Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have identified an extraordinary presence of small gas-phase hydrocarbons—such as benzene, triacetylene, diacetylene, acetylene, methane, and methyl radicals—within the concealed core of the ultra-bright infrared galaxy IRAS 07251-0248.
Hydrocarbons are influential in shaping the chemistry of the interstellar medium. However, definite observational constraints on their enrichment and relationship with carbonaceous particles and polycyclic aromatic hydrocarbons remain elusive. García Bernete et al. report Webb infrared observations of the Local Ultraluminous Infrared Galaxy (ULIRG) IRAS 07251-0248, revealing extragalactic detections of small gas-phase hydrocarbons. Image credit: García-Bernete et al., doi: 10.1038/s41550-025-02750-0.
The core of IRAS 07251-0248 (also known as 2MASS J07273756-0254540) is obscured by significant amounts of gas and dust.
This dense material absorbs most radiation emitted by the central supermassive black hole, complicating studies with traditional telescopes.
However, the infrared spectrum can penetrate this dust, providing unique insights about these regions and illuminating vital chemical processes in this heavily obscured core.
Dr. Ismael García Bernete and his team employed spectroscopic observations using Webb’s NIRSpec and MIRI instruments, covering wavelengths from 3 to 28 microns.
These observations reveal chemical signatures of gas-phase molecules alongside signatures from ice and dust particles.
These data empowered astronomers to characterize the abundance and temperature of various chemical species within the core of this concealed galaxy.
Remarkably, they discovered an exceptionally high abundance of small organic molecules such as benzene, methane, acetylene, diacetylene, and triacetylene—the first such detections outside our Milky Way, including the methyl radical.
Additionally, substantial amounts of solid molecular materials, including carbonaceous particles and water ice, were identified.
“We uncovered unexpected chemical complexity, showcasing abundances far exceeding current theoretical models,” stated Dr. García Bernete, an astronomer at the Astrobiology Center.
“This suggests a continuous source of carbon within these galactic nuclei, fueling this rich chemical network.”
“These molecules may serve as vital building blocks for complex organic chemistry, relevant to processes that pertain to life.”
Professor Dimitra Rigopoulou from the University of Oxford remarked, “Small organic molecules may not exist in living cells, yet they could play a pivotal role in prebiotic chemistry—a crucial step toward forming amino acids and nucleotides.”
These findings were published in a recent issue of Nature Astronomy.
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I. Garcia-Bernete et al. Abundant hydrocarbons within buried galactic nuclei with evidence of processing of carbonaceous particles and polycyclic aromatic hydrocarbons. Nat Astron, published online on February 8, 2026. doi: 10.1038/s41550-025-02750-0
Source: www.sci.news
