Definition

Proper noun * Alpha Orionis: The Bayer designation for the brightest star in the constellation Orion. It is a red supergiant star and is commonly known by its traditional name, Betelgeuse.

Usage Notes

• Alpha Orionis is the formal astronomical name. In common usage, including in news and popular science, the star is almost exclusively referred to as Betelgeuse.
• The name follows the Bayer designation system, where the brightest star in a constellation is typically designated "Alpha" (α) followed by the genitive form of the constellation's Latin name. Therefore, literally means "the Alpha star of Orion."

Examples

• In scientific context:
  • The star Alpha Orionis is a variable star whose changes in brightness are closely monitored by astronomers.
  • Studies of Alpha Orionis help us understand the late stages of massive stellar evolution.
• Explaining the naming:
  • While most people know it as Betelgeuse, its official designation in star catalogs is Alpha Orionis.

Advanced Usage

• The name is used in technical astronomical literature, catalogs, and precise scientific discussions to avoid ambiguity, as traditional star names can have multiple spellings or origins.

Variants and Related Words

• Betelgeuse (Proper noun): The universally accepted common name for Alpha Orionis.
• α Orionis (Symbol): The abbreviated symbolic form of the Bayer designation.
• HD 39801: One of its designations in the Henry Draper star catalog.
• Red supergiant (Noun): The stellar classification of Alpha Orionis.

Important Clarification

• The provided reference context describes it as "the second brightest star in Orion." This is a common point of confusion. While Betelgeuse (Alpha Orionis) is visually the brightest star in Orion most of the time, Rigel (Beta Orionis) is intrinsically more luminous. Due to Betelgeuse's high variability, the two stars can occasionally appear very similar in brightness, leading some sources to list Rigel as the brightest. However, by the formal Bayer designation convention, the brightest star is given the "Alpha" label, which is why the star is named Alpha Orionis.

Noun

1. the second brightest star in Orion