Determination of the Distance to B361 by a Modified Version of the Wolf Diagram

Current estimates, based on the same star-count analysis, of the distance to the globule Barnard 361 range from 300 pc to 650 pc. All the problems associated with the estimates have been fully rectified in this study, and a modification has been made to the classical Wolf diagram to improve the accuracy in the distance determination. A reference field was carefully selected colse to the globule but well outside the globule boundary, and star counts for this field were performed on the blue POSS plate in order to set up the reference magnitude sequence appropriate to the general area of B 361. From the reference sequence, the stellar density function has been derived specifically for the direction toward the globule. Correction was made for the general interstellar extinction, and the luminosity funciton with the Wielen's dip was adopted. The resulting density function clearly reveals the existence of the local Cygnus-Orion arm in the direction of B361 at about 700 pc away from the Sun. Analysis of the star-count data for the program field locates the globule at distance 600+-5pc; thus, the globule is an object located in the Cygnus-Orion arm, residing somewhat toward its leading edge.