ALBERT

Beschreibung: Near-infrared H - and K -band spectra are presented for 247 objects, selected from the Red MSX Source (RMS) survey as potential young stellar objects (YSOs). 195 (~80 per cent) of the targets are YSOs, of which 131 are massive YSOs ( L BOL  〉 5  x 10 3 L , M  〉 8 M ). This is the largest spectroscopic study of massive YSOs to date, providing a valuable resource for the study of massive star formation. In this paper, we present our exploratory analysis of the data. The YSOs observed have a wide range of embeddedness (2.7 〈 A V  〈 114), demonstrating that this study covers minimally obscured objects right through to very red, dusty sources. Almost all YSOs show some evidence for emission lines, though there is a wide variety of observed properties. The most commonly detected lines are Br, H 2 , fluorescent Fe  ii , CO bandhead, [Fe  ii ] and He  i 2–1 1 S– 1 P, in order of frequency of occurrence. In total, ~40 per cent of the YSOs display either fluorescent Fe  ii 1.6878 μm or CO bandhead emission (or both), indicative of a circumstellar disc; however, no correlation of the strength of these lines with bolometric luminosity was found. We also find that ~60 per cent of the sources exhibit [Fe  ii ] or H 2 emission, indicating the presence of an outflow. Three quarters of all sources have Br in emission. A good correlation with bolometric luminosity was observed for both the Br and H 2 emission line strengths, covering 1 〈 L BOL  〈 3.5  x 10 5 L . This suggests that the emission mechanism for these lines is the same for low-, intermediate- and high-mass YSOs, i.e. high-mass YSOs appear to resemble scaled-up versions of low-mass YSOs.