| 释义 |
technetium stars technetium stars (tek-nee -shee-ŭm) A class of asymptotic giants (usually S stars or carbon stars) that show absorption lines of technetium in their spectra. Because technetium (99Tc) is an unstable radioactive element decaying with a half-life of 2.1 × 105 years, it must have been produced in the burning shell of the star in which it is observed. See also radioactive decay. |