Volans Flies the Southern Skies

Volans Flies the Southern Skies
Volans (the Flying Fish) flees from its predator Dorado (the Mahi Mahi) across the southern sky. They are among the dozen southern hemisphere constellations that Flemish astronomer Petrus Plancius (1552-1622) created. He intended the new constellations to fill in parts of the sky not visible to northern astronomers. The constellations were based on stellar observations by the navigators Pieter Dirkszoon Keyser and Frederick de Houtman.

Plancius showed the new constellations on a celestial globe, but their first depiction in a celestial atlas was in 1603 in Johann Bayer's Uranometria. Volans is shown there as Piscis Volans, but its name was later shortened.

The flying fish can jump out of the water and use their side fins like wings to glide through the air. They are a favorite food of the mahi mahi. Those who sailed in tropical waters would have seen the life and death contest of the mahi mahi in pursuit of the flying fish.

You can't see the constellation Volans further north than about 15°, but it's visible throughout the southern hemisphere from November through January. In some places, such as New Zealand, it's circumpolar, which means it can be seen at any time of the year. However Volans is a small dim constellation and there isn't much to see. You need a big telescope to see most of the objects of interest.

Stars and planets
The stars of Volans seem dim from Earth. Yet what we see is deceptive because there are a number of highly luminous stars in Volans. However they are very far away. None of the constellation's stars is within 100 light years of the Solar System, unless you count a white dwarf 35 light years away. A white dwarf is just the tiny remnant of a sunlike star that exhausted its nuclear fuel and collapsed.

Volans does contain two double stars that amateur astronomers like to observe, Gamma Volantis and Epsilon Volantis. The most attractive is Gamma Volantis, an orange star and its yellow companion that can be separated into a colorful pair in a small telescope. Epsilon Volantis is, in fact, a quadruple star system. Each visible star can has an invisible companion known only through studying the light spectrum.

As of January 2017 Volans was known to have two stars with a planet . They are of particular interest because they're similar in mass to the Sun. Unfortunately for those in search of habitable planets, both of the planets are gas giants. One of them (HD 76700 b) is a hot Jupiter, a type of planet that doesn't exist in the Solar System. That's a Jupiter-sized planet that orbits very close to its star. This one is so close it orbits in four days. (In the Solar System Mercury takes 88 days.)

The other planet HD 68402 b is over twice the distance from its star as Earth is from the Sun. Its year is just over three Earth years. It's outside the habitable zone of its star, but it could possibly have moons with microscopic life. (At its simplest, the habitable zone around a star is the area where bodies of liquid water could exist on the surface.)

Deep sky objects
There are a few interesting galaxies in Volans. The most notable one is the Lindsay-Shapley ring (AM0644-741), a ring galaxy 300 million light-years from Earth. Millions of years ago there was a galactic collision in which the cores of two galaxies merged into one – forming the core of older yellow stars shown in the picture. The shockwave triggered extensive starbirth, and the new stars expanded into a ring around the galaxy. These hot young stars are blue, and you can see in some regions the pink glow of the hydrogen gas energized by their ultraviolet light.

Another beautiful and unusual galaxy is NGC 2442, known also as the Meathook Galaxy. It's a spiral galaxy 50 million light-years from Earth, but it's strangely shaped with spiral arms of two different lengths. The longer arm, as in the pink regions of the ring galaxy, exhibits intense star formation with lots of hot young stars energizing the gas around them. A gravitational interaction with another galaxy in the distant past has pulled it out of shape and led to a high rate of star formation.

Dorado the predator
Volans has not ended up as lunch for the heavenly Dorado, although it's perilously close.

Dorado is the Portuguese word for a dolphinfish, of which mahi mahi is the most common type. The dolphinfish, by the way, is entirely unrelated to dolphins which are mammals. Mahi mahi are large – about a meter on average – and a beautiful fish. They're also quite tasty, so their own predators include humans.

In Johann Bode's celestial atlas Uranographia in 1801 Dorado was shown as Xiphias (the Swordfish). However it isn't a swordfish, even though that would make more sense than the lists which name it as a goldfish. I have trouble imagining the little things in fishbowls and ponds pursuing the flying fish through the tropical seas.

Like Volans, Dorado is a faint constellation, but it contains several known exoplanets and a proliferation of deep sky objects, most notably the Large Magellanic Cloud, a satellite galaxy of the Milky Way.

You Should Also Read:
Dorado the Mahi Mahi
ABC of Astronomy - D Is for Double Star
White Dwarfs

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