The Cocoon Nebula (other names: cocoon nebula, IC 5146 –name just for the cluster-, Caldwell 19, The circular HII region is catalogued separately as Sharpless-2 125;) are emission and reflection nebula while in the constellation Cygnus, 4,000 ly away from us . Like all areas of new star formation it stands out in red, glowing, hydrogen gas excited by the young, hot stars and blue, dust-reflected starlight at the edge of an otherwise invisible molecular cloud. It includes the bright central star BD +46°3474. This powerful B-type star, is the dominant illumination source of IC 5146 and lies in the foreground of a large molecular cloud complex, "digging" a dark cavity around it, within the existing molecular cloud of dust and gas from which it was born. The surface temperature of the star ranges from 30,000-35,000 degrees Celsius, which is responsible for the ultraviolet flux that ionizes the surrounding existing gases. But the long dusty filaments that appear dark in this visible light image are themselves hiding stars in the process of formation, seen at infrared wavelengths. IC 5146 is the open star cluster that is present in the nebula, also known as Collinder 470, with brightness (visual magnitude) +7.2. The cluster is located 4,000 light years from us, while its central star formed only 100,000 years ago. These stars are low-mass stars -with masses similar to that of the sun us- but much younger (aged about 1 million years). The nebula covers 12’ in the sky area and has 15 light years real dimensions.​

 

Technical data

 

Ηα-LRGB

Ha : 9x600s, bin1

Lum 12x600s, bin1

RGB 12x300s, bin2 each.

Mount AP Mach1 GTO

Scope : Vixen VC200L

Camera QSI 683,  -20 C

 

Frames taken in Skyros Island, Greece, Summer 2014.