Hunt for complex cyanides in protostellar ices with JWST: Tentative detection of CH${}_3$CN and C${}_2$H${}_5$CN

Abstract

Nitrogen-bearing complex organic molecules have been commonly detected in the gas phase but not yet in interstellar ices. This has led to the long-standing question of whether these molecules form in the gas phase or in ices. $\text{James Webb}$ Space Telescope ($\text{JWST}$) offers the sensitivity, spectral resolution, and wavelength coverage needed to detect them in ices and investigate whether their abundance ratios are similar in gas and ice. We report the first tentative detection of CH${}_3$CN, C${}_2$H${}_5$CN, and the simple molecule, N${}_2$O, based on the CN-stretch band in interstellar ices toward three (HOPS 153, HOPS 370, and IRAS 20126+4104) out of the five protostellar systems observed as part of the Investigating Protostellar Accretion (IPA) GO program with $\text{JWST}$-NIRSpec. We also provide upper limits for the two other sources with smaller luminosities in the sample. We detect OCN${}^{-}$ in the ices of all sources with typical CH${}_3$CN/OCN${}^{-}$ ratios of around 1. Ice and gas column density ratios of the nitrogen-bearing species with respect to each other are better matched than those with respect to methanol, which are a factor of $\sim 5$ larger in the ices than the gas. We attribute the elevated ice column densities with respect to methanol to the difference in snowline locations of nitrogen-bearing molecules and of methanol, biasing the gas-phase observations toward fewer nitrogen-bearing molecules. Moreover, we find tentative evidence for enhancement of OCN${}^{-}$, CH${}_3$CN, and C${}_2$H${}_5$CN in warmer ices, although formation of these molecules likely starts along with methanol in the cold prestellar phase. Future surveys combining NIRSpec and MIRI, and additional laboratory spectroscopic measurements of C${}_2$H${}_5$CN ice, are necessary for robust detection and conclusions on the formation history of complex cyanides.

Accepted for publication in A&A

References in corpus (48)

• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• The ALMA Protostellar Interferometric Line Survey (PILS): First results from an unbiased submillimeter wavelength line survey of the Class 0 protostellar binary IRAS 16293-2422 with ALMA
• An Ice Age JWST inventory of dense molecular cloud ices
• The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. A Statistical Characterization of Class 0 and I Protostellar Disks
• Formation of complex organic molecules in cold objects: the role of gas phase reactions
• The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects II: CO2
• The cometary composition of a protoplanetary disk as revealed by complex cyanides
• Complex organic molecules in protoplanetary disks
• Molecular Evolution and Star Formation: From Prestellar Cores to Protostellar Cores
• The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope III. Integral-field spectroscopy
• In-orbit Performance of the Near-Infrared Spectrograph NIRSpec on the James Webb Space Telescope
• Formation of complex organic molecules in hot molecular cores through nondiffusive grain-surface and ice-mantle chemistry
• A non-energetic mechanism for glycine formation in the interstellar medium
• Sensitivity analysis of grain surface chemistry to binding energies of ice species
• The Perseus ALMA Chemistry Survey (PEACHES). I. The Complex Organic Molecules in Perseus Embedded Protostars
• Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk
• CORINOS I: JWST/MIRI Spectroscopy and Imaging of a Class 0 protostar IRAS 15398-3359
• Formation of Glycerol through Hydrogenation of CO ice under Prestellar Core Conditions
• Complex organic molecules in low-mass protostars on solar system scales -- I. Oxygen-bearing species
• Evolutionary study of complex organic molecules in high-mass star-forming regions
• Complex organic molecules in low-mass protostars on Solar System scales -- II. Nitrogen-bearing species
• A major asymmetric ice trap in a planet-forming disk: III. First detection of dimethyl ether
• Gas-phase formation of acetaldehyde: review and new theoretical computations
• LIDA - The Leiden Ice Database for Astrochemistry
• The diverse chemistry of protoplanetary disks as revealed by JWST
• Investigating Protostellar Accretion-Driven Outflows Across the Mass Spectrum: JWST NIRSpec IFU 3-5~$\mu$m Spectral Mapping of Five Young Protostars
• Survey of Ices toward Massive Young Stellar Objects: I. OCS, CO, OCN${}^{-}$, and CH${}_3$OH
• N-bearing complex organics toward high-mass protostars: Constant ratios pointing to formation in similar pre-stellar conditions across a large mass range
• Formation of interstellar propanal and 1-propanol ice: a pathway involving solid-state CO hydrogenation
• CoCCoA: Complex Chemistry in hot Cores with ALMA. Selected oxygen-bearing species
• The role of C/O in nitrile astrochemistry in PDRs and planet-forming disks
• First experimental confirmation of the CH3O + H2CO -> CH3OH + HCO reaction: expanding the CH3OH formation mechanism in interstellar ices
• An overview of desorption parameters of Volatile and Complex Organic Molecules: A systematic dig on experimental literature
• Influence of grain growth on CO2 ice spectroscopic profiles : Modelling for dense cores and disks
• JWST observations of ${}^{13}$CO${}_2$ ice: Tracing the chemical environment and thermal history of ices in protostellar envelopes
• Formation of complex organic molecules in molecular clouds: acetaldehyde, vinyl alcohol, ketene, and ethanol via the "energetic" processing of C${}_2$H${}_2$ ice
• Digging into the Interior of Hot Cores with ALMA (DIHCA). III: The Chemical Link between NH${}_2$CHO, HNCO, and H${}_2$CO
• Infrared spectra of complex organic molecules in astronomically relevant ice mixtures. V. Methyl cyanide (acetonitrile)
• Investigation of HNCO isomers formation in ice mantles by UV and thermal processing: an experimental approach
• The Physical Properties of the SVS 13 Protobinary System: Two Circumstellar Disks and a Spiraling Circumbinary Disk in the Making
• Methanol deuteration in high-mass protostars
• The hunt for formamide in interstellar ices: A toolkit of laboratory infrared spectra in astronomically relevant ice mixtures and comparisons to ISO, Spitzer, and JWST observations
• Fitting infrared ice spectra with genetic modelling algorithms. Presenting the ENIIGMA fitting tool
• Models of Rotating Infall for the B335 Protostar
• Evidence for ubiquitous carbon grain destruction in hot protostellar envelopes

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• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Simple molecules and complex chemistry in a protoplanetary disk: A JWST investigation of the highly inclined disk d216-0939
• Interstellar Chemistry of CN Radicals on Ices: The formation of CH3CN and CH3NC and potential connection to acetamide
• CoCCoA: Complex Chemistry in hot Cores with ALMA. The chemical evolution of acetone from ice to gas
• Toward Unraveling Cyanopolyyne Surface Chemistry: A Preview on Isolated Systems From HC_{3}N to Ethyl Cyanide and Propylamine
• JOYS: Linking the molecular ice and gas-phase composition towards the high-mass hot core IRAS 18089-1732
• Quantifying the temperature-dependent yields of N${}_2$ and N${}_2$H${}_4$ formation in vacuum-ultraviolet-irradiated NH${}_3$ ice