Eddington Limit

Definition

The Eddington Limit is the maximum luminosity a star can achieve when there is a balance between the outward radiation pressure from its light and the inward gravitational pull. This limit is crucial for understanding stellar stability, as exceeding it can lead to the loss of mass and eventually affect the formation and evolution of stars.

5 Must Know Facts For Your Next Test

1. The Eddington Limit is approximately 1.5 × 10^{38} watts for a star with one solar mass.
2. Stars exceeding the Eddington Limit can lose mass at an accelerated rate due to intense radiation pressure overpowering gravity.
3. This limit is particularly relevant for massive stars, where their high luminosity can lead to significant mass loss through strong stellar winds.
4. When a star approaches the Eddington Limit, it may enter a phase of instability, leading to changes in its structure and evolutionary path.
5. Understanding the Eddington Limit helps astronomers predict the life cycle of stars and their potential to form black holes or neutron stars.

Review Questions

• How does the Eddington Limit relate to the balance between radiation pressure and gravitational force in stars?
  • The Eddington Limit represents the point where the outward radiation pressure from a star's luminosity balances the inward gravitational force acting on it. When a star is below this limit, gravity dominates, allowing it to maintain its structure. However, as a star's luminosity increases and approaches this limit, radiation pressure becomes more significant, threatening to overpower gravity and potentially destabilizing the star.
• Discuss the implications of exceeding the Eddington Limit for a massive star's evolution.
  • Exceeding the Eddington Limit has profound implications for a massive star's evolution. When a star surpasses this threshold, it may experience accelerated mass loss due to increased radiation pressure that can drive away material. This loss of mass can alter its life cycle, leading to faster evolution toward supernova events or even the formation of black holes, impacting surrounding stellar environments.
• Evaluate how understanding the Eddington Limit enhances our knowledge of stellar formation and black hole creation.
  • Understanding the Eddington Limit enriches our grasp of stellar formation by illustrating how luminosity influences mass retention in stars. It reveals that massive stars must navigate this limit carefully to avoid rapid mass loss that could prevent them from forming black holes. As researchers study various stellar masses and their luminosities in relation to the Eddington Limit, they can better predict which stars are likely to end their lives as black holes, thus refining models of stellar evolution and cosmic structure.

Related terms

Radiation Pressure: The pressure exerted by electromagnetic radiation on surfaces, which plays a critical role in counteracting gravitational forces in stars.

Luminosity: The total amount of energy radiated by a star per unit time, which is essential for determining its position on the Hertzsprung-Russell diagram.

Mass Loss: The process by which a star loses its mass due to stellar winds or other mechanisms, often influenced by its luminosity and proximity to the Eddington Limit.