AN ANALYSIS OF IRAS-IDENTIFIED H-II REGIONS AND THEIR RADIO PROPERTIES

We selected 82 objects from the list of 2298 H II regions previously identified by Hughes & MacLeod from the IRAS Point Source Catalog, to see if they contained radio sources. We selected half of them as objects with values of Y = log (F25/F12) greater-than-or-equal-to 0.8, and half with values of 0.3 less-than-or-equal-to log (F25/F12) less-than-or-equal-to 0.5. Of all the objects, 72% had at least one associated radio source, and a total of 78 radio sources were detected. Those with larger values of log (F25/F12) had significantly larger values of peak, integrated, and 100 mum flux densities than the others. Most of the radio sources have diameters of <3'', which was the limit to the angular resolving power of the survey. Those sources with large Y that had associated radio sources generally had associated masers, and thus probably contained star-forming regions, while the others could contain protostars which are still accreting but have not yet reached the stage of turning on their ionizing radiation. Those with smaller Y appear to be due to stars with high IR and ionizing radiation and could be T Tauri type stars. All 2298 objects appear to have a strong galactic concentration. A comparison with the work by Wood & Churchwell show that the latter had somewhat different results. They used different criteria to select 1717 objects, which they identified as regions containing chiefly O-type stars. They observed 75 of them and found that 63% contain radio sources. There was little correlation between the two sets of sources, but the success rate in both cases was about equal to the confidence level for the set selected by Hughes & MacLeod.