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2003ApJ...587..701F - Astrophys. J., 587, 701-713 (2003/April-3)

H I absorption toward ultracompact H II regions: distances and galactic structure.

FISH V.L., REID M.J., WILNER D.J. and CHURCHWELL E.

Abstract (from CDS):

The Very Large Array was used to observe H I absorption against 20 compact and ultracompact H II (UC H II) regions, thereby resolving the kinematic distance ambiguity to these sources. Combining these results with other sources whose distances were resolved through H I absorption, the half-width at half-maximum of the distribution of source height above and below the Galactic plane is found to be 35±2 pc within the solar circle. The vertical height distribution is used to investigate the predictive accuracy of the Galactic latitude in resolving the kinematic distance ambiguity to UC H II regions without the need for H I observations. For a large difference between far and near kinematic distances, high accuracy can be achieved by choosing the kinematic distance closer to 1.84|b|–1 kpc, where b is the Galactic latitude in degrees.

Journal keyword(s): Galaxy: Disk - Galaxy: Structure - ISM: H II Regions - Radio Lines: ISM

CDS comments: p. 702 : Calibrator 1849+005 not identified