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Michael A. Stecker
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Cygnus X-1 and
Sharpless-101
The red emission nebula Sh2-101 (RA 19 hrs 59.9 min and Dec. +35 degrees 17.5 min) is found within the borders of Barnard 144 in the rich Cygnus Star Cloud. Southeast of this nebula is a strong x-ray source called Cygnus X-1. This source is a binary system (distant of 2.5 kpc) consisting of the O9.7 Iab type supergiant HDE 226868 (star arrowed in the photo above). Orbiting this star is a compact optically invisible object with a period of 5.6 days. The mass of the unseen companion, significantly larger then 5 solar masses, suggests that it may be a black hole. An excellent source of information about Cygnus X-1 can be found at: http://www.oa.uj.edu.pl/research/cygx1.html
Photographic Data: An Astrophysics
155 mm f/7 EDF refractor and Nikon F2
camera were used with unhypersensitized
Kodak Pro 400 PPF film (35 mm format).
Two 50-minute exposures were made. The
negatives were stacked, processed, and
cropped in the computer.
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