Jeff's Blog - Monday, October 9, 2017 - The Veil Nebula

Veil Nebula, or Cygnus Loop, see

Ed, a friend from my camera club, and I went out to a farmer's field near Wolcott Mill Metropark to play around with some astrophotography. Except for a couple rising-moon shots just before we packed up and left, this was my one-and-only image from that evening. If you'd like to enlarge the photo, click or tap it.

Off in a different region of the universe, at a moment about 6000 years ago a massive star near the center of this photograph exploded as a supernova. The stuff that formed all but the central core of that star was flung outward into space in a thin expanding bubble of superheated glowing gas. Just as we can more easily see the edge of a soap bubble than its center, we can see that star stuff, still glowing from the stupendous power of that explosion, along the edge of that bubble. The left edge of the bubble is the fairly bright arc on the left side of the photo; the right edge of the bubble appears to be lit up by the brightet star in the photo, and only small faint fragments of the top and bottom of the bubble are visible.

When that star exploded, urban cultures in Mesopotamia were developing the wheel, and the world-wide population of humanity was 5-7 million people, less than now live within the city limits of New York City. Over the subsequent 6000 years, the bubble has expanded out to a diameter of 90 light years, which is 20 times the distance from the sun to our next nearest star, Alpha Centauri. Projected onto our sky, the bubble is 3 degrees across, which is about 6 full-moon diameters.

The bubble is 1500 light years away from us, so the light we're looking at in this photo was emitted shortly after the fall of the Roman Empire, and a miniscule percentage of the light emitted during an hour of time, those 1500 years ago, travelled in a straight line to the spot in space where night-time side of the Earth would be during the hour of time that my camera was setup in that farmer's field, pointed toward the correct spot in constellation of Cygnus.

A supernova like this is the only known natural way to create any atom heavier than iron, which is the 26th element on our periodic table of over 100. Each speck of copper, silver and gold in your pockets or on your ring finger was formed in such an explosion, swept out into space in a thin expanding sphere of superheated glowing gas, and subsequently swept up and condensed through gravity during the formation of our solar system and in turn, our Earth. Offsprings of those Mesopotamians found and dug up bits of those precious elements which had been formed in ancestral supernovae from the depths of time. They eventually turned them into coins, rings, and cameras capable of capturing the light of the universe, and computers which let many other people, themselves made completely of matter cooked by ancient stars, view those photos.

The supernova remnant is named the Cygnus Loop, otherwise known as the Veil Nebula. This photograph was made from 95 25-second exposures taken through a 250mm lens at f/6.3 and ISO 1600, with a Sony A7II camera, and is cropped to 3000x2000 pixels, about 1/4 of the full frame. A Vixen Polarie rotated the camera to track the stars, an intervalometer clicked the camera's shutter every 28 seconds, a standard tripod held the whole assembly still. The excellent freeware program DeepSkyStacker combined the 95 photos (plus about 80 simple calibration photos which let the program compensate for flaws in the camera and lens) into one image of much higher quality than any of the individual photos. Subsequent manipulation in Lightroom brightened up the nebula a bit and darkened the light-polluted background sky. 142 subsequent photos were spoiled by slippage of the zoom lens down to 120mm once it was pointed straight upward, and eventually dew accumulation on the lens. Note to self: Tape down the zoom ring before shooting.

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