2019 Aug. 3 ~ The western Veil Nebula in the constellation Cygnus

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Photographed at Algonquin Provincial Park, Ontario, Canada

(285 km by road north of Toronto)

between 22.14 and 22.43 EDT

* Altitude of nebula at time of exposures: ~73°

* Temperature 16° C.

 

* Total exposure time: 14 minutes

* 660 mm focal length telescope

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Description:

 

From Wikipedia:

 

The Veil Nebula is a cloud of heated and ionized gas and dust ... [that] constitutes the visible portions of the Cygnus Loop, a supernova remnant. The source supernova was a star 20 times more massive than the Sun, which exploded around 21,000 years ago. The remnants have since expanded to cover an area of the sky roughly 3 degrees in diameter. While previous distance estimates have ranged from 1200 to 5800 light-years, a recent determination of 2400 light-years is based on astrometric measurements. (The distance estimates affect also the estimates of size and age.)

 

The Hubble Space Telescope captured several images of the nebula. The analysis of the emissions from the nebula indicate the presence of oxygen, sulfur, and hydrogen. The Cygnus Loop is also a strong emitter of radio waves and x-rays.

 

The nebula was discovered on 1784 September 5 by William Herschel. When finely resolved, some parts of the image appear to be rope-like filaments. The standard explanation is that the shock waves are so thin, less than one part in 50,000 of the radius, that the shell is visible only when viewed exactly edge-on, giving the shell the appearance of a filament. Given a distance of 2400 Light Years, this gives the radius of the entire nebula as 65 light years (total width, 130 light years). At 1/50,000th of the radius, this places the thickness of each filament at around 4 billion miles, or roughly the distance to Pluto. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined.

 

Even though the nebula has a relatively bright integrated magnitude of 7, it is spread over so large an area that the surface brightness is quite low, so the nebula is notorious among astronomers as being difficult to see.

 

** For a photo of the entirety of the nebula (both west and east segments), made with a shorter focal length telescope in Sept. 2017, click here:

www.flickr.com/photos/97587627@N06/36630125664

 

For a version of this photo WITH LABELS, click on your screen to the RIGHT of the photo, or click here:

www.flickr.com/photos/97587627@N06/49336271341

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Technical information:

 

Nikon D810a camera body on onedrive.live.com/?authkey=%21AHDtOGan1KEwhSU&cid=690... on Astrophysics 1100GTO equatorial mount

 

Fourteen stacked subframes; each frame:

ISO 6400; 1 minute exposure at f/5.2, unguided

(with LENR - long exposure noise reduction)

 

Subframes stacked in RegiStar;

Processed in Photoshop CS6 (brightness, contrast, levels, colour balance, bright star masking, minor sharpening)

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Done