SUNSET: 
0
Photographer:
Rod Pommier
Location of Photo:
Pommier Observatory, Portland, OR, USA
Date/Time of photo:
2020-02018 through 2020-02-26
Equipment:
Celestron Compustar C14 with Starizona LF reducer/corrector, SBIG STL-11000M with Baader Planetarium HaRGB filters, SBIG AO-L Adaptive Optics at 8 Hz
Description:
This image shows dark nebulae and Bok globules silhouetted against NGC 2244, the Rosette Nebula in Monoceros. The Rosette Nebula is a star forming region and blue supergiant stars born out of this nebula, like those seen at top center, are emitting intense ultraviolet radiation that ionizes the remaining hydrogen in cloud, causing it to emit red light at the hydrogen-alpha wavelength of 656.28 nm and blue light at the hydrogen beta wavelength of 486.1 nm. That light also silhouettes remaining dark dust and hydrogen clouds in the nebula. The blue supergiant stars also emit fierce stellar winds that compress the remaining dark clouds and cause them to collapse and form additional new stars. When fragments of these dark nebulae break away and begin to form star systems, they are known as Bok Globules, named after the Dutch American astronomer Bart Bok, who described them in 1947. This images centers on the many dark nebulae and Bok globules visible in this region. The dark feature to the right of center is known as "The Crescent Wrench" and the dark feature below center is known as "The Bug". The latter was imaged by Bok during his research using the 90-inch reflector at Kitt Peak Observatory with long exposures on film amplified by a photomultiplier tube to yield a faint outline of the feature. Happily, we amateurs can now produce highly detailed images of this feature using backyard telescopes and CCD cameras. Exposures: Ha_R:G:B = 360:70:70:70 minutes = 9 hours, 30 minutes total exposure
