Dubnium
Dubnium is a synthetic and highly radioactive element created artificially through human-made nuclear reactions and is essentially non-existent in natural astronomical contexts. Its artificial production renders dubnium exceptionally rare beyond Earth, leading to minimal astronomical significance. The isotopes of dubnium exhibit extremely short half-lives, typically lasting from milliseconds to minutes, further highlighting its absence in celestial bodies or cosmic environments. Dubnium's synthetic nature confines its presence primarily to controlled laboratory settings, such as in nuclear reactors or as a byproduct of nuclear processes.