What is a distinguishing feature of elliptical galaxies?

Elliptical galaxies are primarily characterized by their lack of spiral arms. This distinct feature sets them apart from spiral galaxies, which are defined by their structured arms winding around a central nucleus. Instead, elliptical galaxies have a smooth, featureless light profile and generally possess a more three-dimensional, spheroidal shape without the organized structure seen in spiral arms.

The absence of prominent structures like spiral arms indicates that the star populations in elliptical galaxies tend to be older and more uniformly distributed. In many cases, these galaxies are composed mostly of older stars, contributing to a more uniform color and brightness. This contrasts with the younger, hot stars often found within the spiral arms of spiral galaxies. The structure and characteristics of elliptical galaxies reflect their formation and evolutionary processes, which tend to involve mergers and interactions that smooth out the original features of galactic structure.