The galactic plane region near

I. HII region NRAO 655

¹ Dept. of Physics, University of Alberta, Edmonton, Canada
² Dept. of Electrical and Computer Engineering, University of Alberta, Edmonton, Canada

Corresponding author: D. Routledge, routle@ee.ualberta.ca

Received: 29 August 2000
Accepted: 24 November 2000

Abstract

We present new Canadian Galactic Plane Survey radio continuum and 21 cm H I line observations of NRAO 655 (G93.4+1.8), plus radio recombination line observations, and optical H-line observations. The radio spectrum of NRAO 655 confirms its emission as thermal. From the 21 cm H I data we find an atomic hydrogen cavity associated with this object at km s. The cavity corresponds in position and size to the brightest radio continuum emission from NRAO 655. The corresponding kinematic distance is 8.8 kpc, placing NRAO 655 in the Perseus Arm. NRAO 655's linear size is therefore 70 pc 130 pc. To confirm the 21 cm H I velocity we present the first recombination line detection of NRAO 655 (H158 line, km s), and the first observations of a molecular cloud coinciding with NRAO 655 (at km s). The first optical detection of 656 nm H emission line features in NRAO 655 is also presented, and the H emission line brightness is determined. We suggest that the eastward extension of this strongly asymmetric object originates in a champagne outflow, and we estimate its age. We show that a single early-type star cannot be responsible for the outflow, whereas a group of later-type stars would suffice. A partial H I shell is seen adjacent to the brightest part of NRAO 655; we suggest that it has been formed by dissociation of H in the molecular cloud.