Gamma Velorum

Gamma Velorum (γ Vel, γ Velorum) is a star system in the constellation Vela. At magnitude +1.7, it is one of the brightest stars in the night sky. It has the traditional names Suhail and Suhail al Muhlif, which confusingly also apply to Lambda Velorum. It also has a more modern popular name Regor, which was invented as a practical joke by the Apollo 1 astronaut Gus Grissom for his fellow astronaut Roger Chaffee. Due to the exotic nature of its spectrum (bright emission lines in lieu of dark absorption lines) it is also dubbed the "Spectral Gem of Southern Skies".

The Gamma Velorum system is composed of at least six stars. The brightest member, γ² Velorum or γ Velorum A, is actually a spectroscopic binary composed of a blue supergiant of spectral class O7.5 (~30 M_☉), and a massive Wolf-Rayet star (~9 M_☉, originally ~35 M_☉). The binary has an orbital period of 78.5 days and separation of 1 AU. The Wolf-Rayet star is likely to end its life in a Type Ic supernova explosion; it is one of the nearest supernova candidates to the Sun. Its nearest companion, the bright (apparent magnitude +4.2) γ¹ Velorum or γ Velorum B, is a blue-white B-type subgiant. It is separated from the Wolf-Rayet binary by 41.2", and the separation can easily be resolved with binoculars.

Gamma Velorum has several fainter companions. The magnitude +8.5 γ Velorum C, a white A-type star, is 62.3 arcseconds from the A component. At 93.5 arcseconds is the system's second binary star, γ Velorum D and E. The D component is another A-type star which has a magnitude of +9.4. Its companion is a 13th magnitude star, separated by 1.8 arcseconds.

The Chinese name for the star is 天社一 (Mandarin: tiān shè yī), which means "The First Star of the Celestial Altar."