VLT/ISAAC H-band spectroscopy of embedded massive YSOs

We have performed intermediate resolution ( R similar to5000), high signal-to-noise H-band spectroscopy of a small, initial sample of three massive embedded young stellar objects (YSOs), using VLT/ISAAC. The sample has been selected from sources characterised in previous literature as being likely of OB spectral type, to be unambiguously associated with bright ( H less than or equal to 14) single point sources in the 2MASS database, and to have no optical counterparts. Of the targets observed, one object shows a similar to B3 spectrum, similar to a main sequence object of the same spectral type. A second object exhibits weak He. and H emission, indicating an early-type source: we detect He.. absorption, which supports a previous indirect derivation of the spectral type as mid-O. The third object does not show absorption lines, so no spectral type can de derived. It does, however, exhibit a rich spectrum of strong, broad emission lines and is likely to be surrounded by dense circumstellar material and at a very early evolutionary stage. Our results from this very small sample are in agreement with those of Kaper et al. ( 2002), who also find spectra similar to optically visible main sequence stars, together with emission line objects representing a very early evolutionary phase, in their much larger sample of K-band spectra.