Red-giant branch through several distinct stages which are reflected in the outward appearance. The evolutionary stages vary depending primarily on the mass of the star, but also on its metallicity. After a main-sequence star has exhausted its core hydrogen, it begins to fuse hydrogen in a thick shell around a core consisting largely of helium. The mass of the helium core is below the Schönberg–Chandrasekhar limit and is in thermal equilibrium, and the star is a subgiant. Any additional energy production from the shell fusion is consumed in inflating the envelope and the star cools but does not increase in luminosity. Shell
Red and white giant flying squirrel found in mountain areas, they nest in hollow trees. They move between the trees of their ecosystem by gliding by use of a patagium, typically over distances of 10–20 meters although glides of up to 400 meters longer have been observed when they happen to be traveling downhill. This species has a wide distribution and a presumed large population, it occurs in many protected areas, and the International Union for Conservation of Nature has rated it as being of "least concern". Red and white giant flying squirrel The red and white giant flying squirrel ("Petaurista alborufus") is a species of