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Description
We have observed the massive star-forming region IRAS 18507+0121 at millimeter wavelengths in 3mm continuum emission, H^13^CO+ (J=1-0) and SiO (v=0,J=2-1) line emission, and at near-infrared (NIR) wavelengths between 1.2 and 2.1{mu}m. Two compact molecular cores are detected: one north and one south, separated by ~40". The northern molecular core contains a newly discovered, deeply embedded, B2 protostar surrounded by several hundred solar masses of warm gas and dust, G34.4+0.23 MM. Based on the presence of warm dust emission and the lack of detection at NIR wavelengths, we suggest that G34.4+0.23 MM may represent the relatively rare discovery of a massive protostar (e.g., analogous to a low-mass "Class 0" protostar). The southern molecular core is associated with an NIR cluster of young stars and an ultracompact HII region, G34.4+0.23, with a central B0.5 star. The fraction of NIR stars with excess infrared emission indicative of circumstellar material is greater than 50%, which suggests an upper limit on the age of the IRAS 18507+0121 star-forming region of 3Myr.
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