Butterfly Cluster Characteristics - Essay Example

“Most of the bright stars in this cluster are hot, blue B type stars but the brightest member is a K type orange giant star, BM Scorpii, which contrasts sharply with its blue neighbors in photographs. BM Scorpii is classed as a semi-regular variable star, its brightness varies from magnitude +5.5 to magnitude +7.0. Estimates of the Butterfly Cluster's distance have varied over the years, with a mean value of around 1,600 light-years, giving it a spatial dimension of some 12 light-years. Modern measurements show its total visual brightness to be magnitude 4.2” (www.answers.com....)
“Butterfly Cluster (M6, NGC 6405)
The details are as under:
Visual magnitude: 5.3
Angular size: 25′
Diameter: 20 light-years
Age: About 50 million years
Distance: 2,000 light-years
Position: R.A. 17h 40.1m, Dec. −32° 13′” (Answers.com….)
Butterfly Cluster is “an open cluster in Scorpius 4° northwest of M7 which contains about 80 stars roughly in the shape of a butterfly. Visible to the naked eye, it was first noted by Giovanni Hodierna before 1654. Its most conspicuous star is an orange giant K star of magnitude 6.2.” (daviddarling info….)
California Association for Research in Astronomy, own and operate the Keck Telescopes. It is an association of the California Institute of Technology and the University of California. I conducted my observations from the Keck Telescope in this institute. My choice was for this telescope.
Keck Telescope specifications are:
“Optical design: Ritchey-Chretien
Mount: Altazimuth
Overall height: 24.6 meters
Total moving weight: 270 tons
Total weight of glass: 14.4 tons
Primary mirror:
Design: Actively controlled, segmented hexagon
Equivalent diameter: 10 meters
Figure: Concave hyperboloid
Number of segments: 36
Segment diameter: 1.8 meters
Segment thickness: 75 mm
Segment weight: 400 kg
The gap between segments: 3 mm
Segment material: Zerodur low-expansion glass-ceramic
Light collecting area: 76 square meters
Focal ratio: f/1.75
Secondary mirror:
Figure: Convex hyperboloid
Shape: Circular
Dome:
Height, Width: 30.8 x 37 meters
Moving weight: 635 tons
Total air-replacement 5 minutes
Instrumentation:
Visible band: 0.3 - 1.0 micron
Infrared band 1.0 - 27.0 micron
Adaptive Optics: 1-5 micron IR” (Keck….)
This Telescope project is managed by Gerald M. Smith. Its operations are computer-controlled. Read More