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Dark Tower - A Bridge to Nowhere
Near Open Cluster NGC 6231

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DESCRIPTION

NASA ASTRONOMICAL PICTURE OF THE DAY (APOD)  April 27, 2011

 

The Dark Tower in the constellation of Scorpius is an elongated dark cloud of dust and gas embedded in a rich sea of stars. It is known as a cometary globule where intense UV radiation from very hot OB-type stars in NGC6231 (off the top edge of the image) sculpts the resulting columnar structure of the Dark Tower. The UV radiation is sufficiently strong to ionize hydrogen, producing an ominous pink glow around the top of the Dark Tower and similarly to ionize the background medium, such as the interesting "bridge to nowhere" of H-alpha light extending from the tip of the Dark Tower toward the left side of the image. There are several blue reflection nebula embedded within the Dark Tower. These structures are stellar nurseries. The Dark Tower is 40 light years across and 5,000 light years distant.



Constellation: Scorpius
RA: 16hr 45m 58s
Distance: 5,000 light years
Image Size: 42' x 42'
DEC: -41d 15m 5s
North: 2 o'clock position

Exposure: 8.5 hrs Total; 3.5 hrs H-a, 5 hrs RGB
Telescope: 14.5
Mount: Software Bisque Paramount ME
OAG: Astrodon MonsterMOAG
Acquisition: CCD AutoPilot4
Calibration: CCDStack2
Observatory Site: Riverland Dingo Observatory, Moorook, S. Australia
Camera: Apogee U16M
Filters: Astrodon 5 nm H-a, Gen 2 LRGB
Guider: SBIG ST-402
Camera Operation: MaximDL5.08
Processing: Photoshop CS5 Extended
Image Date: 08.04.10

A synthetic luminance was created from the unbinned RGB data. The H-a data were added to the synthetic luminance and to the red and blue color channels.