The 18th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG18)

A Stellar Thermometer $^{176}$Lu/$^{176}$Hf of the Main $s$-Process in AGB Stars

Oct 21, 2026, 6:00 PM

3h

Headquarters Building 2F (RIKEN)

Poster Presentation Poster Session

Speakers

Xinxu Wang (Beihang University) Yudong Luo

Description

The $^{176}$Lu ($t_{1/2}\sim$36 Gyr) and $^{176}$Hf are only produced by the main component of the slow neutron capture process (main $s$-process) in AGB stars.
The nucleosynthesis of the isomeric state of $^{176}$Lu$^{m}$ ($t_{1/2}\sim$3 h) dominates the $^{176}$Lu/$^{176}$Hf ratio because it cannot reach the thermal equilibrium with the ground state $^{176}$Lu$^{g}$ at the temperature of the main $s$-process.
We made a comprehensive nucleosynthesis including the $^{176}$Lu isomeric state in the main $s$-process during interpulse phases of two metal-poor stars (LP625$\_$44 and CS31062-012).
The isotopic ratio of $^{176}$Lu/$^{176}$Hf is 0.69 in two stars, which is independent from stellar metalicity, indicating that the ratio can be a stellar thermometer of the main $s$-process in AGB stars.