Osmium
Osmium maintains substantial astronomical intrigue due to its exceptional rarity, unique properties, and potential implications for understanding celestial phenomena. Synthesized during nucleosynthesis processes within stars, especially in cataclysmic events like supernovae and neutron star mergers, osmium stands as one of the scarcest elements both on Earth and in the wider cosmos. Its distinct spectral lines, notably observed across specific wavelengths in the ultraviolet and visible spectra, serve as vital markers aiding astronomers in identifying osmium within stars and facilitating analysis of their compositions and environmental conditions. However, detecting osmium in interstellar space or within stars remains profoundly challenging owing to its extreme rarity, making its contribution to observed cosmic chemical compositions minimal or extremely challenging to discern using existing observational techniques.