What is the Bayer designation of the star Aldebaran?

Aldebaran is designated as Alpha Tauri in the Bayer classification system. The Bayer designation system assigns Greek letters to stars within a constellation, traditionally starting with "Alpha" for the brightest star in that constellation, followed by "Beta," "Gamma," and so on. Aldebaran is the brightest star in the constellation Taurus, which is why it is referred to as Alpha Tau. This designation reflects its prominent status within its constellation as well as its brightness compared to other stars in Taurus.

Knowing that the other options represent different stars can help contextualize this answer. Alpha Centauri refers to the closest star system to the Sun located in the constellation Centaurus, while Alpha Lyr denotes the brightest star, Vega, in the constellation Lyra. Beta Aur is another star in the constellation Auriga, demonstrating that the Bayer designation is unique to each constellation. Hence, Alpha Tau is the precise and correct designation for Aldebaran.