Bengaluru Researchers Unveil Groundbreaking Stellar Chemistry Discovery

BENGALURU, India – On July 15, 2025, researchers from the Indian Institute of Astrophysics (IIA) in Bengaluru made a significant breakthrough in stellar chemistry, unveiling the unexpected properties of a peculiar star named A980 located approximately 25,800 light years away in the Ophiuchus constellation. This discovery challenges existing theories in astrophysics and enhances our understanding of stellar evolution.

The research, led by Gajendra Pandey, Senior Professor at IIA, and his PhD student Ajay Saini, originated from Saini's thesis project, which aimed to study 27 newly identified hydrogen-deficient carbon stars using high-resolution spectroscopy. "Hydrogen-deficient carbon stars are a unique category of stars that have a deficiency of hydrogen, the most abundant element in the universe," Pandey explained. Prior to 2022, only five such stars were known, but the identification of 27 additional stars, including A980, prompted a closer examination of their chemical compositions.

Utilizing the Hanle Echelle Spectrograph on the Himalayan Chandra Telescope, Saini and Pandey conducted detailed spectral analysis and were astonished to find that the spectrum of A980 deviated significantly from their expectations. Instead of the anticipated composition, they identified a remarkable abundance of germanium in this star, a metallic element not previously observed in Extreme Helium (EHe) stars.

According to Pandey, the presence of germanium lines (Ge II) in A980’s optical spectrum represents the first-ever detection of this element in the observed spectrum of an EHe star. "Our findings revealed that germanium is eight times more abundant in A980 than in the Sun, indicating the possibility of germanium synthesis within these stars," Saini noted. This discovery is pivotal, as it suggests alternative formation scenarios for EHe stars beyond the traditionally accepted theory of their origin from the merger of two white dwarfs—with one being carbon-oxygen rich and the other helium-rich.

The discovery of A980’s unusual chemistry may also connect to a phase in stellar evolution known as the Asymptotic Giant Branch (AGB), during which stars expand and produce heavy elements such as barium, strontium, and germanium. These stars eventually lose their outer layers, leaving behind white dwarf cores.

Furthermore, the researchers speculated about the potential role of Thorne-Żytkow Objects (TŻOs)—theoretical hybrid stars with neutron star cores—which are believed to produce significant amounts of germanium through a different process known as the rapid proton capture (rp-process). Although A980 does not fully align with the characteristics of a TŻO, the similarities warrant further investigation.

This research, now published in The Astrophysical Journal, not only expands the boundaries of known stellar chemistry but also emphasizes the power of high-resolution spectroscopy in revealing the complex narratives encoded in starlight. Pandey stated, "A980 presents us with a new puzzle, one that could deepen our understanding of the evolution of rare stars and the dynamics involved in white dwarf collisions."

In summary, this groundbreaking discovery made by researchers in Bengaluru underscores the ongoing need for detailed astronomical studies and the potential for new insights into the universe’s chemical evolution. As scientists continue to unravel the mysteries of stellar chemistry, the implications of findings like those pertaining to A980 may reshape our understanding of cosmic processes and the lifecycle of stars.