Detection And Prebiotic Chemistry of Possible Glycine Precursor Molecule Methylenimine Towards The Hot Molecular Core G10.47+0.03

Amino acids are essential for the synthesis of protein. Amino acids contain both amine (R−NH₂) and carboxylic acid (R−COOH) functional groups, which help to understand the possible formation mechanism of life in the universe.

Among the 20 types of amino acids, glycine (NH₂CH₂COOH) is known as the simplest non-essential amino acid. In the last 40 years, all surveys of NH₂CH₂COOH in the interstellar medium, especially in the star-formation regions, have failed at the millimeter and sub-millimeter wavelengths. We aimed to identify the possible precursors of NH₂CH₂COOH, because it is highly challenging to identify NH₂CH₂COOH in the interstellar medium.

Many laboratory experiments have suggested that methylenimine (CH₂NH) plays a key role as a possible precursor of NH₂CH₂COOH in the star-formation regions via the Strecker synthesis reaction. After spectral analysis using the local thermodynamic equilibrium (LTE) model, we successfully identified the rotational emission lines of CH₂NH towards the hot molecular core G10.47+0.03 using the Atacama Compact Array (ACA). The estimated column density of CH₂NH towards G10.47+0.03 is (3.40±0.2)×10¹⁵ cm⁻² with a rotational temperature of 218.70±20 K, which is estimated from the rotational diagram.

The fractional abundance of CH₂NH with respect to H2 towards G10.47+0.03 is 2.61×10⁻⁸. We found that the derived abundance of CH₂NH agree fairly well with the existing two-phase warm-up chemical modelling abundance value of CH₂NH. We discuss the possible formation pathways of CH₂NH within the context of hot molecular cores, and we find that CH₂NH is likely mainly formed via neutral-neutral gas-phase reactions of CH₃ and NH radicals towards G10.47+0.03.

Proposed possible formation mechanism of CH₂NH and NH₂CH₂COOH. In the chemical diagram, the black/grey dumbbell indicates the carbon (C) atom, the white dumbbell indicates the hydrogen (H) atom, the blue dumbbell indicates the nitrogen (N) atom, and the red dumbbell indicates the oxygen (O) atom. In the chemical reaction, “H₂O” represents the hydrolysis process. References: (A) Woon et al. (2002); Theule et al. (2011); (B) Danger et al. (2011); (C) Alonso et al. (2018). — astro-ph.GA

Arijit Manna, Sabyasachi Pal

Comments: Accepted for publication in International Journal of Astrobiology. arXiv admin note: text overlap with arXiv:2402.16798
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Cite as: arXiv:2404.12212 [astro-ph.GA] (or arXiv:2404.12212v1 [astro-ph.GA] for this version)
Submission history
From: Arijit Manna
[v1] Thu, 18 Apr 2024 14:17:21 UTC (562 KB)
https://arxiv.org/abs/2404.12212
Astrobiology, Astrochemistry,