ARP 220

Definition

ARP 220 is a luminous infrared galaxy located about 250 million light-years away in the constellation Ursa Major, notable for being one of the closest examples of a merging galaxy system. It consists of two colliding galaxies that are undergoing intense star formation as they interact, making it an important subject for understanding galactic cannibalism and the processes that drive galaxy evolution and growth through merger events.

5 Must Know Facts For Your Next Test

1. ARP 220 is classified as a starburst galaxy, where the merging process causes a significant increase in star formation activity, sometimes producing thousands of new stars each year.
2. The two galaxies that make up ARP 220 are thought to be undergoing a merger that has been ongoing for around 100 million years, with the process still in progress.
3. ARP 220 is among the brightest infrared sources in the sky, with its luminosity primarily emitted in the infrared spectrum due to dust obscuring visible light.
4. The intense gravitational forces at play during the merger in ARP 220 lead to the formation of dense clouds of gas and dust, which are the sites of new star formation.
5. Studying ARP 220 provides insights into galactic evolution and helps astronomers understand how such merging events can lead to the growth of larger galaxies over cosmic time.

Review Questions

• How does the interaction between the two galaxies in ARP 220 exemplify the concept of galactic cannibalism?
  • In ARP 220, the two colliding galaxies illustrate galactic cannibalism through their gravitational interaction, where one galaxy can consume parts of another. This process triggers intense star formation as gas and dust are compressed during the collision. As a result, both galaxies influence each other's evolution, ultimately leading to their merger into a larger galaxy.
• Discuss the significance of ARP 220's classification as a starburst galaxy in understanding galactic evolution.
  • ARP 220's status as a starburst galaxy is crucial for understanding how galaxy mergers can trigger rapid star formation. The interaction between the two galaxies generates immense gravitational forces that compress gas and dust, leading to a burst of star production. This phenomenon provides valuable insights into how galaxies evolve over time and how they acquire new mass through mergers.
• Evaluate the implications of studying ARP 220 on our broader understanding of galaxy formation and evolution in the universe.
  • Studying ARP 220 enhances our understanding of galaxy formation and evolution by illustrating how merging events contribute to the growth of galaxies over time. The conditions within ARP 220 reveal key processes involved in star formation triggered by gravitational interactions. These observations allow astronomers to draw parallels between local examples like ARP 220 and similar phenomena observed in distant galaxies, informing theories about the overall dynamics of galaxy development throughout cosmic history.

Related terms

Merging Galaxies: Galaxies that collide and interact gravitationally, often leading to new star formation and significant morphological changes.

Starburst Galaxy: A type of galaxy experiencing an exceptionally high rate of star formation, often due to interactions with other galaxies.

Active Galactic Nucleus (AGN): The central region of a galaxy that is extraordinarily bright and energetic, typically powered by a supermassive black hole accreting material.