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Distance: Sadr 1,800 Light Years
Magnitude: Sadr 2.23
Size: Sadr 150 times the size of our sun
Telescope: Borg 71
Exposures: Ha 26×600
This image was captured from my home in a Bortle 6/7 region. It is a four panel mosaic with the center of the mosaic focused on the star Sadr. This is the central star that forms the intersection of the asterism that forms the constellation Cygnus.
IC 1318, the Gamma Cygni Nebula, is to the left of Sadr. It is a very large emission nebula that spans about 200 light years. It consists of IC1318A, IC 1318B, and IC 1318C. All three sections of IC 1318 are 4,900 light years away. IC 1318A is 50 arc minutes in size. IC 1318B is also 50 arc minutes in size. IC 1318C is 40 arc minutes in size. LDN 889 is a dark nebula that separates IC 1318B and IC 1318C.
NGC 6914 is 6,000 light years away with a size of 5 arc minutes. It is a small reflection nebula located to the left of IC1318A and above IC1318B in my image.
IC 1311 is an open star cluster. It is 19,000 light years away with a magnitude of 13.10. In my image, it is located towards the top right corner and appears brighter than the surrounding background nebula.
NGC 6910 is an open star cluster with a magnitude of 7.4. In my image it is located just above and to the left of Sadr. Located at a distance of 3,700 light years, it has a size of 10 arc minutes.
NGC 6888, the Crescent Nebula is seen in the lower right of my image. At 4,100 light years away it measures 18’ arc minutes in size. The Crescent Nebula is an emission nebula in the constellation Cygnus. The illuminating source is the Wolf Rayet star WR 136. In general a Wolf Rayet star is a very large hot star that is rapidly shedding mass in the form of ultraviolet radiation. WR 136 is estimated to be 250,000 times brighter than our sun, 15 times more massive, and with a temperature of 70,000 Kelvin. WR 136 is ejecting matter at a speed of 6.1 million kilometers per hour. This high speed matter hits the ambient dust and gas and gives the Crescent nebula its shape. Part of the surrounding gas and dust is previously ejected material from WR 136 when it was a red giant about 250,000 years ago.
It is the gas and dust in the surrounding medium that is compressed in to a thin shell giving the nebula its shape. There are actually two waves of shocked gas, one corresponding to the shocked stellar wind and the other to shocked interstellar gas. The hot interior of this bubble is where the energy is stored and subsequently used for driving the entire structure.
The following smaller items are also seen in my image:
Collinder 419 is an open star cluster with a magnitude of 13.10. It has a size of 4 arc minutes. It is above and to the right of Sadr in my image.
Collinder 421 is an open star cluster with a size of 7 arc minutes. It is above NGC 6910 in my image.
M29 is an open star cluster located 4,000 light years away with a visual magnitude of 7.1 There are about 50 stars in this cluster with several of them classified as type BO which are very young and very hot stars. In my image it is located below and to the left of Sadr, almost in line with the Crescent nebula.
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