PAH Molecules Detected in Disk Around Young Sun-like Star

In December 2025, astronomers gained new insights into planet formation after detecting complex hydrocarbon molecules in the circumstellar disk of a young Sun-like star, T Chamaeleontis, offering clues to early planetary evolution and prebiotic chemistry.

Key Points

Major Discovery: Complex hydrocarbons known as polycyclic aromatic hydrocarbons (PAHs) have been detected in the circumstellar disk around T Chamaeleontis, located about 350 light-years from Earth.
Research Institution: The study was conducted by scientists from the Indian Institute of Astrophysics (IIA), an autonomous institute under India’s Department of Science and Technology.
Telescope & Instrument: Researchers analysed archival observations from James Webb Space Telescope (JWST) using its Mid-Infrared Instrument (MIRI).
About PAHs: PAHs are flat, carbon-rich molecules considered key precursors to complex organic chemistry and potential building blocks of life.
Disk Structure Insight: T Chamaeleontis has a circumstellar disk with a large gap, likely carved out by a forming planet, indicating active planet formation.
Unexpected Detection: PAHs are usually hard to detect around low-mass stars because dense inner disks block ultraviolet (UV) radiation; however, a high accretion event caused partial collapse of the disk’s inner wall, allowing UV light to illuminate the outer disk.
Enhanced Emission: This sudden UV exposure triggered strong PAH emission, revealing chemical activity previously hidden within the disk.
Long-Term Comparison: JWST data from 2022 showed much brighter PAH signatures compared to observations from Spitzer Space Telescope collected in 2002.