Gamma Velorum

Gamma Velorum (Regor)

Gamma Velorum is the bright star to the left of center. It is unconnected with the Gum Nebula, which lies in the background. Credit: Southernskyphoto.

Gamma Velorum is the brightest star in the constellation Vela; in fact, it is a spectacular and complex multiple star system. The brightest component, known as Gamma2 Velorum or Gamma Velorum A is itself a spectroscopic binary consisting of the closest known Wolf-Rayet star to Earth and a massive blue giant or blue supergiant (spectral type O7.5Ie) orbiting around each other with a period of 78.5 days at a mean separation of 1 AU (the distance of Earth from the Sun). The hot evolved O star is about 25 times as massive than the Sun and some 200,000 times more luminous with a surface temperature of 35,000 K. Its Wolf-Rayet partner, which is 50,000 times as luminous as the Sun and has a surface temperature of 60,000 K, probably started out with a mass of about 40 times that of the Sun but has shed much of that original material to be left with only about 10 solar masses today.


Closest to Gamma2 is the bright (apparent magnitude +4.3) Gamma1 Velorum (Gamma Velorum B), a blue-white subgiant B star. Gamma1 lies 41.2 arcseconds from the Wolf-Rayet binary, a separation easily resolvable with binoculars. Gamma Velorum also has several fainter companions. Gamma Velorum C, a white A star (magnitude +8.5) is separated by 62.3 arcseconds from Gamma2, while the binary pair Gamma Velorum D and E lies 93.5 arcseconds away . The D component is another A star (magnitude of +9.4); its companion is a 13th magnitude star, separated by 1.8 arcseconds.


Gamma2 Velorum may be a member of the Vela OB2 association of stars


Gamma2 Velorum
visual magnitude 1.75
absolute magnitude -5.31
spectral type WR8 + O7.5Ie
distance 840 light-years (258 pc)
position RA 08h 09m 32.00s, Dec -47° 20' 12.0"
other designations Regor, Suhail, Suhail Al-Muhlif, HR 3207, CD -46°3846/3847, HD 68273, SAO 219504, FK5 309, GC 11105, HIP 39953


Components of the Gamma Velorum system
component separation
position angle
with respect to
(other component)
A (Gamma2) HD68273       1.83
B (Gamma1) HD68243 41.2 220 A 4.27
C 62.3 151 A 8.2
D 93.5 141 A 9.1
E 1.8 146 D 12.5