Acrux

Acrux, designated Alpha Crucis (α Cru), is the brightest star in Crux, the Southern Cross, a prominent asterism in the southern sky. It is a multiple star system located about 320 light-years from Earth, based on parallax measurements that place it at roughly 98 parsecs.

The primary component, Acrux A, is a hot blue-white B-type star (approximately classified as B0.5 IV–V). The system includes at least one fainter companion, making Acrux a spectroscopic binary. The combined apparent magnitude of the system is about 0.8, placing it among the brightest stars visible from southern latitudes.

Acrux is part of the five-star Southern Cross asterism, which serves as a well-known navigational feature in many cultures of the southern hemisphere. Observationally, Acrux is most easily observed from southern regions; it forms one of the brighter anchors of the cross and is typically visible during the southern hemisphere’s autumn and winter months.

Distance estimates for Acrux come from astrometric data collected by missions such as Hipparcos and Gaia. Its position within Crux contributes to the prominent silhouette of the cross against the Milky Way, making it a frequent subject of astronomical observation and sky lore in the southern hemisphere.