Michael A. Stecker
mastecker@gmail.com



 
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Sh2-308 "Dolphin Head Nebula"
(with Oxygen-III data)
The Dolphin Head Nebula (aka: Sharpless 308, RCW 11, or LBN 1052) is about 8 degrees south of the star Sirius. The nebula is bubble-like and surrounds a Wolf–Rayet star named EZ Canis Majoris. This star is in the brief, pre-supernova phase of its stellar evolution. The nebula is about 4,530 light-years away from Earth. Its central star is EZ Canis Majoris, a Wolf–Rayet star, also designated EZ CMa or WR 6. Its apparent magnitude varies from 6.71 to 6.95. Its spectral type indicates that the star is very hot and luminous. The spectrum shows that it is devoid of hydrogen at the surface. It will eventually explode into a supernova, therefore subsuming the nebula.
Formation:
The nebula was formed about 70,000 years ago by the star EZ Canis Majoris throwing off its outer hydrogen layers, revealing inner layers of heavier elements. Fast stellar winds, blowing at 1,700 km/s (3.8 million mph) from this star, create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of the star's evolution. The hydrogen composing the nebula is ionised by intense ultraviolet radiation. The nebula is approximately 60 light-years across at its widest point.
file:Sh308DH-JRF-HRGBOIIInu2A-MAS1x2b.jpg
 .
 Bluer version at:
...Sh308DH-JRF-HRGBOIIInu2A-MAS1x2.jpg

Photographic Data
 telescope:
Sky-Watcher Quattro 250P, 10-inch f/4 Newtonian telescope (FL= 1,000 mm)
 
mount and guiding
Astro-Physics 1200 GTO

 imaging camera:
ZWO ASI2600MC-Pro color astro-camera.  Imaged on September 17, 2023.

exposure:
 ?

guiding:
SVBony 60 mm f/4 guide scopr (FL= 240 mm) with ZWO ASI1200Mini guide camera
 
processing
Aquired and stacked by James Foster with Maxim DL.  Post-processed in Adobe Photoshop Elements by Michael Stecker.
 .
photographic site:
James Foster's observatory at Frazier Park California
 https://en.wikipedia.org/wiki/Frazier_Park,_California
(Bortle 4 at 5,500 feet elevation)
 
 
 

James Foster's version: HaRGB plus Oxygen-III filtered light
file: nuDolphin-HRGBOIIInu2A.jpg
 
 
 
 
 
 
 
Sh2-308 "Dolphin Head Nebula"
(without Oxygen-III data)
file: Sh2-308DolH-JRF10NewtHaRGB112023-ymbg.jpg
 
 
 
 
In Memorium
White Feral cat at James Foster's observatory
June, 2023 - November 24, 2023 
 
White feral cat disappeared from James Foster's property on the same night he photographed the Dolphin Head nebula in Oxygen-III light.