CRESCENT NEBULA
NGC 6888
About 4,700 light years away, NGC 6888 is formed by a fast stellar wind from the Wolf-Rayet star HD 192163, Also known as WR 136. The star is shedding its outer envelope, ejecting the equivalent of the Sun's mass every 10,000 years. This stellar wind is colliding with, and energizing, a slower-moving wind ejected by the star When It Became a red giant around 400,000 years ago. The result of the collision is a shell about 25 light-years across. Two shock waves, one moving outward and one moving inward, heats the stellar wind to X-ray-emitting temperatures. The central star WR 136 will probably undergo a supernova explosion sometime in the next million years.
Technical Data
| Bortle Scale / SQM-L | Bortle 4/5 / 20.25 - 20.36 |
| Period | July 2020 |
| Primary Scope | Takahashi CCA 250/1250 - FSQ 106/530 |
| Camera | IMX455 - CCD KAF-8300 |
| Mount | AP1100 GTO |
| Total Exposure Time | 8,75H |
| Composition | HRGBOIII |
| Location | Val Imagna (Bergamo) Italy |
© Efrem Frigeni Astrophoto