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NGC 6888 Crescent Nebula
NGC 6888 is commonly known as the Crescent Nebula which is one of the more intriguing objects in our galaxy. This annular nebula circumscribes a 7.5- magnitude Wolf-Rayet star known as HD 192163. Wolf-Rayet stars are extremely luminous and hot stars that shed mass at enormously high rates, in many cases after passing through a supergiant stage. This material travels at speeds as high as 3,000 km per second until it smashes into gases that previously constituted the star's outer atmosphere. The Crescent has long been believed to be the result of such a collision. Studies show it to be a prolate ellipsoid, 25 by 16 light-years across, that is tilted at a 45 degree angle to our line of sight. The Einstein and Rosat spacecraft revealed that X-rays emanate not from the nebula's cavity but from its visually brightest parts. The X-ray emissions originate in filamentary structures close to the nebula's inner border, suggesting that they are generated as material cools after being shocked by the fast wind for HD 192163. The nebula's outer edges, by contrast show the first point of contact between the advancing Wolf-Rayet wind and the atmosphere of the former red supergiant.
Acquired 11-Jul-10, 2 hours 40 min @ ISO 1600, flats, darks, bias
New Moon, temperature ranged 84 - 75⁰F
Modified XSi WO ZS80FD with AstroTech FF and IDAS LPS at F6.9 on Celestron CGE mount, guided with PhD Guiding using QGuider on an ST80
NGC 6888 Crescent Nebula
NGC 6888 is commonly known as the Crescent Nebula which is one of the more intriguing objects in our galaxy. This annular nebula circumscribes a 7.5- magnitude Wolf-Rayet star known as HD 192163. Wolf-Rayet stars are extremely luminous and hot stars that shed mass at enormously high rates, in many cases after passing through a supergiant stage. This material travels at speeds as high as 3,000 km per second until it smashes into gases that previously constituted the star's outer atmosphere. The Crescent has long been believed to be the result of such a collision. Studies show it to be a prolate ellipsoid, 25 by 16 light-years across, that is tilted at a 45 degree angle to our line of sight. The Einstein and Rosat spacecraft revealed that X-rays emanate not from the nebula's cavity but from its visually brightest parts. The X-ray emissions originate in filamentary structures close to the nebula's inner border, suggesting that they are generated as material cools after being shocked by the fast wind for HD 192163. The nebula's outer edges, by contrast show the first point of contact between the advancing Wolf-Rayet wind and the atmosphere of the former red supergiant.
Acquired 11-Jul-10, 2 hours 40 min @ ISO 1600, flats, darks, bias
New Moon, temperature ranged 84 - 75⁰F
Modified XSi WO ZS80FD with AstroTech FF and IDAS LPS at F6.9 on Celestron CGE mount, guided with PhD Guiding using QGuider on an ST80