Once Hydrogen is used up, a star becomes a ______ _______.
Once Hydrogen is used up, a star becomes a red giant.
Once hydrogen is used up, a star becomes a red giant.
Once hydrogen is used up, a star becomes a red giant.
To understand why this happens, we need to look at the life cycle of a star. Stars are formed from giant clouds of gas and dust in space. The force of gravity pulls these materials together, causing the cloud to collapse. As the matter becomes denser, it heats up and forms a protostar.
The core of a protostar continues to grow hotter and denser until it reaches a critical temperature and pressure, allowing nuclear fusion to occur. At this point, hydrogen atoms within the star's core collide and fuse together to form helium, releasing vast amounts of energy in the process. This energy, in the form of light and heat, is what makes the star shine.
Stars like our Sun spend most of their lives in this main sequence phase, where nuclear fusion of hydrogen into helium occurs in their cores. However, eventually, a star will run out of hydrogen fuel.
When the hydrogen in the core becomes depleted, the star's equilibrium is disrupted. The core contracts under its own gravity, while the outer layers of the star expand. The increase in size causes the star to become a red giant.
During the red giant phase, the outer layers of the star become cooler, while the core continues to contract and heat up. The star's surface becomes much larger and redder, hence the name "red giant." In this phase, the star fuses helium into heavier elements like carbon and oxygen.
Ultimately, the fate of a red giant star depends on its mass. Low to medium-mass stars, like our Sun, will eventually shed their outer layers, forming a planetary nebula and leaving behind a dense core known as a white dwarf. Higher-mass stars, on the other hand, can explode in a supernova, leaving behind remnants such as neutron stars or black holes.