Webb Detects Surprising Richness of Hydrocarbons in Obscured Core of Close by Extremely-Luminous Galaxy

Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have uncovered an unprecedented richness of small gas-phase hydrocarbons — comparable to benzene, triacetylene, diacetylene, acetylene, methane and methyl radical — within the deeply obscured nucleus of the ultra-luminous infrared galaxy IRAS 07251-0248, which is situated within the constellation of Monoceros.

Hydrocarbons play a key function in shaping the chemistry of the interstellar medium, however their enrichment and relation with carbonaceous grains and polycyclic fragrant hydrocarbons nonetheless lack clear observational constraints. García-Bernete et al. report on the Webb infrared observations of the native ultra-luminous infrared galaxy (ULIRG) IRAS 07251-0248, which revealed the extragalactic detection of small gas-phase hydrocarbons. Image credit score: García-Bernete et al., doi: 10.1038/s41550-025-02750-0.

The nucleus of IRAS 07251-0248 (also called 2MASS J07273756-0254540) is hidden behind huge quantities of gasoline and dirt.

This materials absorbs many of the radiation emitted by the central supermassive black gap, making it extraordinarily troublesome to review with typical telescopes.

However, the infrared wavelength vary penetrates the mud and gives distinctive details about these areas, revealing the dominant chemical processes on this extraordinarily dusty nucleus.

Dr. Ismael García Bernete and his colleagues used spectroscopic observations from Webb’s NIRSpec and MIRI devices overlaying the 3-28 micron wavelength vary.

These observations enable the detection of chemical signatures from gas-phase molecules, in addition to options from ices and dirt grains.

Thanks to those information, the astronomers have been capable of characterize the abundance and temperature of quite a few chemical species within the nucleus of this buried galaxy.

The observations revealed an awfully wealthy stock of small natural molecules, together with benzene, methane, acetylene, diacetylene, and triacetylene, and, detected for the primary time exterior the Milky Way, the methyl radical.

In addition to gas-phase molecules, a big abundance of stable molecular supplies was discovered, comparable to carbonaceous grains and water ices.

“We found an unexpected chemical complexity, with abundances far higher than predicted by current theoretical models,” mentioned Dr. García Bernete, an astronomer on the Centro de Astrobiología.

“This indicates that there must be a continuous source of carbon in these galactic nuclei fueling this rich chemical network.”

“These molecules could play a key role as fundamental building blocks for complex organic chemistry, of interest for processes relevant to life.”

“Although small organic molecules are not found in living cells, they could play a vital role in prebiotic chemistry representing an important step towards the formation of amino acids and nucleotides,” mentioned University of Oxford’s Professor Dimitra Rigopoulou.

The findings have been printed this week within the journal Nature Astronomy.

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I. García-Bernete et al. Abundant hydrocarbons in a buried galactic nucleus with indicators of carbonaceous grain and polycyclic fragrant hydrocarbon processing. Nat Astron, printed on-line February 8, 2026; doi: 10.1038/s41550-025-02750-0