Orion the Hunter

Orion photographed from our backyard

It has come around to that time of year when the constellation Orion at midnight peeps over our backyard fence to say hello.

Toot and I are very fond of Orion and for astronomers it contains a number of real treasures. Of course it is the other way up for my readers in the southern hemisphere!

Orion is host to a vast molecular cloud, parts of which, are visible to the naked eye and look spectacular through binoculars or a small telescope.

Parts of the molecular cloud shine because molecules of hydrogen gas are being ionised by infrared and ultraviolet radiation from new born stars.

An easily observable example in Orion is the so called Trapezium in M42 found in Orion's Sword which sits below the belt stars; Alnitak, Alnilam and|Mintaka.  The new born Trapezium Stars, recently created in the last million or so years by the gravitational collapse of cold hydrogen gas molecules, are radiating in the ultra-violet spectrum, ionizing the gas cloud and causing it to shine through the emission of photons.

(Above)The Trapezium photographed
from my backyard through my 5 inch refractor.
(Right) M41 data from ESO, photo put
together using Iris by me.

 

The constellation Orion contains a number of famous astronomical wonders including;

• The red super-giant and semi regular variable star Betelgeuse, which is entering the final phase of its life on the main sequence and will in the next  million years, go super-nova to finally end its days as a planetary nebula.  Betelgeuse has run out of hydrogen fuel and is now fusing helium to create carbon. It will work its way up the Periodic table fusing one element after another until it gets to the element iron and at this point it will explode in a cataclysmic type II super-nova.  Earth will be quite safe as Betelgeuse is estimated to be some 1300 light years distant. 
• The bright star Alnitak, the easternmost star in the Belt of Orion, shines ultraviolet light into the Flame Nebula and this knocks electrons away from the great clouds of hydrogen gas that reside there. Primarily,the glow results when the electrons and ionized hydrogen recombine. Additional dark gas and dust lies in front of the bright part of the nebula and this is what causes the dark network that appears in the center of the glowing gas. 
• The Horsehead Nebula  is a dark cloud of dust and gas and is a region in the Orion Nebula where star formation is taking place right now.  The area of the Orion Nebula containing the Horsehead is a stellar nursery. The darkness of the massive nebula is not explained by this dust and gas, but by the complex blocking of the light from stars behind it.  The Horsehead is only observable through large amateur telescopes and from dark sites.

Thanks to the European Southern Obsrvatory (ESO), Wikipedia and Sky and Telescope