Sail (constellation)
Sailing is an austral constellation, one of the four parts into which the constellation of Argo Navis (the ship Argos) was divided, the others being Carina (the keel), Puppis (the stern) and Pyxis (the compass).
Notable features
Vela shares the Bayer name of its stars with the other three constellations that were part of the Argo Navis, so it does not have α or β stars. Its brightest star, at magnitude 1.75, is γ Velorum, a six-fold star system containing the brightest Wolf-Rayet star in the sky. This is a very hot evolved star—its surface temperature is about 70,000 K—and it is one of the closest supernova candidates to Earth. Another component of the system is a blue star of the spectral type O7.5, 180,000 times more luminous than our Sun. γ Velorum is located 1235 ± 13 light years from the solar system.
The second brightest star in Vela is δ Velorum, officially called Alsephina, a triple star system 80 light-years away that contains an eclipsing binary with an orbital period of 45.15 days.
λ Velorum, known as Suhail, is the third brightest star in the constellation; It is an orange star classified between a luminous giant and a supergiant, with a radius 207 times larger than that of the Sun and slightly variable. Next in brightness is κ Velorum, a bluish-white star of spectral type B2IV-V with a luminosity equivalent to that of 18,400 suns. Like δ Velorum, it is also a spectroscopic binary.
δ Velorum and κ Velorum, together with Avior (ε Carinae) and Aspidiske (ι Carinae), form the False Cross asterism, an enlarged but fainter version of the Southern Cross.
μ Velorum is also a binary, made up of a yellow giant of spectral type G6III and a dimmer companion of type F4V or F5V, with an orbital period between 116 and 138 years. Another interesting star is φ Velorum, known by its Chinese name Tseen Ke; It is a distant blue supergiant—it is about 1,600 light-years away—of type B5Ib with a luminosity similar to that of κ Velorum.
Much closer to us, at 61 light years, ψ Velorum is a binary whose components, of type F0V and F3V, complete an orbit around the common center of mass every 33.95 years. Likewise, p Velorum is a triple system composed of two stars of type F3IV and F0V that move at short distances —its orbital period is 10.21 days— and a white star of the main sequence of type A6V that uses 16.54 years to orbit around the inner pair.
Vela contains several Cepheids such as S Velorum or AH Velorum. The first oscillates between magnitude 7.74 and 9.5 over a period of 5.9336 days, while the second oscillates between 5.50 and 5.89 every 4.2271 days. AI Velorum, prototype of a group of pulsating stars called AI Velorum variables, is also located in this constellation. Its variability was detected in 1931 by Ejnar Hertzsprung. Another variable of interest is V390 Velorum, a star in evolution from the red giant phase to the white dwarf phase, a transition in which the expulsion of a large envelope of gas and dust gives rise to the formation of a planetary nebula.
Another variable of interest is KQ Velorum, a chemically peculiar star whose spectrum shows peculiarities in the europium, chromium, and silicon bands. Classified as the Alpha2 Canum Venaticorum variable, it is accompanied by a neutron star of more than two solar masses. IM Velorum has similar characteristics, whose surface shows areas enriched in lithium, europium and oxygen.
Vela contains several stars with exoplanets. HD 75289 is a yellow dwarf slightly hotter than the Sun that has a planet whose mass is at least 42% of the mass of Jupiter; Said planet moves very close to the star, completing an orbit in only 3 and a half days. Around another yellow dwarf, HD 93385, two super-Earth-type planets have been discovered that complete an orbit every 13.2 and 46 days respectively. HD 83443 —called Kalausi according to the IAU—, is a metal-rich K0V orange dwarf with a planet that also orbits very close to its star, just 11% of the distance between Mercury and the Sun. With similar characteristics is HD 85390 —called Natasha—, around which a planet with a minimum mass equivalent to 42 Earth masses has been discovered. Gliese 370 (HD 85512) is another somewhat cooler dwarf—spectral type K5V—with one planet, HD 85512 b, that may be Earth-like in terms of habitability. Finally, the exoplanet WASP-19b is located in this constellation, discovered in 2009, notable for having the shortest orbital period among all known planets: 0.789 days or 18.9 hours.
Also in Vela is Luhman 16 (WISE 1049-5319), a binary system composed of two brown dwarfs only 6.6 light-years from the solar system. The masses of both components are 34 and 28 times greater than that of Jupiter; the separation between them is 3.5 AU, with an orbital period of approximately 27 years.
450 parsecs distant, HH 46/47 is a complex of Herbig-Haro objects in a globule of Bok near the Gum Nebula. Jets of partially ionized gas emerging from the young star produce visible shocks upon impact with the surrounding medium. Discovered in 1977, it is one of the most studied Herbig-Haro objects.
Another interesting object is the Vela Pulsar: the optical identification of this pulsar associated with the Vela Supernova Remnant constituted direct proof of the relationship between supernovae and pulsars. It is the brightest pulsar in the sky at radio frequencies and it rotates at a rate of 11,195 times per second. Its surface temperature reaches 660,000 K. Likewise, Vela X-1 is a high-mass X-ray binary composed of a pulsar and a B-type blue supergiant with a mass equivalent to 23 solar masses. The system is located approximately 2 kiloparsecs from Earth.
NGC 3132, known as the Southern Ring Nebula, is a bright planetary nebula of apparent magnitude +9.87; images obtained with the Hubble Space Telescope show two stars near its center, one bright (magnitude +10.1) and one dimmer. NGC 2792 is another planetary nebula in Vela: it is nearly circular in shape and lies at a distance between 1,400 and 3,200 parsecs.
Several open clusters can be observed in Vela. IC 2391 occupies an area of about 50 arc minutes and contains about 30 stars, ο Velorum being the brightest among them. Another cluster, NGC 2547, is considered a young cluster of about 30 million years old. In contrast, NGC 3201 is a globular cluster discovered by James Dunlop in 1826. The stellar population of this cluster is not homogeneous, a very unusual feature in clusters, with the cool, red stars tending to be closer to its core.
RCW 36 is a star-forming region that has given rise to several hundred young stars that illuminate an HII region. It is approximately 700 parsecs distant from the solar system.
Main Stars
- γ Velorum (Regor or Suhail Al Muhlif), the brightest star of constellation with magnitude 1.75. It is a star system whose main component (γγ)2 Velorum) is the brightest and closest Wolf-Rayet star.
- δ Velorum (Alsephina), second brightest star with magnitude 1,95 is a star system formed by an eclipsing binary star and a white-yellow dwarf.
- κ Velorum (Markeb), of magnitude 2,47, white-azulada subgiant star.
- λ Velorum (Suhail or Alsuhail), third brightest star of the constellation with magnitude 2,23, an orange supergiant at 570 light years.
- μ Velorum, of magnitude 2,69, binary star formed by a yellow giant and a yellow dwarf. In 1998, the Extreme Ultraviolet Explorer space telescope detected a strong call from the main star that lasted two days.
- ο Velorum, the brightest star of the IC 2391 cluster, also called the Omicron Velorum cluster.
- φ Velorum (Tseen Ke), of magnitude 3,52, white-azulada supergigante at almost 2000 light years away.
- Velorum, binary star with two separate white components 0.68 seconds of arc.
- C Velorum (HD 73155), distant bright orange giant of magnitude 4,99.
- L Velorum (HD 83058), a blue sub-gigant and a "fugitive star" that appears to come from the IC 2602 cluster.
- M Velorum (HD 83446) and q Velorum (HD 88955), white stars of the main sequence of magnitude 4,35 and 3,84 respectively.
- N Velorum (HD 82668), orange giant of magnitude 3.13.
- O Velorum (HD 84461), white star of magnitude 5.55.
- e Velorum (HD 73634), white luminous giant of magnitude 4,17.
- i Velorum (HD 95370), white subgiant of magnitude 4.38.
- k Velorum (HD 79940), white-yellow giant of magnitude 4.64.
- p Velorum (HD 92139 / HD 92140), triple to 86 light years.
- AI Velorum, pulsating variable star prototype of a group of variables bearing its name (variables AI Velorum).
- S Velorum and CV Velorum, nearby eclipsant binaries with periods of 5,934 and 6,889 days respectively.
- V Velorum, cefeida whose brightness varies between magnitude 7,19 and 7,95 with a period of 4,371 days.
- GZ Velorum, luminous orange and irregular variable of average magnitude 4.58.
- IM Velorum, variable Alpha2 Canum Venaticorum of rapid oscillations; next to the main period of 2,85 days the star shows pulses every 11,67 minutes.
- IW Velorum, Delta Scuti variable of magnitude 5.91.
- KQ Velorum, chemically peculiar star and variable Alpha2 Canum Venaticorum.
- KX Velorum, blue giant and eclipsing binary.
- LR Velorum, distant white-azulada supergiant 60,000 times brighter than the Sun.
- LU Velorum, binary composed of two red dwarfs of type M3.5.
- MX Velorum, Star Be member of the star association Vela OB2.
- PT Velorum, an eclipsing binary whose period is 1,802 days.
- V390 Velorum (IRAS 08544-4431), binary system whose primary is in a rapid transition phase from red to white dwarf giant; the system is surrounded by a circum-stellar disk.
- HD 75289 (HR 3497), yellow dwarf with an extrasolate planet.
- HD 83443 and HD 85390, orange dwarfs with planetary systems; HD 83443 b moves in an orbit very close to the star.
- Gliese 320 and Gliese 370 (HD 85512), two orange dwarfs distant from each other 8.6 light years. Both are more than 36 light years from the Solar System and the second one has an extrasolar planet.
- CPD-57 2874 (CD-57 3107), ancient blue supergiant that is beginning to get off from its outer wrap.
- Vela X-1, high-mass X-ray binary formed by supergiant HD 77581 and a pulp.
Deep Sky Objects
- Planetary Nebula NGC 3132, known as the Southern Ring Nebula, is located on the border with Antlia. It is considered the southern version of the Lyra Ring Nebula. It has a diameter of 0.5 light years and is 2000 light years from Earth. In its center two stars can be observed: the faintest of the two, of magnitude 16, is the white dwarf responsible for the formation of the nebula.
- NGC 2792, almost circular planetary nebula. The central star has an approximate temperature of 130 000 K.
- NGC 2899, also a planetary nebula, was discovered by John Herschel in 1835.
- Resto de supernova de Vela, in whose center is the Pulsar de Vela, the first to be optically identified. It is about 815 light years away and it is thought that the parent star exploded 11 000 - 12 300 years ago. The Pencil Nebula (NGC 2736) is part of the rest of the supernova.
- Resto de supernova Vela Jr—or simply Vela Junior—, one of the most studied objects of his class throughout the electromagnetic spectrum.
- SNR G272.2-03.2, rest of supernova that barely broadcasts in radio frequencies.
- Nebulosa Gum, an emission nebula that is difficult to distinguish; it is thought that it also corresponds to a supernova remnant, although very expanded, from an explosion that occurred about a million years ago.
- Gum 19, star-lit star formation region V391 Velorum.
- IC 2391 or Omicron Cluster Velorum is an open cluster visible to the naked eye. It consists of thirty stars.
- NGC 2547, young open cluster with an approximate age of 20 to 35 million years.
- NGC 3201, distant globular cluster 16 300 years from Earth.
- Herbig-Haro HH 47 object; in this case, nebulosity is associated with a newly formed star.
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