Mu1 Gruis

Mu1 Gruis (μ¹ Gruis) is a red giant star located in the constellation Grus (The Crane). It is approximately 430 light-years from Earth. Mu1 Gruis is classified as an S-type star, indicating that its spectrum shows absorption lines of heavy elements, particularly strontium and zirconium, which are created through the s-process of nucleosynthesis in its core. These elements are then dredged up to the surface by convection.

Mu1 Gruis is a pulsating variable star, specifically a Mira variable. This means its brightness varies significantly over a long period. Its period of pulsation is around 480 days. As a Mira variable, Mu1 Gruis undergoes significant changes in both temperature and radius throughout its pulsation cycle, leading to the variations in luminosity.

The star's outer layers are extended and tenuous, making it susceptible to mass loss through stellar winds. This mass loss contributes to the formation of a circumstellar envelope around the star, which is rich in molecules and dust. Studies of this envelope provide valuable insights into the processes of stellar evolution and the return of processed material to the interstellar medium. The ejected material ultimately enriches the interstellar medium with heavier elements, contributing to the formation of new stars and planetary systems.

Mu1 Gruis is nearing the end of its life cycle. Having exhausted the hydrogen in its core, it has expanded into a red giant and is now fusing helium into carbon and oxygen. Eventually, it will expel its outer layers to form a planetary nebula, leaving behind a white dwarf remnant.