Gamma Velorum is a quadruple

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Vela. This name is the

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

for the star, which is Latinised from γ Velorum and abbreviated γ Vel. At a combined magnitude of +1.7, it is one of the brightest stars in the night sky, and contains by far the closest and brightest Wolf–Rayet star. It has the traditional name Suhail al Muhlif and the modern name Regor , but neither is approved by the International Astronomical Union. The γ Velorum system includes a pair of stars separated by 41″, each of which is also a spectroscopic binary system. γ² Velorum, the brighter of the visible pair, contains the Wolf–Rayet star and a blue supergiant, while γ¹ Velorum contains a

blue giant In astronomy, a blue giant is a hot star with a luminosity class of III (giant star, giant) or II (bright giant). In the standard Hertzsprung–Russell diagram, these stars lie above and to the right of the main sequence. The term applies to a ...

and an unseen companion.

Distance

Gamma Velorum is close enough to have accurate parallax measurements as well as distance estimates by more indirect means. The ''

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial obj ...

'' parallax for γ² implies a distance of 342 parsecs (pc). A dynamical parallax derived from calculations of the orbital parameters gives a value of 336 pc, similar to spectrophotometric derivations. A VLTI

interferometry Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

measurement of the distance gives a slightly larger value of 368 ± 51 pc. All these distances are somewhat less than the commonly assumed distance of 450 pc for the Vela OB2 association which is the closest grouping of young massive stars.

Stellar system

The Gamma Velorum system is composed of at least four stars. The brightest member, γ² Velorum or γ Velorum A, is a

spectroscopic binary A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...

composed of a blue supergiant of spectral class O7.5 (), and a massive Wolf–Rayet star (, originally ). The binary has an orbital period of 78.5 days and separation varying from 0.8 to 1.6 astronomical units. The Wolf–Rayet star is likely to end its life in a Type Ib supernova explosion; it is one of the nearest supernova candidates to the Sun. The Wolf–Rayet star has traditionally been regarded as the primary since its emission lines dominate the spectrum, but the O star is visually brighter and also more luminous. For clarity, the components are now often referred to as WR and O. The bright (apparent magnitude +4.2) γ¹ Velorum or γ Velorum B, is a spectroscopic binary with a period of 1.48 days. Only the primary is detected and it is a blue-white giant. It is separated from the Wolf–Rayet binary by 41.2″, easily resolved with

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

. The pair are too close to be separated without optical assistance, and they appear to the naked eye as a single star of apparent magnitude 1.72 (at the average brightness of γ² of 1.83). Gamma Velorum has several fainter companions that share a common motion and are likely to be members of the Vela OB2 association. The magnitude +7.3 CD-46 3848 is a white F0 star at is 62.3 arcseconds from the A component. At 93.5 arcseconds is another binary star, an F0 star of magnitude +9.2. Gamma Velorum is associated with several hundred pre-main-sequence stars within less than a degree. The ages of these stars would be at least 5 million years.

Etymology

The Arabic name is al Suhail al Muḥlīf. al Muhlif refers to ''the oath-taker'', and al Suhail is originally derived from a word meaning ''the plain''. Suhail is used for at least three other stars: Canopus,

λ Velorum ) Lambda Velorum (λ Velorum, abbreviated Lambda Vel, λ Vel), officially named Suhail , is a star in the southern constellation of Vela. With a mean apparent visual magnitude of 2.21, this is the third-brightest star in the constellat ...

(al Suhail al Wazn) and

ζ Puppis Zeta Puppis (ζ Puppis, abbreviated Zeta Pup, ζ Pup), formally named Naos , is a star in the constellation of Puppis. The spectral class of O4 means this is one of the hottest, and most luminous, stars visible to the ...

(Suhail Hadar).

Suhail ) Lambda Velorum (λ Velorum, abbreviated Lambda Vel, λ Vel), officially named Suhail , is a star in the southern constellation of Vela. With a mean apparent visual magnitude of 2.21, this is the third-brightest star in the constellati ...

is also a common Arabic male first name. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

, (), meaning '' Celestial Earth God's Temple'', refers to an asterism consisting of γ² Velorum,

δ Velorum Delta Velorum (δ Velorum, abbreviated Delta Vel, δ Vel) is a triple star system in the southern constellation of Vela, near the border with Carina, and is part of the False Cross. Based on parallax measurements, it is approxima ...

, κ Velorum and b Velorum. Consequently, γ² Velorum itself is known as (), "the First Star of Celestial Earth God's Temple". The name Regor ("Roger" spelled in reverse) was invented as a practical joke by the Apollo 1 astronaut Gus Grissom for his fellow astronaut Roger Chaffee.Apollo 15 Lunar Surface Journal
''Post-landing Activities''
commentary at 105:11:33 Due to the exotic nature of its spectrum (bright emission lines in lieu of dark

absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s) it is also dubbed the ''Spectral Gem of Southern Skies''.

References

{{DEFAULTSORT:Gamma Velorum O-type giants B-type giants Wolf–Rayet stars Spectroscopic binaries 6 Gum Nebula Vela (constellation) Velorum, Gamma 3207 Durchmusterung objects 068273 039953 Regor TIC objects

Distance

Stellar system

Etymology

See also

References