Astrophysics & Particle Physics-APPC 2026

Red giants are stars in the final stages of stellar evolution whose core hydrogen fuel has been exhausted and expanded enormously in size. They are defined by their enormous radii, high luminosities, and cooler surface temperatures, which result in a reddish coloration. Red giants are key to the study of stellar lifecycles and galactic chemical enrichment.Red giants form from low- to intermediate-mass stars (0.5–8 solar masses) once they have exhausted the main sequence. The hydrogen in the core gets exhausted, resulting in contraction and heating of the core and expansion of the outer layers.

Hydrogen continues to burn in a shell around the inert helium core, and later helium is ignited in the core via the helium flash in low-mass stars or steady helium burning in more massive stars.Red giants are observed using optical, infrared, and spectroscopy, which yield temperature, chemical composition, and internal structure. Their location on the Hertzsprung-Russell diagram assists astronomers in simulating stellar evolution and estimating stellar ages within clusters and galaxies.To conclude, red giants are evolved, luminous stars that offer information regarding stellar evolution, nucleosynthesis, and enrichment of the interstellar medium. Researching these stars increases our knowledge of the lifecycle of stars, their demise, and the recycling of material back into the universe.