An exceptional prevalence of simple gaseous hydrocarbons—encompassing benzene, triacetylene, diacetylene, acetylene, methane, and methyl radical—has been identified by astronomers operating the NASA/ESA/CSA James Webb Space Telescope within the heavily shielded core of the ultra-luminous infrared galaxy IRAS 07251-0248, a celestial entity situated in the Monoceros constellation.
Hydrocarbons are instrumental in dictating the chemical composition of the interstellar medium; however, their proliferation and connection to carbonaceous particulates and polycyclic aromatic hydrocarbons currently lack definitive observational corroboration. García-Bernete et al. present findings from Webb’s infrared investigations of the local ultra-luminous infrared galaxy (ULIRG) known as IRAS 07251-0248, which documented the first extragalactic observation of minor gaseous hydrocarbons. Image courtesy of García-Bernete et al., with the digital object identifier 10.1038/s41550-025-02750-0.
The central region of the galaxy designated IRAS 07251-0248, also identified as 2MASS J07273756-0254540, is concealed by substantial accumulations of interstellar gas and dust.
This intervening matter effectively absorbs the preponderant portion of radiation emanating from the central supermassive black hole, rendering it exceedingly challenging to scrutinize using conventional telescopic instrumentation.
Nevertheless, the electromagnetic spectrum in the infrared range possesses the inherent capability to permeate such dusty veils, thereby furnishing invaluable insights into these obscured environments and illuminating the principal chemical processes operative within this exceedingly dusty galactic nucleus.
Dr. Ismael García Bernete, along with his research associates, employed spectroscopic analyses derived from Webb’s NIRSpec and MIRI instruments, spanning the wavelength continuum from 3 to 28 microns.
These analytical techniques facilitate the identification of molecular signatures originating from gaseous compounds, as well as characteristic spectral features associated with ices and dust particulates.
Leveraging this acquired data, the astronomical team was adept at characterizing the relative concentrations and thermal conditions of a multitude of chemical constituents present within the nucleus of this enshrouded galaxy.
The observational results yielded a remarkably abundant collection of simple organic molecules, including but not limited to benzene, methane, acetylene, diacetylene, and triacetylene. Furthermore, a significant discovery was the detection of the methyl radical, marking its initial observation beyond the confines of the Milky Way’s galactic boundary.
In addition to the molecular species identified in the gaseous state, a substantial quantity of solid molecular materials was also ascertained, such as carbonaceous dust grains and frozen water ice.
“We encountered an unexpected level of chemical intricacy, with abundances significantly exceeding those predicted by prevailing theoretical models,” stated Dr. García Bernete, an astrophysicist affiliated with the Centro de Astrobiología.
“This observation implies the presence of a persistent carbon source within these galactic nuclei that is continuously supplying this rich molecular network.”
“These specific molecules may fulfill a pivotal role as foundational constituents for more complex organic chemistry, holding considerable interest for processes relevant to the genesis of life.”
“While simple organic molecules are not components of living organisms, they could potentially contribute significantly to prebiotic chemistry, representing a crucial intermediary stage in the formation of amino acids and nucleotides,” commented Professor Dimitra Rigopoulou from the University of Oxford.
The research outcomes were disseminated this week within the esteemed journal Nature Astronomy.
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I. García-Bernete et al. Abundant hydrocarbons in a buried galactic nucleus with signs of carbonaceous grain and polycyclic aromatic hydrocarbon processing. Nat Astron, published online February 8, 2026; doi: 10.1038/s41550-025-02750-0
