Program: GN-2007A-Q-34

W51 IRS2 is a compact HII region which may harbor a dozen OB stars, 3 ultracompact HII regions and 2 enigmatic objects: IRS2E and IRS2W. IRS2 is the brightest region in the W51 giant HII region complex. IRS2E and IRS2W are 2 bright near infrared sources that may represent two massive young stellar objects. While IRS2W is also a radio source, but shows no mid infrared emission, IRS2E is a bright mid infrared source without any appreciable radio emission. Both sources are embedded in extended nebular emission that precludes the access of their photospheres. We propose to use NIFS in combination with the ALTAIR facility adaptive optics system and laser guide star to obtain high angular resolution K band spectra of IRS2E and IRS2W as our primary goal. The high resolution achieved by NIFS reduces the nebular contamination in the vicinity of the sources, allowing us to probe the photosphere of these objects for the first time. As a secondary goal, we will obtain the spectral types of the ultracompact HII regions W51d1 and W51d2 and some of the OB star candidates identified by Goldader & Wynn-Williams that may be the ionizing sources of W51 IRS2 compact region.