The Veil Nebula is one of the most spectacular objects that can be imaged in astrophotography. Conveniently it is in the Cygnus (swan) constellation and easily viewed from my Lac Teeples observatory. The Veil is quite large and the image shown here is centered on Pickering’s Triangle region. William Herschel discovered the nebula in 1784 and noted the large overall size being “near 2 degree in length" as well as the “Branching nebulosity”. We see many very fine filaments in the nebula.
Image 1: Veil Nebula Pickering's Triangle and Witch's Broom. Superposition of Hydrogen-alpha and Oxygen-III emission lines. Imaged in November 2022 at Lac Teeples.
Pickering’s Triangle was discovered photographically in 1904 by Williamina Fleming but it was named after her boss, Edward Charles Pickering, the director of her observatory. I suggest we call it the Fleming Triangle from now on, or perhaps Williamina’s Whisk.
The red and blue image is the superposition (done manually and imperfectly) of two narrowband images of Hydrogen-alpha and Oxygen-III emission. The software I use has made a white colour appear where the intensity is highest.
The nebula is believed to be 2400 light-years away, which is relatively nearby in the Milky Way. The Milky Way galaxy is over 100,000 light-years across.
The Veil is a supernova remnant. If you were looking up in the sky when this huge star exploded (10 to 20 thousand years ago) it would have been visible from earth in the daytime, brighter than Venus.
Most emission nebulae emit primarily in a specific spectral line, the red Hydrogen-alpha line at 656nm wavelength. A separate image is shown of just this.
Image 2: Veil Nebula Pickering's Triangle. Hydrogen-alpha emission line. Imaged in November 2022 at Lac Teeples.
All emission nebulae are powered by some extremely powerful and rare energy source, usually extremely large and hot (and short-lived) stars. Even these huge power sources tend to be limited in what kind of emission they can produce in the gases around them.
A supernova remnant like this was blasted by even more powerful radiation and other gases were ionized and kicked into higher energy levels, leading to strong emission lines at other frequencies. We see here an image of the blue-green Oxygen-III (Doubly-ionized Oxygen) line at 500nm which shows surprisingly clear and sharp filaments. According to Wikipedia it is this emission line that dominates the light coming from the Veil.
Image 3: Veil Nebula Pickering's Triangle. Oxygen-III emission line. Imaged in November 2022 at Lac Teeples.
This image is just part of a more complete image I’ll put together. A “normal” image will be produced (RGB) and then I intend to enhance it with these additional emission line images. The colours here, red and green-blue are true for the two emission lines observed. Unfortunately at this time of year (early December) the Veil Nebula is hitting the cottage trees in the East just as the sun goes down and I won’t be able to observe it again for several months. By the spring it will start appearing in the West early in the morning and it might be summer before I can complete this image.
Comments