Astrochemistry

First Detection Of CH3OD In Prestellar Cores

By Keith Cowing

Status Report

astro-ph.E

November 10, 2025

Filed under astrochemistry, astronomy, B213-C6, ices, imaging, Interstellar, organic chemistry, prestellar core L1448, Spectroscopy

First Detection Of CH3OD In Prestellar Cores — D/H ratios for CH₂DOH (left panel) and CH₃OD (right panel) across the star-forming sequence. The spread per source type was calculated using all column densities listed in Table A. The black circle denotes the average of the values. The values of CH₂DOH have been statistically corrected. Violin plots demonstrate the density distribution of the data: the wider the area of the violin, the more data points are around this value; narrow regions show that data are sparse at this value. — astro-ph.GA

The isotopic ratios of deuterated methanol derived around protostars are commonly used to infer the physical conditions under which they formed in the earlier prestellar stage.

However, there is a discrepancy in the ratio of the singly deuterated methanol isotopologues, CH₂DOH/CH₃OD, between low- and high-mass protostars, which puts into question whether prestellar isotopic ratios are generally preserved during the star- and planet-forming process. Resolving this puzzle is only made harder by the complete lack of data on this ratio in the prestellar stage.

This work presents observations with the IRAM 30m telescope that securely detect CH₃OD in the prestellar core L1448 in Perseus and tentatively in B213-C6 in Taurus. This work constrains the ratio of CH₂DOH/CH₃OD and the D/H ratios for both singly deuterated methanol isotopologues for the first time at the prestellar stage.

Column densities calculated under the assumption of local thermal equilibrium lead to a CH₂DOH/CH₃OD ratio of 2.8-8.5 in L1448 and ≤ 5.7 in B213-C6. The values are marginally consistent with the statistically expected ratio of 3, but most assumptions put the values in an elevated range in line with values found around low-mass protostars.

The D/H ratio in CH₂DOH is between 3.6% and 6.8% in L1448 and in the range of 2.4-5.8% in B213-C6. The D/H ratio derived for CH₃OD is lower, namely 1.4-4.4% in L1448 and ≤ 3.8% in B213-C6.

Beatrice M. Kulterer, Asunción Fuente, Maria N. Drozdovskaya, Silvia Spezzano, Gisela Esplugues, David Navarro-Almaida, Marina Rodríguez Baras, Angèle Taillard, Karin Öberg

Comments: Accepted for publication in ApJ 22 pages, 6 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2511.03581 [astro-ph.GA] (or arXiv:2511.03581v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2511.03581
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Submission history
From: Beatrice Kulterer
[v1] Wed, 5 Nov 2025 16:02:40 UTC (1,502 KB)
https://arxiv.org/abs/2511.03581

Astrobiology, Astrochemistry,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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