Aα, or Alpha, is the first letter of the Greek alphabet. It is commonly used in various fields, including mathematics, science, and finance, to represent different concepts. In mathematics, for example, Aα can denote angles or coefficients in equations. In the context of physics, Aα often refers to alpha particles, which are a type of radiation emitted by certain radioactive materials. These particles consist of two protons and two neutrons, making them relatively heavy compared to other forms of radiation. Alpha particles play a significant role in nuclear reactions and are important in the study of nuclear physics.