Masers in Massive Star-forming Regions Associated with the Brightest Steep-Spectrum [ITAL]IRAS[/ITAL] Point Sources

Abstract

Twenty-four bright, steep-spectrum far-infrared IRAS point sources, which were originally discussed by Hughes & MacLeod, have been searched for hydroxyl, water, and methanol masers and for formaldehyde absorption features. Distances and spectral types for the stars exciting these masers were estimated using radio continuum, IRAS spectra, and maser velocity data. It is found that 21 of the 24 sources are regions of massive star formation containing stars earlier than type B2. We report the discovery of five new OH masers, one new 6.7 GHz CH3OH maser, and two new 12.2 GHz CH3OH masers toward these IRAS sources. By contrast, no 4.765 GHz excited-OH masers were found toward these sources. This sample contains only star-forming regions; there are no planetary or reflection nebulae or extragalactic sources present, as seen in samples with less extreme IRAS colors.