See the Music - Cygnus Loop's Supersonic Shockfronts
See the Music – Supernova Supersonic Shockfront Symphony in Cygnus
Askar FRA500; iOptron HEM27;
ASI6200MM, - Antlia Pro 3.5nm Narrowband Filters
2x1 Mosaic
H,O,S : (73,68,55 x 780s Bin 1, Gain 100)
Total integration time = 42.5 hrs (July 9 to 17) Maple Bay, BC
They Cygnus Loop is a large spheroidal supernova remnant. What one is really looking at are the supersonic shockfronts that originated from a violent supernova explosion between 5000 to 8000 years ago and just 1500 light years away. The supernova itself would have been visible to the naked eye just a civilizations were beginning to appear on earth. People wouldn’t have heard it though, as it will take a long time for the sound to reach us – sound is quite slow in space although the supernova pressure blast travels much faster. Being closer and younger that other supernova remnants in the sky, it is quite bright for the camera.
What the supersonic blast does is create a spherical balloon like bubble, with the actual balloon surface made up of both material originating from the supernova star and additional material swept up at the front as the balloon expands. The balloon of material is known as a shock front partly because there is no pressure warning to anything outside of the balloon that it is coming because it is travelling faster than sound (and partly because it sounds more scientific than balloon). Outside of the balloon, we can see wisps of material (hydrogen -dimly glowing red), but the region within the spheroid contains little – instead it has been swept up by the shock front..
But a simple balloon shape wouldn’t make that interesting a picture. The speed of the expanding shock front will vary depending upon the type and amount of material that it encounters as it expands. In addition, any condensed (non gaseous) material (dust, stars, planets) will cause the shock front to interfere with itself, cause additional mini-shock fronts to be created and even reflect upon itself – resulting in a complex pattern of shock fronts (look like tendrils in this 2-D image) that we see in this here. The colour of the tendrils is related to the substance emitting light at the shock fronts. Oxygen ion emits a blue colour, while hydrogen atoms and sulphur items emit red and orange. White are bright emissions, likely from all three. Aside from resembling a bass clef, my symphonic reference is to the speed of sound that controls the creation of the patterns of light and colours seen.
The colour variation may be a result of difference in composition of the tendril. This would be convenient if it were, as a rocket ship could mine its own fuel (oxygen from the blue portions, and hydrogen from the red) while being very careful not to mix the two. Alternatively – higher energy UV light is required to ionize and power the oxygen emissions while ionizing hydrogen which is invisible.
Where the UV light is less energetic it may be insufficient to ionize oxygen and only partly ionize or excite hydrogen atoms such that it can glow red as its electrons changes orbitals.
Another question I have is the source of the UV light energize. It is the remains of the star that went supernova? Alternatively is it the heat generated in the shock front itself due to internal friction and compression involved in supersonic travel. Or is it the result of neighbourhood stars? Maybe all of the above.
This isn't my first "Cygnus Loop", but I think it is my best.
