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We present $K$-band spectra of the near infrared counterparts to IRS2E andIRS2W which is associated with the ultracompact HII region W51d, both of themembedded sources in the Galactic compact HII region W51 IRS2. The high spatialresolution observations were obtained with the laser guide star facility andNear infrared Integral Field Spectrograph (NIFS) mounted at the Gemini Northobservatory. The spectrum of the ionizing source of W51d shows the photosphericfeatures NIII (21155 \AA) in emission and HeII (21897 \AA) in absorption whichlead us to classify it as an young O3 type star. We detected CO overtone inemission at 23000 \AA in the spectrum of IRS2E, suggesting that it is a massiveyoung object still surrounded by an accretion disc, probably transitioning fromthe hot core phase to an ultracompact HII region.

High Spatial Resolution Spectroscopy of W51 IRS2E and IRS2W: Two Very Massive Young Stars in Early Formation Stages