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Tuesday, January 21, 2014

Sh2-221, a supernova remnant in Auriga


I think, this is the first three band color image, showing the whole Sh2-221, in the World.

This was one of the most difficult targets I have done so far. Supernova remnant Sh2-221, SNR G160.4+02.8, HB9, locates in constellation Auriga and has an angular dimensions about 2.5 x over 3 degrees. I never seen or red about the extended ionized Oxygen area, visible in my image as blue.
About 33h of exposures with extremely fast camera optics, Canon EF 200mm f1.8 @f1.8, was needed for this image. Total exposure time for the mosaic image, with a Planetary Nebula Sh2-216, is about 58h.

This could be the very first narrow band color image in the world out of this target. Generally, there are very few images of it. I couldn't find an other image showing the whole remnant  nor other channels, than H-a.
I have shot this area before but at the time part of the Sh2-221 was missing. This new image of mine is much more accurate and deep.

Sh2-221,  Sh2-221, SNR
A supernova remnant in Auriga, Ra 04 43 21 Dec 46 42 06

Mapped colors
Mapped colors from the emission of ionized elements,
R=Sulfur, G=Hydrogen and B=Oxygen.
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Visual spectrum
Image is in Natural color palette from the emission of ionized elements, 
R=Hydrogen + Sulfur, G=Oxygen and B=Oxygen + Hydrogen.
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INFO

The Supernova remnant Sh2-221 (SNR G160.4+02.8, HB9) locates in constellation Auriga, about one degree West from Capella. (Doesn't show in my image) The distance from the Earth, 2600 light years,  is determined recently at 2007. This object was recognized as a supernova remnant back at seventies.


A two panel mosaic image of Sh-221 and Sh2-216
Two ways to end a life of the star in a same seven degrees field of view!

Just next to Sh2-221 locates a closest known planetary nebula, Sh2-216. This is also a very rarely images target, due to its low surface brightness and large angular dimension. This mosaic image covers over seven degrees of sky vertically. (The Moon has an apparent dimension of 0.5 degrees.)  Mosaic is made out of my new data of Sh2-221 and an older material of Sh2-216. Some new exposures was taken for the Sh2-216 to match the background for a mosaic image. 

Image shows two different ways to end a life of the star. At left, as a Supernova and at right as a Planetary Nebula. (Massive stars will go to a Supernova, after burning out all of the Hydrogen. There will be a Neutron star or a Black Hole left behind. Lighter stars, as our Sun, will turn to a Planetary Nebula, after ran out of Hydrogen. There is a core of the star left behind, it's called a White Dwarf  and it will cool down gradually. ) 

Mapped colors
Mapped colors from the emission of ionized elements,
R=Sulfur, G=Hydrogen and B=Oxygen.
Buy a photographic print from HERE

Visual spectrum
Image is in Natural color palette from the emission of ionized elements, 
R=Hydrogen + Sulfur, G=Oxygen and B=Oxygen + Hydrogen.
 Buy a photographic print from HERE

A labeled image

Note. A circle, size of the Moon, is marked as a scale. Both objects are very large targets, as can be seen.

Orientation in Auriga



Technical details

Processing work flow:
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Levels, curves and color combine in PS CS3.

Optics, Canon EF 200mm camera lens at f1.8
Camera, QHY9 with the Baader narrow band filter set, H-a, S-II and O-III
Guiding, Meade LX200 GPS 12" and a Lodestar guider
Image Scale, ~5 arcseconds/pixel

Exposures for the Sh2-221 SNR
H-alpha: 51 x 1200s = 17h
O-III:  21 x 1200s = 7h
S-III: 27 x 1200s = 9h

Exposures for the Sh2-216 Planetary Nebula
H-alpha: 30 x 1200s = 10h
O-III:  18 x 1200s = 6h
S-III: 27 x 1200s = 9h
Total exposure time 58h


Animation of the narrow band channels

In this animation each color channel of Sh2-221 is shown separately. A special technique of mine, Tone Mapping, was used to dig out some extremely dim data.

A set of individual 20 min. exposures for used channels.

Note. 
Images are calibrated with Bias corrected Flats and Darks. A very strong none linear stretching is performed to the images. A hint of the Planetary Nebula Sh2-216 can be seen at most right.

H-alpha, the light emitted by an ionized Hydrogen

A single 20 min. exposure of H-alpha

S-II, the light emitted by an ionized Sulfur

A single 20 min. exposure of S-II

O-III, the light emitted by an ionized Oxygen

A single 20 min. exposure of O-III




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