Triaxiality

Triaxiality refers to the shape of an object or system that is not symmetric along all three axes. In astronomy, it is commonly used to describe the shape of galaxies. A triaxial galaxy is one where the lengths of the semi-major axes are all different, resulting in an ellipsoidal shape. This is in contrast to an axisymmetric galaxy, which has two equal axes, or a spherical galaxy, which has all three axes equal.

The triaxial shape can be quantified using the triaxiality parameter, T, which ranges from 0 to 1. A value of T=0 indicates a spherical shape, while T=1 indicates a highly elongated shape. Intermediate values represent increasingly triaxial shapes.

Triaxiality is an important factor in understanding the dynamics and evolution of galaxies. It can influence the distribution of stars and gas within a galaxy, as well as the formation of structures like bars and spiral arms. Additionally, triaxiality can affect the gravitational interactions between galaxies and their surroundings.

In the context of other fields, triaxiality can refer to the shape of crystals, the structure of molecules, or the geometry of mechanical components. In each case, it describes a shape that is not symmetric along all three axes, and it can have significant implications for the properties and behavior of the system in question.