The Arp Atlas of Peculiar Galaxies is a catalog of unusual and interesting galaxies compiled by astronomer Halton Arp in 1966. It consists of 338 entries and is an important resource for studying galaxy morphology and interactions. Here’s a detailed overview:
Background
- Compiled by: Halton Arp, an American astronomer.
- Publication: The catalog was first published in 1966.
- Purpose: To document and categorize galaxies with unusual or peculiar shapes, often as a result of interactions or collisions.
Categories of Peculiar Galaxies
The galaxies in the Arp Atlas are grouped into various categories based on their peculiarities:
- Interacting Galaxies:
- Description: Galaxies that are in the process of interacting or colliding with each other.
- Arp 87: A pair of interacting galaxies with a distorted appearance.
- Arp 220: A famous example of a galactic collision, resulting in intense star formation.
- Description: Galaxies that are in the process of interacting or colliding with each other.
- Disturbed or Irregular Galaxies:
- Description: Galaxies that have irregular shapes or structures due to internal or external forces.
- Arp 299: A pair of galaxies showing significant disturbances and ongoing star formation.
- Description: Galaxies that have irregular shapes or structures due to internal or external forces.
- Galaxies with Tidal Tails or Bridges:
- Description: Galaxies with long, thin structures extending from them, often caused by gravitational interactions.
- Arp 148: Features prominent tidal tails.
- Description: Galaxies with long, thin structures extending from them, often caused by gravitational interactions.
- Galaxies with Eccentric Morphologies:
- Description: Galaxies that have unusual shapes that do not fit typical categories, such as spiral or elliptical.
- Arp 284: A galaxy with an unusual morphology that does not fit into standard classifications.
- Description: Galaxies that have unusual shapes that do not fit typical categories, such as spiral or elliptical.
- Galaxies with Ring Structures:
- Description: Galaxies that have ring-like structures around their centers, often due to interactions or central activity.
- Arp 151: A galaxy with a prominent ring structure.
- Description: Galaxies that have ring-like structures around their centers, often due to interactions or central activity.
- Elliptical Galaxies with Peculiar Features:
- Description: Elliptical galaxies that have unusual features, such as dust lanes or non-standard shapes.
- Arp 229: An elliptical galaxy with peculiar features.
- Description: Elliptical galaxies that have unusual features, such as dust lanes or non-standard shapes.
Notable Galaxies in the Arp Atlas
- Arp 273: A pair of interacting spiral galaxies.
- Arp 147: A galaxy with a distinctive double nucleus.
- Arp 102: A peculiar galaxy with a bright central region and extended outer structure.
Significance and Usage
- Research: The Arp Atlas has been used extensively in studies of galaxy formation and evolution, interactions, and peculiar phenomena.
- Observational Studies: Many of the galaxies in the atlas have been the subject of detailed observational studies using various wavelengths, providing insights into their structure and behavior.
Visual Representation
The Arp Atlas includes images of the galaxies, often showing their peculiarities and interactions. These images have been used to illustrate various phenomena in galactic dynamics and morphology.
