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
Southern Star Central Gas Pipeline Southern Star Central Gas Pipeline Southern Star Central Gas Pipeline, Inc, headquartered in Owensboro, Kentucky, is a natural gas transmission system spanning over in the Midwest and Mid-continent regions of the United States. Southern Star's employees and its pipeline system and facilities are located throughout Kansas, Oklahoma, Missouri, Wyoming, Colorado, Texas, Nebraska, and Kentucky. It serves major markets such as St. Louis, Wichita, and Kansas City. Southern Star is a locally managed, private company owned by GE Energy Financial Services and Caisse de dépôt et placement du Québec. The company is more commonly referred to as Southern Star. The company's