and high spatial resolution of the James Webb Space Telescope (JWST) allows us to make progress in exploring chemical compositions of various astrophysical environments, including planet-forming disks. They are a prerequisite for probing the disk content by means of sensitive absorption studies.

Methods. In this paper we present the initial results of the JWST Cycle 1 GO programme 1741 on d216-0939, a highly inclined TTauri disk located in the outskirts of the Orion Nebula Cluster. We utilised the NIRSpec and MIRI integral field unit spectrographs to cover its spectrum from 1.7 to 28 μm.

Results. The spectra of the d216-0939 disk show clear absorption signatures of amorphous silicates and ices. We unambiguously detected the solid-state features of H₂O, CO₂, ¹³CO₂, CO, OCN⁻, and tentatively OCS ices, species that had also been detected recently in other circumstellar disks. For the first time in disks, we provide unique detections of ices carrying NH₄⁺ and the complex organic molecule ammonium carbamate (NH₄⁺NH₂COO⁻).

Conclusions. The latter detections speak for a very efficient NH₃ chemistry in the disk. We also show the very important role of scattering in the analysis of observational spectra of highly inclined disks.