Aero-Terms!

Aero-Terms are designed to be a daily reminder of the terms, names, acronyms and explanations of the unique language that populates the aviation world. Aerospace, sport aviation, fixed wing, helo, you name it... it's all fair game.

Aero-Terms should serve as a quick but intriguing reminder of the terms you may use every day, or an introduction to an aspects of the Aero-World you may not yet be familiar with. ANN also encourages readers to go beyond the FMI link, and further research any intriguing terms.

Suggestions for future Aero-Terms are ALWAYS welcome, as are additions or discussion of the explanations given for each Aero-Term.

D Galaxy

A luminous giant elliptical galaxy typically found near the center of a cluster of galaxies. D galaxies are similar in appearance to ordinary ellipticals, but their brightness declines more slowly with distance from the center, making them look as if they have diffuse halos (the "D" stands for "diffuse".) A CD galaxy is even bigger and brighter and is found centrally located in a rich cluster of galaxies. CD galaxies are believed to have grown so large through galaxy mergers. Indeed, several CD galaxies are observed to have multiple galactic nuclei, as if they are still in the process of cannibalizing smaller systems. 

FMI: http://www.encyclopedia.com/doc/1O80-Dgalaxy.html