IIA Scientists Unveil Unprecedented Germanium-Rich Star, Challenging Conventional Stellar Chemistry

Bengaluru, June 19- In a groundbreaking astronomical discovery, scientists from the Indian Institute of Astrophysics (IIA), Bengaluru, have identified a stellar anomaly that could reshape our understanding of how heavy elements are forged in the universe.

The focus of the study is a distant star named A980, located approximately 25,800 light years away in the Ophiuchus Constellation. Initially believed to be a hydrogen-deficient carbon (HdC) star, this enigmatic celestial body has now been reclassified as an Extreme Helium (EHe) star — a rare and unusual class of stars primarily composed of helium.

Using high-resolution observations from the Hanle Echelle Spectrograph installed on the Himalayan Chandra Telescope in Ladakh, researchers were struck by an unexpected discovery: clear spectral evidence of singly-ionized germanium (Ge II)—a metallic element that has never before been detected in this type of star.

“This is the first confirmed observation of germanium in an EHe star, and it’s found in astonishing abundance—eight times higher than in our Sun,” remarked Ajay Saini, lead researcher and PhD scholar at IIA.

Germanium, a heavy element forged in stellar environments, is typically associated with the slow neutron capture process (s-process), a nuclear mechanism believed to occur during the Asymptotic Giant Branch (AGB) phase of a star’s life. The presence of such elements in A980 strongly hints at a dramatic stellar merger in its past—likely involving a carbon-oxygen white dwarf and a less massive helium white dwarf.

The findings also align A980 with another extremely rare cool EHe star, LS IV -14° 109, suggesting a potentially shared origin or evolutionary pathway. Spectral comparisons between A980 and other known EHes revealed multiple enhanced s-process elements, making A980 stand out even among its rare peers.

While the dominant theory supports a white dwarf merger, researchers are not ruling out other exotic possibilities. One such scenario involves Thorne–Żytkow Objects (TŻOs)—hypothetical hybrid stars featuring a neutron star engulfed by a red supergiant. These unique objects are also believed to produce germanium, albeit via a different method known as the rapid proton capture process (rp-process). Although A980 doesn’t fully fit the TŻO profile, the chemical similarities are compelling enough to merit further investigation.

“This finding opens a fresh window into the complex chemistry of stars,” said Dr. Gajendra Pandey, senior scientist at IIA and co-author of the study. “It challenges established models of stellar evolution and highlights the power of high-resolution spectroscopy in decoding the stories embedded in starlight.”

The discovery has been documented in The Astrophysical Journal, marking a significant achievement for India’s astronomical community and offering new insights into how the universe manufactures its heavier elements.

As scientists continue to decipher the cosmic fingerprints of A980, this lone star may hold answers to some of the deepest questions about the origins of matter and the life cycles of stars.