Australia Telescope Compact Array Survey of Candidate Ultracompact and Buried H II Regions in the Magellanic Clouds

摘要

We present a systematic survey for ultracompact (UC) H II regions in the Magellanic Clouds. Understanding the physics of massive star formation (MSF) is a critical astrophysical problem. The study of MSF began in our Galaxy with surveys of UC H II regions, but before now this has not been done for other galaxies. We selected candidates on the basis of their Infrared Astronomical Satellite (IRAS) colors and imaged them at 3 and 6 cm with the Australia Telescope Compact Array. Nearly all of the observed regions contain compact radio sources consistent with thermal emission. Many of the sources are related to optically visible H II regions, and often the radio emission traces the youngest and densest part of the H II region. The luminosity function and number distribution of Lyman continuum fluxes of the compact radio sources are consistent with standard stellar and cluster initial mass functions. This type of systematic assessment of IRAS diagnostics is important for interpreting Spitzer Space Telescope data, which will probe similar physical scales in nearby galaxies as IRAS did in the Magellanic Clouds.