(1) |
To change color or reverse image, from right toolbar select histogram.
Color choice or reversed image may improve image analysis.
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(2) |
From right toolbar, choose the distance tool. Place cursor on left
edge of NGC 7027 and drag cursor horizontally across image. Read
size below image. This is the 'time' size of image. To convert to angular
size, multiply time size by 15. The result is the angular size of
NGC 7027 in arcseconds. Record this value
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(3) |
To calculate distance to source, use:
d = 57400/(angular size)
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NGC 7027 is a planetary nebula located about 3000 light years from us
in the constellation Cygnus. A planetary nebula is the shell of gas
ejected from a dying star. The outer material of the star has been
lifted off and expands at speeds of 20 to 30 km/s. A typical planetary
nebula has a diameter of 1 light year. How do your results of angular
size and distance compare with a typical planetary nebula?