Alpha Cru
HIP 60718; Alpha2 Cru
Sep: 4.4", Companion: mag 1.6
Physical Properties
Position & Identifiers
Visibility
Set a location in User Settings to see visibility data.
Multiple Star System
Eyepiece View
Sep: 4.4″ · PA: 111° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″
Size Comparison
Stellar Lifecycle
Spectral Classification
Hertzsprung-Russell Diagram
Blackbody Spectrum
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
Stellar Notes
Survey Image
Loading survey image…
About Alpha Cru
Description
Alpha Crucis B is the fainter component of the Acrux double star system at magnitude 1.73, a blue main-sequence star of spectral type B1V. Together with the brighter A component, it forms one of the finest visual double stars in the southern sky. The B component has a luminosity of about 16,000 times solar.
Observing Tips
Resolved in a small telescope at moderate magnification as the fainter companion to Acrux A, separated by about 4 arcseconds. The pair appears as two brilliant blue-white points, nearly equal in brightness. This is one of the most rewarding double stars accessible from the southern hemisphere. Best observed March through June.
History
The double nature of Acrux was first noted by Jesuit missionary Jean Richaud while observing a comet from Pondicherry, India in 1685. It was one of the first double stars discovered in the southern sky and remains one of the showpiece objects for southern hemisphere observers.
Fun Facts
The two components of Acrux are among the nearest pair of B-type giants to Earth that can be resolved visually. The system may actually contain additional components, making it a quadruple or even quintuple star system.