| Synopsis: Multiple
star (5 visual components); located in Vela; R.A. 08:09:31.965, dec. -47:20:11.91;
culmination ???; magnitude 1.83 (variable); distance ??? (parallax) – ??? (Ridpath
& Tirion) pc (approx. 192 to 650 light years).
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HD ???; double star; located in Vela; R.A. ???, dec. -???; magnitude ???; distance 258 pc (approx 840 light years)..... | |||||||||||||||||||||||||||||||||||
| Description: Star – Introduction/Components Gamma Velorum is a famous visual multiple comprising a brilliant Wolf-Rayet primary, possibly the nearest such star to us, and an unrelated (???check???) magnitude 4, type B companion (g 1 Velorum). There are two wide companions, the more distant itself having a very close companion bringing the complement to five. Finally, the primary itself is a spectroscopic binary, the unseen component being a giant type O7 star. |
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Star M/L/Spectrum The brightest component of the Gamma Velorum multiple, g 2, is the spectroscopic binary of Wolf-Rayet and O stars (WC8+O7.5e). These two objects have masses of 17 and 32 M respectively (the W-R star is the lighter and brighter of the pair) and an orbital period of 78 days. The effective surface temperature of the W-R component is given by Böhm-Vitense 1989, p. 59, as 29,000 ± 3000 K. |
A close double WR+O; one of the few Wolf-Rayet stars readily
identifiable with the naked eye. ... the distance 227 (258) 299 pc (~840 light years). Single star evolutionary modelling suggests an age of 3.5 (4.0) 4.8 Myr for the O star component. (Schaerer et al. 1998.) The brightness of the O star is typical for a giant. Conti & Smith 1972 considered the O star might be a supergiant, on the basis of the compositional ratio of Si IV:He I. However, the fast rotation of the O star and the spectrum of the WR star "blend" individual spectral lines, making the measurements difficult, and this interpretation is now believed doubtful. |
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| Property | Value | Notes/References |
| SAO Number | ||
| HD Number | ||
| R.A. | ||
| Declination | ||
| Precession in RA | ||
| Precession in dec. | ||
| Proper Motion RA | ||
| Proper Motion dec | ||
| Radial Velocity | ||
| Parallax | 3.88±0.53mas | |
| Distance | 258 pc | |
| mv | ||
| Mv | -5.5 -5.24 – -5.2 -3.84 – -3.43 |
WR+O O star WR star |
| M/M¤ | 29.5±15.9 22±4 7.7±1.5 |
WR+O O star WR star |
| L/L¤ | 200,000 50,000 |
O star (log L/L¤ =
5.3±0.15) WR star (log L/L¤ = 4.7±0.2) |
| B-V | ||
| U-B | ||
| V-R | ||
| R-I | ||
| b-y | ||
| m1 | ||
| c1 | ||
| Hbeta | ||
| Spectral Type | WC8+O8III | |
| R/R¤ | ||
| Teff | 34,000±1500K | O star |
| Rotational Velocity | 220 km/s | O star |
| Period (days) | 78.5002±0.0001 | |
| Table 1: Known Parameters for Gamma2
Velorum Notes: Proper motion in R.A. includes the cos(dec) term (After Schaerer et al. 1997 except where otherwise noted.) |
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| Gamma2 Velorum may be a member of the Vela OB2 association of stars (Sahu 1992, Schaerer et al. 1997). |
| Observation: Easily seen with the naked eye. g Vel is an easy double in any small telescope (and possibly even in good binoculars). |
Böhm-Vitense, Erika (1989b): Introduction to Stellar Astrophysics. Volume 2 – Stellar Atmospheres. Cambridge.
Conti, P; Smith, L.F. (1972): Astrophysical Journal, 172:623.
Howarth, Ian D.; Prinja, Raman K.; Massa, Derck (1995): The IUE MEGA Campaign: The Rotationally Modulated Wind of z Puppis. The Astrophysical Journal, 452:L65-L68, 10 October 1995.
Ochsenbien, F.; Acker, A.; Legrand, E.; Poncelet, J.M.; Thuet-Fleck, E. (1988): Le catalogue des etoiles les plus brilliantes. NASA Astronomical Data Centre, catalogue 5053.
Sahu, M. (1992): Unpublished PhD thesis, cited in Schaerer et al. (1997).
Schaerer, Daniel; Schmutz, Werner; Grenon, Michel 1997: Fundamental Stellar Parameters of z Pup and g2 Vel from HIPPARCOS Data. ApJ Letters 484: L153-156.
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