Dwarf elliptical galaxies

Definition

Dwarf elliptical galaxies are small, spheroidal collections of stars that are part of the broader category of elliptical galaxies. They are typically less than one-tenth the size of a standard elliptical galaxy and have a low surface brightness, making them difficult to observe. Despite their size, they are significant for understanding galaxy formation and evolution, particularly in relation to larger elliptical galaxies and their interactions within galaxy clusters.

5 Must Know Facts For Your Next Test

1. Dwarf elliptical galaxies contain mostly older stars and exhibit very little new star formation due to their limited supply of gas and dust.
2. They often reside in clusters or groups, where they can interact with larger galaxies, affecting their structure and evolution.
3. Dwarf ellipticals can vary significantly in size and luminosity, but they generally have a smooth appearance without distinct features like spiral arms.
4. These galaxies are thought to have formed early in the universe's history and may be remnants of larger galaxies that have lost their gas through interactions or mergers.
5. Dwarf elliptical galaxies contribute to the overall mass and dynamics of galaxy clusters, playing a role in the gravitational balance within these larger structures.

Review Questions

• How do dwarf elliptical galaxies differ from larger elliptical galaxies in terms of structure and star formation?
  • Dwarf elliptical galaxies are smaller and less luminous than larger elliptical galaxies, typically having a low surface brightness and lacking the complex structures found in their larger counterparts. They predominantly contain older stars and show minimal star formation due to a scarcity of gas and dust. In contrast, larger elliptical galaxies can host a mix of stellar populations and may have regions of active star formation, particularly if they are interacting with other galaxies.
• Discuss the role of dwarf elliptical galaxies within galaxy clusters and how they might interact with larger galaxies.
  • Within galaxy clusters, dwarf elliptical galaxies play a crucial role as they contribute to the overall mass and gravitational dynamics of the cluster. Their interactions with larger galaxies can lead to various outcomes, including mergers or tidal stripping of their gas and stars. These interactions can strip dwarf ellipticals of their remaining gas, preventing future star formation and altering their structure over time. Such processes highlight the importance of these smaller galaxies in understanding the evolutionary history of clusters.
• Evaluate the significance of dwarf elliptical galaxies in studying galaxy formation and evolution in the universe.
  • Dwarf elliptical galaxies provide valuable insights into the processes of galaxy formation and evolution due to their early emergence in the universe's history. By studying these small galaxies, astronomers can gain a better understanding of how larger galaxies form through mergers and interactions. Their relatively simple structures allow researchers to analyze the effects of environment on galaxy evolution, revealing how factors such as gas loss and stellar population age distribution influence galactic characteristics. This makes dwarf elliptical galaxies essential for piecing together the history and development of galaxies throughout cosmic time.

Related terms

Elliptical galaxies: A type of galaxy characterized by an ellipsoidal shape and a smooth, featureless light profile, often containing older stars and little interstellar gas.

Galaxy clusters: Groups of galaxies held together by gravity, where interactions between different types of galaxies can occur, influencing their evolution.

Star formation: The process by which dense regions within molecular clouds collapse under gravity to form new stars, which is often limited in dwarf elliptical galaxies due to their low gas content.