ShapleySawyerluokitus

Shapley-Sawyer classification is a method used in the field of astronomy to categorize galaxies based on their shape and structure. It was developed by Harlow Shapley and Helen Sawyer Hogg in the mid-20th century. The classification system is an extension of the Hubble sequence, which is the most commonly used system for classifying galaxies.

The Shapley-Sawyer classification scheme divides galaxies into three main categories: elliptical, spiral, and irregular. Elliptical galaxies are characterized by their smooth, elliptical shape and lack of a distinct structure. They are further divided into subclasses based on their ellipticity, ranging from E0 (nearly spherical) to E7 (highly elongated).

Spiral galaxies, on the other hand, have a distinct structure with a central bulge surrounded by a flat, rotating disk of stars, gas, and dust. They are further divided into subclasses based on the tightness of their spiral arms and the size of their central bulge. The subclasses include Sa (large bulge, tight arms), Sb (medium bulge, medium arms), and Sc (small bulge, loose arms).

Irregular galaxies do not fit into the elliptical or spiral categories and are characterized by their chaotic, irregular shape. They are often the result of interactions or collisions between galaxies.

The Shapley-Sawyer classification system is widely used in astronomical research to study the evolution and structure of galaxies. It provides a useful framework for organizing and comparing galaxies based on their morphological characteristics.