Faber-Jackson Relation – Definition & Detailed Explanation – Astrophysics Glossary

I. What is the Faber-Jackson Relation?

The Faber-Jackson Relation is a fundamental relationship in astrophysics that describes the correlation between the luminosity and velocity dispersion of elliptical galaxies. In simple terms, it states that the brighter an elliptical galaxy is, the faster its stars are moving within it. This relationship was first discovered in the 1970s by astronomers Sandra Faber and Robert Jackson, hence the name Faber-Jackson Relation.

II. How was the Faber-Jackson Relation discovered?

The discovery of the Faber-Jackson Relation was a result of groundbreaking research conducted by Faber and Jackson in the 1970s. They used data from the Palomar Observatory Sky Survey, which provided detailed images and spectra of thousands of galaxies. By measuring the velocity dispersion of stars in elliptical galaxies and comparing it to their luminosity, Faber and Jackson were able to establish a clear correlation between the two properties.

III. What does the Faber-Jackson Relation tell us about galaxies?

The Faber-Jackson Relation provides valuable insights into the formation and evolution of galaxies. It suggests that the luminosity of an elliptical galaxy is closely related to the total mass of the galaxy, as the velocity dispersion of stars is directly related to the gravitational potential of the galaxy. This implies that brighter galaxies are more massive and have stronger gravitational forces holding their stars together.

IV. How is the Faber-Jackson Relation used in astrophysics?

The Faber-Jackson Relation is a powerful tool in astrophysics that allows astronomers to estimate the mass of galaxies based on their luminosity. By measuring the velocity dispersion of stars in a galaxy and using the Faber-Jackson Relation, researchers can infer the total mass of the galaxy, even if it is not directly observable. This has important implications for understanding the dynamics and evolution of galaxies in the universe.

V. What are the limitations of the Faber-Jackson Relation?

While the Faber-Jackson Relation is a valuable tool in astrophysics, it does have some limitations. One major limitation is that it only applies to elliptical galaxies, as the relationship between luminosity and velocity dispersion is not as clear for other types of galaxies, such as spiral galaxies. Additionally, the Faber-Jackson Relation assumes that all galaxies have the same stellar populations, which may not always be the case.

VI. How has the Faber-Jackson Relation impacted our understanding of the universe?

The discovery of the Faber-Jackson Relation has had a profound impact on our understanding of the universe. By providing a direct link between the luminosity and mass of galaxies, this relationship has helped astronomers study the distribution of dark matter in galaxies, the formation of galaxy clusters, and the evolution of galaxies over time. The Faber-Jackson Relation continues to be a valuable tool in astrophysics, shedding light on the mysteries of the cosmos.