Red-giant branch hydrogen fusion continues in stars of roughly solar mass until the helium core increases in mass sufficiently that it becomes degenerate. The core then shrinks, heats up, and develops a strong temperature gradient. The hydrogen shell, fusing via the temperature-sensitive CNO cycle, greatly increases its rate of energy production and the stars is considered to be at the foot of the red-giant branch. For a star the same mass as the sun, this takes approximately 2 billion years from the time that hydrogen was exhausted in the core. Subgiants more than about reach the Schönberg–Chandrasekhar limit relatively quickly before the
Red and white giant flying squirrel Red and white giant flying squirrel The red and white giant flying squirrel ("Petaurista alborufus") is a species of rodent in the family Sciuridae. It is the largest species of giant squirrel and has blue eyes. It is also known as the Chinese giant flying squirrel. At over a meter long including its tail, the red and white giant flying squirrel is the largest of its kind. Endemic to central and southern China and Taiwan, they inhabit dense hillside forests in mountainous terrain. They spend their days sleeping, emerging after sundown to forage in the trees. Their diet consists primarily