The Vela Constellation

Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis. Vela is bordered by Antlia and Pyxis to the north, Puppis to the northwest, Carina to the south and southwest, and Centaurus to the east. Covering 500 square degrees, it ranks 32nd of the 88 modern constellations in size. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between  08h 13.3m and  11h 05.5m, while the declination coordinates are between −37.16° and −57.17°.

The brightest star in the constellation, Gamma Velorum, is a complex multiple star system. The brighter component, known as Gamma2 Velorum or Suhail, shines as a blue-white star of apparent magnitude 1.83. It is a spectroscopic binary made up of two very hot blue stars orbiting each other every 78.5 days and separated by somewhere between 0.8 and 1.6 AU. The brighter component is a hot blue main-sequence star of spectral type O7.5 and is around 280,000 times as luminous, is around 30 times as massive and is 17 times the diameter of our Sun with a surface temperature of 35,000 K. The second component is an extremely rare example of hot star known as a Wolf–Rayet star, and is the brightest example in the sky. It has a surface temperature of 57,000 and is around 170,000 times as luminous as our sun, though it radiates most of its energy in the ultraviolet spectrum. Gamma1 is a blue-white star of spectral type B2III and apparent magnitude 4.3. The two pairs are separated by 41 arcseconds. Parallax measurements give a distance of 1,116 light-years, meaning that they are at least 12,000 AU apart. Further afield are 7.3-magnitude Gamma Velorum C and 9.4-magnitude Gamma Velorum D, lying 62 and 93 arcseconds south-southeast from Gamma2. The next brightest star is Delta Velorum or Alsephina, also a multiple star system and one of the brightest eclipsing binaries in the sky. Together with Kappa Velorum or Markeb, Iota Carinae or Aspidiskeand Epsilon Carinae or Avior, it forms the diamond-shaped asterism known as the False Cross—so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation. Appearing as a white star of magnitude 1.95, Delta is actually a triple or possibly quintuple star system located around 80 light-years from the Solar System. Delta A has a magnitude of 1.99 and is an eclipsing binary composed of two A-type white stars (Delta Aa and Ab) which orbit each other every 45.2 days and lie 0.5 AU from each other, with a resulting drop in the magnitude of 0.4 when the dimmer one front of the brighter. Delta B is a 5.1 magnitude yellow G-class star of similar dimensions to our sun which ranges between 26 and 72 AU away from the brighter pair, taking 142 years to complete a revolution. Further out still, at a distance of 1700 AU, are two red dwarfs of magnitudes 11 and 13. If they are part of the multiple systems, they take 28000 years to complete an orbit. The orange-hued Lambda Velorum, or Suhail, is the third-brightest star in the constellation. A supergiant of spectral type K4Ib-II, it varies between magnitudes 2.14 and 2.3 and lies 545 light-years distant. It has around 11,000 times the luminosity, 9 to 12 times the mass and 207 times the diameter or our sun.

The discovery of a binary brown dwarf system named Luhman 16 only 6.6 light-years away, the third-closest system to the Solar System, was announced on 11 March 2013.

Of the deep-sky objects of interest in Vela is a planetary nebula known as the NGC 3132, nicknamed the ‘Eight-Burst Nebula’ or ‘Southern Ring Nebula.’ It lies on the border of the constellation with Antlia. NGC 2899 is an unusual red-hued example. This constellation has 32 more planetary nebulae. The Gum Nebula (Gum 12) is a faint emission nebula, believed to be the remains of a million-year-old supernova. Within it lie the smaller and younger Vela Supernova Remnant. This is the nebula of a supernova explosion that is believed to have been visible from Earth around 10,000 years ago. The remnant contains the Vela Pulsar, the first pulsar to be identified optically. Nearby is NGC 2736, also known as the Pencil Nebula. HH-47 is a Herbig-Haro Object, a young star around 1,400 light-years from the Sun that is ejecting material at tremendous speed (up to a million kilometres per hour) into its surrounds. This material glows as it hits surrounding gas. Gum 19 is a star-forming region in Vela, approximately 22,000 light years from Earth. The nebula is illuminated by the large, hot blue supergiant star V391 Velorum. The star has a surface temperature of 30,000 degrees Celsius. NGC 2670 is an open cluster located in Vela. It has an overall magnitude of 7.8 and is 3,200 light-years from Earth. The stars of NGC 2670, a Trumpler class II 2 p and Shapley class-d cluster, are in a conformation suggesting a bow and arrow. Its class indicates that it is a poor, loose cluster, though detached from the star field. It is somewhat concentrated at its centre, and its less than 50 stars range moderately in brightness. Located 2 degrees south of Gamma Velorum, NGC 2547 is an open cluster containing around 50 stars of magnitudes 7 to 15. NGC 3201 is a globular cluster discovered by James Dunlop on May 28, 1826. Its stellar population is inhomogeneous, varying with distance from the core. The effective temperature of the stars shows an increase with greater distance, with the redder and cooler stars tending to be located closer to the core. As of 2010, is one of only two clusters (including Messier 4) that shows a definite inhomogeneous population. RCW 36 is a star-forming region in Vela, and one of the nearest sites of massive star formation. This star-forming region has given rise to a cluster of several hundred young stars that power an HII region. The star-forming region lies in Clump 6 in the Vela Molecular Ridge Cloud C1. Credit: Constellation Guide, Wikipedia.