The life cycle of a Sun-like star
A Sun-like star follows a predictable life cycle driven by nuclear fusion. It spends approximately 10 billion years in the main sequence phase, fusing hydrogen into helium in its core. When hydrogen fuel runs out, the core collapses and heats up, causing hydrogen to fuse in a surrounding shell. This pushes the outer layers outward, transforming the star into a red giant. Eventually, the exhausted core becomes a dense white dwarf, while outer layers disperse as a planetary nebula. Understanding this cycle matters because it reveals the Sun's future, explains stellar evolution throughout the universe, and shows how stars distribute elements to their surroundings over billions of years.
Sources
- en.wikipedia.org: “A G-type main-sequence star with the mass of the Sun will fuse hydrogen for approximately 10 billion years, until the hydrogen is exhausted at the core of the star.”
- en.wikipedia.org: “Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red-giant phase.”
- en.wikipedia.org: “Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula.”