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VELA

The Sail

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Argo Navis - Uranographia by Johannes Hevelius - 1687

Vela is a southern constellation not visible in its entirety above 30 degrees north latitude. Its name is Latin for sail, as it was once part of the much larger constellation, Argo Navis, which represented the stern section of the Argos, the legendary ship that transported Jason and the Argonauts on their quest to find the Golden Fleece. The Hevelius depiction of Argo Navis above is reversed, as if looking down from space at the outside of a globe or spherical shell of stars that surrounded Earth, as the ancients believed.

In 1751, during his famous expedition to South Africa to chart the southern skies, French astronomer Nicolas Lacaille decided the ancient constellation was just too large and unwieldy. There were too many stars, and too many other, mysterious objects. The area needed to be divided into smaller, more manageable constellations. But the Argo Navis was such a majestic, traditional image it couldn't simply be scrapped and replaced by new constellations. So Lacaille compromised, and left the ancient image in the sky, with all its grand mythological romance, and simply divided the figure into three parts: Puppis, the poop deck, Vela, the sail, and Carina, the keel.

Lacaille did not, however, tamper with the original Bayer Designations (Greek letter hierarchy according to brightness) of the stars in Argo Navis. This means that each of the new constellations does not necessarily have its own alpha, beta, gamma star etc., but uses the original designations assigned to the entire Argo Navis.

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Argo Navis - Uranometria by Johann Bayer - 1603

In the image above of the Argo Navis passing through the "Clashing Rocks", I have taken the liberty of tracing the new constellations over the magnificent artwork of Johann Bayer's 1603 Uranometria, to help show their ancient origins.

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Vela - April 1, 10:00 PM - Latitude 15° North, Longitude 95° West





Stars of Vela

Al Suhail al Muhlif (RA: 08h09m31.941s DE:-4720'11.56")

The brightest star in Vela is Gamma Velorum, known by the ancient Arabic name of Al Suhail al Muhlif, which Allen translates as the glorious oath. Appearing as one star to the naked eye, it resolves into two stars through binoculars or a small telescope.

The brighter of the Gamma Velorum pair is the primary star, Gamma Velorum A, or HD 68273, with a magnitude of 1.78. Spectroscopic analysis has shown Gamma Velorum A is itself a binary system with two monstrous stars that orbit each other too closely to be resolved visually. They are only 1 AU apart (Earth - Sun distance), orbiting each other every 78 days, and they are both much larger and hotter than our Sun. One is an 07I blue supergiant, 25 times more massive than the Sun, with a surface temperature of 35,000 K (the Sun is 6,000 degrees). The other is classified as a Wolf-Rayet type C8 (WC8) star, 10 times more massive than the Sun with a surface temperature of 60,000 K. (Wolf-Rayet stars are rare, super massive, super hot stars whose radiation overpowers their gravity, and causes them to continuously vent gas and dust into space. This quickly reduces their mass, and makes them very short lived, usually only a few million years).

The dimmer of the Gamma Velorum pair is the companion star, Gamma Velorum B, or HD 68243. It is a B2 blue/white subgiant, with a magnitude of 4.27. But the story does not end here. There are three fainter, more distant companions, Gamma Velorum C, D, and E, giving the entire Gamma Velorum system a total of six stars, all located about 1,000 light years away.

Al Suhail (RA: 09h07m59.727s DE:-4325'57.11")

The only other named star in Vela is Lambda Velorum, named Al Suhail, an old Arabic title meaning glorious or beautiful. It is a K4I orange supergiant, with a magnitude of 2.21, about 550 light years away.

Planets of Vela

HD 85512 (RA: 09h51m07.698s DE:-4330'17.21")

There are four stars in Vela known to support planetary systems. All but one of the planets discovered so far have been massive gas giants that orbit too close to their sun to have much chance of hosting any kind of life.

However, in September, 2011, the European Southern Observatory in Chile discovered a planet orbiting star HD 85512, a K6V orange main sequence star that has the potential to harbour life. The planet is named HD 85512b, and it is only 3.6 times the size of Earth, one of the smallest exoplanets found so far. Most significantly, this planet resides in the "habitable zone", also known as the "Goldilocks zone" (not too hot, not too cold). In other words, it orbits at just the right distance from its sun to allow for the existence of liquid water, an essential element for the evolution of life (as we know it). The planet has a balmy surface temperature of 77 degrees F (25 degrees C), and is relatively close to us at a distance of 35 light years. Unfortunately, its magnitude of 7.66 puts it out of visual range, although quickly found with a small telescope.

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HD 85512b Planetary System - ESO Artist Impression - September, 2011

Deep Skies of Vela

NGC 3132 - The Southern Ring Nebula (RA: 10h07m00.0s DE:-4026'00")

Sitting as it does, right in the middle of the Milky Way, the constellation Vela is an extremely busy place, full of nebulae and star clusters. One of the best targets in Vela for a small telescope is NGC 3132, also known as the Southern Ring Nebula, for its resemblance to the Ring Nebula in the northern constellation of Lyra. It's also referred to as the Eight-Burst Nebula, as it can appear like a figure eight in a small telescope. The nebula is located 2,000 light years from Earth and has an apparent magnitude of 8.2. In the Hubble photo below it is the dimmer of the two stars in the center of the nebula that collapsed and blew away its outer layers to form the nebula. It is a very hot, very dense little white dwarf, emitting enough ultraviolet radiation to cause the expanding cloud of gas around it to glow.

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NGC 3132 - Eight-Burst / Southern Ring Nebula - Hubble Space Telescope - November, 1998

NGC 3201 (RA: 10h17m 36.0s DE:-4625'00")

An even better target for a small scope is the globular cluster NGC 3201. It's 16,000 light years away, and has an apparent magnitude of 6.8.

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NGC 3201 - Globular Cluster - European Southern Observatory - February, 2010

NGC 2547 (RA: 08h10m 12.0s DE:-4912'00")

The open star cluster NGC 2547 is also a nice sight through a small scope. It's 2,000 light years away, and has an apparent magnitude of 4.7.

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NGC 2547 - Open Star Cluster - European Southern Observatory - March, 2013

Vela Supernova Remnant (RA: 08h35m20.66s DE:-4510'35.20")

Moving into the domain of time exposures and nebula filters and large telescopes, we find the famous Vela Supernova Remnant. At the heart of this huge, expanding cloud of gas is the Vela Pulsar, the super dense core of the super massive star that exploded over 10,000 years ago, and created the supernova remnant. The Vela Supernova Remnant is large, 114 light-years (35 parsecs) across, but it is only a small part of a truly immense nebula known as the Gum Nebula (after astronomer Colin Gum, who discovered it in 1952). The Gum Nebula is the largest nebula in the sky and stretches over 800 light years across Vela into the constellation of Puppis. It is considered to be the remnant of a supernova that occurred about one million years ago. It is so large and so faint, its image can only be captured with wide field optics, special filters, and very long exposures.

The photo below shows a portion of the Vela Supernova Remnant, containing the Pencil Nebula (NGC 2736), considered to be part of the initial shock wave of the Vela supernova that encountered a thick cloud of dust as it expanded. You can clearly see other blue colored filaments of the Vela Supernova Remnant just above it, and the huge clouds of red hydrogen gas from the much larger Gum Nebula all around it.

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Portion of Vela Supernova Remnant - European Southern Observatory - September, 2012

The Pencil Nebula (RA: 09h00m 24.0s DE:-4554'00")

Below is a close-up view of the Pencil Nebula, looking more like a witch's broom, captured in exquisite detail from the European Southern Observatory in Chile. The Pencil Nebula is 0.75 light years long, or about 4.5 trillion miles, a thousand times the distance between Earth and the dwarf planet Pluto (4.5 billion miles).

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NGC 2736 - The Pencil Nebula - European Southern Observatory - September, 2012

The Vela Pulsar (RA: 08h35m20.66s DE:-4510'35.20")

NASA's Chandra X-ray Observatory, orbiting 86,500 miles (138,000 km) above us, has confirmed that the star that blew up 10,000 years ago and created the Vela Supernova Remnant is anything but dead. It has collapsed and transformed itself into a neutron star, one of the densest known objects in the Universe. One teaspoon of matter from a neutron star would weigh about one billion tons. This neutron star is about 12 miles in diameter, and spinning at a rate of 11 times a second, faster than a helicopter rotor. This rapid rotation sends out powerful pulses of electromagnetic radiation along the axes of rotation. When the axes are oriented towards Earth, the pulses can be identified, and the neutron star is reclassified as a pulsar.

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Vela Pulsar - Chandra X-ray Observatory - January, 2013







Winter: Orion   Canis Major   Canis Minor   Monoceros   Lepus   Eridanus   Taurus   Auriga   Camelopardalis   Lynx   Gemini   Cancer  
Spring: Hydra   Sextans   Crater   Corvus   Leo   Leo Minor   Ursa Major   Ursa Minor   Canes Venatici   Coma Berenices   Virgo   Bootes  
Summer: Draco   Corona Borealis   Hercules   Ophiuchus   Serpens   Libra   Scorpius   Sagittarius   Scutum   Aquila   Sagitta   Vulpecula   Lyra   Cygnus  
Autumn: Andromeda   Perseus   Pegasus   Cassiopeia   Cepheus   Cetus   Lacerta   Delphinus   Equuleus   Capricornus   Aquarius   Pisces   Aries   Triangulum  
Southern Skies: Centaurus   Crux   Lupus   Corona Australis   Piscis Australis   Sculptor   Tucana   Fornax   Dorado   Columba   Puppis   Carina   Vela  

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