BROAD-BAND INFRARED-SPECTROSCOPY OF MASSIVE YOUNG STELLAR OBJECTS

We present intermediate resolution 0.9-2.5 mu m IR spectra of 12 highl y reddened stars, including some well known and some unfamiliar source s. A new technique for extracting calibration curves from standard sta r data is employed, and is found to be very successful. The reddening to each object is fully discussed and is calculated from both the cont inua (which was split into short-and long-wavelength regions lambda la mbda < 1.5 mu m and lambda lambda > 1.5 mu m) and the HI lines. We fin d that, typically, there is consistency between the values derived fro m the HI lines and the short-wavelength continua, but not with the val ue from the long-wavelength continua. This discrepancy is due to an IR excess at lambda lambda greater than or similar to 1.5 mu m, which is consistent with emission from hot dust (we derive dust temperatures i n the range 750-1500K). We note that some of our sources have highly d iscrepant Paschen decrements, and may have a significant amount of sca ttered light for lambda lambda < 1.5 mu m. The spectra show a variety of metallic emission lines and some evidence for different distinct em ission regions in the same source. The range of line-to-continuum cont rast between the sources is high, and where previous observations have been taken, there is evidence of variability of emission line strengt h in some sources.