Context:

Indian astronomers have detected singly-ionized germanium (Ge II) in a rare type of star known as an Extreme Helium (EHe) star, specifically in the star A980.

What are Extreme Helium (EHe) Stars?

• EHe stars are extremely rare, hydrogen-deficient stars composed primarily of helium with traces of heavier elements.
• Fewer than a few dozen such stars have been identified so far.
• The leading theory behind their formation is the merger of two white dwarf stars — one rich in helium and the other rich in carbon and oxygen.
• These stars are characterized by low surface gravity and relatively cool temperatures, and they exhibit unusual chemical compositions that set them apart from typical stars.

Why is the Detection of Germanium Significant?

• Germanium is a heavy element typically produced via the s-process (slow neutron capture) during the Asymptotic Giant Branch (AGB) phase of stellar evolution.
• The discovery of germanium in EHe star A980 suggests the material underwent nucleosynthesis before the merger of the white dwarfs.
• This finding provides insights into the star's pre-merger history and enhances our understanding of the chemical evolution of such rare stellar systems.

Source: PIB