VLA Spectral Line Observations of the HII Complex G34.3+0.2
Session 13 -- HII Regions
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [13.06] VLA Spectral Line Observations of the HII Complex G34.3+0.2

A. L. Fey, R. A. Gaume (NRL), M. J. Claussen (NRAO)

Four HII regions have been detected toward G34.3+0.2 in the radio continuum. Three of these regions (components A, B, and C) are ultra-compact. The fourth, G34.3+0.2 component D, is a $\approx 1'$ (1.1~pc at 3.8~kpc) diameter ring-like HII region. We have observed the H93$\alpha$ radio recombination line emission with $\approx 11''$ spatial resolution and the 1.3~cm water maser emission with $\approx 4''$ spatial resolution toward G34.3+0.2. The observed radio recombination line emission suggests that component~D is an expanding shell source. The inferred expansion velocity of 5~km~s$^{-1}$ gives a calculated lifetime of $\sim 10^5$ years. The continuum emission from the source is preferentially brightened on one side. We suggest that this morphology may be explained by the expansion of the HII region into an anisotropic medium. The average LSR velocity of the shell source has been determined to be $\approx$ 54.1~km~s$^{-1}$. The observed spatial distribution of the H$_2$O masers in the G34.3+0.2 complex has identified two new regions of star formation which are not associated with any radio continuum emission.