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Recombination Line Survey of Galactic H II Regions.

1967; Institute of Physics; Volume: 72; Linguagem: Inglês

10.1086/110461

1538-3881

III Reifenstein E. C., T. L. Wilson, B. F. Burke, P. G. Gomez,

Astronomical Observations and Instrumentation

A survey of 109a (5009 MHz) hydrogen recombination line radiation has been undertaken with the XRAO 140-ft telescope. The first phase of the survey has been completed, and consists of observations of the 80 most intense sources near the galactic plane. The recent 11-cm continuum survey of Altenhof and Mezger has been used as a finding list. Line radiation has been detected in 52 of the observed sources, and radial velocity measurements have been made. The large-scale distribution of these sources will eventually lead to a galactic model, when later phases of the survey have been completed. Special attention has been given to Cygnus X and the galactic center. In Cygnus X, 19 sources were observed, and the l09a line was detected in 12 of these. An unexpectedly large fraction of sources both in Cygnus X and in the galaxy as a whole show no recombination line. This indicates that there may be a larger fraction of old supernova remnants, having relatively flat spectra, than was previously suspected. The galactic center observations have shown line radiation in the sources (0.5, -0.0), (0.7, -0.0),and (1.1, -0.1) Xo line of normal width could be seen in (0.0, 0.0), (0.9, +0.1), or (0.2, -0.0), although the presence of line radiation of very wide velocity spread could not be ruled out. Xote that this is a correction to the earlier observation of P. G. Mezger and B. Hoglund (Astrophys. J. 147, 490,1967), who attributed the lines of (0.5, -0.0) and (0.7, -0.0) to the sources (0.2, -0.0) and (0.5, -0.0). This work was supported in part by the Joint Services Program [Contract DA-3 6-039-AM C03200 (E)]. The XRAO is operated by Associated Universities under contract with the Xational Science Foundation.