The Cygnus X complex is found to be associated with the Orion arm by a comparison of the recombination- line and neutral-hydrogen velocities. in the longitude range of Cygnus X, the latitude distribution of hydrogen peaks at b'1 = +10 indicating that the DR sources are distributed approximately symmetrically with respect to the hydrogen. The virial theorem suggests that the complex is unstable but is, however, confined in the Z direction by the gravitational field of the Galactic disk.
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McCutcheon et al. (1970) studied this question.