Angular Diameters of Compact Planetary Nebulae

Abstract

We have obtained H$\alpha$ CCD images of 21 compact planetary nebulae in the galactic bulge. All objects are resolved and, after deconvolving the seeing disk, we find diameters of 1--2${}^{\prime \prime }$ with typical uncertainties of 20\%. The values are generally in good agreement with radio measurements but are smaller than older optical measurements. Based on the new values, we find that the Shklovsky method for distance determination greatly overestimates the actual distance for all of our objects.

arXiv comment(LaTeX 8 pages; send email to [email protected] for figures). Accepted for publication in Astronomy and Astrophysics. ESO-TRB02