Magnetic field structure of the cometary HII region G34.3+0.2 - Magnetic field structure of G34.3+0.2

We observed the hydroxyl (OH) masers in the ground-state 1665 and 1667 MHz transitions toward the cometary HII region G34.3+0.2 with the Very Long Bas eline Array (VLBA). Our observations were sensitive to both right and left circular polarizations with a spectral resolution of 0.176 km s(-1) and an angular resolution of 8 x 31 mas. We detected 120 maser features in a regio n of 3 x 6 arcsec, including 15 Zeeman pairs separated by an average distan ce of only 2 mas were identified. The OH masers are associated with two new ly formed stars in the G34.3+0.2 complex. One star ionizes a weak, ultra-co mpact HII region (source 8) and has a magnetic field orientation predominan tly away from us. The other star, or stars, power the dominant cometary HII region (source C) and the magnetic field along the northern rim of the com etary source is directed toward us.