Researchers used IRAM 30m telescope (a radio telescope) for prestellar cores; L1448, B213‑C6.
The prestellar core is a very cold, dense region of gas and dust in a molecular cloud before a star has formed inside it.
The replacement of hydrogen by deuterium begins before a star is formed, during the cold, dense phase of molecular cloud evolution.
They used the EMIR receiver with the FTS backend (Fourier Transform Spectrometer) to record wide-band spectra and searched for lines corresponding to CH₃OH, CH₂DOH, and CH₃OD.
The calculation of the column densities of CH2DOH and CH3OD was carried out under the assumption of local thermal equilibrium (LTE). The equation converts the measured line intensity to how many molecules are in that energy level per unit area.
The D/H ratio is generally higher in the methyl group (CH₂DOH) than in the hydroxyl group (CH₃OD) in cold star-forming regions.
When the prestellar core is very cold, more deuterium atoms replace hydrogen in molecules like methanol that form in icy dust grains. But as the temperature rises above about 15 K, this deuteration process becomes less efficient, so the D/H ratios become lower. Colder conditions lead to higher deuteration, while slightly warmer conditions reduce it.
Methanol and its deuterated versions form mainly through successive hydrogenation and deuteration of CO molecules on icy dust grains in extremely cold prestellar cores.
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