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When do stars become red giants?
Stars become red giants when they have exhausted their hydrogen fuel in the core and start burning helium, causing the outer layers to expand and cool. This expansion turns the star into a large, cool, and luminous red giant.
When a star has exhausted its supply of hydrogen?
When hydrogen in the core of the star is depleted, a balance no longer exists between pressure and gravity. Core contracts, temperatures incrase. This causes outer layers to expand and cool. This star is called a GIANT.
What are the large cool stars that are not in the main sequence?
Red giants. They are medium and large stars that have used up all of their hydrogen and gave begun burning the helium. They begin to expand while they are in their "dying" phase. They will ultimately become a white dwarf if they were a medium sized star during their main sequence, or they will become a black hole or a neutron star if they were a large star during their main sequence.
The large cool stars found at the upper right of the H-R diagram are stars?
The large, cool stars found at the upper right of the H-R diagram are red giants. These stars are in a later stage of their evolution, where they have exhausted their core hydrogen fuel and expanded in size. They are cooler in temperature but have a large luminosity due to their increased surface area.
What does a star become when it expands and outer layers cool?
When a star expands and its outer layers cool, it becomes a red giant. This occurs in the later stages of a star's life cycle, particularly for stars with masses similar to the Sun. The expansion is caused by the star running out of hydrogen fuel in its core and beginning to fuse helium into heavier elements.
What does a star become when it casts off hydrogen and helium gases in its outer layers?
When a star exhausts its hydrogen and helium in the outer layers, it can become a red giant and eventually shed those outer layers, leading to the formation of a planetary nebula. The core that remains can become a white dwarf, which is a dense, hot remnant that will gradually cool over time. This process marks the later stages of stellar evolution for medium-sized stars.
Why are the hydrogen Balmer lines strong in the spectra of medium temperature stars and weak in the spectra of hot and cool stars?
Balmer lines are produced by colliding hydrogen atoms with electrons excited to 2nd energy level. Cool stars don't have enough collision to excite the electrons, hot stars have too much collision and excite the electrons beyond 2nd energy level.
What is true of the layers of a star?
the inner layers are very cool, the outer layers are somewhat cool
What element is the main fuel for red giant stars?
The main fuel for red giant stars is helium. In the core of red giant stars, hydrogen fusion has ceased, and as the star evolves, it starts fusing helium into heavier elements like carbon and oxygen. This process produces the energy that sustains the star's outer layers and causes it to expand and cool, creating a red giant.
What is a large cool star form when a star runs out of hydrogen?
When a star runs out of hydrogen in its core, it starts fusing helium into heavier elements like carbon and oxygen. This process causes the outer layers of the star to expand and cool, becoming a red giant.
A star that has exhausted it's supply of hydrogen?
It will begin to swell and may start it's red giant phase. The stars preferred fuel is hydrogen, but once this had been used it will start to fuse helium. The temperature of the core will rise and the output energy and gravity battle will shift, causing the star to become larger.
Does nuclear fusion occurs as stars cool down?
The star will continue to fuse hydrogen until it runs out of resources and dies out, after which it will collapse and die.
