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The distribution of H II regions in the local spiral arm in the direction of Cygnus

Published online by Cambridge University Press:  14 August 2015

H. R. Dickel ,
H. J. Wendker  and
J. H. Bieritz
H. R. Dickel
Affiliation:
Vermilion River Observatory, University of Illinois, Urbana, Ill., U.S.A.
H. J. Wendker
Affiliation:
Vermilion River Observatory, University of Illinois, Urbana, Ill., U.S.A.
J. H. Bieritz
Affiliation:
Vermilion River Observatory, University of Illinois, Urbana, Ill., U.S.A.

Abstract

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The apparent shapes and orientations of optical nebulae in the Cygnus X complex provide possible evidence for the existence of a symmetry in the local spiral arm which may be related to the structure of the local magnetic field within the spiral arm. We have made a preliminary determination of the distances to about 90 nebulae in the Cygnus X complex by use of the values of interstellar absorption as a function of galactic coordinates. These values of absorption were determined from a comparison of optical and radio data for the nebulae. The more prominent nebulae are clumped at a distance of about 1.5 kpc. The total range in distances is from 1 kpc to at least 4 kpc. We have attempted to fit model spiral arms to this three-dimensional distribution of nebulae by approximating the spiral arm with a truncated cylinder. It has been possible to narrow the range of permissible orientations and sizes etc. for this local section of the Orion arm.

Type
Part II/Observations of Spiral Structure in Our Galaxy
Information
Symposium - International Astronomical Union , Volume 38: The Spiral Structure of our Galaxy , 1970 , pp. 213 - 218
Copyright
Copyright © Reidel 1970 

References

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