Compact HII regions in the Large Magellanic Cloud observed by ISO

Abstract

We present ISOCAM observations of five fields in the Large Magellanic Cloud centered on IRAS point sources with colors of ultracompact HII regions. Three bright sources of parsec or subparsec size, with luminosities consistent with being embedded O stars, are detected at 15 mu m in two fields belonging to the HII region N 159. Using published high resolution radio observations, it is found that two of these sources may be ultracompact HII regions with a turnover frequency above 2.4 GHz, while the other is identified with a known compact HII region. If their nature as true ultracompact HII regions is confirmed by follow-up observations, these objects can provide a first sample useful for future studies of early massive star evolution in a low metallicity environment. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) with the participation of ISAS and NASA.