First Detection Of Ethylene Oxide And Acetaldehyde In Hot Core G358.93−0.03 MM1: Tracing Prebiotic Oxygen Chemistry

Ethylene oxide (c-C₂H₄O) and its isomer, acetaldehyde (CH₃CHO), are important complex organic molecules owing to their potential role in the formation of amino acids (R-CH(NH₂)-COOH) in ISM.

The detection of c-C₂H₄O in hot molecular cores suggests that the possible existence of larger ring-shaped molecules containing more than three carbon atoms, such as furan (c-C₄H₄O), which shares structural similarities with ribose (C₅H₁₀O₅), the sugar component of DNA.

In this study, we report the first detection of the rotational emission lines of c-C₂H₄O and CH₃CHO towards the hot molecular core G358.93−0.03 MM1, based on observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) in band 7. The fractional abundances of c-C₂H₄O and CH₃CHO relative to H₂ are (2.1±0.2)×10⁻⁹ and (7.1±0.9)×10⁻⁹, respectively. The column density ratio between CH₃CHO and c-C₂H₄O is 3.4±0.7.

A Pearson correlation heat map reveals strong positive correlations (r > 0.5) between the abundances and excitation temperatures of c-C₂H₄O and CH₃CHO, suggesting a possible chemical connection between those two molecules. To investigate this further, we conducted a two-phase warm-up chemical model using the gas-grain chemical code UCLCHEM.

A comparison between our derived abundances and the predictions from our chemical model and existence model demonstrates good agreement within factors of 0.73 and 0.74, respectively. We propose that c-C₂H₄O may form in G358.93−0.03 MM1 via the grain surface reaction between C₂H₄ and O, but CH₃CHO may be produced through the surface reaction between CH₃ and HCO.

Schematic diagram and molecular distribution of the hot molecular core. — astro-ph.GA

Arijit Manna, Sabyasachi Pal

Comments: Published in New Astronomy
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph); Space Physics (physics.space-ph)
Cite as: arXiv:2509.03382 [astro-ph.GA] (or arXiv:2509.03382v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2509.03382
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Journal reference: New Astron, 122, 102465 (2026)
Related DOI:
https://doi.org/10.1016/j.newast.2025.102465
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Submission history
From: Arijit Manna
[v1] Wed, 3 Sep 2025 14:58:28 UTC (1,348 KB)
https://arxiv.org/abs/2509.03382

Astrobiology, Astrochemistry,