Chapter 16: Problem 35
Suppose a star is able to heat its core temperature high enough to begin fusing oxygen. Predict how the star will continue to evolve, including how you think the star will evolve on the H-R diagram.
Short Answer
Expert verified
The star, in its final life stages, will undergo a supernova and possibly form a neutron star or black hole, moving off the H-R diagram after reaching high luminosity and low temperature.
Step by step solution
01
- Identify the star's current status
Determine the star's current phase in its life cycle. Given that the star can begin fusing oxygen, it is likely a massive star, previously in the supergiant phase after having exhausted hydrogen and helium supplies.
02
- Understand oxygen fusion
Recognize that oxygen fusion occurs at extremely high temperatures (around a billion degrees Kelvin) and typically happens in massive stars close to the end of their lifecycle.
03
- Predict the next stages in the star's evolution
When a star begins fusing oxygen, it generally signifies the star is in its final stage of nuclear burning. This phase is short-lived and will be followed by successive stages of fusing heavier elements until iron is produced.
04
- Consider the star's fate
After reaching iron fusion, the core becomes inert and can no longer produce energy through fusion. This will lead to core collapse, resulting in a Type II supernova.
05
- Evaluate the star's position on the H-R diagram
On the Hertzsprung-Russell (H-R) diagram, the star will have moved off the main sequence and traversed through the giant branches. During oxygen fusion, it resides in the upper-right region, indicating a high luminosity and lower temperature. After the supernova, the remnant could lead to the formation of a neutron star or black hole, marking the end of the star's life on the H-R diagram.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Oxygen Fusion in Stars
Oxygen fusion in stars is a fascinating process that takes place only in the most massive stars. This phase occurs at incredibly high temperatures, reaching around a billion degrees Kelvin. During this stage, oxygen nuclei collide and fuse to form heavier elements such as silicon and sulfur.
This fusion process releases a tremendous amount of energy but represents a very brief stage in a star's life. As the star exhausts its oxygen supply, it quickly moves on to fuse heavier elements until it reaches iron. The fusion of iron, however, consumes energy rather than releasing it, leading to the next critical phase in the star's evolution.
This fusion process releases a tremendous amount of energy but represents a very brief stage in a star's life. As the star exhausts its oxygen supply, it quickly moves on to fuse heavier elements until it reaches iron. The fusion of iron, however, consumes energy rather than releasing it, leading to the next critical phase in the star's evolution.
Hertzsprung-Russell Diagram
The Hertzsprung-Russell (H-R) diagram is an essential tool in understanding the life cycle of stars. It plots stars according to their luminosity and temperature, effectively showing their evolutionary stages.
A star that begins fusing oxygen will have moved off the main sequence and into the top right region of the diagram. This area is associated with high luminosity and cooler surface temperatures. Stars in this position are known as supergiants.
As the star continues to evolve, it will progress through various stages until it ends its life in a supernova, thus exiting the observable parts of the H-R diagram.
A star that begins fusing oxygen will have moved off the main sequence and into the top right region of the diagram. This area is associated with high luminosity and cooler surface temperatures. Stars in this position are known as supergiants.
As the star continues to evolve, it will progress through various stages until it ends its life in a supernova, thus exiting the observable parts of the H-R diagram.
Supernova
A supernova marks one of the most dramatic and catastrophic events in a star's life. When a massive star exhausts its nuclear fuel, it undergoes a rapid core collapse, resulting in a violent explosion.
This explosion can outshine entire galaxies for a brief period and leads to the dispersal of heavy elements into space. The remnants of this supernova can form either a neutron star or a black hole, depending on the mass of the core. The elements scattered by a supernova are crucial for the formation of new stars and planets, making them key players in cosmic recycling.
This explosion can outshine entire galaxies for a brief period and leads to the dispersal of heavy elements into space. The remnants of this supernova can form either a neutron star or a black hole, depending on the mass of the core. The elements scattered by a supernova are crucial for the formation of new stars and planets, making them key players in cosmic recycling.
Core Collapse
Core collapse is the process that triggers a Type II supernova. When a massive star exhausts its fuel, its core, mainly composed of iron, becomes unable to produce energy through fusion. This leads to a catastrophic gravitational collapse.
The core rapidly contracts, reaching densities so high that protons and electrons combine to form neutrons. This sudden collapse releases a shockwave that propagates outward, causing the outer layers of the star to explode. This sequence of events explains how supernovae are formed and how they contribute to the cosmic landscape.
The core rapidly contracts, reaching densities so high that protons and electrons combine to form neutrons. This sudden collapse releases a shockwave that propagates outward, causing the outer layers of the star to explode. This sequence of events explains how supernovae are formed and how they contribute to the cosmic landscape.
Neutron Star
When a star undergoes a supernova, if the remaining core is between about 1.4 and 3 times the mass of our Sun, it will form a neutron star. Neutron stars are incredibly dense, with a teaspoon of their material weighing billions of tons.
These stars are composed almost entirely of neutrons and have a diameter of only about 20 kilometers. Despite their small size, neutron stars have strong magnetic fields and can rotate rapidly, emitting beams of radiation detectable as pulsars. Neutron stars are one of the ultimate end states of stellar evolution.
These stars are composed almost entirely of neutrons and have a diameter of only about 20 kilometers. Despite their small size, neutron stars have strong magnetic fields and can rotate rapidly, emitting beams of radiation detectable as pulsars. Neutron stars are one of the ultimate end states of stellar evolution.
Black Hole
If the remaining core of a collapsed star exceeds about three times the mass of the Sun, it will form a black hole. Black holes are regions of spacetime where gravity is so strong that nothing, not even light, can escape their pull.
They form the most extreme end state of a star's evolution. The boundary around a black hole, known as the event horizon, marks the point beyond which nothing can return. Black holes continue to captivate scientists and the public alike, offering insights into the most extreme conditions in the universe. They play a crucial role in shaping galaxies and influencing the cosmos at a grand scale.
They form the most extreme end state of a star's evolution. The boundary around a black hole, known as the event horizon, marks the point beyond which nothing can return. Black holes continue to captivate scientists and the public alike, offering insights into the most extreme conditions in the universe. They play a crucial role in shaping galaxies and influencing the cosmos at a grand scale.